A method for preparing high temperature resistant thermal expansion epoxy resin foam material

Abstract

The invention belongs to the technical field of epoxy resin foaming materials, and discloses a preparation method of a high temperature resistant heat expansion epoxy resin foam material, wherein the preparation method comprises the following steps: stirring bismaleimide, o-diallyl bisphenol A, heat expansion microspheres, epoxy resin and 4,4-diaminodiphenyl sulfone at 130-150°C for 2-4 hours to obtain a mixed resin liquid, placing the mixed resin liquid in a mold, hot pressing at 60-90°C and 0.1MPa, and then cooling to room temperature to form a heat expansion resin sheet with a thickness of 1-5mm, then placing the heat expansion resin sheet in a mold, and then placing the mold with the heat expansion resin sheet in a flat vulcanizer, and curing and foaming to obtain a high temperature resistant heat expansion epoxy resin foam material. The invention improves the heat resistance of the high temperature resistant heat expansion epoxy resin foam material, and ensures that the attenuation of its mechanical properties at room temperature and high temperature conditions is small.

Description

Technical Field

[0001] The invention belongs to the technical field of epoxy resin foaming materials and relates to a method for preparing a high-temperature resistant thermal expansion epoxy resin foam material. Background Art

[0002] Epoxy resin, as a typical thermosetting plastic, epoxy resin foam material prepared with it as the matrix has the advantages of high temperature resistance, short curing time and excellent mechanical properties, and is therefore widely used in many fields. However, with the rapid development of science and technology, society's requirements for material performance are also increasing. The epoxy resin foam material prepared by the existing technology has gradually failed to meet the society's high standards in terms of heat resistance and mechanical properties. Therefore, how to further improve the heat resistance and mechanical properties of epoxy resin foam materials has become an important issue that needs to be solved urgently.

[0003] For example, in Reference 1 (Preparation and Performance Study of Solid Epoxy Resin Foaming Material [D]. Hubei University of Technology, 2019.), solid epoxy resin is used as the matrix, dicyandiamide is used as the curing agent, and 4,4'-oxybisbenzenesulfonylhydrazine (OBSH) is used as the foaming agent to prepare solid epoxy foaming material by chemical foaming method. However, the Tg (glass transition temperature) of the prepared solid epoxy resin foaming material is only around 120°C, and the mechanical properties of the solid epoxy resin foaming material will begin to seriously decay at 90°C.

[0004] Reference 2 (Epoxy composite foams with excellent electromagnetic interference shielding and heat-resistance performance [J]. Journal of Applied Polymer Science, 2018: 46013. DOI: 10.1002 / app.46013.) introduces a multi-scale conductive network system consisting of multi-walled carbon nanotubes (MWCNTs) and nickel-plated carbon fibers (NiCFs) into the foam material. Benefiting from the synergistic effect between NiCFs and MWCNTs, the final epoxy resin foam material has a Tg of 178.3°C. However, the epoxy resin foam material produced has not yet reached the standard required by the aviation field for stable use in an environment of 180°C. In order to ensure that its mechanical properties at high temperatures do not significantly decay, the glass transition temperature (Tg) of the produced material must be significantly higher than its working environment temperature. Specifically, the Tg value needs to be at least 30°C higher than 180°C. In this way, when the epoxy resin foam material is used at 180°C, its mechanical properties can remain stable, thereby meeting the stringent requirements of the aviation field.

[0005] Therefore, it is of great significance to study a preparation method of a high temperature resistant thermal expansion epoxy resin foam material to solve the above problems. Summary of the invention

[0006] The purpose of the present invention is to solve the problems existing in the prior art and provide a method for preparing a high-temperature resistant thermal expansion epoxy resin foam material.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A method for preparing a high temperature resistant heat expansion epoxy resin foam material, comprising placing a heat expansion resin sheet into a mold, and then placing the mold containing the heat expansion resin sheet into a flat vulcanizer, and performing a curing and foaming treatment to obtain the high temperature resistant heat expansion epoxy resin foam material;

[0009] The preparation process of the heat-expandable resin sheet is as follows: bismaleimide (BMI), diallyl bisphenol A (BBA), heat-expandable microspheres, epoxy resin (EP) and 4,4-diaminodiphenyl sulfone (DDS) are stirred at 130-150°C for 2-4 hours to obtain a mixed resin liquid, the mixed resin liquid is placed in a mold, hot-pressed at 60-90°C and 0.1MPa, and then cooled to room temperature to form a heat-expandable resin sheet with a thickness of 1-5mm;

[0010] The mass ratio of bismaleimide to o-diallyl bisphenol A is 4:1-3, and the mass ratio of o-diallyl bisphenol A, thermal expansion microspheres, epoxy resin and 4,4-diaminodiphenyl sulfone is 1-3:3-10:20:10-15.

[0011] As the preferred technical solution:

[0012] The preparation method of the high temperature resistant heat expansion epoxy resin foam material as described above, the pore diameter of the high temperature resistant heat expansion epoxy resin foam material is 300~600μm, and the glass transition temperature is 228~268℃; the compressive strength of the high temperature resistant heat expansion epoxy resin foam material at room temperature is 5.5~9MPa, and the compressive strength at 180℃ is 1.3~6MPa.

[0013] In the method for preparing a high temperature resistant heat-expandable epoxy resin foam material as described above, the particle size of the heat-expandable microspheres is 15-45 μm.

[0014] The preparation method of the high temperature resistant heat expansion epoxy resin foam material as described above, the curing and foaming process is: first treat at 170~190℃ for 0.5~2h, then treat at 200~210℃ for 1~2h, and finally treat at 220~240℃ for 1~2h.

[0015] In the method for preparing a high temperature resistant heat-expandable epoxy resin foam material as described above, the expansion force of the heat-expandable resin sheet is 0.3-0.5 MPa.

[0016] Principle of the invention:

[0017] In the preparation process of the heat-expandable resin sheet, due to the electron-withdrawing effect of the carbonyl group in the molecular structure of BMI, its C=C bond is an electron-deficient double bond, and firstly undergoes diene addition with the allyl compound BBA to generate an intermediate. At a temperature of 130-150° C., the double bond of BMI undergoes a Diels-Adler reaction with the intermediate, that is, the anionic polyimide oligomer reacts with the diene reaction intermediate to generate a high cross-linking density polymer with a ladder structure (the mass ratio of BMI to BBA of the present invention is 4:3-4:1, which is converted into a molar ratio of 2:1.74-3.45:1, and the equivalent ratio of the groups participating in the reaction is 1:1, so it can be ensured that there are remaining maleimide groups after the reaction of BMI and BBA for subsequent reaction with the intermediate); in the process of curing and foaming the heat-expandable resin sheet, the high cross-linking density polymer with a ladder structure generated above reacts with DDS through a Michael addition reaction to generate a copolymer, and the active hydrogen on the amino group of the copolymer undergoes a ring-opening reaction with the epoxy group to form a cross-linked network structure. Due to the high cross-linking and network structure characteristics of the molecular structure, the mechanical properties and heat resistance of the foam material are significantly improved. It has a high glass transition temperature, which improves the mechanical properties under room temperature conditions and can maintain good mechanical properties when the external ambient temperature is high. It solves the problem of serious loss of mechanical properties of traditional epoxy foam as the temperature rises.

[0018] Beneficial effects:

[0019] (1) The present invention forms a copolymer by Michael addition reaction of a high cross-linking density polymer with a ladder structure and DDS. The active hydrogen on the amino group of the copolymer undergoes a ring-opening reaction with the epoxy group to form a cross-linking network structure, thereby greatly improving its heat resistance.

[0020] (2) The high temperature resistant heat expansion epoxy resin foam material prepared by the present invention has a small attenuation of mechanical properties under room temperature and high temperature conditions. DETAILED DESCRIPTION

[0021] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0022] The testing methods of the relevant performance indicators in the following embodiments and comparative examples are as follows:

[0023] First, the high temperature resistant heat expansion epoxy resin foam material was made into two cylindrical samples A and B with a height of 28mm and a radius of 30mm. Then, according to the ASTM-D1621 standard, a universal testing machine (manufacturer: Meters, model: 30KN) and an environmental chamber were used to test the compressive strength of samples A and B respectively. The test process is as follows:

[0024] Compression strength at 25°C: Sample A was placed in an environmental chamber at 25°C to test the compression strength of sample A; the inlet force of the universal testing machine was set to 30N and the descending rate was 2.8mm / min;

[0025] Compression strength at 180°C: Sample B was placed in an environmental chamber at 180°C to test the compression strength of Sample B; wherein the inlet force of the universal testing machine was set to 30N and the descending rate was 2.8mm / min.

[0026] Glass transition temperature (Tg): The high temperature resistant heat expansion epoxy resin foam material prepared in each embodiment is first made into a specimen with a size of 60 mm×15 mm×3 mm, and then a dynamic thermomechanical analyzer (DMA) (manufacturer: TAinstrument, model: Model Q800) is used to perform dynamic thermomechanical performance analysis on the specimen to obtain Tg; wherein, the test process adopts a double cantilever beam mode, the frequency is 1 Hz, the heating rate is 3°C / min, and the temperature is 25~320°C.

[0027] Expansion force: A universal testing machine (manufacturer: Meters, model: 30KN) and an environmental chamber were used to test the thermal expansion resin sheet. During the test, the thermal self-expanding resin sheet was first placed in a 100×100×10mm mold, and then the temperature of the environmental chamber was set to 180°C. After the temperature stabilized, the mold containing the self-expanding resin was placed in the universal testing machine and the pre-pressure of the testing machine was set to 300N. The maximum force during the process was taken, which was the expansion force of the thermal expansion resin sheet.

[0028] Example 1

[0029] A method for preparing a high temperature resistant thermal expansion epoxy resin foam material, the specific steps are as follows:

[0030] (1) Preparation of raw materials;

[0031] Bismaleimide: The manufacturer is Jiangsu Dongcai New Materials Co., Ltd., the brand is DFE929;

[0032] o-Diallyl bisphenol A: The manufacturer is Laizhou Laiyu Chemical Co., Ltd.;

[0033] Thermal expansion microspheres: The manufacturer is Matsumoto Oil and Fat Pharmaceutical Co., Ltd., the brand is F-260D, and the average particle size is 15 μm;

[0034] Epoxy resin: The manufacturer is Guangzhou Yihuishenghua Co., Ltd., brand number is 638S;

[0035] 4,4-Diaminodiphenyl sulfone: The manufacturer is Guangzhou Yihuisheng Chemical Co., Ltd.;

[0036] (2) Preparing a thermal expansion resin sheet;

[0037] Stirring bismaleimide, o-diallyl bisphenol A, heat-expandable microspheres, epoxy resin and 4,4-diaminodiphenyl sulfone at 130° C. for 2 hours to obtain a mixed resin liquid, placing the mixed resin liquid in a mold, hot pressing at 70° C. and 0.1 MPa, and then cooling to room temperature to form a heat-expandable resin sheet with a thickness of 1 mm; wherein the mass ratio of bismaleimide, o-diallyl bisphenol A, heat-expandable microspheres, epoxy resin and 4,4-diaminodiphenyl sulfone is 4:3:3:20:10;

[0038] The expansion force of the obtained heat-expandable resin sheet is 0.3MPa;

[0039] (3) Preparation of high temperature resistant epoxy resin foam material;

[0040] A heat-expandable resin sheet is laid in the mold, and then the mold with the heat-expandable resin sheet is placed in a flat vulcanizer. It is first hot-pressed at 170°C for 0.5 h, then hot-pressed at 200°C for 1 h, and finally hot-pressed at 220°C for 1 h to obtain a high-temperature resistant epoxy resin foam material with a thickness of 5 mm.

[0041] The average pore size of the pores in the finally obtained high temperature resistant heat expansion epoxy resin foam material is 300 μm, and the glass transition temperature is 228°C; the compressive strength of the high temperature resistant heat expansion epoxy resin foam material is 5.5 MPa at 25°C, and the compressive strength at 180°C is 2.8 MPa.

[0042] Example 2

[0043] A method for preparing a high temperature resistant heat expandable epoxy resin foam material is basically the same as that in Example 1, except that in step (2), the mass ratio of bismaleimide, o-diallyl bisphenol A, heat expandable microspheres, epoxy resin and 4,4-diaminodiphenyl sulfone is 2:1:3:20:10.

[0044] The expansion force of the obtained heat-expandable resin sheet is 0.3MPa;

[0045] The average pore size of the pores in the finally obtained high temperature resistant heat expansion epoxy resin foam material is 300 μm, and the glass transition temperature is 235°C; the compressive strength of the high temperature resistant heat expansion epoxy resin foam material is 6 MPa at 25°C, and the compressive strength at 180°C is 3.1 MPa.

[0046] Example 3

[0047] A method for preparing a high temperature resistant heat expandable epoxy resin foam material is basically the same as that in Example 1, except that in step (2), the mass ratio of bismaleimide, o-diallyl bisphenol A, heat expandable microspheres, epoxy resin and 4,4-diaminodiphenyl sulfone is 3:1:3:20:10.

[0048] The expansion force of the obtained heat-expandable resin sheet is 0.3MPa;

[0049] The average pore size of the pores in the finally obtained high temperature resistant heat expansion epoxy resin foam material is 300 μm, and the glass transition temperature is 253°C; the compressive strength of the high temperature resistant heat expansion epoxy resin foam material is 7.3 MPa at 25°C, and the compressive strength at 180°C is 3.7 MPa.

[0050] Example 4

[0051] A method for preparing a high temperature resistant heat expandable epoxy resin foam material is basically the same as that in Example 1, except that in step (2), the mass ratio of bismaleimide, o-diallyl bisphenol A, heat expandable microspheres, epoxy resin and 4,4-diaminodiphenyl sulfone is 4:1:3:20:10.

[0052] The expansion force of the obtained heat-expandable resin sheet is 0.3MPa;

[0053] The average pore size of the pores in the finally obtained high temperature resistant heat expansion epoxy resin foam material is 300 μm, and the glass transition temperature is 261°C; the compressive strength of the high temperature resistant heat expansion epoxy resin foam material is 8 MPa at 25°C, and the compressive strength at 180°C is 4.3 MPa.

[0054] Example 5

[0055] A method for preparing a high temperature resistant thermal expansion epoxy resin foam material, the specific steps are as follows:

[0056] (1) Preparation of raw materials;

[0057] Bismaleimide: The manufacturer is Jiangsu Dongcai New Materials Co., Ltd., the brand is DFE929;

[0058] o-Diallyl bisphenol A: The manufacturer is Laizhou Laiyu Chemical Co., Ltd.;

[0059] Thermal expansion microspheres: The manufacturer is Matsumoto Oil and Fat Pharmaceutical Co., Ltd., the brand is F-230, and the average particle size is 45 μm;

[0060] Epoxy resin: The manufacturer is Guangzhou Yihuishenghua Co., Ltd., brand number is 638S;

[0061] 4,4-Diaminodiphenyl sulfone: The manufacturer is Guangzhou Yihuisheng Chemical Co., Ltd.;

[0062] (2) Preparing a thermal expansion resin sheet;

[0063] Stirring bismaleimide, o-diallyl bisphenol A, heat-expandable microspheres, epoxy resin and 4,4-diaminodiphenyl sulfone at 130° C. for 2 hours to obtain a mixed resin liquid, placing the mixed resin liquid in a mold, hot pressing at 70° C. and 0.1 MPa, and then cooling to room temperature to form a heat-expandable resin sheet with a thickness of 1 mm; wherein the mass ratio of bismaleimide, o-diallyl bisphenol A, heat-expandable microspheres, epoxy resin and 4,4-diaminodiphenyl sulfone is 4:1:3:20:10;

[0064] The expansion force of the obtained heat-expandable resin sheet is 0.35MPa;

[0065] (3) Preparation of high temperature resistant epoxy resin foam material;

[0066] A heat-expandable resin sheet is laid in the mold, and then the mold with the heat-expandable resin sheet is placed in a flat vulcanizer. It is first hot-pressed at 170°C for 0.5 h, then hot-pressed at 200°C for 1 h, and finally hot-pressed at 220°C for 1 h to obtain a high-temperature resistant epoxy resin foam material with a thickness of 5 mm.

[0067] The average pore size of the pores in the finally obtained high temperature resistant heat expansion epoxy resin foam material is 400 μm, and the glass transition temperature is 263°C; the compressive strength of the high temperature resistant heat expansion epoxy resin foam material is 8.5 MPa at 25°C, and the compressive strength at 180°C is 4.5 MPa.

[0068] Example 6

[0069] A method for preparing a high temperature resistant heat expandable epoxy resin foam material is basically the same as that in Example 5, except that: the heat expandable microspheres in steps (1) and (2) are replaced with heat expandable microspheres of equal mass (manufacturer: American Polychem, brand: 220DU30, average particle size: 30 μm);

[0070] The expansion force of the obtained heat-expandable resin sheet was 0.4 MPa.

[0071] The average pore size of the pores in the finally obtained high temperature resistant heat expansion epoxy resin foam material is 600 μm, and the glass transition temperature is 241°C; the compressive strength of the high temperature resistant heat expansion epoxy resin foam material is 6.2 MPa at 25°C, and the compressive strength at 180°C is 2.1 MPa.

[0072] Example 7

[0073] A method for preparing a high temperature resistant heat expandable epoxy resin foam material is basically the same as that in Example 5, except that: in step (2), the mass ratio of bismaleimide, o-diallyl bisphenol A, heat expandable microspheres, epoxy resin and 4,4-diaminodiphenyl sulfone is 4:1:5:20:10;

[0074] The expansion force of the obtained heat-expandable resin sheet was 0.37 MPa.

[0075] The average pore size of the pores in the finally obtained high temperature resistant heat expansion epoxy resin foam material is 380 μm, and the glass transition temperature is 263°C; the compressive strength of the high temperature resistant heat expansion epoxy resin foam material is 8.5 MPa at 25°C, and the compressive strength at 180°C is 4.5 MPa.

[0076] Example 8

[0077] A method for preparing a high temperature resistant heat expandable epoxy resin foam material is basically the same as that in Example 5, except that: in step (2), the mass ratio of bismaleimide, o-diallyl bisphenol A, heat expandable microspheres, epoxy resin and 4,4-diaminodiphenyl sulfone is 4:1:7:20:10;

[0078] The expansion force of the obtained heat-expandable resin sheet was 0.42 MPa.

[0079] The average pore size of the pores in the finally obtained high temperature resistant heat expansion epoxy resin foam material is 340 μm, and the glass transition temperature is 252°C; the compressive strength of the high temperature resistant heat expansion epoxy resin foam material is 7.2 MPa at 25°C, and the compressive strength at 180°C is 3.8 MPa.

[0080] Example 9

[0081] A method for preparing a high temperature resistant heat expandable epoxy resin foam material is basically the same as that in Example 5, except that: in step (2), the mass ratio of bismaleimide, o-diallyl bisphenol A, heat expandable microspheres, epoxy resin and 4,4-diaminodiphenyl sulfone is 4:1:10:20:10;

[0082] The expansion force of the obtained heat-expandable resin sheet was 0.5 MPa.

[0083] The average pore size of the pores in the finally obtained high temperature resistant heat expansion epoxy resin foam material is 300 μm, and the glass transition temperature is 241°C; the compressive strength of the high temperature resistant heat expansion epoxy resin foam material is 6.3 MPa at 25°C, and the compressive strength at 180°C is 4.6 MPa.

[0084] Example 10

[0085] A method for preparing a high temperature resistant heat expandable epoxy resin foam material is basically the same as that in Example 5, except that in step (2), the mass ratio of bismaleimide, o-diallyl bisphenol A, heat expandable microspheres, epoxy resin and 4,4-diaminodiphenyl sulfone is 4:2:3:20:10.

[0086] The expansion force of the obtained heat-expandable resin sheet is 0.35MPa;

[0087] The average pore size of the pores in the finally obtained high temperature resistant heat expansion epoxy resin foam material is 400 μm, and the glass transition temperature is 263°C; the compressive strength of the high temperature resistant heat expansion epoxy resin foam material is 8.4 MPa at 25°C, and the compressive strength at 180°C is 4.6 MPa.

[0088] Embodiment 11

[0089] A method for preparing a high temperature resistant heat expandable epoxy resin foam material is basically the same as that in Example 5, except that in step (2), the mass ratio of bismaleimide, o-diallyl bisphenol A, heat expandable microspheres, epoxy resin and 4,4-diaminodiphenyl sulfone is 4:3:3:20:10.

[0090] The expansion force of the obtained heat-expandable resin sheet is 0.35MPa;

[0091] The average pore size of the pores in the finally obtained high temperature resistant heat expansion epoxy resin foam material is 400 μm, and the glass transition temperature is 251°C; the compressive strength of the high temperature resistant heat expansion epoxy resin foam material is 7.1 MPa at 25°C, and the compressive strength at 180°C is 3.1 MPa.

[0092] Example 12

[0093] A method for preparing a high temperature resistant heat expandable epoxy resin foam material is basically the same as that in Example 5, except that in step (2), the mass ratio of bismaleimide, o-diallyl bisphenol A, heat expandable microspheres, epoxy resin and 4,4-diaminodiphenyl sulfone is 4:1:3:20:12.

[0094] The expansion force of the obtained heat-expandable resin sheet is 0.35MPa;

[0095] The average pore size of the pores in the finally obtained high temperature resistant heat expansion epoxy resin foam material is 400 μm, and the glass transition temperature is 265°C; the compressive strength of the high temperature resistant heat expansion epoxy resin foam material is 8.5 MPa at 25°C, and the compressive strength at 180°C is 5.1 MPa.

[0096] Example 13

[0097] A method for preparing a high temperature resistant heat expandable epoxy resin foam material is basically the same as that in Example 5, except that in step (2), the mass ratio of bismaleimide, o-diallyl bisphenol A, heat expandable microspheres, epoxy resin and 4,4-diaminodiphenyl sulfone is 4:1:3:20:15.

[0098] The expansion force of the obtained heat-expandable resin sheet is 0.35MPa;

[0099] The average pore size of the pores in the finally obtained high temperature resistant heat expansion epoxy resin foam material is 400 μm, and the glass transition temperature is 267°C; the compressive strength of the high temperature resistant heat expansion epoxy resin foam material is 8.7 MPa at 25°C, and the compressive strength at 180°C is 5.3 MPa.

[0100] Embodiment 14

[0101] A method for preparing a high temperature resistant heat expandable epoxy resin foam material is basically the same as that in Example 5, except that the first hot pressing treatment temperature in step (3) is 180°C.

[0102] The average pore size of the pores in the finally obtained high temperature resistant heat expansion epoxy resin foam material is 500 μm, and the glass transition temperature is 259°C; the compressive strength of the high temperature resistant heat expansion epoxy resin foam material is 8.4 MPa at 25°C, and the compressive strength at 180°C is 4.6 MPa.

[0103] Embodiment 15

[0104] A method for preparing a high temperature resistant heat expandable epoxy resin foam material is basically the same as that in Example 5, except that the first hot pressing treatment temperature in step (3) is 190°C.

[0105] The average pore size of the pores in the finally obtained high temperature resistant heat expansion epoxy resin foam material is 600 μm, and the glass transition temperature is 259°C; the compressive strength of the high temperature resistant heat expansion epoxy resin foam material is 8.4 MPa at 25°C, and the compressive strength at 180°C is 3.6 MPa.

[0106] Example 16

[0107] A method for preparing a high temperature resistant heat expandable epoxy resin foam material is basically the same as that in Example 5, except that the first hot pressing treatment in step (3) lasts for 1 hour.

[0108] The average pore size of the pores in the finally obtained high temperature resistant heat expansion epoxy resin foam material is 400 μm, and the glass transition temperature is 263°C; the compressive strength of the high temperature resistant heat expansion epoxy resin foam material is 8.5 MPa at 25°C, and the compressive strength at 180°C is 4.5 MPa.

[0109] Embodiment 17

[0110] A method for preparing a high temperature resistant heat expandable epoxy resin foam material is basically the same as that in Example 5, except that the first hot pressing treatment in step (3) lasts for 2 hours.

[0111] The average pore size of the pores in the finally obtained high temperature resistant heat expansion epoxy resin foam material is 400 μm, and the glass transition temperature is 263°C; the compressive strength of the high temperature resistant heat expansion epoxy resin foam material is 8.5 MPa at 25°C, and the compressive strength at 180°C is 4.5 MPa.

[0112] Embodiment 18

[0113] A method for preparing a high temperature resistant heat expandable epoxy resin foam material is basically the same as that in Example 5, except that the second hot pressing treatment temperature in step (3) is 210°C.

[0114] The average pore size of the pores in the finally obtained high temperature resistant heat expansion epoxy resin foam material is 400 μm, and the glass transition temperature is 266°C; the compressive strength of the high temperature resistant heat expansion epoxy resin foam material is 8.7 MPa at 25°C, and the compressive strength at 180°C is 5.3 MPa.

[0115] Embodiment 19

[0116] A method for preparing a high temperature resistant heat expandable epoxy resin foam material is basically the same as that in Example 5, except that the second hot pressing treatment temperature in step (3) is 205°C.

[0117] The average pore size of the pores in the finally obtained high temperature resistant heat expansion epoxy resin foam material is 400 μm, and the glass transition temperature is 265°C; the compressive strength of the high temperature resistant heat expansion epoxy resin foam material is 8.6 MPa at 25°C, and the compressive strength at 180°C is 5.2 MPa.

[0118] Embodiment 20

[0119] A method for preparing a high temperature resistant heat expandable epoxy resin foam material is basically the same as that in Example 5, except that the second hot pressing treatment in step (3) lasts for 1.5 hours.

[0120] The average pore size of the pores in the finally obtained high temperature resistant heat expansion epoxy resin foam material is 400 μm, and the glass transition temperature is 263°C; the compressive strength of the high temperature resistant heat expansion epoxy resin foam material is 8.4 MPa at 25°C, and the compressive strength at 180°C is 5.1 MPa.

[0121] Embodiment 21

[0122] A method for preparing a high temperature resistant heat expandable epoxy resin foam material is basically the same as that in Example 5, except that the second hot pressing treatment in step (3) lasts for 2 hours.

[0123] The average pore size of the pores in the finally obtained high temperature resistant heat expansion epoxy resin foam material is 400 μm, and the glass transition temperature is 264°C; the compressive strength of the high temperature resistant heat expansion epoxy resin foam material is 8.6 MPa at 25°C, and the compressive strength at 180°C is 5.2 MPa.

[0124] Embodiment 22

[0125] A method for preparing a high temperature resistant heat expandable epoxy resin foam material is basically the same as that in Example 5, except that the temperature of the third hot pressing treatment in step (3) is 230°C.

[0126] The average pore size of the pores in the finally obtained high temperature resistant heat expansion epoxy resin foam material is 400 μm, and the glass transition temperature is 266°C; the compressive strength of the high temperature resistant heat expansion epoxy resin foam material is 8.7 MPa at 25°C, and the compressive strength at 180°C is 5.3 MPa.

[0127] Embodiment 23

[0128] A method for preparing a high temperature resistant heat expandable epoxy resin foam material is basically the same as that in Example 5, except that the temperature of the third hot pressing treatment in step (3) is 240°C.

[0129] The average pore size of the pores in the finally obtained high temperature resistant heat expansion epoxy resin foam material is 400 μm, and the glass transition temperature is 268°C; the compressive strength of the high temperature resistant heat expansion epoxy resin foam material is 9 MPa at 25°C, and the compressive strength at 180°C is 6 MPa.

[0130] Embodiment 24

[0131] A method for preparing a high temperature resistant heat expandable epoxy resin foam material is basically the same as that in Example 5, except that the duration of the third hot pressing treatment in step (3) is 1.5 hours.

[0132] The average pore size of the pores in the finally obtained high temperature resistant heat expansion epoxy resin foam material is 400 μm, and the glass transition temperature is 265°C; the compressive strength of the high temperature resistant heat expansion epoxy resin foam material is 8.7 MPa at 25°C, and the compressive strength at 180°C is 5.2 MPa.

[0133] Embodiment 25

[0134] A method for preparing a high temperature resistant heat expandable epoxy resin foam material is basically the same as that in Example 5, except that the third hot pressing treatment in step (3) lasts for 2 hours.

[0135] The average pore size of the pores in the finally obtained high temperature resistant heat expansion epoxy resin foam material is 400 μm, and the glass transition temperature is 267°C; the compressive strength of the high temperature resistant heat expansion epoxy resin foam material is 8.9 MPa at 25°C, and the compressive strength at 180°C is 5.5 MPa.

[0136] Embodiment 26

[0137] A method for preparing a high temperature resistant thermal expansion epoxy resin foam material, the specific steps are as follows:

[0138] (1) Preparation of raw materials;

[0139] Bismaleimide: The manufacturer is Jiangsu Dongcai New Materials Co., Ltd., the brand is DFE929;

[0140] o-Diallyl bisphenol A: The manufacturer is Laizhou Laiyu Chemical Co., Ltd.;

[0141] Thermal expansion microspheres: The manufacturer is Matsumoto Oil and Fat Pharmaceutical Co., Ltd., the brand is F-230, and the average particle size is 45 μm;

[0142] Epoxy resin: The manufacturer is Guangzhou Yihuishenghua Co., Ltd., brand number is 638S;

[0143] 4,4-Diaminodiphenyl sulfone: The manufacturer is Guangzhou Yihuisheng Chemical Co., Ltd.;

[0144] (2) Preparing a thermal expansion resin sheet;

[0145] Stirring bismaleimide, o-diallyl bisphenol A, heat-expandable microspheres, epoxy resin and 4,4-diaminodiphenyl sulfone at 140° C. for 4 hours to obtain a mixed resin liquid, placing the mixed resin liquid in a mold, hot pressing at 60° C. and 0.1 MPa, and then cooling to room temperature to form a heat-expandable resin sheet with a thickness of 3 mm; wherein the mass ratio of bismaleimide, o-diallyl bisphenol A, heat-expandable microspheres, epoxy resin and 4,4-diaminodiphenyl sulfone is 4:1:3:20:10;

[0146] The expansion force of the obtained heat-expandable resin sheet is 0.35MPa;

[0147] (3) Preparation of high temperature resistant epoxy resin foam material;

[0148] A heat-expandable resin sheet is laid in the mold, and then the mold with the heat-expandable resin sheet is placed in a flat vulcanizer. It is first hot-pressed at 170°C for 0.5h, then hot-pressed at 200°C for 1h, and finally hot-pressed at 220°C for 1h to obtain a high-temperature resistant epoxy resin foam material with a thickness of 15mm.

[0149] The average pore size of the pores in the finally obtained high temperature resistant heat expansion epoxy resin foam material is 400 μm, and the glass transition temperature is 263°C; the compressive strength of the high temperature resistant heat expansion epoxy resin foam material is 8.5 MPa at 25°C, and the compressive strength at 180°C is 4.5 MPa.

[0150] Embodiment 27

[0151] A method for preparing a high temperature resistant thermal expansion epoxy resin foam material, the specific steps are as follows:

[0152] (1) Preparation of raw materials;

[0153] Bismaleimide: The manufacturer is Jiangsu Dongcai New Materials Co., Ltd., the brand is DFE929;

[0154] o-Diallyl bisphenol A: The manufacturer is Laizhou Laiyu Chemical Co., Ltd.;

[0155] Thermal expansion microspheres: The manufacturer is Matsumoto Oil and Fat Pharmaceutical Co., Ltd., the brand is F-230, and the average particle size is 45 μm;

[0156] Epoxy resin: The manufacturer is Guangzhou Yihuishenghua Co., Ltd., brand number is 638S;

[0157] 4,4-Diaminodiphenyl sulfone: The manufacturer is Guangzhou Yihuisheng Chemical Co., Ltd.;

[0158] (2) Preparing a thermal expansion resin sheet;

[0159] Stirring bismaleimide, o-diallyl bisphenol A, heat-expandable microspheres, epoxy resin and 4,4-diaminodiphenyl sulfone at 150° C. for 3 hours to obtain a mixed resin liquid, placing the mixed resin liquid in a mold, hot pressing at 90° C. and 0.1 MPa, and then cooling to room temperature to form a heat-expandable resin sheet with a thickness of 5 mm; wherein the mass ratio of bismaleimide, o-diallyl bisphenol A, heat-expandable microspheres, epoxy resin and 4,4-diaminodiphenyl sulfone is 4:1:3:20:10;

[0160] The expansion force of the obtained heat-expandable resin sheet is 0.35MPa;

[0161] (3) Preparation of high temperature resistant epoxy resin foam material;

[0162] A heat-expandable resin sheet is laid in the mold, and then the mold with the heat-expandable resin sheet is placed in a flat vulcanizer. It is first hot-pressed at 170°C for 0.5h, then hot-pressed at 200°C for 1h, and finally hot-pressed at 220°C for 1h to obtain a high-temperature resistant epoxy resin foam material with a thickness of 25mm.

[0163] The average pore size of the pores in the finally obtained high temperature resistant heat expansion epoxy resin foam material is 400 μm, and the glass transition temperature is 263°C; the compressive strength of the high temperature resistant heat expansion epoxy resin foam material is 8.5 MPa at 25°C, and the compressive strength at 180°C is 4.5 MPa.

Claims

1. A method for preparing a high temperature resistant thermal expansion epoxy resin foam material, characterized in that: Putting a heat-expandable resin sheet into a mold, then putting the mold containing the heat-expandable resin sheet into a flat vulcanizer, and performing a curing and foaming treatment to obtain a high-temperature resistant heat-expandable epoxy resin foam material; The preparation process of the heat-expandable resin sheet is as follows: bismaleimide, o-diallyl bisphenol A, heat-expandable microspheres, epoxy resin and 4,4-diaminodiphenyl sulfone are stirred at 130-150° C. for 2-4 hours to obtain a mixed resin liquid, the mixed resin liquid is placed in a mold, hot-pressed at 60-90° C. and 0.1 MPa, and then cooled to room temperature to form a heat-expandable resin sheet with a thickness of 1-5 mm; The mass ratio of bismaleimide to o-diallyl bisphenol A is 4:1-3, and the mass ratio of o-diallyl bisphenol A, thermal expansion microspheres, epoxy resin and 4,4-diaminodiphenyl sulfone is 1-3:3-10:20:10-15; The pore diameter of the high temperature resistant heat expansion epoxy resin foam material is 300-600 μm, and the glass transition temperature is 228-268° C.; the compressive strength of the high temperature resistant heat expansion epoxy resin foam material at room temperature is 5.5-9 MPa, and the compressive strength at 180° C. is 1.3-6 MPa.

2. The method for preparing a high temperature resistant heat expansion epoxy resin foam material according to claim 1, characterized in that: The particle size of the heat-expandable microspheres is 15 to 45 μm.

3. The method for preparing a high temperature resistant heat expansion epoxy resin foam material according to claim 2, characterized in that: The curing and foaming treatment process is: first treat at 170-190°C for 0.5-2h, then treat at 200-210°C for 1-2h, and finally treat at 220-240°C for 1-2h.

4. The method for preparing a high temperature resistant heat expansion epoxy resin foam material according to claim 1, characterized in that: The expansion force of the heat-expandable resin sheet is 0.3 to 0.5 MPa.