High-temperature-resistant low-dielectric epoxy resin prepreg as well as preparation method and application thereof

Abstract

The invention discloses a high-temperature-resistant low-dielectric epoxy resin prepreg as well as a preparation method and application thereof. Researches show that by introducing proper groups, a resin matrix can be endowed with good high-temperature resistance, and the glass-transition temperature of an epoxy resin system can be synergistically improved. Moreover, regular and symmetrical groups are introduced into a molecular main chain through molecular structure design, so that the polarity and dipole moment of the molecular chain can be reduced, and the dielectric property of the material is improved. Besides, by reasonably controlling the raw material ratio and the modification process route, the high-temperature-resistant low-dielectric epoxy resin disclosed by the invention has a chemical adhesion effect, the viscosity of a prepreg resin system can be improved, and the fluidity and permeability of a resin matrix in the molding process of the prepreg are ensured.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite materials, and particularly relates to a high-temperature resistant and low-dielectric epoxy resin prepreg, a preparation method thereof, and an application thereof. Background Art

[0002] With the rapid development of high-tech fields such as high-frequency communication, the demand for high-temperature resistant and low-dielectric epoxy resin-based composite materials is increasing day by day. In some special application scenarios, traditional epoxy prepregs have defects of poor high-temperature resistance and insufficient dielectric properties, resulting in easy softening and decomposition at high temperatures, leading to performance degradation, as well as signal delay and energy loss, and it is difficult to meet the stringent requirements of high-tech industries for materials. Therefore, the development of epoxy resin-based prepregs with both high-temperature resistance and low-dielectric properties has become a current research hotspot.

[0003] Chinese Patent Application CN104726045A uses a matrix epoxy resin containing heat-resistant groups such as aromatic rings, alicyclic rings, and heterocyclic rings on the molecular chain, and the heat resistance of the product reaches 250 °C. However, the epoxy resin prepared by this method has a relatively high dielectric property due to the addition of alumina filler. In addition, Chinese Patent Application CN119217811A introduces cage-type polyhedral oligomeric silsesquioxane resin (POSS), and cooperates with the use of inorganic fillers such as dicyclopentadiene phenol-modified epoxy resin and silica powder in a specific proportion to synergistically improve the dielectric property and heat resistance of the material. However, the addition of a large amount of fillers is not easy to disperse evenly, resulting in poor film-forming properties of the resin system and difficulty in meeting the process characteristics during the preparation of prepregs.

[0004] Therefore, there is an urgent need to develop an epoxy resin-based prepreg with high-temperature resistance, low dielectric property, and capable of meeting the prepreg preparation process. Summary of the Invention

[0005] To solve at least some of the above technical problems in the prior art, the present invention provides a high-temperature resistant and low-dielectric epoxy resin prepreg, a preparation method thereof, and an application thereof. Specifically, the present invention includes the following contents.

[0006] In a first aspect of the present invention, a preparation method of a high-temperature resistant and low-dielectric epoxy resin prepreg is provided, which includes the following steps:

[0007] (1) In the presence of a first catalyst, reacting an epoxy resin with a diisocyanate compound containing an aromatic group at 120-160 °C for 2-4 h, adding a bisphenol A poly(phenylene oxide), and continuing to react for 1-3 h in the presence of a second catalyst to obtain a high-temperature resistant and low-dielectric epoxy resin, wherein the molar ratio of the epoxy resin to the diisocyanate compound is (3-6):1;

[0008] (2) Mix the high-temperature resistant and low-dielectric epoxy resin with a liquid epoxy resin and a latent curing system to obtain a resin system for prepreg, wherein the high-temperature resistant and low-dielectric epoxy resin is 100 parts by weight, the liquid epoxy resin is 20 - 50 parts by weight, and the latent curing system is 6 - 12 parts by weight;

[0009] (3) Prepare the resin system for prepreg into a film, and compound it with fibers to obtain the high-temperature resistant and low-dielectric epoxy resin prepreg.

[0010] In certain embodiments, according to the preparation method of the present invention, wherein in step (1), the dosage of the first catalyst is 0.1 - 1% of the sum of the masses of the epoxy resin and the diisocyanate compound, the dosage of the second catalyst is 0.1 - 1% of the sum of the masses of the epoxy resin and the diisocyanate compound, and the dosage of the bisphenol-terminated polyphenylene ether is 5 - 15% of the sum of the masses of the epoxy resin and the diisocyanate compound.

[0011] In certain embodiments, according to the preparation method of the present invention, wherein the first catalyst includes at least one of imidazole, imidazole derivatives, Lewis acids, and base complexes.

[0012] In certain embodiments, according to the preparation method of the present invention, wherein the epoxy resin includes at least one of bisphenol A glycidyl ether, bisphenol F glycidyl ether, bisphenol AD glycidyl ether, liquid phenolic epoxy resin, and alicyclic epoxy resin.

[0013] In certain embodiments, according to the preparation method of the present invention, wherein the aromatic group-containing diisocyanate compound includes at least one of 1,5-naphthalene diisocyanate, dimethylbiphenyl diisocyanate, and p-phenylene diisocyanate.

[0014] In certain embodiments, according to the preparation method of the present invention, wherein the second catalyst includes at least one of triphenylphosphine and tetramethylammonium hydroxide.

[0015] In certain embodiments, according to the preparation method of the present invention, wherein the latent curing system includes at least one of dicyandiamide, modified dicyandiamide, and urea derivatives.

[0016] In certain embodiments, according to the preparation method of the present invention, wherein the fibers include at least one of E-glass fiber, high-strength glass fiber, and quartz fiber.

[0017] In the second aspect of the present invention, there is provided a high-temperature resistant and low-dielectric epoxy resin prepreg obtained by the preparation method described in the first aspect of the present invention.

[0018] In a third aspect of the present invention, there is provided an application of the high-temperature resistant and low-dielectric epoxy resin prepreg according to the second aspect of the present invention in high-frequency communication devices.

[0019] Through research, the present invention has found that diisocyanates containing naphthalene rings, biphenyls or p-phenylene groups can endow the resin matrix with good high-temperature resistance, and polyphenylene ethers can synergistically increase the glass transition temperature of the epoxy resin system. Moreover, through molecular structure design, the present invention introduces regular and symmetrical naphthalene rings, biphenyls or p-phenylene groups into the molecular main chain, which can reduce the polarity and dipole moment of the molecular chain, improve the dielectric properties of the material, and achieve the effect of synergistically improving the dielectric properties of the epoxy resin with polyphenylene ether.

[0020] In addition, by reasonably controlling the raw material ratio and the modification process route, the present invention uses diisocyanates containing aromatic groups as linear chain extenders of epoxy resins, which can increase the distance between rigid crosslinking points in the cured crosslinked network, endow the resin system with toughness and increase the initial viscosity of the resin matrix, and further introduce polyphenylene ether chain segments to improve the flexibility of the resin matrix and increase the viscosity of the resin system. Therefore, the high-temperature resistant and low-dielectric epoxy resin of the present invention has a chemical adhesion effect, can increase the viscosity of the prepreg resin system, and ensures the fluidity and permeability of the resin matrix during the molding process of the prepreg. Detailed Embodiments

[0021] The various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be construed as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics, and embodiments of the present invention.

[0022] It should be understood that the terms used in the present invention are only for describing specific embodiments and are not intended to limit the present invention. In addition, for the numerical ranges in the present invention, it should be understood that the upper and lower limits of the range and each intermediate value therebetween are specifically disclosed. Intermediate values within any stated value or stated range and each smaller range between any other stated value or intermediate value within the stated range are also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0023] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0024] Preparation method

[0025] One aspect of the present invention provides a method for preparing a high temperature resistant and low dielectric epoxy resin prepreg.

[0026] In a preferred embodiment, the preparation method of the present invention comprises the following steps:

[0027] (1) In the presence of a first catalyst, an epoxy resin and a diisocyanate compound containing an aromatic group are reacted at 120-160° C. (e.g., 120, 125, 130, 135, 140, 145, 150, 155, 160° C.) for 2-4 h (e.g., 2, 2.2, 2.4, 2.6, 2.8, 3, 3.2, 3.4, 3.6, 3.8, 4 h), and a double-terminated hydroxyl polyphenylene ether is added. In the presence of a second catalyst, the reaction is continued for 1-3 hours (e.g., 1, 1.2, 1.4, 1.6, 1.8, 2, 2.2, 2.4, 2.6, 2.8, 3 hours) to obtain a high temperature resistant low dielectric epoxy resin, wherein the molar ratio of the epoxy resin to the diisocyanate compound is (3-6):1, e.g., 3:1, 3.5:1, 4:1, 4.5:1, 5:1, 5.5:1, 6:1;

[0028] (2) mixing the high temperature resistant low dielectric epoxy resin with a liquid epoxy resin and a latent curing system to obtain a prepreg resin system, wherein the high temperature resistant low dielectric epoxy resin is 100 parts by weight, the liquid epoxy resin is 20-50 parts by weight, and the latent curing system is 6-12 parts by weight;

[0029] (3) The prepreg is prepared into a film using a resin system, and compounded with fibers to obtain the high temperature resistant and low dielectric epoxy resin prepreg.

[0030] In order to improve the high-temperature resistance and dielectric properties of the high-temperature-resistant and low-dielectric epoxy resin prepreg, the molar ratio of the epoxy resin to the diisocyanate compound should not be too high or too low, and the dosage of the catalyst needs to be controlled within a suitable range. In the present invention, the molar ratio of the epoxy resin to the diisocyanate compound is (3 - 6):1, such as 3:1, 3.5:1, 4:1, 4.5:1, 5:1, 5.5:1, 6:1, or any ratio within the above range. The dosage of the first catalyst is 0.1 - 1% of the sum of the masses of the epoxy resin and the diisocyanate compound, such as 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%. In a preferred embodiment, the molar ratio of the epoxy resin to the diisocyanate compound is 6:1, and the dosage of the first catalyst is 1% of the sum of the masses of the epoxy resin and the diisocyanate compound. In another preferred embodiment, the molar ratio of the epoxy resin to the diisocyanate compound is 4.5:1, and the dosage of the first catalyst is 0.55% of the sum of the masses of the epoxy resin and the diisocyanate compound. In yet another preferred embodiment, the molar ratio of the epoxy resin to the diisocyanate compound is 3:1, and the dosage of the first catalyst is 0.1% of the sum of the masses of the epoxy resin and the diisocyanate compound.

[0031] In order to improve the high-temperature resistance and dielectric properties of the high-temperature-resistant and low-dielectric epoxy resin prepreg, the dosage of the bisphenol-A polyether should not be too high or too low, and the dosage of the catalyst needs to be controlled within a suitable range. If the dosage of the polyether is too large, the curing performance of the epoxy resin will tend to deteriorate. If the dosage of the polyether is too small, the dielectric properties of the prepreg will tend to deteriorate. In a preferred embodiment, the dosage of the bisphenol-A polyether is 5 - 15% of the sum of the masses of the epoxy resin and the diisocyanate compound, such as 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, or any value within the above range, and the dosage of the second catalyst is 1% of the sum of the masses of the epoxy resin and the diisocyanate compound, such as 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, or any value within the above range.

[0032] In a preferred embodiment, the amount of the bis-hydroxyl-terminated polyphenylene ether is 15% of the sum of the masses of the epoxy resin and the diisocyanate compound, and the amount of the second catalyst is 1% of the sum of the masses of the epoxy resin and the diisocyanate compound. In another preferred embodiment, the amount of the bis-hydroxyl-terminated polyphenylene ether is 10% of the sum of the masses of the epoxy resin and the diisocyanate compound, and the amount of the second catalyst is 0.55% of the sum of the masses of the epoxy resin and the diisocyanate compound. In yet another preferred embodiment, the amount of the bis-hydroxyl-terminated polyphenylene ether is 5% of the sum of the masses of the epoxy resin and the diisocyanate compound, and the amount of the second catalyst is 0.1% of the sum of the masses of the epoxy resin and the diisocyanate compound.

[0033] In the present invention, the first catalyst includes at least one of imidazole, imidazole derivatives, Lewis acid-base complexes. In a preferred embodiment, the first catalyst is imidazole. In another preferred embodiment, the first catalyst is an imidazole derivative. In yet another preferred embodiment, the first catalyst is a Lewis acid.

[0034] In the present invention, the epoxy resin includes at least one of bisphenol A glycidyl ether, bisphenol F glycidyl ether, bisphenol AD glycidyl ether, liquid phenolic epoxy resin, and alicyclic epoxy resin. In a preferred embodiment, the epoxy resin is bisphenol A glycidyl ether type epoxy resin. In another preferred embodiment, the epoxy resin is bisphenol F glycidyl ether type epoxy resin and bisphenol AD glycidyl ether type epoxy resin. In yet another preferred embodiment, the epoxy resin is liquid phenolic epoxy resin.

[0035] In the present invention, the aromatic group-containing diisocyanate compound includes at least one of 1,5-naphthalene diisocyanate, dimethylbiphenyl diisocyanate, and p-phenylene diisocyanate. In a preferred embodiment, the diisocyanate compound is 1,5-naphthalene diisocyanate. In another preferred embodiment, the diisocyanate compound is 1,5-naphthalene diisocyanate and dimethylbiphenyl diisocyanate. In yet another preferred embodiment, the diisocyanate compound is p-phenylene diisocyanate.

[0036] In the present invention, the second catalyst includes at least one of triphenylphosphine and tetramethylammonium hydroxide. In a preferred embodiment, the second catalyst is triphenylphosphine. In another preferred embodiment, the second catalyst is triphenylphosphine and tetramethylammonium hydroxide. In another preferred embodiment, the second catalyst is tetramethylammonium hydroxide.

[0037] In the present invention, the latent curing system includes at least one of dicyandiamide, modified dicyandiamide, and urea derivatives. In a preferred embodiment, the latent curing system is dicyandiamide. In another preferred embodiment, the latent curing system is dicyandiamide and modified dicyandiamide. In yet another preferred embodiment, the latent curing system is urea derivatives.

[0038] In the present invention, the fiber includes at least one of E-glass fiber, high-strength glass fiber, and quartz fiber. In a preferred embodiment, the fiber is high-strength glass fiber. In another preferred embodiment, the fiber is E-glass fiber. In a preferred embodiment, the fiber is quartz fiber.

[0039] It has been found through research in the present invention that diisocyanate compounds containing groups such as naphthalene ring, biphenyl, or p-phenylene, and bisphenol A polyether can synergistically improve the heat resistance of epoxy resin prepreg, and at the same time can synergistically improve the dielectric properties of epoxy resin prepreg.

[0040] High temperature resistant and low dielectric epoxy resin prepreg

[0041] In one aspect of the present invention, there is provided a high-temperature resistant and low-dielectric epoxy resin prepreg obtained by the preparation method described in the present invention.

[0042] In the present invention, the high-temperature resistant and low-dielectric epoxy resin prepreg is prepared from the following raw materials: 0.05 - 1 part by weight of a first catalyst, 1 - 200 parts by weight of an epoxy resin, 1 - 200 parts by weight of a diisocyanate compound, 0.05 - 1 part by weight of a second catalyst, 1 - 20 parts by weight of bisphenol A polyether, 1 - 100 parts by weight of a liquid epoxy resin, and 1 - 20 parts by weight of a latent curing system.

[0043] In a preferred embodiment, the high-temperature resistant and low-dielectric epoxy resin prepreg is prepared from the following raw materials: 0.1 - 1 part by weight of a first catalyst, 1 - 100 parts by weight of an epoxy resin, 1 - 100 parts by weight of a diisocyanate compound, 0.1 - 1 part by weight of a second catalyst, 5 - 15 parts by weight of bisphenol A polyether, 20 - 50 parts by weight of a liquid epoxy resin, and 6 - 12 parts by weight of a latent curing system.

[0044] In a preferred embodiment, the high-temperature resistant and low-dielectric epoxy resin prepreg is prepared from the following raw materials: 1 - 100 parts by weight of an epoxy resin, 1 - 100 parts by weight of a diisocyanate compound, 5 - 15 parts by weight of bisphenol A polyether, 20 - 50 parts by weight of a liquid epoxy resin, and 6 - 12 parts by weight of a latent curing system.

[0045] In the present invention, the determination of the glass transition temperature, interlaminar shear strength, dielectric constant, and dielectric loss of the high-temperature resistant and low-dielectric epoxy resin prepreg can be carried out using methods and apparatuses known in the art, and no particular limitation is imposed thereon.

[0046] In a preferred embodiment, the high-temperature resistant and low-dielectric epoxy resin prepreg in the present invention has a glass transition temperature of 173 - 180 °C.

[0047] In a preferred embodiment, the high-temperature resistant and low-dielectric epoxy resin prepreg in the present invention has an interlaminar shear strength of 60 - 70 MPa (at 25 °C).

[0048] In a preferred embodiment, the high-temperature resistant and low-dielectric epoxy resin prepreg in the present invention has an interlaminar shear strength of 53 - 63 MPa (at 100 °C).

[0049] In a preferred embodiment, the high-temperature resistant and low-dielectric epoxy resin prepreg in the present invention has a dielectric constant of 3.5 - 4.3.

[0050] In a preferred embodiment, the high-temperature resistant and low-dielectric epoxy resin prepreg in the present invention has a dielectric loss of 0.009 - 0.011.

[0051] Application

[0052] In one aspect of the present invention, there is provided the use of the high-temperature resistant and low-dielectric epoxy resin prepreg of the present invention in high-frequency communication devices. Among them, examples of the high-frequency communication devices include but are not limited to satellite antennas, radar devices, spaceborne communication devices, solar panels, flight control devices, navigation devices, filters, etc.

[0053] Example 1

[0054] The following shows the preparation process and performance determination of the high-temperature resistant and low-dielectric epoxy resin prepreg.

[0055] Bisphenol A glycidyl ether type epoxy resin and 1,5-naphthalene diisocyanate were placed in a reaction kettle at 120 °C in a molar ratio of 6:1 and reacted for 4 h under the action of an imidazole catalyst, and then bisphenol A-terminated poly(phenylene oxide) was added and the reaction was continued for 3 h under the action of a triphenylphosphine catalyst to prepare a high-temperature resistant and low-dielectric epoxy resin. Among them, relative to 100 parts by weight of the sum of the masses of bisphenol A glycidyl ether type epoxy resin and 1,5-naphthalene diisocyanate, the amount of the imidazole catalyst used was 1 part by weight, the amount of bisphenol A-terminated poly(phenylene oxide) used was 15 parts by weight, and the amount of the triphenylphosphine catalyst used was 1 part by weight.

[0056] To 100 parts by weight of the high-temperature resistant and low-dielectric epoxy resin obtained in the above step, add 50 parts by weight of bisphenol A glycidyl ether type epoxy resin and 12 parts by weight of dicyandiamide curing system and mix evenly to prepare a resin system for prepreg with excellent processability. Coating the resin system with a film coater, and then compounding it with high-strength glass fiber via a laminator to prepare a high-temperature resistant and low-dielectric epoxy resin prepreg. The glass transition temperature (DMA), interlaminar shear strength and dielectric properties of the composite material are tested respectively, and the results are shown in Table 1.

[0057] Example 2

[0058] The following shows the preparation process and performance determination of the high-temperature resistant and low-dielectric epoxy resin prepreg.

[0059] Put bisphenol F glycidyl ether type epoxy resin and bisphenol AD glycidyl ether type epoxy resin and 1,5-naphthalene diisocyanate and dimethylbiphenyl diisocyanate in a reaction kettle at 140 °C in a molar ratio of 4.5:1, react for 3 h under the action of an imidazole derivative catalyst, then add bisphenol-terminated polyphenylene oxide, and continue to react for 2 h under the action of triphenylphosphine and tetramethylammonium hydroxide catalysts to prepare a high-temperature resistant and low-dielectric epoxy resin. Among them, relative to 100 parts by weight of the total mass of bisphenol F glycidyl ether type epoxy resin, bisphenol AD glycidyl ether type epoxy resin, 1,5-naphthalene diisocyanate and dimethylbiphenyl diisocyanate, the dosage of the imidazole derivative catalyst is 0.55 parts by weight, the dosage of bisphenol-terminated polyphenylene oxide is 10 parts by weight, and the dosage of triphenylphosphine and tetramethylammonium hydroxide catalysts is 0.55 parts by weight.

[0060] To 100 parts by weight of the high-temperature resistant and low-dielectric epoxy resin obtained in the above step, add 35 parts by weight of bisphenol A glycidyl ether type epoxy resin and bisphenol F glycidyl ether type epoxy resin, and 9 parts by weight of dicyandiamide and modified dicyandiamide curing system and mix evenly to prepare a resin system for prepreg with excellent processability. Coating the resin system with a film coater, and then compounding it with alkali-free glass fiber via a laminator to prepare a high-temperature resistant and low-dielectric epoxy resin prepreg. The glass transition temperature (DMA), interlaminar shear strength and dielectric properties of the composite material are tested respectively, and the results are shown in Table 1.

[0061] Example 3

[0062] The following shows the preparation process and performance determination of the high-temperature resistant and low-dielectric epoxy resin prepreg.

[0063] The liquid phenolic epoxy resin and p-phenylene diisocyanate were placed in a reaction kettle at 160 °C in a molar ratio of 3:1 and reacted for 2 h under the action of a Lewis acid catalyst. Then, bisphenol-terminated polyphenylene oxide was added and the reaction continued for 1 h under the action of a tetramethylammonium hydroxide catalyst to prepare a high-temperature resistant and low-dielectric epoxy resin. Among them, relative to 100 parts by weight of the total mass of the liquid phenolic epoxy resin and p-phenylene diisocyanate, the dosage of the Lewis acid catalyst was 0.1 part by weight, the dosage of bisphenol-terminated polyphenylene oxide was 5 parts by weight, and the dosage of the tetramethylammonium hydroxide catalyst was 0.1 part by weight.

[0064] To 100 parts by weight of the high-temperature resistant and low-dielectric epoxy resin obtained in the above step, 20 parts by weight of the liquid phenolic epoxy resin and 6 parts by weight of the urea derivative curing system were added and mixed evenly to prepare a resin system for prepreg with excellent processability. The resin system was coated with a film by a film coater, and then compounded with quartz fiber by a compounding machine to prepare a high-temperature resistant and low-dielectric epoxy resin prepreg. The glass transition temperature (DMA), interlaminar shear strength and dielectric properties of the composite material were tested respectively, and the results are shown in Table 1.

[0065] Comparative Example 1

[0066] The following shows the preparation process and performance determination of the modified epoxy resin-based prepreg.

[0067] The bisphenol A glycidyl ether type epoxy resin and 1,5-naphthalene diisocyanate were placed in a reaction kettle at 120 °C in a molar ratio of 6:1 and reacted for 4 h under the action of an imidazole catalyst to prepare a modified epoxy resin. Among them, relative to 100 parts by weight of the total mass of the bisphenol A glycidyl ether type epoxy resin and 1,5-naphthalene diisocyanate, the dosage of the imidazole catalyst was 1 part by weight.

[0068] To 100 parts by weight of the modified epoxy resin obtained in the above step, 50 parts by weight of the bisphenol A glycidyl ether type epoxy resin and 12 parts by weight of the dicyandiamide curing system were added and mixed evenly to prepare a resin system for prepreg with excellent processability. The resin system was coated with a film by a film coater, and then compounded with high-strength glass fiber by a compounding machine to prepare a modified epoxy resin-based prepreg. The glass transition temperature (DMA), interlaminar shear strength and dielectric properties of the composite material were tested respectively, and the results are shown in Table 1.

[0069] Comparative Example 2

[0070] The following shows the preparation process and performance determination of the modified epoxy resin-based prepreg.

[0071] The bisphenol A glycidyl ether type epoxy resin and the bis - terminal hydroxy polyphenylene ether are placed in a reaction kettle at 120 °C and reacted for 3 h under the action of a triphenylphosphine catalyst to prepare a modified epoxy resin. Among them, relative to 100 parts by weight of the bisphenol A glycidyl ether type epoxy resin, the dosage of the bis - terminal hydroxy polyphenylene ether is 15 parts by weight, and the dosage of the triphenylphosphine catalyst is 1 part by weight.

[0072] To 100 parts by weight of the modified epoxy resin obtained in the above step, 50 parts by weight of the bisphenol A glycidyl ether type epoxy resin and 12 parts by weight of a dicyandiamide curing system are added and mixed evenly to prepare a resin system for prepreg with excellent processability. The resin system is coated with a film by a film coater, and then compounded with high - strength glass fiber by a compounding machine to prepare a modified epoxy resin - based prepreg. The glass transition temperature (DMA), interlaminar shear strength and dielectric properties of the composite material are tested respectively, and the results are shown in Table 1.

[0073] Comparative Example 3

[0074] The following shows the preparation process and performance determination of the modified epoxy resin - based prepreg.

[0075] The bisphenol A glycidyl ether type epoxy resin and the liquefied diphenylmethane diisocyanate are placed in a reaction kettle at 120 °C in a molar ratio of 6:1 and reacted for 4 h under the action of an imidazole catalyst, then the bis - terminal hydroxy polyphenylene ether is added, and the reaction continues for 3 h under the action of a triphenylphosphine catalyst to prepare a high - temperature resistant and low - dielectric epoxy resin. Among them, relative to 100 parts by weight of the sum of the mass of the bisphenol A glycidyl ether type epoxy resin and the liquefied diphenylmethane diisocyanate, the dosage of the imidazole catalyst is 1 part by weight, the dosage of the bis - terminal hydroxy polyphenylene ether is 15 parts by weight, and the dosage of the triphenylphosphine catalyst is 1 part by weight.

[0076] To 100 parts by weight of the modified epoxy resin obtained in the above step, 50 parts by weight of the bisphenol A glycidyl ether type epoxy resin and 12 parts by weight of a dicyandiamide curing system are added and mixed evenly to prepare a resin system for prepreg with excellent processability. The resin system is coated with a film by a film coater, and then compounded with high - strength glass fiber by a compounding machine to prepare a modified epoxy resin - based prepreg. The glass transition temperature (DMA), interlaminar shear strength and dielectric properties of the composite material are tested respectively, and the results are shown in Table 1.

[0077] Compared with the comparative examples, the glass transition temperature of the high-temperature resistant and low-dielectric epoxy resin composite prepared in the example is >170 °C, the interlaminar shear strength retention rate of the composite at 100 °C is >80%, it can be used for a long time in an environment of 100 °C, the dielectric constant is ≤4.3, and the dielectric loss is ≤0.011, having excellent high-temperature resistance and dielectric properties. In Comparative Example 1, for the composite prepared by modifying epoxy resin with 1,5-naphthalene diisocyanate, although the glass transition temperature reaches 165 °C, the dielectric constant reaches 4.7, and it is difficult to meet the technical requirements of the low-dielectric properties of the composite; in Comparative Example 2, for the composite prepared by modifying epoxy resin with bisphenol A polyether, the dielectric constant reaches 4.5, but the glass transition temperature is only 159 °C, and it is difficult to meet the technical requirements of high-temperature resistance and low dielectric of the composite; in Comparative Example 3, for the composite prepared by modifying epoxy resin with liquefied diphenylmethane diisocyanate and bisphenol A polyether, the glass transition temperature reaches 168 °C, the dielectric constant reaches 4.4, and the improvement of heat resistance and dielectric properties is still not as good as that of the composite prepared in Example 1. The present invention finally solves the technical problem that it is difficult for traditional epoxy prepregs to balance high-temperature resistance and low dielectric, and broadens the application of epoxy prepregs in the composite material field such as high-frequency communication equipment.

[0078] Table 1 Performance of composites in different examples and comparative examples

[0079]

[0080]

[0081] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing examples, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing examples, or perform equivalent replacements on some of the technical features. And these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various examples of the present invention.

Claims

1. A preparation method of a high-temperature resistant and low-dielectric epoxy resin prepreg, characterized in that, It includes the following steps: (1) In the presence of a first catalyst, an epoxy resin is reacted with an aromatic group-containing diisocyanate compound at 120 - 160 °C for 2 - 4 h. Then, a bisphenol-terminated polyphenylene ether is added, and the reaction is continued for 1 - 3 h in the presence of a second catalyst to obtain a high-temperature resistant and low-dielectric epoxy resin. Among them, the molar ratio of the epoxy resin to the diisocyanate compound is (3 - 6):1; (2) The high-temperature resistant and low-dielectric epoxy resin is mixed with a liquid epoxy resin and a latent curing system to obtain a resin system for prepreg. Among them, the high-temperature resistant and low-dielectric epoxy resin is 100 parts by weight, the liquid epoxy resin is 20 - 50 parts by weight, and the latent curing system is 6 - 12 parts by weight; (3) The resin system for prepreg is prepared into a film, which is then laminated with fibers to obtain the high-temperature resistant and low-dielectric epoxy resin prepreg.

2. The preparation method according to claim 1, characterized in that, In step (1), the dosage of the first catalyst is 0.1 - 1% of the sum of the masses of the epoxy resin and the diisocyanate compound, the dosage of the second catalyst is 0.1 - 1% of the sum of the masses of the epoxy resin and the diisocyanate compound, and the dosage of the bisphenol-terminated polyphenylene ether is 5 - 15% of the sum of the masses of the epoxy resin and the diisocyanate compound.

3. The preparation method according to claim 1, characterized in that, The first catalyst includes at least one of imidazole, imidazole derivatives, Lewis acids, and base complexes.

4. The preparation method according to claim 1, characterized in that The epoxy resin includes at least one of bisphenol A glycidyl ether, bisphenol F glycidyl ether, bisphenol AD glycidyl ether, liquid phenolic epoxy resin, and alicyclic epoxy resin.

5. The preparation method according to claim 1, wherein The aromatic group-containing diisocyanate compound includes at least one of 1,5-naphthalene diisocyanate, dimethylbiphenyl diisocyanate, and p-phenylene diisocyanate.

6. The preparation method according to claim 1, characterized in that, The second catalyst includes at least one of triphenylphosphine and tetramethylammonium hydroxide.

7. The preparation method according to claim 1, characterized in that, The latent curing system includes at least one of dicyandiamide, modified dicyandiamide, and urea derivatives.

8. The preparation method according to claim 1, characterized in that, The fibers include at least one of E-glass fiber, high-strength glass fiber, and quartz fiber.

9. A high-temperature resistant and low-dielectric epoxy resin prepreg, characterized in that, It is obtained by the preparation method described in any one of claims 1 - 8.

10. Application of the high-temperature resistant and low-dielectric epoxy resin prepreg according to claim 9 in high-frequency communication devices.

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