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

Abstract

The application discloses a high-temperature-resistant low-dielectric epoxy resin prepreg as well as a preparation method and application thereof. Research finds that by introducing a suitable group, the resin matrix can be endowed with good high-temperature resistance, and the glass transition temperature of the epoxy resin system can be improved. Moreover, by introducing a group with regularity and symmetry into a molecular main chain through molecular structure design, the polarity and dipole moment of a molecular chain can be reduced, so that the dielectric property of the material is improved. In addition, by reasonably controlling the raw material ratio and a modification process route, the high-temperature-resistant low-dielectric epoxy resin has a chemical tackifying effect, the viscosity of the prepreg resin system can be improved, and the flowability and permeability of the resin matrix of the prepreg in a molding process are ensured.

Description

TECHNICAL FIELD

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

[0002] With the rapid development of high-tech fields such as high-frequency communication, the demand for high-temperature-resistant low-dielectric epoxy resin-based composite materials is increasing. In some special application scenarios, traditional epoxy prepregs have defects of poor high-temperature resistance and insufficient dielectric properties, which can lead to softening and decomposition at high temperatures, resulting in performance degradation, signal delay and energy loss, and thus cannot meet the stringent requirements of high-tech industries on materials. Therefore, developing epoxy resin-based prepregs with both high-temperature resistance and low dielectric properties has become a research hotspot.

[0003] Chinese patent application CN104726045A uses a base epoxy resin containing heat-resistant groups such as aromatic rings, alicyclic rings and heterocyclic rings in the molecular chain, and the product has a temperature resistance of 250 DEG C. However, the epoxy resin prepared by the method has a high dielectric property due to the addition of aluminum oxide fillers. In addition, Chinese patent application CN119217811A introduces cage-type polyhedral oligomeric silsesquioxane resin (POSS), and uses specific proportions of dicyclopentadiene phenol modified epoxy resin and inorganic fillers such as silicon powder to synergistically improve the dielectric properties and heat resistance of the material. However, the addition of a large amount of fillers makes it difficult to disperse uniformly, resulting in poor film-forming properties of the resin system, which is difficult to meet the process characteristics during the preparation of the prepreg.

[0004] Therefore, there is an urgent need to develop an epoxy resin-based prepreg with high-temperature resistance, low dielectric property and process characteristics suitable for the preparation of the prepreg. SUMMARY

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

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

[0007] (1) reacting an epoxy resin with a diisocyanate compound containing an aromatic group in the presence of a first catalyst at 120-160 DEG C for 2-4 h, adding a double-end hydroxyl polyphenyl ether, and continuing to react in the presence of a second catalyst for 1-3 h 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;

[0008] (2) mixing the high-temperature-resistant 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 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) preparing a film from the resin system for prepreg, and compounding the film with fibers to obtain the high-temperature-resistant low-dielectric epoxy resin prepreg.

[0010] In some embodiments, the preparation method according to the present application, wherein in step (1), the amount of the first catalyst is 0.1-1% of the sum of the mass of the epoxy resin and the diisocyanate compound, the amount of the second catalyst is 0.1-1% of the sum of the mass of the epoxy resin and the diisocyanate compound, and the amount of the double-end hydroxyl polyphenyl ether is 5-15% of the sum of the mass of the epoxy resin and the diisocyanate compound.

[0011] In some embodiments, the preparation method according to the present application, wherein the first catalyst comprises at least one of imidazole, imidazole derivative, Lewis acid and base complex.

[0012] In some embodiments, the preparation method according to the present application, wherein the epoxy resin comprises 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 some embodiments, the preparation method according to the present application, wherein the diisocyanate compound containing aromatic groups comprises at least one of 1,5-naphthalene diisocyanate, dimethyl diphenyl diisocyanate and p-phenylene diisocyanate.

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

[0015] In some embodiments, the preparation method according to the present application, wherein the latent curing system comprises at least one of dicyandiamide, modified dicyandiamide and urea derivative.

[0016] In some embodiments, the preparation method according to the present application, wherein the fibers comprise at least one of non-alkali glass fiber, high-strength glass fiber and quartz fiber.

[0017] The second aspect of the present application provides a high-temperature-resistant low-dielectric epoxy resin prepreg obtained by the preparation method of the first aspect of the present application.

[0018] In a third aspect, the application provides use of the high-temperature-resistant and low-dielectric epoxy resin prepreg according to the second aspect of the application in high-frequency communication equipment.

[0019] The application has found that diisocyanate containing naphthalene ring, biphenyl or p-benzene group can endow the resin matrix with good high-temperature resistance, and polyphenyl ether can synergistically improve the glass transition temperature of the epoxy resin system. Moreover, by introducing naphthalene ring, biphenyl or p-benzene group with regularity and symmetry into the main chain of the molecule through molecular structure design, the polarity and dipole moment of the molecular chain can be reduced, the dielectric property of the material can be improved, and the effect of synergistically improving the dielectric property of the epoxy resin with polyphenyl ether can be achieved.

[0020] In addition, by reasonably controlling the raw material ratio and modification process route, using diisocyanate containing aromatic groups as the linear chain extender of the epoxy resin, the distance between the rigid crosslinking points in the crosslinking network of the cured product can be increased, the toughness of the resin system can be endowed, and the initial viscosity of the resin matrix can be improved. Further, by introducing polyphenyl ether segments, the flexibility of the resin matrix and the viscosity of the resin system can be improved. Therefore, the high-temperature-resistant and low-dielectric epoxy resin of the application has a chemical tackifying effect, can improve the viscosity of the prepreg resin system, and can ensure the flowability and permeability of the resin matrix of the prepreg in the molding process. DETAILED DESCRIPTION

[0021] Various exemplary embodiments of the application will now be described in detail with reference to the drawings. The detailed description is not to be considered to limit the application in any way, but rather to explain certain aspects, features and embodiments of the application.

[0022] It should be understood that the terms used in the present application merely describe specific embodiments, and are not intended to limit the application. In addition, for the numerical range in the present application, it is understood that the upper limit and the lower limit of the range and every intermediate value between them are specifically disclosed. Each smaller range between any stated value or stated range and any other stated value or intermediate value within the stated range is also included in the present application. The upper limit and the lower limit of these smaller ranges can be independently included or excluded from the range.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application, preferred methods and materials are described. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials in connection with which the documents are cited. In the case of conflict between the content of this specification and that of any document incorporated by reference, the content of this specification prevails.

[0024] Preparation method

[0025] In one aspect of the present application, a method for preparing a high-temperature resistant low-dielectric epoxy resin prepreg is provided.

[0026] In one preferred embodiment, the method for preparing the present application comprises the following steps:

[0027] (1) reacting an epoxy resin with a diisocyanate compound containing aromatic group in the presence of a first catalyst at 120-160°C (e.g. 120, 125, 130, 135, 140, 145, 150, 155, 160°C) for 2-4h (e.g. 2, 2.2, 2.4, 2.6, 2.8, 3, 3.2, 3.4, 3.6, 3.8, 4h), adding a dihydroxyl-terminated polyphenyl ether, and continuing to react in the presence of a second catalyst for 1-3h (e.g. 1, 1.2, 1.4, 1.6, 1.8, 2, 2.2, 2.4, 2.6, 2.8, 3h) 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 resin system for prepreg, 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) preparing a film from the resin system for prepreg, and compounding the film with fibers to obtain the high-temperature resistant low-dielectric epoxy resin prepreg.

[0030] To improve the high temperature resistance and dielectric properties of the high temperature resistant 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 amount of the catalyst should be controlled within a suitable range. In the present application, the molar ratio of the epoxy resin to the diisocyanate compound is (3-6): 1, for example 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 amount of the first catalyst is 0.1-1% of the sum of the mass of the epoxy resin and the diisocyanate compound, for example 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 amount of the first catalyst is 1% of the sum of the mass 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 amount of the first catalyst is 0.55% of the sum of the mass 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 amount of the first catalyst is 0.1% of the sum of the mass of the epoxy resin and the diisocyanate compound.

[0031] To improve the high temperature resistance and dielectric properties of the high temperature resistant low dielectric epoxy resin prepreg, the amount of the double-end hydroxyl polyphenyl ether should not be too high or too low, and the amount of the catalyst should be controlled within a suitable range. If the amount of the polyphenyl ether is too large, the curing performance of the epoxy resin will tend to deteriorate, and if the amount of the polyphenyl ether is too small, the dielectric properties of the prepreg will tend to deteriorate. In a preferred embodiment, the amount of the double-end hydroxyl polyphenyl ether is 5-15% of the sum of the mass of the epoxy resin and the diisocyanate compound, for example 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, or any value within the above range, and the amount of the second catalyst is 1% of the sum of the mass of the epoxy resin and the diisocyanate compound, for example 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 one preferred embodiment, the amount of the dihydroxyl-terminated polyphenylene ether is 15% of the sum of the mass of the epoxy resin and the diisocyanate compound, and the amount of the second catalyst is 1% of the sum of the mass of the epoxy resin and the diisocyanate compound. In another preferred embodiment, the amount of the dihydroxyl-terminated polyphenylene ether is 10% of the sum of the mass of the epoxy resin and the diisocyanate compound, and the amount of the second catalyst is 0.55% of the sum of the mass of the epoxy resin and the diisocyanate compound. In yet another preferred embodiment, the amount of the dihydroxyl-terminated polyphenylene ether is 5% of the sum of the mass of the epoxy resin and the diisocyanate compound, and the amount of the second catalyst is 0.1% of the sum of the mass of the epoxy resin and the diisocyanate compound.

[0033] In the present application, the first catalyst includes at least one of imidazole, imidazole derivative, Lewis acid, and base complex. In one preferred embodiment, the first catalyst is imidazole. In another preferred embodiment, the first catalyst is imidazole derivative. In yet another preferred embodiment, the first catalyst is Lewis acid.

[0034] In the present application, the epoxy resin includes at least one of bisphenol A glycidyl ether, bisphenol F glycidyl ether, bisphenol AD glycidyl ether, liquid phenol novolac epoxy resin, and alicyclic epoxy resin. In one 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 phenol novolac epoxy resin.

[0035] In the present application, the diisocyanate compound including an aromatic group includes at least one of 1,5-naphthalene diisocyanate, dimethyl diphenyl diisocyanate, and p-phenylene diisocyanate. In one preferred embodiment, the diisocyanate compound is 1,5-naphthalene diisocyanate. In another preferred embodiment, the diisocyanate compound is 1,5-naphthalene diisocyanate and dimethyl diphenyl diisocyanate. In yet another preferred embodiment, the diisocyanate compound is p-phenylene diisocyanate.

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

[0037] In the present invention, the latent curing system comprises 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 comprises at least one of alkali-free 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 alkali-free glass fiber. In a preferred embodiment, the fiber is quartz fiber.

[0039] The present invention has found that diisocyanate compounds containing naphthalene ring, biphenyl or p-benzene group and double-end hydroxyl polyphenyl ether can synergistically improve the temperature resistance of epoxy resin prepreg, and can also synergistically improve the dielectric properties of epoxy resin prepreg.

[0040] High temperature resistant low dielectric epoxy resin prepreg

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

[0042] In the present invention, the high-temperature-resistant low-dielectric epoxy resin prepreg is prepared from raw materials comprising 0.05-1 parts 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 parts by weight of a second catalyst, 1-20 parts by weight of a double-end hydroxyl polyphenyl ether, 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 low-dielectric epoxy resin prepreg is prepared from raw materials comprising 0.1-1 parts 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 parts by weight of a second catalyst, 5-15 parts by weight of a double-end hydroxyl polyphenyl ether, 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 low-dielectric epoxy resin prepreg is prepared from raw materials comprising 1-100 parts by weight of an epoxy resin, 1-100 parts by weight of a diisocyanate compound, 5-15 parts by weight of a double-end hydroxyl polyphenyl ether, 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 application, the determination of the glass transition temperature, interlaminar shear strength, dielectric constant and dielectric loss of the high-temperature-resistant low-dielectric epoxy resin prepreg can be carried out by using methods and devices known in the art, and no particular limitation is made thereto.

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

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

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

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

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

[0051] Applications

[0052] In one aspect of the present application, the use of the high-temperature-resistant low-dielectric epoxy resin prepreg described in the present application in high-frequency communication equipment is provided. Examples of the high-frequency communication equipment include, but are not limited to, satellite antennas, radar equipment, satellite-borne communication equipment, solar panels, flight control equipment, navigation equipment, filters, etc.

[0053] Example 1

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

[0055] The bisphenol A glycidyl ether type epoxy resin and 1,5-naphthalene diisocyanate were placed in a 120℃ reaction kettle in a molar ratio of 6:1, and reacted for 4h under the action of imidazole catalyst, then bis-hydroxyl polyphenyl ether was added, and the reaction was continued for 3h under the action of triphenylphosphine catalyst to prepare a high-temperature-resistant 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 1,5-naphthalene diisocyanate, the amount of imidazole catalyst is 1 part by weight, the amount of bis-hydroxyl polyphenyl ether is 15 parts by weight, and the amount of triphenylphosphine catalyst is 1 part by weight.

[0056] To 100 parts by weight of the high-temperature-resistant low-dielectric epoxy resin obtained in the above step, 50 parts by weight of a bisphenol A glycidyl ether type epoxy resin and 12 parts by weight of a dicyandiamide curing system were added and mixed uniformly to prepare a resin system for prepreg with excellent processability. The resin system was coated by using a film applicator, and then was compounded with high-strength glass fibers by using a compounding machine to prepare a high-temperature-resistant 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.

[0057] Example 2

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

[0059] The bisphenol F glycidyl ether type epoxy resin and the bisphenol AD glycidyl ether type epoxy resin were placed in a 140°C reaction kettle in a molar ratio of 4.5:1 with 1,5-naphthalene diisocyanate and dimethyl diphenyl diisocyanate, and reacted for 3h under the action of an imidazole derivative catalyst, and then a double-end hydroxyl polyphenyl ether was added and continued to react for 2h under the action of a triphenylphosphine and tetramethylammonium hydroxide catalyst to prepare a high-temperature-resistant low-dielectric epoxy resin. Among them, relative to 100 parts by weight of the sum of the bisphenol F glycidyl ether type epoxy resin and the bisphenol AD glycidyl ether type epoxy resin and the 1,5-naphthalene diisocyanate and dimethyl diphenyl diisocyanate, the amount of the imidazole derivative catalyst was 0.55 parts by weight, the amount of the double-end hydroxyl polyphenyl ether was 10 parts by weight, and the amount of the triphenylphosphine and tetramethylammonium hydroxide catalyst was 0.55 parts by weight.

[0060] To 100 parts by weight of the high-temperature-resistant low-dielectric epoxy resin obtained in the above step, 50 parts by weight of a bisphenol A glycidyl ether type epoxy resin and 12 parts by weight of a dicyandiamide curing system were added and mixed uniformly to prepare a resin system for prepreg with excellent processability. The resin system was coated by using a film applicator, and then was compounded with high-strength glass fibers by using a compounding machine to prepare a high-temperature-resistant 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.

[0061] Example 3

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

[0063] The liquid phenolic epoxy resin and p-phenylene diisocyanate are placed in a 160°C reaction kettle in a molar ratio of 3:1, and reacted for 2h under the action of a Lewis acid catalyst, then the dihydroxyl-terminated polyphenyl ether is added, and the reaction is continued for 1h under the action of a tetramethylammonium hydroxide catalyst, to prepare a high-temperature-resistant low-dielectric epoxy resin. In 100 parts by weight of the sum of the liquid phenolic epoxy resin and p-phenylene diisocyanate, the amount of the Lewis acid catalyst is 0.1 parts by weight, the amount of the dihydroxyl-terminated polyphenyl ether is 5 parts by weight, and the amount of the tetramethylammonium hydroxide catalyst is 0.1 parts by weight.

[0064] To 100 parts by weight of the high-temperature-resistant low-dielectric epoxy resin obtained in the above step, 20 parts by weight of liquid phenolic epoxy resin and 6 parts by weight of a urea derivative curing system are added and uniformly mixed to prepare a resin system for prepreg with excellent processability. The resin system is coated by a film coating machine, and then compounded with quartz fiber by a compound machine to prepare a high-temperature-resistant 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.

[0065] Comparative Example 1

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

[0067] The bisphenol A glycidyl ether type epoxy resin and 1,5-naphthalene diisocyanate are placed in a 120°C reaction kettle in a molar ratio of 6:1, and reacted for 4h under the action of an imidazole catalyst to prepare a modified epoxy resin. In 100 parts by weight of the sum of the bisphenol A glycidyl ether type epoxy resin and 1,5-naphthalene diisocyanate, the amount of the imidazole catalyst is 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 bisphenol A glycidyl ether type epoxy resin and 12 parts by weight of a dicyandiamide curing system are added and uniformly mixed to prepare a resin system for prepreg with excellent processability. The resin system is coated by a film coating machine, and then compounded with high-strength glass fiber by a compound 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.

[0069] Comparative Example 2

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

[0071] The modified epoxy resin was prepared by reacting bisphenol A glycidyl ether type epoxy resin and double-end hydroxyl polyphenyl ether in a 120°C reaction kettle for 3h in the presence of triphenylphosphine catalyst. In this case, the amount of double-end hydroxyl polyphenyl ether was 15 parts by weight and the amount of triphenylphosphine catalyst was 1 part by weight, relative to 100 parts by weight of bisphenol A glycidyl ether type epoxy resin.

[0072] The resin system for prepreg with excellent processability was prepared by adding 50 parts by weight of bisphenol A glycidyl ether type epoxy resin and 12 parts by weight of dicyandiamide curing system to 100 parts by weight of the modified epoxy resin obtained in the above step and mixing uniformly. The resin system was coated by using a film applicator and then was compounded with high-strength glass fiber by using a compounder 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.

[0073] Comparative Example 3

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

[0075] The high-temperature-resistant low-dielectric epoxy resin was prepared by reacting bisphenol A glycidyl ether type epoxy resin and liquefied diphenyl methane diisocyanate in a 120°C reaction kettle for 4h in the presence of imidazole catalyst, and then adding double-end hydroxyl polyphenyl ether and continuing to react for 3h in the presence of triphenylphosphine catalyst. In this case, the amount of imidazole catalyst was 1 part by weight, the amount of double-end hydroxyl polyphenyl ether was 15 parts by weight, and the amount of triphenylphosphine catalyst was 1 part by weight, relative to 100 parts by weight of the sum of the mass of bisphenol A glycidyl ether type epoxy resin and liquefied diphenyl methane diisocyanate.

[0076] The resin system for prepreg with excellent processability was prepared by adding 50 parts by weight of bisphenol A glycidyl ether type epoxy resin and 12 parts by weight of dicyandiamide curing system to 100 parts by weight of the modified epoxy resin obtained in the above step and mixing uniformly. The resin system was coated by using a film applicator and then was compounded with high-strength glass fiber by using a compounder 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.

[0077] Compared with the comparative examples, the high-temperature-resistant low-dielectric epoxy resin composite prepared in the examples has a glass transition temperature of > 170℃, a 100℃ interlaminar shear strength retention rate of > 80%, can be used for a long time in an environment of 100℃, a dielectric constant of ≤ 4.3, and a dielectric loss of ≤ 0.011, and has excellent high-temperature resistance and dielectric properties. In Comparative Example 1, the composite prepared by modifying the epoxy resin with 1,5-naphthalene diisocyanate has a glass transition temperature of 165℃, but a dielectric constant of 4.7, which is difficult to meet the technical requirements of low dielectric properties of the composite; in Comparative Example 2, the composite prepared by modifying the epoxy resin with double-end hydroxyl polyphenyl ether has a dielectric constant of 4.5, but a glass transition temperature of only 159℃, which is difficult to meet the technical requirements of high-temperature resistance and low dielectric properties of the composite; in Comparative Example 3, the composite prepared by modifying the epoxy resin with liquefied diphenyl methane diisocyanate and double-end hydroxyl polyphenyl ether has a glass transition temperature of 168℃ and a dielectric constant of 4.4, and the heat resistance and dielectric properties are still not as good as those of the composite prepared in Example 1. The present application finally solves the technical problem that the traditional epoxy prepreg is difficult to have both high-temperature resistance and low dielectric properties, and widens the application of the epoxy prepreg in the field of composite materials for high-frequency communication equipment and the like.

[0078] Table 1 Properties of the composite materials of 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 application, and not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing examples, or make equivalent replacements for part of the technical features. Such 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 embodiments of the present application.

Claims

1. A method for preparing a high-temperature resistant, low-dielectric epoxy resin prepreg, characterized in that, Includes the following steps: (1) Under the presence of a first catalyst, epoxy resin is reacted with a diisocyanate compound containing aromatic groups at 120-160°C for 2-4 h, then a hydroxyl-terminated polyphenylene ether is added, and the reaction is continued for 1-3 h under the presence of a second catalyst to obtain a high-temperature resistant, low-dielectric epoxy resin. The first catalyst includes at least one of imidazole, imidazole derivatives, and Lewis acids. The diisocyanate compound containing aromatic groups contains a naphthalene ring, biphenyl, or p-phenylene structure. The diisocyanate compound containing aromatic groups is at least one of 1,5-naphthalene diisocyanate, dimethyl biphenyl diisocyanate, and p-phenylene diisocyanate. The second catalyst includes at least one of triphenylphosphine and tetramethylammonium hydroxide. The molar ratio of epoxy resin to diisocyanate compound is (3-6):

1. The amount of hydroxyl-terminated polyphenylene ether is 5-15% of the sum of the mass of the epoxy resin and the diisocyanate compound. (2) The high-temperature resistant low-dielectric epoxy resin is mixed with liquid epoxy resin and latent curing system to obtain a resin system for prepreg, wherein the high-temperature resistant low-dielectric epoxy resin is 100 parts by weight, the liquid epoxy resin is 20-50 parts by weight, the latent curing system is 6-12 parts by weight, and the epoxy resin is at least one of bisphenol A glycidyl ether, bisphenol F glycidyl ether, bisphenol AD ​​glycidyl ether, liquid phenolic epoxy resin and alicyclic epoxy resin; (3) The prepreg is prepared into a film using a resin system and then compounded with fibers to obtain the high-temperature resistant, low-dielectric epoxy resin prepreg.

2. The preparation method according to claim 1, characterized in that, In step (1), the amount of the first catalyst is 0.1-1% of the sum of the mass of the epoxy resin and the diisocyanate compound, and the amount of the second catalyst is 0.1-1% of the sum of the mass of the epoxy resin and the diisocyanate compound.

3. 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.

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

5. A high-temperature resistant, low-dielectric epoxy resin prepreg, characterized in that, It is obtained by the preparation method described in any one of claims 1-4.

6. The application of the high-temperature resistant, low-dielectric epoxy resin prepreg according to claim 5 in high-frequency communication equipment.

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