Cycloolefin / epoxy resin blends, prepregs, composites and their preparation methods

Abstract

This invention discloses a cyclic olefin / epoxy resin mixture, a prepreg, a composite material, and a preparation method thereof. The cyclic olefin / epoxy resin mixture, based on 100 parts by weight of liquid epoxy resin and solid epoxy resin, comprises the following components: liquid epoxy resin: 0-45 parts by weight; epoxy value of the liquid epoxy resin: 0.41-1.0; solid epoxy resin: 55-100 parts by weight; epoxy value of the solid epoxy resin: 0.12-0.6; cyclic olefin resin: 5-25 parts by weight; the cyclic olefin resin is one or more selected from dicyclopentadiene, dicyclopentadiene polymer, norbornene, and ethylene-imide norbornene; solvent: 40-70 parts by weight. Using the cyclic olefin / epoxy resin mixture of this invention can overcome many defects in the solution impregnation method for preparing prepregs, and the impact strength of the composite material made from the prepared prepreg is improved to a certain extent.

Description

TECHNICAL FIELD

[0001] The present application relates to a mixture of cyclic olefin and epoxy resin, a fiber prepreg, a composite material and a preparation method. BACKGROUND

[0002] Currently commercially available fiber prepregs are mainly epoxy resin matrix prepregs, and the methods for preparing the prepregs mainly include melt impregnation and solution impregnation.

[0003] The prior art mainly uses epoxy resin as the main resin system and adds other additives to prepare the prepreg, and the performance of the fiber prepreg prepared in this way is limited by the resin itself. Although the prior art can improve the performance of the product by adding various additives, the cost of the additives is relatively high, and if the amount of the additives is not properly controlled, the overall quality and performance will be affected, and even the resin cannot be normally cured. For example, the impact performance of the fiber prepreg prepared from the epoxy resin is affected. In order to improve the impact performance of the epoxy resin prepreg, the epoxy resin itself is usually toughened and modified, mainly by adding rubber particles and elastomers for toughening and modification. However, by this way of toughening, if the amount of the additives is too small, the toughening effect is not achieved, and if the amount is too large, the processing property is deteriorated and the product quality is decreased. Moreover, the uniformity of the dispersion cannot be guaranteed. The cost is also a problem.

[0004] Dicyclopentadiene has relatively high catalytic efficiency with catalyst, and can be cured in a few minutes at room temperature. If dicyclopentadiene is added to the epoxy resin system to prepare a prepreg by melt impregnation, the dicyclopentadiene itself will be cured in the high-temperature process, and therefore, melt impregnation is not suitable for adding dicyclopentadiene to the epoxy system to prepare a prepreg.

[0005] Similarly, if dicyclopentadiene is introduced into the epoxy resin system to prepare a prepreg by solution impregnation, appropriate process needs to be adjusted. If any step is not properly handled in the preparation of the prepreg resin solution and the fiber prepreg product, the fiber prepreg cannot be prepared. For example, the patent document CN113736211A uses liquid epoxy to prepare a dicyclopentadiene / epoxy resin composite by solution impregnation. The viscosity of the prepared resin composition is relatively large, and the resin on the surface of the fiber is not uniform, which cannot meet the quality requirements of the finished prepreg.

[0006] The above problems need to be solved. SUMMARY

[0007] The technical problem to be solved by the present application is to overcome the defects of high cost and poor impact performance of the fiber prepreg prepared by the existing melt impregnation method and solution impregnation method, and to provide a cyclic olefin / epoxy resin mixture, a fiber prepreg, a composite material and a preparation method. The cyclic olefin / epoxy resin mixture of the present application can overcome various defects of the solution impregnation method for preparing the prepreg, and the impact strength of the composite material prepared by the prepreg is improved to a certain extent.

[0008] The present application provides the following technical solutions to solve the above technical problems.

[0009] The present application provides a cyclic olefin / epoxy resin mixture, which comprises the following components based on 100 parts by weight of the total liquid epoxy resin and solid epoxy resin:

[0010] Liquid epoxy resin: 0-45 parts by weight; the epoxy value of the liquid epoxy resin is 0.41-1.0;

[0011] Solid epoxy resin: 55-100 parts by weight; the epoxy value of the solid epoxy resin is 0.12-0.6;

[0012] Cyclic olefin resin: 5-25 parts by weight; the cyclic olefin resin is one or more of dicyclopentadiene (DCPD), dicyclopentadiene multimer, norbornene and ethylidene norbornene;

[0013] Curing agent: 1-5 parts by weight;

[0014] Promoter: 1-5 parts by weight;

[0015] Catalyst: 0.0005-0.01 parts by weight;

[0016] Solvent: 40-70 parts by weight.

[0017] In the present application, the viscosity of the cyclic olefin / epoxy resin mixture at 25°C can be 5000-9000 cPs, preferably 6000-9000 cPs, for example 6300 cPs, 6700 cPs, 6900 cPs, 7300 cPs, 7800 cPs, 8000 cPs, 8500 cPs or 8600 cPs.

[0018] In the present application, the epoxy value of the liquid epoxy resin is preferably 0.41-0.85, more preferably 0.48-0.51, 0.56-0.63, 0.7-0.76, 0.83-0.94 or 0.83-1.

[0019] In this invention, the viscosity of the liquid epoxy resin at 25°C can be 200-18000 cPs, for example 200-14000 cPs, 300-450 cPs, 2000-5000 cPs, 3000-6000 cPs, 2000-3500 cPs or 11000-15000 cPs.

[0020] In this invention, the epoxy value of the solid epoxy resin is preferably 0.12-0.53, more preferably 0.2-0.22, 0.21, 0.46-0.53 or 0.44-0.51.

[0021] In this invention, the softening point of the solid epoxy resin at 25°C can be 50-90°C, for example 62°C, 63°C, 66°C, 70°C, 75°C, 76°C, 80°C, 85°C or 87°C.

[0022] In this invention, the cyclic olefin resin is preferably dicyclopentadiene (DCPD).

[0023] In this invention, when the cyclic olefin resin includes a dicyclopentadiene polymer, the dicyclopentadiene polymer may be one or more of tricyclopentadiene (TCPD), tetracyclopentadiene (TeCPD), and pentacyclopentadiene (PCPD). TeCPD is an abbreviation for tetracyclopentadiene as defined in this invention; PCPD is an abbreviation for pentacyclopentadiene as defined in this invention, and neither has any other special meaning.

[0024] In some preferred embodiments of the present invention, the cyclic olefin resin is a mixture of dicyclopentadiene and tricyclopentadiene; wherein the weight ratio of the dicyclopentadiene to the tricyclopentadiene is (5-30):(5-30), for example 10:20, 10:10 or 15:10.

[0025] In this invention, TCPD, TePCD, and PCPD are prepared by the following method:

[0026] (1) 5 kg of dicyclopentadiene was added to the reactor and heated to 200 °C under nitrogen protection and kept for 0.5 h to obtain a liquid mixture of DCPD, TCPD, TeCPD and PCPD.

[0027] (2) Cool the liquid mixture to 120°C and feed it into the first distillation column for negative pressure distillation. The substance obtained at the top of the column is DCPD, and the bottom of the column is a mixture of TCPD, TeCPD and PCPD. The bottom material is then transported to the second distillation column for further negative pressure distillation. The substance obtained at the top of the column is TCPD, and the bottom of the column is a mixture of TeCPD and PCPD.

[0028] (3) The bottom material of the tower is subjected to negative pressure distillation, and the resulting fraction is TeCPD. The residue contains PCPD.

[0029] (4) Wash the residue with toluene and collect the washing liquid. Remove the toluene solvent by vacuum distillation to obtain PCPD.

[0030] In this invention, the liquid epoxy resin, or the solid epoxy resin, may be a conventional resin in the art, such as one or more of glycidyl ether type epoxy resin, glycidyl amine type epoxy resin, glycidyl ester epoxy resin, and alicyclic epoxy resin.

[0031] The glycidyl ether type epoxy resin may be one or more of bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol AD ​​type epoxy resin and phenolic epoxy resin, such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol AD ​​type epoxy resin or phenolic epoxy resin.

[0032] The glycidylamine type epoxy resin may be one or more of 4,4-diaminodiphenylmethane tetraglycidylamine, diglycidyl-p-aminophenol, triglycidyl-p-aminophenol, and tetraglycidyl-diaminodiphenylmethane.

[0033] The glycidyl ester epoxy resin may be one or more of the following: 4,5-epoxyhexane-1,2-dicarboxylic acid diglycidyl ester, isophthalic acid diglycidyl ester, tetrahydrophthalic acid diglycidyl ester, and hexahydrophthalic acid diglycidyl ester.

[0034] The alicyclic epoxy resin may be one or more of 1,2-epoxy-4-vinylcyclohexane, methyl 3,4-epoxycyclohexane carboxylate, bis((3,4-epoxycyclohexyl)methyl)adipic acid ester, 3,4-epoxycyclohexylmethyl methacrylate, and N,N,N,N,-tetracyclooxypropyl-4,4-diaminodiphenylmethane.

[0035] In this invention, the curing agent may be a conventional epoxy resin latent curing agent in the art, such as one or more of aliphatic amines, aromatic amines, dicyandiamides, imidazoles, organic acid anhydrides, organic hydrazides, and Lewis acids.

[0036] In some preferred embodiments of the present invention, the liquid epoxy resin is a mixture of bisphenol A type epoxy resin and 1,2-epoxy-4-vinylcyclohexane; wherein the weight ratio of the bisphenol A type epoxy resin to the 1,2-epoxy-4-vinylcyclohexane is (5-30):(5-30), for example 10:20, 10:10 or 15:10.

[0037] In some preferred embodiments of the present invention, the solid epoxy resin is a mixture of bisphenol A type epoxy resin and phenolic epoxy resin; wherein the weight ratio of bisphenol A type epoxy resin to phenolic epoxy resin is (40-70):(5-30), for example 50:30 or 60:20.

[0038] In this invention, the accelerator may be one or more of the following conventional epoxy resin latent curing accelerators in the art: imidazole compounds and their derivatives and salts, urea derivatives, organic guanidine derivatives, phosphorus-containing compounds, transition metal complexes and composite accelerators, tertiary amines and tertiary amine salts, quaternary phosphine salts, Lewis acid-amine complexes and acetylacetone transition metal complexes.

[0039] In this invention, the catalyst can be a conventional water- and oxygen-resistant catalyst in the art that can cure cyclic olefin resins in an air atmosphere, such as a ruthenium-based catalyst.

[0040] The ruthenium-based catalyst can be a Grubbs-type catalyst or a Hoveyda-Grubbs-type catalyst.

[0041] Preferably, the ruthenium-based catalyst is a second-generation Grubbs catalyst manufactured by Sigma-Aldrich.

[0042] In this invention, the solvent may be one or more of toluene, acetone, and tetrahydrofuran, preferably toluene.

[0043] In this invention, the cycloolefin / epoxy resin mixture preferably also includes other additives.

[0044] The other additives are generally commercially available conventional prepreg resin additives, such as one or more of defoamers, toughening agents, tackifiers, leveling agents, and coupling agents.

[0045] In this invention, the liquid epoxy resin is preferably in the form of 10-40 parts by weight, for example, 15 parts, 20 parts, 25 parts, 28 parts, 30 parts, 35 parts or 38 parts.

[0046] In this invention, the weight percentage of the solid epoxy resin is preferably 60-100 parts, for example 70 parts, 75 parts, 80 parts, 85 parts, 90 parts or 95 parts.

[0047] In this invention, the weight ratio of the liquid epoxy resin to the solid epoxy resin can be (0-45):(55-100), preferably (0-30):(70-100), for example 20:80, 28:72 or 10:90.

[0048] In this invention, the weight percentage of the cyclic olefin resin is preferably 6-22 parts, for example 8 parts, 10 parts, 12 parts, 14 parts, 16 parts, 18 parts or 20 parts.

[0049] In this invention, the curing agent is preferably 1-4 parts by weight, for example 1.5 parts, 2 parts, 2.8 parts, 3.1 parts, 3.4 parts or 3.6 parts.

[0050] In this invention, the weight of the accelerator is preferably 1-4 parts, for example 1.5 parts, 2 parts, 2.8 parts, 3.1 parts, 3.4 parts or 3.6 parts.

[0051] In this invention, the catalyst is preferably 0.001 to 0.008 parts by weight, for example 0.0015 parts, 0.0025 parts, 0.003 parts, 0.0035 parts, 0.004 parts, 0.0045 parts, 0.005 parts, 0.006 parts, 0.007 parts or 0.0075 parts.

[0052] In this invention, the solvent is preferably 40-60 parts by weight, for example 45 parts, 50 parts, 55 parts or 58 parts.

[0053] In this invention, when the cycloolefin / epoxy resin mixture also includes other additives, the weight parts of the other additives can be 0-5 parts, for example 1 part, 2 parts, 3 parts, 4 parts or 4.5 parts.

[0054] The present invention also provides a method for preparing the cyclic olefin / epoxy resin mixture as described above, comprising the following steps:

[0055] S1. The solid epoxy resin is melted, cooled for the first time, mixed with the solvent, and cooled for the second time to obtain mixture A;

[0056] S2. The mixture A is mixed with the liquid epoxy resin and the cyclic olefin resin to obtain mixture B;

[0057] S3. The mixture B is mixed with the curing agent, the accelerator and the catalyst to obtain the cyclic olefin / epoxy resin mixture.

[0058] In S1, the melting temperature can be 90-120°C, preferably 90-110°C, for example 100°C.

[0059] In S1, the temperature after the first cooling can be 70-100℃, preferably 70-90℃, such as 75℃, 80℃ or 85℃.

[0060] In S1, the temperature after the second cooling is generally room temperature, for example, 15-30℃, preferably 20-30℃, such as 25℃ or 28℃.

[0061] In S2, preferably, the mixture A is mixed sequentially with the liquid epoxy resin and the cyclic olefin resin to obtain mixture B.

[0062] The present invention also provides a fiber prepreg comprising the cyclic olefin / epoxy resin mixture and reinforcement as described above;

[0063] The weight ratio of the cyclic olefin / epoxy resin mixture to the reinforcement is (0.3-0.9):1.

[0064] In this invention, the weight ratio of the cycloolefin / epoxy resin mixture to the reinforcement is preferably (0.33-0.82):1, for example 25:75 or 45:55.

[0065] In this invention, the reinforcing material can be a fiber conventional in the art, such as organic fiber and / or inorganic fiber.

[0066] The organic fiber may be one or more of carbon fiber, aramid fiber and aromatic polyamide fiber.

[0067] The inorganic fiber may be glass fiber and / or basalt fiber.

[0068] The present invention also provides a method for preparing a fiber prepreg, which includes the following steps: impregnating the reinforcing body with the cyclic olefin / epoxy resin mixture as described above, and then removing the solvent;

[0069] The solvent removal temperature is 120-160℃;

[0070] The solvent removal time is 60-280 seconds.

[0071] In this invention, the solvent removal temperature is preferably 120-150°C, for example 130°C or 140°C.

[0072] In this invention, the solvent removal time is preferably 80-200s, for example 100s, 130s, 150s, 170s or 190s.

[0073] The present invention also provides a composite material comprising fibers and a three-dimensional network structure formed on the surface of the fibers by crosslinking and polymerization of a cyclic olefin / epoxy resin mixture as described above.

[0074] In this invention, the fiber can be a conventional fiber in the art, such as carbon fiber.

[0075] The present invention also provides a method for preparing a composite material, the steps of which include: curing the fiber prepreg as described above into a mold.

[0076] In this invention, the curing process for curing molding can be heating at 70-90℃ for 0.8-1.2h, heating at 90-120℃ for 0.8-1.2h, heating at 110-130℃ for 0.8-1.2h, or heating at 140-160℃ for 0.8-1.2h.

[0077] In this invention, preferably, the curing process is heating at 80°C for 1 hour, heating at 100°C for 1 hour, heating at 120°C for 1 hour, and heating at 140°C for 1 hour.

[0078] In this invention, the curing pressure can be 0.5-2 MPa, for example 1 MPa.

[0079] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0080] The reagents and raw materials used in this invention are all commercially available.

[0081] The positive and progressive effects of this invention are as follows:

[0082] (1) The components in the cyclic olefin / epoxy resin mixture of the present invention work together to obtain a cyclic olefin / epoxy resin mixture that can overcome many defects in the preparation of prepreg by solution impregnation method.

[0083] (2) Based on the solution impregnation method, the prepreg prepared using the cyclic olefin / epoxy resin mixture obtained by this invention enriches the process, formulation, and performance of the prepreg. On the one hand, it avoids the problems of poor processability, decreased product quality, and increased costs that may result from adding various additives. On the other hand, after compounding, the impact strength of the prepreg is improved to a certain extent. Detailed Implementation

[0084] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.

[0085] In the following examples and comparative examples, "parts" refers to "parts by weight".

[0086] The key raw material manufacturers and their brands are as follows:

[0087] Liquid epoxy resins: Bisphenol A type epoxy YN1828, epoxy value (0.48-0.51), viscosity at 25℃ is 11000-15000 cPs, produced by Jiangsu Yangnong Chemical; Bisphenol F type epoxy NPEF-170, epoxy value (0.56-0.63), viscosity at 25℃ is 2000-5000 cPs, produced by Nan Ya; Glycidylamine type epoxy resin (4,4-diaminodiphenylmethane tetraglycidylamine) S720, epoxy value (0.83-0.94), viscosity at 25℃... The viscosity at 25℃ is 3000-6000 cPs, produced by Nantong Xinxina; glycidyl ester type epoxy resin (4,5-epoxyhexane-1,2-dicarboxylic acid diglycidyl ester) S186, epoxy value (0.83-1), viscosity at 25℃ is 2000-3500 cPs, produced by Nantong Xinxina; alicyclic epoxy resin (1,2-epoxy-4-vinylcyclohexane) S21, epoxy value (0.7-0.76), viscosity at 25℃ is 300-450 cPs, produced by Nantong Xinxina;

[0088] Solid epoxy resins: Bisphenol A type epoxy YN2301, epoxy value (0.21), softening point 66℃, produced by Jiangsu Yangnong Chemical; Bisphenol A type epoxy NPES301, epoxy value (0.2-0.22), softening point 63℃, produced by Nan Ya; Phenolic epoxy (o-cresol epoxy resin) NPCN701, epoxy value (0.46-0.53), softening point 62℃, produced by Nan Ya; Phenolic epoxy (o-cresol epoxy resin) NPCN703, epoxy value (0.44-0.51), softening point 76℃, produced by Nan Ya.

[0089] Dicyclopentadiene is a commercially available product, manufactured by Guangdong Xinhua Yue Petrochemical Co., Ltd.

[0090] The preparation process of tricyclopentadiene (TCPD) used in this invention is as follows:

[0091] (1) 5 kg of the above-mentioned dicyclopentadiene (DCPD) from Guangdong Xinhua Yue Petrochemical Co., Ltd. was added into the reactor and heated to 200°C under nitrogen protection for 0.5 h to obtain a liquid mixture of DCPD, TCPD, TeCPD and PCPD.

[0092] (2) Cool the liquid mixture to 120°C and feed it into the first distillation column for negative pressure distillation. The substance obtained at the top of the column is DCPD, and the bottom of the column is a mixture of TCPD, TeCPD and PCPD. The bottom material is transported to the second distillation column for further negative pressure distillation. The substance obtained at the top of the column is TCPD.

[0093] The Grubbs catalyst used in this invention is manufactured by Sigma-Aldrich and is a second-generation Grubbs catalyst.

[0094] Example 1

[0095] Preparation of cycloolefin / epoxy resin mixture: 80 parts of solid epoxy resin were melted at 100°C; after cooling to 80°C, 50 parts of toluene were added, stirred evenly, and then cooled to 28°C. 20 parts of liquid epoxy resin and 10 parts of dicyclopentadiene were added sequentially and stirred evenly. Then, 3.4 parts of dicyandiamide curing agent, 1.15 parts of 2-methylimidazole accelerator, and 0.0025 parts of Grubbs 2 catalyst were added. nd Stir again until homogeneous and set aside; the viscosity (25℃) of the obtained cycloolefin / epoxy resin mixture is 7300 cPs.

[0096] Preparation of fiber prepreg: The carbon fiber cloth, which has been pre-cut to a certain size, is laid flat on the release paper. The fiber cloth is impregnated with a certain amount of the above prepreg resin mixture (resin mass: fiber mass = 35:65 after solvent removal). The solvent is removed in an oven at 150℃ for 80 seconds to obtain the prepreg product.

[0097] Composite material preparation: Several pieces of carbon fiber prepreg are molded into carbon fiber composite material sheets under the process conditions of 80℃ / 1h+100℃ / 1h+120℃ / 1h+140℃ / 1h and pressure of 1MPa.

[0098] Example 2

[0099] Preparation of cycloolefin / epoxy resin mixture: 100 parts of solid epoxy resin were melted at 90°C; after cooling to 70°C, 55 parts of toluene were added, stirred evenly, and then cooled to 28°C. 20 parts of dicyclopentadiene were added sequentially and stirred evenly. Then, 2.8 parts of dicyandiamide curing agent, 1.02 parts of 2-methylimidazole accelerator, and 0.005 parts of Grubbs 2 catalyst were added. nd Stir again until homogeneous and set aside; the viscosity (25℃) of the obtained cycloolefin / epoxy resin mixture is 8500 cPs.

[0100] Preparation of fiber prepreg: The carbon fiber cloth, which has been pre-cut to a certain size, is laid flat on the release paper. The fiber cloth is impregnated with a certain amount of the above prepreg resin mixture (resin mass: fiber mass = 40:60 after solvent removal). The solvent is removed in an oven at 130℃ for 150 seconds to obtain the prepreg product.

[0101] Composite material preparation: Several pieces of carbon fiber prepreg are molded into carbon fiber composite material sheets under the process conditions of 80℃ / 1h+100℃ / 1h+120℃ / 1h+140℃ / 1h and pressure of 1MPa.

[0102] Example 3

[0103] Preparation of cycloolefin / epoxy resin mixture: 72 parts of solid epoxy resin were melted at 100°C; after cooling to 70°C, 50 parts of toluene were added, stirred evenly, and then cooled to 28°C. 28 parts of liquid epoxy resin and 6 parts of dicyclopentadiene were added sequentially and stirred evenly. Then, 3.6 parts of dicyandiamide curing agent, 1.21 parts of 2-methylimidazole accelerator, and 0.0015 parts of Grubbs 2 catalyst were added. nd Stir again until homogeneous and set aside; the viscosity (25℃) of the obtained cycloolefin / epoxy resin mixture is 6300 cPs.

[0104] Preparation of fiber prepreg: The carbon fiber cloth, which has been pre-cut to a certain size, is laid flat on the release paper. The fiber cloth is impregnated with a certain amount of the above prepreg resin mixture (resin mass: fiber mass = 40:60 after solvent removal). The solvent is removed in an oven at 140℃ for 130 seconds to obtain the prepreg product.

[0105] Composite material preparation: Several pieces of carbon fiber prepreg are molded into carbon fiber composite material sheets under the process conditions of 80℃ / 1h+100℃ / 1h+120℃ / 1h+140℃ / 1h and pressure of 1MPa.

[0106] Example 4-11

[0107] The main conditional parameters in Examples 4-11 are listed in Tables 1-2 below, and the other conditional parameters are the same as those in Example 1.

[0108] Comparative Example 1

[0109] Preparation of cycloolefin / epoxy resin mixture: 100 parts of solid epoxy resin were melted at 100℃; after cooling to 80℃, 50 parts of toluene were added, stirred evenly, and then cooled to 28℃. 50 parts of dicyclopentadiene were added sequentially and stirred evenly. Then, 2.8 parts of dicyandiamide curing agent, 1.02 parts of 2-methylimidazole accelerator, and 0.005 parts of Grubbs 2 catalyst were added. nd Stir again until homogeneous and set aside; the viscosity (25℃) of the obtained cycloolefin / epoxy resin mixture is 210 cPs.

[0110] Preparation of fiber prepreg: The carbon fiber cloth, which has been pre-cut to a certain size, is laid flat on the release paper. The fiber cloth is impregnated with a certain amount of the above prepreg resin mixture (resin mass: fiber mass = 15:85 after solvent removal). The solvent is removed in an oven at 150℃ for 80 seconds. Due to the high DCPD content and low viscosity of the resin mixture, the resin content in the prepreg product is only 15%. The fiber surface is severely lacking in adhesive, resulting in poor workability in the later stages.

[0111] Comparative Example 2

[0112] Preparation of cycloolefin / epoxy resin mixture: 80 parts of solid epoxy resin were melted at 100°C; after cooling to 80°C, 50 parts of toluene were added, stirred evenly, and then cooled to 28°C. 20 parts of liquid epoxy resin and 10 parts of dicyclopentadiene were added sequentially and stirred evenly. Then, 3.4 parts of dicyandiamide curing agent, 1.15 parts of 2-methylimidazole accelerator, and 0.0025 parts of Grubbs 2 catalyst were added. nd Stir again until homogeneous and set aside; the viscosity (25℃) of the obtained cycloolefin / epoxy resin mixture is 6900 cPs.

[0113] Preparation of fiber prepreg: The carbon fiber cloth, which has been pre-cut to a certain size, is laid flat on the release paper. The fiber cloth is impregnated with a certain amount of the above-mentioned prepreg resin mixture (resin mass: fiber mass = 35:65 after solvent removal). The solvent is removed in an oven at 150℃ for 300 seconds. The solvent removal time is long, and the product is harder than the qualified prepreg product. It lacks operability in the later stage and cannot obtain a qualified prepreg product.

[0114] Comparative Example 3

[0115] Preparation of cycloolefin / epoxy resin mixture: 80 parts of solid epoxy resin were melted at 100℃; after cooling to 80℃, 20 parts of toluene were added, stirred evenly, and then cooled to 28℃. 20 parts of liquid epoxy resin and 10 parts of dicyclopentadiene were added sequentially and stirred evenly. Then, 3.4 parts of dicyandiamide curing agent, 1.15 parts of 2-methylimidazole accelerator, and 0.0025 parts of Grubbs 2 catalyst were added. nd Stir again until homogeneous and set aside; the viscosity (25℃) of the obtained cyclic olefin / epoxy resin mixture is 21000 cPs.

[0116] Preparation of finished fiber prepreg: Pre-cut carbon fiber cloth of a certain size is laid flat on release paper. A certain amount of the aforementioned prepreg resin mixture is used to impregnate the fiber cloth (resin mass: fiber mass = 35:65 after solvent removal). The solvent is removed in a 150℃ oven for 80 seconds. However, a qualified prepreg product cannot be obtained. The high viscosity of the cycloolefin / epoxy resin mixture causes resin loss in some areas and resin enrichment in others during impregnation, resulting in an uneven impregnation compared to qualified prepreg products.

[0117] Comparative Example 4

[0118] Preparation of cycloolefin / epoxy resin mixture: 80 parts of solid epoxy resin were melted at 100°C; after cooling to 70°C, 55 parts of toluene were added, stirred evenly, and then cooled to 28°C. 20 parts of liquid epoxy resin and 30 parts of dicyclopentadiene were added sequentially and stirred evenly. Then, 3.1 parts of dicyandiamide curing agent, 1.08 parts of 2-methylimidazole accelerator, and 0.0075 parts of Grubbs 2 catalyst were added. nd Stir again until well mixed, and set aside.

[0119] Preparation of fiber prepreg: The carbon fiber cloth, which has been pre-cut to a certain size, is laid flat on the release paper. The fiber cloth is impregnated with a certain amount of the above prepreg resin mixture (resin mass: fiber mass = 65:35 after solvent removal). The solvent is removed in an oven at 150℃ for 80 seconds. During the preparation process, excess resin drips from the fiber cloth, and qualified prepreg products cannot be obtained. Compared with qualified prepreg products, the resin distribution is obviously uneven and the stability of resin content cannot be guaranteed.

[0120] Comparative Examples 5-9

[0121] The main conditional parameters in Comparative Examples 5-9 are listed in Tables 1-2 below, and the other conditional parameters are the same as those in Example 1.

[0122] During the experiment, it was found that:

[0123] In Comparative Example 6, the solid epoxy was cooled to 50°C before the solvent was added and then toluene was added. At this point, the solid resin could not be completely dissolved in the toluene solvent, and there were undissolved solid epoxy particles in the resin system, making it impossible to conduct subsequent experiments.

[0124] In Comparative Example 7, dicyclopentadiene (DCPD) reacted directly with the Grubbs second-generation catalyst, making subsequent experiments impossible.

[0125] In Comparative Example 8, the solvent removal process was too time-consuming and inefficient, so no further reaction was carried out.

[0126] The cyclic olefin / epoxy resin mixture prepared in Comparative Example 9 had low viscosity and high surface tack of the prepreg. During the preparation of the composite board, severe resin flow occurred. Tests showed that the resin content in the prepared composite board was 23 wt%, which resulted in defects and poor mechanical properties.

[0127] The main conditional parameters involved in Examples 1-11 and Comparative Examples 1-9 are listed in Tables 1-2 below.

[0128] Table 1

[0129]

[0130]

[0131]

[0132] Table 2

[0133]

[0134] Note: In Table 2, " / " indicates that subsequent experiments cannot be conducted, so this condition is not involved.

[0135] Effect Example 1: Prepreg Impact Strength Test Test Object: Carbon fiber composite material sheets prepared in Examples 1-5 and Comparative Examples 1-9.

[0136] Test method: The impact strength of the sheet metal is tested according to "Cantilever beam impact strength test ISO 180". The test standards for tensile strength, tensile modulus, and elongation at break are ASTM D3039.

[0137] Test results are shown in Table 3 below.

[0138] Table 3

[0139]

[0140]

[0141] Note: In Table 3, "-" indicates that the data was not calculated, and " / " indicates that the data could not be measured.

[0142] A comprehensive analysis of the data in Tables 1-3 above yields the following results:

[0143] (1) According to the data of Comparative Example 1, if the proportion of dicyclopentadiene added in the cyclic olefin / epoxy resin mixture is too high, it cannot be formed into fiber prepreg in the final stage, resulting in the inability to obtain composite board with high impact strength.

[0144] (2) According to the data of Comparative Examples 1 and 4, in the process of preparing fiber prepreg, if the ratio of resin to fiber after solvent removal is too high or too low, the fiber prepreg cannot be formed, resulting in the inability to obtain composite board with high impact strength.

[0145] (3) According to the data of Comparative Example 3, if the amount of solvent added to the cycloolefin / epoxy resin mixture is too small, even if the substances in the mixture are uniformly dispersed, it will cause insufficient fiber impregnation in the later stage, and the fiber prepreg will not be formed in the final stage, resulting in the inability to obtain a composite board with high impact strength.

[0146] In addition, the inventors also discovered during their experimental research that if the amount of solvent added is too high in the process of preparing cycloolefin / epoxy resin mixture, it will not only waste solvent but also increase the difficulty of subsequent solvent removal. Furthermore, due to the low viscosity, the mixture is prone to flow out after the fiber is impregnated in the later stage.

[0147] (4) According to the data of Comparative Example 5, if dicyclopentadiene and catalyst are not added to the cycloolefin / epoxy resin mixture, it is impossible to obtain a composite board with high impact strength.

[0148] (5) According to the data of comparative examples 2, 6 and 8, if the process temperature is set too high or the time is too long in the later stage of preparing fiber prepreg products, it will cause the resin system to react and fail to prepare qualified fiber prepreg products.

[0149] In addition, the inventors also discovered during their experimental research that if the process temperature is too low or the time is too short in the later stage of solvent removal and fiber prepreg preparation, the solvent removal purpose cannot be effectively achieved.

[0150] (6) According to the data of Comparative Examples 7 and 9, improper handling of the mixture preparation process, the timing and order of adding each component, and the solution temperature setting may cause premature reaction, making it impossible to obtain composite boards with high impact strength.

Claims

1. A fibre prepreg, characterised in that, It comprises a cyclic olefin / epoxy resin mixture and a reinforcing body; The weight ratio of the cyclic olefin / epoxy resin mixture and the reinforcing body is (0.3-0.9):1; The cyclic olefin / epoxy resin mixture comprises the following components in total 100 parts by weight of liquid epoxy resin and solid epoxy resin: Liquid epoxy resin: 0-28 parts by weight; the epoxy value of the liquid epoxy resin is 0.41-1.0; Solid epoxy resin: 72-100 parts by weight; the epoxy value of the solid epoxy resin is 0.12-0.6; Cyclic olefin resin: 10-25 parts by weight; the cyclic olefin resin is one or more of dicyclopentadiene, dicyclopentadiene polymer, norbornene and ethylidene norbornene; Curing agent: 1-5 parts by weight; Promoter: 1-5 parts by weight; Catalyst: 0.003-0.01 parts by weight; Solvent: 40-70 parts by weight; The viscosity of the cyclic olefin / epoxy resin mixture at 25°C is 5000-9000 cPs; The preparation method of the cyclic olefin / epoxy resin mixture comprises the following steps: S1, the solid epoxy resin is melted, cooled for the first time, mixed with the solvent, and cooled for the second time to obtain a mixture A; S2, the mixture A is mixed with the liquid epoxy resin, the cyclic olefin resin to obtain a mixture B; S3, the mixture B is mixed with the curing agent, the promoter and the catalyst to obtain the cyclic olefin / epoxy resin mixture; In S1, the temperature after the first cooling is 70-100°C; The preparation method of the fiber prepreg comprises the following steps: after the cyclic olefin / epoxy resin mixture is impregnated into the reinforcing body, the solvent is removed, and the fiber prepreg is obtained; The temperature for removing the solvent is 120-160°C; The time for removing the solvent is 60-280s.

2. The fiber prepreg according to claim 1, wherein The cyclic olefin / epoxy resin mixture satisfies one or more of the following conditions a-m: a, the viscosity of the cyclic olefin / epoxy resin mixture at 25°C is 6000-9000 cPs; b, the epoxy value of the liquid epoxy resin is 0.41-0.85; c, the viscosity of the liquid epoxy resin at 25°C is 200-18000 cPs; d, the epoxy value of the solid epoxy resin is 0.12-0.53; e, the softening point of the solid epoxy resin at 25°C is 50-90°C; f, the cyclic olefin resin is dicyclopentadiene; g, when the cyclic olefin resin comprises dicyclopentadiene polymer, the dicyclopentadiene polymer is one or more of tricyclopentadiene, tetracyclopentadiene and pentacyclopentadiene; h, the liquid epoxy resin or the solid epoxy resin is one or more of glycidyl ether type epoxy resin, glycidyl amine type epoxy resin, glycidyl ester epoxy resin and alicyclic epoxy resin; i, the curing agent is one or more of aliphatic amine, aromatic amine, dicyandiamide, imidazole, organic acid anhydride, organic hydrazide and Lewis acid; j. the accelerator is one or more of imidazole compounds and derivatives and salts thereof, urea derivatives, organic guanidine derivatives, phosphorus-containing compounds, transition metal complexes and composite accelerators, tertiary amines and tertiary amine salts, quaternary phosphonium salts, Lewis acid-amine complexes, and acetylacetone transition metal complexes; k. the catalyst is a water and oxygen resistant type catalyst capable of curing the cyclic olefin resin in an air atmosphere; l. the solvent is one or more of toluene, acetone, and tetrahydrofuran; m. the cyclic olefin / epoxy resin mixture further includes other additives; the other additives are one or more of defoaming agents, toughening agents, tackifiers, leveling agents, and coupling agents.

3. The fiber prepreg according to claim 2, wherein, The cyclic olefin / epoxy resin mixture satisfies one or more of the following conditions a-g: a. the viscosity of the cyclic olefin / epoxy resin mixture at 25°C is 6300 cPs, 6700 cPs, 6900 cPs, 7300 cPs, 7800 cPs, 8000 cPs, 8500 cPs, or 8600 cPs; b. the liquid epoxy resin has an epoxy value of 0.48-0.51, 0.56-0.63, 0.7-0.76, or 0.83-0.94; c. the viscosity of the liquid epoxy resin at 25°C is 200-14000 cPs; d. the solid epoxy resin has an epoxy value of 0.2-0.22 or 0.46-0.53; e. the softening point of the solid epoxy resin at 25°C is 62°C, 63°C, 66°C, 70°C, 75°C, 76°C, 80°C, 85°C, or 87°C; f. the catalyst is a ruthenium-based catalyst; g. the solvent is toluene.

4. The fiber prepreg according to claim 2, wherein The cyclic olefin / epoxy resin mixture satisfies one or more of the following conditions a-c: a. the viscosity of the liquid epoxy resin at 25°C is 300-450 cPs or 2000-5000 cPs; b. the liquid epoxy resin has an epoxy value of 0.83-1; c. the solid epoxy resin has an epoxy value of 0.21 or 0.44-0.

51.

5. The fiber prepreg according to claim 2, wherein The viscosity of the liquid epoxy resin at 25°C is 3000-6000 cPs.

6. The fiber prepreg according to claim 2, wherein The viscosity of the liquid epoxy resin at 25°C is 2000-3500 cPs or 11000-15000 cPs.

7. The fiber prepreg according to any one of claims 2-6, wherein, The cyclic olefin / epoxy resin mixture satisfies one or more of the following conditions a-e: a. the glycidyl ether type epoxy resin is one or more of bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol AD type epoxy resin, and phenolic epoxy resin; b. the glycidyl amine type epoxy resin is one or more of 4.4-diaminodiphenylmethane tetraglycidyl amine, diglycidyl-p-aminophenol, triglycidyl-p-aminophenol, and tetraglycidyl diaminodiphenylmethane; c. the glycidyl ester epoxy resin is one or more of 4,5-epoxyhexane-1,2-dicarboxylic acid diglycidyl ester, isophthalic acid diglycidyl ester, tetrahydrophthalic acid diglycidyl ester, and hexahydrophthalic acid diglycidyl ester; d. the alicyclic epoxy resin is one or more of 1,2-epoxy-4-vinylcyclohexane, 3,4-epoxycyclohexane carboxylic acid methyl ester, bis((3,4-epoxycyclohexyl)methyl) adipate, 3,4-epoxycyclohexylmethyl methacrylate, and N,N,N,N,-tetraepoxypropyl-4,4-diaminodiphenylmethane; e. the catalyst is a Grubbs-type catalyst or a Hoveyda-Grubbs-type catalyst.

8. The fiber prepreg according to claim 7, wherein, The glycidyl ether type epoxy resin is one of a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a bisphenol S type epoxy resin, a bisphenol AD type epoxy resin, or a phenol-aldehyde epoxy resin.

9. The fiber prepreg according to claim 1, wherein, It meets one or more of the following conditions a-i; a. the liquid epoxy resin is 10-28 parts by weight; b. the solid epoxy resin is 72-90 parts by weight; c. the parts by weight ratio of the liquid epoxy resin to the solid epoxy resin is (0-28):(72-100); d. the cycloolefin resin is 12 parts, 14 parts, 16 parts, 18 parts, or 20 parts by weight; e. the curing agent is 1-4 parts by weight; f. the accelerator is 1-4 parts by weight; g. the catalyst is 0.003-0.008 parts by weight; h. the solvent is 40-60 parts by weight; i. when other additives are also included in the cycloolefin / epoxy resin mixture, the parts by weight of the other additives is 0-5 parts.

10. The fiber prepreg according to claim 9, wherein, The cycloolefin / epoxy resin mixture meets one or more of the following conditions a-g; a. the liquid epoxy resin is 15 parts, 20 parts, 25 parts, 28 parts by weight; b. the solid epoxy resin is 75 parts, 80 parts, 85 parts, 90 parts, or 95 parts by weight; c. the curing agent is 1.5 parts, 2 parts, 2.8 parts, 3.1 parts, 3.4 parts, or 3.6 parts by weight; d. the accelerator is 1.5 parts, 2 parts, 2.8 parts, 3.1 parts, 3.4 parts, or 3.6 parts by weight; e. the catalyst is 0.003 parts, 0.0035 parts, 0.004 parts, 0.0045 parts, 0.005 parts, 0.006 parts, 0.007 parts, or 0.0075 parts by weight; f. the solvent is 45 parts, 50 parts, 55 parts, or 58 parts by weight; g. when other additives are also included in the cycloolefin / epoxy resin mixture, the parts by weight of the other additives is 1 part, 2 parts, 3 parts, 4 parts, or 4.5 parts.

11. The fiber prepreg according to claim 9, wherein The parts by weight ratio of the liquid epoxy resin to the solid epoxy resin is 20:80, 28:72, or 10:

90.

12. The fiber prepreg according to claim 1, wherein The method for preparing the cycloolefin / epoxy resin mixture meets one or more of the following conditions a-d; a. in S1, the temperature of melting is 90-120°C; b. in S1, the temperature after the first temperature drop is 70-90°C; c. in S1, the temperature after the second temperature drop is room temperature; d. the mixture A is mixed with the liquid epoxy resin and the cycloolefin resin in sequence to obtain mixture B.

13. The fiber prepreg according to claim 12, wherein, The preparation method of the cyclic olefin / epoxy resin mixture satisfies one or more of the following conditions a-c; a. In S1, the temperature of the melting is 90-110℃; b. In S1, the temperature after the first cooling is 75℃, 80℃ or 85℃; c. In S1, the temperature after the second cooling is 15-30℃.

14. The fiber prepreg according to claim 12, wherein, In S1, the temperature of the melting is 100℃; and / or, in S1, the temperature after the second cooling is 20-30℃.

15. The fiber prepreg according to claim 12, wherein In S1, the temperature after the second cooling is 25℃ or 28℃.

16. The fiber prepreg according to claim 1, wherein The weight ratio of the cyclic olefin / epoxy resin mixture and the reinforcing body is (0.33-0.82):

1.

17. The fiber prepreg according to claim 16, wherein The weight ratio of the cyclic olefin / epoxy resin mixture and the reinforcing body is 25:75 or 45:

55.

18. The fiber prepreg according to claim 16, wherein The reinforcing body is organic fiber and / or inorganic fiber.

19. The fiber prepreg according to claim 18, wherein, The organic fiber is aramid fiber and / or aromatic polyamide fiber; and / or, the inorganic fiber is one or more of carbon fiber, glass fiber and basalt fiber.

20. A method of making a fiber prepreg according to any one of claims 1-19, characterized in that, It comprises the following step: after the reinforcing body is impregnated with the cyclic olefin / epoxy resin mixture, the solvent is removed, and then the process is completed. The temperature of the solvent removal is 120-160℃. The time of the solvent removal is 60-280s.

21. The method of making a fiber prepreg according to claim 20, wherein, The temperature of the solvent removal is 120-150℃. and / or, the time of the solvent removal is 80-200s.

22. The method of making a fiber prepreg according to claim 20, wherein, The temperature of the solvent removal is 130℃ or 140℃. and / or, the time of the solvent removal is 100s, 130s, 150s, 170s or 190s.

23. A composite material, characterized by It comprises fibers and a three-dimensional network structure formed by cross-linking polymerization of the cyclic olefin / epoxy resin mixture in the fiber pre-preg on the surface of the fibers.

24. A method of making a composite material, characterized by, The steps of the process include: curing and molding the fiber pre-preg according to any one of claims 1-19, and then the process is completed.

25. The method of claim 24, wherein the composite material is prepared by a process comprising: The curing procedure of the curing and molding is heating at 70-90℃ for 0.8-1.2h, heating at 90-120℃ for 0.8-1.2h, heating at 110-130℃ for 0.8-1.2h, and heating at 140-160℃ for 0.8-1.2h.

26. The method of claim 24, wherein the composite material is prepared by a process comprising: The curing procedure of the curing and molding is heating at 80℃ for 1h, heating at 100℃ for 1h, heating at 120℃ for 1h, and heating at 140℃ for 1h.

27. The method of claim 24, wherein the composite material is prepared by a process comprising: The pressure of the curing and molding is 0.5-2MPa.

28. The method for preparing the composite material as described in claim 24, characterized in that, The pressure of the curing and molding is 1MPa.

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