Manufacturing method of composite prepreg with interface and matrix self-repairing capability

Abstract

The invention discloses a manufacturing method of a composite prepreg with interface and matrix self-repairing capability. Belongs to the technical field of composite material intermediate manufacturing. The preparation method comprises the following steps: mixing dicyclopentadiene and a catalyst thereof, and epoxy resin and a curing agent thereof to obtain a microcapsule active component; adding the mixture into a prepolymer solution used as a shell material, emulsifying, adjusting the pH value, heating and curing to finish the reaction, washing, filtering and drying to obtain microcapsules; mixing the epoxy resin with a catalyst in matrix resin to obtain prepreg resin; and controlling viscosity and curing degree to form a resin film or wet resin, and combining the resin film or wet resin with unidirectional fiber cloth and the like through a solvent or a hot melting method. By combining the characteristics of rapid prototyping and self-repairing of PDCPD and utilizing the interface repairing capability provided by the low-content epoxy resin in the formula, rapid and synchronous high-strength interface and matrix self-repairing which cannot be realized by the existing composite material is realized, and the defect that after a composite material structural part is damaged, the self-repairing performance of the composite material is greatly improved is overcome. And in-situ repair cannot be rapidly carried out.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite material intermediate manufacturing, and specifically relates to a method for manufacturing a composite material prepreg with interface and matrix self-repairing capabilities, which realizes the rapid and synchronous high-strength interface and matrix self-repairing that cannot be achieved by current composite materials. Background Art

[0002] The inherent three-dimensional cross-linked network structure of conventional thermosetting resins leads to high brittleness. As a result, composite materials prepared with them have low toughness, poor delamination resistance, and poor impact resistance. As a result, the materials often need repair and patching during service.

[0003] Polydicyclopentadiene (PDCPD) is a novel material currently emerging in the field of polymer materials. Research has shown that the PDCPD repair agent system is composed of dicyclopentadiene and a ruthenium-based catalyst. DCPD can undergo a ring-opening metathesis polymerization reaction with a Grubbs reagent, thereby repairing cracks. Currently, composite repair materials often utilize this method to prepare microcapsules for repair. However, conventional repair methods utilize only a single PDCPD repair agent system, which lacks significant interfacial bonding and material system diffusion with the original system, resulting in significant process-dependent repair efficiency. Furthermore, conventional methods, such as injection, often fail to achieve sufficient in-situ repair effectiveness using conventional microcapsules. Summary of the Invention

[0004] The purpose of the present invention is to address the problems existing in the above-mentioned prior art and provide a method for manufacturing a composite material prepreg with self-repairing capabilities of the interface and matrix; overcome the defect of the single function of the prior art, it has the characteristics of rapid prototyping and rapid self-repair, and utilizes the interface repair ability provided by the low content of epoxy resin in the formula to achieve rapid and synchronous high-strength interface and matrix self-repair that cannot be achieved by current composite materials, and overcome the technical problem of being unable to quickly perform in-situ rapid, high-efficiency and high-retention rate repair of composite material structural parts after damage and the problem of in-situ interface repair.

[0005] The object of the present invention is achieved through the following technical solutions: The present invention provides a method for manufacturing a composite material prepreg having interface and matrix self-repairing capabilities, the method comprising the following steps: (1) Dicyclopentadiene and its catalyst, epoxy resin and its curing agent (added to a mixing device) are uniformly mixed to obtain a self-repairing microcapsule active ingredient; (2) Preliminary polymerization of the polymer monomer aqueous solution used as the microcapsule shell material to obtain a (viscous and transparent) prepolymer solution; adding a certain proportion of surfactant to the prepolymer solution; adding at least one drop of defoaming agent to the polymer monomer aqueous solution used as the microcapsule shell material under stirring conditions, and emulsifying for a certain period of time to form a stable oil-in-water (O / W) emulsion; then adjusting the pH value of the emulsion to 3.0-7.0 with dilute acid, slowly heating and curing to terminate the reaction; washing, filtering, and drying the suspension containing microcapsules to obtain microcapsules; (3) The microcapsules and a catalyst matching the active ingredients of the microcapsules are mixed in a matrix resin system to obtain a prepreg resin; the viscosity and curing degree of the prepreg resin are then controlled to form a dry / semi-dry resin film or a wet resin, which is then impregnated with a unidirectional fiber cloth or a fabric fiber cloth by a solvent method or a hot melt method to obtain a composite material prepreg having interface and matrix self-healing capabilities. The matrix resin system may be an epoxy resin (liquid / solid), a curing agent (liquid / solid) system, or a polyurethane (isocyanate, polyol).

[0006] As an embodiment of the present invention, in step (1), the volume percentage of dicyclopentadiene and its catalyst in the self-repairing microcapsule active ingredients is 50-99.9%, and the balance is epoxy resin and its curing agent; in the dicyclopentadiene and its catalyst system, the weight percentage of dicyclopentadiene is 95-98%, and the weight percentage of ethylidene norbornene is 2-5%; in the epoxy resin and its curing agent system, the mixed system is composed of 100 parts of epoxy resin, 10-50 parts of epoxy resin curing agent, and 0-30 parts of epoxy resin accelerator in parts by weight. Preferably, in step (1), the dicyclopentadiene and its catalyst and the epoxy resin and its curing agent are uniformly mixed in a mixing device according to the volume ratio of dicyclopentadiene and its catalyst system to epoxy resin and its curing agent system: 80-99.9%, 0.1-20%. The 80-99.9% dicyclopentadiene and its catalyst system are composed of a mixed solution of 95-98% dicyclopentadiene and 2-5% ethylidene norbornene; the 0.1-20% epoxy resin and its curing agent system are composed of 100 parts of epoxy resin, 10-50 parts of epoxy resin curing agent, and 0-30 parts of epoxy resin accelerator in parts by weight.

[0007] As an embodiment of the present invention, in step (2), the polymer monomer aqueous solution is a monomer aqueous solution of melamine resin or urea-formaldehyde resin; the polymer monomers of the melamine resin are melamine and formaldehyde; the polymer monomers of the urea-formaldehyde resin are urea and formaldehyde.

[0008] As an embodiment of the present invention, in step (2), the reaction conditions of the preliminary polymerization are a temperature not higher than 85° C., a pH value of 7.0 to 11.0, and a reaction time of not less than 2 hours.

[0009] As one embodiment of the present invention, in step (2), the surfactant includes an oil-in-water (O / W) emulsifier.

[0010] As an embodiment of the present invention, in step (2), the amount of surfactant added is 0.1 wt%-2 wt% based on the weight percentage of the total weight of the prepolymer solution and the surfactant; the surfactant is selected from at least one of polyoxyethylene dehydrate esters, polyoxyethylene ethers, polyoxyethylene fatty amines, polyethylene glycol fatty acid esters, sodium oleate, sodium rosinate, sodium dodecylbenzene sulfonate, and dialkyl sulfosuccinates.

[0011] As an embodiment of the present invention, in step (2), the defoaming agent includes at least one of polysiloxane (such as polydimethylsiloxane), polyvinyl alcohol (PVA), and epoxysiloxane.

[0012] As an embodiment of the present invention, in step (2), the emulsification temperature is not less than 10°C and not more than 85°C, the emulsification speed is 100-6000 rpm; and the emulsification time is not less than 0.25 hours.

[0013] As an embodiment of the present invention, in step (2), the dilute acid is dilute sulfuric acid or dilute hydrochloric acid.

[0014] As an embodiment of the present invention, in step (2), the slowly heating rate is 0.25°C / min-10°C / min; the temperature is raised to 90-150°C for curing, and the time is not less than 0.5 hours.

[0015] Preferably, the microcapsule shell material is prepared by preliminarily polymerizing an aqueous solution of melamine resin (melamine and formaldehyde) or urea-formaldehyde resin (urea and formaldehyde) to obtain a viscous, transparent prepolymer solution. 0.1-2 wt% linear sodium dodecylbenzene sulfonate or other surfactant is then added to the melamine resin or urea-formaldehyde resin prepolymer solution. The active ingredient containing the microcapsules is then added to the prepolymer solution under stirring, followed by 1-2 drops of polydimethylsiloxane or other defoaming agent. The solution is emulsified for a specified period of time to form a stable oil-in-water (O / W) emulsion. The pH of the emulsion is then adjusted to 3.0-7.0 with dilute sulfuric acid or hydrochloric acid, and the reaction is cured by heating at a rate of 0.25-3°C / min. Finally, the suspension containing the microcapsules is washed, filtered, and dried to obtain the microcapsules. As an embodiment of the present invention, in step (2), the mass ratio of the self-repairing microcapsule active ingredient to the prepolymer solution containing a surfactant is 1-10:100.

[0016] As an embodiment of the present invention, in step (3), the weight percentage content of the microcapsules in the prepreg resin is 0.5-10%; the weight of the catalyst matching the active ingredient of the microcapsules is 1 / 1000-1 / 40000 of the weight of the microcapsules.

[0017] As an embodiment of the present invention, in step (3), the matrix resin system of the prepreg is one or more resin systems selected from epoxy resin, bismaleimide resin, cyanate resin, polyurethane resin, polyimide resin, unsaturated resin, and epoxy vinyl resin.

[0018] As an embodiment of the present invention, in step (3), the fiber cloth in the prepreg is a unidirectional cloth or a blended fabric of at least one of carbon fiber, glass fiber, aramid fiber, polyimide fiber, and ultra-molecular weight polyethylene fiber.

[0019] As one embodiment of the present invention, in step (3), the catalyst matching the microcapsule active ingredient is a catalyst solution prepared by dissolving Grubbs second-generation catalyst and tributyl phosphite in cyclohexylbenzene. Preferably, in the catalyst matching the microcapsule active ingredient, the mass ratio of the second-generation catalyst to cyclohexylbenzene is 1:100 to 1:400; and the mass ratio of the second-generation catalyst to tributyl phosphite is 1:0.05 to 1:0.1.

[0020] As an embodiment of the present invention, in step (3), the viscosity of the prepreg resin of the dry / semi-dry resin film is 6000-80000 mPa•s.

[0021] As an embodiment of the present invention, in step (3), the viscosity of the prepreg resin in a wet state is 1000-6000 mPa•s.

[0022] Preferably, in the step (3), the self-repairing microcapsules obtained in the step (2) and a catalyst matching the active ingredients of the microcapsules are mixed in the original resin system to obtain a prepreg resin; wherein the catalyst is prepared by dissolving a Grubbs second-generation catalyst and tributyl phosphite in cyclohexylbenzene to prepare a catalyst solution; finally, the viscosity and curing degree of the original resin system are controlled to form a dry or semi-dry resin film or a wet prepreg resin (wherein the viscosity of the dry or semi-dry resin film prepreg resin is 6000-80000 mPa•s; the viscosity of the wet prepreg resin is 1000-6000 mPa•s), and then impregnated with a unidirectional fiber cloth or a fabric fiber cloth by a solvent method or a hot melt method to manufacture a composite material prepreg with interface and matrix self-repairing ability. The specific manufacturing process is as follows. Figure 2 , Figure 3The original resin system is such as epoxy resin (liquid / solid), curing agent (liquid / solid) system or polyurethane (isocyanate, polyol).

[0023] The composite material prepreg produced by the method of the present invention also falls within the protection scope of the present invention.

[0024] The technical solution of the present invention adopts dicyclopentadiene and its catalyst system and epoxy resin and its curing agent system as the active ingredients of self-repairing microcapsules, and then premixes the capsules in prepolymer resins such as epoxy resin, so as to realize the function of self-repairing materials under the action of external forces (damage) and when cracks appear inside the composite material after damage, and to maintain mechanical properties. The present invention combines the characteristics of PDCPD's own rapid prototyping and self-repair, and at the same time utilizes the interface repair ability provided by the low content of epoxy resin in the formula to achieve rapid and synchronous high-strength interface and matrix self-repair that cannot be achieved by current composite materials, and overcomes the technical problem that composite material structures cannot be quickly repaired in situ and at the interface after damage. The multiple steps and technical features of the present invention are interrelated and synergistic, which has the effect of combining the advantages of all materials in the invention by leveraging their strengths and avoiding their weaknesses.

[0025] The present invention also points out that the prepreg and formulation are manufactured by combining resin and textile reinforcement. Furthermore, the present invention achieves the advantage of rapid interface repair, which is not available in existing patents. Therefore, through the design of the resin matrix formula, the present invention achieves rapid, efficient, and highly retentive in-situ repair and interface repair, which is unattainable with existing technologies, demonstrating originality and creativity.

[0026] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention uses dicyclopentadiene and its catalyst system and epoxy resin and its curing agent system as the active ingredients of self-repairing microcapsules, and then premixes the capsules into prepolymer resins such as epoxy resin, so as to realize the function of self-repairing materials under the action of external force (damage), and when cracks appear inside the composite material after damage, the composite material has the function of automatically repairing and maintaining mechanical properties.

[0027] (2) The present invention overcomes the defect of single function of the existing technology. By compounding dicyclopentadiene and its catalyst system with epoxy resin and its curing agent system, the present invention overcomes the shortcomings of poor interface bonding between PDCPD repair agent and conventional carbon fiber, glass fiber and other reinforced fiber composite materials, and low strength and stiffness of the repaired composite materials. The present invention realizes the correlation and synergy of the technical features of the formula, and achieves the synergistic effect of rapid prototyping and good interface bonding.

[0028] (3) The present invention combines the characteristics of PDCPD itself, such as rapid prototyping and self-repair, with the use of a low content of epoxy resin in the formula to overcome the disadvantage of weak interfacial bonding between PDCPD and conventional fibers and resins; it achieves rapid and synchronous high-strength interface and matrix self-repair that cannot be achieved by current composite materials, and overcomes the technical problem that composite material structural parts cannot be quickly repaired in situ after being damaged. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings: Figure 1 A schematic diagram of the repair principle of a composite material prepreg with self-repairing capabilities of the interface and matrix after damage; Figure 2 It is a prepreg film preparation process; Figure 3 This is a prepreg solution preparation process. DETAILED DESCRIPTION

[0030] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are intended to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of the present application. The raw materials used in the experiment are shown in Table 1.

[0031] Table 1 Raw materials used in the experiment

[0032] Example 1 This embodiment provides a method for manufacturing a composite material prepreg with self-repairing capabilities of the interface and matrix, comprising the following steps: (1) Dicyclopentadiene and its catalyst system and epoxy resin and its curing agent system are mixed evenly in a mixing device in a volume ratio of 99.9% and 0.1% to obtain a self-repairing microcapsule active ingredient.

[0033] The dicyclopentadiene and its catalyst system are composed of a mixed solution of 95% dicyclopentadiene and 5% ethylidene norbornene; The epoxy resin and its curing agent system is a monomer mixed system consisting of 100 parts of epoxy resin monomer E51, 20 parts of epoxy resin accelerator DMP30, and 10 parts of epoxy resin curing agent E100 (total 0.1%).

[0034] (2) Microcapsule shell material, which is prepared by preliminarily polymerizing a melamine resin (melamine and formaldehyde monomers) aqueous solution (temperature 80°C, pH = 7, polymerization for 2 h) to obtain a viscous and transparent prepolymer aqueous solution, and then adding 0.1 wt% linear sodium dodecylbenzene sulfonate to the melamine resin prepolymer aqueous solution; The microcapsule active ingredient (10 wt.%) was then added to the prepolymer solution of the microcapsule shell material under stirring. Two drops of polydimethylsiloxane were then added, and emulsification was performed (emulsification temperature 25°C, emulsification speed 500 rpm, emulsification time 20 minutes) to form a stable oil-in-water (O / W) emulsion. The emulsion's pH was then adjusted to 3 with dilute sulfuric acid, and the temperature was raised to 120°C at a rate of 1°C / min for 40 minutes for curing. After the curing reaction was complete, the suspension containing the microcapsules was washed, filtered, and dried to obtain the microcapsules.

[0035] (3) The self-healing microcapsules and the catalyst matching the active ingredients of the microcapsules were mixed in a high-toughness medium-temperature curing epoxy resin JTX135 resin to obtain a prepreg resin (the weight percentage of the microcapsules in the prepreg resin was 5%; the weight of the catalyst was 1 / 2000 of the weight of the microcapsules); wherein the catalyst was a catalyst solution prepared by dissolving Grubbs second-generation catalyst and tributyl phosphite in cyclohexylbenzene; finally, the viscosity of the original resin system was controlled to form a dry resin film, which was then impregnated with 24K carbon fiber yarn unidirectional cloth by hot melt method to obtain a composite material prepreg with interface and matrix self-healing capabilities.

[0036] In the catalyst matching the active ingredients of the microcapsule, the mass ratio of the Grubbs second-generation catalyst to tributyl phosphite is 1:0.05; the mass ratio of the Grubbs second-generation catalyst to cyclohexylbenzene is 1:100.

[0037] (4) Based on the above prepreg, a composite material flat plate was prepared using a molding process (125°C, 0.6 MPa, 2 h).

[0038] (5) Based on the ASTM D7136 drop hammer impact test, the above damage was repaired at 150℃, 0.6MPa, and mold pressing for 5min. The repair mechanism is as follows: Figure 1 shown.

[0039] Samples were then taken to test mechanical property retention. Specifically, tensile strength in the warp and weft directions was measured according to ASTM D3039. Furthermore, the impact test standard, according to ASTM D7316, employed a constant impact energy normalized by the test thickness. The thickness of each laminate was measured, and the required impact energy was calculated using the following formula.

[0040] E = CE·h; Where E represents the impact energy (J); CE is the ratio of the standard impact energy to the sample thickness, 6.7 J / mm; and h is the sample thickness (mm). The standard impact energy is achieved by adjusting the drop height of the hammer. The drop height is calculated using the following formula: H=E / (m d g); Where H is the height of the falling hammer (m), m d is the mass of the falling hammer (kg), g is the acceleration due to gravity, generally 9.8 m / s 2 .

[0041] After impact, the specimen was compressed at a loading rate of 1.25 mm / min according to ASTM D7137, and the residual compressive strength of the laminate was calculated according to the following formula.

[0042] ; Where, represents the ultimate compressive residual strength (MPa), represents the maximum force before failure (N), A represents the compressed cross-sectional area (mm 2 ).

[0043] Example 2 This embodiment relates to a method for manufacturing a composite material prepreg with self-repairing capabilities of the interface and matrix, comprising the following steps: (1) Dicyclopentadiene and its catalyst system and epoxy resin and its curing agent system are mixed evenly in a mixing device in a volume ratio of 80% and 20% to obtain a self-repairing microcapsule active ingredient.

[0044] The dicyclopentadiene and its catalyst system are composed of a mixed solution of 98% dicyclopentadiene and 2% ethylidene norbornene; The epoxy resin and its curing agent system is a monomer mixed system consisting of 100 parts of epoxy resin monomer E51, 20 parts of epoxy resin accelerator DMP30, and 10 parts of epoxy resin curing agent E100 (total 20%).

[0045] (2) Microcapsule shell material: a viscous and transparent prepolymer aqueous solution is obtained by preliminarily polymerizing an aqueous solution of a urea-formaldehyde resin (polymerization of urea and formaldehyde monomers) (temperature 80°C, pH = 7, polymerization for 2 h), and then adding 2 wt% of a polyoxyethylene ether oil-in-water (O / W) emulsifier to the urea-formaldehyde resin prepolymer aqueous solution; The active ingredient (5 wt.%) was then added to the prepolymer solution of the microcapsule shell material under stirring. One drop of polydimethylsiloxane defoamer was then added. The mixture was emulsified for a specified time (25°C, 500 rpm, 30 minutes) to form a stable oil-in-water (O / W) emulsion. The pH of the emulsion was then adjusted to 4 using dilute sulfuric acid or hydrochloric acid. The mixture was then heated to 120°C at a rate of 3°C / min and cured for 60 minutes to complete the curing reaction. The suspension containing the microcapsules was then washed, filtered, and dried to obtain the microcapsules.

[0046] (3) The self-healing microcapsules and the catalyst matching the active ingredients of the microcapsules were mixed in a high-toughness medium-temperature curing epoxy resin JTX135 to obtain a prepreg resin (the weight percentage of the microcapsules in the prepreg resin was 5%; the weight of the catalyst was 1 / 2000 of the weight of the microcapsules); wherein the catalyst was a catalyst solution prepared by dissolving Grubbs second-generation catalyst and tributyl phosphite in cyclohexylbenzene; finally, the viscosity and curing degree of the original resin system were controlled to form a dry prepreg resin film, which was then impregnated with 24K carbon fiber yarn unidirectional cloth by hot melt method to obtain a composite material prepreg with interface and matrix self-healing ability.

[0047] Among them, in the catalyst matching the microcapsule active ingredient, the mass ratio of Grubbs second-generation catalyst to cyclohexylbenzene is 1:400; the mass ratio of the second-generation catalyst to tributyl phosphite is 1:0.1.

[0048] (4) Based on the above prepreg, a composite material flat plate was prepared using a molding process (125°C, 0.6 MPa, 2 h).

[0049] (5) Based on the ASTM D7136 drop hammer impact test, the above damage was repaired at 150℃, 0.6MPa, and mold pressing for 10min. The repair mechanism is as follows: Figure 1 shown.

[0050] Samples were then taken to test mechanical property retention. Specifically, tensile strength in the warp and weft directions was measured according to ASTM D3039. Furthermore, the impact test standard, according to ASTM D7316, employed a constant impact energy normalized by the test thickness. The thickness of each laminate was measured, and the required impact energy was calculated using the following formula.

[0051] E = CE·h; Where E represents the impact energy (J); CE is the ratio of the standard impact energy to the sample thickness, 6.7 J / mm; and h is the sample thickness (mm). The standard impact energy is achieved by adjusting the drop height of the hammer. The drop height is calculated using the following formula: H=E / (md g); Where H is the height of the falling hammer (m), m d is the mass of the falling hammer (kg), g is the acceleration due to gravity, generally 9.8 m / s 2 .

[0052] After impact, the specimen was compressed at a loading rate of 1.25 mm / min according to ASTM D7137, and the residual compressive strength of the laminate was calculated according to the following formula.

[0053] ; Where, represents the ultimate compressive residual strength (MPa), represents the maximum force before failure (N), A represents the compressed cross-sectional area (mm 2 ).

[0054] Comparative Example 1 The damaged composite material prepared from carbon fiber reinforced epoxy resin prepreg (SCF40S-L5-24K / JXT135-133-34%-1000mm) was sampled without repair and the performance was tested according to the following method.

[0055] Specifically, the warp and weft tensile strength was tested according to ASTM D3039. Furthermore, the impact test standard, according to ASTM D7316, employed a constant impact energy normalized by the test thickness. The thickness of each laminate was measured, and the required impact energy was calculated using the following formula.

[0056] E = CE·h; Where E represents the impact energy (J); CE is the ratio of the standard impact energy to the sample thickness, 6.7 J / mm; and h is the sample thickness (mm). The standard impact energy is achieved by adjusting the drop height of the hammer. The drop height is calculated using the following formula: H=E / (m d g); Where H is the height of the falling hammer (m), m d is the mass of the falling hammer (kg), g is the acceleration due to gravity, generally 9.8 m / s 2 .

[0057] After impact, the specimen was compressed at a loading rate of 1.25 mm / min according to ASTM D7137, and the residual compressive strength of the laminate was calculated according to the following formula.

[0058] ; Where, represents the ultimate compressive residual strength (MPa), represents the maximum force before failure (N), A represents the compressed cross-sectional area (mm 2 ).

[0059] Comparative Example 2 The main difference between this comparative example and the embodiment is that melamine-formaldehyde resin (melamine resin MF) is used as the shell material and dicyclopentadiene (DCPD) is used as the core material, and microcapsules for self-healing materials are prepared by in-situ polymerization as reported in the literature.

[0060] (1) The microcapsule was synthesized as follows: 270 g of melamine formaldehyde prepolymer, 60 g of acrylic acid / acrylamide copolymer, and 1400 g of deionized water were placed in a cylindrical reactor and stirred and dissolved using a turbulent stirring paddle. Acetic acid was used to adjust the pH of the solution to 4.0. 65 g of the core material, dicyclopentadiene, was then added to the system and emulsified using an emulsifier at a constant speed and room temperature for 140 min. The water bath temperature was then raised to 65°C, and a turbulent stirring paddle was used to stir at a speed of 400 rpm. After the reaction continued for a period of time, the pH of the dispersed system was adjusted to 10 using a 20% mass fraction NaOH solution. The product was discharged and washed with deionized water.

[0061] (2) The self-healing microcapsules and the catalyst matching the active ingredients of the microcapsules were mixed in the original high-toughness medium-temperature curing epoxy resin JTX135 to obtain a prepreg resin (the weight percentage of the microcapsules in the prepreg resin was 5%; the weight of the catalyst was 1 / 2000 of the weight of the microcapsules); wherein the catalyst was a catalyst solution prepared by dissolving Grubbs second-generation catalyst and tributyl phosphite in cyclohexylbenzene; finally, the viscosity and curing degree of the original resin system were controlled to form a dry prepreg resin film, which was then impregnated with 24K carbon fiber yarn unidirectional cloth by hot melt method to obtain a composite material prepreg.

[0062] Among them, in the catalyst matching the microcapsule active ingredient, the mass ratio of Grubbs second-generation catalyst to cyclohexylbenzene is 1:400; the mass ratio of the second-generation catalyst to tributyl phosphite is 1:0.1.

[0063] (3) Based on the above-mentioned prepreg, a composite material flat plate was prepared using a molding process (125°C, 0.6 MPa, 2 h).

[0064] (4) The aforementioned damage was repaired by a drop hammer impact test based on ASTM D7136, then molded for 5 minutes at 150°C and 0.6 MPa. Samples were then taken to test mechanical property retention. Specifically, the warp and weft tensile strength was tested according to ASTM D3039. Furthermore, according to ASTM D7316, the impact standard test employed a constant impact energy normalized by the test thickness. The thickness of each laminate was measured, and the required impact energy was calculated using the following formula.

[0065] E = CE·h; Where E represents the impact energy (J); CE is the ratio of the standard impact energy to the sample thickness, 6.7 J / mm; and h is the sample thickness (mm). The standard impact energy is achieved by adjusting the drop height of the hammer. The drop height is calculated using the following formula: H=E / (m d g); Where H is the height of the falling hammer (m), m d is the mass of the falling hammer (kg), g is the acceleration due to gravity, generally 9.8 m / s 2 .

[0066] After impact, the specimen was compressed at a loading rate of 1.25 mm / min according to ASTM D7137, and the residual compressive strength of the laminate was calculated according to the following formula.

[0067] ; Where, represents the ultimate compressive residual strength (MPa), represents the maximum force before failure (N), A represents the compressed cross-sectional area (mm 2 ).

[0068] Comparative Example 3 This comparative example is the same as comparative example 2, and adopts melamine-formaldehyde resin (melamine resin MF) as the shell material and dicyclopentadiene (DCPD) as the core material as reported in the literature to prepare microcapsules for self-healing materials by in-situ polymerization.

[0069] (1) The microcapsule synthesis was as follows: 270 g of melamine formaldehyde prepolymer, 60 g of acrylic acid / acrylamide copolymer, and 1400 g of deionized water were placed in a cylindrical reactor and dissolved using a turbulent stirring paddle. Acetic acid was used to adjust the solution's pH to 4.0. 65 g of the core material, dicyclopentadiene, was then added to the system and emulsified using an emulsifier at a constant speed and room temperature for 140 min. The water bath temperature was then raised to 65°C, and stirring was continued at 400 rpm using a turbulent stirring paddle. After a period of continued reaction, the pH of the dispersed system was adjusted to 10 using a 20% (mass fraction) NaOH solution. The product was discharged and washed with deionized water.

[0070] (2) The self-healing microcapsules and the catalyst matching the active ingredients of the microcapsules were mixed in a high-toughness medium-temperature curing epoxy resin JTX135 to obtain a prepreg resin (the weight percentage of the microcapsules in the prepreg resin was 5%; the weight of the catalyst was 1 / 2000 of the weight of the microcapsules); wherein the catalyst was prepared by dissolving Grubbs second-generation catalyst and tributyl phosphite in cyclohexylbenzene, and simultaneously adding epoxy resin and its curing agent system to prepare a catalyst solution; finally, the viscosity and curing degree of the original resin system were controlled to form a dry prepreg resin glue; the membrane was then impregnated with 24K carbon fiber yarn unidirectional cloth by hot melt method to obtain a composite material prepreg.

[0071] The epoxy resin and its curing agent system is a monomer mixture system consisting of 100 parts of epoxy resin monomer E51, 20 parts of epoxy resin accelerator DMP30, and 10 parts of epoxy resin curing agent E100; and the volume ratio of the epoxy resin and its curing agent system to the self-healing microcapsule core material dicyclopentadiene is 1:4.

[0072] In the catalyst matching the microcapsule active ingredient, the mass ratio of the second-generation catalyst to cyclohexylbenzene is 1:400; the mass ratio of the second-generation catalyst to tributyl phosphite is 1:0.1.

[0073] (3) Based on the above-mentioned prepreg, a composite material flat plate was prepared using a molding process (125°C, 0.6 MPa, 2 h).

[0074] (4) The aforementioned damage was repaired by a drop hammer impact test based on ASTM D7136, then molded for 150 min at 150°C and 0.6 MPa. Samples were then taken to test mechanical property retention. Specifically, the warp and weft tensile strength was tested according to ASTM D3039. Furthermore, the impact standard test, based on ASTM D7316, employed a constant impact energy normalized by the test thickness. The thickness of each laminate was measured, and the required impact energy was calculated using the following formula.

[0075] The repair was performed using the aforementioned prepreg based on the HB / Z 410-2013 resin-based composite parts repair process standard.

[0076] Sampling was performed to test performance according to the following method.

[0077] Specifically, the warp and weft tensile strength was tested according to ASTM D3039. Furthermore, the impact test standard, according to ASTM D7316, employed a constant impact energy normalized by the test thickness. The thickness of each laminate was measured, and the required impact energy was calculated using the following formula.

[0078] E = CE·h; Where E represents the impact energy (J); CE is the ratio of the standard impact energy to the sample thickness, 6.7 J / mm; and h is the sample thickness (mm). The standard impact energy is achieved by adjusting the drop height of the hammer. The drop height is calculated using the following formula: H=E / (m d g); Where H is the height of the falling hammer (m), m d is the mass of the falling hammer (kg), g is the acceleration due to gravity, generally 9.8 m / s 2 .

[0079] After impact, the specimen was compressed at a loading rate of 1.25 mm / min according to ASTM D7137, and the residual compressive strength of the laminate was calculated according to the following formula.

[0080] ; Where, represents the ultimate compressive residual strength (MPa), represents the maximum force before failure (N), A represents the compressed cross-sectional area (mm 2 ).

[0081] The measured data of the above embodiments and comparative examples are shown in Table 2.

[0082] Table 2. Material performance comparison table

[0083] In summary, the composite prepreg of the present invention uses thermosetting resin prepolymers such as epoxy resin, polyurethane, unsaturated resin, epoxy vinyl, and bismaleimide resin as the prepreg resin material; fiber reinforcement materials such as carbon fiber and glass fiber as the fiber material; melamine (melamine-formaldehyde) resin (MF) and urea-formaldehyde (urea-formaldehyde) resin (UF) as the capsule shell material; dicyclopentadiene and its catalyst system and epoxy resin and its curing agent system as the self-healing microcapsule active ingredients. The capsules are then premixed into the prepreg resin such as epoxy resin, thereby achieving the function of self-healing material when cracks appear after damage to the composite material under external force (damage). The self-healing microcapsule active ingredients are mixed in a volume ratio of: 80-99.9% dicyclopentadiene system and 0.1-20% epoxy resin system. The present invention combines the rapid prototyping and self-repairing characteristics of PDCPD with the interface repair capabilities provided by the low content of epoxy resin in the formula to achieve rapid and synchronous high-strength interface and matrix self-repair that cannot be achieved with current composite materials, overcoming the technical problem that composite material structures cannot be quickly repaired in situ after being damaged.

[0084] The above describes specific embodiments of the present invention. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. The embodiments of this application and the features in the embodiments may be combined with each other in any manner unless there is a conflict.

Claims

1. A method for manufacturing a composite material prepreg with self-repairing ability of the interface and matrix, characterized in that: The method comprises the following steps: (1) Dicyclopentadiene and its catalyst are mixed with epoxy resin and its curing agent to obtain a self-repairing microcapsule active ingredient; (2) Preliminarily polymerizing the aqueous solution of polymer monomers used as microcapsule shell materials to obtain a prepolymer solution; A certain proportion of surfactant is added to the prepolymer solution; the self-repairing microcapsule active ingredient is added to the prepolymer solution containing the surfactant under stirring conditions, and at least one drop of defoaming agent is added, and emulsification is performed for a certain period of time to form a stable oil-in-water emulsion; the pH value of the emulsion is then adjusted to 3.0-7.0 with dilute acid, and the temperature is slowly raised to cure to terminate the reaction; the suspension containing the microcapsules is washed, filtered, and dried to obtain microcapsules; (3) The microcapsules and a catalyst matching the active ingredients of the microcapsules are mixed in a matrix resin system to obtain a prepreg resin; the viscosity and curing degree thereof are controlled to form a dry / semi-dry resin film or a wet resin, and then impregnated with a unidirectional fiber cloth or a fabric fiber cloth by a hot melt method or a solvent method to obtain a composite material prepreg having interface and matrix self-healing capabilities.

2. The method for producing a composite material prepreg according to claim 1, wherein: In step (1), the volume percentage of dicyclopentadiene and its catalyst in the self-repairing microcapsule active ingredients is 50-99.9%, and the balance is epoxy resin and its curing agent; In the dicyclopentadiene and catalyst system thereof, the weight proportion of dicyclopentadiene is 95-98%, and the weight proportion of ethylidene norbornene is 2-5%; The epoxy resin and its curing agent system comprises 100 parts of epoxy resin, 10-50 parts of epoxy resin curing agent and 0-30 parts of epoxy resin accelerator in parts by weight.

3. The method for producing a composite material prepreg according to claim 1, wherein: Step (2) also includes at least one of the following technical features: A1. The polymer monomer aqueous solution is a monomer aqueous solution of a melamine resin or a urea-formaldehyde resin; the polymer monomers of the melamine resin are melamine and formaldehyde; the polymer monomers of the urea-formaldehyde resin are urea and formaldehyde; A2, the reaction conditions of the preliminary polymerization are a temperature not greater than 85°C, a pH value of 7.0 to 11.0, and a reaction time of not less than 2 hours; A3, the surfactant includes an oil-in-water emulsifier; A4, based on the weight percentage of the total weight of the prepolymer solution and the surfactant, the amount of the surfactant added is 0.1wt%-2wt%; the surfactant is selected from at least one of polyoxyethylene dehydrate esters, polyoxyethylene ethers, polyoxyethylene fatty amines, polyethylene glycol fatty acid esters, sodium oleate, sodium rosinate, sodium dodecylbenzenesulfonate, and dialkyl sulfosuccinates; A5. The defoaming agent includes at least one of polysiloxane, polyvinyl alcohol, and epoxysiloxane; A6. The emulsification temperature is not less than 10°C and not more than 85°C, the emulsification speed is 100-6000 rpm; the emulsification time is not less than 0.25 hours; A7. The dilute acid is dilute sulfuric acid or dilute hydrochloric acid; A8. The heating rate of the slow heating is 0.25°C / min-10°C / min; the temperature is raised to 90-150°C for curing, and the curing time is not less than 0.5 hours.

4. The method for producing a composite material prepreg according to claim 1, wherein: In step (2), the mass ratio of the self-repairing microcapsule active ingredient to the prepolymer solution containing a surfactant is 1-10:

100.

5. The method for producing a composite material prepreg according to claim 1, wherein: In step (3), the weight percentage of the microcapsules in the prepreg resin is 0.5-10%; the weight of the catalyst matching the active ingredient of the microcapsules is 1 / 1000-1 / 40000 of the weight of the microcapsules.

6. The method for producing a composite material prepreg according to claim 1, wherein: Step (3) also includes at least one of the following technical features: B1. The matrix resin system of the prepreg is one or more of epoxy resin, bismaleimide resin, cyanate resin, polyurethane resin, polyimide resin, unsaturated resin and epoxy vinyl resin; B2. The fiber cloth in the prepreg is a unidirectional cloth or a blended fabric of at least one of carbon fiber, glass fiber, aramid fiber, polyimide fiber, and ultra-molecular weight polyethylene fiber; B3, the catalyst matching the active ingredient of the microcapsule is a catalyst solution prepared by dissolving Grubbs second-generation catalyst and tributyl phosphite in cyclohexylbenzene; B4. The prepreg resin viscosity of the dry / semi-dry resin film is 6000-80000 mPa•s; B5. The viscosity of the prepreg resin in wet form is 1000-6000 mPa•s.

7. The method for producing a composite material prepreg according to claim 6, wherein: The mass ratio of Grubbs second-generation catalyst, tributyl phosphite and cyclohexylbenzene is 1: (0.05~0.1): (100~400).

8. A composite material prepreg produced by the method according to any one of claims 1 to 7.

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