Method for manufacturing a composite prepreg with self-healing capability of interface and matrix

Abstract

The application discloses a kind of composite material prepreg manufacturing method with interface and substrate self-repairing ability;Belong to the technical field of composite material intermediate manufacturing.The application obtains microcapsule active ingredient by mixing dicyclopentadiene and its catalyst and epoxy resin and its curing agent;Add prepolymer solution used as shell material, emulsify, adjust pH, end reaction by temperature curing, wash, filter and dry to obtain microcapsule;Mix it and catalyst in matrix resin to obtain prepreg resin;Control viscosity and curing degree to form resin film or wet-state resin, manufacture by solvent or hot melt method combined with unidirectional fiber cloth etc.It is obtained immediately.The application combines the characteristics of PDCPD itself rapid forming and self-repairing, simultaneously utilizes the interface repair ability provided by low content epoxy resin in formula, realizes the rapid synchronous high-strength interface and substrate self-repairing that current composite material cannot realize, overcomes the technical problem that composite structure cannot be quickly repaired in situ after damage.

Description

Technical Field

[0001] This invention belongs to the field of composite material intermediate manufacturing technology, specifically relating to a method for manufacturing composite prepregs with self-healing interface and matrix capabilities, realizing a rapid and synchronous high-strength interface and matrix self-healing composite prepreg manufacturing method that is currently impossible to achieve in composite materials. Background Technology

[0002] The inherent three-dimensional cross-linked network structure of conventional thermosetting resins results in high brittleness, leading to low toughness, poor delamination resistance, and poor impact resistance in composite materials prepared using them as a matrix. Consequently, these materials often require repair and maintenance during their service life.

[0003] Polydicyclopentadiene (PDCPD) is a novel material emerging in the field of polymer materials. Studies have shown that the PDCPD repair agent system, consisting of dicyclopentadiene and a ruthenium-based catalyst, allows DCPD to undergo ring-opening metathesis polymerization with a Grubbs oxidizing agent, thus repairing cracks. Currently, most composite repair materials utilize this method to prepare microcapsules for repair. However, conventional repair methods use only a single PDCPD repair agent system, which lacks significant interfacial bonding and material diffusion with the original system, resulting in a clear process dependence on repair efficiency. Furthermore, conventional microcapsules, typically produced through injection or other conventional methods, cannot achieve sufficient in-situ repair. Summary of the Invention

[0004] The purpose of this invention is to address the problems existing in the prior art by providing a method for manufacturing composite prepregs with self-healing capabilities of the interface and matrix. This method overcomes the limitations of existing technologies with limited functionality, featuring rapid molding and rapid self-healing. Utilizing the interface repair capabilities provided by the low-content epoxy resin in the formulation, it achieves rapid, synchronous, high-strength interface and matrix self-healing, a capability currently unattainable in composite materials. This overcomes the technical problems of rapid, efficient, and high-retention-rate in-situ repair of damaged composite structural components, as well as the problem of in-situ interface repair.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] This invention provides a method for manufacturing a composite prepreg with self-healing interface and matrix capabilities, the method comprising the following steps:

[0007] (1) The self-healing microcapsule active ingredient is obtained by uniformly mixing dimercyclopentadiene and its catalyst with epoxy resin and its curing agent (added into the mixing equipment);

[0008] (2) A prepolymer solution (viscous and transparent) is obtained by initially polymerizing the aqueous solution of polymer monomers used as microcapsule shell material; a surfactant containing a certain proportion is added to the prepolymer solution; under stirring conditions, at least 1 drop of defoamer is added to the aqueous solution of polymer monomers used as microcapsule shell material, and emulsification is carried out for a certain period of time to form a stable oil-in-water (O / W) emulsion; then the pH value of the emulsion is adjusted to 3.0 to 7.0 with dilute acid, and the reaction is stopped by slowly heating and solidifying; the suspension containing microcapsules is washed, filtered and dried to obtain microcapsules;

[0009] (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; then, its viscosity and curing degree are controlled to form a dry / semi-dry resin film or a wet resin, which is then impregnated with unidirectional fiber cloth or woven fiber cloth by solvent method or hot melt method to obtain a composite material prepreg with self-healing interface and matrix. The matrix resin system is such as epoxy resin (liquid / solid), curing agent (liquid / solid) system or polyurethane (isocyanate, polyol).

[0010] As one embodiment of the present invention, in step (1), the volume percentage of dicyclopentadiene and its catalyst in the self-healing microcapsule active ingredient is 50-99.9%, with the remainder being 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 ethylene norbornene is 2-5%; in the epoxy resin and its curing agent system, a 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 by weight. Preferably, in step (1), dicyclopentadiene and its catalyst and epoxy resin and its curing agent are mixed uniformly in a mixing device at a volume ratio of 80-99.9% and 0.1-20% respectively. The system of 80-99.9% of the dicyclopentadiene and its catalyst is composed of a mixed solution of 95-98% dicyclopentadiene and 2-5% ethylene norbornene. The system of 0.1-20% of the epoxy resin and its curing agent is composed of 100 parts of epoxy resin, 10-50 parts of epoxy resin curing agent and 0-30 parts of epoxy resin accelerator by weight.

[0011] As one embodiment of the present invention, in step (2), the aqueous solution of polymer monomers is an aqueous solution of melamine resin or urea-formaldehyde resin monomers; the polymer monomers of melamine resin are melamine and formaldehyde; the polymer monomers of urea-formaldehyde resin are urea and formaldehyde.

[0012] As one embodiment of the present invention, in step (2), the reaction conditions for 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.

[0013] As one embodiment of the present invention, in step (2), the surfactant includes an oil-in-water (O / W) emulsifier.

[0014] As one embodiment of the present invention, in step (2), the amount of surfactant added is 0.1wt%-2wt% 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 dehydrated esters, polyoxyethylene ethers, polyoxyethylene fatty amines, polyethylene glycol fatty acid esters, sodium oleate, sodium rosinate, sodium dodecylbenzene sulfonate, and dialkyl sulfosuccinate.

[0015] As one embodiment of the present invention, in step (2), the defoamer includes at least one of polysiloxane (such as polydimethylsiloxane), polyvinyl alcohol (PVA), and epoxysiloxane.

[0016] As one 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.

[0017] In one embodiment of the present invention, in step (2), the dilute acid is dilute sulfuric acid or dilute hydrochloric acid.

[0018] As one embodiment of the present invention, in step (2), the heating rate of the slow heating is 0.25℃ / min-10℃ / min; the curing time is not less than 0.5 hours when the temperature is raised to 90-150℃.

[0019] Preferably, the microcapsule shell material is prepared by first polymerizing an aqueous solution of melamine resin (melamine and formaldehyde monomers) or urea-formaldehyde resin (urea and formaldehyde monomers) to obtain a viscous, transparent prepolymer aqueous solution. Then, 0.1 wt%-2 wt% of linear dodecylbenzenesulfonate or other types of surfactant are added to the melamine resin or urea-formaldehyde resin prepolymer aqueous solution. Next, under stirring conditions, the microcapsule-containing active ingredient is added to the microcapsule shell material prepolymer solution, followed by 1-2 drops of polydimethylsiloxane or other types of defoamer. Emulsification is carried out for a certain period 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 dilute hydrochloric acid, and the reaction is cured by heating at a rate of 0.25℃ / min-3℃ / min. Finally, the suspension containing the microcapsules is washed, filtered, and dried to obtain the microcapsules.

[0020] As one embodiment of the present invention, in step (2), the mass ratio of the self-healing microcapsule active ingredient to the prepolymer solution containing surfactant is 1-10:100.

[0021] As one embodiment of the present invention, in step (3), the weight percentage content of 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.

[0022] As one embodiment of the present invention, in step (3), the matrix resin system of the prepreg is one or more of the following resin systems: epoxy resin, bismaleimide resin, cyanate resin, polyurethane resin, polyimide resin, unsaturated resin, and epoxy vinyl resin.

[0023] As one embodiment of the present invention, in step (3), the fiber cloth in the prepreg is at least one of carbon fiber, glass fiber, aramid fiber, polyimide fiber, and ultra-high molecular weight polyethylene fiber, either unidirectional or blended.

[0024] In one embodiment of the present invention, in step (3), 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. Preferably, in the catalyst matching the active ingredient of the microcapsule, 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.

[0025] As one 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.

[0026] As one embodiment of the present invention, in step (3), the viscosity of the wet prepreg resin is 1000-6000 mPa•s.

[0027] Preferably, in step (3), the self-healing microcapsules obtained in step (2) and the 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 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 form of prepreg resin (wherein the viscosity of the dry or semi-dry resin film form of prepreg resin is 6000-80000 mPa•s; the viscosity of the wet form of prepreg resin is 1000-6000 mPa•s). Then, it is impregnated with unidirectional fiber cloth or woven fiber cloth by solvent method or hot melt method to manufacture a composite prepreg with self-healing ability of interface and matrix. The specific manufacturing process is as follows: Figure 2 , Figure 3 As shown. The original resin system is such as epoxy resin (liquid / solid), curing agent (liquid / solid) system or polyurethane (isocyanate, polyol).

[0028] The composite material prepreg produced by the method of this invention also falls within the scope of protection of this invention.

[0029] This invention employs dimercyclopentadiene and its catalyst system, along with epoxy resin and its curing agent system, as the active ingredients for self-healing microcapsules. These capsules are then premixed into prepolymer resins such as epoxy resin. This enables the self-healing material to automatically repair internal cracks and maintain mechanical properties under external force (damage). Combining the rapid prototyping and self-healing characteristics of PDCPD (Polydioxanone Dioxide), and utilizing the interface repair capabilities provided by the low-content epoxy resin in the formulation, this invention achieves rapid and synchronous high-strength interface and matrix self-healing, a feat currently unattainable in composite materials. It overcomes the technical problem of rapid in-situ and interface repair of damaged composite structural components. The multiple steps and technical features of this invention are interconnected and synergistic, effectively combining the strengths of all materials within the invention while mitigating their weaknesses.

[0030] It is also pointed out that this invention relates to the manufacture of prepregs and formulations in conjunction with resins and fabric reinforcements. Furthermore, this invention achieves a rapid interface repair advantage not found in existing patents. Therefore, through resin matrix formulation design, this invention achieves in-situ repair and interface repair that is currently impossible to achieve with existing technologies, combining rapid, high-efficiency, and high-retention capabilities, demonstrating originality and inventiveness.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) The present invention uses dicyclopentadiene and its catalyst system and epoxy resin and its curing agent system as self-healing microcapsule active ingredients, and then premixes the capsules in epoxy resin and other prepolymer resins to realize that the self-healing material has the function of automatically repairing and maintaining mechanical properties when cracks appear inside the composite material after damage under external force (damage).

[0033] (2) This invention overcomes the shortcomings of the single function of the prior art. By combining dicyclopentadiene and its catalyst system and epoxy resin and its curing agent system, it overcomes the shortcomings of poor interface bonding between PDCPD repair agent and conventional carbon fiber, glass fiber and other reinforcing fiber composite materials, resulting in low strength and stiffness of the composite material after repair. It realizes that the technical features of the formulation are related and synergistic, and achieves the synergistic effect of rapid molding and good interface bonding.

[0034] (3) This invention combines the rapid molding and self-healing characteristics of PDCPD itself, and at the same time uses the low content of epoxy resin in the formula to overcome the weakness of the interface bonding between PDCPD and conventional fibers and resins; it realizes the rapid and synchronous high-strength interface and matrix self-healing that cannot be achieved by current composite materials, and overcomes the technical problem that composite structural parts cannot be quickly repaired in situ after damage. Attached Figure Description

[0035] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0036] Figure 1 A schematic diagram illustrating the repair principle of a composite material sheet made of a composite prepreg with self-healing interface and matrix after damage;

[0037] Figure 2 This describes the prepreg film preparation process.

[0038] Figure 3 This describes the prepreg solution preparation process. Detailed Implementation

[0039] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims. The raw materials used in the experiments are shown in Table 1.

[0040] Table 1 Raw materials used in the experiment

[0041]

[0042] Example 1

[0043] This embodiment provides a method for manufacturing a composite prepreg with self-healing interface and matrix capabilities, comprising the following steps:

[0044] (1) Dicyclopentadiene and its catalyst system and epoxy resin and its curing agent system are mixed evenly in a mixing device at a volume ratio of 99.9% and 0.1% to obtain self-healing microcapsule active ingredients.

[0045] The dimercyclopentadiene and its catalyst system are composed of a mixed solution of 95% dimercyclopentadiene and 5% ethylidene norbornene.

[0046] The epoxy resin and its curing agent system is a monomer mixture system composed 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%).

[0047] (2) Microcapsule shell material: First, a viscous and transparent prepolymer aqueous solution is obtained by prepolymerizing the polymer monomer aqueous solution of melamine resin (melamine and formaldehyde monomers) (temperature 80℃, pH=7, polymerization for 2h), and then 0.1wt% sodium dodecylbenzenesulfonate is added to the melamine resin prepolymer aqueous solution.

[0048] Then, under stirring conditions, the active ingredient of the microcapsule (10 wt.%) was added to the prepolymer solution of the microcapsule shell material, followed by 2 drops of polydimethylsiloxane. Emulsification was then performed (emulsification temperature 25℃, emulsification speed 500 rpm, emulsification time 20 min) to form a stable oil-in-water (O / W) emulsion. The pH of the emulsion was then adjusted to 3 with dilute sulfuric acid, and the temperature was increased to 120℃ at a rate of 1℃ / min for curing for 40 min. After curing, the suspension containing the microcapsules was washed, filtered, and dried to obtain the microcapsules.

[0049] (3) The self-healing microcapsules and the catalyst matching the active ingredients of the microcapsules are mixed in the high-toughness medium-temperature curing epoxy resin JTX135 to obtain the prepreg resin (the weight percentage of the microcapsules in the prepreg resin is 5%; the weight of the catalyst is 1 / 2000 of the weight of the microcapsules); the catalyst is a catalyst solution prepared by dissolving Grubbs second-generation catalyst and tributyl phosphite in cyclohexylbenzene; finally, the viscosity of the original resin system is controlled to form a dry resin film, and then impregnated with 24K carbon fiber yarn unidirectional fabric by hot melt method to obtain a composite prepreg with self-healing ability of interface and matrix.

[0050] In the catalysts that match the active ingredients of the microcapsules, the mass ratio of Grubbs second-generation catalyst to tributyl phosphite is 1:0.05; the mass ratio of Grubbs second-generation catalyst to cyclohexylbenzene is 1:100.

[0051] (4) Based on the aforementioned prepreg, composite material flat plates were prepared by molding process (125℃, 0.6MPa, 2h).

[0052] (5) Based on the ASTM D7136 drop hammer impact test, the aforementioned damage was repaired by molding at 150℃, 0.6MPa for 5 minutes. The repair mechanism is as follows: Figure 1 As shown.

[0053] Then, samples are taken to test the retention rate of mechanical properties. Specifically, the tensile strength in the warp and weft directions is tested according to ASTM D3039. In addition, according to ASTM D7316, the impact standard test uses a constant impact energy normalized to the test thickness. The thickness of each laminate is measured, and the required impact energy is calculated according to the following formula.

[0054] E = CE·h;

[0055] In the formula, E represents the impact energy (J); CE is the ratio of standard impact energy to sample thickness, 6.7 J / mm; h is the sample thickness (mm). The magnitude of the impact energy is calibrated by adjusting the drop height of the hammer. The drop height is calculated using the following formula:

[0056] H=E / (m d ·g);

[0057] In the formula, H is the drop height (m), m d Here, g is the mass of the falling weight (kg), and g is the acceleration due to gravity, typically 9.8 m / s². 2 .

[0058] 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.

[0059] ;

[0060] In the formula, Represents the ultimate compressive remaining strength (MPa). Represents the maximum force (N) before failure, and A represents the cross-sectional area under compression (mm²). 2 ).

[0061] Example 2

[0062] This embodiment relates to a method for manufacturing a composite prepreg with self-healing interface and matrix capabilities, comprising the following steps:

[0063] (1) Dicyclopentadiene and its catalyst system and epoxy resin and its curing agent system are mixed evenly in a mixing device at a volume ratio of 80% and 20% to obtain self-healing microcapsule active ingredients.

[0064] The dimercyclopentadiene and its catalyst system consist of a mixed solution of 98% dimercyclopentadiene and 2% ethylidene norbornene.

[0065] The epoxy resin and its curing agent system is a monomer mixture system composed 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%).

[0066] (2) Microcapsule shell material is obtained by first polymerizing the polymer monomer aqueous solution of urea-formaldehyde resin (polymerization of urea and formaldehyde monomers) (temperature 80℃, pH=7, polymerization for 2h) to obtain a viscous and transparent prepolymer aqueous solution, and then adding 2 wt% polyoxyethylene ether oil-in-water (O / W) emulsifier to the urea-formaldehyde resin prepolymer aqueous solution.

[0067] Then, under stirring conditions, 5 wt.% of the active ingredient of the microcapsule was added to the prepolymer solution of the microcapsule shell material, along with 1 drop of polydimethylsiloxane defoamer. Emulsification was carried out for a certain time (emulsification temperature 25℃, emulsification speed 500 rpm, emulsification time 30 min) to form a stable oil-in-water (O / W) emulsion. The pH of the emulsion was then adjusted to 4 with dilute sulfuric acid or dilute hydrochloric acid, and the temperature was increased to 120℃ at a rate of 3℃ / min for 60 min to solidify. The reaction was then terminated. Finally, the suspension containing the microcapsules was washed, filtered, and dried to obtain the microcapsules.

[0068] (3) The self-healing microcapsules and the catalyst matching the active ingredients of the microcapsules are mixed in high-toughness medium-temperature curing epoxy resin JTX135 to obtain a prepreg resin (the weight percentage of the microcapsules in the prepreg resin is 5%; the weight of the catalyst is 1 / 2000 of the weight of the microcapsules); the catalyst is 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 are controlled to form a dry prepreg resin film, and then impregnated with 24K carbon fiber yarn unidirectional fabric by hot melt method to obtain a composite prepreg with self-healing ability of interface and matrix.

[0069] Among the catalysts that match the active ingredients of the microcapsules, the mass ratio of Grubbs second-generation catalyst to cyclohexylbenzene is 1:400; the mass ratio of second-generation catalyst to tributyl phosphite is 1:0.1.

[0070] (4) Based on the aforementioned prepreg, composite material flat plates were prepared by molding process (125℃, 0.6MPa, 2h).

[0071] (5) Based on the ASTM D7136 drop hammer impact test, the aforementioned damage was repaired by molding at 150℃, 0.6MPa for 10min. The repair mechanism is as follows: Figure 1 As shown.

[0072] Then, samples are taken to test the retention rate of mechanical properties. Specifically, the tensile strength in the warp and weft directions is tested according to ASTM D3039. In addition, according to ASTM D7316, the impact standard test uses a constant impact energy normalized to the test thickness. The thickness of each laminate is measured, and the required impact energy is calculated according to the following formula.

[0073] E = CE·h;

[0074] In the formula, E represents the impact energy (J); CE is the ratio of standard impact energy to sample thickness, 6.7 J / mm; h is the sample thickness (mm). The magnitude of the impact energy is calibrated by adjusting the drop height of the hammer. The drop height is calculated using the following formula:

[0075] H=E / (m d ·g);

[0076] In the formula, H is the drop height (m), m d Here, g is the mass of the falling weight (kg), and g is the acceleration due to gravity, typically 9.8 m / s². 2 .

[0077] 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.

[0078] ;

[0079] In the formula, Represents the ultimate compressive remaining strength (MPa). Represents the maximum force (N) before failure, and A represents the cross-sectional area under compression (mm²). 2 ).

[0080] Comparative Example 1

[0081] Damaged composite materials prepared from carbon fiber reinforced epoxy resin prepreg (SCF40S-L5-24K / JXT135-133-34%-1000mm) were not repaired; samples were taken directly, and their performance was tested according to the following methods.

[0082] Specifically, tensile strength in the warp and weft directions is tested according to ASTM D3039. Additionally, according to ASTM D7316, the impact standard test uses a constant impact energy normalized to the test thickness. The thickness of each laminate is measured, and the required impact energy is calculated using the following formula.

[0083] E = CE·h;

[0084] In the formula, E represents the impact energy (J); CE is the ratio of standard impact energy to sample thickness, 6.7 J / mm; h is the sample thickness (mm). The magnitude of the impact energy is calibrated by adjusting the drop height of the hammer. The drop height is calculated using the following formula:

[0085] H=E / (m d ·g);

[0086] In the formula, H is the drop height (m), m d Here, g is the mass of the falling weight (kg), and g is the acceleration due to gravity, typically 9.8 m / s². 2 .

[0087] 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.

[0088] ;

[0089] In the formula, Represents the ultimate compressive remaining strength (MPa). Represents the maximum force (N) before failure, and A represents the cross-sectional area under compression (mm²). 2 ).

[0090] Comparative Example 2

[0091] The main difference between this comparative example and the embodiment is that it uses melamine-formaldehyde resin (MF resin) as the shell material and dicyclopentadiene (DCPD) as the core material, as reported in the literature, to prepare microcapsules for self-healing materials through in-situ polymerization.

[0092] (1) The specific synthesis of the microcapsules is as follows: 270g of melamine-formaldehyde prepolymer, 60g of acrylic acid / acrylamide copolymer, and 1400g of deionized water were placed in a cylindrical reactor and dissolved by stirring with a turbulent impeller. Acetic acid was used to adjust the pH of the solution to 4.0. Then, 65g of the core material dicyclopentadiene was added to the system, and emulsification was carried out using an emulsifier at a certain speed and room temperature for 140min. The water bath temperature was then raised to 65℃, and turbulent impeller was used to stir at a speed of 400rpm. After the reaction continued for a period of time, the pH of the dispersion system was adjusted to 10 using a 20% NaOH solution. The product was discharged and washed with deionized water.

[0093] (2) The self-healing microcapsules and the catalyst matching the active ingredients of the microcapsules are 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 is 5%; the weight of the catalyst is 1 / 2000 of the weight of the microcapsules); the catalyst is 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 are controlled to form a dry prepreg resin film, and then the composite material prepreg is obtained by impregnation with 24K carbon fiber yarn unidirectional fabric by hot melt method.

[0094] Among the catalysts that match the active ingredients of the microcapsules, the mass ratio of Grubbs second-generation catalyst to cyclohexylbenzene is 1:400; the mass ratio of second-generation catalyst to tributyl phosphite is 1:0.1.

[0095] (3) Based on the aforementioned prepreg, composite material flat plates were prepared by molding process (125℃, 0.6MPa, 2h).

[0096] (4) Based on the ASTM D7136 drop hammer impact test, the aforementioned damage was repaired by molding at 150℃, 0.6MPa for 5 minutes. Then, samples were taken to test the retention rate of mechanical properties. Specifically, the tensile strength in the warp and weft directions was tested according to ASTM D3039. Additionally, according to ASTM D7316, the impact standard test uses a constant impact energy normalized to the test thickness. The thickness of each laminate was measured, and the required impact energy was calculated using the following formula.

[0097] E = CE·h;

[0098] In the formula, E represents the impact energy (J); CE is the ratio of standard impact energy to sample thickness, 6.7 J / mm; h is the sample thickness (mm). The magnitude of the impact energy is calibrated by adjusting the drop height of the hammer. The drop height is calculated using the following formula:

[0099] H=E / (md ·g);

[0100] In the formula, H is the drop height (m), m d Here, g is the mass of the falling weight (kg), and g is the acceleration due to gravity, typically 9.8 m / s². 2 .

[0101] 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.

[0102] ;

[0103] In the formula, Represents the ultimate compressive remaining strength (MPa). Represents the maximum force (N) before failure, and A represents the cross-sectional area under compression (mm²). 2 ).

[0104] Comparative Example 3

[0105] This comparative example is the same as comparative example 2, using the method reported in the literature, which uses melamine-formaldehyde resin (melamine resin MF) as the shell material and dicyclopentadiene (DCPD) as the core material to prepare microcapsules for self-healing materials via in-situ polymerization.

[0106] (1) The specific synthesis of the microcapsules is as follows: 270g of melamine-formaldehyde prepolymer, 60g of acrylic acid / acrylamide copolymer and 1400g of deionized water were placed in a cylindrical reactor and dissolved by stirring with a turbulent impeller. Acetic acid was used to adjust the pH of the solution to 4.0. Then, 65g of the core material dicyclopentadiene was added to the system and emulsified using an emulsifier. Emulsification was carried out continuously for 140min at a certain speed and room temperature. The water bath temperature was then raised to 65℃ and stirred with a turbulent impeller at a speed of 400rpm. After the reaction continued for a period of time, the pH of the dispersion system was adjusted to 10 using a 20% (w / w) NaOH solution. The product was discharged and washed with deionized water.

[0107] (2) The self-healing microcapsules and the catalyst matching the active ingredients of the microcapsules are mixed in high-toughness medium-temperature curing epoxy resin JTX135 to obtain a prepreg resin (the weight percentage of the microcapsules in the prepreg resin is 5%; the weight of the catalyst is 1 / 2000 of the weight of the microcapsules); the catalyst is a catalyst solution prepared by dissolving Grubbs second-generation catalyst and tributyl phosphite in cyclohexylbenzene and simultaneously adding epoxy resin and its curing agent system; finally, the viscosity and curing degree of the original resin system are controlled to form a dry prepreg resin adhesive; the film is then impregnated with 24K carbon fiber yarn unidirectional fabric by hot melt method to produce composite prepreg.

[0108] The epoxy resin and curing agent system is a monomer mixture system composed 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 curing agent system to the self-healing microcapsule core material dicyclopentadiene is 1:4.

[0109] In the catalysts that match the active ingredients of the microcapsules, 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.

[0110] (3) Based on the aforementioned prepreg, composite material flat plates were prepared by molding process (125℃, 0.6MPa, 2h).

[0111] (4) The aforementioned damage was repaired based on the ASTM D7136 drop hammer impact test, followed by molding at 150°C, 0.6 MPa for 150 min. Samples were then taken to test the retention rate of mechanical properties. Specifically, the tensile strength in the warp and weft directions was tested according to ASTM D3039. Additionally, according to ASTM D7316, the impact standard test uses a constant impact energy normalized to the test thickness. The thickness of each laminate was measured, and the required impact energy was calculated using the following formula.

[0112] Repair was carried out using the aforementioned prepreg based on the HB / Z 410-2013 standard for repairing resin-based composite parts.

[0113] The sampling was performed to test the performance using the following method.

[0114] Specifically, tensile strength in the warp and weft directions is tested according to ASTM D3039. Additionally, according to ASTM D7316, the impact standard test uses a constant impact energy normalized to the test thickness. The thickness of each laminate is measured, and the required impact energy is calculated using the following formula.

[0115] E = CE·h;

[0116] In the formula, E represents the impact energy (J); CE is the ratio of standard impact energy to sample thickness, 6.7 J / mm; h is the sample thickness (mm). The magnitude of the impact energy is calibrated by adjusting the drop height of the hammer. The drop height is calculated using the following formula:

[0117] H=E / (m d ·g);

[0118] In the formula, H is the drop height (m), m d Here, g is the mass of the falling weight (kg), and g is the acceleration due to gravity, typically 9.8 m / s². 2 .

[0119] 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.

[0120] ;

[0121] In the formula, Represents the ultimate compressive remaining strength (MPa). Represents the maximum force (N) before failure, and A represents the cross-sectional area under compression (mm²). 2 ).

[0122] The data measured in the above embodiments and comparative examples are shown in Table 2.

[0123] Table 2. Material Performance Comparison Table

[0124]

[0125] In summary, the composite prepreg of this invention uses thermosetting resin prepolymers such as epoxy resin, polyurethane, unsaturated resin, epoxy vinyl ester, and bismaleimide resin as prepreg resin materials; fiber reinforcing materials such as carbon fiber and glass fiber as fiber materials; melamine (melamine-formaldehyde) resin (MF) and urea-formaldehyde (urea-formaldehyde) resin (UF) as capsule shell materials; and dicyclopentadiene and its catalyst system and epoxy resin and its curing agent system as self-healing microcapsule active ingredients. The capsules are then premixed in epoxy resin and other prepreg resins, enabling the self-healing material to automatically repair and maintain its mechanical properties when internal cracks appear after damage under external force (damage). The self-healing microcapsule active ingredients are composed of 80-99.9% dicyclopentadiene system and 0.1-20% epoxy resin system by volume. This invention combines the rapid prototyping and self-healing characteristics of PDCPD with the interface repair capabilities provided by the low content of epoxy resin in the formulation, to achieve rapid and synchronous high-strength interface and matrix self-healing that is currently impossible for composite materials. This overcomes the technical problem that composite structural parts cannot be quickly repaired in situ after damage.

[0126] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A method for manufacturing a composite prepreg with self-healing interface and matrix capabilities, characterized in that, The method includes the following steps: (1) A self-healing microcapsule active ingredient is obtained by uniformly mixing dicyclopentadiene and its catalyst with epoxy resin and its curing agent; the volume percentage of dicyclopentadiene and its catalyst in the self-healing microcapsule active ingredient is 50-99.9%, and the remainder 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 ethylene norbornene is 2-5%; (2) The polymer monomer aqueous solution used as the microcapsule shell material is initially polymerized to obtain a prepolymer solution; a certain proportion of surfactant is added to the prepolymer solution; the self-healing microcapsule active ingredient is added to the prepolymer solution containing surfactant under stirring conditions, and at least 1 drop of defoamer is added, and emulsification is carried out for a certain time to form a stable oil-in-water emulsion; then the pH value of the emulsion is adjusted to 3.0-7.0 with dilute acid, and the reaction is stopped by slow heating and solidification; the suspension containing microcapsules is washed, filtered and dried to obtain microcapsules; (3) The microcapsules and the catalyst matching the active ingredients of the microcapsules are mixed in the matrix resin system to obtain a prepreg resin; the viscosity and curing degree are controlled to form a dry / semi-dry resin film or a wet resin, and then impregnated with unidirectional fiber cloth or woven fiber cloth by hot melt method or solvent method to obtain a composite material prepreg with interface and matrix self-healing ability.

2. The method for manufacturing composite prepreg according to claim 1, characterized in that, In step (1), The epoxy resin and its curing agent system consists of a mixture of 100 parts epoxy resin, 10-50 parts epoxy resin curing agent, and 0-30 parts epoxy resin accelerator by weight.

3. The method for manufacturing composite prepreg according to claim 1, characterized in that, Step (2) also includes at least one of the following technical features: A1. The aqueous solution of the polymer monomer is an aqueous solution of melamine resin or urea-formaldehyde resin monomer; the polymer monomer of the melamine resin is melamine and formaldehyde; the polymer monomer of the urea-formaldehyde resin is urea and formaldehyde. A2. The reaction conditions for the preliminary polymerization are: temperature not exceeding 85℃, pH value between 7.0 and 11.0, and reaction time not less than 2 hours; A3. The surfactant includes an oil-in-water emulsifier; A4. The amount of surfactant added is 0.1wt%-2wt% based on the weight percentage of the total weight of the prepolymer solution and surfactant; the surfactant is selected from at least one of polyoxyethylene dehydrated esters, polyoxyethylene ethers, polyoxyethylene fatty amines, polyethylene glycol fatty acid esters, sodium oleate, sodium rosinate, sodium dodecylbenzene sulfonate, and dialkyl sulfosuccinate. A5. The defoamer includes at least one of polysiloxane, polyvinyl alcohol, and epoxysiloxane; A6. The emulsification temperature shall be not less than 10℃ and not more than 85℃, the emulsification speed shall be 100-6000 rpm, and the emulsification time shall be 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℃ / min-10℃ / min; the curing time at 90-150℃ is not less than 0.5 hours.

4. The method for manufacturing composite prepreg according to claim 1, characterized in that, In step (2), the mass ratio of the self-healing microcapsule active ingredient to the prepolymer solution containing surfactant is 1-10:

100.

5. The method for manufacturing composite prepreg according to claim 1, characterized in that, In step (3), the prepreg resin contains 0.5-10% by weight of microcapsules; the catalyst matching the active ingredients of the microcapsules has a weight of 1 / 1000-1 / 40000 of the microcapsule weight.

6. The method for manufacturing composite prepreg according to claim 1, characterized in that, 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 the following resin systems: 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 blended woven fabric of at least one of carbon fiber, glass fiber, aramid fiber, polyimide fiber, and ultra-high 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 viscosity of the prepreg resin for dry / semi-dry resin films is 6000-80000 mPa•s; B5. The viscosity of the wet-state prepreg resin is 1000-6000 mPa•s.

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

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

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