High-efficiency composite material manufacturing method based on front-end polymerization initiation point design

Abstract

The invention provides an efficient composite material manufacturing method based on front-end polymerization initiation point design, relates to manufacturing of forming materials containing macromolecular substances, and belongs to the technical field of common technological processes of processing and batching of macromolecular materials. According to the invention, the epoxy resin composite material with excellent mechanical properties is rapidly prepared with low energy consumption by preparing the epoxy resin front-end polymerization solution and initiating front-end polymerization at multiple points. The method has the advantages of being high in designability, easy to operate and the like, and rapid and energy-saving manufacturing of the epoxy resin and the composite material thereof is achieved while the mechanical property is maintained through multi-point initiation of front-end polymerization. The method has a wide application prospect in batch production of epoxy resin and composite materials and manufacturing of large-scale structures.

Description

Technical Field

[0001] The present invention belongs to the technical field of general process of processing and batching of polymer materials, and relates to the manufacture of shaped materials containing polymer substances. Specifically, it relates to a method for efficiently manufacturing composite materials based on the design of front-end polymerization initiation points. Background Art

[0002] Epoxy resin is the most widely used matrix material in composite materials and is widely applied in different fields such as the aviation industry, marine, automotive, and sporting goods. Epoxy resin-based composite materials usually need to add amines or acid anhydrides as curing agents and are formed by high-temperature curing for several hours or even several days. Traditional thermoforming methods consume a large amount of energy, emit high levels of waste gases such as carbon dioxide, require large curing equipment, and cannot be cured in-situ. Therefore, in order to achieve efficient energy conservation and batch rapid curing of epoxy resin and its composite materials, it is urgent to find a new forming method. Front-end polymerization (FP) is a method that relies on the exothermicity of the polymerization reaction. After being stimulated by light or heat, a local reaction zone is formed, and this reaction zone will initiate further reactions in the adjacent areas, and the curing and forming of epoxy resin and its composite materials can be completed within a few minutes.

[0003] When it comes to manufacturing, especially for large-scale production and the production of large components such as wind turbine blades, improving the efficiency of the curing process is the key to reducing production costs. Existing research has improved the curing efficiency by increasing the initiator concentration and the initial temperature of the resin. Chinese Patent CN108431075B prepared epoxy resin through front-end polymerization, and this technology promoted the propagation of the reaction front by increasing the initiator concentration. However, a high initiator concentration may cause pores to be generated during the front-end polymerization process, resulting in a significant decline in product quality. In addition, Goli et al. disclosed front-end polymerization based on dicyclopentadiene resin in Compos. Part B - Eng. 199, 108306 (2020) and found that as the initial temperature of the resin increased, the front-end speed increased. However, a high front-end temperature is extremely likely to cause bulk polymerization of the resin. Therefore, simply increasing the curing efficiency by increasing the initiator concentration and the initial temperature of the resin has certain limitations. Summary of the Invention

[0004] The present invention is made to solve the above problems, and the purpose is to provide a method for efficiently manufacturing composite materials based on the design of front-end polymerization initiation points.

[0005] The present invention provides an efficient manufacturing method for composite materials based on the design of front-end polymerization initiation points, having the following characteristics, including the following steps: S10, preparing a first mixed solution of epoxy resin, diluent, photoinitiator, and thermal initiator, wherein the molar percentage concentration of the photoinitiator in the first mixed solution is 0.5 mol% to 5.5 mol%, the molar percentage concentration of the thermal initiator in the first mixed solution is 0.5 mol% to 5.5 mol%, the molar ratio of the diluent to the epoxy resin is (2 to 3):(7 to 8), the photoinitiator is 4-(octyloxyphenyl)phenyl iodonium hexafluoroantimonate and / or tetraalkyl(perfluorotert-butoxy)aluminate anion, the thermal initiator is benzoin, and the epoxy resin is bisphenol A diglycidyl ether; A20, adding discrete fillers to the first mixed solution and mixing evenly to obtain a second mixed solution, the discrete fillers being reinforcing and functional fillers, and the mass fraction of the discrete fillers in the second mixed solution being 0.5 wt% to 35 wt%; A30, heating the second mixed solution to a preset initial temperature of 30 °C to 70 °C to obtain a first epoxy resin front-end polymerization solution; A40, after pouring the first epoxy resin front-end polymerization solution into a mold, designing the number and position arrangement of the initiation points based on the polymerization front propagation speed according to the requirements of actual production for the curing time and energy consumption; A50, initiating front-end polymerization at the positions of the initiation points by means of ultraviolet light irradiation or local heating, and after the front-end is initiated, removing the ultraviolet light or the heating point, and the polymerization front self-propagates by the heat released from the polymerization reaction. The first epoxy resin front-end polymerization solution rapidly cures at a spreading rate of not less than 2.5 cm / min from the initiation points and the degree of cure is greater than 95%, and finally a completely cured epoxy resin is obtained.

[0006] The present invention provides an efficient manufacturing method for composite materials based on the design of front-end polymerization initiation points, which has the following characteristics. It includes the following steps: S10, preparing a first mixed solution of epoxy resin, diluent, photoinitiator, and thermal initiator. Among them, the molar percentage concentration of the photoinitiator in the first mixed solution is 0.5 mol% - 5.5 mol%, the molar percentage concentration of the thermal initiator in the first mixed solution is 0.5 mol% - 5.5 mol%, the molar ratio of the diluent to the epoxy resin is (2 - 3):(7 - 8), the photoinitiator is 4-(octyloxyphenyl)phenyl iodonium hexafluoroantimonate and / or tetraalkyl(perfluorotert-butoxy)aluminate anion, the thermal initiator is benzoin pinacol, and the epoxy resin is bisphenol A diglycidyl ether; B20, heating the first mixed solution to a preset initial temperature of 30 °C - 70 °C to obtain a second epoxy resin front-end polymerization solution; B30, laying continuous fiber fillers in a mold. The continuous fiber fillers are continuous fiber fabrics, and the mass ratio of the continuous fiber fillers to the second epoxy resin front-end polymerization solution is 5:95 - 35:65; B40, after pouring the second epoxy resin front-end polymerization solution into the mold, based on the requirements of actual production for curing time and energy consumption, designing the number and position arrangement of initiation points according to the propagation speed of the polymerization front; B50, initiating front-end polymerization at the positions of the initiation points by ultraviolet light irradiation or local heating. After the front-end is initiated, removing the ultraviolet light or the heating point. The polymerization front propagates self-exothermically by the polymerization reaction. The second epoxy resin front-end polymerization solution rapidly cures at a spreading rate of not less than 2.7 cm / min from the initiation points and the degree of curing is greater than 95%, and finally a fully cured epoxy resin-based composite material is obtained.

[0007] In the efficient manufacturing method for composite materials based on the design of front-end polymerization initiation points provided by the present invention, it may also have the following characteristics: Among them, step S10 includes the following sub-steps: S11, putting the photoinitiator and the thermal initiator into an organic solvent and stirring at high speed until dissolved to obtain an initiator solution; S12, putting the epoxy resin and the diluent into the initiator solution, mixing evenly, and then discharging the organic solvent to obtain the first mixed solution.

[0008] In the efficient manufacturing method for composite materials based on the design of front-end polymerization initiation points provided by the present invention, it may also have the following characteristics: Among them, in step S11, the organic solvent includes dichloromethane and / or ethyl acetate.

[0009] In the efficient manufacturing method for composite materials based on the design of front-end polymerization initiation points provided by the present invention, it may also have the following characteristics: Among them, in step S10, the diluent includes any one or more of 3-ethyl-3-oxetane methanol, glycidyl neopentyl glycol diglycidyl ether, hexanediol diglycidyl ether, cyclohexanedimethanol, and cyclohexyl epoxy ester.

[0010] In the method for efficiently manufacturing a composite material based on the design of a front-end polymerization initiation point provided by the present invention, it may further have the following characteristics: Among them, in step S10, the molar ratio of the photoinitiator to the thermal initiator is 1:0.5 to 1:2.

[0011] In the method for efficiently manufacturing a composite material based on the design of a front-end polymerization initiation point provided by the present invention, it may further have the following characteristics: Among them, in step A30 or step B20, the heating operation is achieved by an oven, a heating pad or a heating table.

[0012] In the method for efficiently manufacturing a composite material based on the design of a front-end polymerization initiation point provided by the present invention, it may further have the following characteristics: Among them, in step A30 or step B40, the first epoxy resin front-end polymerization solution or the second epoxy resin front-end polymerization solution is also subjected to vacuum degassing treatment.

[0013] In the method for efficiently manufacturing a composite material based on the design of a front-end polymerization initiation point provided by the present invention, it may further have the following characteristics: Among them, in step A40 or step B40, the number of initiation points is the ratio of the total value of the energy consumption to the energy consumption of a single initiation point. When the actual production requirements are the lowest for both energy consumption and curing time, the curing area of the first epoxy resin front-end polymerization solution or the second epoxy resin front-end polymerization solution in the mold is approximated as a rectangular area of length multiplied by width. All polymerization fronts start from the initiation points. The area to be cured is divided into squares with equal side lengths along the length and width respectively, and polymerization fronts are initiated simultaneously at the center positions of the squares.

[0014] In the method for efficiently manufacturing a composite material based on the design of a front-end polymerization initiation point provided by the present invention, it may further have the following characteristics: Among them, in step A50 or step B50, when the method for initiating front-end polymerization is ultraviolet light irradiation, the wavelength of the ultraviolet light source is 365 nm, and the irradiation time is 15 s to 20 s. When the method for initiating front-end polymerization is local heating, the implementation methods of local heating include soldering iron heating or laser heating.

[0015] A method for efficiently manufacturing a composite material based on the design of a front-end polymerization initiation point of the present invention has the following beneficial effects: (1) The resin formulation design of the mixture in step S10 of the present invention can effectively avoid the formation of cured gas products and resin pyrolysis during the front-end polymerization process, avoid the formation of pores in the merged area, and maintain the mechanical properties of the material.

[0016] (2) The selected ultraviolet light irradiation initiation method in steps A40 to A50 or steps B40 to B50 of the present invention can adjust the irradiation position as needed according to the product structure, which is convenient for increasing and decreasing the number of initiation points and the layout design.

[0017] (3) The multi-point initiation front polymerization molding method selected in steps A40 to A50 or steps B40 to B50 of the present invention can shorten the molding cycle of several hours or even longer to a few minutes, while avoiding long-term high-temperature treatment, and reducing the energy consumption by about 8 orders of magnitude.

[0018] (3) Since the present invention selects self-propagating front polymerization relying on the exotherm of the polymerization reaction, once the polymerization front is initiated, no further energy input is required. By designing the number and position of the initiation points, multiple polymerization fronts diffuse simultaneously, realizing the rapid and energy-saving molding and manufacturing of epoxy resins and their composites.

[0019] (4) The front polymerization selected in the present invention has a high heat release amount and rapid heat release property, which can achieve complete curing. At the same time, the high front merging temperature enhances the crosslinking density of the epoxy resin, thereby significantly improving the mechanical properties of the sample.

[0020] (5) The high-efficiency manufacturing method of composites based on the design of front polymerization initiation points of the present invention is simple to operate and flexible in design. The number and arrangement of initiation points can be selected as needed, taking into account both the curing efficiency and mechanical properties. It is a rapid, efficient and energy-saving high-performance epoxy resin and its composite manufacturing method, and has broad application prospects in the batch production of epoxy resins and composites and the manufacturing of large structural parts. Description of the Drawings

[0021] Figure 1 is a flowchart of a high-efficiency manufacturing method of composites based on the design of front polymerization initiation points in Example 1 of the present invention.

[0022] Figure 2 is a schematic diagram of the initiation point arrangement design in Example 1 of the present invention.

[0023] Figure 3 is a schematic diagram of the initiation point arrangement design in Example 2 of the present invention.

[0024] Figure 4 is a flowchart of a high-efficiency manufacturing method of composites based on the design of front polymerization initiation points in Example 3 of the present invention.

[0025] Figure 5 is a schematic diagram of the initiation point arrangement design in Example 3 of the present invention.

[0026] Figure 6 is an SEM image of Comparative Sample 1 in the test example of the present invention.

[0027] Figure 7 is a comparison of the flexural properties of Comparative Sample 1 and Comparative Sample 2 in the test example of the present invention.

[0028] Figure 8It is a comparison of the bending properties between Sample 3 of the test example of the present invention and Comparative Sample 3. Detailed implementation mode

[0029] In order to make the technical means, creative features, achieved purposes and effects realized by the present invention easy to understand, the following embodiments will specifically elaborate on a high-efficiency manufacturing method of a composite material based on the design of a front-end polymerization initiation point of the present invention in conjunction with the accompanying drawings.

[0030] Embodiment 1 Figure 1 It is a flow block diagram of a high-efficiency manufacturing method of a composite material based on the design of a front-end polymerization initiation point in Embodiment 1 of the present invention.

[0031] As Figure 1 shown, this embodiment provides a high-efficiency manufacturing method of a composite material based on the design of a front-end polymerization initiation point, including the following steps: S10, configure a first mixed solution of epoxy resin, diluent, photoinitiator and thermal initiator, including the following sub-steps S11~S12: S11, put the photoinitiator and thermal initiator into an organic solvent and stir at high speed until dissolved to obtain an initiator solution.

[0032] The photoinitiator is 4-(octyloxyphenyl)phenyl iodonium hexafluoroantimonate (I-Sb) and / or tetraalkyl(perfluorotert-butoxy)aluminate anion (I-Al). Specifically in this embodiment, the photoinitiator is I-Sb.

[0033] The thermal initiator is benzoin pinacol (TPED).

[0034] The organic solvent includes dichloromethane and / or ethyl acetate. Specifically in this embodiment, the organic solvent is dichloromethane.

[0035] S12, put the epoxy resin and diluent into the initiator solution, mix evenly and then discharge the organic solvent to obtain the first mixed solution.

[0036] The epoxy resin is bisphenol A diglycidyl ether (BADGE).

[0037] The diluent includes any one or more of 3-ethyl-3-oxetanemethanol (EOM), neopentyl glycol diglycidyl ester (NPDGE), hexanediol diglycidyl ester (HDDGE), cyclohexanedimethanol (CHDGE) and cyclohexyl epoxy ester (CE). Specifically in this embodiment, the diluent is EOM.

[0038] In the above steps S11 to S12, the molar percentage concentrations of the photoinitiator I-Sb and the thermal initiator TPED in the finally prepared first mixed solution of I-Sb / TPED / EOM / BADGE are both 0.5 mol% to 5.5 mol%, and the molar ratio of the photoinitiator I-Sb to the thermal initiator TPED in the feed is 1:0.5 to 1:2. The molar ratio of the diluent EOM to the epoxy resin BADGE is controlled to be (2 to 3):(7 to 8).

[0039] Specifically in this embodiment, the parameters are selected as follows: the molar ratio of the photoinitiator I-Sb to the thermal initiator TPED in the feed is controlled to be 1:1, the molar percentage concentrations of the photoinitiator I-Sb and the thermal initiator TPED in the finally prepared first mixed solution of I-Sb / TPED / EOM / BADGE are both 1 mol%, and the molar ratio of the diluent EOM to the epoxy resin BADGE is controlled to be 2:8.

[0040] A20. Add discrete fillers to the first mixed solution and mix well to obtain a second mixed solution.

[0041] Among them, the discrete fillers are reinforcing and functional fillers, and the reinforcing and functional fillers include any one or more of chopped glass fibers, carbon nanotubes, graphite, and conductive metal fillers. In the system after the discrete fillers are added to the mixed solution, the mass fraction of the discrete fillers is 0.5 wt% to 35 wt%.

[0042] Specifically in this embodiment, carbon nanotubes are selected as the discrete fillers. In the system after the discrete fillers are added to the mixed solution, the molar percentage concentration of the discrete fillers is 3 mol%.

[0043] The method of mixing the discrete fillers into the mixed solution is: magnetically stir at 50 °C for 10 min to uniformly disperse the entire system.

[0044] A30. Heat the second mixed solution to a preset initial temperature of 30 °C to 70 °C to obtain a first epoxy resin front-end polymerization solution.

[0045] Among them, the heating operation is realized by an oven, a heating pad or a heating table.

[0046] Specifically in this embodiment, the preset initial temperature is selected as 50 °C, the heating operation is realized by a vacuum oven, and the first epoxy resin front-end polymerization solution can be degassed while heating and keeping warm.

[0047] A40. After pouring the first epoxy resin front-end polymerization solution into a mold, according to the actual production requirements for the curing time and energy consumption, design the number and position arrangement of the initiation points based on the polymerization front propagation speed.

[0048] Among them, the number of initiation points is the ratio of the total energy consumption to the energy consumption of a single initiation point. When the actual production requires the lowest energy consumption and curing time, the curing area of the first epoxy resin front polymerization solution in the mold is approximated as a rectangular area of length multiplied by width. All polymerization fronts start from the initiation points. The area to be cured is divided into squares with equal side lengths along the length and width respectively, and polymerization fronts are initiated simultaneously at the center positions of the squares.

[0049] Specifically in this embodiment, it is required to satisfy that the energy consumption is lower than 2500 J and the curing time is less than 15 s. The power of each initiation point is 45 W, so the number of initiation points is set to 3. Figure 2 It is a schematic diagram of the initiation point arrangement design of Embodiment 1 of the present invention. The initiation point arrangement design in this step is as Figure 2 shown. There are a total of 3 initiation points. The 3 initiation points are arranged in an isosceles triangle-shaped connection.

[0050] A50, initiate the front-end polymerization, and the exothermic self-propagation and curing occur.

[0051] Among them, through the way of ultraviolet light irradiation or local heating, the front-end polymerization is initiated at the position of the initiation point. After the front-end is initiated, the ultraviolet light or the heating point is removed. The polymerization front propagates by the heat released from the polymerization reaction. The first epoxy resin front polymerization solution cures rapidly from the initiation point at a propagation rate of not less than 2.5 cm / min and the degree of cure is greater than 95%, and finally a fully cured epoxy resin is obtained. When the way of initiating the front-end polymerization is ultraviolet light irradiation, the wavelength of the ultraviolet light source is 365 nm, and the irradiation time is 15 s - 20 s; when the way of initiating the front-end polymerization is local heating, the implementation methods of local heating include soldering iron heating or laser heating.

[0052] Specifically in this embodiment, the way of initiating the front-end polymerization is to use three ultraviolet light sources with a wavelength of 365 nm to irradiate the epoxy resin simultaneously for 15 s at the three initiation points determined in step A40 to initiate multi-point front-end polymerization. After the front-end is initiated, the ultraviolet light source is removed, and the polymerization front gradually diffuses outward from the initiation point until the resin is completely cured.

[0053] Embodiment 2 This embodiment provides a high-efficiency manufacturing method for composites based on the design of front-end polymerization initiation points, including steps S10, A20, A30, A40, and A50.

[0054] Step S10 in this embodiment is generally similar to that in Embodiment 1 and will not be repeated. The only difference is that: in step S10 of this embodiment, the molar percentage concentrations of the photoinitiator I-Sb and the thermal initiator TPED in the first mixed solution of I-Sb / TPED / EOM / BADGE finally prepared are both 1.2 mol%.

[0055] Step A20 in this embodiment is generally similar to that in Embodiment 1 and will not be repeated. The only difference is that the discrete filler in Step A20 in this embodiment is short-cut glass fiber.

[0056] Step A30 in this embodiment is generally similar to that in Embodiment 1 and will not be repeated.

[0057] Step A40 in this embodiment: After pouring the first epoxy resin front polymerization solution into the mold, according to the requirements of actual production for curing time and energy consumption, the number and position arrangement of initiation points are designed based on the propagation speed of the polymerization front.

[0058] Among them, the number of initiation points is the ratio of the total value of energy consumption to the energy consumption of a single initiation point. When the actual production requires both the lowest energy consumption and curing time, the curing area of the first epoxy resin front polymerization solution in the mold is approximated as a rectangular area of length multiplied by width. All polymerization fronts start from the initiation points. The area to be cured is divided into squares with equal side lengths along the length and width respectively, and the polymerization fronts are initiated simultaneously at the center positions of the squares.

[0059] Specifically in this embodiment, it is necessary to meet both the lowest energy consumption and curing time. Figure 3 It is a schematic diagram of the initiation point arrangement design of Embodiment 2 of the present invention. The initiation point arrangement design of this embodiment is as Figure 3 shown, a total of 6, evenly distributed on the plane where the first epoxy resin front polymerization solution is located.

[0060] Step A50 in this embodiment is generally similar to that in Embodiment 1 and will not be repeated.

[0061] Embodiment 3 Figure 4 It is a flowchart of a high-efficiency manufacturing method of a composite material based on the design of front polymerization initiation points in Embodiment 3 of the present invention.

[0062] As Figure 3 shown, this embodiment provides a high-efficiency manufacturing method of a composite material based on the design of front polymerization initiation points, including the following steps: S10, preparing a first mixed solution of epoxy resin, diluent, photoinitiator, and thermal initiator.

[0063] Step S10 in this embodiment is substantially the same as that in Embodiment 1 and will not be repeated. The only difference is that the molar percentage concentrations of the photoinitiator I-Sb and the thermal initiator TPED in the first mixed solution of I-Sb / TPED / EOM / BADGE in Step S10 in this embodiment are both 2 mol%, and the molar ratio of the diluent EOM to the epoxy resin BADGE is 3:7.

[0064] B20. Heat the first mixture to a preset initial temperature of 30 °C to 70 °C to obtain a second epoxy resin front polymerization solution.

[0065] Among them, the heating operation is realized by an oven, a heating pad or a heating table.

[0066] Specifically in this embodiment, the preset initial temperature is selected as 50 °C, and the heating operation is realized by a vacuum oven, which can remove air bubbles from the second epoxy resin front polymerization solution while heating and keeping warm.

[0067] B30. Lay continuous fiber fillers in a mold.

[0068] Among them, the continuous fiber filler is a continuous fiber fabric, and the continuous fiber fabric includes any one or more of glass fiber, carbon fiber and plant fiber. The mass ratio of the continuous fiber filler to the second epoxy resin front polymerization solution is 5:95 to 35:65.

[0069] Specifically in this embodiment, the continuous fiber filler is a rectangular glass fiber fabric of 140 mm×16 mm, and the laying method of the glass fiber fabric in the mold is [0]8.

[0070] B40. After pouring the second epoxy resin front polymerization solution into the mold, according to the requirements of actual production for curing time and energy consumption, design the number and position arrangement of initiation points based on the polymerization front propagation speed.

[0071] Among them, the number of initiation points is the ratio of the total value of energy consumption to the energy consumption of a single initiation point. When the actual production requires the lowest energy consumption and curing time, approximate the curing area of the second epoxy resin front polymerization solution in the mold as a rectangular area of length multiplied by width. All polymerization fronts start from the initiation points, divide the area to be cured into squares with equal side lengths along the length and width respectively, and initiate polymerization fronts at the center positions of the squares simultaneously.

[0072] Specifically in this embodiment, considering that the mold is bar-shaped, the initiation points should be arranged along the direction of front polymerization spread, and the curing time should be less than 0.7 min. Through a single-point initiation front polymerization experiment, calculate the front polymerization propagation speed and curing time. The curing time of single-point initiation is 1.2 min. Therefore, two-point initiation of front polymerization can meet the requirements.

[0073] Figure 5 It is a schematic diagram of the initiation point arrangement design in Embodiment 3 of the present invention. The initiation point arrangement design in this step is as Figure 4 shown, and there are 2 initiation points in total. The 2 initiation points are arranged at both ends of the length direction of the rectangular mold.

[0074] After designing the number and position arrangement of the initiation points in this step, the entire mold is placed in a vacuum oven and kept at 50 °C for a period of time to remove air bubbles from the second epoxy resin front-end polymerization solution.

[0075] B50, initiate front-end polymerization, with exothermic self-propagation and curing.

[0076] Among them, through ultraviolet light irradiation or local heating, front-end polymerization is initiated at the position of the initiation points. After the front-end is initiated, the ultraviolet light or heating point is removed, and the polymerization front propagates self-exothermically by the heat released from the polymerization reaction. The second epoxy resin front-end polymerization solution rapidly cures from the initiation points at a propagation rate of not less than 2.7 cm / min and the degree of cure is greater than 95%, and finally a fully cured epoxy resin-based composite material is obtained.

[0077] Specifically in this embodiment, the method for initiating front-end polymerization is to use two ultraviolet light sources with a wavelength of 365 nm to irradiate the epoxy resin for 15 s simultaneously at the three initiation points determined in step B40 to initiate multi-point front-end polymerization. After the front-end is initiated, the ultraviolet light source is removed, and the polymerization front gradually diffuses outward from the initiation points until the resin is completely cured.

[0078] Comparative Example 1 The epoxy resin cured product in this comparative example was prepared according to a high-efficiency manufacturing method for composite materials based on the design of front-end polymerization initiation points provided in Example 1.

[0079] The preparation method in this comparative example includes steps S10, A30, A40, and A50. (Do not perform the addition of discrete fillers in step A20) Step S10 in this comparative example is generally similar to that in Example 1 and will not be repeated. The only difference is that in step S10 of this comparative example, the molar percentage concentrations of the photoinitiator I-Sb and the thermal initiator TPED in the finally prepared first mixed solution of I-Sb / TPED / EOM / BADGE are both 0.8 mol%.

[0080] Step A30 in this comparative example is generally similar to that in Example 1 and will not be repeated. The only difference is that the preset initial temperature in step A30 of this comparative example is selected as 30 °C.

[0081] Steps A40 and A50 in this comparative example are generally similar to those in the example and will not be repeated.

[0082] Comparative Example 2 The epoxy resin cured product in this comparative example was prepared according to a high-efficiency manufacturing method for composite materials based on the design of front-end polymerization initiation points provided in Example 1.

[0083] The preparation method in this comparative example includes steps S10, A30, A40, and A50. (The addition of discrete fillers in step A20 is not carried out.) Step S10 in this comparative example is generally similar to that in Example 1 and will not be repeated. The only difference is that: in step S10 of this comparative example, the molar percentage concentrations of both the photoinitiator I-Sb and the thermal initiator TPED in the finally prepared first mixed solution of I-Sb / TPED / EOM / BADGE are 0.8 mol%.

[0084] Step A30 in this comparative example is generally similar to that in Example 1 and will not be repeated. The only difference is that: the preset initial temperature in step A30 of this comparative example is selected as 30 °C.

[0085] Step A40 in this comparative example is generally similar to that in Example 1 and will not be repeated. The only difference is that: the number of initiation points in step A40 of this comparative example is only 1.

[0086] Step A50 in this comparative example is generally similar to that in the example and will not be repeated.

[0087] Comparative Example 3 This comparative example prepares an epoxy resin-based composite material according to a high-efficiency manufacturing method of a composite material based on the design of a front-end polymerization initiation point provided in Example 3.

[0088] The preparation method in this comparative example includes steps S10, B20, B30, B40, and B50.

[0089] Steps S10, B20, B30, B40, and B50 in this comparative example are generally similar to those in Example 3 and will not be repeated. The only difference is that: the number of initiation points in this comparative example is 1.

[0090] Step B50 in this comparative example is generally similar to that in the example and will not be repeated.

[0091] Comparative Example 4 This comparative example uses the traditional thermal curing method to mold epoxy resin. The epoxy resin selected in this case is the same as that in the implementation case, but the difference is that 4,4′-diaminodiphenylmethane (DDM) is selected as the curing agent, and it is cured and molded by heating at 100 °C for 2 h and 150 °C for 2 h.

[0092] Comparative Example 5 This comparative example uses the traditional thermal curing method to mold an epoxy resin / glass fiber fabric composite material. The epoxy resin and fiber selected in this case are the same as those in Example 3, but the difference is that 4,4′-diaminodiphenylmethane (DDM) is selected as the curing agent, and it is cured and molded by heating at 100 °C for 2 h and 150 °C for 2 h.

[0093] Test Example The composite materials prepared in Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2, Comparative Example 3, Comparative Example 4, and Comparative Example 5 were respectively denoted as Sample 1, Sample 2, Sample 3, Comparative Sample 1, Comparative Sample 2, Comparative Sample 3, Comparative Sample 4, and Comparative Sample 5.

[0094] Among them, Sample 1 is an epoxy resin / carbon nanotube composite material, Sample 2 is an epoxy resin / chopped glass fiber composite material, Sample 3 is an epoxy resin / glass fiber fabric composite material, Comparative Samples 1 and 2 are epoxy resins with different numbers of initiation points, Comparative Sample 3 is a single-point initiated epoxy resin / glass fiber fabric composite material, and Comparative Samples 4 and 5 are epoxy resins and composite materials prepared by the traditional thermal curing method.

[0095] In this test example, corresponding tests were carried out on Sample 1, Sample 2, Sample 3, Comparative Sample 1, Comparative Sample 2, Comparative Sample 3, Comparative Sample 4, and Comparative Sample 5.

[0096] Figure 6 It is the SEM image of Comparative Sample 1 in the test example of the present invention.

[0097] As Figure 6 shown, the internal structure of the front-end polymerized epoxy resin of Comparative Sample 1 is dense and there are no obvious pores. Therefore, the front-end polymerization has extremely little influence on the microscopic morphology of the epoxy resin.

[0098] Figure 7 It is the comparison of the flexural properties of Comparative Samples 1 and 2 in the test example of the present invention.

[0099] As Figure 7 shown, compared with the single-point initiated front-end polymerized epoxy resin of Comparative Sample 2, the flexural property of the front-end polymerized epoxy resin of Comparative Sample 1 has a relatively higher flexural strength. The high front-end temperature at the merging position increases the crosslinking density of the epoxy resin and effectively improves the mechanical properties of the epoxy resin. The high front-end temperature in the front-end merging region increases the crosslinking density of the epoxy resin and further improves the flexural strength of the epoxy resin.

[0100] Figure 8 It is the comparison of the flexural properties of Sample 3 and Comparative Sample 3 in the test example of the present invention.

[0101] As Figure 8 shown, in the case of adding continuous fillers, compared with Comparative Sample 3 with single-point initiation, the flexural strength of Sample 3 with multi-point initiation does not decrease significantly (multi-point initiation has little influence on the mechanical properties of the composite material).

[0102] As Figure 7 and Figure 8As shown, compared with the front-end polymerized epoxy resin of Comparative Sample 1, the flexural properties of the front-end polymerized epoxy resin matrix composite of Sample 3 are significantly improved, and the addition of fibers effectively improves the mechanical properties of the sample.

[0103] In this test example, the DSC method was used to calculate the curing degrees of Sample 1, Sample 2, and Sample 3 obtained by multi-point initiated front-end polymerization, which were 97.3%, 98.1%, and 96.9% respectively. From the above data, it can be seen that the curing degrees of the composites of Sample 1, Sample 2, and Sample 3 are all higher than 95%. This indicates that the multi-point initiated front-end polymerized epoxy resin and composites prepared by an efficient manufacturing method of composites based on the design of front-end polymerization initiation points in the examples can achieve complete curing.

[0104] This test example also tested the curing time and curing energy consumption of Sample 1, Sample 2, and Sample 3. The test results are as follows: the curing time of Sample 1 is 1.92 min, and the energy consumption is 2025 J; the curing time of Sample 2 is 0.88 min, and the energy consumption is 4050 J; the curing time of Sample 3 is 0.63 min, and the energy consumption is 1350 J. From the above data, it can be seen that the epoxy resin composites of Sample 1, Sample 2, and Sample 3 are cured within 3 min, and the energy consumption is less than 5000 J. The curing time and energy consumption of Comparative Sample 4 are 4 h and 43.2 MG, and the curing time and energy consumption of Comparative Sample 5 are also 4 h and 43.2 MG. Therefore, through front-end polymerization in the examples, the curing time of traditional epoxy resin and composites is shortened from several hours to several minutes, and the energy consumption is shortened from several hours of high-temperature input to 15 s of ultraviolet light energy input.

[0105] Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification is only to illustrate the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for efficient manufacturing of composite materials based on the design of front-end polymerization initiation points, characterized in that Including the following steps: S10, prepare a first mixed solution of epoxy resin, diluent, photoinitiator and thermal initiator. Among them, the molar percentage concentration of the photoinitiator in the first mixed solution is 0.5 mol% - 5.5 mol%, the molar percentage concentration of the thermal initiator in the first mixed solution is 0.5 mol% - 5.5 mol%, the molar ratio of the diluent to the epoxy resin is (2 - 3):(7 - 8), the photoinitiator is 4-(octyloxyphenyl)phenyl iodonium hexafluoroantimonate and / or tetraalkyl(perfluorotert-butoxy)aluminate anion, the thermal initiator is benzoin pinacol, and the epoxy resin is bisphenol A diglycidyl ether; A20, add discrete fillers to the first mixed solution and mix evenly to obtain a second mixed solution. The discrete fillers are reinforcing and functional fillers, and the mass fraction of the discrete fillers in the second mixed solution is 0.5 wt% - 35 wt%; A30, heat the second mixed solution to a preset initial temperature of 30 °C - 70 °C to obtain a first epoxy resin front polymerization solution; A40, after pouring the first epoxy resin front polymerization solution into a mold, according to the requirements of actual production for curing time and energy consumption, design the number and position arrangement of initiation points based on the propagation speed of the polymerization front; A50, initiate front polymerization at the position of the initiation point by ultraviolet light irradiation or local heating. After the front is initiated, remove the ultraviolet light or heating point. The polymerization front propagates self-exothermically by the polymerization reaction. The first epoxy resin front polymerization solution rapidly cures from the initiation point at a spreading rate of not less than 2.5 cm / min and the degree of cure is greater than 95%, and finally a fully cured epoxy resin is obtained.

2. An efficient manufacturing method for composite materials based on the design of front-end polymerization initiation points, characterized in that, Including the following steps: S10, prepare a first mixed solution of epoxy resin, diluent, photoinitiator and thermal initiator. Among them, the molar percentage concentration of the photoinitiator in the first mixed solution is 0.5 mol% - 5.5 mol%, the molar percentage concentration of the thermal initiator in the first mixed solution is 0.5 mol% - 5.5 mol%, the molar ratio of the diluent to the epoxy resin is (2 - 3):(7 - 8), the photoinitiator is 4-(octyloxyphenyl)phenyl iodonium hexafluoroantimonate and / or tetraalkyl(perfluorotert-butoxy)aluminate anion, the thermal initiator is benzoin pinacol, and the epoxy resin is bisphenol A diglycidyl ether; B20, heat the first mixed solution to a preset initial temperature of 30 °C - 70 °C to obtain a second epoxy resin front polymerization solution; B30, lay continuous fiber fillers in the mold. The continuous fiber fillers are continuous fiber fabrics, and the mass ratio of the continuous fiber fillers to the second epoxy resin front polymerization solution is 5:95 - 35:65; B40, after pouring the second epoxy resin front polymerization solution into a mold, according to the requirements of actual production for curing time and energy consumption, design the number and position arrangement of initiation points based on the propagation speed of the polymerization front; B50, initiate frontal polymerization at the position of the initiation point by means of ultraviolet irradiation or local heating. After the front is initiated, remove the ultraviolet light or the heating point. The polymerization front propagates self-heat by the exothermic polymerization reaction. The second epoxy resin frontal polymerization solution rapidly cures from the initiation point at a spreading rate of not less than 2.7 cm / min and the degree of cure is greater than 95%, and finally a fully cured epoxy resin-based composite material is obtained.

3. The method for efficiently manufacturing a composite material based on the design of a frontal polymerization initiation point according to claim 1 or 2, characterized in that: Among them, Step S10 includes the following sub-steps: S11, put a photoinitiator and a thermal initiator into an organic solvent and stir at high speed until dissolved to obtain an initiator solution; S12, put epoxy resin and a diluent into the initiator solution, mix evenly, and then discharge the organic solvent to obtain a first mixture.

4. The method for efficiently manufacturing a composite material based on the design of a frontal polymerization initiation point according to claim 3, characterized in that: Among them, In step S11, the organic solvent includes dichloromethane and / or ethyl acetate.

5. The method for efficiently manufacturing a composite material based on the design of a frontal polymerization initiation point according to claim 1 or 2, characterized in that: Among them, In step S10, the diluent includes any one or more of 3-ethyl-3-oxetane methanol, glycidyl neopentyl glycol diglycidyl ether, hexanediol diglycidyl ether, cyclohexanedimethanol, and cyclohexyl epoxy ester.

6. The method for efficiently manufacturing a composite material based on the design of a frontal polymerization initiation point according to claim 1 or 2, characterized in that: Among them, In step S10, the molar ratio of the photoinitiator to the thermal initiator is 1:0.5 to 1:

2.

7. The method for efficiently manufacturing a composite material based on the design of a frontal polymerization initiation point according to claim 1 or 2, characterized in that: Among them, In step A30 or step B20, the heating operation is realized by an oven, a heating pad or a heating table.

8. The method for efficiently manufacturing a composite material based on the design of a frontal polymerization initiation point according to claim 1 or 2, characterized in that: Among them, In step A30 or step B40, vacuum degassing treatment is also performed on the first epoxy resin frontal polymerization solution or the second epoxy resin frontal polymerization solution.

9. The method for efficiently manufacturing a composite material based on the design of a frontal polymerization initiation point according to claim 1 or 2, characterized in that: Among them, In step A40 or step B40, the number of the initiation points is the ratio of the total value of the energy consumption to the energy consumption of a single initiation point. When the actual production requires the lowest energy consumption and curing time, approximate the curing area of the first epoxy resin frontal polymerization solution or the second epoxy resin frontal polymerization solution in the mold as a rectangular area of length multiplied by width. All polymerization fronts start from the initiation points. Divide the area to be cured into squares with equal side lengths along the length and width respectively, and initiate polymerization fronts at the center positions of the squares simultaneously.

10. The method for efficiently manufacturing a composite material based on the design of a frontal polymerization initiation point according to claim 1 or 2, characterized in that: Among them, In step A50 or step B50, when the way to initiate the front-end polymerization is ultraviolet light irradiation, the wavelength of the ultraviolet light source is 365 nm, and the irradiation time is 15 s to 20 s. When the way to initiate the front-end polymerization is local heating, the implementation methods of local heating include soldering iron heating or laser heating.

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