A low glass transition temperature epoxy resin prepreg, its preparation method and application

Abstract

The application provides a low glass transition temperature epoxy resin prepreg, which comprises 40-75% of a fiber reinforced material and 25%-60% of an epoxy resin formula glue; the epoxy resin formula glue comprises one or two of bisphenol A type liquid epoxy resin, bisphenol A type solid epoxy resin, phenoxy resin, polyethylene glycol or a difunctional epoxy diluent, a dicyandiamide curing agent and a substituted urea accelerator. The application solves the industry problems of high threading operation temperature and large energy consumption by reducing the glass transition temperature of the epoxy resin prepreg to about 85 DEG C, and the room temperature mechanical properties of the material are also considered.

Description

[Technical Field]

[0001] This invention relates to the field of fiber-reinforced composite materials, specifically to a low glass transition temperature epoxy resin prepreg, its preparation method, and its application. [Background Technology]

[0002] Epoxy resin is a high molecular polymer with excellent physical, mechanical and electrical insulation properties, and can be bonded to various materials; therefore, epoxy resin can be combined with fibers to make fiber-reinforced composite materials.

[0003] The glass transition temperature (Tg) is the temperature at which a material transitions from a glassy state to a highly elastic state. It directly affects the material's performance in use and processing, and has therefore long been a major focus of polymer physics research. For example, in the field of composite materials, some composite products require threading during assembly. However, the glass transition temperature (Tg) of traditional fiber-reinforced composites is typically higher than 120°C. Fiber-reinforced composites only soften after the temperature exceeds the glass transition temperature, meaning that threading operations must be performed at temperatures above 120°C, resulting in high energy consumption and safety risks.

[0004] In view of this, the inventors of this case conducted in-depth research on the above-mentioned problems, which led to the creation of this case. [Summary of the Invention]

[0005] This invention aims to solve the technical problem of excessively high glass transition temperature and safety issues during threading operations of traditional fiber-reinforced composite materials. In order to maintain the mechanical properties of the composite material at room temperature while softening the material at a relatively low temperature for threading operations, this invention provides an epoxy resin prepreg that can reduce the glass transition temperature.

[0006] The present invention is achieved as follows: a low glass transition temperature epoxy resin prepreg, characterized in that it comprises 40-75% fiber reinforcement material and 25%-60% epoxy resin formulation adhesive.

[0007] Furthermore, the epoxy resin formulation includes one or two of the following: bisphenol A type liquid epoxy resin, bisphenol A type solid epoxy resin, phenoxy resin, polyethylene glycol or bifunctional epoxy diluent, dicyandiamide curing agent, and substituted urea promoter.

[0008] Furthermore, the bisphenol A type liquid epoxy resin and bisphenol A type solid epoxy resin together account for 77.7-83.1% of the epoxy resin formulation; the phenoxy resin accounts for 1.7-7.8% of the epoxy resin formulation; one or two of the polyethylene glycol or difunctional epoxy diluents account for 8.3-10% of the epoxy resin formulation; the dicyandiamide curing agent accounts for 2.1-4.4% of the epoxy resin formulation; and the urea-replacing agent accounts for 0.8-2.0% of the epoxy resin formulation.

[0009] Furthermore, the polyethylene glycol accounts for 8.3% of the epoxy resin formulation.

[0010] Furthermore, the bifunctional epoxy diluent accounts for 10% of the epoxy resin formulation.

[0011] Furthermore, the fiber-reinforcing material includes, but is not limited to, one or more of basalt fiber, glass fiber, and aramid fiber.

[0012] On the other hand, a method for preparing the aforementioned low glass transition temperature epoxy resin prepreg is characterized by comprising the following steps:

[0013] Step 1: Preparing the epoxy resin formulation: Heat and melt one or two of the following: bisphenol A type liquid epoxy resin, bisphenol A type solid epoxy resin, and polyethylene glycol or bifunctional epoxy diluent, setting the temperature between 90-135℃. After melting, place the mixture in a mixer and stir for 30-90 minutes, with vacuum applied during the stirring process, and control the speed at 600-1000 rpm. After stirring, cool the temperature to 60-80℃. Add dicyandiamide curing agent and urea-replacing accelerator, and stir for another 10-30 minutes, controlling the temperature below 80℃ during stirring. The epoxy resin formulation is now ready.

[0014] Step 2: Coating: Set the equipment temperature to 70±5℃, and evenly coat the prepared epoxy resin formula onto the release paper to form a film;

[0015] Step 3: Place the coated film on the top and bottom, lay the fiber reinforcement material in the middle, and heat it appropriately, controlling the temperature at 90-120℃; after pressing and cooling, roll it up to obtain the low glass transition temperature epoxy resin prepreg.

[0016] On the other hand, the application of a low glass transition temperature epoxy resin prepreg is described, in which the low glass transition temperature epoxy resin prepreg is used to prepare ice skate shells.

[0017] On the other hand, the application of a low glass transition temperature epoxy resin prepreg is described, which is used to prepare composite shoes.

[0018] On the other hand, the application of a low glass transition temperature epoxy resin prepreg is to use the low glass transition temperature epoxy resin prepreg to prepare carbon fiber leisure sports products, carbon fiber bags or foldable composite material products, etc.

[0019] The advantages of this invention are:

[0020] 1. This invention uses polyethylene glycol and a mixture of two or more difunctional epoxy diluents to adjust the glass transition temperature of epoxy resin prepreg; and uses bisphenol A type liquid epoxy resin to adjust the viscosity, thereby reducing the glass transition temperature of epoxy resin prepreg to about 85°C, thus solving the industry problem of high temperature and high energy consumption in threading operations.

[0021] 2. The epoxy resin prepreg of the present invention has both good mechanical strength and rigidity at room temperature, and can significantly reduce material rigidity at temperatures above 85°C to facilitate puncture, bending and other operations.

[0022] 3. When the epoxy resin prepreg of the present invention is used to prepare composite shoes, after the glass transition temperature is lowered to about 85°C, the composite shoes can be placed in boiling water to correct their shape. After the water cools down, the composite shoes can be shaped. [Attached Image Description]

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0024] Figure 1 These are data curves showing the heat released, initial reaction temperature, and peak reaction temperature during DSC testing in five embodiments of this invention.

[0025] Figure 2 These are data curves of glass transition temperature measured by DSC in five embodiments of this invention.

[0026] Figure 3 These are data curves showing the heat released, initial reaction temperature, and peak reaction temperature during the three comparative DSC tests in this invention.

[0027] Figure 4 These are data curves of the glass transition temperature from three comparative DSC tests in this invention.

[0028] Figure 5 This is a flowchart of the preparation method of low glass transition temperature epoxy resin prepreg in this invention.

Detailed Implementation Methods

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to represent selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Traditional fiber-reinforced epoxy resin prepregs typically have a glass transition temperature (Tg) above 120°C. However, threading operations must be performed at temperatures exceeding 120°C, resulting in high energy consumption and safety risks. This invention solves the industry problem of high temperatures and energy consumption in threading operations by lowering the glass transition temperature (Tg) of epoxy resin prepregs to approximately 85°C, while also maintaining the material's room-temperature mechanical properties. A glass transition temperature (Tg) that is too low is also undesirable, as a lower Tg would compromise the material's room-temperature mechanical strength, negating the benefits of fiber reinforcement.

[0031] This invention provides a low glass transition temperature epoxy resin prepreg, comprising 40-75% fiber reinforcement and 25%-60% epoxy resin formulation.

[0032] In this invention, the epoxy resin formulation comprises one or two of the following: bisphenol A type liquid epoxy resin, bisphenol A type solid epoxy resin, phenoxy resin, polyethylene glycol, or a dimethyl diluent, dicyandiamide curing agent, and a substituted urea-promoting agent. Polyethylene glycol and one or two of the dimethyl diluent are used in combination to adjust the glass transition temperature of the epoxy resin formulation, while bisphenol A type liquid epoxy resin and bisphenol A type solid epoxy resin are used to adjust the viscosity of the epoxy resin formulation.

[0033] Traditional processes use liquid and solid epoxy resins to create epoxy resin formulations. If you touch the formulation and immediately remove your hand, the epoxy resin won't stick. However, if you hold it for 5-10 seconds, the epoxy resin will be picked up by your hand. To address this issue, this invention adds phenoxy resin to the epoxy resin formulation. This prevents the epoxy resin from sticking to your hand even after prolonged contact, thus adjusting the formulation's tackiness.

[0034] In this invention, the combined proportion of bisphenol A type liquid epoxy resin and bisphenol A type solid epoxy resin in the epoxy resin formulation is 77.7-83.1%; the proportion of phenoxy resin in the epoxy resin formulation is 1.7-7.8%; the proportion of one or both of polyethylene glycol or difunctional epoxy diluents in the epoxy resin formulation is 8.3-10%; the proportion of dicyandiamide curing agent in the epoxy resin formulation is 2.1-4.4%; and the proportion of substituted urea promoter in the epoxy resin formulation is 0.8-2.0%. The epoxy resin formulation employs a unique design that maintains room temperature mechanical properties while reducing the glass transition temperature to approximately 85°C.

[0035] In this invention, the bisphenol A type liquid epoxy resin was purchased from Nan Ya Epoxy Resin (Kunshan) Co., Ltd., model NPEL-128; the bisphenol A type solid epoxy resin was purchased from Nan Ya Epoxy Resin (Kunshan) Co., Ltd., model NPES-901; the polyethylene glycol was purchased from Dow Chemical Company (USA), model PEG8000; the phenoxy resin was purchased from Huntsman, model PKHH; the bifunctional epoxy diluent was purchased from Anhui Xinyuan Technology Co., Ltd., model XY632; the dicyandiamide curing agent was purchased from Alzchem Group (Germany), model Dyhard 100S; and the urea-promoting agent was purchased from Alzchem Group (Germany), model Dyhard UR500.

[0036] In a preferred embodiment, the polyethylene glycol accounts for 8.3% of the epoxy resin formulation.

[0037] In another preferred embodiment, the bifunctional epoxy diluent accounts for 10% of the epoxy resin formulation.

[0038] In this invention, the fiber-reinforcing material includes, but is not limited to, one or more of basalt fiber, glass fiber, carbon fiber, and aramid fiber.

[0039] This invention also includes a method for preparing the low glass transition temperature epoxy resin prepreg, comprising the following steps:

[0040] Step 1: Preparing the epoxy resin formulation: Heat and melt one or two of the following: bisphenol A type liquid epoxy resin, bisphenol A type solid epoxy resin, phenoxy resin, and polyethylene glycol or bifunctional epoxy diluent, setting the temperature between 90-135℃. After melting, place the mixture in a mixer and stir for 30-90 minutes, with vacuum applied during the stirring process, and control the speed at 600-1000 rpm. After stirring, cool the temperature to 60-80℃. Add dicyandiamide curing agent and urea-replacing accelerator, and stir for another 10-30 minutes, controlling the temperature below 80℃ during stirring. The epoxy resin formulation is now ready.

[0041] Step 2: Coating: Set the equipment temperature to 70±5℃, and evenly coat the prepared epoxy resin formula onto the release paper to form a film;

[0042] Step 3: Place the coated film on the top and bottom, lay the fiber reinforcement material in the middle, and heat it appropriately, controlling the temperature at 90-120℃; after pressing and cooling, roll it up to obtain the low glass transition temperature epoxy resin prepreg.

[0043] The following examples and comparative examples further illustrate the beneficial effects of the low glass transition temperature epoxy resin prepreg obtained by adopting the technical solution of this embodiment.

[0044] Example 1

[0045] Formulating epoxy resin adhesive: Heat 41.3% bisphenol A type liquid epoxy resin, 41.3% bisphenol A type solid epoxy resin, 4.1% phenoxy resin, 5.8% polyethylene glycol, and 2.5% difunctional epoxy diluent together until melted at 90-135℃. After melting, place the mixture in a mixer and stir for 30-90 min, with vacuum applied during the stirring process and the speed controlled at 600-1000 r / min. After stirring, cool the mixture to 60-80℃. Add 4.1% dicyandiamide curing agent and 0.9% substituted urea accelerator, and stir for another 10-30 min, keeping the temperature below 80℃ during stirring. This will yield the epoxy resin adhesive. Coating: Set the equipment temperature to 70±5℃, and evenly coat the prepared epoxy resin formula onto the release paper to form a film; arrange the coated film on the top and bottom, lay the fiber reinforcement material in the middle, and heat it appropriately, controlling the temperature at 90-120℃; after pressing and cooling, roll it up to obtain the low glass transition temperature epoxy resin prepreg.

[0046] Example 2

[0047] Formulating epoxy resin adhesive: Heat 41.4% bisphenol A type liquid epoxy resin, 41.4% bisphenol A type solid epoxy resin, 4.1% phenoxy resin, and 8.3% polyethylene glycol together until melted at 90-135℃. After melting, place the mixture in a mixer and stir for 30-90 min, with vacuum applied during the stirring process and the speed controlled at 600-1000 r / min. After stirring, cool the temperature to 60-80℃. Add 3.9% dicyandiamide curing agent and 0.9% substituted urea accelerator, and stir for another 10-30 min, keeping the temperature below 80℃ during stirring. This will produce the epoxy resin adhesive. Coating: Set the equipment temperature to 70±5℃, and evenly coat the prepared epoxy resin formula onto the release paper to form a film; arrange the coated film on the top and bottom, lay the fiber reinforcement material in the middle, and heat it appropriately, controlling the temperature at 90-120℃; after pressing and cooling, roll it up to obtain the low glass transition temperature epoxy resin prepreg.

[0048] Example 3

[0049] Formulating epoxy resin adhesive: Heat and melt 24.9% bisphenol A type liquid epoxy resin, 58.2% bisphenol A type solid epoxy resin, 1.7% phenoxy resin, and 10% difunctional epoxy diluent together at a temperature of 90-135℃. After melting, place the mixture in a mixer and stir for 30-90 min, with vacuum applied during the stirring process and the speed controlled at 600-1000 r / min. After stirring, cool the temperature to 60-80℃. Add 4.4% dicyandiamide curing agent and 0.8% substituted urea accelerator, and stir for another 10-30 min, keeping the temperature below 80℃ during stirring. This will yield the epoxy resin adhesive. Coating: Set the equipment temperature to 70±5℃, and evenly coat the prepared epoxy resin formula onto the release paper to form a film; arrange the coated film on the top and bottom, lay the fiber reinforcement material in the middle, and heat it appropriately, controlling the temperature at 90-120℃; after pressing and cooling, roll it up to obtain the low glass transition temperature epoxy resin prepreg.

[0050] Example 4

[0051] Formulating epoxy resin adhesive: Heat 54.4% bisphenol A type liquid epoxy resin, 23.3% bisphenol A type solid epoxy resin, 7.8% phenoxy resin, 8.5% polyethylene glycol, and 0.8% difunctional epoxy diluent together until melted at 90-135℃. After melting, place the mixture in a mixer and stir for 30-90 min, with vacuum applied during the stirring process and the speed controlled at 600-1000 r / min. After stirring, cool the temperature to 60-80℃. Add 4.4% dicyandiamide curing agent and 0.8% substituted urea accelerator, and stir for another 10-30 min, keeping the temperature below 80℃ during stirring. This will yield the epoxy resin adhesive. Coating: Set the equipment temperature to 70±5℃, and evenly coat the prepared epoxy resin formula onto the release paper to form a film; arrange the coated film on the top and bottom, lay the fiber reinforcement material in the middle, and heat it appropriately, controlling the temperature at 90-120℃; after pressing and cooling, roll it up to obtain the low glass transition temperature epoxy resin prepreg.

[0052] Example 5

[0053] Formulating epoxy resin adhesive: Heat 40.6% bisphenol A type liquid epoxy resin, 40.6% bisphenol A type solid epoxy resin, 4.9% phenoxy resin, 4.9% polyethylene glycol, and 4.9% difunctional epoxy diluent together until melted at 90-135℃. After melting, place the mixture in a mixer and stir for 30-90 min, with vacuum applied during the stirring process and the speed controlled at 600-1000 r / min. After stirring, cool the temperature to 60-80℃. Add 2.1% dicyandiamide curing agent and 2.0% substituted urea accelerator, and stir for another 10-30 min, keeping the temperature below 80℃ during stirring. This will yield the epoxy resin adhesive. Coating: Set the equipment temperature to 70±5℃, and evenly coat the prepared epoxy resin formula onto the release paper to form a film; arrange the coated film on the top and bottom, lay the fiber reinforcement material in the middle, and heat it appropriately, controlling the temperature at 90-120℃; after pressing and cooling, roll it up to obtain the low glass transition temperature epoxy resin prepreg.

[0054] Comparative Example 1

[0055] Epoxy resin formulation: Melt 47.3% bisphenol A type liquid epoxy resin and 47.3% bisphenol A type solid epoxy resin together at a temperature of 90-135℃. After melting, stir in a mixer for 30-90 minutes, with vacuum applied during stirring, and maintain a speed of 600-1000 rpm. After stirring, cool to 60-80℃. Add 4.5% dicyandiamide curing agent and 0.9% substituted urea accelerator, and stir for another 10-30 minutes, maintaining a temperature below 80℃ during stirring. This yields the epoxy resin formulation. Coating: Set the equipment temperature to 70±5℃. Evenly coat the prepared epoxy resin formulation onto release paper to form a film. Arrange the coated films on both sides, with fiber reinforcement material in the middle, and heat appropriately at a temperature of 90-120℃. Press, cool, and then wind up to obtain the low glass transition temperature epoxy resin prepreg.

[0056] Comparative Example 2

[0057] Epoxy resin formulation: Melt 28.7% bisphenol A liquid epoxy resin and 67.0% bisphenol A solid epoxy resin together at a temperature of 90-135℃. After melting, stir in a mixer for 30-90 minutes under vacuum, controlling the speed at 600-1000 rpm. After stirring, cool to 60-80℃. Add 2.4% dicyandiamide curing agent and 1.9% substituted urea accelerator, then stir for another 10-30 minutes, maintaining the temperature below 80℃. This yields the epoxy resin formulation. Coating: Set the equipment temperature to 70±5℃. Evenly coat the prepared epoxy resin formulation onto release paper to form a film. Arrange the coated films on top and bottom, with fiber reinforcement material in the middle, and heat moderately at 90-120℃. Press, cool, and then wind up to obtain the low glass transition temperature epoxy resin prepreg.

[0058] Comparative Example 3

[0059] Epoxy resin formulation: Melt 66.0% bisphenol A liquid epoxy resin and 28.3% bisphenol A solid epoxy resin together at a temperature of 90-135℃. After melting, stir in a mixer for 30-90 minutes under vacuum, controlling the speed at 600-1000 rpm. After stirring, cool to 60-80℃. Add 5.1% dicyandiamide curing agent and 0.6% substituted urea accelerator, then stir for another 10-30 minutes, maintaining the temperature below 80℃. This yields the epoxy resin formulation. Coating: Set the equipment temperature to 70±5℃. Evenly coat the prepared epoxy resin formulation onto release paper to form a film. Arrange the coated films on top and bottom, with fiber reinforcement material in the middle, and heat appropriately at 90-120℃. Press, cool, and then wind up to obtain the low glass transition temperature epoxy resin prepreg.

[0060] The reactivity and heat resistance of the epoxy resin prepregs prepared in the five examples and three comparative examples were tested using differential scanning calorimetry (DSC).

[0061] Table 1. Test data of DSC used in each group of examples and comparative examples.

[0062] Example 1 289.2 134.02 150.95 84.7 Example 2 266.8 135.82 151.04 86.67 Example 3 254.5 134.75 153.47 86.86 Example 4 263.6 135.05 152.21 85.69 Example 5 252.7 135.14 152.58 86.26 Comparative Example 1 375.6 142.2 152.64 123.79 Comparative Example 2 379.5 135.79 147.75 126.43 Comparative Example 3 371.4 143.04 152.56 123.33

[0063] Examples 1 to 5 correspond to the appendices in sequence. Figure 1 and 2 Test1 through Test5.

[0064] Comparative Examples 1 to 3 correspond to the appendices in order. Figure 3 and 4 Blank1 to Blank3 in the middle.

[0065] In the appendix Figure 1-4 In the diagram, the horizontal axis represents temperature, the vertical axis represents heat flux, and the Enthalpy (j / g) value indicates the heat released during the reaction (see appendix). Figure 1 and attached Figure 3 The area enclosed by the initial reaction temperature, peak temperature, and final reaction temperature of the curve represents the heat released during the reaction (T). onset T represents the initial reaction temperature. max Tg represents the peak reaction temperature, and Tg represents the glass transition temperature.

[0066] In the appendix Figure 1 In the figure, the peaks of the five curves are used to determine the temperature. From top to bottom, the five curves represent Example 1 (150.95℃), Example 2 (151.04℃), Example 4 (152.21℃), Example 5 (152.58℃), and Example 3 (153.47℃).

[0067] In the appendix Figure 2 In the figure, the five curves from top to bottom represent Example 1 (84.7℃), Example 2 (86.67℃), Example 3 (86.86℃), Example 4 (85.69℃), and Example 5 (86.26℃).

[0068] In the appendix Figure 3 In the middle, the order in which the peaks of the three curves appear is used to determine the temperature. From left to right, the three curves represent Comparative Example 2 (147.75℃), Comparative Example 3 (152.56℃), and Comparative Example 1 (152.64℃).

[0069] In the appendix Figure 4 In the figure, the three curves from top to bottom represent Comparative Example 1 (123.79℃), Comparative Example 2 (126.43℃), and Comparative Example 1 (123.33℃).

[0070] As shown in Table 1, compared with traditional epoxy resin prepregs (three comparative examples), the epoxy resin prepregs prepared by the method of the present invention (five examples) not only significantly reduce the heat released during the epoxy resin reaction, but also lower the glass transition temperature from over 120°C to around 85°C. Therefore, the present invention effectively reduces the glass transition temperature of epoxy resin prepregs by using one or a mixture of polyethylene glycol and difunctional epoxy diluents.

[0071] The present invention also includes the application of a low glass transition temperature epoxy resin prepreg, which is used to prepare an ice skate shell.

[0072] The present invention also includes another application of a low glass transition temperature epoxy resin prepreg, which is used to prepare carbon fiber leisure sports products, carbon fiber bags or foldable composite material products.

[0073] The present invention also includes another application of epoxy resin prepreg with low glass transition temperature. For example, a composite shoe can be prepared by lowering the glass transition temperature to about 85°C. The composite shoe can be placed in boiling water to correct its shape. The composite shoe can be set after the water cools down.

[0074] While specific embodiments of the present invention have been described above, those skilled in the art should understand that the specific embodiments described are merely illustrative and not intended to limit the scope of the present invention. Equivalent modifications and variations made by those skilled in the art in accordance with the spirit of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A low glass transition temperature epoxy resin prepreg, characterized in that: It includes 40-75% fiber-reinforced materials and 25%-60% epoxy resin formulations; The epoxy resin formulation comprises one or two of the following: bisphenol A type liquid epoxy resin, bisphenol A type solid epoxy resin, phenoxy resin, polyethylene glycol or difunctional epoxy diluent, dicyandiamide curing agent, and a substituted urea-accelerator; the combined proportion of the bisphenol A type liquid epoxy resin and bisphenol A type solid epoxy resin is 77.7-83.1% of the epoxy resin formulation; the phenoxy resin accounts for 1.7-7.8% of the epoxy resin formulation; the proportion of one or two of the following: polyethylene glycol or difunctional epoxy diluent is 8.3-10% of the epoxy resin formulation; the dicyandiamide curing agent accounts for 2.1-4.4% of the epoxy resin formulation; and the substituted urea-accelerator accounts for 0.8-2.0% of the epoxy resin formulation. The preparation method of the low glass transition temperature epoxy resin prepreg includes the following steps: Step 1: Preparing the epoxy resin formulation: Heat and melt one or two of the following: bisphenol A type liquid epoxy resin, bisphenol A type solid epoxy resin, phenoxy resin, and polyethylene glycol or bifunctional epoxy diluent, setting the temperature between 90-135℃. After melting, place the mixture in a mixer and stir for 30-90 minutes, with vacuum applied during the stirring process, and control the speed at 600-1000 rpm. After stirring, cool the temperature to 60-80℃. Add dicyandiamide curing agent and urea-replacing accelerator, and stir for another 10-30 minutes, controlling the temperature below 80℃ during stirring. The epoxy resin formulation is now ready. Step 2: Coating: Set the equipment temperature to 70±5℃, and evenly coat the prepared epoxy resin formula onto the release paper to form a film; Step 3: Place the coated film on the top and bottom, lay the fiber reinforcement material in the middle, and heat it appropriately, controlling the temperature at 90-120℃; after pressing and cooling, roll it up to obtain the low glass transition temperature epoxy resin prepreg.

2. The low glass transition temperature epoxy resin prepreg as described in claim 1, characterized in that: The polyethylene glycol accounts for 8.3% of the epoxy resin formulation.

3. The low glass transition temperature epoxy resin prepreg as described in claim 1, characterized in that: The bifunctional epoxy diluent accounts for 10% of the epoxy resin formulation.

4. The low glass transition temperature epoxy resin prepreg as described in claim 1, characterized in that: The fiber-reinforced material includes one or more of basalt fiber, glass fiber, and aramid fiber.

5. An application of a low glass transition temperature epoxy resin prepreg, characterized in that: The low glass transition temperature epoxy resin prepreg described in any one of claims 1-4 is used to prepare the ice skate shell.

6. An application of a low glass transition temperature epoxy resin prepreg, characterized in that: The low glass transition temperature epoxy resin prepreg described in any one of claims 1-4 is used to prepare composite shoes.

7. An application of a low glass transition temperature epoxy resin prepreg, characterized in that: The low glass transition temperature epoxy resin prepreg described in any one of claims 1-4 is used to prepare carbon fiber leisure sports products, carbon fiber bags, or foldable composite material products.

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