Epoxy resin composition and high heat resistant high strength high toughness epoxy prepreg

Abstract

The present application provides an epoxy resin composition and an epoxy prepreg prepared therefrom, the epoxy resin composition comprising: Component A: an epoxy prepolymer prepared from raw materials comprising a first epoxy compound, an optional second epoxy compound and a first curing agent, the first epoxy compound being an aromatic compound comprising at least three epoxy groups, the second epoxy compound comprising at least one epoxy compound different from the first epoxy compound, the first curing agent being a liquid aromatic amine; Component B: an epoxy resin having a composition different from the prepolymer; Component C: a second curing agent; and Component D: an accelerator; the epoxy resin composition not comprising a thermoplastic resin-based toughener. The epoxy prepreg prepared using the epoxy resin composition can exhibit excellent high-temperature resistance, tensile strength and flexibility, and has excellent high-temperature solubility, compatibility and ideal viscosity.

Description

Technical Field

[0001] This application relates to the field of polymers, and more specifically to epoxy resin compositions, epoxy prepregs prepared using the epoxy resin compositions, methods for preparing the epoxy prepregs, and products prepared using the prepregs. Background Technology

[0002] Curable epoxy resin materials prepared using epoxy compounds as raw materials can be used as high-performance, high-temperature resistant prepregs. After being cast into various materials or combined with various reinforcing fiber materials, these prepregs can produce products with very light weight, excellent mechanical strength, and high-temperature resistance. They are used in various fields, such as vehicles, building materials, ships, and freight transportation, and are playing an increasingly important role in fields such as aerospace and rail transportation that require exposure to harsher working environments.

[0003] Existing high-temperature resistant epoxy prepregs typically use one or more of tetrafunctional epoxy resins and phenolic epoxy resins as the base resin. However, such materials often exhibit high brittleness, requiring the addition of a significant proportion of thermoplastic resins as toughening agents. These thermoplastic toughening agents invariably require temperatures above 150°C to dissolve in the system, significantly increasing the difficulty of prepreg preparation. Furthermore, the poor compatibility between these thermoplastic toughening agents and the base resin results in significant overall inhomogeneity in the final prepreg, potentially leading to substantial performance degradation in the prepreg products. To address these issues, manufacturers and researchers in related fields have invested considerable resources in material development, but so far, no prepreg formulation has been reported that solves these problems. Additionally, it is generally accepted in existing technologies that trifunctional epoxy resins have low viscosity, making them unsuitable as a base resin for prepregs.

[0004] To address the aforementioned problems, the inventors of this application conducted in-depth research and developed a novel epoxy resin composition that can be used to prepare epoxy prepregs with stringent requirements for various applications through polymerization reactions. Furthermore, these prepregs can be used to prepare products with excellent performance, thereby completing this invention. Summary of the Invention

[0005] The first aspect of this application provides an epoxy resin composition comprising:

[0006] Component A: Epoxy prepolymer, which is prepared from raw materials including: a first epoxy compound, an optional second epoxy compound and a first curing agent, wherein the first epoxy compound is an aromatic compound containing at least three epoxy groups, the second epoxy compound includes at least one epoxy compound different from the first epoxy compound, and the first curing agent is a liquid aromatic amine;

[0007] Component B: Epoxy resin, the composition of which differs from that of the prepolymer;

[0008] Component C: Second curing agent; and

[0009] Component D: Accelerator;

[0010] The epoxy resin composition does not contain thermoplastic resin toughening agents.

[0011] According to one embodiment of the first aspect of this application, the first epoxy compound includes a compound represented by Formula I, a compound represented by Formula II, or a compound represented by both Formula I and Formula II:

[0012]

[0013] In equations I and II above, R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 R 11 and R 12 Each is independently selected from: hydrogen, C1-C 12 Alkyl, C1-C 12 Alkoxy, C3-C 16 cycloalkyl, C6-C 16 Aryl, C2-C 12 Epoxy groups; m, n, o, p, q and r are each an independent integer from 1 to 12.

[0014] According to another embodiment of the first aspect of this application, the mass ratio of the compound shown in Formula I to the compound shown in Formula II is 8:2 to 2:8.

[0015] According to another embodiment of the first aspect of this application, the first epoxy compound includes a compound represented by Formula Ia, a compound represented by Formula IIa, or simultaneously includes a compound represented by both Formula Ia and Formula IIa:

[0016]

[0017] According to another embodiment of the first aspect of this application, the mass ratio of the compound shown in Formula Ia to the compound shown in Formula IIa is 8:2 to 2:8.

[0018] According to another embodiment of the first aspect of this application, the second epoxy compound comprises at least one structure having the structure shown in Formula III:

[0019]

[0020] Where R 13 R 14 R 15 R 16 R 17 R 18 and R 19 Each is independently selected from hydrogen, C1-C 12 Alkyl, C1-C 12 Alkoxy, C3-C 16 cycloalkyl, C6-C 16 Aryl, C2-C 12 Epoxy group; s is an integer from 1 to 12.

[0021] According to another embodiment of the first aspect of this application, the epoxy resin is selected from at least one of the following: phenolic epoxy resin, naphthyl difunctional epoxy resin, and naphthyl trifunctional epoxy resin.

[0022] According to another embodiment of the first aspect of this application, the first curing agent is selected from at least one of the following: dimethylthiotoluene diamine (DMTDA), diethyltoluene diamine (DETDA), and 4,4'-bis-sec-butylaminodiphenylmethane (MDBA).

[0023] According to another embodiment of the first aspect of this application, the second curing agent is selected from at least one of the following: diaminodiphenyl sulfone (DDS) and dicyandiamide.

[0024] According to another embodiment of the first aspect of this application, the accelerator is selected from at least one of the following: imidazole accelerators, tertiary amines, and boron trifluoride monoethylamine.

[0025] According to another embodiment of the first aspect of this application, the total mass of the epoxy prepolymer is 100% by mass, wherein the content of the first epoxy compound is 60-80% by mass, the content of the second epoxy compound is 4-10% by mass, and the content of the first curing agent is 20-30% by mass.

[0026] According to another embodiment of the first aspect of this application, with the total mass of the epoxy resin composition being 100% by mass, the content of component A is 30-50% by mass, the content of component B is 20-50% by mass, the content of component C is 10-35% by mass, and the content of component D is 2-5%.

[0027] A second aspect of this application provides a method for synthesizing epoxy prepreg, the method using the epoxy resin composition of this application, the method comprising the following steps:

[0028] Step 1: The first epoxy compound, optionally the second epoxy compound, and the first curing agent undergo a polymerization reaction to generate the epoxy prepolymer;

[0029] Step 2: The epoxy prepolymer, epoxy resin, second curing agent, and accelerator undergo a polymerization reaction to generate the epoxy prepreg;

[0030] The method does not use thermoplastic resin toughening agents.

[0031] According to another embodiment of the second aspect of this application, the second epoxy compound undergoes a prepolymerization reaction with the first curing agent to generate a precursor prepolymer, and then the precursor prepolymer undergoes a polymerization reaction with the first epoxy compound to generate the epoxy prepolymer.

[0032] A third aspect of this application provides an epoxy prepreg prepared by the method of this application.

[0033] A fourth aspect of this application provides an epoxy resin product made using the epoxy prepreg of this application, the epoxy resin product comprising: a film, a fiber-reinforced epoxy resin composite product. Detailed Implementation

[0034] The “range” disclosed in this document takes the form of a lower limit and an upper limit. It can be one or more lower limits and one or more upper limits, respectively. A given range is defined by selecting a lower limit and an upper limit. The selected lower and upper limits define the boundaries of the particular range. All ranges that can be defined in this way are inclusive and composable; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is also expected that ranges of 60-110 and 80-120 are also included. Furthermore, if the minimum range values ​​are listed as 1 and 2, and if the maximum range values ​​are listed as 3, 4, and 5, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5.

[0035] In this application, unless otherwise stated, the numerical range "ab" is a shortened representation of any combination of real numbers from a to b, where a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been listed in this document, and "0-5" is simply a shortened representation of these numerical combinations.

[0036] Unless otherwise specified in this application, all embodiments and preferred embodiments mentioned herein can be combined to form new technical solutions.

[0037] Unless otherwise specified, all technical features and preferred features mentioned herein can be combined to form new technical solutions.

[0038] In this application, unless otherwise specified, the term "comprising" as used herein can be either open-ended or closed-ended. For example, "comprising" may mean that it may also include other components not listed, or it may only include the listed components.

[0039] The inventive point of this application is based on a specially designed combination of raw materials for preparing epoxy prepregs. In this application, the specially designed combination of raw materials is referred to as an "epoxy resin composition". The combination of raw materials includes specially designed raw materials, and the raw material formulation excludes thermoplastic resin toughening agents. While avoiding the defects of poor compatibility and performance degradation caused by thermoplastic resin toughening agents, the resulting epoxy prepregs and final products have excellent performance.

[0040] The epoxy resin composition of this application comprises:

[0041] Component A: Epoxy prepolymer, which is prepared from raw materials including: a first epoxy compound, an optional second epoxy compound and a first curing agent, wherein the first epoxy compound is an aromatic compound containing at least three epoxy groups, the second epoxy compound includes at least one epoxy compound different from the first epoxy compound, and the first curing agent is a liquid aromatic amine;

[0042] Component B: Epoxy resin, the composition of which differs from that of the prepolymer;

[0043] Component C: Second curing agent; and

[0044] Component D: Accelerator;

[0045] The epoxy resin composition does not contain thermoplastic resin toughening agents.

[0046] According to one embodiment of this application, the first epoxy compound is an aromatic compound containing three epoxy groups, and more specifically, an aromatic compound containing at least one nitrogen atom and three epoxy groups. According to a specific embodiment of this application, the first epoxy compound includes a compound of Formula I, or a compound of Formula II, or both Formula I and Formula II. In the case where the first epoxy compound includes both Formula I and Formula II, the mass ratio of the compound of Formula I to the compound of Formula II is 8:2 to 2:8. For example, the mass ratio of the compound of Formula I to the compound of Formula II can be 7:3 to 3:7, or 6:4 to 4:6, or 7:3 to 5:5, or 6:4 to 5:5, or the mass ratio can be within the range obtained by combining any two of the above end values.

[0047]

[0048] According to one embodiment of this application, in formulas I and II above, R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 R 11 and R 12 Each is independently selected from: hydrogen, C1-C 12 Alkyl, C1-C 12 Alkoxy, C3-C 16 cycloalkyl, C6-C 16 Aryl, C2-C 12 Epoxy groups; for example, each can be independently selected from: hydrogen, C1-C 10 Alkyl, C1-C 10 Alkoxy, C3-C 14 cycloalkyl, C6-C 14 Aryl, C2-C 10 Epoxy groups; or may be independently selected from hydrogen, C1-C8 alkyl, C1-C8 alkoxy, C3-C 12 cycloalkyl, C6-C 12 Aryl, C2-C8 epoxy; or each can be independently selected from hydrogen, C1-C6 alkyl, C1-C6 alkoxy, C3-C6 cycloalkyl, C6-C 10 Aryl, C2-C6 epoxy; or each can be independently selected from hydrogen, C1-C4 alkyl, C1-C4 alkoxy, C3-C4 cycloalkyl, C6-C 10 Aryl, C2-C6 epoxy; or each can be independently selected from hydrogen, C1-C3 alkyl, C1-C3 alkoxy, C3-C6 cycloalkyl, C6-C8 aryl, C2-C3 epoxy.

[0049] According to one embodiment of this application, in Formula I and Formula II, m, n, o, p, q and r are each independently an integer from 1 to 12, for example, each can be an integer 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12.

[0050] According to one specific embodiment of this application, the first epoxy compound is a compound represented by Formula Ia, with the chemical name triglycidyl-m-aminophenol, also known as m-(2,3-epoxy-propoxy)-N,N-bis(2,3-epoxypropyl)aniline; or a compound represented by Formula IIa, with the chemical name triglycidyl-p-aminophenol, also known as p-(2,3-epoxy-propoxy)-N,N-bis(2,3-epoxypropyl)aniline; or it may be a combination of the compound represented by Formula Ia and the compound represented by Formula IIa. For the first epoxy compound including a combination of compounds of formula Ia and compounds of formula IIa, wherein the mass ratio of the compound of formula Ia to the compound of formula IIa is 8:2 to 2:8, for example, the mass ratio of the compound of formula Ia to the compound of formula IIa can be 7:3 to 3:7, for example, the mass ratio of the compound of formula Ia to the compound of formula IIa can be 7:3 to 4:6, or the mass ratio can be 7:3 to 5:5, or the mass ratio can be 6:4 to 5:5, or the mass ratio of the two can be within the numerical range obtained by combining any two of the above end values.

[0051]

[0052] According to some embodiments of this application, the triglycidyl-m-aminophenol and triglycidyl-p-aminophenol are commercially available. For example, triglycidyl-m-aminophenol can be commercially available as AFG-90M, while triglycidyl-p-aminophenol can be commercially available as AFG-90.

[0053] According to another embodiment of this application, the second epoxy compound used to synthesize the prepolymer is an epoxy compound different from the first epoxy monomer. For example, the second epoxy compound may be an aromatic monomer containing an epoxy group. According to one embodiment of this application, the second epoxy compound has the structure shown in Formula III:

[0054]

[0055] Where R 13 R 14 R 15 R 16 R 17 R 18 and R 19 Each is independently selected from hydrogen, C1-C12 Alkyl, C1-C 12 Alkoxy, C3-C 16 cycloalkyl, C6-C 16 Aryl, C2-C 12 Epoxy groups; for example, each can be independently selected from: hydrogen, C1-C 10 Alkyl, C1-C 10 Alkoxy, C3-C 14 cycloalkyl, C6-C 14 Aryl, C2-C 10 Epoxy groups; or may be independently selected from hydrogen, C1-C8 alkyl, C1-C8 alkoxy, C3-C 12 cycloalkyl, C6-C 12 Aryl, C2-C8 epoxy; or each can be independently selected from hydrogen, C1-C6 alkyl, C1-C6 alkoxy, C3-C6 cycloalkyl, C6-C 10 Aryl, C2-C6 epoxy; or each can be independently selected from hydrogen, C1-C4 alkyl, C1-C4 alkoxy, C3-C4 cycloalkyl, C6-C 10 Aryl, C2-C6 epoxy; or each can be independently selected from hydrogen, C1-C3 alkyl, C1-C3 alkoxy, C3-C6 cycloalkyl, C6-C8 aryl, C2-C3 epoxy. According to another embodiment of this application, s is an integer from 1 to 12, for example, s can be an integer 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12.

[0056] According to a specific embodiment of this application, the second epoxy compound may be a compound represented by Formula III, wherein R 13 R 14 R 15 R 16 R 17 R 18 and R 19 All atoms are hydrogen atoms, and s is an integer 1. In this case, the compound is called "phenyl glycidyl ether" and can be commercially available under the trade name phenyl glycidyl ether.

[0057] According to one embodiment of this application, the first curing agent is selected from at least one of the following: dimethylthiotoluene diamine (DMTDA), diethyltoluene diamine (DETDA), and 4,4'-bis-sec-butylaminodiphenylmethane (MDBA).

[0058] According to one embodiment of this application, in the first step of the method of this application, the epoxy prepolymer is prepared by causing the first epoxy compound, optionally a second epoxy compound and a first curing agent to undergo a polymerization reaction to generate the epoxy prepolymer.

[0059] According to a specific embodiment of this application, in the first step of the method, the second epoxy compound undergoes a prepolymerization reaction with a first curing agent to generate a precursor prepolymer. Then, the precursor prepolymer undergoes a polymerization reaction with the first epoxy compound to generate the epoxy prepolymer. That is, in this specific embodiment, the second epoxy compound first undergoes a preliminary prepolymerization reaction with a liquid aromatic amine curing agent (the first curing agent) to obtain an amine-functionalized end-capped amino prepolymer (referred to as a "precursor prepolymer" or "preliminary prepolymer" in this invention); then, it further reacts with the first epoxy compound to prepolymerize, obtaining the final epoxy prepolymer.

[0060] According to one embodiment of this application, the prepolymerization reaction can be carried out in an air atmosphere or an inert atmosphere, such as a nitrogen atmosphere. According to another embodiment of this application, the reaction temperature of the prepolymerization reaction can be 30-100°C, for example 40-90°C, or 50-80°C, or 60-70°C, or the temperature can be within a numerical range obtained by combining any two of the above extreme values. The duration of the prepolymerization reaction can be 0.5-24 hours, for example 1-20 hours, or 2-16 hours, or 3-12 hours, or 4-8 hours, or 4-6 hours, or the reaction duration can be within a numerical range obtained by combining any two of the above extreme values.

[0061] According to another embodiment of this application, the first step of the prepolymerization reaction includes two sub-steps. In the first sub-step, the second epoxy compound reacts with the first curing agent to form a precursor prepolymer. In the second sub-step, the precursor prepolymer reacts with the first epoxy compound to form the epoxy prepolymer. The first sub-step can be carried out in an air atmosphere or an inert atmosphere, such as a nitrogen atmosphere. The reaction temperature of the first sub-step can be 30-100°C, for example, 40-90°C, or 50-80°C, or 60-70°C, or the temperature can be within a numerical range obtained by combining any two of the above extreme values. The reaction duration of the first sub-step can be 0.5-24 hours, for example, 1-20 hours, or 1.5-16 hours, or 2-12 hours, or 2-8 hours, or 2-4 hours, or the reaction duration can be within a numerical range obtained by combining any two of the above extreme values. The second sub-step can be carried out in an air atmosphere or an inert atmosphere, such as a nitrogen atmosphere. The reaction temperature of the second sub-step can be 40-100℃, for example 50-90℃, or 60-80℃, or 70-80℃, or the temperature can be within the range of any combination of the above two extreme values. The reaction duration of the second sub-step can be 0.5-24 hours, for example 1-20 hours, or 1.5-16 hours, or 2-12 hours, or 2-8 hours, or 2-4 hours, or the reaction duration can be within the range of any combination of the above two extreme values.

[0062] According to one embodiment of this application, the prepolymer prepared in step one can be characterized by epoxy value and viscosity. The epoxy value represents the amount of epoxy groups contained in 100g of epoxy resin, and can be detected using standard methods known in the art, such as the hydrochloric acid-acetone method, to detect the epoxy value of the prepolymer and the epoxy resin prepared in subsequent steps.

[0063] According to one embodiment of this application, the epoxy value of the prepolymer can be 0.50-0.70 mol / 100g, for example 0.52-0.69 mol / 100g, or 0.55-0.68 mol / 100g, or 0.58-0.67 mol / 100g, or 0.60-0.67 mol / 100g, or 0.63-0.67 mol / 100g, or can be within the range of values ​​obtained by combining any two of the above end values.

[0064] According to another embodiment of this application, the viscosity of the prepolymer and the epoxy resin prepared in subsequent steps can be tested using known standard methods, such as GB / T22314-2008. According to one embodiment of this application, the viscosity of the prepolymer obtained in step one (measured at 40°C) can be 2000-8000 mPa·s, for example, 2500-7000 mPa·s, or 3000-6000 mPa·s, or 4000-5000 mPa·s, or 4800-5800 mPa·s, or within a range obtained by combining any two of the above values.

[0065] According to one embodiment of this application, the amounts of the first epoxy compound, the second epoxy compound, and the first curing agent used in step one satisfy the following settings: Based on the total mass of the epoxy prepolymer (i.e., the total mass of all raw materials used to prepare the epoxy prepolymer) as 100% by mass, the content of the first epoxy compound is 60-80% by mass, the content of the second epoxy compound is 4-10% by mass, and the content of the first curing agent is 20-30% by mass; according to one embodiment of this application, the content of the first epoxy compound is 62-78% by mass, or it can be 64-76% by mass, or it can be 65-75% by mass, or it can be 66-74% by mass, or it can be 67-73% by mass, or it can be 68-72% by mass, or it can be 69-71% by mass. The content of the second epoxy compound is 4-10% by mass, or 5-9% by mass, or 6-8% by mass, or 6-7% by mass, or within the range of values ​​obtained by combining any two of the above-mentioned endpoints; according to another embodiment of this application, the content of the first curing agent is 20-30% by mass, or 21-29% by mass, or 22-28% by mass, or 23-27% by mass, or 24-26% by mass, or 25-26% by mass, or within the range of values ​​obtained by combining any two of the above-mentioned endpoints.

[0066] According to one embodiment of this application, in step two, the epoxy prepolymer, epoxy resin, second curing agent and accelerator undergo a polymerization reaction to generate the epoxy prepreg of the present invention.

[0067] According to one embodiment of this application, the epoxy resin is selected from at least one of the following: phenolic epoxy resin, naphthyl difunctional epoxy resin, and naphthyl trifunctional epoxy resin. According to another embodiment of this application, the second curing agent is selected from at least one of the following: diaminodiphenyl sulfone (DDS) and dicyandiamide. According to another embodiment of this application, the accelerator is selected from at least one of the following: imidazole accelerators, tertiary amine accelerators, and boron trifluoride monoethylamine.

[0068] According to one embodiment of this application, based on the total mass of all raw materials used in step two as 100% by mass, the content of component A (the prepolymer obtained in step one) is 30-50% by mass, the content of component B (epoxy resin) is 20-50% by mass, the content of component C (second curing agent) is 10-35% by mass, and the content of component D (accelerator) is 2-5%. According to another embodiment of this application, the content of component A is 30-50% by mass, or it can be 32-48% by mass, or it can be 35-45% by mass, or it can be 38-42% by mass, or it can be 40-41% by mass, or it can be within the range of values ​​obtained by combining any two of the above endpoints. According to another embodiment of this application, the content of component B is 20-50% by mass, or it can be 22-45% by mass, or it can be 25-42% by mass, or it can be 28-40% by mass, or it can be 30-38% by mass, or it can be 32-35% by mass, or it can be within the range of values ​​obtained by combining any two of the above endpoints. According to another embodiment of this application, the content of component C is 10-35% by mass, or 12-32% by mass, or 15-30% by mass, or 18-28% by mass, or 20-25% by mass, or within the range of any combination of the above two endpoints. According to another embodiment of this application, the content of component D is 2-5% by mass, or 3-4% by mass, or within the range of any combination of the above two endpoints.

[0069] According to another embodiment of this application, the viscosity of the prepreg obtained in step two (measured at 70°C) can be 50-150 Pa·S, for example, 60-130 Pa·S, or 70-120 Pa·S, or 80-110 Pa·S, or 90-100 Pa·S, or 70-100 Pa·S, or within the range of values ​​obtained by combining any two of the above endpoints.

[0070] According to one embodiment of this application, no thermoplastic resin toughening agent is used in the compositions and methods of the present invention. For example, the thermoplastic resin toughening agent includes one or more of the following, or all of the following thermoplastic resin toughening agents: polysulfone, polyethersulfone, polyarylethersulfone, and polyetherketone.

[0071] According to one embodiment of this application, products can be prepared using the prepreg of this application, the products including films or fiber-reinforced composite products, the fibers including carbon fibers. For example, carbon fibers can be mixed with the prepreg in a specific ratio as needed, and then the mixture can be manufactured into the desired form or shape using various molding methods. For example, the molding methods may include casting, extrusion, casting, rolling, etc.

[0072] This invention, through the use of a specially designed prepreg formulation, produces epoxy prepolymers, prepregs, and products that retain the characteristics of high temperature resistance and high performance. Furthermore, it eliminates the need for thermoplastic resin toughening agents, significantly improving high-temperature solubility, compatibility, and viscosity properties, simplifying the production process, and reducing production energy consumption and costs.

[0073] The present application is described below by way of specific embodiments, the purpose of which is to provide a better understanding of the content of the present application. It should be understood that these embodiments are merely illustrative and not restrictive. The reagents used in the embodiments, unless otherwise stated, are commercially available. The methods and conditions used in the embodiments, unless otherwise specified, are conventional methods and conditions.

[0074] Example

[0075] In the following embodiments, various properties of the samples were tested using the following techniques:

[0076] (1) Tg test

[0077] Differential scanning calorimetry (DSC) was used to perform temperature scanning on the samples. The scanning range was 40–260 °C, the heating rate was 10 °C / min, and high-purity nitrogen was used for protection throughout the process. The sample volume was controlled at 5–10 mg and placed in an aluminum crucible for testing.

[0078] (2) Viscosity test

[0079] The viscosity of each group of samples was tested using a cone-plate viscometer, with a temperature range of 25℃-60℃.

[0080] (3) Mechanical property testing

[0081] The tensile and bending properties of epoxy castings were tested using a universal testing machine according to the GB / T2567-2008 standard.

[0082] The AFG90, AFG-90M, and AG-80 used in the following examples were self-produced; 638S was a phenolic epoxy resin purchased from Kunshan Nanya; phenyl glycidyl ether XY690 was purchased from Anhui Xinyuan; DETDA was purchased from Zhangjiagang Yarui; PN-23 was purchased from Ajinomoto, Japan; and DDS was purchased from Guangzhou Qian'an Chemical.

[0083] Example 1

[0084] (1) Preparation of epoxy prepolymer: 200 g of DETDA was added to a 500 ml glass flask, nitrogen gas was introduced, and the temperature was raised to 60 °C. 40 g of phenyl glycidyl ether was added in three batches, and the reaction was carried out at 60 °C for 2 h to obtain an amino-terminated prepolymer. 600 g of p-aminophenol trifunctional epoxy resin AFG-90 was added to a 2 L three-necked glass flask, and the temperature was raised to 80 °C. Nitrogen gas was introduced, and 240 g of the amino-terminated prepolymer obtained in the first step was added to the flask in batches. The reaction was carried out at 80 °C for 2 h to obtain the final epoxy prepolymer A1. The epoxy value of the epoxy prepolymer was tested: eq = 0.65 mol / 100 g, and the viscosity at 40 °C was 5800 mPa·s.

[0085] (2) Preparation of epoxy prepreg resin: Take 40g of the epoxy prepolymer A1 prepared above and add it to a glass flask. Heat the flask to 70℃, add 30g of phenolic epoxy resin 638S, stir for 30min, then add 28g of DDS, stir for 30min, add 2g of accelerator PN-23, stir for 10min, and discharge to obtain epoxy prepreg resin F1. The viscosity at 70℃ is 100Pa.S, and the viscosity at room temperature is grade 1, which meets the requirements of the prepreg molding process.

[0086] (3) Preparation of epoxy castings: The epoxy prepreg resin F1 prepared above was added into a glass mold and placed in an oven for curing at 120℃ for 3 hours + 180℃ for 3 hours. The resulting epoxy castings were cut into tensile, bending, and DMA specimens, and the test results are shown in Table 1 below.

[0087] Table 1 Mechanical property data of epoxy prepreg resin

[0088] Tensile strength (MPa) 83 Elongation at break % 5.8 Flexural strength MPa 153 Tg (°C, DSC) 188

[0089] Example 2

[0090] (1) Preparation of epoxy prepolymer: 200 g of DETDA was added to a 500 ml three-necked glass flask, nitrogen gas was introduced, and the temperature was raised to 60 °C. 40 g of phenyl glycidyl ether was added in three batches, and the reaction was carried out at 60 °C for 2 h to obtain an amino-terminated prepolymer. 600 g of m-aminophenol trifunctional epoxy resin AFG-90M was added to a 2 L three-necked glass flask, and the temperature was raised to 80 °C. Nitrogen gas was introduced, and 240 g of the amino-terminated prepolymer obtained in the first step was added to the flask in batches. The reaction was carried out at 80 °C for 2 h to obtain the final epoxy prepolymer A1. The epoxy value of the epoxy prepolymer was tested: eq = 0.61 mol / 100 g, and the viscosity at 40 °C was 5635 mPa·s.

[0091] (2) Preparation of epoxy prepreg resin: Take 50g of the epoxy prepolymer A1 prepared above and add it to a glass flask. Heat the flask to 70℃, add 30g of phenolic epoxy resin 638S, stir for 30min, then add 28g of DDS, stir for 30min, add 2g of accelerator PN-23, stir for 10min, and discharge to obtain epoxy prepreg resin F2. The viscosity at 70℃ is 93Pa.S, and the viscosity grade is 1 at room temperature, which meets the requirements of the prepreg molding process.

[0092] (3) Preparation of epoxy castings: The epoxy prepreg resin F2 prepared above was added into a glass mold and placed in an oven for curing at 120℃ for 3 hours + 180℃ for 3 hours. The resulting epoxy castings were cut into tensile, bending, and DMA specimens, and the test results are shown in Table 2 below.

[0093] Table 2 Mechanical property data of epoxy prepreg resin

[0094] Tensile strength (MPa) 88 Elongation at break % 6.3 Flexural strength MPa 158 Tg (°C, DSC) 186

[0095] Example 3

[0096] (1) Preparation of epoxy prepolymer: 200 g of DETDA was added to a 500 ml three-necked glass flask, nitrogen gas was introduced, and the temperature was raised to 60 °C. 40 g of phenyl glycidyl ether was added in three batches, and the mixture was reacted at 60 °C for 2 h to obtain an amino-terminated prepolymer. 420 g of p-aminophenol trifunctional epoxy resin AFG-90 and 180 g of m-aminophenol trifunctional epoxy resin AFG-90M were added to a 2 L three-necked glass flask, and the temperature was raised to 80 °C. Nitrogen gas was introduced, and 260 g of the amino-terminated prepolymer obtained in the first step was added to the flask in batches. The mixture was reacted at 80 °C for 2 h to obtain the final epoxy prepolymer A2. The epoxy value of the epoxy prepolymer was tested as follows: eq = 0.63 mol / 100 g, viscosity at 40 °C 5710 mPa·s.

[0097] (2) Preparation of epoxy prepreg resin: Take 40g of the epoxy prepolymer A2 prepared above and add it to a glass flask. Heat to 70℃, add 30g of phenolic epoxy resin 638S, stir for 30min, then add 28g of DDS and stir for 10min. Add 2g of accelerator PN-23 and discharge to obtain epoxy prepreg resin F3. The viscosity at 70℃ is 96Pa.S and the viscosity grade is 1 at room temperature, which meets the requirements of the prepreg molding process.

[0098] (3) Preparation of epoxy casting: The epoxy prepreg resin F3 prepared above was added into a glass mold and placed in an oven to cure at 120℃ for 3h + 180℃ for 3h. The epoxy casting was cut into tensile, bending and DMA specimens and the test results are shown in Table 3 below.

[0099] Table 3 Mechanical property data of epoxy prepreg resin

[0100] Tensile strength (MPa) 90 Elongation at break % 6.6 Flexural strength MPa 160 Tg (°C, DSC) 188

[0101] Example 4

[0102] (1) Preparation of epoxy prepolymer: 200 g of DETDA was added to a 500 ml three-necked glass flask, nitrogen gas was introduced, and the temperature was raised to 60 °C. 40 g of phenyl glycidyl ether was added in three batches, and the mixture was reacted at 60 °C for 2 h to obtain an amino-terminated prepolymer. 300 g of p-aminophenol trifunctional epoxy resin AFG-90 and 300 g of m-aminophenol trifunctional epoxy resin AFG-90M were added to a 2 L three-necked glass flask, and the temperature was raised to 80 °C. Nitrogen gas was introduced, and 240 g of the amino-terminated prepolymer obtained in the first step was added to the flask in batches. The mixture was reacted at 80 °C for 2 h to obtain the final epoxy prepolymer A1. The epoxy value of the epoxy prepolymer was tested as follows: eq = 0.62 mol / 100 g, viscosity at 40 °C 5600 mPa·s.

[0103] (2) Preparation of epoxy prepreg resin: Take 50g of the epoxy prepolymer A1 prepared above and add it to a glass flask. Heat the flask to 70℃, add 30g of phenolic epoxy resin 638S, stir for 30min, then add 28g of DDS, stir for 30min, add 2g of accelerator PN-23, stir for 10min, and discharge to obtain epoxy prepreg resin F4. The viscosity at 70℃ is 93Pa.S, and the viscosity grade is 1 at room temperature, which meets the requirements of the prepreg molding process.

[0104] (3) Preparation of epoxy castings: The epoxy prepreg resin F4 prepared above was added into a glass mold and placed in an oven for curing at 120℃ for 3 hours + 160℃ for 3 hours. The resulting epoxy castings were cut into tensile, bending, and DMA specimens, and the test results are shown in Table 4 below.

[0105] Table 4 Mechanical property data of epoxy prepreg resin

[0106] Tensile strength (MPa) 92 Elongation at break % 7.1 Flexural strength MPa 161 Tg (°C, DSC) 187

[0107] Example 5

[0108] (1) Preparation of epoxy prepolymer: 200 g of DETDA was added to a 500 ml three-necked glass flask, nitrogen gas was introduced, and the temperature was raised to 60 °C. 40 g of phenyl glycidyl ether was added in three batches, and the mixture was reacted at 60 °C for 2 h to obtain an amino-terminated prepolymer. 360 g of p-aminophenol trifunctional epoxy resin AFG-90 and 240 g of m-aminophenol trifunctional epoxy resin AFG-90M were added to a 2 L three-necked glass flask, and the temperature was raised to 80 °C. Nitrogen gas was introduced, and 240 g of the amino-terminated prepolymer obtained in the first step was added to the flask in batches. The mixture was reacted at 80 °C for 2 h to obtain the final epoxy prepolymer A1. The epoxy value of the epoxy prepolymer was tested as follows: eq = 0.63 mol / 100 g, viscosity at 40 °C 5610 mPa·s.

[0109] (2) Preparation of epoxy prepreg resin: Take 50g of the epoxy prepolymer A1 prepared above and add it to a glass flask. Heat the flask to 70℃, add 30g of phenolic epoxy resin 638S, stir for 30min, then add 28g of DDS, stir for 30min, add 2g of accelerator PN-23, stir for 10min, and discharge to obtain epoxy prepreg resin F4. The viscosity at 70℃ is 92Pa.S, and the viscosity grade is 1 at room temperature, which meets the requirements of the prepreg molding process.

[0110] (3) Preparation of epoxy castings: The epoxy prepreg resin F4 prepared above was added into a glass mold and placed in an oven for curing at 120℃ for 3 hours + 160℃ for 3 hours. The resulting epoxy castings were cut into tensile, bending, and DMA specimens, and the test results are shown in Table 5 below.

[0111] Table 5 Mechanical property data of epoxy prepreg resin

[0112] Tensile strength (MPa) 95 Elongation at break % 7.3 Flexural strength MPa 168 Tg((℃,DSC)) 187

[0113] Comparative Example

[0114] (1) Preparation of epoxy prepolymer: 200 g of DETDA was added to a 500 ml three-necked glass flask, nitrogen gas was introduced, and the temperature was raised to 60 °C. 40 g of phenyl glycidyl ether was added in three batches, and the reaction was carried out at 60 °C for 2 h to obtain an amino-terminated prepolymer. 600 g of amino tetrafunctional epoxy resin AG-80 was added to a 2 L three-necked glass flask, and the temperature was raised to 70 °C. Nitrogen gas was introduced, and 240 g of the amino-terminated prepolymer obtained in the first step was added to the flask in batches. The reaction was carried out at 70 °C for 2 h to obtain the final epoxy prepolymer A1. The epoxy value of the epoxy prepolymer was tested: eq = 0.59 mol / 100 g, and the viscosity at 40 °C was 7800 mPa·s.

[0115] (2) Preparation of epoxy prepreg resin: Take 50g of the epoxy prepolymer A1 prepared above and add it to a glass flask. Heat to 70℃, add 30g of phenolic epoxy resin 638S, stir for 30min, then add 27g of DDS, stir for 30min, add 2g of accelerator PN-23, stir for 10min, and discharge to obtain epoxy prepreg resin F4. The viscosity at 70℃ is 120Pa.S, and the viscosity at room temperature is grade 1, which meets the requirements of the prepreg molding process.

[0116] (3) Preparation of epoxy castings: The epoxy prepreg resin F4 prepared above was added into a glass mold and placed in an oven for curing at 120℃ for 3 hours + 180℃ for 3 hours. The resulting epoxy castings were cut into tensile, bending, and DMA specimens, and the test results are shown in Table 6 below.

[0117] Table 6 Mechanical Properties of Epoxy Prepreg Resins

[0118] Tensile strength (MPa) 76 Elongation at break % 4.5 Flexural strength MPa 145 Tg((℃,DSC)) 193

Claims

1. An epoxy resin composition comprising: Component A: Epoxy prepolymer, which is prepared from raw materials comprising: a first epoxy compound, optionally a second epoxy compound, and a first curing agent, wherein the first epoxy compound is an aromatic compound containing at least three epoxy groups, the second epoxy compound comprises at least one epoxy compound different from the first epoxy compound, and the first curing agent is a liquid aromatic amine; wherein the total mass of the epoxy prepolymer is 100% by mass, the content of the first epoxy compound is 60-80% by mass, the content of the second epoxy compound is 4-10% by mass, and the content of the first curing agent is 20-30% by mass; The first epoxy compound includes at least one compound represented by Formula I and Formula II. In equations I and II above, R1, R2, R3, R4, R5, R6, R7, R8, R9, R 10 R 11 and R 12 Each is independently selected from: hydrogen, C1-C 12 Alkyl, C1-C 12 Alkoxy, C3-C 16 cycloalkyl, C6-C 16 Aryl, C2-C 12 Epoxy groups; m, n, o, p, q, and r are each an independent integer from 1 to 12; The second epoxy compound includes at least one structure having the structure shown in Formula III: Where R 13 R 14 R 15 R 16 R 17 R 18 and R 19 Each is independently selected from hydrogen, C1-C 12 Alkyl, C1-C 12 Alkoxy, C3-C 16 cycloalkyl, C6-C 16 Aryl, C2-C 12 Epoxy group; s is an integer from 1 to 12; The first curing agent is selected from at least one of the following: dimethyl thiotoluene diamine (DMTDA), diethyltoluene diamine (DETDA), and 4,4'-bis-sec-butylaminodiphenylmethane (MDBA); Component B: Epoxy resin, wherein the composition of the epoxy resin is different from that of the prepolymer, and the epoxy resin is selected from at least one of the following: phenolic epoxy resin, naphthyl difunctional epoxy resin, and naphthyl trifunctional epoxy resin. Component C: Second curing agent, wherein the second curing agent is selected from at least one of the following: diaminodiphenyl sulfone (DDS), dicyandiamide; and Component D: Accelerator, wherein the accelerator is selected from at least one of the following: imidazole accelerators, tertiary amines, and boron trifluoride monoethylamine; With the total mass of the epoxy resin composition being 100%, the content of component A is 30-50%, the content of component B is 20-50% by mass, the content of component C is 10-35%, and the content of component D is 2-5%. The epoxy resin composition does not contain thermoplastic resin toughening agents.

2. The epoxy resin composition according to claim 1, characterized in that, The first epoxy compound includes compounds represented by Formula I and Formula II. Furthermore, the mass ratio of the compound shown in Formula I to the compound shown in Formula II is 8:2 to 2:

8.

3. The epoxy resin composition according to claim 1, characterized in that, The first epoxy compound includes at least one of the compounds shown in Formula Ia and Formula IIa.

4. The epoxy resin composition according to claim 3, characterized in that, The first epoxy compound includes compounds represented by formula Ia and compounds represented by formula IIa. Furthermore, the mass ratio of the compound shown in Formula Ia to the compound shown in Formula IIa is 8:2 to 2:

8.

5. A method for synthesizing epoxy prepreg, the method using an epoxy resin composition as described in any one of claims 1-4, the method comprising the following steps: Step 1: The first epoxy compound, optionally the second epoxy compound, and the first curing agent undergo a polymerization reaction to generate the epoxy prepolymer; Step 2: The epoxy prepolymer, epoxy resin, second curing agent, and accelerator undergo a polymerization reaction to generate the epoxy prepreg; The method does not use thermoplastic resin toughening agents.

6. The method as described in claim 5, characterized in that, The second epoxy compound undergoes a prepolymerization reaction with the first curing agent to generate a precursor prepolymer, which then undergoes a polymerization reaction with the first epoxy compound to generate the epoxy prepolymer.

7. An epoxy prepreg prepared by the method of claim 5 or 6.

8. An epoxy resin product, the product being prepared using the epoxy prepreg of claim 7, the epoxy resin product comprising: Adhesive film and fiber-reinforced epoxy resin composite products.

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