An epoxy resin composition, a method of preparation and use

Abstract

The application relates to an epoxy resin composition, a preparation method and application. In order to solve the unreasonable problem of the processing period of the existing epoxy resin composition for preparing prepreg, the epoxy resin composition is composed of component A and component B; the component A is composed of liquid epoxy resin I and solid epoxy resin; the component B is composed of liquid epoxy resin II, a curing agent and an accelerator; the preparation method is as follows: the solid epoxy resin is melted by heating, the liquid epoxy resin I is added, the component A is obtained after uniform stirring; the liquid epoxy resin II, the curing agent and the accelerator are mixed and ground, the component B is obtained after uniform heating mixing; the component A and the component B are uniformly stirred and mixed at 55-85 DEG C. The resin composition has good processability and coating property, the prepreg composite material prepared by using the resin composition shows excellent mechanical property and heat resistance, is suitable for engineering fields such as automobiles, and meets the requirements of light weight and high strength.

Description

Technical Field

[0001] This invention relates to an epoxy resin, its preparation method, and its application. Background Technology

[0002] In the engineering field, lightweighting is a common challenge, whether for large spacecraft or tiny mechanical parts. The car body, as a key load-bearing component, directly impacts passenger safety. Meanwhile, the introduction of energy-saving and emission-reduction regulations for automobiles further emphasizes the importance of lightweight car body design. Utilizing lightweight, high-strength materials has become a crucial strategy for lightweighting car bodies. Carbon fiber composites, as a representative of lightweight materials, are a strong candidate material due to their excellent properties such as low density, high specific strength, high specific modulus, fatigue resistance, corrosion resistance, and outstanding thermal and chemical stability.

[0003] Prepreg is a material prepared by continuously impregnating reinforcing fibers or fiber fabrics with a precisely controlled resin matrix and then processing it to achieve a certain shelf life at room temperature. Pre-impregnation of the resin significantly reduces the processing steps in the final product manufacturing process, resulting in a high degree of automation and enabling the one-time molding of complex shapes, thus offering broad application prospects. Carbon fiber, due to its superior mechanical properties and stability, is gradually replacing traditional glass fiber as the primary prepreg reinforcement.

[0004] Hot melt prepregs require the resin system to have a low viscosity when melting at high temperatures, and a sufficiently long processing time is needed to fully impregnate the fibers; and the resin system in hot melt prepregs needs to have a certain viscosity to prevent glue flow during storage or transportation at room temperature.

[0005] Therefore, how to create a new epoxy resin composition, prepreg and its preparation method, and extend the processing time of the epoxy resin matrix to meet both the requirements of continuous production and the requirement that the product has good mechanical properties after resin curing, has become a key improvement goal that urgently needs to be solved in the industry.

[0006] In existing technologies, epoxy resin compositions often exhibit high viscosity and rapid viscosity increase during high-temperature melting, resulting in a short processing time and hindering complete fiber impregnation. This leads to undesirable impregnation phenomena such as pitting, dry yarn, and twisting, affecting the overall performance of the prepreg. Furthermore, the low viscosity at room temperature results in resin flow and poor dimensional stability. The prepreg prepared in this way exhibits significant bending and deformation after the release paper is peeled off, which is detrimental to storage and transportation, ultimately affecting the mechanical properties of the cured product. Summary of the Invention

[0007] To address the problem of unreasonable processing time in existing epoxy resin compositions for preparing prepregs, this invention proposes an epoxy resin composition, its preparation method, and its application.

[0008] The epoxy resin composition of the present invention consists of component A and component B; the mass ratio of component A to component B is 100:(20-40);

[0009] Component A consists of liquid epoxy resin I and solid epoxy resin; the liquid epoxy resin I in component A is 20-50 parts and the solid epoxy resin is 40-80 parts.

[0010] Component B consists of liquid epoxy resin II, curing agent and accelerator; in component B, liquid epoxy resin II is 60-90 parts, curing agent is 2-10 parts and accelerator is 1-5 parts.

[0011] The softening point of the solid epoxy resin is 55-95℃; the softening points of liquid epoxy resin I and liquid epoxy resin II are below 25℃.

[0012] The preparation method of the above epoxy resin composition is carried out according to the following steps:

[0013] I. Preparation of Component A: The solid epoxy resin is melted by heating, and then liquid epoxy resin I is added. After stirring and mixing evenly, component A is obtained.

[0014] II. Preparation of Component B: Liquid epoxy resin II, curing agent and accelerator are mixed and ground, heated to 55-85℃, and stirred until uniform to obtain component B;

[0015] III. Preparation of epoxy resin composition: The A component obtained in step one and the B component obtained in step two are stirred and mixed evenly at 55-85℃, and the epoxy resin composition is obtained after cooling.

[0016] The method for preparing epoxy resin prepreg using the above epoxy resin composition is carried out according to the following steps:

[0017] 1. Weigh out the epoxy resin composition and carbon fiber;

[0018] 2. The epoxy resin composition is coated using a film coating machine to obtain an epoxy resin film; the coating temperature of the film coating machine is 70-90℃, and the coating speed is 4-12m / min.

[0019] 3. The carbon fiber is laid between two layers of epoxy resin film and then hot-pressed to obtain carbon fiber prepreg.

[0020] The principle and beneficial effects of this invention are as follows:

[0021] The epoxy resin composition of this invention comprises component A and component B. Component A consists of liquid epoxy resin I and solid epoxy resin, while component B consists of epoxy resin II, a curing agent, and an accelerator. Component A is prepared through a melt-mixing process of high-softening-point solid epoxy resin, while component B is prepared through a grinding process of the additives. This two-component design separates the preparation processes, avoiding the problems of high viscosity and uneven composition caused by the simultaneous addition of solid epoxy resin and additives. By selecting the type of resin, adjusting the resin ratio, and regulating the amount of additives, the curing speed of the resin composition is adjusted, resulting in a longer processing time during the coating process and producing a uniform film quality, suitable for mass production of prepregs.

[0022] In this invention, the addition of a high softening point solid epoxy resin results in a high viscosity of the resin composition at room temperature. The prepreg prepared does not flow during storage or transportation at room temperature, and its size and shape do not change significantly after the release paper is peeled off. This is beneficial for subsequent lamination and curing, and effectively improves the stability of prepreg storage and transportation as well as the quality of the final cured product.

[0023] This invention selects solid epoxy resin with high thermal stability and multifunctional liquid epoxy resin as raw materials. The solid epoxy resin used has excellent heat resistance and can maintain a stable chemical structure and physical properties at high temperatures with minimal loss of mechanical properties. The multifunctional liquid epoxy resin forms a high-density cross-linked network through intermolecular cross-linking reactions. The selected curing agent and accelerator promote the intermolecular cross-linking reactions, forming a more compact and stable chemical structure, thereby improving the heat resistance of the cured resin composition.

[0024] When the resin composition film of the present invention is laminated with fibers, the viscosity of the resin solution is low at the selected lamination temperature, which can completely wet the fibers and avoid problems such as pitting and dry yarn in the prepreg. The resin and fiber have good wettability and high interfacial bonding strength, resulting in excellent mechanical strength and heat resistance of the final cured product.

[0025] The epoxy resin composition of this invention has good processability and lay-up properties. The cured product of the epoxy resin composition has excellent heat resistance and mechanical strength properties, which can meet the requirements of composite materials used in the automotive and other fields for mechanical properties, heat resistance, lightweight and high strength. Furthermore, the prepreg and composite material raw materials provided by this invention are simple and readily available, low in cost, and suitable for rapid large-scale production. Detailed Implementation

[0026] The technical solution of the present invention is not limited to the specific embodiments listed below, but also includes any reasonable combination of the specific embodiments.

[0027] Specific Implementation Method 1: The epoxy resin composition of this embodiment consists of component A and component B; the mass ratio of component A to component B is 100:(20-40);

[0028] Component A consists of liquid epoxy resin I and solid epoxy resin; the liquid epoxy resin I in component A is 20-50 parts and the solid epoxy resin is 40-80 parts.

[0029] Component B consists of liquid epoxy resin II, curing agent and accelerator; in component B, liquid epoxy resin II is 60-90 parts, curing agent is 2-10 parts and accelerator is 1-5 parts.

[0030] The softening point of the solid epoxy resin is 55-95℃; the softening points of liquid epoxy resin I and liquid epoxy resin II are below 25℃.

[0031] The epoxy resin composition of this embodiment consists of component A and component B. Component A comprises liquid epoxy resin I and solid epoxy resin, while component B comprises epoxy resin II, a curing agent, and an accelerator. Component A is prepared through a melt-mixing process of high-softening-point solid epoxy resin, while component B is prepared through a grinding process of the additives. This two-component design separates the preparation processes, avoiding the problems of high viscosity and uneven composition of the adhesive caused by the simultaneous addition of solid epoxy resin and additives. By selecting the type of resin, adjusting the resin ratio, and regulating the amount of additives, the curing speed of the resin composition is adjusted, resulting in a longer processing time during the coating process and producing a uniform film quality, suitable for mass production of prepregs.

[0032] In this embodiment, the addition of high softening point solid epoxy resin results in a high viscosity of the resin composition at room temperature. The prepreg prepared does not flow during storage or transportation at room temperature, and its size and shape do not change significantly after the release paper is peeled off. This is beneficial for subsequent lamination and curing, and effectively improves the stability of prepreg storage and transportation as well as the quality of the final cured product.

[0033] This embodiment uses solid epoxy resin with high thermal stability and multifunctional liquid epoxy resin as raw materials. The solid epoxy resin has excellent heat resistance and can maintain a stable chemical structure and physical properties at high temperatures with minimal loss of mechanical properties. The multifunctional liquid epoxy resin forms a high-density cross-linked network through intermolecular cross-linking reactions. The selected curing agent and accelerator promote the intermolecular cross-linking reactions, forming a more compact and stable chemical structure, thereby improving the heat resistance of the cured resin composition.

[0034] When the resin composition film of this embodiment is laminated with the fiber, the viscosity of the resin solution is low at the selected lamination temperature, which can completely wet the fiber and avoid problems such as pitting and dry yarn in the prepreg. The resin and fiber have good wettability and high interfacial bonding strength, resulting in excellent mechanical strength and heat resistance of the final cured product.

[0035] The epoxy resin composition of this embodiment has good processability and lay-up properties. The cured product of the epoxy resin composition has excellent heat resistance and mechanical strength properties, which can meet the requirements of composite materials used in the automotive and other fields for mechanical properties, heat resistance, lightweight and high strength. Furthermore, the prepreg and composite material raw materials provided in this embodiment are simple and readily available, low in cost, and suitable for rapid large-scale production.

[0036] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the curing agent is a dicyandiamide-based curing agent.

[0037] Specific Implementation Method 3: This implementation method differs from Specific Implementation Method 1 or 2 in that the liquid epoxy resin I is a liquid bisphenol A type epoxy resin, a liquid alicyclic epoxy resin, a liquid aliphatic epoxy resin, a liquid bisphenol F type epoxy resin, a liquid phenolic type epoxy resin, or a liquid glycidylamine type epoxy resin.

[0038] Specific Implementation Method Four: This implementation method differs from one of Specific Implementation Methods One to Three in that the liquid epoxy resin II is a liquid bisphenol A type epoxy resin, a liquid alicyclic epoxy resin, a liquid aliphatic epoxy resin, a liquid bisphenol F type epoxy resin, a liquid phenolic type epoxy resin, or a liquid glycidylamine type epoxy resin.

[0039] Specific Implementation Method Five: This implementation method differs from one of the specific implementation methods one to four in that the accelerator is an organic urea.

[0040] Specific Implementation Method Six: The preparation method of the epoxy resin composition in this implementation method is carried out according to the following steps:

[0041] I. Preparation of Component A: The solid epoxy resin is melted by heating, and then liquid epoxy resin I is added. After stirring and mixing evenly, component A is obtained.

[0042] II. Preparation of Component B: Liquid epoxy resin II, curing agent and accelerator are mixed and ground, heated to 55-85℃, and stirred until uniform to obtain component B;

[0043] III. Preparation of epoxy resin composition: The A component obtained in step one and the B component obtained in step two are stirred and mixed evenly at 55-85℃, and the epoxy resin composition is obtained after cooling.

[0044] The epoxy resin composition of this embodiment consists of component A and component B. Component A comprises liquid epoxy resin I and solid epoxy resin, while component B comprises epoxy resin II, a curing agent, and an accelerator. Component A is prepared through a melt-mixing process of high-softening-point solid epoxy resin, while component B is prepared through a grinding process of the additives. This two-component design separates the preparation processes, avoiding the problems of high viscosity and uneven composition of the adhesive caused by the simultaneous addition of solid epoxy resin and additives. By selecting the type of resin, adjusting the resin ratio, and regulating the amount of additives, the curing speed of the resin composition is adjusted, resulting in a longer processing time during the coating process and producing a uniform film quality, suitable for mass production of prepregs.

[0045] In this embodiment, the addition of high softening point solid epoxy resin results in a high viscosity of the resin composition at room temperature. The prepreg prepared does not flow during storage or transportation at room temperature, and its size and shape do not change significantly after the release paper is peeled off. This is beneficial for subsequent lamination and curing, and effectively improves the stability of prepreg storage and transportation as well as the quality of the final cured product.

[0046] This embodiment uses solid epoxy resin with high thermal stability and multifunctional liquid epoxy resin as raw materials. The solid epoxy resin has excellent heat resistance and can maintain a stable chemical structure and physical properties at high temperatures with minimal loss of mechanical properties. The multifunctional liquid epoxy resin forms a high-density cross-linked network through intermolecular cross-linking reactions. The selected curing agent and accelerator promote the intermolecular cross-linking reactions, forming a more compact and stable chemical structure, thereby improving the heat resistance of the cured resin composition.

[0047] When the resin composition film of this embodiment is laminated with the fiber, the viscosity of the resin solution is low at the selected lamination temperature, which can completely wet the fiber and avoid problems such as pitting and dry yarn in the prepreg. The resin and fiber have good wettability and high interfacial bonding strength, resulting in excellent mechanical strength and heat resistance of the final cured product.

[0048] The epoxy resin composition of this embodiment has good processability and lay-up properties. The cured product of the epoxy resin composition has excellent heat resistance and mechanical strength properties, which can meet the requirements of composite materials used in the automotive and other fields for mechanical properties, heat resistance, lightweight and high strength. Furthermore, the prepreg and composite material raw materials provided in this embodiment are simple and readily available, low in cost, and suitable for rapid large-scale production.

[0049] Specific Implementation Method Seven: This implementation method for preparing epoxy resin prepreg using an epoxy resin composition is carried out according to the following steps:

[0050] 1. Weigh out the epoxy resin composition and carbon fiber;

[0051] 2. The epoxy resin composition is coated using a film coating machine to obtain an epoxy resin film; the coating temperature of the film coating machine is 70-90℃, and the coating speed is 4-12m / min.

[0052] 3. The carbon fiber is laid between two layers of epoxy resin film and then hot-pressed to obtain carbon fiber prepreg.

[0053] The epoxy resin composition of this embodiment consists of component A and component B. Component A comprises liquid epoxy resin I and solid epoxy resin, while component B comprises epoxy resin II, a curing agent, and an accelerator. Component A is prepared through a melt-mixing process of high-softening-point solid epoxy resin, while component B is prepared through a grinding process of the additives. This two-component design separates the preparation processes, avoiding the problems of high viscosity and uneven composition of the adhesive caused by the simultaneous addition of solid epoxy resin and additives. By selecting the type of resin, adjusting the resin ratio, and regulating the amount of additives, the curing speed of the resin composition is adjusted, resulting in a longer processing time during the coating process and producing a uniform film quality, suitable for mass production of prepregs.

[0054] In this embodiment, the addition of high softening point solid epoxy resin results in a high viscosity of the resin composition at room temperature. The prepreg prepared does not flow during storage or transportation at room temperature, and its size and shape do not change significantly after the release paper is peeled off. This is beneficial for subsequent lamination and curing, and effectively improves the stability of prepreg storage and transportation as well as the quality of the final cured product.

[0055] This embodiment uses solid epoxy resin with high thermal stability and multifunctional liquid epoxy resin as raw materials. The solid epoxy resin has excellent heat resistance and can maintain a stable chemical structure and physical properties at high temperatures with minimal loss of mechanical properties. The multifunctional liquid epoxy resin forms a high-density cross-linked network through intermolecular cross-linking reactions. The selected curing agent and accelerator promote the intermolecular cross-linking reactions, forming a more compact and stable chemical structure, thereby improving the heat resistance of the cured resin composition.

[0056] When the resin composition film of this embodiment is laminated with the fiber, the viscosity of the resin solution is low at the selected lamination temperature, which can completely wet the fiber and avoid problems such as pitting and dry yarn in the prepreg. The resin and fiber have good wettability and high interfacial bonding strength, resulting in excellent mechanical strength and heat resistance of the final cured product.

[0057] The epoxy resin composition of this embodiment has good processability and lay-up properties. The cured product of the epoxy resin composition has excellent heat resistance and mechanical strength properties, which can meet the requirements of composite materials used in the automotive and other fields for mechanical properties, heat resistance, lightweight and high strength. Furthermore, the prepreg and composite material raw materials provided in this embodiment are simple and readily available, low in cost, and suitable for rapid large-scale production.

[0058] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Method Seven in that the mass ratio of epoxy resin and carbon fiber in step one is 30-45:55-70.

[0059] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Method Seven in that the areal density of the epoxy resin film described in step two is 20-200 g / m³. 2 .

[0060] Specific Implementation Method 10: This implementation method differs from Specific Implementation Method 7 in that the temperature of the pressure roller during hot pressing and lamination in step 3 is 90-120℃, and the lamination speed is 4-12m / min.

[0061] Example 1

[0062] The preparation method of the epoxy resin composition in this embodiment is carried out according to the following steps:

[0063] I. Preparation of Component A: Weigh 30 parts of glycidylamine type liquid epoxy resin and 70 parts of solid phenolic epoxy resin, heat to melt the solid phenolic epoxy resin, then add glycidylamine type liquid epoxy resin, stir and mix evenly to obtain component A.

[0064] The softening point of the glycidylamine type liquid epoxy resin is 16℃.

[0065] The softening point of the solid phenolic epoxy resin is 85°C.

[0066] II. Preparation of Component B: Mix 70 parts of glycidylamine type liquid epoxy resin, 5 parts of dicyandiamide curing agent and 3 parts of organic urea and grind them. Heat to 70°C and stir until uniformly mixed to obtain Component B.

[0067] The softening point of the glycidylamine type liquid epoxy resin is 16℃.

[0068] III. Preparation of epoxy resin composition: The A component obtained in step one and the B component obtained in step two are stirred and mixed evenly at 80°C, and the mixture is cooled to obtain the epoxy resin composition.

[0069] The mass ratio of component A to component B is 100:30;

[0070] The method for preparing epoxy resin prepreg using the above epoxy resin composition is carried out according to the following steps:

[0071] 1. Weigh the epoxy resin composition and carbon fiber; the mass ratio of the epoxy resin to the carbon fiber is 40:60; the carbon fiber is T700 grade carbon fiber;

[0072] 2. The epoxy resin composition is coated using a film-coating machine to obtain an epoxy resin film; the coating temperature of the film-coating machine is 75℃, and the coating speed is 8m / min; the areal density of the epoxy resin film is 150g / m³. 2 ;

[0073] 3. The carbon fiber is laid between two layers of epoxy resin film and hot-pressed to obtain carbon fiber prepreg; the temperature of the pressure roller during hot-pressing is 115℃ and the bonding speed is 4m / min.

[0074] The prepreg prepared in Example 1 had a basis weight of 357-364 g / m³. 2 The resin content was approximately 33.5%, and the thickness was 0.22-0.24 mm. The mechanical properties of the composite material prepared from the prepreg were tested. The tensile strength in the 0° direction of the composite material reached 1805.41 MPa, and the unidirectional flexural modulus in the 0° direction was 109.52 GPa, showing good mechanical properties.

[0075] Example 2

[0076] The preparation method of the epoxy resin composition in this embodiment is carried out according to the following steps:

[0077] I. Preparation of Component A: Weigh 30 parts of glycidylamine type liquid epoxy resin and 70 parts of solid phenolic epoxy resin, heat to melt the solid phenolic epoxy resin, then add glycidylamine type liquid epoxy resin, stir and mix evenly to obtain component A.

[0078] The softening point of the glycidylamine type liquid epoxy resin is 12℃.

[0079] The softening point of the solid phenolic epoxy resin is 83°C.

[0080] II. Preparation of Component B: Mix 80 parts of glycidylamine type liquid epoxy resin, 8 parts of dicyandiamide curing agent and 4 parts of organic urea and grind them. Heat to 75°C and stir until uniformly mixed to obtain Component B.

[0081] The softening point of the glycidylamine type liquid epoxy resin is 12℃.

[0082] III. Preparation of epoxy resin composition: The A component obtained in step one and the B component obtained in step two are stirred and mixed evenly at 80°C, and the mixture is cooled to obtain the epoxy resin composition.

[0083] The mass ratio of component A to component B is 100:25;

[0084] The method for preparing epoxy resin prepreg using the above epoxy resin composition is carried out according to the following steps:

[0085] 1. Weigh the epoxy resin composition and carbon fiber; the mass ratio of the epoxy resin to the carbon fiber is 40:60; the carbon fiber is T700 grade carbon fiber;

[0086] 2. The epoxy resin composition is coated using a film-coating machine to obtain an epoxy resin film; the coating temperature of the film-coating machine is 75℃, and the coating speed is 8m / min; the areal density of the epoxy resin film is 158g / m³. 2 ;

[0087] 3. The carbon fiber is laid between two layers of epoxy resin film and hot-pressed to obtain carbon fiber prepreg; the temperature of the pressure roller during hot-pressing is 120℃ and the bonding speed is 4m / min.

[0088] The prepreg prepared in Example 2 had a basis weight of 358-362 g / m³. 2 The resin content was approximately 32.2%, and the thickness was 0.22-0.24 mm. The mechanical properties of the composite material prepared from the prepreg were tested. The tensile strength in the 0° direction of the composite material reached 1780 MPa, and the unidirectional flexural modulus in the 0° direction was 108 GPa, showing good mechanical properties.

[0089] Example 3

[0090] The preparation method of the epoxy resin composition in this embodiment is carried out according to the following steps:

[0091] I. Preparation of Component A: Take 40 parts of glycidylamine type liquid epoxy resin and 60 parts of solid o-cresol formaldehyde epoxy resin, heat to melt the solid o-cresol formaldehyde epoxy resin, then add glycidylamine type liquid epoxy resin, stir and mix evenly to obtain component A.

[0092] The softening point of the glycidylamine type liquid epoxy resin is 18°C.

[0093] The softening point of the solid o-cresol epoxy resin is 89°C.

[0094] II. Preparation of Component B: Mix 65 parts of bisphenol A type liquid epoxy resin, 5 parts of dicyandiamide curing agent and 2 parts of organic urea and grind them. Heat to 75°C and stir until uniformly mixed to obtain Component B.

[0095] The softening point of the bisphenol A type liquid epoxy resin is 17°C.

[0096] III. Preparation of epoxy resin composition: The A component prepared in step one and the B component prepared in step two are stirred and mixed evenly at 80°C, and the epoxy resin composition is obtained after cooling.

[0097] The mass ratio of component A to component B is 100:35;

[0098] The method for preparing epoxy resin prepreg using the above epoxy resin composition is carried out according to the following steps:

[0099] 1. Weigh the epoxy resin composition and carbon fiber; the mass ratio of the epoxy resin to the carbon fiber is 40:60; the carbon fiber is T700 grade carbon fiber;

[0100] 2. The epoxy resin composition is coated using a film-coating machine to obtain an epoxy resin film; the coating temperature of the film-coating machine is 75℃, and the coating speed is 8m / min; the areal density of the epoxy resin film is 155g / m³. 2 ;

[0101] 3. The carbon fiber is laid between two layers of epoxy resin film and hot-pressed to obtain carbon fiber prepreg; the temperature of the pressure roller during hot-pressing is 115℃ and the bonding speed is 5m / min.

[0102] The prepreg prepared in Example 3 had a basis weight of 359-363 g / m³. 2 The resin content was approximately 33.5%, and the thickness was 0.22-0.24 mm. The mechanical properties of the composite material prepared from the prepreg were tested. The tensile strength in the 0° direction of the composite material reached 1790 MPa, and the unidirectional flexural modulus in the 0° direction was 107 GPa, showing good mechanical properties.

Claims

1. A process for the preparation of an epoxy resin prepreg, characterised in that: The preparation method of the epoxy resin prepreg is carried out according to the following steps: I. The epoxy resin composition and carbon fibers are weighed; the mass ratio of the epoxy resin and the carbon fibers is 40:60; the carbon fibers are T700-grade carbon fibers; II. The epoxy resin composition is coated by a film coater to obtain an epoxy resin film; the temperature of the film coater is 75°C, and the coating speed is 8 m / min; the areal density of the epoxy resin film is 150 g / m 2 ; III. The carbon fibers are laid between the two layers of epoxy resin films and hot-pressed to be compounded to obtain carbon fiber prepreg; the temperature of the press roller is 115 DEG C during the hot pressing and the compounding speed is 4 m / min; The prepared prepreg has a grammage of 357-364 g / m 2 between 357-364 g / m, a resin content of 33.5%, a thickness of 0.22-0.24 mm; a 0° unidirectional tensile strength of 1805.41 MPa, and a 0° unidirectional bending modulus of 109.52 GPa; The preparation method of the epoxy resin composition is carried out according to the following steps: I. Preparation of A component: 30 parts of glycidyl amine type liquid epoxy resin and 70 parts of solid phenolic epoxy resin are weighed, the solid phenolic epoxy resin is melted by heating, then the glycidyl amine type liquid epoxy resin is added, and after stirring and mixing uniformly, A component is obtained; The softening point of the solid phenolic epoxy resin is 85 DEG C; II. Preparation of B component: 70 parts of glycidyl amine type liquid epoxy resin, 5 parts of dicyandiamide curing agent and 3 parts of organic urea are mixed and ground, heated to 70 DEG C, and stirred and mixed uniformly to obtain B component; III. Preparation of the epoxy resin composition: A component prepared in step I and B component prepared in step II are stirred and mixed uniformly at 80 DEG C, and after cooling, the epoxy resin composition is obtained; The mass ratio of the A component and the B component is 100:30; The softening point of the glycidyl amine type liquid epoxy resin is 16 DEG C.