Epoxy resin vacuum infusion system and preparation method and application thereof

Abstract

The invention relates to the technical field of composite material preparation, and discloses a vacuum infusion epoxy resin system which comprises the following components in parts by weight: 50-80 parts of epoxy resin, 10-30 parts of a curing agent, 1-5 parts of an accelerant, 5-15 parts of a flexibilizer, 10-20 parts of filler, 1-3 parts of a coupling agent, 5-10 parts of a diluent, 0.1-1 part of a defoaming agent, 0.5-2 parts of an antioxidant and 0.5-2 parts of a light stabilizer. Low-temperature rapid curing is achieved through the synergistic effect of the modified aromatic amine curing agent and the accelerant, the carboxyl-terminated nitrile rubber toughening agent and the filler form a synergistic toughening system to improve the mechanical property, and the hydrogenated bisphenol A epoxy resin is matched with the light stabilizer and the antioxidant to enhance the weather resistance and the high temperature resistance. The system can be used for preparing composite materials in the fields of wind power generation blades, ships, aerospace and the like, fiber reinforced materials are infiltrated by adopting a vacuum infusion forming process and then are cured and formed, and the problems that an existing resin system is long in curing time and insufficient in mechanical property and weather resistance are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of composite material preparation, in particular to a vacuum infusion epoxy resin system and a preparation method and application thereof. Background Art

[0002] The vacuum infusion molding process is an efficient composite material molding method that is widely used in wind turbine blades, ships, aerospace and other fields. This process uses a vacuum environment to absorb the resin system into a mold lined with fiber-reinforced materials to achieve resin infiltration and curing of the fibers, thereby forming a high-performance composite material. Epoxy resin has become a commonly used resin matrix in vacuum infusion molding due to its excellent mechanical properties, chemical corrosion resistance and good processability.

[0003] However, existing vacuum infusion epoxy resin systems still have some shortcomings. For example, some resin systems have long curing times, resulting in low production efficiency; the toughness and fatigue resistance of some resins need to be improved, which affects the service life of the composite materials; and in terms of high temperature resistance and weather resistance, existing resin systems also lack the ability to meet the requirements of some special environments. Therefore, the development of a vacuum infusion epoxy resin system with faster curing speed, superior mechanical properties, and weather resistance is of great practical significance. Summary of the Invention

[0004] In response to the deficiencies of the prior art, the present invention provides a vacuum infusion epoxy resin system and a preparation method and application thereof, which solve the problems of the existing resin system such as long curing time, insufficient mechanical properties and weather resistance.

[0005] To achieve the above objectives, the present invention is implemented through the following technical scheme: a vacuum infusion epoxy resin system and its preparation method and application, comprising the following components in parts by weight: 50 to 80 parts of epoxy resin, 10 to 30 parts of curing agent, 1 to 5 parts of accelerator, 5 to 15 parts of toughening agent, 10 to 20 parts of filler, 1 to 3 parts of coupling agent, 5 to 10 parts of diluent, 0.1 to 1 part of defoaming agent, 0.5 to 2 parts of antioxidant, and 0.5 to 2 parts of light stabilizer.

[0006] Preferably, the epoxy resin is one or more combinations of bisphenol A epoxy resin, bisphenol F epoxy resin, and hydrogenated bisphenol A epoxy resin, preferably a mixture of bisphenol A epoxy resin and hydrogenated bisphenol A epoxy resin, with a weight ratio of (1-3):1.

[0007] Preferably, the curing agent is a modified aromatic amine curing agent obtained by modifying 4,4'-diaminodiphenylmethane with maleic anhydride, wherein the modification process is as follows: reacting 4,4'-diaminodiphenylmethane with maleic anhydride in a molar ratio of 1:(1.1-1.3) at 110-130°C for 3-5 hours.

[0008] Preferably, the accelerator is 2-methylimidazole, and the toughening agent is carboxyl-terminated nitrile rubber with a molecular weight of 3000-5000.

[0009] Preferably, the filler is a mixture of nano-silica and hollow glass microspheres, with a weight ratio of (0.5-1.5):1, the nano-silica particle size is 50-100 nm, and the hollow glass microsphere particle size is 50-200 μm.

[0010] Preferably, the coupling agent is γ-glycidyloxypropyltrimethoxysilane, the diluent is benzyl alcohol, the defoaming agent is a polyether-modified silicon defoaming agent, the antioxidant is 2,6-di-tert-butyl-p-cresol, and the light stabilizer is bis(1,2,2,6,6-pentamethylpiperidinyl)sebacate.

[0011] Preferably, the weight ratio of the bisphenol A epoxy resin to the hydrogenated bisphenol A epoxy resin is 2:1.

[0012] Preferably, the molar ratio of 4,4'-diaminodiphenylmethane to maleic anhydride is 1:1.2, the reaction temperature is 120°C, and the reaction time is 4 hours.

[0013] Preferably, the preparation method of the vacuum infusion epoxy resin system comprises the following steps: S1. The epoxy resin, diluent and toughening agent are stirred at 50-70 ° C to obtain a mixture A; S2. Add a curing agent, an accelerator, a coupling agent, an antioxidant and a light stabilizer to the mixture A and stir for 10 to 20 minutes to obtain a mixture B; S3. Add the filler and defoamer to the mixture B, and disperse them with high-speed stirring for 30 to 60 minutes to obtain the epoxy resin system.

[0014] Preferably, the vacuum infusion epoxy resin system is used to prepare composite materials for wind turbine blades, ships or aerospace fields, and the fiber-reinforced material is infiltrated and then cured to form the composite materials using a vacuum infusion molding process.

[0015] The present invention provides a vacuum infusion epoxy resin system and its preparation method and application. It has the following beneficial effects: 1. The present invention significantly reduces the activation energy of the curing reaction through the synergistic effect of the modified aromatic amine curing agent and the 2-methylimidazole accelerator, achieves low-temperature rapid curing, greatly shortens the curing time compared with the existing technology, improves production efficiency, and solves the problem of low production efficiency caused by the long curing time of the existing resin system.

[0016] 2. The present invention forms a synergistic toughening system by forming a carboxyl-terminated nitrile rubber toughening agent with nano-silica and hollow glass microsphere filler, constructing an elastic phase-rigid particle composite structure in the resin matrix, effectively improving the tensile strength, impact toughness and fatigue resistance of the composite material, and improving the defect of insufficient toughness of existing resins.

[0017] 3. The present invention combines hydrogenated bisphenol A epoxy resin with a hindered amine light stabilizer and an antioxidant. The alicyclic structure shields ultraviolet rays and the antioxidant group captures free radicals, significantly enhancing the resin's weather resistance and high temperature resistance. This makes the composite material less prone to aging when used outdoors for a long time in a high temperature environment of 120°C, solving the problem of insufficient weather resistance and heat resistance of the existing system. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a flow chart of the method of Example 1 of the present invention; Figure 2 This is a flow chart of the method of embodiment 2 of the present invention; Figure 3 This is a process optimization flow chart of Example 3 of the present invention. DETAILED DESCRIPTION

[0019] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0020] Example 1: Please see the attached Figure 1 The embodiment of the present invention provides a vacuum infusion epoxy resin system for a highly weather-resistant wind turbine blade, comprising the following components in parts by weight: Epoxy resin: 40 parts of bisphenol A epoxy resin, 20 parts of hydrogenated bisphenol A epoxy resin; Curing agent: 20 parts of modified aromatic amine curing agent, prepared by reacting 4,4'-diaminodiphenylmethane and maleic anhydride in a molar ratio of 1:1.2 at 120°C for 4 hours; Accelerator: 3 parts of 2-methylimidazole; Toughening agent: 10 parts of carboxyl-terminated nitrile rubber, molecular weight 4000; Filler: 10 parts of nano-silica, particle size 80nm, 10 parts of hollow glass microspheres, particle size 100μm; Coupling agent: 2 parts of γ-glycidyloxypropyltrimethoxysilane; Diluent: 8 parts of benzyl alcohol; Defoaming agent: 0.5 parts of polyether modified silicone defoaming agent; Antioxidant: 1 part of 2,6-di-tert-butyl-p-cresol; Light stabilizer: 1 part of bis(1,2,2,6,6-pentamethylpiperidinyl) sebacate.

[0021] The alicyclic structure of hydrogenated bisphenol A epoxy resin absorbs 75% of ultraviolet light at 290-400nm. Combined with the hindered amine light stabilizer, it captures free radicals and effectively inhibits resin aging. The modified aromatic amine curing agent and 2-methylimidazole synergistically reduce the curing activation energy, making low-temperature rapid curing possible. Nano-silica and hollow glass microspheres work synergistically to improve mechanical properties while achieving lightweight composite materials.

[0022] A method for preparing a vacuum infusion epoxy resin system for a highly weather-resistant wind turbine blade comprises the following steps: S1. Compatibilization and toughening treatment: Bisphenol A epoxy resin, hydrogenated bisphenol A epoxy resin, and benzyl alcohol were added to a reactor and stirred at 2000 rpm at 60°C for 15 minutes until homogeneous. Carboxyl-terminated nitrile rubber was added, and the temperature was raised to 65°C and stirred for 30 minutes to obtain a mixture A. A pre-esterification reaction of the carboxyl end groups with the epoxy groups formed a 50-100 nm elastomer dispersion in the resin matrix, providing stress buffer nodes for subsequent curing. S2. Construction of curing catalyst system: Add modified aromatic amine curing agent and 2-methylimidazole, stir at 1500rpm for 15 minutes, and use the polar imide group introduced by maleic anhydride modification to form hydrogen bond coordination with the imidazole ring to construct a high-efficiency catalytic system; then add coupling agent, antioxidant, and light stabilizer, stir for 10 minutes to obtain mixture B. The coupling agent condenses with the hydroxyl group on the surface of nano-silica through silaneoxy, and the epoxy group is pre-crosslinked with the epoxy resin to strengthen the filler-resin interface bonding.

[0023] S3. Filler dispersion and homogenization: Add nano-silica, hollow glass microspheres, and defoaming agent, and disperse at a high speed of 5000 rpm for 45 minutes. The bridging effect of the coupling agent achieves uniform dispersion of the filler. The nano-silica hinders crack propagation through the "pinning effect", and the hollow glass microspheres reduce the system density and improve fluidity.

[0024] The above system was used to prepare the web of a 1.5MW wind turbine blade: 8 layers of glass fiber fabric were laid in the mold, and a vacuum infusion process was adopted. The cured material was cured at 80°C for 2 hours. The tensile strength of the resulting composite material reached 88MPa, which was 28% higher than that of the traditional system. After 500 hours of ultraviolet irradiation, the strength retention rate was 92%, significantly better than the 75% of commercially available products.

[0025] Example 2: An embodiment of the present invention provides a low-viscosity vacuum infusion epoxy resin system for a ship sandwich structure, comprising the following components in parts by weight: Epoxy resin: 30 parts of bisphenol F epoxy resin, 30 parts of hydrogenated bisphenol A epoxy resin; Curing agent: 25 parts of modified aromatic amine curing agent, prepared by reacting 4,4'-diaminodiphenylmethane and maleic anhydride in a molar ratio of 1:1.1 at 110°C for 5 hours; Accelerator: 4 parts of 2-methylimidazole; Toughening agent: 12 parts of carboxyl-terminated nitrile rubber, molecular weight 3000; Filler: 8 parts of nano-silica, particle size 50nm, 12 parts of hollow glass microspheres, particle size 150μm; Coupling agent: 2.5 parts of γ-glycidyloxypropyltrimethoxysilane; Diluent: 9 parts of benzyl alcohol; Other additives: the same as in Example 1.

[0026] The flexible molecular structure of bisphenol F epoxy resin and the benzyl alcohol diluent synergistically reduce the system viscosity and improve fiber impregnation. The carboxyl-terminated nitrile rubber and nano-silica form a dual toughening structure of "flexible phase-rigid particles". Under impact loads, the elastomer dispersed phase undergoes plastic deformation to absorb energy, and the nano-silica hinders crack propagation through interfacial friction. The low density of the hollow glass microspheres reduces the system density to 1.22g / cm³, meeting the demand for lightweight ships.

[0027] A method for preparing a low-viscosity vacuum infusion epoxy resin system for a ship sandwich structure comprises the following steps: S1. Pre-dispersion and viscosity control: Bisphenol F epoxy resin, hydrogenated bisphenol A epoxy resin, and benzyl alcohol were added to a reactor and stirred at 50°C for 10 minutes. After adding carboxyl-terminated nitrile rubber, the mixture was dispersed using a 20kHz ultrasonic wave at 300W for 15 minutes. The ortho-methyl structure of the bisphenol F resin reduces intermolecular forces, lowering the viscosity of the system to 600 mPa·s at 25°C. This also achieved nanoscale uniform dispersion of the toughening agent. S2 and S3. Curing and filler mixing: Add curing agent, accelerator, coupling agent, antioxidant, and light stabilizer in sequence and stir for 15 minutes; add filler and defoamer and disperse at high speed for 30 minutes. The spherical structure of hollow glass microspheres is used to further optimize the resin fluidity and increase the permeability to 6.5 mm / s.

[0028] The above system was used to prepare the sandwich layer of the fiberglass yacht hull: carbon fiber fabric was laid on the surface of the PVC foam core material, and a vacuum infusion process was adopted. After curing at room temperature for 24 hours, the mold was removed. The impact toughness of the composite material reached 25kJ / m², which is 67% higher than that of the traditional system, and there is no fiber dry spot defect.

[0029] Example 3: An embodiment of the present invention provides a high-temperature resistant vacuum infusion epoxy resin system for aerospace, comprising the following components in parts by weight: Epoxy resin: 50 parts of bisphenol A epoxy resin, 30 parts of hydrogenated bisphenol A epoxy resin; Curing agent: 18 parts of modified aromatic amine curing agent, prepared by reacting 4,4'-diaminodiphenylmethane and maleic anhydride in a molar ratio of 1:1.3 at 130°C for 3 hours; Accelerator: 2 parts of 2-methylimidazole; Toughening agent: 8 parts of carboxyl-terminated nitrile rubber, molecular weight 5000; Filler: 15 parts of nano-silica, particle size 100nm, 5 parts of hollow glass microspheres, particle size 200μm; Coupling agent: 2 parts of γ-glycidyloxypropyltrimethoxysilane; Diluent: 8 parts of benzyl alcohol; Antioxidant: 2 parts of 2,6-di-tert-butyl-p-cresol; Other additives: the same as in Example 1.

[0030] The curing agent modified with excess maleic anhydride forms a rigid imide ring during the curing process, which cross-links with the epoxy resin to form a conjugated rigid network, thereby improving the thermal stability of the molecular chain; the high proportion of hydrogenated bisphenol A epoxy resin added increases the content of the alicyclic structure, inhibiting the movement of molecular chain segments at high temperatures; nano-silica reduces the freedom of the matrix molecular chain, and the antioxidant captures the free radicals generated by thermal oxidation. The three work together to delay the high-temperature aging process and increase the glass transition temperature of the system to 155°C.

[0031] Optimization of the curing process of a high-temperature resistant vacuum infusion epoxy resin system for aerospace applications: Step temperature curing process: After mixing the components according to the method of Example 1, pre-curing at 60°C for 1 hour to promote the initial cross-linking of low-reactive groups, main curing at 80°C for 2 hours to complete the main cross-linking reaction, and post-curing at 120°C for 2 hours to eliminate residual stress and increase the degree of cure to 98.7%; Heat-resistant interface strengthening: By increasing the amount of antioxidants and optimizing the filler dispersion process, a denser chemical bonding network is formed between nano-silica and the resin matrix, inhibiting interface debonding at high temperatures.

[0032] The above system is used to prepare UAV skins: the system is infused between carbon fiber prepreg layers, and after step-by-step temperature curing, the skin is placed in a high-temperature environment of 120°C for 1000 hours. The bending strength retention rate is 95%, which is significantly better than the 80% of the traditional system.

[0033] Comparative example: Commercially available ordinary vacuum infusion epoxy resin system The system composition, components by weight include: Epoxy resin: 70 parts of bisphenol A epoxy resin; Curing agent: 20 parts of unmodified 4,4'-diaminodiphenylmethane; Accelerator: 2 parts of benzyldimethylamine; Toughening agent: 8 parts of liquid nitrile rubber; Filler: 15 parts of micron silicon dioxide, particle size 5μm, without hollow glass microspheres; Diluent: 7 parts of acetone; No antioxidants or light stabilizers.

[0034] The preparation method is: stirring and mixing the components at room temperature without any special dispersion or catalytic treatment.

[0035] The curing performance, mechanical properties, weather resistance, high temperature resistance and density of the epoxy resin systems of Example 1, Example 2, Example 3 and the comparative example were tested. The test results are shown in the following table: A comparison of the system performance of Examples 1-3 and the comparative example shows that the vacuum infusion epoxy resin system of the present invention exhibits significant advantages in curing efficiency, mechanical properties, weather resistance, high temperature resistance, and process adaptability. The comparative example suffers from shortcomings such as slow curing, weak interfacial bonding, and poor weathering and heat resistance due to its lack of key modifying components, the use of traditional micron fillers, and simple processing. The present invention, through component design and process innovation, addresses the pain points of the prior art, offering significant technological advancement and industrial application value.

[0036] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. Vacuum infusion epoxy resin system, characterized in that, The invention comprises the following components in parts by weight: 50 to 80 parts of epoxy resin, 10 to 30 parts of curing agent, 1 to 5 parts of accelerator, 5 to 15 parts of toughening agent, 10 to 20 parts of filler, 1 to 3 parts of coupling agent, 5 to 10 parts of diluent, 0.1 to 1 part of defoaming agent, 0.5 to 2 parts of antioxidant and 0.5 to 2 parts of light stabilizer.

2. The vacuum infusion epoxy resin system according to claim 1, characterized in that: The epoxy resin is one or more combinations of bisphenol A epoxy resin, bisphenol F epoxy resin, and hydrogenated bisphenol A epoxy resin, preferably a mixture of bisphenol A epoxy resin and hydrogenated bisphenol A epoxy resin, with a weight ratio of (1-3):

1.

3. The vacuum infusion epoxy resin system according to claim 1, characterized in that: The curing agent is a modified aromatic amine curing agent obtained by modifying 4,4'-diaminodiphenylmethane with maleic anhydride. The modification process is: reacting 4,4'-diaminodiphenylmethane with maleic anhydride in a molar ratio of 1:(1.1-1.3) at 110-130°C for 3-5 hours to obtain the curing agent.

4. The vacuum infusion epoxy resin system according to claim 1, characterized in that: The accelerator is 2-methylimidazole, and the toughening agent is carboxyl-terminated nitrile rubber with a molecular weight of 3000-5000.

5. The vacuum infusion epoxy resin system according to claim 1, characterized in that: The filler is a mixture of nano-silicon dioxide and hollow glass microspheres, with a weight ratio of (0.5-1.5):

1. The particle size of the nano-silicon dioxide is 50-100 nm, and the particle size of the hollow glass microspheres is 50-200 μm.

6. The vacuum infusion epoxy resin system according to claim 1, characterized in that: The coupling agent is γ-glycidyloxypropyltrimethoxysilane, the diluent is benzyl alcohol, the defoaming agent is a polyether-modified silicon defoaming agent, the antioxidant is 2,6-di-tert-butyl-p-cresol, and the light stabilizer is bis(1,2,2,6,6-pentamethylpiperidinyl) sebacate.

7. The vacuum infusion epoxy resin system according to claim 2, characterized in that: The weight ratio of the bisphenol A epoxy resin to the hydrogenated bisphenol A epoxy resin is 2:

1.

8. The vacuum infusion epoxy resin system according to claim 3, characterized in that: The molar ratio of 4,4'-diaminodiphenylmethane to maleic anhydride is 1:1.2, the reaction temperature is 120°C, and the reaction time is 4 hours.

9. A method for preparing a vacuum infusion epoxy resin system according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1. The epoxy resin, diluent and toughening agent are stirred at 50-70 ° C to obtain a mixture A; S2. Add a curing agent, an accelerator, a coupling agent, an antioxidant and a light stabilizer to the mixture A and stir for 10 to 20 minutes to obtain a mixture B; S3. Add the filler and defoamer to the mixture B, and disperse them with high-speed stirring for 30 to 60 minutes to obtain the epoxy resin system.

10. Use of the vacuum infusion epoxy resin system according to any one of claims 1 to 8, characterized in that: The epoxy resin system is used for preparing composite materials for wind power generation blades, ships or aerospace fields, and is formed by infiltrating fiber-reinforced materials through a vacuum infusion molding process and then curing.

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