Recyclable epoxy resin matrix and preparation method thereof, composite material and preparation method thereof

Abstract

The invention discloses a recyclable epoxy resin matrix and a preparation method thereof, and a composite material and a preparation method thereof, and relates to the technical field of composite materials. The recoverable epoxy resin matrix comprises mixed resin, a transesterification catalyst and a curing agent, the mixed resin comprises epoxy resin and thermoplastic toughening resin, and the mass of the thermoplastic toughening resin is 8-15% of the total mass of the mixed resin; the mass of the ester exchange catalyst is 3-7% of the total mass of the mixed resin; the mass ratio of the epoxy resin to the curing agent is 100: (30-70). The epoxy resin matrix disclosed by the invention has the advantages of high strength and good toughness, and the cured resin matrix can be degraded in an organic solvent, so that recycling of carbon fibers in the carbon fiber composite material is realized, and environmental pollution is reduced while the economic value of the carbon fiber composite material is greatly improved.

Description

Technical Field

[0001] The present application relates to the technical field of composite materials, and in particular to a recyclable epoxy resin matrix and a preparation method, a composite material and a preparation method. Background Art

[0002] With the rapid development of aerospace, energy, military, transportation and other fields, carbon fiber composites have been widely used due to their excellent mechanical properties and designability, among which epoxy resin-based carbon fiber composites are the most widely used. Epoxy resin-based carbon fiber composites use epoxy resin as the resin matrix and carbon fiber as the reinforcing material. They have advantages such as light weight and high strength that traditional metal materials cannot match. However, the current epoxy resin-based carbon fiber composites still have poor toughness, shorter lifespan than metal materials, inability to degrade naturally, and difficulty in recycling, which limits their further application. Summary of the invention

[0003] In order to solve the above technical problems, the present application aims to provide a recyclable epoxy resin matrix and preparation method, a composite material and preparation method. The epoxy resin matrix has remodelability and reprocessability, and the fiber material in the fiber-reinforced composite material prepared from the epoxy resin matrix can be recycled again.

[0004] According to a first aspect of the present application, there is provided a recyclable epoxy resin matrix, the recyclable epoxy resin matrix comprising a mixed resin, an ester exchange catalyst and a curing agent;

[0005] The mixed resin includes epoxy resin and thermoplastic toughening resin, and the mass of the thermoplastic toughening resin is 8-15% of the total mass of the mixed resin;

[0006] The mass of the transesterification catalyst is 3-7% of the total mass of the mixed resin;

[0007] The mass ratio of the epoxy resin to the curing agent is 100:30-70.

[0008] In some embodiments of the present application, the epoxy resin includes a combination of one or more of bisphenol A epoxy resin, bisphenol F epoxy resin, and novolac epoxy resin;

[0009] The thermoplastic toughening resin includes a combination of one or more of polyethersulfone resin, polysulfone resin, polyetheretherketone resin, polyimide resin, and polyphenylene ether resin;

[0010] The transesterification catalyst includes a combination of one or more of zinc acetylacetonate and 1,5,7-triazidebicyclo(4.4.0)dec-5-ene;

[0011] The curing agent includes a combination of one or more of trimellitic anhydride, methylcyclohexene tetracarboxylic dianhydride, tetrahydrophthalic anhydride, and phthalic anhydride.

[0012] In some embodiments of the present application, when the epoxy resin includes bisphenol A epoxy resin, bisphenol F epoxy resin and phenolic epoxy resin, the mass ratio of the bisphenol A epoxy resin, the bisphenol F epoxy resin and the phenolic epoxy resin is 3-4:1-2:4-5.

[0013] In some embodiments of the present application, when the curing agent includes trimellitic anhydride and methylcyclohexene tetracarboxylic dianhydride, the mass ratio of the trimellitic anhydride to the methylcyclohexene tetracarboxylic dianhydride is 1.0-2.0:1.

[0014] In some embodiments of the present application, when the curing agent includes trimellitic anhydride and phthalic anhydride, the mass ratio of the trimellitic anhydride to the phthalic anhydride is 2.0-3.0:1.

[0015] According to a second aspect of the present application, a method for preparing a recyclable epoxy resin matrix is ​​provided. The method for preparing a recyclable epoxy resin matrix is ​​used to prepare the recyclable epoxy resin matrix as described above. The method comprises:

[0016] Mixing the epoxy resin and the thermoplastic toughening resin under a first preset condition to obtain the mixed resin;

[0017] mixing the mixed resin and the transesterification catalyst under a second preset condition to obtain a premix;

[0018] The premix is ​​mixed with the curing agent under a third preset condition to obtain the recyclable epoxy resin matrix.

[0019] In some embodiments of the present application, the first preset condition includes: temperature of 120-160° C., time of 60-150 min;

[0020] The second preset conditions include: temperature of 80-100°C and time of 15-30min;

[0021] The third preset condition includes: temperature of 80-100° C. and time of 25-50 min.

[0022] In some embodiments of the present application, when the epoxy resin includes bisphenol A epoxy resin, bisphenol F epoxy resin, or novolac epoxy resin, before mixing the epoxy resin with the thermoplastic toughening resin under the first preset condition, the preparation method further includes:

[0023] The bisphenol A epoxy resin, the bisphenol F epoxy resin, and the novolac epoxy resin are mixed under a fourth preset condition to obtain the mixed resin.

[0024] According to the third aspect of the present application, a composite material is provided, comprising carbon fiber and the recyclable epoxy resin matrix as described above, or the recyclable epoxy resin matrix prepared by the preparation method as described above, wherein the mass of the recyclable epoxy resin matrix is ​​30-40% of the total mass of the composite material.

[0025] According to a fourth aspect of the present application, a method for preparing a composite material is provided. The method for preparing a composite material is used to prepare the composite material as described above, and the method comprises:

[0026] Covering the surface of the carbon fiber bundle with an epoxy resin matrix adhesive film, and allowing the epoxy resin matrix adhesive film to infiltrate the carbon fiber bundle under a fifth preset condition to obtain a prepreg; wherein the epoxy resin matrix adhesive film is formed by coating the recyclable epoxy resin matrix;

[0027] The prepreg is cured under a preset curing system to obtain the composite material.

[0028] The technical solution provided by this application may have the following beneficial effects:

[0029] The present application introduces an ester exchange catalyst to form dynamic covalent bonds, so that cracks in the resin matrix can be repaired under specific conditions, and the cured resin matrix can be degraded in an organic solvent to achieve the recycling and reuse of the carbon fiber in the carbon fiber composite material, thereby greatly improving the economic value of the carbon fiber composite material while reducing environmental pollution.

[0030] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0032] Figure 1 is a flow chart of a method for preparing a recyclable epoxy resin matrix according to an exemplary embodiment.

[0033] Figure 2 The present invention is a flow chart of a method for preparing a composite material according to an exemplary embodiment.

[0034] Figure 3 Graph showing the dissolution process of the composite material prepared from the recyclable epoxy resin matrix of Example 1. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme of the present application will be clearly and completely described below in combination with the embodiments of the present application and the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present application. It should be noted that, in the absence of conflict, the embodiments in the present application and the features in the embodiments can be arbitrarily combined with each other.

[0036] Since the cured epoxy resin is an insoluble and infusible highly cross-linked structure, it is difficult for its molecular chain to slip, and the material is brittle and has poor impact resistance. In addition, the cured epoxy resin cannot be melted again, and the carbon fiber cannot be recycled. As the main application areas of epoxy resin-based carbon fiber composite materials, wind power and aerospace fields produce more than 40,000 tons of waste composite materials each year. Most of the waste is buried, which causes serious harm to the soil environment and water resources. A small part of the waste is recycled by mechanical crushing and heat treatment. Short fibers, but this recycling method faces the problems of high energy consumption and high pollution, resulting in low economic value of recycled fibers. At present, chemical recycling and microwave technology are under development, but their high equipment requirements and cost issues cannot be ignored. Therefore, it is urgent to develop an efficient and convenient technology for recycling carbon fiber.

[0037] Based on this, the present application provides a recyclable epoxy resin matrix, including a mixed resin, an ester exchange catalyst and a curing agent; the mixed resin includes an epoxy resin and a thermoplastic toughening resin, the mass of the thermoplastic toughening resin is 8-15% of the total mass of the mixed resin; the mass of the ester exchange catalyst is 3-7% of the total mass of the mixed resin; the mass ratio of the epoxy resin to the curing agent is 100:30-70. The present application introduces a thermoplastic toughening resin to form an interpenetrating network polymer system with the epoxy resin, which improves the toughness of the epoxy resin matrix while improving its tensile strength. In addition, by introducing an ester exchange catalyst, a dynamic covalent bond can be formed, so that the cracks generated by the resin matrix can be repaired under specific conditions, and the resin matrix in the carbon fiber composite material made of the resin matrix can be degraded in an organic solvent to achieve the recycling and reuse of the carbon fiber, while greatly improving the economic value of the carbon fiber composite material and reducing environmental pollution. The carbon fiber composite material prepared by the epoxy resin matrix of the present application has the potential value of large-scale use and recycling of carbon fiber in scenes such as wind turbine blades and new energy battery boxes, which is conducive to increasing the added value of the product.

[0038] Some specific implementation modes described below are intended to facilitate those skilled in the art to understand the present embodiment, and the present embodiment is not limited to some specific implementation modes described below.

[0039] An exemplary embodiment of the present application provides a recyclable epoxy resin matrix, comprising a mixed resin, an ester exchange catalyst and a curing agent; the mixed resin comprises an epoxy resin and a thermoplastic toughening resin, the mass of the thermoplastic toughening resin is 8-15% of the total mass of the mixed resin; the mass of the ester exchange catalyst is 3-7% of the total mass of the mixed resin; the mass ratio of the epoxy resin to the curing agent is 100:30-70.

[0040] In this embodiment, by introducing a thermoplastic toughening resin, an interpenetrating network polymer system can be formed with the epoxy resin, which improves the toughness of the epoxy resin matrix and its tensile strength. In addition, by introducing an ester exchange catalyst, a dynamic covalent bond can be formed, so that cracks generated in the resin matrix can be repaired under specific conditions. At the same time, the resin matrix in the carbon fiber composite material made of the resin matrix can be degraded in an organic solvent to achieve the recycling and reuse of the carbon fiber, greatly improving the economic value of the carbon fiber composite material while reducing environmental pollution.

[0041] Among them, by adjusting the ratio of thermoplastic toughening resin to epoxy resin, the ratio of ester exchange catalyst to mixed resin, and the ratio of mixed resin to curing agent, the composite material made of the epoxy resin matrix can have good mechanical strength and toughness, as well as repairability and recyclability.

[0042] Exemplarily, in one embodiment, the recyclable epoxy resin matrix includes a mixed resin, an ester exchange catalyst and a curing agent; the mixed resin includes an epoxy resin and a thermoplastic toughening resin, the mass of the thermoplastic toughening resin is 8% of the total mass of the mixed resin; the mass of the ester exchange catalyst is 7% of the total mass of the mixed resin; the mass ratio of the epoxy resin to the curing agent is 100:30.

[0043] In another embodiment, the recyclable epoxy resin matrix includes a mixed resin, an ester exchange catalyst and a curing agent; the mixed resin includes an epoxy resin and a thermoplastic toughening resin, the mass of the thermoplastic toughening resin is 12% of the total mass of the mixed resin; the mass of the ester exchange catalyst is 5% of the total mass of the mixed resin; the mass ratio of the epoxy resin to the curing agent is 100:50.

[0044] In another embodiment, the recyclable epoxy resin matrix includes a mixed resin, an ester exchange catalyst and a curing agent; the mixed resin includes an epoxy resin and a thermoplastic toughening resin, the mass of the thermoplastic toughening resin is 15% of the total mass of the mixed resin; the mass of the ester exchange catalyst is 3% of the total mass of the mixed resin; the mass ratio of the epoxy resin to the curing agent is 100:70.

[0045] Wherein, the recyclable epoxy resin matrix includes the following raw materials in parts by mass:

[0046]

[0047] Exemplarily, in one embodiment, the recyclable epoxy resin matrix includes the following raw materials in parts by mass:

[0048]

[0049] In another embodiment, the recyclable epoxy resin matrix includes the following raw materials in parts by mass:

[0050]

[0051] In another embodiment, the recyclable epoxy resin matrix includes the following raw materials in parts by mass:

[0052]

[0053] In an exemplary embodiment, the epoxy resin includes a combination of one or more of bisphenol A epoxy resin, bisphenol F epoxy resin, and novolac epoxy resin.

[0054] Bisphenol A epoxy resin has good bonding properties, mechanical properties, and its cured product has good chemical corrosion resistance and weather resistance. Bisphenol F epoxy resin has lower viscosity than bisphenol A epoxy resin, so that it has better impregnation and fluidity. Novolac epoxy resin combines the characteristics of novolac epoxy resin and epoxy resin, and has good strength, hardness, adhesion, heat resistance and lower curing shrinkage. In the present embodiment, epoxy resin can adopt one or more compositions in bisphenol A epoxy resin, bisphenol F epoxy resin, novolac epoxy resin, so that cured product obtains better overall performance.

[0055] Wherein, when the epoxy resin includes bisphenol A epoxy resin, bisphenol F epoxy resin and novolac epoxy resin, the mass ratio of bisphenol A epoxy resin, bisphenol F epoxy resin and novolac epoxy resin is 3-4:1-2:4-5. Exemplarily, the mass ratio of bisphenol A epoxy resin, bisphenol F epoxy resin and novolac epoxy resin is 3:1:4, 3.4:1.5:4.5 or 4:2:5.

[0056] In an exemplary embodiment, the thermoplastic toughening resin includes a combination of one or more of polyethersulfone resin, polysulfone resin, polyetheretherketone resin, polyimide resin, and polyphenylene ether resin.

[0057] The polyethersulfone resin (PES), polysulfone resin (PSF), polyetheretherketone resin (PEEK), polyimide resin (PI), and polyphenylene oxide resin (PPO) in this embodiment are special engineering plastics with excellent heat resistance, impact resistance, and processing performance. Using polyethersulfone resin, polysulfone resin, polyetheretherketone resin, polyimide resin, and polyphenylene oxide resin as thermoplastic toughening resins can have a good toughening effect on the resin matrix to increase its application range.

[0058] In an exemplary embodiment, the transesterification catalyst includes a combination of one or more of zinc acetylacetonate and 1,5,7-triazidobicyclo(4.4.0)dec-5-ene.

[0059] In this embodiment, the transesterification catalyst may be zinc acetylacetonate and / or 1,5,7-triazidebicyclo(4.4.0)dec-5-ene (TBD). The above transesterification catalysts all have high catalytic efficiency and can promote the transesterification reaction.

[0060] In an exemplary embodiment, the curing agent includes a combination of one or more of trimellitic anhydride, methylcyclohexene tetracarboxylic dianhydride, tetrahydrophthalic anhydride, and phthalic anhydride.

[0061] The epoxy resin cured material cured by trimellitic anhydride (TMA) has excellent thermal stability and high strength and hardness. The epoxy resin cured material cured by methylcyclohexene tetraacid dianhydride (MCDEA) has good bonding properties and glass transition temperature, and can be applied to high-strength composite materials. The epoxy resin cured material cured by tetrahydrophthalic anhydride (THPA) has good flexibility and weather resistance, and the curing reaction exothermic heat is low, which is conducive to controlling the temperature in the curing process and reducing thermal stress. Phthalic anhydride (PA) has lower cost, better compatibility with other epoxy resins, and its cured material has good bonding properties. In the present embodiment, the curing agent can select one or more compositions thereof to obtain better comprehensive properties for its cured material.

[0062] Wherein, when the curing agent includes trimellitic anhydride and methylcyclohexene tetracarboxylic dianhydride, the mass ratio of trimellitic anhydride to methylcyclohexene tetracarboxylic dianhydride is 1.0-2.0: 1. Exemplarily, the mass ratio of trimellitic anhydride to methylcyclohexene tetracarboxylic dianhydride is 1.0: 1, 1.5: 1 or 2.0: 1.

[0063] When the curing agent includes trimellitic anhydride and phthalic anhydride, the mass ratio of trimellitic anhydride to phthalic anhydride is 2.0-3.0: 1. For example, the mass ratio of trimellitic anhydride to phthalic anhydride is 2.0: 1, 2.5: 1 or 3.0: 1.

[0064] like Figure 1 As shown, an exemplary embodiment of the present application provides a method for preparing a recyclable epoxy resin matrix, comprising:

[0065] S110, mixing the epoxy resin and the thermoplastic toughening resin under the first preset condition to obtain a mixed resin.

[0066] In step S110, epoxy resin and thermoplastic toughening resin are uniformly mixed at a first preset temperature to obtain a mixed resin; wherein the temperature in the first preset condition can be set according to the melting point of the epoxy resin.

[0067] S120, mixing the mixed resin and the transesterification catalyst under a second preset condition to obtain a premix.

[0068] In step S120, the mixed resin and the transesterification catalyst are mixed under a second preset condition so that the mixed resin and the transesterification catalyst are uniformly mixed to obtain a premix.

[0069] S130, mixing the premix with the curing agent under a third preset condition to obtain a recyclable epoxy resin matrix.

[0070] In step S130, the premix and the curing agent are uniformly mixed under a third preset condition to obtain a recyclable epoxy resin matrix; wherein the temperature of the third preset condition can be set below the curing temperature of the epoxy resin to avoid premature curing of the epoxy resin matrix.

[0071] In an exemplary embodiment, the first preset conditions include: a temperature of 120-160° C. and a time of 60-150 min;

[0072] The second preset conditions include: temperature of 80-100°C and time of 15-30min;

[0073] The third preset condition includes: temperature of 80-100° C. and time of 25-50 min.

[0074] Exemplarily, in one embodiment, the first preset condition includes: temperature is 120° C., time is 150 min;

[0075] The second preset conditions include: temperature is 80°C, time is 30 minutes;

[0076] The third preset condition includes: temperature is 80° C., and time is 50 min.

[0077] In another embodiment, the first preset condition includes: temperature is 140° C., time is 100 min;

[0078] The second preset conditions include: temperature is 90°C, time is 20 minutes;

[0079] The third preset condition includes: temperature is 90° C., and time is 35 min.

[0080] In another embodiment, the first preset condition includes: temperature is 160° C., time is 60 min;

[0081] The second preset conditions include: temperature is 100°C, time is 15 minutes;

[0082] The third preset condition includes: temperature is 100° C., and time is 25 min.

[0083] In an exemplary embodiment, when the epoxy resin includes bisphenol A epoxy resin, bisphenol F epoxy resin, or novolac epoxy resin, before mixing the epoxy resin with the thermoplastic toughening resin under the first preset condition in step S110, the preparation method further includes:

[0084] Bisphenol A epoxy resin, bisphenol F epoxy resin and novolac epoxy resin are mixed under a fourth preset condition to obtain a mixed resin.

[0085] In this embodiment, bisphenol A epoxy resin, bisphenol F epoxy resin, and phenolic epoxy resin are first mixed and stirred under the fourth preset condition to improve the uniformity of the raw material mixing; wherein the fourth preset condition can be, for example, a temperature of 80-100°C and a time of 15-30min.

[0086] Exemplarily, in one embodiment, the fourth preset condition is: temperature is 80° C., and time is 30 min.

[0087] In another embodiment, the fourth preset condition is: temperature is 90° C., and time is 20 min.

[0088] In another embodiment, the fourth preset condition is: temperature is 100° C., and time is 15 minutes.

[0089] An exemplary embodiment of the present application provides a composite material, comprising carbon fibers and the recyclable epoxy resin matrix as described in the above embodiment, wherein the mass of the recyclable epoxy resin matrix accounts for 30-40% of the total mass of the composite material.

[0090] In this embodiment, by controlling the ratio of carbon fiber to epoxy resin matrix, the epoxy resin matrix can provide good bonding performance for the carbon fiber, and the composite material has good mechanical strength and avoids the occurrence of delamination.

[0091] Exemplarily, the mass of the recyclable epoxy resin matrix is ​​30%, 35% or 40% of the total mass of the composite material.

[0092] like Figure 2 As shown, an exemplary embodiment of the present application provides a method for preparing a composite material, comprising:

[0093] S210, coating the surface of the carbon fiber bundle with an epoxy resin matrix adhesive film, and allowing the epoxy resin matrix adhesive film to impregnate the carbon fiber bundle under a fifth preset condition to obtain a prepreg; wherein the epoxy resin matrix adhesive film is formed by coating a recyclable epoxy resin matrix.

[0094] In step S210, the epoxy resin matrix adhesive film can be formed by coating with a coating steel roller, wherein the temperature of the coating steel roller can be set at 75±5°C; the weight of the epoxy resin matrix adhesive film can be 50±1g / m 2 .

[0095] The epoxy resin matrix film is applied to the surface of the carbon fiber bundle. Under the fifth preset condition, the epoxy resin matrix film is impregnated with the carbon fiber bundle using an impregnation roller group, wherein the impregnation roller group temperature is 100-115°C, the impregnation speed is 2-6m / min, and the fiber weight is 191±3g / m 2 .

[0096] S220, curing the prepreg under a preset curing system to obtain a composite material.

[0097] In step S220, the preset curing system can be one-stage curing or multi-stage curing. The curing molding by multi-stage curing can avoid the aging of components caused by the large temperature difference between the inside and outside, which is conducive to improving the quality of the product. Among them, the multi-stage curing can be two-stage curing, three-stage curing, four-stage curing, etc. For example, the three-stage curing system includes: keeping warm at 80°C for 1 hour for the first curing; keeping warm at 125°C for 1 hour for the second curing; keeping warm at 180°C for 1 hour for the third curing.

[0098] The specific implementation methods of the present application are further described below in conjunction with preferred embodiments, and examples of preferred value ranges of each component in the recyclable epoxy resin matrix provided in the present application are explained in detail.

[0099] Preferred Example 1

[0100] A recyclable epoxy resin matrix comprises a mixed resin, an ester exchange catalyst and a curing agent; the mixed resin comprises an epoxy resin and a thermoplastic toughening resin, the mass of the thermoplastic toughening resin is 8-15% of the total mass of the mixed resin; the mass of the ester exchange catalyst is 3-7% of the total mass of the mixed resin; the mass ratio of the epoxy resin to the curing agent is 100:30-70;

[0101] Wherein, the epoxy resin includes a combination of one or more of bisphenol A epoxy resin, bisphenol F epoxy resin, and novolac epoxy resin;

[0102] The thermoplastic toughening resin includes a combination of one or more of polyethersulfone resin, polysulfone resin, polyetheretherketone resin, polyimide resin, and polyphenylene ether resin;

[0103] The transesterification catalyst includes a combination of one or more of zinc acetylacetonate and 1,5,7-triazidobicyclo(4.4.0)dec-5-ene;

[0104] The curing agent includes a combination of one or more of trimellitic anhydride, methylcyclohexene tetracarboxylic anhydride, tetrahydrophthalic anhydride, and phthalic anhydride.

[0105] Preferred Example 2

[0106] A recyclable epoxy resin matrix comprises a mixed resin, an ester exchange catalyst and a curing agent; the mixed resin comprises an epoxy resin and a thermoplastic toughening resin, the mass of the thermoplastic toughening resin is 8-15% of the total mass of the mixed resin; the mass of the ester exchange catalyst is 3-7% of the total mass of the mixed resin; the mass ratio of the epoxy resin to the curing agent is 100:30-70;

[0107] Wherein, when the epoxy resin comprises bisphenol A epoxy resin, bisphenol F epoxy resin and novolac epoxy resin, the mass ratio of bisphenol A epoxy resin, bisphenol F epoxy resin and novolac epoxy resin is 3-4:1-2:4-5;

[0108] The thermoplastic toughening resin includes a combination of one or more of polyethersulfone resin, polysulfone resin, polyetheretherketone resin, polyimide resin, and polyphenylene ether resin;

[0109] The transesterification catalyst includes a combination of one or more of zinc acetylacetonate and 1,5,7-triazidobicyclo(4.4.0)dec-5-ene;

[0110] When the curing agent includes trimellitic anhydride and methylcyclohexene tetracarboxylic dianhydride, the mass ratio of trimellitic anhydride to methylcyclohexene tetracarboxylic dianhydride is 1.0-2.0:1.

[0111] Preferred Example 3

[0112] A recyclable epoxy resin matrix comprises a mixed resin, an ester exchange catalyst and a curing agent; the mixed resin comprises an epoxy resin and a thermoplastic toughening resin, the mass of the thermoplastic toughening resin is 8-15% of the total mass of the mixed resin; the mass of the ester exchange catalyst is 3-7% of the total mass of the mixed resin; the mass ratio of the epoxy resin to the curing agent is 100:30-70;

[0113] Wherein, when the epoxy resin comprises bisphenol A epoxy resin, bisphenol F epoxy resin and novolac epoxy resin, the mass ratio of bisphenol A epoxy resin, bisphenol F epoxy resin and novolac epoxy resin is 3-4:1-2:4-5;

[0114] The thermoplastic toughening resin includes a combination of one or more of polyethersulfone resin, polysulfone resin, polyetheretherketone resin, polyimide resin, and polyphenylene ether resin;

[0115] The transesterification catalyst includes a combination of one or more of zinc acetylacetonate and 1,5,7-triazidobicyclo(4.4.0)dec-5-ene;

[0116] When the curing agent includes trimellitic anhydride and phthalic anhydride, the mass ratio of trimellitic anhydride to phthalic anhydride is 2.0-3.0:1.

[0117] Preferred Example 4

[0118] A recyclable epoxy resin matrix comprises a mixed resin, an ester exchange catalyst and a curing agent; the mixed resin comprises an epoxy resin and a thermoplastic toughening resin, the mass of the thermoplastic toughening resin is 12-15% of the total mass of the mixed resin; the mass of the ester exchange catalyst is 4-5% of the total mass of the mixed resin; the mass ratio of the epoxy resin to the curing agent is 100:50-60;

[0119] Wherein, when the epoxy resin comprises bisphenol A epoxy resin, bisphenol F epoxy resin and novolac epoxy resin, the mass ratio of bisphenol A epoxy resin, bisphenol F epoxy resin and novolac epoxy resin is 3-4:1-2:4-5;

[0120] The thermoplastic toughening resin includes a combination of one or more of polyethersulfone resin, polysulfone resin, polyetheretherketone resin, polyimide resin, and polyphenylene ether resin;

[0121] The transesterification catalyst includes a combination of one or more of zinc acetylacetonate and 1,5,7-triazidobicyclo(4.4.0)dec-5-ene;

[0122] When the curing agent includes trimellitic anhydride and phthalic anhydride, the mass ratio of trimellitic anhydride to phthalic anhydride is 2.0-3.0:1.

[0123] In order to more clearly explain the technical solution of the present application, the present application lists specific embodiments of the recyclable epoxy resin matrix, and the beneficial effects of selecting the above-mentioned range of the content of each component will be explained by giving specific experimental data through specific embodiments.

[0124] Example

[0125] Unless otherwise specified, the raw materials in the following examples are all commercially available.

[0126] Among them, the epoxy resin adopts liquid biphotofunctional bisphenol A epoxy resin, bisphenol F epoxy resin and phenolic epoxy resin.

[0127] Embodiment 1: A method for preparing a recyclable epoxy resin matrix, comprising the following steps:

[0128] (1) Bisphenol A epoxy resin, bisphenol F epoxy resin and novolac epoxy resin in a weight ratio of 3:2:5 were mixed and stirred at 90° C. for 20 minutes to obtain an epoxy resin mixture.

[0129] (2) The epoxy resin mixture and the polyethersulfone thermoplastic toughening resin are mixed and stirred at a temperature of 150° C. for 80 minutes to obtain a mixed resin, wherein the mass of the thermoplastic toughening resin is 8% of the total mass of the mixed resin.

[0130] (3) The mixed resin and the zinc acetylacetonate transesterification catalyst were mixed and stirred at 90° C. for 20 minutes to obtain a premix, wherein the mass of the transesterification catalyst was 5% of the total mass of the mixed resin.

[0131] (4) The premix and the curing agent are mixed and stirred at a temperature of 90° C. and vacuum degassed for 40 minutes to obtain a recyclable epoxy resin matrix. The curing agent is a mixture of trimellitic anhydride and methylcyclohexene tetracarboxylic dianhydride in a mass ratio of 1.5:1, and the mass ratio of the epoxy resin to the curing agent is 100:50.

[0132] In this embodiment, based on 100 kg of the mixed resin, the mass of the thermoplastic toughening resin is 8 kg, the mass of the epoxy resin mixture is 92 kg, the mass of the transesterification catalyst is 5 kg, and the mass of the curing agent is 46 kg.

[0133] In order to more clearly explain the technical solution of the present application, the present application also lists Examples 2-8 of the preparation method of the recyclable epoxy resin matrix, wherein the formulas of Examples 2-8 are shown in Table 1.

[0134] Table 1 shows a specific embodiment of the recyclable epoxy resin matrix in the present application. It should be noted that, except for the parameters listed in Table 1, other parameters of Examples 2-8 are substantially the same as those of Example 1.

[0135] Among them, the ratio C1 in Table 1 is the mass ratio of bisphenol A epoxy resin, bisphenol F epoxy resin, and novolac epoxy resin.

[0136] The ratio C2 is the mass percentage of the thermoplastic resin to the total mass of the mixed resin.

[0137] The ratio C3 is the mass percentage of the transesterification catalyst to the total mass of the mixed resin.

[0138] The ratio C4 is the mass ratio of the epoxy resin mixture to the curing agent.

[0139] The ratio C5 is the mass ratio of trimellitic anhydride to methylcyclohexene tetracarboxylic dianhydride.

[0140] The ratio C6 is the mass of trimellitic anhydride and phthalic anhydride.

[0141] Table 1 Recipe of the recyclable epoxy resin matrix of the embodiment

[0142]

[0143] Comparative Example

[0144] Comparative Example 1: A method for preparing an epoxy resin matrix, comprising the following steps:

[0145] (1) Bisphenol A epoxy resin, bisphenol F epoxy resin and novolac epoxy resin in a weight ratio of 3:2:5 were mixed and stirred at 90° C. for 20 minutes to obtain an epoxy resin mixture.

[0146] (2) The epoxy resin mixture and the curing agent are mixed and stirred at a temperature of 90° C. and vacuum degassed for 40 minutes to obtain an epoxy resin matrix. The curing agent is a mixture of trimellitic anhydride and methylcyclohexene tetracarboxylic dianhydride in a weight ratio of 6:4. The mass ratio of the epoxy resin mixture to the curing agent is 100:50.

[0147] Performance Testing

[0148] 1. Fracture toughness: The epoxy resin matrix was prepared by the methods of the embodiment and the comparative example, and the epoxy resin matrix was kept at 80°C for 1 hour for the first curing; kept at 125°C for 1 hour for the second curing; and kept at 180°C for 1 hour for the third curing to obtain sample A. The fracture toughness of sample A was tested, and the test results are recorded in Table 2.

[0149] Table 2 Fracture toughness test table of epoxy resin matrix samples of the embodiment and comparative example

[0150] project <![CDATA[Fracture toughness, MPa / m 1 / 2 > Example 1 0.98 Example 2 0.88 Example 3 0.95 Example 4 1.00 Example 5 1.02 Example 6 1.11 Example 7 1.23 Example 8 1.17 Comparative Example 1 0.56

[0151] It can be seen from the data in Table 1 and Table 2 as well as Example 1 and Comparative Example 1 that the epoxy resin matrix prepared by the examples of the present application has good fracture toughness, indicating that the addition of thermoplastic toughening resin can significantly improve the impact toughness of the epoxy resin matrix. When the amount of thermoplastic toughening resin, the amount of transesterification catalyst, the mass ratio of each epoxy resin, the mass ratio of epoxy resin mixture to curing agent, and the mass ratio of each curing agent change, the toughness of the epoxy resin matrix will be affected to a certain extent. Among them, the epoxy resin matrix of Examples 4-8 has a higher fracture toughness, indicating that when the mass of the thermoplastic toughening resin accounts for 10-15% of the total mass of the mixed resin, the mass of the transesterification catalyst accounts for 4-7% of the total mass of the mixed resin, and the mass ratio of the epoxy resin mixture to the curing agent is 100:35-70, the epoxy resin matrix can maintain a higher toughness. Further, the epoxy resin matrix of Examples 6-7 has better fracture toughness, indicating that when the mass of the thermoplastic toughening resin accounts for 12-15% of the total mass of the mixed resin, the mass of the transesterification catalyst accounts for 4-5% of the total mass of the mixed resin, and the mass ratio of the epoxy resin mixture to the curing agent is 100:50-60, the epoxy resin matrix can maintain higher toughness. In addition, when the epoxy resin mixture is compounded with bisphenol A epoxy resin, bisphenol F epoxy resin and phenolic resin in a mass ratio of 3-4:1:4-5, and the curing agent is compounded with trimellitic anhydride and phthalic anhydride in a mass ratio of 3.0:1 or trimellitic anhydride and methylcyclohexene tetracarboxylic anhydride in a mass ratio of 2.0:1, it is also beneficial to improve the impact toughness of the epoxy resin matrix.

[0152] 2. Recyclability: The epoxy resin matrix prepared in Example 1 was impregnated with carbon fiber to obtain a prepreg; the prepreg was kept at 80°C for 1 hour for the first curing; kept at 125°C for 1 hour for the second curing; kept at 180°C for 1 hour for the third curing to obtain sample B. Figure 3 As shown, after sample B undergoes step ① (maintaining 180°C / 1h in ethylene glycol solvent), step ② (maintaining 180°C / 2h in ethylene glycol solvent), and step ③ (filtering the solvent), the carbon fiber material can be completely separated, thereby achieving the recycling and reuse of the carbon fiber.

[0153] In summary, the epoxy resin matrix prepared by the method of the present application not only has good toughness, but the fiber-reinforced composite material prepared therefrom also has recyclable properties, thereby realizing the recycling and reuse of carbon fibers.

[0154] It should be noted that, in this article, the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.

[0155] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application is described in detail with reference to the above embodiments, a person skilled in the art should understand that the technical solutions described in the above embodiments can still be modified, or some of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A recyclable epoxy resin matrix, characterized in that: The recyclable epoxy resin matrix includes a mixed resin, an ester exchange catalyst and a curing agent; The mixed resin includes epoxy resin and thermoplastic toughening resin, and the mass of the thermoplastic toughening resin is 8-15% of the total mass of the mixed resin; The mass of the transesterification catalyst is 3-7% of the total mass of the mixed resin; The mass ratio of the epoxy resin to the curing agent is 100:30-70.

2. The recyclable epoxy resin matrix according to claim 1, characterized in that: The epoxy resin includes a combination of one or more of bisphenol A epoxy resin, bisphenol F epoxy resin, and novolac epoxy resin; The thermoplastic toughening resin includes a combination of one or more of polyethersulfone resin, polysulfone resin, polyetheretherketone resin, polyimide resin, and polyphenylene ether resin; The transesterification catalyst includes a combination of one or more of zinc acetylacetonate and 1,5,7-triazidebicyclo(4.4.0)dec-5-ene; The curing agent includes a combination of one or more of trimellitic anhydride, methylcyclohexene tetracarboxylic dianhydride, tetrahydrophthalic anhydride, and phthalic anhydride.

3. The recyclable epoxy resin matrix according to claim 2, characterized in that: When the epoxy resin comprises bisphenol A epoxy resin, bisphenol F epoxy resin and novolac epoxy resin, the mass ratio of the bisphenol A epoxy resin, the bisphenol F epoxy resin and the novolac epoxy resin is 3-4:1-2:4-5.

4. The recyclable epoxy resin matrix according to claim 2, characterized in that: When the curing agent comprises trimellitic anhydride and methylcyclohexene tetracarboxylic dianhydride, the mass ratio of the trimellitic anhydride to the methylcyclohexene tetracarboxylic dianhydride is 1.0-2.0:

1.

5. The recyclable epoxy resin matrix according to claim 2, characterized in that: When the curing agent comprises trimellitic anhydride and phthalic anhydride, the mass ratio of the trimellitic anhydride to the phthalic anhydride is 2.0-3.0:

1.

6. A method for preparing a recyclable epoxy resin matrix, characterized in that: The preparation method of the recyclable epoxy resin matrix is ​​used to prepare the recyclable epoxy resin matrix according to any one of claims 1 to 5, and the preparation method comprises: Mixing the epoxy resin and the thermoplastic toughening resin under a first preset condition to obtain the mixed resin; mixing the mixed resin and the transesterification catalyst under a second preset condition to obtain a premix; The premix is ​​mixed with the curing agent under a third preset condition to obtain the recyclable epoxy resin matrix.

7. The preparation method according to claim 6, characterized in that: The first preset conditions include: temperature of 120-160°C and time of 60-150min; The second preset conditions include: temperature of 80-100°C and time of 15-30min; The third preset condition includes: temperature of 80-100° C. and time of 25-50 min.

8. The preparation method according to claim 6, characterized in that: When the epoxy resin includes bisphenol A epoxy resin, bisphenol F epoxy resin, or novolac epoxy resin, before mixing the epoxy resin with the thermoplastic toughening resin under the first preset condition, the preparation method further includes: The bisphenol A epoxy resin, the bisphenol F epoxy resin, and the novolac epoxy resin are mixed under a fourth preset condition to obtain the mixed resin.

9. A composite material, characterized in that: The composite material comprises carbon fiber and a recyclable epoxy resin matrix as described in any one of claims 1 to 5, or a recyclable epoxy resin matrix prepared by the preparation method as described in any one of claims 6 to 8, wherein the mass of the recyclable epoxy resin matrix is ​​30-40% of the total mass of the composite material.

10. A method for preparing a composite material, characterized in that: The method for preparing the composite material is used to prepare the composite material according to claim 9, and the method for preparing the composite material comprises: Covering the surface of the carbon fiber bundle with an epoxy resin matrix adhesive film, and allowing the epoxy resin matrix adhesive film to infiltrate the carbon fiber bundle under a fifth preset condition to obtain a prepreg; wherein the epoxy resin matrix adhesive film is formed by coating the recyclable epoxy resin matrix; The prepreg is cured under a preset curing system to obtain the composite material.

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