An epoxy resin solid plastic and a method for producing the same

Abstract

The application provides an epoxy resin solid plastic body and a preparation method thereof, and belongs to the technical field of thermosetting epoxy resin modification. The epoxy resin solid plastic body is made of an epoxy resin, an anhydride curing agent, a curing accelerator and a combined transesterification catalyst, wherein the mass ratio of the epoxy resin, the anhydride curing agent, the curing accelerator and the combined transesterification catalyst is 30-50:30-50:0.1-2:1-10; the combined transesterification catalyst is composed of a main catalyst and an auxiliary catalyst, wherein the mass ratio of the main catalyst and the auxiliary catalyst is 1:0.1-0.5. The epoxy resin solid plastic body prepared by the application not only has the excellent performance of traditional thermosetting epoxy resin, but also has the advantages of recyclability, repeatable molding and degradability.

Description

Technical Field

[0001] This invention relates to the field of thermosetting epoxy resin modification technology, and in particular to an epoxy resin solid and its preparation method. Background Technology

[0002] In the field of materials science, thermosetting epoxy resins are widely used in numerous fields such as electronics, wind turbine blades, aerospace, and automotive manufacturing due to their excellent physical and chemical properties, such as high strength, high heat resistance, good electrical insulation, and chemical stability. However, while the three-dimensional cross-linked structure of thermosetting epoxy resins endows them with outstanding performance, it also leads to the problem of difficulty in recycling and reusing them after their service life. Traditional recycling methods, such as mechanical recycling and pyrolysis recycling, often suffer from drawbacks such as low efficiency, high energy consumption, and significant environmental pollution. Moreover, the performance of the recycled epoxy resin materials is severely degraded, failing to meet the requirements for recycling.

[0003] In recent years, with the growing popularity of sustainable development, circular economy, and environmental protection concepts, researchers have begun to seek more environmentally friendly and efficient methods for recycling thermosetting epoxy resins. Among these methods, dynamic transesterification, as a potential reversible crosslinking reaction, has attracted widespread attention. In 2011, Leibler et al. in France added zinc acetylacetone to bisphenol A epoxy resin and cured it using unsaturated binary / tercarboxylic acids, discovering the dynamic covalent bond exchange mechanism and defining the T... v (Topological transition temperature) Below this temperature, the resin exhibits the characteristics of a traditional thermosetting resin. Above this temperature, a dynamic exchange reaction occurs, and the material exhibits the characteristics of a thermoplastic resin, thus endowing it with recyclable and reusable properties. Leibler et al. named this material, which combines thermosetting and thermoplastic properties, "vitrimer," which is translated into Chinese as a glass-like polymer or solid plastic material based on its physical meaning. Based on the different dynamic covalent bonds in the crosslinked network, solid plastic materials based on ester bonds, imine bonds, disulfide bonds, and borate ester bonds have been developed.

[0004] Although researchers have developed epoxy resins based on the various dynamic bond systems mentioned above, most of them have excessively low glass transition temperatures and insufficient mechanical strength to meet application requirements, leaving a significant gap before true industrialization and commercialization. Since the most commonly used amine-cured epoxy resins do not contain covalent bonds with dynamic exchange potential, most epoxy resins containing dynamically exchangeable ester bonds are currently thermosetting epoxy resins based on epoxy anhydride systems. Bisphenol A and bisphenol F type epoxy resins account for the largest proportion, and methyltetrahydrophthalic anhydride is the most widely used anhydride curing agent. These epoxy resins are also widely used in the liquid molding of fiber-reinforced composites due to their low viscosity, such as infusion, winding, pultrusion, and wet molding. Typical ester bond dynamic exchange catalysts include zinc acetylacetonate, zinc acetate, 1,5,7-triazine-bis(4,4,0)dec-5-ene (TBD), triethanolamine, triphenylphosphine, titanates, and imidazole compounds. However, these catalysts, whether used alone or in combination, generally suffer from low catalytic efficiency and slow relaxation rates. This is especially true when anhydride-cured epoxy resin systems contain curing accelerators; the chemical interference between the aforementioned dynamic ester exchange catalysts and the curing accelerators reduces the activity of the ester exchange catalysts or renders them completely ineffective. Therefore, researching an epoxy resin solid and its preparation method, employing a combined ester exchange catalyst capable of effectively catalyzing dynamic ester exchange reactions even in the presence of curing accelerators, is of significant importance. Summary of the Invention

[0005] The purpose of this invention is to provide an epoxy resin solid and its preparation method, so as to solve the problem that traditional thermosetting epoxy resins are difficult to recycle and cannot be repeatedly molded in the prior art.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] This invention provides an epoxy resin solidified body, which is made of epoxy resin, an anhydride curing agent, a curing accelerator, and a combined transesterification catalyst, wherein the mass ratio of epoxy resin, anhydride curing agent, curing accelerator, and combined transesterification catalyst is 30-50:30-50:0.1-2:1-10; the combined transesterification catalyst is composed of a main catalyst and a co-catalyst, wherein the mass ratio of the main catalyst and the co-catalyst is 1:0.1-0.5.

[0008] Preferably, the epoxy resin comprises glycidyl ether epoxy resin, glycidyl ester epoxy resin, glycidyl amine epoxy resin, alicyclic epoxy resin, or epoxidized olefin epoxy resin.

[0009] Preferably, the anhydride curing agent comprises aromatic anhydride, aliphatic anhydride, alicyclic anhydride or halogen-containing anhydride; the curing accelerator comprises one or more of 2,4,6-tris(dimethylaminomethyl)phenol, chromium octanoate, benzyl dimethylamine, imidazole and metal salt of acetylacetone.

[0010] Preferably, the main catalyst comprises one or more of zinc methacrylate, zinc acetylacetone, zinc acetate, triphenylphosphine, and titanate; the co-catalyst comprises benzyl quaternary ammonium salt or alkyl quaternary ammonium salt.

[0011] Preferably, the benzyl quaternary ammonium salt has the chemical formula C0. n H 2n-4 R1N, where n is an integer greater than or equal to 10, and R1 is F, Cl, Br, or I; the chemical formula of the alkyl quaternary ammonium salt is C m H 2m+4 R2N, where m is an integer greater than or equal to 4, and R2 is F, Cl, Br, or I.

[0012] This invention provides a method for preparing the epoxy resin solidified body described above, comprising the following steps:

[0013] (1) Mix the co-catalyst, the main catalyst and the acid anhydride curing agent to obtain a mixed solution;

[0014] (2) After mixing epoxy resin, curing accelerator and the mixed solution of step (1), degassing and curing are carried out in sequence to obtain epoxy resin solid plastic.

[0015] Preferably, in step (1), the co-catalyst and the anhydride curing agent are first mixed, and then the main catalyst is added.

[0016] Preferably, in step (2), the degassing speed is 1200-1800 rpm and the degassing time is 2-6 min.

[0017] Preferably, in step (2), the curing process includes a first curing, a second curing, and a third curing.

[0018] Preferably, the first curing temperature is 80-100℃ and the first curing time is 0.5-1.5h; the second curing temperature is 130-150℃ and the second curing time is 0.5-1.5h; the third curing temperature is 190-210℃ and the third curing time is 0.5-1.5h.

[0019] The beneficial effects of this invention are:

[0020] (1) Compared with traditional single-type transesterification catalysts, the present invention uses a combined transesterification catalyst to prepare epoxy resin solids. The combined transesterification catalyst consists of a main catalyst and a co-catalyst. By controlling the mass ratio of the main catalyst and the co-catalyst, the catalytic efficiency of the combined transesterification catalyst is significantly improved. In particular, it can effectively catalyze dynamic transesterification reactions when a curing accelerator is contained.

[0021] (2) The epoxy resin solid body prepared by the present invention not only has the excellent properties of traditional thermosetting epoxy resin, but also has the advantages of being recyclable, re-moldingable, and degradable, providing a new way for the recycling and reuse of thermosetting epoxy resin materials and having broad application prospects. Attached Figure Description

[0022] Figure 1 Stress relaxation curves of the epoxy resin solids prepared in Examples 1-3 and Comparative Examples 1-6 at 250°C.

[0023] Figure 2 The dynamic thermomechanical analysis diagrams are shown for the epoxy resin solid plastic of Example 1 and the dynamic thermomechanical analysis diagrams of the samples after repeated molding.

[0024] Figure 3 This is a diagram of a repeat molding experiment of the epoxy resin solidified body in Example 1;

[0025] Figure 4 This is a degradation experiment diagram of the epoxy resin solidified body in Example 1. Detailed Implementation

[0026] This invention provides an epoxy resin solidified body, which is made of epoxy resin, an anhydride curing agent, a curing accelerator, and a combined transesterification catalyst, wherein the mass ratio of epoxy resin, anhydride curing agent, curing accelerator, and combined transesterification catalyst is 30-50:30-50:0.1-2:1-10; the combined transesterification catalyst is composed of a main catalyst and a co-catalyst, wherein the mass ratio of the main catalyst and the co-catalyst is 1:0.1-0.5.

[0027] In this invention, the mass ratio of the epoxy resin, acid anhydride curing agent, curing accelerator, and combined transesterification catalyst is preferably 35-45:35-45:0.5-1.5:1.5-8, more preferably 40-42:36-40:0.5-0.8:1.64-5; the mass ratio of the main catalyst to the co-catalyst is preferably 1:0.2-0.4, more preferably 1:0.3.

[0028] In this invention, the mass ratio of the main catalyst to the co-catalyst has good catalytic efficiency within a certain range, while a decrease or increase in the mass ratio will lead to a decrease in catalytic efficiency.

[0029] In this invention, the epoxy resin comprises glycidyl ether epoxy resin, glycidyl ester epoxy resin, glycidyl amine epoxy resin, alicyclic epoxy resin, or epoxidized olefin epoxy resin, preferably glycidyl ether epoxy resin, glycidyl ester epoxy resin, or glycidyl amine epoxy resin, and more preferably glycidyl ether epoxy resin or glycidyl ester epoxy resin.

[0030] In this invention, the glycidyl ether epoxy resin is preferably bisphenol A type epoxy resin, bisphenol F type epoxy resin, or bisphenol S type epoxy resin, more preferably bisphenol A type epoxy resin; the glycidyl ester epoxy resin is preferably diglycidyl phthalate, tetrahydrodiglycidyl phthalate, or trimellitic acid triglycidyl ester, more preferably diglycidyl phthalate; the glycidyl amine epoxy resin is preferably cyanuric acid epoxy resin or p-aminophenol epoxy resin, more preferably p-aminophenol epoxy resin; the alicyclic epoxy resin is preferably dicyclopentadiene dioxide epoxy resin or dicyclopentenyl dioxide ether, more preferably dicyclopentenyl dioxide ether; and the epoxidized olefin epoxy resin is preferably epoxidized polybutadiene.

[0031] In this invention, the anhydride curing agent comprises aromatic anhydrides, aliphatic anhydrides, alicyclic anhydrides, or halogen-containing anhydrides; the aromatic anhydride is preferably phthalic anhydride, trimellitic anhydride, or pyromellitic dianhydride; the aliphatic anhydride is preferably polyadipic anhydride, polyazelic anhydride, or polyfumaric anhydride; the alicyclic anhydride is preferably methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic anhydride, or glutaric anhydride, more preferably methyltetrahydrophthalic anhydride; the halogen-containing anhydride is preferably hexachloromethyltetrahydrophthalic anhydride or 1,4,5,6-tetrabromophthalic anhydride.

[0032] In this invention, the curing accelerator comprises one or more of 2,4,6-tris(dimethylaminomethyl)phenol, chromium octanoate, benzyl dimethylamine, imidazole, and metal salts of acetylacetone, preferably one or more of 2,4,6-tris(dimethylaminomethyl)phenol, chromium octanoate, and benzyl dimethylamine, and more preferably 2,4,6-tris(dimethylaminomethyl)phenol.

[0033] In this invention, the main catalyst comprises one or more of zinc methacrylate, zinc acetylacetone, zinc acetate, triphenylphosphine, and titanate, preferably one or more of zinc methacrylate, zinc acetylacetone, and zinc acetate, and more preferably zinc methacrylate; the co-catalyst comprises benzyl quaternary ammonium salt or alkyl quaternary ammonium salt.

[0034] In this invention, the chemical formula of the benzyl quaternary ammonium salt is C. n H 2n-4 R1N, where n is an integer greater than or equal to 10, preferably 10, 13, 16, 19, 22, or 25; R1 is F, Cl, Br, or I, preferably Cl or Br; the chemical formula of the alkyl quaternary ammonium salt is C m H 2m+4 R2N, where m is an integer greater than or equal to 4, preferably 4, 8, 12, 16, 20, or 24, and R2 is F, Cl, Br, or I, preferably Cl or Br. The co-catalyst used in this embodiment of the invention is benzyltriethylammonium chloride.

[0035] This invention provides a method for preparing the epoxy resin solidified body described above, comprising the following steps:

[0036] (1) Mix the co-catalyst, the main catalyst and the acid anhydride curing agent to obtain a mixed solution;

[0037] (2) After mixing epoxy resin, curing accelerator and the mixed solution of step (1), degassing and curing are carried out in sequence to obtain epoxy resin solid plastic.

[0038] In this invention, in step (1), the co-catalyst and the acid anhydride curing agent are first mixed, and then the main catalyst is added.

[0039] In this invention, the co-catalyst and the anhydride curing agent are first mixed, and then the main catalyst is added. Epoxy resin and a curing accelerator are then added to the resulting mixed solution, which improves the mechanical properties of the epoxy resin solid and the catalytic efficiency of the catalyst. Mixing the co-catalyst and the anhydride curing agent to obtain mixed solution 1, and mixing the main catalyst and epoxy resin to obtain mixed solution 2, and finally mixing mixed solutions 1, mixed solutions 2, and the curing accelerator, differs from the order of addition in this application. This will lead to a decrease in the catalytic performance of the catalyst and a reduction in the performance of the product.

[0040] In this invention, in step (2), the degassing speed is 1200-1800 rpm, preferably 1200 rpm, 1400 rpm, 1600 rpm, or 1800 rpm, and more preferably 1600 rpm or 1800 rpm; the degassing time is 2-6 min, preferably 3-5 min, and more preferably 4 min.

[0041] In this invention, step (2) includes curing, curing, and curing.

[0042] In this invention, the first curing temperature is 80-100℃, preferably 85-95℃, more preferably 90℃, and the first curing time is 0.5-1.5h, preferably 1h; the second curing temperature is 130-150℃, preferably 135-145℃, more preferably 130℃, and the second curing time is 0.5-1.5h, preferably 1h; the third curing temperature is 190-210℃, preferably 195-205℃, more preferably 200℃, and the third curing time is 0.5-1.5h, preferably 1h.

[0043] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0044] Example 1

[0045] Place 18.05g of methyltetrahydrophthalic anhydride in a beaker, add 0.37g of benzyltriethylammonium chloride, heat the beaker to 100°C, and stir at 500 rpm for 10 minutes at 100°C until the benzyltriethylammonium chloride is completely dissolved in the methyltetrahydrophthalic anhydride. After cooling to room temperature, add 1.27g of zinc methacrylate, and heat the beaker to 100°C again. At this temperature, stir at 600 rpm for 10 minutes until the zinc methacrylate is completely dissolved. After cooling to room temperature, a mixed solution is obtained.

[0046] 20.00g of bisphenol A type epoxy resin and 0.5g of 2,4,6-tris(dimethylaminomethyl)phenol curing accelerator were added to the above mixed solution. After stirring evenly, the solution was placed in a vacuum degassing machine at 1800rpm for 4min to degas. The degassed resin liquid was poured into a mold and then placed in an oven for curing. The process parameters for the curing process were as follows: the first curing temperature was 90℃ and the time was 1h; the second curing temperature was 140℃ and the time was 1h; and the third curing temperature was 200℃ and the time was 1h, to obtain an epoxy resin solid.

[0047] Example 2

[0048] Place 18.05g of phthalic anhydride in a beaker, add 0.3g of tetraethylammonium chloride, heat the beaker to 100°C, and stir at 500rpm for 10 minutes at 100°C until the tetraethylammonium chloride is completely dissolved in the phthalic anhydride. After cooling to room temperature, add 1.86g of zinc acetylacetonate, and heat the beaker to 100°C again. At this temperature, stir at 600rpm for 10 minutes until the zinc acetylacetonate is completely dissolved. After cooling to room temperature, a mixed solution is obtained.

[0049] 25.00g of diglycidyl phthalate and 0.5g of benzyl dimethylamine curing accelerator were added to the above mixed solution. After stirring evenly, the solution was placed in a vacuum degassing machine at 1600rpm for 5min to degas. The degassed resin liquid was poured into a mold and then placed in an oven for curing. The process parameters for the curing process were as follows: the first curing temperature was 80℃ and the time was 1.5h; the second curing temperature was 130℃ and the time was 1.5h; and the third curing temperature was 190℃ and the time was 1.5h, to obtain an epoxy resin solid.

[0050] Example 3

[0051] Place 15g of hexachloromethyltetrahydrophthalic anhydride in a beaker, add 0.5g of benzyltriethylammonium bromide, heat the beaker to 100℃, and stir at 500rpm for 10min at 100℃ until the benzyltriethylammonium bromide is completely dissolved in the hexachloromethyltetrahydrophthalic anhydride. After cooling to room temperature, add 1.29g of zinc acetate, and heat the beaker to 100℃ again. At this temperature, stir at 600rpm for 10min until the zinc acetate is completely dissolved. After cooling to room temperature, a mixed solution is obtained.

[0052] 15.00g of cyanuric acid epoxy resin and 0.3g of chromium octanoate curing accelerator were added to the above mixed solution. After stirring evenly, the solution was placed in a vacuum degassing machine at 1700rpm for 3 minutes to degas. The degassed resin liquid was poured into a mold and then placed in an oven for curing. The process parameters for the curing process were as follows: the first curing temperature was 100℃ and the time was 0.5h; the second curing temperature was 150℃ and the time was 0.5h; and the third curing temperature was 210℃ and the time was 0.5h, to obtain an epoxy resin solid.

[0053] Comparative Example 1

[0054] Mix 1.29g of zinc acetate and 20.00g of bisphenol A epoxy resin, heat to 140℃, and stir at 500rpm for 10min at this temperature until the zinc acetate is completely dissolved. Cool to room temperature to obtain mixed solution 1.

[0055] Add 18.05g of methyltetrahydrophthalic anhydride and 0.5g of 2,4,6-tris(dimethylaminomethyl)phenol curing accelerator to mixed solution 1, stir evenly, and then place it in a vacuum degassing machine at 1800rpm for 4min to degas. Pour the degassed resin liquid into a mold, and then place it in an oven for curing. The process parameters for the curing process are as follows: the first curing temperature is 90℃ and the time is 1h; the second curing temperature is 140℃ and the time is 1h; the third curing temperature is 200℃ and the time is 1h, to obtain an epoxy resin-based material.

[0056] Comparative Example 2

[0057] Mix 1.86g of zinc acetylacetone and 20.00g of bisphenol A epoxy resin, heat to 140℃, and stir at 500rpm for 10min at this temperature until the zinc acetylacetone is completely dissolved. Cool to room temperature to obtain mixed solution 1.

[0058] Add 18.05g of methyltetrahydrophthalic anhydride and 0.5g of 2,4,6-tris(dimethylaminomethyl)phenol curing accelerator to mixed solution 1, stir evenly, and then place it in a vacuum degassing machine at 1800rpm for 4min to degas. Pour the degassed resin liquid into a mold, and then place it in an oven for curing. The process parameters for the curing process are as follows: the first curing temperature is 90℃ and the time is 1h; the second curing temperature is 140℃ and the time is 1h; the third curing temperature is 200℃ and the time is 1h, to obtain an epoxy resin-based material.

[0059] Comparative Example 3

[0060] 18.05g of methyltetrahydrophthalic anhydride was placed in a beaker, and 0.37g of benzyltriethylammonium chloride was added. The beaker was heated to 100℃ and stirred at 500rpm for 10min until the benzyltriethylammonium chloride was completely dissolved in the methyltetrahydrophthalic anhydride. After cooling to room temperature, 20.00g of bisphenol A epoxy resin and 0.5g of 2,4,6-tris(dimethylaminomethyl)phenol curing accelerator were added. After stirring evenly, the mixture was placed in a vacuum degassing machine and degassed at 1800rpm for 4min. The degassed resin liquid was poured into a mold and then placed in an oven for curing. The curing process parameters were as follows: the first curing temperature was 90℃ and the time was 1h; the second curing temperature was 140℃ and the time was 1h; and the third curing temperature was 200℃ and the time was 1h, resulting in an epoxy resin-based material.

[0061] Comparative Example 4

[0062] 18.05g of methyltetrahydrophthalic anhydride was placed in a beaker, and 1.27g of zinc methacrylate was added. The beaker was heated to 100℃ and stirred at 600rpm for 10min until the zinc methacrylate was completely dissolved in the methyltetrahydrophthalic anhydride. After cooling to room temperature, 20.00g of bisphenol A epoxy resin and 0.5g of 2,4,6-tris(dimethylaminomethyl)phenol curing accelerator were added. After stirring evenly, the mixture was placed in a vacuum degassing machine and degassed at 1800rpm for 4min. The degassed resin liquid was poured into a mold and then placed in an oven for curing. The curing process parameters were as follows: the first curing temperature was 90℃ and the time was 1h; the second curing temperature was 140℃ and the time was 1h; and the third curing temperature was 200℃ and the time was 1h, resulting in an epoxy resin-based material.

[0063] Comparative Example 5

[0064] Place 18.05g of methyltetrahydrophthalic anhydride in a beaker, add 0.12g of benzyltriethylammonium chloride, heat the beaker to 100℃, and stir at 500rpm for 10min at 100℃ until the benzyltriethylammonium chloride is completely dissolved in the methyltetrahydrophthalic anhydride. After cooling to room temperature, add 1.27g of zinc methacrylate, heat the beaker to 100℃ again, and stir at 600rpm for 10min at this temperature until the zinc methacrylate is completely dissolved. After cooling to room temperature, a mixed solution is obtained.

[0065] 20.00g of bisphenol A type epoxy resin and 0.5g of 2,4,6-tris(dimethylaminomethyl)phenol curing accelerator were added to the above mixed solution. After stirring evenly, the solution was placed in a vacuum degassing machine at 1800rpm for 4min to degas. The degassed resin liquid was poured into a mold and then placed in an oven for curing. The process parameters for the curing process were as follows: the first curing temperature was 90℃ and the time was 1h; the second curing temperature was 140℃ and the time was 1h; and the third curing temperature was 200℃ and the time was 1h, to obtain an epoxy resin solid.

[0066] Comparative Example 6

[0067] Place 18.05g of methyltetrahydrophthalic anhydride in a beaker, add 0.7g of benzyltriethylammonium chloride, heat the beaker to 100°C, and stir at 500 rpm for 10 minutes at 100°C until the benzyltriethylammonium chloride is completely dissolved in the methyltetrahydrophthalic anhydride. After cooling to room temperature, add 1.27g of zinc methacrylate, and heat the beaker to 100°C again. At this temperature, stir at 600 rpm for 10 minutes until the zinc methacrylate is completely dissolved. After cooling to room temperature, a mixed solution is obtained.

[0068] 20.00g of bisphenol A type epoxy resin and 0.5g of 2,4,6-tris(dimethylaminomethyl)phenol curing accelerator were added to the above mixed solution. After stirring evenly, the solution was placed in a vacuum degassing machine at 1800rpm for 4min to degas. The degassed resin liquid was poured into a mold and then placed in an oven for curing. The process parameters for the curing process were as follows: the first curing temperature was 90℃ and the time was 1h; the second curing temperature was 140℃ and the time was 1h; and the third curing temperature was 200℃ and the time was 1h, to obtain an epoxy resin solid.

[0069] The raw material formulations for Examples 1-3 and Comparative Examples 1-6 are shown in Tables 1 and 2, respectively:

[0070] Table 1 Raw material formulations for Examples 1-3

[0071]

[0072] Note: In Table 1, the epoxy resins in Examples 1-3 are bisphenol A type epoxy resin, diglycidyl phthalate epoxy resin, and cyanuric acid epoxy resin, respectively; the acid anhydride curing agents are methyltetrahydrophthalic anhydride, phthalic anhydride, and hexachloromethyltetrahydrophthalic anhydride, respectively; the curing accelerators are 2,4,6-tris(dimethylaminomethyl)phenol, benzyl dimethylamine, and chromium octanoate, respectively; the main catalysts are zinc methacrylate, zinc acetylacetone, and zinc acetate, respectively; and the co-catalysts are benzyl triethylammonium chloride, tetraethylammonium chloride, and benzyl triethylammonium bromide, respectively.

[0073] Table 2. Raw material formulations for Comparative Examples 1–6

[0074]

[0075] Note: In Table 2, 550E is bisphenol A type epoxy resin, MTHPA is methyltetrahydrophthalic anhydride, TEBAC is benzyltriethylammonium chloride, C is 2,4,6-tris(dimethylaminomethyl)phenol, ZADM is zinc methacrylate, Zn(oAc)2 is zinc acetate, and Zn(acac)2 is zinc acetylacetone.

[0076] The performance of the epoxy resin solids of Examples 1-3 and the epoxy resin-based materials of Comparative Examples 1-6 was tested:

[0077] (1) Stress relaxation experiment:

[0078] The stress relaxation effect of the cured epoxy resin casting was tested using a TA Q800 Dynamic Thermomechanical Analyzer (DMA) from the United States. The sample size was 15mm×5mm×1mm. A tensile film fixture was used for the test. The pre-tension was 0.001N, the constant strain was 1%, the equilibrium time was 5min, and the test temperature was 250℃.

[0079] (2) Thermomechanical property determination:

[0080] The thermomechanical properties of the cured casting specimens were tested using a Q800 Dynamic Thermomechanical Analyzer (DMA) from TA Instruments, Inc. Storage modulus and loss tangent were measured in tensile mode at a frequency of 20 Hz, with the temperature increased from room temperature to 200 °C at a rate of 3 °C / min. To ensure consistency, the specimen dimensions were fixed at 15 mm × 5 mm × 1 mm.

[0081] (3) Repeated molding experiment:

[0082] The epoxy resin solid obtained in Example 1 was cut into small pieces and placed in a ball mill. The pieces were ball-milled at 1200 rpm for 6 minutes until powdered. The powder was then placed in a mold and hot-pressed at 240°C for 2 hours at 7 MPa. The repeated molding experiment process is described in [link to relevant documentation]. Figure 3 .

[0083] (4) Degradation experiment:

[0084] The epoxy resin solidified body obtained in Example 1 was cut into strips with dimensions of 20mm×10mm×1mm, placed in a transparent glass bottle containing 25g of ethylene glycol, and kept in an oven at 190℃ for 12 hours.

[0085] Generally, thermosetting polymers, due to their internal three-dimensional covalent cross-linked network structure, cannot relax their internal stress, thus preventing reprocessing and repeated molding. In contrast, solid plastic materials can rearrange their molecular topology through dynamic covalent bond exchange reactions at certain temperatures, reducing their modulus to below 1 / e of the initial modulus, thus granting them the ability to be repeatedly molded. Stress relaxation experiments are also an important way to distinguish between thermosetting and solid plastic materials. Figure 1 It can be seen that the epoxy resin-based materials prepared by using zinc methacrylate (Comparative Example 4) and benzyltriethylammonium chloride (Comparative Example 3) as catalysts alone cannot relax stress to 1 / e of the initial modulus. However, when the two are combined in a certain ratio for synergistic use, the material can undergo stress relaxation, that is, the modulus can decrease to 1 / e of the initial modulus (Example 1). Compared with Comparative Example 3, the relaxation modulus of Comparative Example 4 decreases more. Therefore, zinc methacrylate is designated as the main catalyst and benzyltriethylammonium chloride as the co-catalyst. On the other hand, from Figure 1It can also be seen that the relaxation time of Example 1 at 250°C is only 18 min, which is shorter than that of Comparative Examples 1 and 2. This indicates that the combined catalyst composed of zinc methacrylate and benzyltriethylammonium chloride has higher catalytic efficiency than the single-component catalysts zinc acetate and zinc acetylacetonate of equal mass. Examples 2 and 3 and Comparative Examples 2 and 3 show that adding a co-catalyst to a single-component catalyst can achieve synergistic catalysis and improve catalytic efficiency. Furthermore, from... Figure 1 Based on the stress relaxation conditions of Examples 1, 5, and 6 at 250°C, the ratio of the main catalyst to the co-catalyst in Comparative Example 5 is less than 1:0.1, so the relaxation modulus cannot be reduced to below 1 / e of the initial modulus. In Comparative Example 6, the ratio of the main catalyst to the co-catalyst is greater than 1:0.5, and although the modulus can relax to below 1 / e of the initial modulus, its relaxation time of 37 min is twice that of Example 1 (relaxation time of 18 min). Therefore, this combined catalyst needs to be used in a certain proportion to have catalytic effect and have the best catalytic efficiency within a certain range.

[0086] Figure 2 The graph shows the thermomechanical property test results of Example 1. It can be seen that the Tg of the epoxy resin solidified body after adding the combined transesterification catalyst is... g The temperature was 146℃, and the T was repeatedly molded. g The temperature is 138℃, T g The decrease was only about 5%, indicating that the epoxy resin solidified body after repeated molding still has good heat resistance. From Figure 3 As can be seen from the data, the epoxy resin solid in Example 1 is an amber-colored transparent solid. The resin sample after repeated hot pressing showed no difference from the sample before repeated molding and remained translucent, indicating that the epoxy resin solid with the addition of the combined transesterification catalyst has excellent reproducibility. Figure 4 As can be seen from the example, the epoxy resin solidified body of Example 1 can be completely degraded into oligomers under the action of the small molecule solvent ethylene glycol, indicating that the epoxy resin solidified body with the addition of the combined transesterification catalyst has recyclable properties.

[0087] As can be seen from the above embodiments, the present invention provides an epoxy resin solidified body and its preparation method. The epoxy resin solidified body of the present invention is made of epoxy resin, an anhydride curing agent, a curing accelerator, and a combined transesterification catalyst, wherein the mass ratio of epoxy resin, anhydride curing agent, curing accelerator, and combined transesterification catalyst is 30-50:30-50:0.1-2:1-10; the combined transesterification catalyst is composed of a main catalyst and a co-catalyst, wherein the mass ratio of the main catalyst and the co-catalyst is 1:0.1-0.5. By controlling the mass ratio of the main catalyst and the co-catalyst, the present invention significantly improves the catalytic efficiency of the combined transesterification catalyst, especially in the presence of a curing accelerator, and can effectively catalyze dynamic transesterification reactions. The epoxy resin solidified body obtained by the present invention not only has the excellent properties of traditional thermosetting epoxy resins but also has the advantages of being recyclable, re-molded, and biodegradable.

[0088] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An epoxy resin solidified body, characterized in that, The epoxy resin solidified body is made of epoxy resin, acid anhydride curing agent, curing accelerator and combined transesterification catalyst, wherein the mass ratio of epoxy resin, acid anhydride curing agent, curing accelerator and combined transesterification catalyst is 30-50:30-50:0.1-2:1-10; the combined transesterification catalyst is composed of a main catalyst and a co-catalyst, wherein the mass ratio of the main catalyst and the co-catalyst is 1:0.1-0.

5. The main catalyst comprises one or more of zinc methacrylate, zinc acetylacetone, zinc acetate, triphenylphosphine, and titanate; the co-catalyst comprises benzyl quaternary ammonium salt or alkyl quaternary ammonium salt.

2. The epoxy resin solidified body according to claim 1, characterized in that, The epoxy resin includes glycidyl ether epoxy resin, glycidyl ester epoxy resin, glycidyl amine epoxy resin, alicyclic epoxy resin, or epoxidized olefin epoxy resin.

3. The epoxy resin solidified body according to claim 2, characterized in that, The anhydride curing agent comprises aromatic anhydride, aliphatic anhydride, alicyclic anhydride or halogen-containing anhydride; the curing accelerator comprises one or more of 2,4,6-tris(dimethylaminomethyl)phenol, chromium octanoate, benzyldimethylamine, imidazole and metal salts of acetylacetone.

4. The epoxy resin solidified body according to claim 1, characterized in that, The chemical formula of the benzyl quaternary ammonium salt is C n H 2n-4 R1N, where n is an integer greater than or equal to 10, and R1 is F, Cl, Br, or I; the chemical formula of the alkyl quaternary ammonium salt is C m H 2m+ 4R2N, where m is an integer greater than or equal to 4, and R2 is F, Cl, Br, or I.

5. The method for preparing the epoxy resin solidified body according to any one of claims 1 to 4, characterized in that, Includes the following steps: (1) Mix the co-catalyst, the main catalyst and the acid anhydride curing agent to obtain a mixed solution; (2) After mixing epoxy resin, curing accelerator and the mixed solution of step (1), degassing and curing are carried out in sequence to obtain epoxy resin solid plastic.

6. The method for preparing the epoxy resin solidified body according to claim 5, characterized in that, In step (1), the co-catalyst and the acid anhydride curing agent are first mixed, and then the main catalyst is added.

7. The method for preparing the epoxy resin solid according to claim 5 or 6, characterized in that, In step (2), the degassing speed is 1200-1800 rpm and the degassing time is 2-6 min.

8. The method for preparing the epoxy resin solid according to claim 7, characterized in that, In step (2), curing includes first curing, second curing and third curing.

9. The method for preparing the epoxy resin solid according to claim 8, characterized in that, The first curing temperature is 80-100℃, and the first curing time is 0.5-1.5h; the second curing temperature is 130-150℃, and the second curing time is 0.5-1.5h; the third curing temperature is 190-210℃, and the third curing time is 0.5-1.5h.

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