A water-degradable epoxy resin and its preparation method

Abstract

The present invention discloses a water-degradable epoxy resin and a preparation method thereof. Using tetraethyl orthosilicate and methyldiethanolamine as raw materials, hyperbranched polysiloxane is obtained through a one-pot polycondensation reaction; the hyperbranched polysiloxane is mixed with an epoxy / anhydride resin system and cured to obtain an epoxy resin that can be degraded and recycled in water. Compared with the prior art, the water-degradable epoxy resin provided by the present invention does not require the presence of traditional metal catalysts, overcoming the defect of large pollution caused by traditional metal catalysts; at the same time, this epoxy resin has good toughness. In view of the deficiencies of the prior art, the present invention provides a water-degradable epoxy resin and a preparation method thereof, which has the generality of commercially available epoxy resins, is cured by an anhydride, and can be effectively degraded and recycled in pure water. In particular, the water-degradable epoxy resin of the present invention has significantly higher heat resistance and excellent mechanical properties than the prior art, and can be used in fields such as electronic circuits and aerospace.

Description

Technical Field

[0001] The present invention relates to a water-degradable epoxy resin and a preparation method thereof, belonging to the technical field of functional polymer materials. Background Art

[0002] Epoxy resin is one of the most widely used thermosetting resins at present, showing great application value in cutting-edge industrial fields such as electronic information, aerospace, electrical insulation, and rail transit. Due to the covalent cross-linked network, thermosetting resins are insoluble and infusible and cannot be reprocessed or reshaped by heating or using solvents. Waste thermosetting resins and related products are usually treated by incineration, landfill, etc., resulting in the ineffective recycling of resins, causing a large amount of resource waste and environmental pollution. To solve the problems of environmental pollution and resource shortage and green sustainable development, the recycling of thermosetting resins after their effective service life has become an urgent problem to be solved. Existing technologies design and synthesize new epoxy resins containing reversible dynamic covalent bonds to achieve the purpose of resin degradation through the degradation of reversible dynamic covalent bonds under specific conditions, but generally require the use of acids, bases, or organic solvents. In addition, for epoxy resins with dynamic ester bonds, metal catalysts are often required. These metal catalysts are mainly zinc acetylacetonate, which has the disadvantages of high pollution and toxicity.

[0003] It is worth pointing out that in order to achieve the degradation and recycling of thermosetting resins, existing technologies need to design and synthesize new resins, which means that existing resins and their production lines for manufacturing various materials need to be abandoned. The engineering realization of a new resin requires a large amount of time, manpower, and material resources. In particular, in order to meet the requirements of degradability, existing technologies often sacrifice other properties of thermosetting resins, such as heat resistance and mechanical properties will be reduced, which limits the application of thermosetting resins. Summary of the Invention

[0004] In view of the deficiencies of the prior art, the present invention provides a water-degradable epoxy resin and a preparation method thereof, which has the versatility of commercially available epoxy resins, is cured by acid anhydride, and can be effectively degraded and recycled in pure water. In particular, the water-degradable epoxy resin of the present invention has significantly higher heat resistance and excellent mechanical properties than the prior art.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] A preparation method of a water-degradable epoxy resin, comprising the following steps: reacting tetraethyl orthosilicate with N-methyldiethanolamine to prepare hyperbranched polysiloxane; mixing epoxy resin and the hyperbranched polysiloxane, then adding acid anhydride and curing to obtain a water-degradable epoxy resin.

[0007] Further, tetraethyl orthosilicate and N-methyldiethanolamine are reacted at a molar ratio of 1:(3-5) at 100-180 °C for 6-9 h to obtain hyperbranched polysiloxane.

[0008] In the present invention, the epoxy resin includes one or more of glycidyl ether type epoxy resins (such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenolic type epoxy resin), glycidyl ester type epoxy resin, glycidyl amine type epoxy resin, alicyclic epoxy resin, and linear aliphatic epoxide; the acid anhydride includes one or more of hexahydrophthalic anhydride, tetrahydrophthalic anhydride, phthalic anhydride, glutaric anhydride, adipic anhydride, dodecenyl succinic anhydride, methyl nadic anhydride, and biomass acid anhydride.

[0009] In the present invention, the epoxy resin and the hyperbranched polysiloxane are mixed, then the acid anhydride is added and mixed, and then cured to obtain a water-degradable epoxy resin. Preferably, the epoxy resin and the hyperbranched polysiloxane are mixed at room temperature to 100 °C for 5-20 minutes, then the acid anhydride is added, and they are mixed at room temperature to 100 °C, and then cured to obtain a water-degradable epoxy resin. As common knowledge, after adding the acid anhydride, it is sufficient to mix evenly, generally for 5-15 minutes, and then defoamed and cured.

[0010] In the present invention, the molar ratio of the epoxy resin to the acid anhydride is 1:(2.5-5), preferably 1:(3-4); the mass ratio of the epoxy resin to the hyperbranched polysiloxane is 100:(4-20), preferably 100:(8-12).

[0011] In the present invention, the curing temperature is 120-190 °C and the time is 5-10 h. Preferably, the curing is in a stepwise temperature increase manner, with the holding time at each step temperature being not less than 1 h and the temperature difference between adjacent steps not exceeding 30 °C.

[0012] The present invention discloses a water-degradable epoxy resin prepared by the preparation method of the above-mentioned water-degradable epoxy resin. As common knowledge, the water referred to in the present invention refers to water without adding additional reagents (including acids, bases, etc.), including tap water, deionized water, double-distilled water, distilled water, pure water, etc., which can be called pure water.

[0013] The present invention discloses a degradation method of the above-mentioned water-degradable epoxy resin, including the following steps: placing the water-degradable epoxy resin in water to achieve the degradation of the water-degradable epoxy resin.

[0014] The present invention discloses a recovery method of the above-mentioned water-degradable epoxy resin, including the following steps: placing the water-degradable epoxy resin in water, and removing the water when the water-degradable epoxy resin is completely degraded to achieve the recovery of the water-degradable epoxy resin.

[0015] Specifically, the above-mentioned water-degradable epoxy resin is mixed with pure water to achieve its degradation; preferably, the degradation is carried out at 170-200 °C. In the present invention, the water-degradable epoxy resin block is placed in pure water and can be completely degraded within 5 hours, and the degradation rate is significantly faster than that of the prior art. The water in the degraded aqueous solution is evaporated, and the residue is the recovered epoxy resin.

[0016] The present invention discloses the application of the above-mentioned water-degradable epoxy resin in the preparation or as an epoxy resin material, especially in the preparation of functional epoxy resin materials, particularly in the preparation of water-degradable epoxy resin materials, such as in the preparation of heat-resistant water-degradable epoxy resin materials.

[0017] The present invention aims to develop an epoxy resin that can be degraded and recovered in pure water and its preparation method; the epoxy resin that can be degraded and recovered in pure water can be obtained by using commercially available epoxy resin and curing agent; effectively solving the problems that the prior art needs to develop new epoxy resin structures, mostly uses acids and bases or even more harsh degradation liquids, and the heat resistance and mechanical properties of epoxy resin are poor.

[0018] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0019] 1. The present invention uses existing epoxy resins such as N,N,N’,N’-tetraglycidyl-4,4’-diaminodiphenylmethane and existing anhydrides such as methyl nadic anhydride and hyperbranched polysiloxane as raw materials. The prepared epoxy resin that can be degraded and recovered in pure water has outstanding heat resistance, and the glass transition temperature (T g g) is 240 °C, and it also has a high flexural modulus (4.23 GPa) and strength (82.71 MPa), and at the same time has a high tensile strength (61.88 MPa), thus providing a reliable basis for its application in cutting-edge fields.

[0020] 2. The epoxy resin prepared by the present invention has the advantage of being degradable in water, enabling the decomposition of its crosslinked network, and the prepared water-degradable epoxy resin is completely degraded; these application methods overcome the defect that traditional crosslinked polymers cannot be degraded and recovered in water after molding. Description of the Drawings

[0021] Figure 1 is a schematic diagram of the synthesis reaction for preparing hyperbranched polysiloxane in Example 1 of the present invention.

[0022] Figure 2 is the nuclear magnetic resonance hydrogen spectrum ( 1 1H-NMR) of hyperbranched polysiloxane in Example 1 of the present invention.

[0023] Figure 3 is the nuclear magnetic resonance carbon spectrum ( 13 13C-NMR) of hyperbranched polysiloxane in Example 1 of the present invention.

[0024] Figure 4 shows the silicon nuclear magnetic resonance spectrum ( 29 29 Si-NMR) of the hyperbranched polysiloxane in Example 1 of the present invention.

[0025] Figure 5 shows the thermogravimetric (TGA) curve of the epoxy resin prepared in Example 1 of the present invention, at 10 °C / min under nitrogen.

[0026] Figure 6 shows the dynamic thermomechanical analysis (DMA) curve of the epoxy resin prepared in Example 1 of the present invention, at 3 °C / min.

[0027] Figure 7 shows the tensile stress-strain curve of the epoxy resin prepared in Example 1 of the present invention.

[0028] Figure 8 shows the degradation curve of the epoxy resin prepared in Example 1 of the present invention.

[0029] Figure 9 shows a photograph of the epoxy resin prepared in Example 1 of the present invention before degradation.

[0030] Figure 10 shows a photograph of the epoxy resin prepared in Example 1 of the present invention after degradation. Detailed implementation manners

[0031] In the present invention, tetraethyl orthosilicate and methyldiethanolamine are reacted to obtain hyperbranched polysiloxane, and the hyperbranched polysiloxane is cured with epoxy resin and anhydride to obtain an epoxy resin that can be degraded and recycled in pure water; as an example, the epoxy resin that can be degraded and recycled in pure water is cured from N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane and methyl nadic anhydride with hyperbranched polysiloxane. In the present invention, when curing to prepare an epoxy resin that can be degraded and recycled in pure water, no accelerator is added. As common knowledge, the water described in the present invention refers to water without adding extra reagents (including acids, alkalis, etc.), including tap water, deionized water, double-distilled water, distilled water, pure water, etc.

[0032] The technical solution of the present invention will be further described below in conjunction with the drawings and examples; all raw materials are commercially available, and the specific preparation operations and testing methods involved are conventional methods in the art. A universal testing machine (MTS CMT-4104) is used to test the mechanical properties, and the test standard for the tensile test refers to the material test standard ASTM-D882, and the test standard for the bending test refers to the material test standard GBT2570-1995. A nuclear magnetic resonance instrument is used to test 1 H-NMR and 1313C-NMR spectra were recorded in CDCl3 or DMSO-d6 as the solvent. The thermal stability of the resin was investigated using a thermogravimetric analyzer (TGA) under a nitrogen atmosphere. The sample was heated from room temperature to 800 °C at a heating rate of 10 °C / min. The dynamic thermomechanical properties of the material were tested using a dynamic thermomechanical analyzer (DMA) at a frequency of 1 Hz, heating from 25 °C to 350 °C at a heating rate of 3 °C / min, and the specimen size was 35 mm × 4.9 mm × 1 mm.

[0033] As an example, the preparation process of the water-degradable epoxy resin disclosed in the present invention is as follows:

[0034] (1) After heating and reacting tetraethyl orthosilicate with N-methyldiethanolamine, a hyperbranched polysiloxane was obtained; the reaction schematic diagram is shown in Figure 1 ;

[0035] (2) The hyperbranched polysiloxane and N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane were cured with methyl nadic anhydride to obtain a recyclable epoxy resin.

[0036] Preferably, in step (1), the molar ratio of tetraethyl orthosilicate to N-methyldiethanolamine is 1:4; the heating reaction temperature is 110-180 °C, and the time is 5-8 h. Preferably, the heating reaction is a stepwise temperature increase; in step (2), the curing temperature is 120-190 °C, and the time is 5-16 h. Preferably, the curing is in a stepwise temperature increase manner, with a holding time of not less than 1 h at each step temperature, and the temperature difference between adjacent steps not exceeding 30 °C.

[0037] Specifically, the preparation method of the water-degradable epoxy resin of the present invention is as follows:

[0038] (1) By mole fraction, 100 parts of tetraethyl orthosilicate and 400 parts of N-methyldiethanolamine were mixed, and then stirred and reacted for 6-9 h. Starting from 110 °C, the temperature was increased stepwise by 10 °C per hour (reacting at 110 °C for 1 hour, then at 120 °C for 1 hour, then at 130 °C for 1 hour, and so on in a stepwise temperature increase), and then naturally cooled to room temperature, and then dialyzed to obtain a hyperbranched polysiloxane;

[0039] (2) The hyperbranched polysiloxane obtained in step (1) and N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane were mixed, then methyl nadic anhydride was added, degassed, and then cured to obtain a water-degradable and recyclable epoxy resin. Example 1

[0040] (1) Preparation of hyperbranched polysiloxane

[0041] Mix 23.152 g of N-methyldiethanolamine (CAS#: 105-59-9) and 10.118 g of tetraethyl orthosilicate (CAS#: 78-10-4), then stir and react for 6 h, with the temperature rising stepwise by 10 °C per hour starting from 110 °C, and then naturally cooling to room temperature; then use a dialysis bag with a molecular weight cut-off of 1000 and ethanol as the dialysis solution to dialyze the crude product for 24 hours, changing the dialysis solution at 4 hours, 8 hours, and 12 hours respectively to remove unreacted raw materials and small molecule polymers, and then rotary evaporate (50 °C, 0.1 MPa) to remove ethanol to obtain hyperbranched polysiloxane with a yield of 96.95%; its nuclear magnetic resonance hydrogen spectrum ( 1 1H-NMR), nuclear magnetic resonance carbon spectrum ( 13 13C-NMR), and nuclear magnetic resonance silicon spectrum ( 29 29Si-NMR) are shown in Appendices Figure 2 , Figure 3 , Figure 4 respectively.

[0042] (2) Preparation of water-degradable epoxy resin

[0043] Mix 15.441 g of N,N,N’,N’-tetraglycidyl-4,4’-diaminodiphenylmethane monomer and 1.251 g of hyperbranched polysiloxane at 80 °C for 10 minutes, then add 24.705 g of methyl nadic anhydride and mix well at 80 °C (for 10 minutes), then pour it into a mold conventionally, and then perform degassing (80 °C, 10 min, 0.1 MPa), and then cure it according to the process of 120 °C / 2 h + 140 °C / 2 h + 160 °C / 2 h + 180 °C / 2 h + 190 °C / 1 h in sequence; after curing, let it cool naturally with the oven to obtain water-degradable epoxy resin, which is apparently homogeneous, without turbidity and bubbles; its thermogravimetric curve, dynamic thermomechanical analysis (DMA) curve, and tensile stress-strain curve are shown in Figure 5 , Figure 6 , Figure 7 respectively.

[0044] The glass transition temperature (T g DMA) of the above recyclable epoxy resin is 240 °C, and T d5% is 323 °C. Further, the flexural modulus, flexural strength, and tensile strength of the above water-degradable epoxy resin at room temperature are 4.229 GPa, 82.71 MPa, and 61.88 MPa respectively, showing outstanding mechanical properties.

[0045] Place a small piece of resin (weighing about 2 g, with dimensions of about 30 mm × 40 mm × 1 mm) in 50 mL of pure water and degrade it at different temperatures for different times (parallel experiments), and the test results are as shown in Figure 8As shown, the resin has a degradation rate of 93.33% in deionized water at a temperature of 200°C in 4 hours and can be completely degraded within 4.5 hours.

[0046] Calculation method of degradation rate: mass of the residual resin block or residue after drying / mass of the original resin block × 100%.

[0047] Figure 9 is a photo of the above epoxy resin of the present invention before degradation; Figure 10 is a photo of the epoxy resin after degradation (at 200°C for 4.5 hours).

[0048] In view of the deficiencies of the prior art, the present invention provides a water-degradable epoxy resin and its preparation method, which has the generality of commercially available epoxy resins, is cured by acid anhydride, and can be effectively degraded and recycled in pure water. In particular, the water-degradable epoxy resin of the present invention has significantly higher heat resistance and excellent mechanical properties compared with the prior art.

[0049] Comparative Example 1

[0050] Mix 15.441 g of N,N,N’,N’-tetraglycidyl-4,4’-diaminodiphenylmethane monomer, 1.251 g of hyperbranched polysiloxane (prepared in Example 1), and 24.705 g of methyl nadic anhydride at 80°C for 20 minutes, then pour them into a mold conventionally, and then perform degassing (80°C, 10 min, 0.1 MPa). Then, cure according to the process of 120°C / 2 h + 140°C / 2 h + 160°C / 2 h + 180°C / 2 h + 190°C / 1 h in sequence; after the curing is completed, let it cool naturally with the oven. The obtained epoxy resin has some turbid places, and there are small bubbles in the turbid places, indicating that the one-step mixing method makes the product unqualified.

[0051] Comparative Example 2

[0052] Mix 15.441 g of N,N,N’,N’-tetraglycidyl-4,4’-diaminodiphenylmethane monomer and 24.705 g of methyl nadic anhydride at 80°C for 10 minutes, then add 1.251 g of hyperbranched polysiloxane and mix at 80°C for 10 minutes. Then, pour them into a mold conventionally, and then perform degassing (80°C, 10 min, 0.1 MPa). Then, cure according to the process of 120°C / 2 h + 140°C / 2 h + 160°C / 2 h + 180°C / 2 h + 190°C / 1 h in sequence; after the curing is completed, let it cool naturally with the oven. The obtained epoxy resin is incompletely and unevenly cured with defects, has different transparencies, is turbid in many places, the turbid places are brittle and have small bubbles, and the product is unqualified.

[0053] Comparative Example 3

[0054] Referring to Example 1, the amounts of the three raw materials are as follows: 15.251 g of N,N,N',N'-tetracyclyl-4,4'-diaminodiphenylmethane monomer, 1.061 g of hyperbranched polysiloxane (prepared in Example 1), and 8.428 g of methyl nadic anhydride; the rest are the same; after the curing is completed, the epoxy resin is obtained by natural cooling in the oven, and the degradation rate of the resin in pure water at 190°C for 4 hours is only 7.51%.

[0055] Comparative Example 4

[0056] Referring to Example 1, the amounts of the three raw materials are as follows: 13.121 g of N,N,N',N'-tetraepoxypropyl-4,4'-diaminodiphenylmethane monomer, 1.049 g of hyperbranched polysiloxane (prepared in Example 1), and 13.151 g of methyl nadic anhydride; the rest are the same; after the curing is completed, the epoxy resin is obtained by natural cooling in the oven, and the degradation rate of the resin in pure water at 190°C for 4 hours is only 15.11%. Example 2

[0057] (1) Preparation of hyperbranched polysiloxane

[0058] 20.546 g of N-methyldiethanolamine and 8.98 g of ethyl orthosilicate were mixed, stirred and reacted at 100° C. for 10 h, the temperature was increased by 5° C. every 30 min until it reached 185° C., and the mixture was naturally cooled to room temperature. Unreacted raw materials and small molecular polymers were removed by ethanol dialysis, and then ethanol was removed by rotary evaporation (50° C., 0.1 MPa) to obtain hyperbranched polysiloxane.

[0059] (2) Preparation of recyclable epoxy resin

[0060] 5.40g of N,N,N',N'-tetraepoxypropyl-4,4'-diaminodiphenylmethane monomer and 0.436g of hyperbranched polysiloxane were mixed evenly, and then 8.641g of methyl nadic anhydride were added and mixed evenly at 80°C, and then put into a mold, and the mold was placed in a vacuum oven for degassing (80°C, 10min, 0.1MPa), and then the mold was placed in a blast drying oven and cured in sequence according to the process of 110°C / 2h + 130°C / 2h + 150°C / 2h + 170°C / 2h + 210°C / 1h; after the curing was completed, the epoxy resin was obtained by natural cooling in the oven. Example 3

[0061] (1) Preparation of hyperbranched polysiloxane

[0062] 9.44 g of tetraethyl orthosilicate and 21.60 g of methyldiethanolamine were mixed and stirred at 110 °C for 6 h with a stepwise temperature increase of 10 °C per hour, then naturally cooled to room temperature. The unreacted raw materials and small molecule polymers were removed by ethanol dialysis, and then ethanol was removed by rotary evaporation (50 °C, 0.1 MPa) to obtain hyperbranched polysiloxane.

[0063] (2)Preparation of recyclable epoxy resin

[0064] 7.20 g of N,N,N’,N’-tetraglycidyl-4,4’-diaminodiphenylmethane monomer and 0.368 g of hyperbranched polysiloxane were mixed evenly, then 11.448 g of methyl nadic anhydride was added and mixed evenly at 80 °C. It was put into a mold, and the mold was put into a vacuum oven for degassing (80 °C, 10 min, 0.1 MPa). Then the mold was put into a forced-air drying oven and cured according to the process of 120 °C / 2 h + 140 °C / 2 h + 160 °C / 2 h + 185 °C / 1 h in sequence; after the curing was completed, it was naturally cooled with the oven to obtain epoxy resin. Example 4

[0065] (1)Preparation of hyperbranched polysiloxane

[0066] 9.00 g of tetraethyl orthosilicate and 20.571 g of methyldiethanolamine were mixed and stirred at 120 °C for 6 h with a stepwise temperature increase of 10 °C per hour, then naturally cooled to room temperature. The unreacted raw materials and small molecule polymers were removed by ethanol dialysis, and then ethanol was removed by rotary evaporation (50 °C, 0.1 MPa) to obtain hyperbranched polysiloxane.

[0067] (2)Preparation of recyclable epoxy resin

[0068] 6.42 g of N,N,N’,N’-tetraglycidyl-4,4’-diaminodiphenylmethane monomer and 0.77 g of hyperbranched polysiloxane were mixed evenly, then 10.02 g of methyl nadic anhydride was added and mixed evenly at 80 °C. It was put into a mold, and the mold was put into a vacuum oven for degassing (80 °C, 10 min, 0.1 MPa). Then the mold was put into a forced-air drying oven and cured according to the process of 110 °C / 2 h + 130 °C / 2 h + 150 °C / 2 h + 170 °C / 2 h + 185 °C / 1 h in sequence; after the curing was completed, it was naturally cooled with the oven to obtain epoxy resin. Example 5

[0069] (1)Preparation of hyperbranched polysiloxane

[0070] 22.83 g of ethyl orthosilicate and 52.23 g of methyldiethanolamine were mixed, stirred and reacted at 110° C. for 7 h, the temperature was increased by 10° C. per hour, and the mixture was naturally cooled to room temperature. Unreacted raw materials and small molecular polymers were removed by ethanol dialysis, and then ethanol was removed by rotary evaporation (50° C., 0.1 MPa) to obtain hyperbranched polysiloxane.

[0071] (2) Preparation of recyclable epoxy resin

[0072] 17.32g of N,N,N',N'-tetraepoxypropyl-4,4'-diaminodiphenylmethane monomer and 3.491g of hyperbranched polysiloxane were mixed evenly, and 27.60g of methyl nadic anhydride was added and mixed evenly at 80°C, and put into a mold. The mold was placed in a vacuum oven for degassing (80°C, 30min, 0.1MPa), and then the mold was placed in a blast drying oven and cured in sequence according to the process of 110°C / 2 h + 130°C / 2 h + 150°C / 2 h + 170°C / 2 h + 185°C / 1 h; after the curing was completed, the epoxy resin was obtained by natural cooling in the oven.

[0073] The epoxy resin degradation methods previously disclosed by the inventors all utilize solvents to react with the resin to break the chemical bonds within the resin to form small molecules that cannot be degraded in pure water. The present invention uses tetraethyl orthosilicate and methyldiethanolamine as raw materials to synthesize a hyperbranched polysiloxane containing a large amount of tertiary amines and hydroxyls. The prepared recyclable epoxy resin has outstanding heat resistance and a glass transition temperature (T g ) is 240°C, it also has a high flexural modulus (4.229GPa) and strength (82.71.1MPa), and it also has a high tensile strength (61.88MPa). Compared with the prior art, the present invention realizes a water-degradable epoxy resin, and the resin has very excellent comprehensive properties, thus providing a reliable foundation for its application in cutting-edge fields (such as aerospace).

Claims

1. A method for preparing a water-degradable epoxy resin, characterized in that: The following steps are involved: According to the molar ratio of 1: (3-5), tetraethyl orthosilicate and N-methyldiethanolamine are reacted at 100-180°C for 6-9 hours to obtain hyperbranched polysiloxane; epoxy resin and the hyperbranched polysiloxane are mixed, and then acid anhydride is added and mixed, and then cured to obtain a water-degradable epoxy resin; the molar ratio of epoxy resin to acid anhydride is 1: (3-4); the mass ratio of epoxy resin to hyperbranched polysiloxane is 100: (8-12).

2. The method for preparing a water-degradable epoxy resin according to claim 1, characterized in that: The epoxy resin includes one or more of glycidyl ether epoxy resin, glycidyl ester epoxy resin, glycidyl amine epoxy resin, alicyclic epoxy resin, and linear aliphatic epoxy compound; the acid anhydride includes one or more of hexahydrophthalic anhydride, tetrahydrophthalic anhydride, phthalic anhydride, glutaric anhydride, adipic anhydride, dodecenyl succinic anhydride, methyl nadic anhydride, and biomass anhydride.

3. The method for preparing a water-degradable epoxy resin according to claim 1, characterized in that: The epoxy resin and the hyperbranched polysiloxane are mixed at room temperature to 100° C. for 5 to 20 minutes, and then anhydride is added, mixed at room temperature to 100° C., and then cured to obtain a water-degradable epoxy resin.

4. The water-degradable epoxy resin prepared according to the method for preparing a water-degradable epoxy resin according to claim 1.

5. The method for degrading a water-degradable epoxy resin according to claim 4, characterized in that: The water-degradable epoxy resin is placed in water to achieve degradation of the water-degradable epoxy resin.

6. The method for recovering the water-degradable epoxy resin according to claim 4, characterized in that: The water-degradable epoxy resin is placed in water, and the water is removed when the water-degradable epoxy resin is completely degraded, thereby realizing the recovery of the water-degradable epoxy resin.

7. Use of the water-degradable epoxy resin according to claim 4 in the preparation of or as epoxy resin material.

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