Degradable epoxy resin containing cyclic acetal structure as well as preparation method and application of degradable epoxy resin

Abstract

The invention belongs to the technical field of epoxy resin, and provides degradable epoxy resin containing a cyclic acetal structure and a preparation method and application thereof.The epoxy resin is based on alicyclic epoxy resin, the cyclic acetal structure is introduced into the alicyclic epoxy resin structure, the cyclic acetal structure has degradability under the acidic condition, and therefore the cyclic acetal structure can be degraded under the acidic condition; the rigidity of the annular structure is favorable for improving the mechanical property of the epoxy resin, and the finally obtained epoxy resin has the characteristics of good mechanical property, ultraviolet radiation resistance and suitability for the field of photocuring. According to the preparation method provided by the invention, 3-cyclohexene-1-formaldehyde and tetrahydric alcohol are taken as raw materials, and the epoxy resin is obtained through nucleophilic addition reaction and epoxidation reaction.

Description

Technical Field

[0001] The present invention relates to the technical field of epoxy resins, in particular to a degradable epoxy resin containing a cyclic acetal structure, a preparation method and an application thereof. Background Art

[0002] Epoxy resin is a high-molecular-weight polymer containing two or more epoxy groups in its molecular structure. These epoxy groups can cross-link with a variety of curing agents to form a thermoset product. Epoxy resins possess numerous excellent properties, including good adhesion, electrical insulation, chemical stability, heat resistance, and low shrinkage. Consequently, they are widely used in both everyday life and high-tech applications, including coatings, adhesives, electronics, aerospace, automotive, and construction. However, the irreversible cross-linking network of traditional epoxy resins, which endows them with these excellent properties, also presents significant limitations. Once cured, epoxy resins are no longer reprocessable, are difficult to repair after damage or aging, and are also difficult to recycle. Currently, the common disposal methods for unusable epoxy resins are incineration or landfilling, both of which have significant drawbacks. Incineration can release harmful gases that pollute the atmosphere, while landfilling occupies land resources for long periods of time, hindering sustainable land use. These disposal methods not only waste resources but also place a long-term burden on the ecological environment, inconsistent with the circular economy and sustainable development concepts advocated by today's society. Therefore, the development of recyclable and biodegradable high-performance epoxy resins is not only an important basic research topic, but also has economic value and environmental significance. Summary of the Invention

[0003] The purpose of the present invention is to overcome the defects of the prior art and provide a degradable epoxy resin containing a cyclic acetal structure and a preparation method and application thereof.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0005] The present invention provides a degradable epoxy resin containing a cyclic acetal structure. The structure of the degradable epoxy resin containing a cyclic acetal structure is shown below:

[0006]

[0007]

[0008] The present invention also provides a method for preparing the degradable epoxy resin containing a cyclic acetal structure, comprising the following steps:

[0009] (1) In a protective atmosphere, tetraol, 3-cyclohexene-1-carboxaldehyde, p-toluenesulfonic acid monohydrate and a solvent are mixed to undergo a nucleophilic addition reaction to obtain a bicyclic intermediate;

[0010] (2) Mixing the bicyclic intermediate solution, the epoxidation reagent solution and the alkaline solution to carry out epoxidation reaction, thereby obtaining the degradable epoxy resin containing the cyclic acetal structure.

[0011] Preferably, the tetrahydric alcohol in step (1) is pentaerythritol, erythritol or dipropylene glycol;

[0012] The solvent in step (1) is one or more of petroleum ether, N,N-dimethylformamide, n-hexane, dichloromethane, tetrahydrofuran, acetone and butanone.

[0013] Preferably, the molar ratio of the tetraol to 3-cyclohexene-1-carboxaldehyde in step (1) is 1:2-3.

[0014] Preferably, the mass of p-toluenesulfonic acid monohydrate in step (1) is 1 to 3% of the total mass of tetraol and 3-cyclohexene-1-carboxaldehyde.

[0015] Preferably, the nucleophilic addition reaction in step (1) lasts for 12 to 24 hours.

[0016] Preferably, the bicyclic intermediate solution in step (2) comprises a bicyclic intermediate, 18-crown-6-ether and a solvent;

[0017] The solvent is one or more of dichloromethane, chloroform, tetrahydrofuran, N,N-dimethylformamide, methyl pyrrolidone and acetone;

[0018] The molar volume ratio of the bicyclic intermediate, 18-crown-6-ether and solvent is 1 mol: 0.1-0.2 mol: 5-7 L.

[0019] Preferably, the epoxidation reagent solution in step (2) comprises an epoxidation reagent, ethylenediaminetetraacetic acid and a solvent;

[0020] The epoxidation reagent is one or more of potassium persulfate complex, peracetic acid, peroxybenzoic acid, m-chloroperoxybenzoic acid, p-nitroperoxybenzoic acid and m-nitroperoxybenzoic acid;

[0021] The solvent is one or more of dichloromethane, chloroform, tetrahydrofuran, N,N-dimethylformamide, methyl pyrrolidone, acetone and water;

[0022] The molar volume ratio of the epoxidation reagent, ethylenediaminetetraacetic acid and solvent is 250-260 mmol: 0.15-0.2 mmol: 250-300 mL.

[0023] Preferably, the molar ratio of the bicyclic intermediate to the epoxidation reagent in step (2) is 1:7.5-10;

[0024] The concentration of the alkaline solution in step (2) is 0.4 to 0.8 M;

[0025] The epoxidation reaction in step (2) is carried out at a temperature of 0 to 5° C. and for a time of 5 to 8 hours.

[0026] The present invention also provides application of the degradable epoxy resin containing a cyclic acetal structure in degradable materials.

[0027] The present invention provides a degradable epoxy resin containing a cyclic acetal structure. The epoxy resin provided by the present invention is based on an alicyclic epoxy resin, and a cyclic acetal structure is introduced into the alicyclic resin structure. The cyclic acetal structure is degradable under acidic conditions, and the rigidity of the ring structure is conducive to improving the mechanical properties of the epoxy resin. The resulting epoxy resin has good mechanical properties, is resistant to ultraviolet radiation, and is suitable for the field of photocuring.

[0028] The present invention also provides a method for preparing the alicyclic epoxy resin containing a cyclic acetal structure described in the above scheme. The preparation method provided by the present invention uses 3-cyclohexene-1-carboxaldehyde and tetraol as raw materials to obtain the epoxy resin through nucleophilic addition reaction and epoxidation reaction. DETAILED DESCRIPTION

[0029] The present invention provides a degradable epoxy resin containing a cyclic acetal structure. The structure of the degradable epoxy resin containing a cyclic acetal structure is shown below:

[0030]

[0031]

[0032] The present invention also provides a method for preparing the degradable epoxy resin containing a cyclic acetal structure, comprising the following steps:

[0033] (1) In a protective atmosphere, tetraol, 3-cyclohexene-1-carboxaldehyde, p-toluenesulfonic acid monohydrate and a solvent are mixed to undergo a nucleophilic addition reaction to obtain a bicyclic intermediate;

[0034] (2) Mixing the bicyclic intermediate solution, the epoxidation reagent solution and the alkaline solution to carry out epoxidation reaction, thereby obtaining the degradable epoxy resin containing the cyclic acetal structure.

[0035] In the present invention, the protective atmosphere in step (1) is preferably nitrogen, argon or helium.

[0036] In the present invention, the tetrahydric alcohol in step (1) is preferably pentaerythritol, erythritol or dipropylene glycol.

[0037] In the present invention, the solvent in step (1) is preferably one or more of petroleum ether, N,N-dimethylformamide, n-hexane, dichloromethane, tetrahydrofuran, acetone and butanone.

[0038] In the present invention, the molar ratio of the tetraol to 3-cyclohexene-1-carboxaldehyde in step (1) is preferably 1:2-3, more preferably 1:2.2-2.8, and even more preferably 1:2.4-2.6.

[0039] In the present invention, the mass of p-toluenesulfonic acid monohydrate in step (1) is preferably 1-3% of the total mass of tetraol and 3-cyclohexene-1-carboxaldehyde, more preferably 1.5-2.5%, and even more preferably 1.8-2.3%.

[0040] In the present invention, the solvent is used in excess in step (1).

[0041] In the present invention, in step (1), the raw materials are mixed and then heated to reflux temperature, and the nucleophilic addition reaction is carried out at the reflux temperature. The time of the nucleophilic addition reaction is preferably 12 to 24 hours, more preferably 14 to 22 hours, and more preferably 16 to 20 hours.

[0042] In the present invention, precipitation is performed after the nucleophilic addition reaction to obtain a precipitated product; the precipitating reagent is a sodium bicarbonate aqueous solution; the fraction of the sodium bicarbonate aqueous solution is preferably 1 to 5 wt%, more preferably 2 to 4 wt%, and more preferably 2.5 to 3 wt%; the precipitated product is filtered, washed, and dried in sequence; deionized water is used for washing, and the number of washings is preferably ≥5 times, more preferably ≥6 times, and more preferably ≥8 times; the drying temperature is preferably 70 to 90° C., more preferably 75 to 85° C., and more preferably 78 to 82° C., and the product is dried to constant weight to obtain a bicyclic intermediate.

[0043] In the present invention, when the tetrahydric alcohol selected is pentaerythritol, the bicyclic intermediate generated by the nucleophilic addition reaction is

[0044] In the present invention, when the tetrahydric alcohol selected is erythritol, the bicyclic intermediate generated by the nucleophilic addition reaction is

[0045] In the present invention, when the tetraol selected is dipropylene glycol, the bicyclic intermediate generated by the nucleophilic addition reaction is

[0046] In the present invention, the bicyclic intermediate solution in step (2) comprises a bicyclic intermediate, 18-crown-6-ether and a solvent.

[0047] In the present invention, the solvent is preferably one or more of dichloromethane, chloroform, tetrahydrofuran, N,N-dimethylformamide, methylpyrrolidone and acetone.

[0048] In the present invention, the molar volume ratio of the bicyclic intermediate, 18-crown-6-ether and solvent is preferably 1 mol: 0.1-0.2 mol: 5-7 L, more preferably 1 mol: 0.12-0.18 mol: 5.5-6.5 L, and more preferably 1 mol: 0.14-0.16 mol: 5.6-6.2 L.

[0049] In the present invention, the epoxidation reagent solution in step (2) comprises an epoxidation reagent, ethylenediaminetetraacetic acid and a solvent.

[0050] In the present invention, the epoxidation reagent is one or more of potassium persulfate complex salt, peracetic acid, peroxybenzoic acid, m-chloroperoxybenzoic acid, p-nitroperoxybenzoic acid and m-nitroperoxybenzoic acid.

[0051] In the present invention, the solvent is one or more of dichloromethane, chloroform, tetrahydrofuran, N,N-dimethylformamide, methyl pyrrolidone, acetone and water.

[0052] In the present invention, the molar volume ratio of the epoxidation reagent, ethylenediaminetetraacetic acid and solvent is preferably 250-260 mmol: 0.15-0.2 mmol: 250-300 mL, more preferably 252-258 mmol: 0.16-0.19 mmol: 260-290 mL, and more preferably 254-256 mmol: 0.17-0.18 mmol: 270-280 mL.

[0053] In the present invention, the molar ratio of the bicyclic intermediate to the epoxidation reagent in step (2) is preferably 1:7.5-10, more preferably 1:8-9.5, and even more preferably 1:8.5-9.

[0054] In the present invention, the concentration of the alkaline solution in step (2) is preferably 0.4-0.8M, more preferably 0.5-0.7M, and even more preferably 0.55-0.6M.

[0055] In the present invention, the alkaline solution is preferably a sodium hydroxide solution, a potassium hydroxide solution or a lithium hydroxide solution.

[0056] In the present invention, the pH value of the system after adding the alkaline solution is preferably 7 to 8, more preferably 7.2 to 7.8, and even more preferably 7.35 to 7.65.

[0057] In the present invention, the epoxidation reagent and the alkaline solution are added dropwise to the bicyclic intermediate solution. The temperature at the start of the addition is controlled as the temperature of the epoxidation reaction. After the addition is completed, the timing is started to carry out the epoxidation reaction.

[0058] In the present invention, the temperature of the epoxidation reaction in step (2) is preferably 0-5°C, more preferably 1-4°C, more preferably 2-3°C; the time is preferably 5-8h, more preferably 5.5-7.5h, more preferably 6-7h.

[0059] In the present invention, after the epoxidation reaction in step (2) is completed, the reaction system is washed with a saturated sodium carbonate aqueous solution, and the number of washings is preferably ≥3 times, more preferably ≥4 times, and more preferably ≥5 times; then a secondary washing is performed with deionized water, and the number of secondary washings is preferably ≥3 times, more preferably ≥4 times, and more preferably ≥5 times; after the washing is completed, the reaction system is dried to constant weight, and the drying temperature is preferably 70 to 90° C., more preferably 75 to 85° C., and more preferably 78 to 82° C.

[0060] In the present invention, when the bicyclic intermediate is When the epoxy resin produced by the epoxidation reaction is

[0061] In the present invention, when the bicyclic intermediate is When the epoxy resin produced by the epoxidation reaction is

[0062] In the present invention, when the bicyclic intermediate is When the epoxy resin produced by the epoxidation reaction is

[0063] The present invention also provides application of the degradable epoxy resin containing a cyclic acetal structure in degradable materials.

[0064] The present invention also provides an application method of the degradable epoxy resin containing a cyclic acetal structure, comprising the following steps:

[0065] The degradable epoxy resin containing a cyclic acetal structure, a curing agent and an accelerator are mixed and then vacuum degassing, pre-curing and curing are carried out in sequence.

[0066] In the present invention, the curing agent is preferably methylhexahydrophthalic anhydride.

[0067] In the present invention, the accelerator is preferably 1,8-diazobicyclo[5.4.0]-7-decene.

[0068] In the present invention, the molar ratio of epoxy groups to curing agents in the degradable epoxy resin containing a cyclic acetal structure is preferably 1:0.8-1.2, more preferably 1:0.9-1.1, and even more preferably 1:0.95-1.

[0069] In the present invention, the mass of the accelerator is preferably 0.2-1.5% of the total mass of the degradable epoxy resin containing a cyclic acetal structure, the curing agent and the accelerator, more preferably 0.4-1.3%, and even more preferably 0.6-1%.

[0070] In the present invention, the vacuum degassing time is preferably 0.5 to 1 h, more preferably 0.6 to 0.9 h, and even more preferably 0.7 to 0.8 h.

[0071] In the present invention, the pre-curing temperature is preferably 100-120° C., more preferably 105-115° C., more preferably 108-112° C.; the pre-curing time is preferably 1-2 h, more preferably 1.2-1.8 h, more preferably 1.4-1.6 h.

[0072] In the present invention, the curing is low-temperature curing and high-temperature curing performed sequentially.

[0073] In the present invention, the low-temperature curing temperature is preferably 150-170°C, more preferably 155-165°C, and more preferably 158-162°C; the curing time is preferably 2-3 hours, more preferably 2.2-2.8 hours, and more preferably 2.4-2.6 hours.

[0074] In the present invention, the high temperature curing temperature is preferably 170-190° C., more preferably 175-185° C., more preferably 178-182° C.; the curing time is preferably 1-2 h, more preferably 1.2-1.8 h, more preferably 1.4-1.6 h.

[0075] The technical solutions provided by the present invention are 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.

[0076] Example 1

[0077] 40 g (0.363 mol) of 3-cyclohexene-1-carboxaldehyde, 24.7 g (0.181 mol) of pentaerythritol, 1.294 g of p-toluenesulfonic acid monohydrate, 156 g of N,N-dimethylformamide, and 116 g of petroleum ether were added to a container and mixed uniformly; the mixture was reacted for 12 hours under the solvent reflux temperature, stirring conditions, and a nitrogen atmosphere; after the reaction, the mixture was precipitated with 500 mL of a 3 wt% aqueous sodium bicarbonate solution, the precipitated product was filtered, washed with deionized water 5 times, and dried in an oven at 80° C. for 5 hours to obtain the following bicyclic intermediate with a yield of 62%;

[0078]

[0079] 0.05 g (0.17 mmol) of ethylenediaminetetraacetic acid, 78.1 g (254 mmol) of potassium peroxydisulfate, and 275 ml of deionized water were added to a dropping funnel. In a container, 10 g (0.031 mol) of the above-mentioned bicyclic intermediate, 90 mL of dichloromethane, 90 mL of acetone, and 0.825 g (0.0031 mol) of 18-crown-6-ether were added. After mixing, the above-mentioned potassium peroxydisulfate solution and 0.6 M potassium hydroxide solution were added dropwise at 5°C with stirring, maintaining the pH value of the system at 7.7. After the addition was completed, the reaction was continued for 5 hours. After the reaction was completed, the resulting reaction solution was washed three times with a saturated sodium carbonate solution and three times with deionized water, and then dried in an oven at 80°C to obtain the following biodegradable epoxy resin containing a cyclic acetal structure with a yield of 87%.

[0080]

[0081] Structure and epoxy equivalent characterization:

[0082] Structural characterization: infrared spectroscopy, 1 The alicyclic epoxy resin monomer containing cyclic acetal structure was characterized by HNMR and elemental analysis.

[0083] Epoxy equivalent test: The epoxy equivalent of alicyclic epoxy resin monomers containing cyclic acetal structures was tested using the titration method according to the ASTM-D1652 test standard.

[0084] Infrared spectrum (potassium bromide tablet): 1009 cm -1 (CO); 1129cm -1 (CO); 1190cm -1 (CO); 908cm -1 (epoxy group);

[0085] 1 HNMR (DMSO-d6, ppmδ): 3.24 (4H, -CH- in the epoxy group), 1.38-1.84 (14H, -CH-, -CH2- on the six-membered ring), 5.6 (2H, -CH- on the acetal bond); 3.63-3.73 (8H, -CH2- on the spiro ring)

[0086] Elemental analysis: C 19 H 28 O6

[0087] Calculated values: C: 64.75%; H: 8.01%;

[0088] Measured values: C: 65.86%; H: 8.34%;

[0089] Epoxy equivalent weight: 176.

[0090] Example 2

[0091] 40 g (0.363 mol) of 3-cyclohexene-1-carboxaldehyde, 22.09 g (0.181 mol) of erythritol, 1.242 g of p-toluenesulfonic acid monohydrate, 156 g of N,N-dimethylformamide, and 116 g of petroleum ether were added to a container and mixed uniformly; the mixture was reacted for 12 hours under the solvent reflux temperature, stirring conditions, and a nitrogen atmosphere; after the reaction, the mixture was precipitated with 500 mL of a 3 wt% sodium bicarbonate aqueous solution, the precipitated product was filtered, washed with deionized water 5 times, and dried in an oven at 80° C. for 5 hours to obtain the following bicyclic intermediate with a yield of 72%;

[0092]

[0093] 0.05 g (0.17 mmol) of ethylenediaminetetraacetic acid, 78.1 g (254 mmol) of potassium peroxydisulfate, and 275 ml of deionized water were added to a dropping funnel. In a container, 10 g (0.0326 mol) of the aforementioned bicyclic intermediate, 90 mL of dichloromethane, 90 mL of acetone, and 0.862 g (0.00326 mol) of 18-crown-6-ether were added. After mixing, the potassium peroxydisulfate solution and 0.6 M potassium hydroxide solution were added dropwise at 5°C with stirring, maintaining the pH of the system at 8. After the addition, the reaction was continued for 5 hours. After the reaction was completed, the resulting reaction solution was washed three times with a saturated sodium carbonate solution and three times with deionized water, and then dried in an oven at 80°C to obtain the following biodegradable epoxy resin containing a cyclic acetal structure with a yield of 83%.

[0094]

[0095] Structure and epoxy equivalent characterization:

[0096] Test according to the method and standards in Example 1

[0097] Infrared spectrum (potassium bromide tablet): 1005 cm -1 (CO); 1129cm -1 (CO); 1188cm -1 (CO); 910cm -1 (epoxy group);

[0098] 1HNMR (DMSO-d6, ppmδ): 3.24 (4H, -CH- in the epoxy group), 1.38-1.86 (14H, -CH-, -CH2- on the six-membered ring), 5.5 (2H, -CH- on the acetal bond); 3.79-4.05 (6H, -CH2- on the bicyclic ring)

[0099] Elemental analysis: C 18 H 26 O6;

[0100] Calculated values: C: 63.89%; H: 7.74%;

[0101] Measured values: C: 65.87%; H: 7.93%;

[0102] Epoxy equivalent weight: 169.

[0103] Example 3

[0104] 40 g (0.363 mol) of 3-cyclohexene-1-carboxaldehyde, 30.08 g (0.181 mol) of dipropylene glycol, 1.40 g of p-toluenesulfonic acid monohydrate, 156 g of N,N-dimethylformamide, and 116 g of petroleum ether were added to a container and mixed uniformly; the mixture was reacted for 12 hours under the solvent reflux temperature, stirring conditions, and a nitrogen atmosphere; after the reaction, the mixture was precipitated with 500 mL of a 3 wt% aqueous sodium bicarbonate solution, the precipitated product was filtered, washed with deionized water 5 times, and dried in an oven at 80° C. for 5 hours to obtain the following bicyclic intermediate with a yield of 56%;

[0105]

[0106] 0.05 g (0.17 mmol) of ethylenediaminetetraacetic acid, 78.1 g (254 mmol) of potassium peroxydisulfate, and 275 ml of deionized water were added to a dropping funnel. In a container, 10 g (0.0285 mol) of the above-mentioned bicyclic intermediate, 90 mL of dichloromethane, 90 mL of acetone, and 0.753 g (0.00285 mol) of 18-crown-6-ether were added. After mixing, the above-mentioned potassium peroxydisulfate solution and 0.6 M potassium hydroxide solution were added dropwise at 5°C with stirring, maintaining the pH value of the system at 7.5. After the addition was completed, the reaction was continued for 5 hours. After the reaction was completed, the resulting reaction solution was washed three times with a saturated sodium carbonate solution and three times with deionized water, and then dried in an oven at 80°C to obtain the following biodegradable epoxy resin containing a cyclic acetal structure with a yield of 83%.

[0107]

[0108] Structure and epoxy equivalent characterization:

[0109] Test according to the method and standards in Example 1

[0110] Infrared spectrum (potassium bromide tablet): 1010 cm -1 (CO); 1132cm -1 (CO); 1189cm -1 (CO); 905cm -1 (epoxy group);

[0111] 1 HNMR (DMSO-d6, ppmδ): 3.24 (4H, -CH- in epoxy group), 1.38-1.86 (14H, -CH-, -CH2- on six-membered ring), 5.36 (2H, acetal bond -CH-); 3.62-4.12 (6H, -CH2- on five-membered ring); 3.15-3.60 (4H, -CH2-O-CH2)

[0112] Elemental analysis: C 20 H 30 O7;

[0113] Calculated values: C: 62.81%; H: 7.91%;

[0114] Measured values: C: 61.79%; H: 8.37%;

[0115] Epoxy equivalent weight: 191.

[0116] Comparative Example 1

[0117] Bisphenol A epoxy resin (NPEL-128, Nan Ya Resin) was used as a comparative example.

[0118] The epoxy resins prepared in Examples 1 to 3 and the epoxy resin in Comparative Example 1 were respectively mixed with a curing agent, methylhexahydrophthalic anhydride, wherein the molar ratio of epoxy groups to methylhexahydrophthalic anhydride in the epoxy resin was 1:1. 1%, by weight, of 1,8-diazobicyclo[5.4.0]-7-decene was then added as an accelerator. After stirring and mixing evenly, the resulting mixture was poured into a mold and degassed in a vacuum oven for 1 hour. Finally, the mixture was pre-cured at 120° C. for 1 hour, cured at 160° C. for 2 hours, and post-cured at 180° C. for 1 hour.

[0119] Tensile performance test: A universal mechanical testing machine was used to test the tensile properties of epoxy resin in accordance with the ASTM-D638 test standard.

[0120] Fracture toughness test: A universal mechanical testing machine was used to test the fracture toughness of epoxy resin according to the ASTM-5045 test standard, and the critical stress intensity factor (KIC) was calculated.

[0121] Glass transition temperature test: The glass transition temperature (Tg) of epoxy resin was tested using a dynamic mechanical analyzer. The test was conducted using a dual cantilever beam configuration with a heating rate of 3°C / min. The peak temperature of the loss tangent-temperature curve was taken as the glass transition temperature.

[0122] UV resistance test: Use a fluorescent UV lamp device and irradiate the cured epoxy resin under UV lamp for 12 hours according to ASTM G154 test standard, and observe the color of the epoxy resin.

[0123] Degradation performance test: At 25°C, 50 mg of sample was immersed in 10 mL of HCl solution. The HCl solution was prepared as follows: HCl concentration was 1 mol / L, the solvent was a mixture of acetone and water, and the volume ratio of acetone to water was 9:1. The time required for the sample to be completely degraded was recorded.

[0124] The tensile properties, fracture toughness, glass transition temperature, UV resistance and degradation properties of the cured products obtained after curing the epoxy resins of Examples 1 to 3 and Comparative Example 1 were tested, and the results are shown in Table 1.

[0125] Table 1 Test results

[0126] performance Example 1 Example 2 Example 3 Comparative Example 1 Tg(℃) 115 137 175 165 Tensile strength (MPa) 85 81 79 72 Tensile modulus (MPa) 2650 2455 2720 2645 <![CDATA[Fracture toughness KIC (MPa.m 1 / 2 )]]> 0.61 0.68 0.71 0.52 Color after UV aging White White White yellow Degradation time in acidic solution (min) 45 78 92 Non-degradable

[0127] It can be seen from the above examples that the degradable epoxy resin containing a cyclic acetal structure provided by the present invention not only has degradable properties, but also maintains excellent mechanical properties and thermal stability, and has good resistance to ultraviolet aging.

[0128] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A degradable epoxy resin containing a cyclic acetal structure, characterized in that: The structure of the degradable epoxy resin containing cyclic acetal structure is shown below:

2. The method for preparing the degradable epoxy resin containing a cyclic acetal structure according to claim 1, wherein: It includes the following steps: (1) In a protective atmosphere, tetraol, 3-cyclohexene-1-carboxaldehyde, p-toluenesulfonic acid monohydrate and a solvent are mixed to undergo a nucleophilic addition reaction to obtain a bicyclic intermediate; (2) Mixing the bicyclic intermediate solution, the epoxidation reagent solution and the alkaline solution to carry out epoxidation reaction, thereby obtaining the degradable epoxy resin containing the cyclic acetal structure.

3. The method for preparing a degradable epoxy resin containing a cyclic acetal structure according to claim 2, wherein: The tetrahydric alcohol in step (1) is pentaerythritol, erythritol or dipropylene glycol; The solvent in step (1) is one or more of petroleum ether, N,N-dimethylformamide, n-hexane, dichloromethane, tetrahydrofuran, acetone and butanone.

4. The method for preparing a degradable epoxy resin containing a cyclic acetal structure according to claim 3, wherein: The molar ratio of the tetraol to 3-cyclohexene-1-carboxaldehyde in step (1) is 1:2-3.

5. The method for preparing a degradable epoxy resin containing a cyclic acetal structure according to claim 4, wherein: The mass of p-toluenesulfonic acid monohydrate in step (1) is 1 to 3% of the total mass of tetraol and 3-cyclohexene-1-carboxaldehyde.

6. The method for preparing a degradable epoxy resin containing a cyclic acetal structure according to claim 5, wherein: The time of the nucleophilic addition reaction in step (1) is 12 to 24 hours.

7. The method for preparing a degradable epoxy resin containing a cyclic acetal structure according to claim 6, wherein: The bicyclic intermediate solution in step (2) comprises a bicyclic intermediate, 18-crown-6-ether and a solvent; The solvent is one or more of dichloromethane, chloroform, tetrahydrofuran, N,N-dimethylformamide, methyl pyrrolidone and acetone; The molar volume ratio of the bicyclic intermediate, 18-crown-6-ether and solvent is 1 mol: 0.1-0.2 mol: 5-7 L.

8. The method for preparing a degradable epoxy resin containing a cyclic acetal structure according to claim 7, wherein: The epoxidation reagent solution in step (2) comprises an epoxidation reagent, ethylenediaminetetraacetic acid and a solvent; The epoxidation reagent is one or more of potassium persulfate complex salt, peracetic acid, peroxybenzoic acid, m-chloroperoxybenzoic acid, p-nitroperoxybenzoic acid and m-nitroperoxybenzoic acid; The solvent is one or more of dichloromethane, chloroform, tetrahydrofuran, N,N-dimethylformamide, methyl pyrrolidone, acetone and water; The molar volume ratio of the epoxidation reagent, ethylenediaminetetraacetic acid and solvent is 250-260 mmol: 0.15-0.2 mmol: 250-300 mL.

9. The method for preparing a degradable epoxy resin containing a cyclic acetal structure according to claim 8, wherein: The molar ratio of the bicyclic intermediate to the epoxidation reagent in step (2) is 1:7.5-10; The concentration of the alkaline solution in step (2) is 0.4 to 0.8 M; The epoxidation reaction in step (2) is carried out at a temperature of 0 to 5° C. and for a time of 5 to 8 hours.

10. Use of the degradable epoxy resin containing a cyclic acetal structure according to claim 1 in degradable materials.

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