A biodegradable epoxy resin composition, cured product and its application

Abstract

This invention provides a biodegradable epoxy resin composition, a cured product, and its applications. The biodegradable epoxy resin composition comprises an oxalate-based polyester polyol, an ester-bonded epoxy resin, and a cationic initiator, wherein the mass ratio of the oxalate-based polyester polyol, the ester-bonded epoxy resin, and the cationic initiator is 20–50:50–80:5–10; the structure of the oxalate-based polyester polyol is shown in Formula I, wherein R1 and R2 are independently selected from C2–C4. 12 The epoxy resin composition contains aliphatic chain groups or aliphatic ring groups. The cured product formed by the biodegradable epoxy resin composition has excellent biodegradability, can be degraded in low-concentration alkaline aqueous solutions or seawater, and also has good thermodynamic properties.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of thermosetting resin, and particularly relates to a degradable epoxy resin composition, a degradable epoxy resin cured product and application thereof. BACKGROUND

[0002] Epoxy resin is one of the important thermosetting resins, which has been widely used in the fields of automobile manufacturing, aerospace, wind power generation and electrical appliances due to its excellent adhesive properties, electrical insulation properties, chemical stability and mechanical properties. However, the ordinary epoxy resin cured product cannot be reprocessed by heating or solvent dissolution, and is more difficult to degrade and recycle. After being discarded, it can only be treated by landfill, crushing, strong oxidation, strong acid / alkali degradation and the like, which not only wastes resources but also causes serious environmental pollution problems. In recent years, the mild degradation and recycling of epoxy resin have become an important research direction and received extensive attention from the academic and industrial circles.

[0003] It has been found that the degradation of epoxy resin under specific stimuli (such as heating, light, pH or catalyst) can be realized based on dynamic covalent chemistry, so as to realize the recycling of epoxy resin. Inspired by this, domestic and foreign scholars introduce dynamic covalent bonds into the crosslinking network of epoxy resin to prepare a series of novel materials with excellent degradation performance. However, the degradation process of epoxy resin using dynamic bonds often needs to consume a large amount of solvent and can only be carried out at a specific temperature, which leads to relatively high energy consumption in the degradation process, thereby hindering the wide application of degradable resin in the industrial field. SUMMARY

[0004] To solve all or part of the above technical problems, the present application provides the following technical solutions:

[0005] One of the purposes of the present application is to provide a degradable epoxy resin composition, which comprises oxalic polyester polyol, ester bond-containing epoxy resin and cationic initiator, and the mass ratio of the oxalic polyester polyol, ester bond-containing epoxy resin and cationic initiator is 20-50:50-80:5-10.

[0006] The structure of the oxalic polyester polyol is shown in formula I:

[0007]

[0008] wherein R1, R2 are independently selected from C2-C 12 fatty chain group or a fatty ring group.

[0009] The present application takes carbon dioxide compound oxalic acid as a starting point, and a series of degradable epoxy resin compositions are obtained by ring-opening chain transfer reaction of oxalic acid polyester polyol and ester-containing epoxy resin in the presence of a cationic initiator. The oxalic acid ester structure in the oxalic acid polyester molecular chain segment has a special adjacent carbonyl structure, which has a strong electron-withdrawing effect, thereby being endowed with excellent degradation ability. The copolymerization of the epoxy resin containing ester bond with oxalic acid ester obtains a crosslinked network system containing different ester bonds, and the degradation of oxalic acid ester will drive the degradation of other types of ester bonds. Therefore, the cured product of the resin composition can be degraded in low-concentration alkaline aqueous solution, and can also be naturally degraded in seawater, and has excellent degradable performance. Moreover, the cured product of the resin composition has excellent thermodynamic performance, and is suitable for high-end application fields with high strength and rapid degradation requirements for polymer materials.

[0010] In some embodiments, the molecular weight of the oxalic acid polyester polyol is 2000-50000 g / mol.

[0011] In some typical embodiments, the oxalic acid polyester polyol comprises one or a combination of the following compounds I-1, I-2, I-3, I-4, I-5, I-6, but is not limited thereto:

[0012]

[0013] In some embodiments, the ester-containing epoxy resin comprises an epoxy resin having a structure shown in formula II and / or an epoxy resin having a structure shown in formula III:

[0014]

[0015] wherein V, Y are C2-C 12 fatty chain group or fatty ring group.

[0016] In some embodiments, the ester-containing epoxy resin comprises one or a combination of the following epoxy resins II-1, II-2, II-3, III-1, III-2, but is not limited thereto:

[0017]

[0018] In some embodiments, the cationic initiator comprises a cationic photoinitiator and / or a cationic thermal initiator.

[0019] In some embodiments, the cationic photoinitiator comprises one or a combination of diazonium salt, diaryliodonium salt, triarylsulfonium salt, alkylsulfonium salt, iron arene salt, sulfonyloxy ketone or triarylsilyl ether, but is not limited thereto.

[0020] In some embodiments, the cationic thermal initiator includes one or a combination of antimonate, phosphate, alkyl ammonium salt, aryl diazonium salt, or onium salt, but is not limited thereto.

[0021] A second object of the present application is to provide use of the degradable epoxy resin composition in preparing wind power composite materials, electronic consumer products, electronic packaging, or electrical engineering resins.

[0022] A third object of the present application is to provide a degradable epoxy resin cured product formed by thermal curing or photocuring of the degradable epoxy resin composition.

[0023] In some embodiments, the method of thermal curing includes curing the degradable epoxy resin composition at a temperature of 50-100°C for 3-6 hours.

[0024] In some embodiments, the method of photocuring includes irradiating the degradable epoxy resin composition under ultraviolet light for 5-10 minutes. The ultraviolet light is, for example, 365 nm ultraviolet light.

[0025] In some embodiments, the degradable epoxy resin cured product can be degraded in an alkaline aqueous solution or seawater; in an alkaline aqueous solution at 25-100°C, the degradation rate of the degradable epoxy resin cured product is ≥99% within 2-48 hours; in seawater at 25°C, the degradation rate of the degradable epoxy resin cured product is ≥99% within 300-900 days.

[0026] In some embodiments, the glass transition temperature of the degradable epoxy resin cured product is 50-150°C, the tensile strength is 50-110 MPa, and the unnotched impact strength is 30-60 kJ / m 2 .

[0027] A fourth object of the present application is to provide a device with a degradable structure, wherein the degradable structure of the device includes the degradable epoxy resin cured product.

[0028] A fifth object of the present application is to provide a degradation method of the degradable epoxy resin cured product, which includes soaking the degradable epoxy resin cured product in an alkaline solution to degrade it, or placing it in seawater for natural degradation.

[0029] In some embodiments, the pH value of the alkaline solution is 9-14.

[0030] In some embodiments, the soaking time in the alkaline solution is 2-48 hours.

[0031] In some embodiments, the temperature of the alkaline solution is above 25°C, preferably 25-100°C.

[0032] Compared with the prior art, the present invention has at least the following beneficial effects:

[0033] (1) This invention takes carbon dioxide compound oxalate as the starting point and utilizes the ring-opening chain transfer reaction between oxalate polyester polyol and ester-containing epoxy resin in the presence of a cationic initiator to obtain a series of degradable epoxy resin compositions. The resin materials obtained by curing have both excellent thermodynamic properties and degradability, and are suitable for high-end application fields with high strength requirements and rapid degradation requirements for polymer materials.

[0034] (2) Compared with other biodegradable epoxy resin systems containing dynamic bonds, oxalate has the advantages of low price, abundant sources and simple synthesis process, so the preparation cost of the resin composition is low; based on the excellent degradation performance of the biodegradable epoxy resin, it can be degraded in a low concentration alkaline solution and a relatively mild temperature condition, and the required degradation time is short; or it can be naturally degraded using abundant seawater resources, with basically no other energy consumption required, thus solving the problem of high energy consumption and resource waste required for the degradation of epoxy resin in the prior art;

[0035] (3) The resin composition provided by the present invention has a simple preparation method, is easy to operate, has controllable reaction conditions, is easy to implement, and is suitable for large-scale industrial production. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is the NMR spectrum of the oxalic acid polyester polyol used in the biodegradable resin composition of Example 1 of the present invention.

[0038] Figure 2 This is the NMR spectrum of the oxalic acid polyester polyol used in the biodegradable resin composition of Example 2 of the present invention.

[0039] Figure 3 This is the NMR spectrum of the oxalic acid polyester polyol used in the biodegradable resin composition of Example 3 of the present invention. Detailed Implementation

[0040] The technical solutions of the present invention will be described in detail below with reference to specific embodiments, so that those skilled in the art can better understand and implement the technical solutions of the present invention. The specific functional details disclosed herein should not be construed as limiting, but are merely intended to form the basis of the claims and to teach those skilled in the art to employ the representative basis of the invention in different ways in any suitable detailed embodiment.

[0041] In addition, unless otherwise specified, all raw materials used in the following embodiments can be purchased from the market or other sources, and all production and testing equipment used are known in the art.

[0042] In the specific embodiments of the present invention, the test method for the glass transition temperature of the biodegradable epoxy resin cured product is in accordance with ASTM E1545-22; the test method for tensile strength is in accordance with GB / T 2567-2021; and the test method for unnotched impact strength is in accordance with GB / T2567-2021.

[0043] The test method for the degradation rate of biodegradable epoxy resin cured products in alkaline aqueous solutions and seawater is as follows: The cured product is ground into powder and then placed in an alkaline solution or seawater for degradation reaction. After degradation, the solution is filtered, the filter cake is dried, and the degradation rate of the cured powder is analyzed. Degradation rate (%) = (1 - mass of dried filter cake / mass of cured powder) * 100%).

[0044] The oxalic acid polyester polyol used in the following specific embodiments was prepared in accordance with the prior art CN202111088640.9.

[0045] Example 1

[0046] This embodiment provides a biodegradable epoxy resin composition, which is obtained by uniformly mixing oxalic acid polyester polyol, epoxy resin and iron aromatic salt photoinitiator (I-261) in a mass ratio of 20:80:5;

[0047] The oxalic acid polyester polyol used in this embodiment has the following structure:

[0048]

[0049] Figure 1 This is the NMR spectrum of the oxalic acid polyester polyol used in this embodiment;

[0050] The epoxy resin used in this embodiment has the following structure:

[0051]

[0052] The above-mentioned biodegradable epoxy resin composition was irradiated under 365nm ultraviolet light for 10 minutes to obtain a biodegradable epoxy resin cured product.

[0053] The properties of the prepared epoxy resin cured product were tested, and the results showed that the glass transition temperature of the biodegradable epoxy resin cured product was 115℃, the tensile strength was 58MPa, and the unnotched impact strength was 40kJ / m. 2 0.5M OH in an alkaline aqueous solution at 35℃ - The degradation rate is 99% after 48 hours, and reaches 99% after 198 days in seawater at 25℃.

[0054] Example 2

[0055] This embodiment provides a biodegradable epoxy resin composition, which is obtained by uniformly mixing oxalic acid polyester polyol, epoxy resin and diaryl iodine salt photoinitiator (4,4′-diacetamidophenyl iodine hexafluorophosphate) in a mass ratio of 30:70:6.

[0056] The oxalic acid polyester polyol used in this embodiment has the following structure:

[0057]

[0058] Figure 2 This is the NMR spectrum of the oxalic acid polyester polyol used in this embodiment;

[0059] The epoxy resin used in this embodiment has the following structure:

[0060]

[0061] The above-mentioned biodegradable epoxy resin composition was irradiated under 365nm ultraviolet light for 8 minutes to obtain a biodegradable epoxy resin cured product.

[0062] The properties of the prepared epoxy resin cured product were tested. The test results showed that the glass transition temperature of the biodegradable epoxy resin cured product was 112℃, the tensile strength was 65MPa, and the unnotched impact strength was 45kJ / m. 2 0.2M OH in an alkaline aqueous solution at 85℃ - The degradation rate is 99% in 24 hours and reaches 99% in seawater at 25℃ after 275 days.

[0063] Example 3

[0064] This embodiment provides a biodegradable epoxy resin composition, which is obtained by uniformly mixing oxalic acid polyester polyol, epoxy resin and iron aromatic salt photoinitiator (I-262) in a mass ratio of 40:60:10.

[0065] The oxalic acid polyester polyol used in this embodiment has the following structure:

[0066]

[0067] Figure 3 This is the NMR spectrum of the oxalic acid polyester polyol used in this embodiment;

[0068] The epoxy resin structure used in this embodiment is as follows:

[0069]

[0070] The above-mentioned biodegradable epoxy resin composition was irradiated under 365nm ultraviolet light for 5 minutes to obtain a biodegradable epoxy resin cured product.

[0071] The relevant properties of the prepared biodegradable epoxy resin cured product were tested. The test results showed that the glass transition temperature of the biodegradable epoxy resin cured product was 102℃, the tensile strength was 71MPa, and the unnotched impact strength was 55kJ / m. 2 1.0 M OH in an alkaline aqueous solution at 25°C - The degradation rate is 99% after 48 hours, and reaches 99% after 298 days in seawater at 25℃.

[0072] Example 4

[0073] Example 4 provides a biodegradable epoxy resin composition, which is obtained by uniformly mixing oxalic acid polyester polyol, epoxy resin and triaryl thioonium salt photoinitiator (S-phenyl-S-(2-benzoazole)-S-[4-(S-2-benzopurazole)phenyl]thiotrifluoromethanesulfonate) in a mass ratio of 35:75:5.

[0074] The oxalic acid polyester polyol structure used in this embodiment is as follows:

[0075]

[0076] The epoxy resin structure used in this embodiment is as follows:

[0077]

[0078] The above-mentioned biodegradable epoxy resin composition was irradiated under 365nm ultraviolet light for 10 minutes to obtain a biodegradable epoxy resin cured product.

[0079] The relevant properties of the cured biodegradable epoxy resin were tested. The test results showed that the glass transition temperature of the cured biodegradable epoxy resin was 136℃, the tensile strength was 75MPa, and the unnotched impact strength was 52kJ / m. 2 0.9M OH in an alkaline aqueous solution at 100℃ - The degradation rate is 99% in 24 hours and reaches 99% in seawater at 25℃ after 600 days.

[0080] Example 5

[0081] This embodiment provides a biodegradable epoxy resin composition, which is obtained by uniformly mixing oxalic acid polyester polyol, epoxy resin and alkyl ammonium salt thermal initiator (alkyl dimethyl ammonium chloride) in a mass ratio of 30:70:5.

[0082] The oxalic acid polyester polyol used in this embodiment has the following structure:

[0083]

[0084] The epoxy resin structure used in this embodiment is as follows:

[0085]

[0086] The above-mentioned biodegradable epoxy resin composition was cured at 80°C for 6 hours to obtain a biodegradable epoxy resin cured product.

[0087] The relevant properties of the prepared biodegradable epoxy resin cured product were tested. The test results showed that the glass transition temperature of the biodegradable epoxy resin cured product was 116℃, the tensile strength was 69MPa, and the unnotched impact strength was 57kJ / m. 2 0.8M OH in an alkaline aqueous solution at 100℃ - The degradation rate is 99% after 40 hours, and reaches 99% after 850 days in seawater at 25℃.

[0088] Example 6

[0089] This embodiment provides a biodegradable epoxy resin composition, which is obtained by uniformly mixing oxalic acid polyester polyol, epoxy resin and antimonate thermal initiator (N-benzylpyrazine hexafluoroantimonate) in a mass ratio of 40:60:8.

[0090] The oxalic acid polyester polyol used in this embodiment has the following structure:

[0091]

[0092] The epoxy resin used in this embodiment has the following structure:

[0093]

[0094] The above-mentioned biodegradable epoxy resin composition was cured at 90°C for 4 hours to obtain a biodegradable epoxy resin cured product.

[0095] The relevant properties of the obtained epoxy resin cured product were tested. The test results showed that the glass transition temperature of the biodegradable epoxy resin cured product was 85℃, the tensile strength was 62MPa, and the unnotched impact strength was 49kJ / m.2 1.0M OH in an alkaline aqueous solution at 65℃ - The degradation rate is 99% after 48 hours, and reaches 99% after 360 days in seawater at 25℃.

[0096] Example 7

[0097] Example 7 provides a biodegradable epoxy resin composition, which is obtained by uniformly mixing oxalic acid polyester polyol, epoxy resin and triaryl thioonium salt photoinitiator (S-phenyl-S-(2-benzoazole)-S-[4-(S-2-benzopurazole)phenyl]thiotrifluoromethanesulfonate) in a mass ratio of 35:75:5.

[0098] The oxalic acid polyester polyol structure used in this embodiment is as follows:

[0099]

[0100] The epoxy resin structure used in this embodiment is as follows:

[0101]

[0102] The above-mentioned biodegradable epoxy resin composition was irradiated under 365nm ultraviolet light for 10 minutes to obtain a biodegradable epoxy resin cured product.

[0103] The relevant properties of the cured biodegradable epoxy resin were tested. The test results showed that the glass transition temperature of the cured biodegradable epoxy resin was 86℃, the tensile strength was 52MPa, and the unnotched impact strength was 60kJ / m. 2 0.2M OH in an alkaline aqueous solution at 100℃ - The degradation rate is 99% after 48 hours, and reaches 99% after 900 days in seawater at 25℃.

[0104] Example 8

[0105] This embodiment provides a biodegradable epoxy resin composition, which is obtained by uniformly mixing oxalic acid polyester polyol, epoxy resin and antimonate thermal initiator (N-benzylpyrazine hexafluoroantimonate) in a mass ratio of 40:60:8.

[0106] The oxalic acid polyester polyol used in this embodiment has the following structure:

[0107]

[0108] The epoxy resin used in this embodiment has the following structure:

[0109]

[0110] The above-mentioned biodegradable epoxy resin composition was cured at 80°C for 6 hours to obtain a biodegradable epoxy resin cured product.

[0111] The relevant properties of the obtained epoxy resin cured product were tested. The test results showed that the glass transition temperature of the biodegradable epoxy resin cured product was 121℃, the tensile strength was 81MPa, and the unnotched impact strength was 41kJ / m. 2 1.0M OH in an alkaline aqueous solution at 85℃ - The degradation rate is 99% after 48 hours, and reaches 99% after 900 days in seawater at 25℃.

[0112] Comparative Example 1

[0113] Comparative Example 1 uses commercial polyester polyol (hexyl adipate), epoxy resin and diazonium fluoroborate initiator mixed uniformly in a mass ratio of 20:80:5 to obtain an epoxy resin composition.

[0114] The epoxy resin used in Comparative Example 1 has the following structure:

[0115]

[0116] The epoxy resin composition was irradiated under 365nm ultraviolet light for 10 minutes to obtain an epoxy resin cured product.

[0117] The relevant properties of the epoxy resin cured product were tested using the same method as in Example 1. The test results showed that the glass transition temperature of the epoxy resin cured product was 105℃, the tensile strength was 51MPa, and the unnotched impact strength was 37kJ / m. 2 The degradation rate was 0% within 48 hours in an alkaline aqueous solution of 1.0M OH at 25℃, and 0% within 900 days in seawater at 25℃.

[0118] Comparative Example 2

[0119] The only difference between Comparative Example 2 and Example 1 is that Comparative Example 2 uses an epoxy resin that does not contain ester bonds, specifically bisphenol A type epoxy resin E51. The rest of the procedures are the same as in Example 1. The relevant properties of the obtained epoxy resin cured product are as follows: glass transition temperature of 95°C, tensile strength of 61 MPa, and unnotched impact strength of 30 kJ / m. 2 0.5M OH in an alkaline aqueous solution at 35℃ - The degradation rate is 40% within 48 hours, and 25% within 198 days in seawater at 25°C.

[0120] Compared with Example 1 and Comparative Example 2, the epoxy resin cured product made with ester-containing epoxy resin contains more ester bonds, which enables the cured product to have a faster degradation rate and more complete degradation.

[0121] In summary, this invention utilizes the unique degradation properties of oxalate ester structures to develop a series of novel biodegradable epoxy resin compositions. These compositions not only undergo natural degradation in seawater but also rapidly decompose in low-concentration alkaline aqueous solutions. These resin compositions have broad application prospects in the fields of composite materials and encapsulating resins, indicating that the practical application of biodegradable epoxy resins will enter a new stage of development, and is expected to truly propel this field towards a more environmentally friendly and sustainable direction.

[0122] All aspects, embodiments, features, and examples of this invention are to be regarded as illustrative in all respects and are not intended to limit the invention, the scope of which is defined only by the claims. Other embodiments, modifications, and uses will become apparent to those skilled in the art without departing from the spirit and scope of the invention as claimed.

[0123] In addition, the inventors of this case also conducted experiments with other raw materials, process operations, and process conditions described in this specification, referring to the aforementioned embodiments, and obtained relatively ideal results in all cases.

[0124] Although the invention has been described with reference to illustrative embodiments, those skilled in the art will understand that various other changes, omissions, and / or additions can be made without departing from the spirit and scope of the invention, and that elements of the embodiments can be substituted with substantially equivalents. Furthermore, many modifications can be made without departing from the scope of the invention to adapt particular situations or materials to the teachings of the invention. Therefore, this invention is not intended to be limited to the specific embodiments disclosed for carrying out the invention, but rather is intended to encompass all embodiments falling within the scope of the appended claims. Moreover, unless specifically stated otherwise, any use of the terms first, second, etc., does not indicate any order or importance, but is used to distinguish one element from another.

Claims

1. A degradable epoxy resin composition, characterized by, The oxalic polyester polyol, the ester bond-containing epoxy resin and the cationic initiator have a mass ratio of 20-50:50-80:5-10. The oxalic polyester polyol has a structure as shown in Formula I and a molecular weight of 2000-50000 g / mol. ； wherein R1, R2are independently selected from C2-C 12 aliphatic chain groups or aliphatic ring groups; The ester bond-containing epoxy resin comprises an epoxy resin having a structure as shown in Formula II and / or an epoxy resin having a structure as shown in Formula III. ； wherein X, Y are C2-C 12 fatty chain group or a fatty ring group.

2. The degradable epoxy resin composition according to claim 1, characterized in that: The cationic initiator comprises a cationic photoinitiator and / or a cationic thermal initiator.

3. The degradable epoxy resin composition according to claim 2, characterized in that: The cationic photoinitiator comprises one or a combination of diazonium salts, diaryliodonium salts, triarylsulfonium salts, alkylsulfonium salts, iron arene salts, sulfonyloxy ketones or triarylsilyl ethers.

4. The degradable epoxy resin composition according to claim 2, characterized in that: The cationic thermal initiator comprises one or a combination of antimonate salts, phosphate salts, alkylammonium salts, aryl diazonium salts or onium salts.

5. Use of the degradable epoxy resin composition according to any one of claims 1-4 in the preparation of a wind power composite material, an electronic consumer product, an electronic package or an electrical engineering resin.

6. A degradable epoxy resin cured product, characterized by: The degradable epoxy resin cured product is formed by thermal curing or photocuring of the degradable epoxy resin composition according to any one of claims 1-4.

7. The degradable epoxy resin cured product according to claim 6, wherein The method of thermal curing comprises curing the degradable epoxy resin composition at a temperature of 50-100°C for 3-6 hours.

8. The degradable epoxy resin cured product according to claim 6, wherein The method of photocuring comprises irradiating the degradable epoxy resin composition under ultraviolet light for 5-10 minutes.

9. The degradable epoxy resin cured product according to claim 6, wherein The degradable epoxy resin cured product can be degraded in an alkaline aqueous solution or seawater; in an alkaline aqueous solution at 25-100°C, the degradation rate of the degradable epoxy resin cured product is ≥99% within 2-48 hours; in seawater at 25°C, the degradation rate of the degradable epoxy resin cured product is ≥99% within 300-900 days.

10. The degradable epoxy resin cured product according to claim 6, wherein The glass transition temperature of the degradable epoxy resin cured product is 50-150℃, the tensile strength is 50-110 MPa, and the unnotched impact strength is 30-60 kJ / m 2 .

11. An apparatus having a degradable structure, characterized by: The degradable structure of the device comprises the degradable epoxy resin cured product according to any one of claims 7-10.

12. A method of degrading a degradable epoxy resin cured product, characterized by, comprises: The degradable epoxy resin cured product according to any one of claims 7-10 is immersed in an alkaline solution to degrade or is naturally degraded in seawater.

13. The method of degrading a degradable epoxy resin cure according to claim 12, wherein: The pH value of the alkaline solution is 9-14.

14. The method of degrading a degradable epoxy resin cure of claim 12, wherein: The immersion time in the alkaline solution is 2-48 hours.

15. The method of degrading a degradable epoxy resin cure of claim 12, wherein: The temperature of the alkaline solution is above 25°C.

16. The method of degrading a degradable epoxy resin cure according to claim 15, wherein: The temperature of the alkaline solution is 25-100°C.

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