Phase transfer separation method of anhydride cured epoxy resin degradation product

Abstract

A phase transfer separation method of an anhydride cured epoxy resin degradation product comprises the following steps: adding anhydride cured epoxy resin into an alkaline degradation solution for degradation to obtain a degradation solution; adding ethanol into the degradation solution, standing to generate a precipitate, and collecting the precipitate by utilizing suction filtration; carrying out vacuum rotary evaporation on the solution subjected to suction filtration at 80 DEG C for 10 minutes to remove ethanol in the solution; adding water into the solution without the ethanol, standing for layering, and taking out a lower-layer oil phase; the method realizes complete degradation of the material under mild conditions, the recovered degradation product is separated by a phase transfer separation method, the separated product can be re-synthesized into a new epoxy resin insulating material, the problem that the insulating material in waste electrical equipment cannot be recovered and utilized in a green manner is solved, resources are effectively saved, the environment is protected, and the method is suitable for industrial production. The practical application value is realized.

Description

Technical Field

[0001] The invention relates to the technical field of epoxy resin degradation and recovery, and in particular to a phase transfer separation method for anhydride-cured epoxy resin degradation products. Background Art

[0002] Anhydride-cured epoxy resins are widely used in the field of insulation materials for electrical equipment such as dry-type transformers and voltage transformers due to their excellent insulation performance, good physical and chemical properties, and good stability after curing. However, most existing anhydride-cured epoxy insulation materials have a dense three-dimensional cross-linked structure, making it difficult to achieve effective degradation, which can easily lead to the overall abandonment of electrical equipment after retirement, and the inability to recycle metals and other materials inside the equipment, causing environmental pollution and waste of resources.

[0003] At present, the epoxy resin materials commonly used in the electrical field are mainly made of bisphenol A. However, in most cases, only a small part of the degradation products can be used to rebuild new epoxy thermosetting resins in the existing bisphenol A-based epoxy resin degradation and recycling methods, and the proportion of degradation products in new epoxy thermosetting resins is very low.

[0004] The most commonly used separation method for epoxy resin degradation products today is column chromatography. This method is not only cumbersome and difficult to use, but also has the disadvantages of unstable separation effect and the use of irritating and toxic reagents as solvents during the separation process. More importantly, this method is more used in the laboratory to separate small amounts of products and is not suitable for industrial production processes.

[0005] In view of the above, it is necessary to develop an upgrading and recycling method for anhydride-cured epoxy insulation materials, which can achieve the degradation and separation of materials under mild conditions while ensuring the excellent electrical properties of the materials, so as to achieve effective upgrading and recycling of materials. Summary of the invention

[0006] In order to solve the above problems, the present invention proposes a phase transfer separation method for anhydride-cured epoxy resin degradation products, and the specific technical scheme is as follows: A phase transfer separation method for anhydride-cured epoxy resin degradation products comprises the following steps: Degradation treatment: adding anhydride-cured epoxy resin into alkaline degradation solution for degradation to obtain a degradation solution; Precipitation treatment: adding ethanol to the degradation solution, allowing it to stand to generate precipitation, and collecting the precipitate by suction filtration; Rotary evaporation: vacuum evaporation the filtered solution at 80°C for 10 min to remove ethanol from the solution; Extraction treatment: Add water to the solution after removing ethanol, let it stand to separate the layers, and take out the lower oil phase.

[0007] Furthermore, the epoxy resin is pretreated before degradation, and the pretreatment process is: the epoxy resin is sealed and immersed in a dichloromethane solution, and then dried after the immersion is completed.

[0008] Furthermore, the degradation liquid is a mixed solution of ethylene glycol and sodium hydroxide.

[0009] Furthermore, the mass ratio of the epoxy resin to ethylene glycol and sodium hydroxide is 3:15 to 30:1.

[0010] Furthermore, the temperature of the degradation treatment is 150°C.

[0011] Furthermore, during the precipitation treatment, the volume ratio of the degradation solution to ethanol is 1:1-3.

[0012] Furthermore, during the extraction treatment, the volume ratio of the solution after removing the ethanol to the added water is 1:1-3.

[0013] Furthermore, the epoxy resin is synthesized from bisphenol A diglycidyl ether and methyltetrahydrophthalic anhydride under the action of accelerator DMP-30.

[0014] Furthermore, the molar ratio of bisphenol A diglycidyl ether to methyltetrahydrophthalic anhydride is 1:2.

[0015] Beneficial effects: The present invention realizes complete degradation of the material under mild conditions, and the recovered degradation products are separated by a phase transfer separation method. The separated products can be resynthesized into new epoxy resin insulating materials, thus solving the problem that insulating materials in discarded electrical equipment cannot be recycled and utilized greenly, effectively saving resources and protecting the environment, and having practical application value. DETAILED DESCRIPTION

[0016] The technical solutions in the embodiments of the present application are described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0017] Current research has found that there are a large number of ester bonds in anhydride-cured epoxy resins, which can undergo transesterification reactions with active hydroxyl groups, and an alkaline environment can accelerate the transesterification reaction, thereby achieving depolymerization and degradation of the cross-linked network. Therefore, a mixed solution of ethylene glycol and sodium hydroxide is used as a degradation agent.

[0018] A phase transfer separation method for anhydride-cured epoxy resin degradation products comprises the following steps: (1) Degradation treatment: The anhydride-cured epoxy resin is added to an alkaline degradation solution for degradation to obtain a degradation solution.

[0019] Wherein, the epoxy resin is pretreated before degradation, and the pretreatment process is: the epoxy resin is sealed and immersed in a dichloromethane solution, and then dried after the immersion is completed.

[0020] The degradation liquid is a mixed solution of ethylene glycol and sodium hydroxide, the mass ratio of the epoxy resin to ethylene glycol and sodium hydroxide is 3:15-30:1, and the temperature of the degradation treatment is 150°C.

[0021] (2) Precipitation treatment: adding ethanol to the degradation solution, allowing it to stand to generate precipitation, and collecting the precipitate by suction filtration.

[0022] Wherein, during the precipitation treatment, the volume ratio of the degradation solution to ethanol is 1:1-3; and the precipitate is a dicarboxylate.

[0023] (3) Rotary evaporation: The filtered solution was subjected to vacuum rotary evaporation at 80°C for 10 min to remove ethanol from the solution.

[0024] (4) Extraction treatment: Add water to the solution after removing ethanol, let it stand to separate the layers, and take out the lower oil phase.

[0025] During the extraction process, the volume ratio of the solution after the ethanol is removed to the added water is 1:1-3, and the lower oil phase is a polyol.

[0026] The epoxy resin is synthesized from bisphenol A diglycidyl ether and methyltetrahydrophthalic anhydride under the action of accelerator DMP-30; the molar ratio of bisphenol A diglycidyl ether to methyltetrahydrophthalic anhydride is 1:2.

[0027] The specific embodiments are as follows: Embodiment 1: (1) Material pretreatment The anhydride-cured epoxy resin insulating material prepared by using the accelerator DMP-30 is crushed to obtain the pretreated epoxy insulating material.

[0028] (2) Degradation process 3 g of the pretreated epoxy resin was put into ethylene glycol and sodium hydroxide solution for degradation, the mass ratio of epoxy resin to ethylene glycol and sodium hydroxide was 3:25:1, and heated in a sealed manner at 150°C until it was completely degraded.

[0029] (3) Separation process Add ethanol to the above degradation solution and let it stand for 2 hours to produce precipitation. Collect the solid precipitate by suction filtration, and then vacuum evaporate the filtered solution at 80°C for 10 minutes to remove ethanol in the solution. Finally, add water to the solution, let it stand for 24 hours, and remove the lower oil phase by layers.

[0030] The volume ratio of the degradation solution to ethanol is 1:1, and in the extraction process, the volume ratio of the solution after removing ethanol to the added water is 1:1.

[0031] Embodiment 2: In step (2) of Example 1, the mass ratio of the pretreated epoxy resin to ethylene glycol is changed to 3:15, and the separation of the epoxy resin chemical degradation products is carried out according to the above steps.

[0032] Embodiment 3: In step (2) of Example 1, the mass ratio of the pretreated epoxy resin to ethylene glycol is changed to 3:30, and the separation of the epoxy resin chemical degradation products is carried out according to the above steps.

[0033] The data of each embodiment are shown in the following table:

[0034] According to the above embodiments and experimental test data, the volume ratio of the treated epoxy resin material to ethylene glycol is 3:25, which is more suitable, and the degradation rate is as high as 97%, and the amount of ethylene glycol is moderate.

[0035] Embodiment 4: In step (3) of Example 1, the volume ratio of the solution after removing ethanol to the added water is changed to 1:2, and the epoxy resin chemical degradation products are separated according to the above steps.

[0036] Embodiment 5: In step (3) of Example 1, the volume ratio of the solution after removing ethanol to the added water is changed to 1:3, and the epoxy resin chemical degradation products are separated according to the above steps.

[0037] The data of each embodiment are shown in the following table:

[0038] According to the above examples and experimental test data, the volume ratio of the solution after ethanol removal to the added water is more suitable when it is 1:2. Under this condition, the separated degradation product dicarboxylate is the largest.

[0039] Embodiment 6: In step (3) of Example 4, the volume ratio of the solution after removing ethanol to the added water is changed to 1:2, and the epoxy resin chemical degradation products are separated according to the above steps.

[0040] Embodiment 7: In step (3) of Example 4, the volume ratio of the solution after removing ethanol to the added water is changed to 1:3, and the epoxy resin chemical degradation products are separated according to the above steps.

[0041]

[0042] According to the above examples and experimental test data, the volume ratio of the solution after ethanol removal to the added water is more suitable when it is 1:2. Under this condition, the most separated degradation product polyols.

[0043] In summary, as a preferred method, in the degradation process, the mass ratio of the pretreated epoxy resin to ethylene glycol is 3:25; in the separation process, the volume ratio of the degradation solution to ethanol is 1:2, and the volume ratio of the solution after removing ethanol and the added water during extraction is replaced with 1:2. In terms of the optimal time and efficiency of degradation, the ethylene glycol used in this ratio is optimal; in terms of the optimal efficiency of separating degradation products, the ethanol and water used in this ratio are optimal.

[0044] Unless otherwise specified, the raw materials used in the present invention are commonly available in the market.

[0045] In particular, the accelerator 2,4,6-(dimethylaminomethyl)triphenol (DMP-30) was purchased from Shanghai Anage Chemical Co., Ltd.; dichloromethane and sodium hydroxide were purchased from Chengdu Cologne Chemical Co., Ltd.; bisphenol A diglycidyl ether was purchased from Shanghai Lingfeng Chemical Reagent Co., Ltd.; methyltetrahydrophthalic anhydride was purchased from Shanghai Kaishu Chemical Technology Co., Ltd.; ethanol and ethylene glycol were purchased from Sinopharm Chemical Reagent Co., Ltd.; a rotary evaporator was purchased from Zhengzhou Great Wall Science and Technology Co., Ltd., a blast drying oven was purchased from Shanghai Yiheng Scientific Instrument Co., Ltd., and a pulverizer was purchased from Deqing Xieda E-Commerce Co., Ltd.

[0046] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A phase transfer separation method for anhydride-cured epoxy resin degradation products, characterized in that: The following steps are involved: Degradation treatment: adding anhydride-cured epoxy resin into alkaline degradation solution for degradation to obtain a degradation solution; Precipitation treatment: adding ethanol to the degradation solution, allowing it to stand to generate precipitation, and collecting the precipitate by suction filtration; Rotary evaporation: vacuum evaporation the filtered solution at 80°C for 10 min to remove ethanol from the solution; Extraction treatment: Add water to the solution after removing ethanol, let it stand to separate the layers, and take out the lower oil phase.

2. The method according to claim 1, characterized in that The epoxy resin is pretreated before degradation, and the pretreatment process is: the epoxy resin is sealed and immersed in a dichloromethane solution, and then dried after the immersion is completed.

3. The method according to claim 2, characterized in that The degradation liquid is a mixed solution of ethylene glycol and sodium hydroxide.

4. The method according to claim 3, characterized in that The mass ratio of the epoxy resin to ethylene glycol and sodium hydroxide is 3:15 to 30:

1.

5. The method according to claim 4, characterized in that The temperature of the degradation treatment was 150°C.

6. The method according to claim 1, characterized in that During the precipitation treatment, the volume ratio of the degradation solution to ethanol is 1:1-3.

7. The method according to claim 1, characterized in that During the extraction treatment, the volume ratio of the solution after removing ethanol to the added water is 1:1-3.

8. The method according to claim 1, characterized in that The epoxy resin is synthesized from bisphenol A diglycidyl ether and methyltetrahydrophthalic anhydride under the action of accelerator DMP-30.

9. The method according to claim 8, characterized in that The molar ratio of bisphenol A diglycidyl ether to methyltetrahydrophthalic anhydride is 1:2.

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