Method for catalytically degrading polyimide by using ionic liquid

Abstract

The invention provides a method for catalytic degradation of polyimide by ionic liquid, and belongs to the technical field of waste plastic recycling and recycling. The method comprises the following steps: uniformly mixing an ionic liquid catalyst, polyimide, water and an organic solvent, and then carrying out hydrolysis reaction; the ionic liquid catalyst is a compound with a structure as shown in a formula I or a formula II: # imgabs0 #, wherein R1 is alkyl, nitrile alkyl, hydroxyalkyl, ester group or ether group; r2 is nitrile alkyl, hydroxyalkyl, ester group, ether group or alkyl, and R3 is C1-C3 alkyl; y <-> is Cl <->, Br <->, OAc <->, CH3CH2COO <->, CF3COO <-> or (CF3SO2) 2N <->. The method takes the ionic liquid as the catalyst, has the advantages of mild reaction conditions (such as 100 DEG C), simple separation and the like, can efficiently catalyze the hydrolysis reaction of the waste polyimide, and has a relatively wide industrial application prospect.

Description

Technical Field

[0001] The invention relates to the technical field of recycling and resource recovery of waste plastics, and in particular to a method for catalyzing the degradation of polyimide using ionic liquids. Background Art

[0002] Polyimide refers to a polymer with an imide group (─CO─N─CO─) in the main chain. It has excellent heat resistance, chemical corrosion resistance, good mechanical properties, excellent thermal stability and other properties. It is widely used in photoresists, separation membranes, aerospace and microelectronics industries. The demand for polyimide is growing with the development of related industries. However, a lot of waste is generated during the production and use of polyimide. The use of traditional incineration or landfill treatment methods will cause waste of resources and environmental pollution. Therefore, from the perspective of environmental protection and sustainable development, the recycling of polyimide deserves attention.

[0003]

[0004] Given the high bond energy characteristics of the amide bond in polyimide, the effective cleavage of the amide carbon-nitrogen bond usually needs to be carried out in an alkaline environment, that is, the polyimide is treated with a strong base to achieve the hydrolytic cleavage of the polyimide five-membered ring. The use of strong bases in this process will corrode the equipment and the degradation efficiency is not high. Therefore, in order to comply with the requirements of contemporary green and sustainable development, it is urgent to develop a simple, efficient and multifunctional catalyst to achieve efficient degradation of polyimide. Summary of the invention

[0005] Based on the above content, the purpose of the present invention is to provide a method for catalyzing the degradation of polyimide using ionic liquids. The present invention uses ionic liquids as catalysts and has the advantages of mild reaction conditions, simple separation, high degradation efficiency, and catalyst recyclability.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A method for catalyzing the degradation of polyimide using ionic liquids, comprising uniformly mixing an ionic liquid catalyst, polyimide, water and an organic solvent and then performing a hydrolysis reaction;

[0008] The ionic liquid catalyst is a compound of the structure shown in Formula I or Formula II:

[0009]

[0010] In Formula I and Formula II, R 1 is an alkyl group, a nitrile alkyl group, a hydroxyalkyl group, an ester group or an ether group; R 2 is a nitrile alkyl group, a hydroxyalkyl group, an ester group, an ether group or an alkyl group, R 3 C 1- C 3Alkyl; Y – Cl – Br – ,OAc – , CH 3 CH 2 COO – CF 3 COO – or (CF 3 SO 2 ) 2 N – .

[0011] In some embodiments of the present invention, the ionic liquid catalyst is aminoethyl triethyl ammonium bromide, hydroxyethyl triethyl ammonium acetate, ethoxy oxo triethyl ammonium trifluoroacetate, methoxy triethyl ammonium propionate, 1-hydroxyethyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide salt, 1-nitromethyl-3-methylimidazolium trifluoroacetate, 1-aminoethyl-3-methylimidazolium bromide or 1-hydroxyethyl-3-imidazole acetate. The structural formula is shown in Formula IL-1 to Formula IL-8:

[0012]

[0013] Different ionic liquids have different effects on the reaction yield. When the cation is ether-substituted ammonium cation and the anion is trifluoroacetate ion (IL-3), the ionic liquid has the best degradation effect on polyimide.

[0014] In some embodiments of the present invention, the molar ratio of the ionic liquid catalyst to the polyimide unit is (0.05-5):1.

[0015] In some embodiments of the present invention, the molar ratio of the ionic liquid catalyst to the polyimide unit is (0.1-0.5):1.

[0016] In some embodiments of the present invention, the molar ratio of the ionic liquid catalyst to the polyimide unit is 0.2:1.

[0017] In some embodiments of the present invention, the organic solvent is N,N-dimethylformamide; the molar ratio of the ionic liquid catalyst to the N,N-dimethylformamide is 1:(5.0-15.0).

[0018] In some embodiments of the present invention, the molar ratio of the ionic liquid catalyst to the N,N-dimethylformamide is 1:(5.0-10.0).

[0019] In some embodiments of the present invention, the molar ratio of the ionic liquid catalyst to the N,N-dimethylformamide is 1:(8.0-10.0).

[0020] In some embodiments of the present invention, the molar ratio of the ionic liquid catalyst to the N,N-dimethylformamide is 1:8.

[0021] In some embodiments of the present invention, the molar ratio of the ionic liquid catalyst to water is 1:(5-50.0).

[0022] In some embodiments of the present invention, the molar ratio of the ionic liquid catalyst to water is 1:(10.0-20.0).

[0023] In some embodiments of the present invention, the molar ratio of the ionic liquid catalyst to water is 1:(10.0-16.0).

[0024] In some embodiments of the present invention, the molar ratio of the ionic liquid catalyst to water is 1:10.

[0025] In some embodiments of the present invention, the hydrolysis reaction is carried out at a temperature of 60 to 140° C. and for a time of 8 to 18 hours.

[0026] In some embodiments of the present invention, the hydrolysis reaction is carried out at a temperature of 80 to 130° C. and for a time of 12 to 18 hours.

[0027] In some embodiments of the present invention, the hydrolysis reaction temperature is 100-120° C. and the time is 12-16 hours.

[0028] In some embodiments of the present invention, the hydrolysis reaction temperature is 100° C. and the time is 12 h.

[0029] In some embodiments of the present invention, after the hydrolysis reaction is completed, the reaction solution is cooled to room temperature, and then an extractant is added to the reaction solution for extraction. After extraction, the upper organic phase is collected, and then concentrated and purified to obtain diamine and dianhydride monomers; the lower aqueous phase is collected, and then the aqueous phase is evaporated to obtain an ionic liquid, which can be recycled.

[0030] In some embodiments of the present invention, the extractant is n-hexane, diethyl ether, dibutyl ether, methyl acetate or ethyl acetate.

[0031] The present invention discloses the following technical effects:

[0032] The present invention uses ionic liquid as a catalyst, has the advantages of mild reaction conditions (such as 100° C.), simple separation, etc., can efficiently catalyze the hydrolysis reaction of waste polyimide, and has broad industrial application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0034] Figure 1 This is a schematic diagram of the process of catalyzing the degradation of polyimide by ionic liquid of the present invention. DETAILED DESCRIPTION

[0035] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0036] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0037] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0038] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to the skilled artisan. The present invention description and examples are exemplary only.

[0039] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0040] according to Figure 1 The flow chart shown in the figure is used to carry out the hydrolysis reaction of polyimide, and the specific steps are as follows:

[0041] Before the reaction, polyimide powder, N,N-dimethylformamide, water and ionic liquid catalyst are added to the reactor in sequence. Under stirring and heating conditions, the reaction liquid becomes homogeneous. After the reaction is completed, it is left to cool to room temperature. An extractant is added to the reaction liquid, and the product and the catalyst are separated into layers. The upper layer is dianhydride and diamine monomers, and the lower layer is ionic liquid. Subsequently, the upper layer of liquid is poured into a round-bottom flask, concentrated, and passed through a column to obtain the target product. After the lower layer is simply heated and dried, it can be recycled into the reaction.

[0042] The technical solutions described in the present invention, unless otherwise specified, are all conventional solutions in the art, and the reagents or raw materials used, unless otherwise specified, are purchased from commercial channels or have been disclosed.

[0043] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with the embodiments, but the content of the present invention is not limited to the following embodiments.

[0044] Examples 1 to 8

[0045] Polyimide (PI, 2.5mmol monomer), water (5.0mmol), N,N-dimethylformamide (6.0mmol) and different ionic liquids (0.5mmol) were added into a 25mL reaction kettle, moved into an oil bath set at 100°C, and stirred and heated for 12 hours; after the reaction was terminated, it was cooled to room temperature; then, 5mL of ethyl acetate was added to the reaction solution, and extraction was performed three times; the upper organic phase was taken, concentrated, and column-filtered to obtain p-phenylenediamine and bisphenol A type diether tetracarboxylic acid; the lower ionic liquid was dried in a vacuum drying oven at 80°C for 12 hours and then directly put into the next use.

[0046]

[0047] Table 1 Reaction conditions and reaction results of Examples 1 to 8

[0048]

[0049]

[0050] Examples 9 to 13

[0051] The ionic liquid IL-3 of Example 3 with the best effect was used as the catalyst, and the other reaction conditions were the same as those of Example 2. The catalyst performance was studied at different temperatures, and the results are listed in Table 2.

[0052] Table 2 Reaction conditions and reaction results of Examples 9 to 13

[0053] Example Reaction temperature (℃) BA yield (%) 9 60 22 10 80 40 11 100 89 12 110 91 13 120 92

[0054] Embodiments 14 to 16

[0055] The ionic liquid IL-3 of Example 3 was used as a catalyst, the reaction was carried out at 100° C., and the other reaction conditions were the same as those of Example 3. The effect of different ionic liquid / water molar ratios on the product yield was investigated. The results are listed in Table 3.

[0056] Table 3 Reaction conditions and reaction results of Examples 14 to 16

[0057] Example Ionic liquid / water BA yield (%) 14 1 / 5 68 15 1 / 10 89 16 1 / 15 91

[0058] Embodiments 17 to 19

[0059] The ionic liquid IL-3 of Example 3 was used as a catalyst, and the reaction was carried out at 100° C. and an ionic liquid / water molar ratio of 1 / 10. Other reaction conditions were the same as those in Example 3. The effect of different reaction times on the product yield was investigated. The results are listed in Table 4.

[0060] Table 4 Reaction conditions and reaction results of Examples 17 to 19

[0061] Example Reaction time (h) Yield (%) 17 8 65 18 12 89 19 16 90

[0062] Embodiments 20 to 25

[0063] Catalyst recycling: The dried ionic liquid recovered in Example 3 was used as a catalyst to study the catalyst recycling performance at 100°C, 12 hours and an ionic liquid / water molar ratio of 1 / 10. The results are listed in Table 6.

[0064] Table 6 Reaction conditions and reaction results of Examples 20 to 25

[0065] Example Repetitions Yield (%) 20 0 89 21 1 92 22 2 90 23 3 91 24 4 88 25 5 86

[0066] 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 principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for catalyzing the degradation of polyimide using ionic liquids, characterized in that: The ionic liquid catalyst, polyimide, water and organic solvent are uniformly mixed and then subjected to a hydrolysis reaction; The ionic liquid catalyst is a compound of the structure shown in Formula I or Formula II: In Formula I and Formula II, R 1 is an alkyl group, a nitrile alkyl group, a hydroxyalkyl group, an ester group or an ether group; R2 is a nitrile alkyl group, a hydroxyalkyl group, an ester group, an ether group or an alkyl group, and R3 is C 1- C3 alkyl; Y – Cl – Br – ,OAc – 、CH3CH2COO – CF3COO – or (CF3SO2)2N – .

2. The method for catalyzing the degradation of polyimide using ionic liquid according to claim 1, characterized in that: The ionic liquid catalyst is aminoethyl triethyl ammonium bromide, hydroxyethyl triethyl ammonium acetate, ethoxy oxo triethyl ammonium trifluoroacetate, methoxy triethyl ammonium propionate, 1-hydroxyethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-nitrile methyl-3-methylimidazolium trifluoroacetate, 1-aminoethyl-3-methylimidazolium bromide or 1-hydroxyethyl-3-imidazole acetate.

3. The method for catalyzing the degradation of polyimide using ionic liquid according to claim 1, characterized in that: The molar ratio of the ionic liquid catalyst to the polyimide unit is (0.05-5):

1.

4. The method for catalyzing the degradation of polyimide using ionic liquid according to claim 1, characterized in that: The organic solvent is N,N-dimethylformamide; the molar ratio of the ionic liquid catalyst to the N,N-dimethylformamide is 1:(5.0-15.0).

5. The method for catalyzing the degradation of polyimide using ionic liquid according to claim 1, characterized in that: The molar ratio of the ionic liquid catalyst to water is 1:(5-50.0).

6. The method for catalyzing the degradation of polyimide using ionic liquid according to claim 1, characterized in that: The temperature of the hydrolysis reaction is 60-140° C. and the time is 8-18 hours.

7. The method for catalyzing the degradation of polyimide using ionic liquid according to claim 1, characterized in that: After the hydrolysis reaction is completed, the step of cooling the reaction solution to room temperature and then adding an extractant to the reaction solution for extraction is also included.

8. The method for catalyzing the degradation of polyimide using ionic liquids according to claim 7, characterized in that: The extractant is n-hexane, ethyl ether, butyl ether, methyl acetate or ethyl acetate.

Images