Polycarbonate waste plastic amine alcoholysis method using alcohol as solvent

Abstract

The invention belongs to the technical field of plastic recycling, and particularly relates to a polycarbonate and polyester waste plastic ammonolysis method taking alcohol as a solvent. According to the method, an alcohol compound serves as a solvent, an ammonia compound serves as a depolymerization reagent, waste polycarbonate and polyester plastic are depolymerized, a corresponding depolymerization product is obtained through a green and mild way, and therefore effective and green recycling of the waste polyester plastic is achieved. The depolymerization method provided by the invention has the advantages of cheap and easily available reagents, green and mild conditions, simple post-treatment, fast and efficient reaction under mild conditions, and good depolymerization effect.

Description

Technical Field

[0001] This invention belongs to the field of plastic recycling technology, specifically relating to a method for the aminolysis of polycarbonate waste plastics using alcohol as a solvent. Background Technology

[0002] Polycarbonate and polyester plastics are the most widely used synthetic polymers in the world. Polycarbonate, in particular, plays a significant role as an engineering plastic in the construction industry, electrical components, packaging manufacturing, and automotive parts due to its good toughness, impact strength, and resistance to water and some solvents. Polyester plastics, including PET, PLA, and PCL, are highly attractive due to their good thermal and mechanical properties, processing versatility, and biodegradability. PET is the most important and abundant type. It is also widely used as a thermoplastic polymer, possessing excellent properties including thermal stability, transparency, high strength, low density, chemical resistance, and low cost.

[0003] However, in recent decades, the stable and non-degradable chemical properties of plastics have led to a massive accumulation of waste plastics, seriously threatening the sustainable development of the ecological environment. In recent years, plastic recycling technology has attracted considerable attention, but to date, less than 10% of plastic waste is recycled, about 10% is incinerated, and the remaining 80% is sent to landfills or simply dumped into the environment. However, landfilling and incineration cannot solve the problem of unsustainable plastics; they ultimately release greenhouse gases and other substances, causing environmental pollution. Chemical recycling of waste plastics can fully utilize the carbon resources within them, yielding new, high-performance plastics or upgrading them into higher-value chemicals.

[0004] In polycarbonate and polyester plastics, chemical recycling methods include pyrolysis, hydrolysis, ammonolysis, and alcoholysis. Among these, ammonolysis yields monomers and higher-value compounds, making it a promising method for the chemical upgrading and recycling of waste plastics. Although current research has made some progress, most methods use toxic and harmful solvents, leading to cumbersome post-processing steps and various types of pollution. However, ammonolysis of polycarbonate plastics using alcohols as a green solvent has not yet been researched or reported. Summary of the Invention

[0005] To address the aforementioned problems, this invention aims to provide a green amino alcoholysis method for polycarbonate waste plastics using alcohol as a solvent.

[0006] The specific method of this invention is as follows:

[0007] In an air atmosphere at a certain temperature, a certain amount of amino alcohol depolymerization reagent, polyester plastic, and finally alcohol solvent were added to the reactor. The reactor was sealed and stirred to depolymerize polycarbonate and polyester plastic. After the reaction was completed, the unreacted plastic was removed by washing and filtering with ethanol. The weight of the filter paper before and after filtration was measured to obtain the conversion rate. The filtrate was rotary evaporated at 60°C to remove ethanol and alcohol solvent, and bisphenol A and the corresponding depolymerization products were obtained. The results were quantified by nuclear magnetic resonance spectroscopy.

[0008] Further specifying, polycarbonate plastic is PC.

[0009] To further specify, the structural formula of polycarbonate (PC) is:

[0010]

[0011] Among them, R 1 It represents an aliphatic or aromatic group.

[0012] Furthermore, the number average molecular weight of polycarbonate plastics is 10. 2 ~10 7 g / mol,

[0013] Further specifying, the structural formula of the aminohydrolysis reagent is:

[0014]

[0015] In this context, R1, R2, and R3 represent hydrogen, alkyl, aryl, or halogen atoms, and n ≥ 1.

[0016] Furthermore, the carbon number of ammonia compounds is specified as 1 to 50.

[0017] Furthermore, the ammonia compound is one or a mixture of n-butylamine and benzylamine in any proportion, or one or a mixture of ethanolamine, 3-aminopropanol, and 4-amino-1-butanol in any proportion.

[0018] Further, the amount of ammonia reagent used in the reaction is limited to 1–500 molar ratio.

[0019] Further, the reaction temperature is limited to 0–300℃.

[0020] Further specifying, alcohol solvents include one or more of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, n-pentanol, ethylene glycol, glycerol, 1,2-propanediol, and 1,3-propanediol.

[0021] The advantages of this invention are:

[0022] (1) This invention uses a combination of green alcohol solvents as solvents for the depolymerization of amines or amino alcohols, which simplifies the experimental procedure and conforms to the principles of green chemistry.

[0023] (2) The amino alcohol depolymerization reagent used in this invention is a commercial reagent that is cheap and readily available. The depolymerization reaction without metal catalyst can save the post-processing process in the later stage of the reaction. The post-processing is simple, making the production process more green and environmentally friendly.

[0024] (3) The present invention can achieve the depolymerization of polycarbonate and polyester materials under mild conditions, without the need for harsh reaction conditions such as high temperature and high pressure. Attached Figure Description

[0025] Figure 1 The NMR spectrum of the product after complete depolymerization of polycarbonate in Example 1;

[0026] Figure 2 This is a photograph of the transparent solution product obtained after complete depolymerization of polycarbonate in Example 1. Detailed Implementation

[0027] In an air atmosphere at a certain temperature, amines or amino alcohol depolymerization reagents are added to the reactor, followed by polycarbonate plastic, and finally an alcohol solvent is added. The reactor is then sealed to allow the polycarbonate plastic to depolymerize.

[0028] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the materials, reagents, methods, and instruments used are all conventional materials, reagents, methods, and instruments in the art, and can be obtained commercially by those skilled in the art.

[0029] Example 1:

[0030]

[0031] The experimental procedure includes the following steps:

[0032] The reaction was carried out at 50 °C and 500 rpm. Ethanolamine (122 μl, 2 mmol) was added to the reaction flask, followed by PC (254 mg, 1 mmol based on the number of carbonyl groups), and finally 1 mL of methanol as solvent. After magnetic stirring until homogeneous, timing was started. Quantitative analysis was performed using NMR after 2 h 07 min. The yield of the 1,3-oxazine-2-one five-membered ring product was 96%, and the yield of BPA was 96%.

[0033] Example 2:

[0034] The depolymerization of polycarbonate proceeds as follows:

[0035]

[0036] The experimental procedure includes the following steps:

[0037] The reaction was carried out at 50 °C and 500 rpm. Ethanolamine (122 μl, 2 mmol) was added to the reaction flask, followed by PC (254 mg, 1 mmol based on the number of carbonyl groups), and finally 1 mL of ethanol as solvent. After magnetic stirring until homogeneous, timing was started. Quantitative analysis was performed using NMR after 2 h 35 min. The yield of the 1,3-oxazine-2-one five-membered ring product was 99%, and the yield of BPA was 99%.

[0038] Example 3:

[0039]

[0040] The experimental procedure includes the following steps:

[0041] The reaction was carried out at 50 °C and 500 rpm. Ethanolamine (122 μl, 2 mmol) was added to the reaction flask, followed by PC (254 mg, 1 mmol based on the number of carbonyl groups), and finally 1 mL of n-propanol as the solvent. After magnetic stirring until homogeneous, timing was started. Quantitative analysis was performed using NMR after 2 h 54 min. The yield of the 1,3-oxazine-2-one five-membered ring product was 92%, and the yield of BPA was 92%.

[0042] Example 4:

[0043]

[0044] The experimental procedure includes the following steps:

[0045] The reaction was carried out at 50 °C and 500 rpm. Ethanolamine (122 μl, 2 mmol) was added to the reaction flask, followed by PC (254 mg, 1 mmol based on the number of carbonyl groups), and finally 1 mL of n-butanol as the solvent. After magnetic stirring until homogeneous, timing was started. Quantitative analysis was performed using NMR after 3 h 0 6 min. The yield of the 1,3-oxazine-2-one five-membered ring product was 95%, and the yield of BPA was 93%.

[0046] Example 5:

[0047]

[0048] The experimental procedure includes the following steps:

[0049] The reaction was carried out at 50 °C and 500 rpm. Ethanolamine (122 μl, 2 mmol) was added to the reaction flask, followed by PC (254 mg, 1 mmol based on the number of carbonyl groups), and finally 1 mL of isopropanol as the solvent. After magnetic stirring until homogeneous, timing was started. Quantitative analysis was performed using NMR after 4 h 54 min. The yield of the 1,3-oxazine-2-one five-membered ring product was 99%, and the yield of BPA was 99%.

[0050] Example 6:

[0051]

[0052] The experimental procedure includes the following steps:

[0053] The reaction was carried out at 50 °C and 500 rpm. Ethanolamine (122 μl, 2 mmol) was added to the reaction flask, followed by PC (254 mg, 1 mmol based on the number of carbonyl groups), and finally 1 mL of tert-butanol as the solvent. After magnetic stirring until homogeneous, timing was started. After 9 h 42 min of reaction, quantification was performed using NMR. The yield of the 1,3-oxazine-2-one five-membered ring product was 96%, and the yield of BPA was 94%.

[0054] Example 7:

[0055]

[0056] The experimental procedure includes the following steps:

[0057] The reaction was carried out at 50 °C and 500 rpm. Ethanolamine (122 μl, 1 mmol) was added to the reaction flask, followed by PC (254 mg, 1 mmol based on the number of carbonyl groups), and finally 111.4 μl of ethylene glycol, 244 μl of ethyl acetate, and 444 μl of methanol as solvents. The mixture was magnetically stirred until homogeneous, and timing was started. After 1 h of reaction, NMR quantification showed that the yield of the 1,3-oxazine-2-one five-membered ring product was 83%, and the yield of BPA was 82%.

[0058] Example 8:

[0059]

[0060] The experimental procedure includes the following steps:

[0061] The reaction was carried out at 50 °C and 500 rpm. 3-Aminopropanol (153 μL, 2 mmol) was added to the reaction flask, followed by PC (254 mg, 1 mmol based on the number of carbonyl groups), and finally 1 mL of ethanol as solvent. After magnetic stirring and timing, the conversion reached 91% after 4 h 28 min. Quantitative analysis using NMR showed that the yield of the 1,3-oxazine-2-one six-membered ring product was 34.2%, and the yield of BPA was 90%. The byproduct was… Yield: 56.8%.

Claims

1. A method for the aminohydrolysis of polycarbonate waste plastics using alcohol as a solvent, characterized in that, The method is as follows: In an air atmosphere at a certain temperature, an ammonia-based depolymerization agent, polycarbonate or polyester plastic is added to the reactor, followed by the addition of an alcohol solvent. The reactor is then sealed to depolymerize the polyester plastic, yielding bisphenol A and the corresponding depolymerization products, thus achieving the degradation of the polyester plastic.

2. The method for aminolysis and amino-alcoholic hydrolysis of polyester waste plastics using alcohol as a solvent according to claim 1, characterized in that, The polyester structure is as follows: Where R 1 It represents an aliphatic or aromatic group.

3. The method for aminolysis and amino alcoholysis of polycarbonate waste plastics using alcohol as a solvent according to claim 2, characterized in that, The polycarbonate plastic has a number-average molecular weight of 10. 2 ~10 7 g / mol.

4. The method for aminolysis of polyester waste plastics using alcohol as a solvent according to claim 1, characterized in that, The structural formula of the aforementioned amino alcohol compounds is: Where R1 and R2 represent hydrogen, alkyl, aryl, or halogen atoms, and n≥1.

5. A method for ammonolysis of polycarbonate waste plastics using alcohol as a solvent, as described in claim 1 or 4, characterized in that... The amines and alcohols mentioned herein contain 1 to 50 carbon atoms.

6. The method for aminolysis and amino alcoholysis of polyester waste plastics using alcohol as a solvent according to claim 5, characterized in that... The amine compounds are one or a mixture of n-butylamine and benzylamine in any proportion, and the alcohol compounds are one or a mixture of more than one of ethanolamine, 3-aminopropanol, and 4-amino-1-butanol in any proportion.

7. The method for aminolysis and amino alcoholysis of polyester waste plastics using alcohol as a solvent according to claim 1, characterized in that... The amount of amines and amino alcohols added is 1 to 500 equivalents of the polyester plastic (based on the number of carbonyl groups in the polyester).

8. The method for aminolysis and amino alcoholysis of polyester waste plastics using alcohol as a solvent according to claim 1, characterized in that... The reaction temperature is 0–300°C.

9. The method for aminolysis and amino alcoholysis of polyester waste plastics using alcohol as a solvent according to claim 1, characterized in that... The alcohol solvents include one or more of methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, n-pentanol, ethylene glycol, glycerol, 1,2-propanediol, and 1,3-propanediol.

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