Chemical upgrading recovery method of polystyrene plastic

Abstract

The invention discloses a chemical upgrading recovery method of polystyrene plastics. The method is based on Friedel-Crafts reaction (Friedel-Crafts Reaction), and a class of multicolor polymer fluorescent materials with conventional luminescence property and aggregation-induced emission (AIE) property are obtained. Polymer materials with different fluorescence colors can be obtained by regulating and controlling the reaction ratio and reaction temperature of the polystyrene plastic and the catalyst, and the adjustable emission wavelength is realized. The chemical upgrading recovery method of the polystyrene plastic has the characteristics of wide raw material source, simple operation process, low cost, easiness in large-scale production, stable property and the like. The obtained multicolor fluorescent polymer material has strong fluorescence and high quantum yield in a solid powder state or a solution state, and has better application prospects in the fields of plastic recovery, plastic modification, plastic processing, biomedical treatment, fluorescent labeling, organic photoelectricity, chemical sensing and the like.

Description

Technical Field

[0001] The invention relates to the technical field of polymer recycling, and in particular to a method for chemically upgrading and recycling polystyrene plastics based on Friedel-Crafts reaction. Background Art

[0002] The production and use of plastic products have greatly promoted the development of social economy and have become an indispensable part of our daily life. Polystyrene plastics are widely used in food containers, tableware and building sound insulation materials due to their excellent performance. However, while plastics bring great convenience to people's lives, the waste plastic pollution caused by them is also one of the environmental problems that need to be solved urgently. Plastics themselves are not pollutants. The rational recycling and reuse of waste plastics is not only an urgent need to reduce the burden on the environment, but also an inevitable choice for achieving sustainable economic development. Chemical upgrading and recycling of waste plastics refers to the conversion of plastic waste into molecular intermediates or high-value-added products through chemical means to achieve the upgrading and recycling of waste plastics. Converting waste polystyrene plastics into high-value-added products helps solve the pollution problem of waste plastics.

[0003] Friedel-Crafts reaction is a Lewis acid-catalyzed electrophilic substitution reaction of halogen on aromatic rings. Based on the Friedel-Crafts reaction, the present invention develops a synthesis method for chemically upgrading polystyrene plastics into multicolor fluorescent polymers. Summary of the invention

[0004] Polystyrene plastics have a short service life during daily use, resulting in huge waste of resources and environmental pollution. In order to solve the problems of high cost and complicated procedures of existing methods for recycling waste polystyrene plastics, the purpose of the present invention is to provide a method for chemically upgrading and recycling waste polystyrene plastics to prepare polymer materials with excellent optical properties, which has simple operation, mild conditions and low modification cost.

[0005] The objective of the present invention is achieved by providing a chemical upgrading and recycling method for polystyrene plastics, characterized in that, based on the Friedel-Crafts reaction mechanism, waste or new polystyrene plastics are used as raw materials, and a multicolor fluorescent polymer is obtained in one step by controlling the reaction ratio and reaction temperature under the action of a Friedel-Crafts reaction catalyst.

[0006] Furthermore, the chemical structure of the multicolor fluorescent polymer contains a polystyrene-like structure, which has conventional luminescence properties and aggregation-induced luminescence properties, and can achieve multicolor luminescence from blue light to yellow light in the solid state and in the solution state of the polymer by regulating the reaction conditions.

[0007] Furthermore, the chemical upgrading and recycling method of polystyrene plastics is characterized in that the specific steps are: adding the dried polystyrene plastics, organic solvents, and Friedel-Crafts reaction catalysts into a reactor equipped with a magnetic stirrer, reacting at a certain temperature and nitrogen atmosphere, and performing post-treatment after a period of reaction time to obtain a multicolor fluorescent polymer.

[0008] Furthermore, the chemical upgrading and recycling method of a polystyrene plastic is characterized in that the polystyrene plastic refers to a plastic containing polystyrene units, including polystyrene (PS), styrene-butadiene rubber (SBR), acrylonitrile-butadiene-styrene copolymer (ABS) or styrene-maleic anhydride copolymer (SMA), and its structural formula is:

[0009]

[0010] Furthermore, the Friedel-Crafts reaction catalyst is anhydrous aluminum trichloride, anhydrous tin tetrachloride or anhydrous titanium tetrachloride, and the structural formula is:

[0011]

[0012] Furthermore, the organic solvent is a pure solvent or a mixed solvent of a chlorine-containing compound, selected from dichloromethane, chloroform or carbon tetrachloride, and has the structural formula:

[0013]

[0014] Furthermore, the molar ratio of the polystyrene plastic, the catalyst and the organic solvent is 1:(0.01-1):(10-100), and the reaction temperature ranges from 0°C to the boiling point of the organic solvent.

[0015] Furthermore, the post-treatment after a period of reaction time refers to adding excess deionized water to the reaction solution after the reaction is completed to quench the reaction, extracting the organic phase with dichloromethane and washing it with deionized water, taking an appropriate amount of anhydrous magnesium sulfate to dry the organic phase, filtering and collecting the organic phase, concentrating it to obtain a crude product, dropping it into a poor solvent methanol, and obtaining a multicolor fluorescent polymer by a precipitation method.

[0016] Furthermore, the chemical upgrading and recycling method of polystyrene plastics is characterized in that methanol is selected as the poor solvent in the precipitation method, and the volume ratio of the good solvent to the poor solvent is 1:(20-30).

[0017] Furthermore, the obtained multicolor fluorescent polymer is blended with various virgin plastic media as a fluorescent dye and further processed to obtain fluorescent products for use as fabric markings.

[0018] Specifically, the technical method steps provided by the present invention are as follows:

[0019] Step 1: Under the condition of dehydration and deoxygenation, add the dried polystyrene plastic, catalyst and organic solvent into a reaction tube equipped with a magnetic stirrer, carry out modification reaction at a certain temperature, add excess deionized water to the reaction solution after a period of time to quench the reaction, extract the organic phase with dichloromethane and wash it three times with excess water, take an appropriate amount of anhydrous magnesium sulfate to dry the organic phase, filter and collect the organic phase and concentrate to obtain a crude product. The crude product is dripped into a poor solvent drop by drop to obtain a polymer material by precipitation method.

[0020] Among them, the structural formula of polystyrene plastics is:

[0021]

[0022] Wherein, the catalyst structural formula is:

[0023]

[0024] Among them, the organic solvent structural formula is:

[0025]

[0026] Optionally, the method for removing water and oxygen is to use a vacuum pump to remove the air in the reaction tube, purge with nitrogen for 10 minutes, and finally introduce nitrogen.

[0027] Optionally, the organic solvent is a pure solvent or a mixed solvent of chlorine-containing compounds such as dichloromethane, chloroform, carbon tetrachloride, etc.

[0028] Optionally, the molar ratio of the polystyrene plastic, the catalyst and the organic solvent is 1:(0.01-1):(10-100).

[0029] Optionally, the reaction temperature is from 0°C to the boiling point of the solvent.

[0030] Optionally, concentration to obtain a crude product is performed using a rotary evaporator.

[0031] Alternatively, the anhydrous magnesium sulfate used to dry the organic phase may be replaced with other inorganic water-absorbing desiccants (such as anhydrous sodium sulfate, etc.).

[0032] Furthermore, the novel material generated by the chemical upgrading and recycling method of polystyrene plastics described in the present invention has luminescent properties, and its fluorescence changes with the change of the reaction molar ratio of polystyrene plastics and catalysts, and exhibits fluorescence of different colors from dark blue to yellow under irradiation with a 365nm lamp. Most polymer materials in the solid state have fluorescence emission in the range of 419 to 573nm when excited at the maximum excitation wavelength in the range of 300 to 400nm; the fluorescence in the solution state is concentration-dependent, and is mostly emitted in the range of 415 to 487nm.

[0033] In order to improve the reaction efficiency, the preparation method of the present invention preferably further includes: before the modification reaction, dehydrating and deoxygenating the reaction system. The present invention has no particular limitation on the dehydrating and deoxygenating method, which can be a conventional dehydrating and deoxygenating method in the art, such as vacuum drying, replacement with inert gas, and the like.

[0034] Based on the Friedel-Crafts reaction, the present invention discovered the multicolor fluorescence characteristics of the product by regulating the reaction conditions of polystyrene plastic modification, and obtained a series of multicolor polymer fluorescent materials with high quantum yield by connecting the alkyl in the chlorine-containing compound to the aromatic group of the polystyrene side chain. The present invention is a new strategy for chemical upgrading and recycling of waste polystyrene plastic modified to prepare fluorescent polymer materials.

[0035] The present invention has the following beneficial effects:

[0036] 1. The Friedel-Crafts reaction-based chemical upgrading and recycling method for polystyrene plastics disclosed in the present invention has the advantages of mild reaction conditions, simple steps, convenient operation, low cost, etc.

[0037] 2. The new material provided by the present invention has luminescent properties, and the fluorescent color can be controlled by adjusting the molar ratio of the reaction raw material polystyrene plastic and the catalyst reaction and the reaction temperature. The change from blue light to yellow light can be achieved in the solid state, and the change from blue light to cyan light can be achieved in the solution state. At the same time, the new fluorescent material provided by the present invention has a high quantum yield in both the solid state and the solution state.

[0038] 3. The chemical upgrading method of polystyrene plastics provided by the present invention upgrades waste polystyrene plastics with low recycling rate into high value-added chemicals, which helps to solve the environmental pollution problem of plastics.

[0039] 4. The multicolor fluorescent polymer provided by the present invention can be applied to the preparation of fluorescent labeling, patterning, display and optoelectronic components such as LED and OLED due to its high quantum yield in the aggregated state. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The specific implementation modes of the present invention are further described in detail below with reference to the accompanying drawings.

[0041] Figure 1 is the hydrogen nuclear magnetic resonance spectrum of the polymer in Example 1.

[0042] Figure 2 This is the cyan fluorescence curve of the luminescent polymer obtained by modifying waste polystyrene plastic foam catalyzed by anhydrous aluminum chloride in Example 2.

[0043] Figure 3This is the quantum yield spectrum of the blue fluorescent polymer obtained by modifying waste polystyrene plastic foam catalyzed by anhydrous aluminum chloride in Example 1.

[0044] Figure 4 The fluorescence spectrum curves of fluorescent materials of different colors obtained by controlling the modification reaction of the reaction raw material waste polystyrene plastic foam with different equivalent catalyst anhydrous aluminum chloride in Example 1.

[0045] Figure 5 This is an electronic photograph of a fluorescent film product obtained by blending the multicolor fluorescent polymer prepared in Example 1 with virgin polymethyl methacrylate pellets in Example 3. DETAILED DESCRIPTION

[0046] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. The following specific implementation methods are only used to explain the present invention, and the protection scope is not limited by the following embodiments.

[0047] The experimental data in the examples were measured using the following instruments and measurement methods:

[0048] (1) Method for determining the chemical structure of the generated polymer: using nuclear magnetic resonance spectroscopy;

[0049] (2) Method for determining the fluorescence properties of the generated polymer: using a fluorescence spectrometer.

[0050] Embodiment 1:

[0051] This embodiment provides a method for preparing a fluorescent polymer by modifying waste polystyrene plastic foam catalyzed by anhydrous aluminum chloride.

[0052] The chemical reaction formula of the waste polystyrene plastic foam and dichloromethane used in this example under the catalysis of anhydrous aluminum chloride is shown as follows:

[0053]

[0054] This embodiment includes the following steps:

[0055] (1) The reaction raw material waste polystyrene plastic foam (1 eq, 0.2 g) and the catalyst anhydrous aluminum chloride (0.16 eq, 0.04 g) were placed in a dry reaction tube containing a magnetic stirrer, the air in the reaction tube was removed by a vacuum pump, nitrogen was purged for 10 minutes, and finally nitrogen was introduced;

[0056] (2) Take an organic solvent, dichloromethane (40.6 eq, 5 mL) and add it to the reaction tube of step (1) under a nitrogen atmosphere. Place the reaction tube in an oil bath at 25° C. and stir.

[0057] (3) After reacting for 24 hours, excess deionized water was added to the reaction solution to quench the reaction, and the organic phase was extracted with dichloromethane and washed three times with deionized water. The organic phase was collected and dried with an appropriate amount of anhydrous magnesium sulfate, filtered, collected, and concentrated to obtain a crude product.

[0058] (4) The crude product was added dropwise into methanol at a volume ratio of good solvent (dichloromethane) to poor solvent (methanol) of 1:(20-30), and the product was obtained by precipitation method with a yield of 86%. The product emitted deep blue fluorescence and had AIE properties, and the solid state quantum yield was as high as 47%.

[0059] Embodiment 2:

[0060] This embodiment provides a method for preparing a fluorescent polymer by modifying waste polystyrene plastic foam catalyzed by anhydrous aluminum chloride.

[0061] The chemical reaction formula of the waste polystyrene plastic foam and dichloromethane used in this example under the catalysis of anhydrous aluminum chloride is shown as follows:

[0062]

[0063] This embodiment includes the following steps:

[0064] (1) The reaction raw material waste polystyrene foam (1 eq, 0.2 g) and the catalyst anhydrous aluminum chloride (0.23 eq, 0.06 g) were placed in a dry reaction tube containing a magnetic stirrer, the air in the reaction tube was removed by a vacuum pump, nitrogen was purged for 10 minutes, and finally nitrogen was introduced;

[0065] (2) Take an organic solvent, dichloromethane (24.4 eq, 3 mL) and add it to the reaction tube of step (1) under a nitrogen atmosphere. Place the reaction tube in an oil bath at 25° C. and stir.

[0066] (3) After reacting for 24 hours, excess deionized water was added to the reaction solution to quench the reaction, and the organic phase was extracted with dichloromethane and washed three times with deionized water. The organic phase was collected and dried with an appropriate amount of anhydrous magnesium sulfate, filtered, collected, and concentrated to obtain a crude product.

[0067] (4) The crude product was added dropwise into methanol at a volume ratio of good solvent (dichloromethane) to poor solvent (methanol) of 1:(20-30), and the product was obtained by precipitation method with a yield of 47%. The product emitted cyan fluorescence and had AIE properties, and the solid state quantum yield was 25%.

[0068] Embodiment 3:

[0069] This embodiment provides a method for obtaining a fluorescent film product by blending the multicolor fluorescent polymer prepared in Example 1 with virgin polymethyl methacrylate pellets.

[0070] This embodiment includes the following steps:

[0071] (1) Weigh 30 mg of the multicolor fluorescent polymer prepared in Example 1 and 570 mg of polymethyl methacrylate pellets respectively into a dry sample bottle with a magnetic stirrer, and add 3 mL of tetrahydrofuran;

[0072] (2) Place the sample bottle in a 60°C oil bath and stir for 10 min;

[0073] (3) The uniformly mixed solution was added into a mold, dried in a vacuum drying oven at 40° C. for 10 h, and demolded to obtain a fluorescent film product.

[0074] Finally, it should be noted that the above examples are only some specific embodiments of the present invention. The modified raw materials used in the present invention include but are not limited to waste polystyrene plastic foams, and the modification reactions of plastic products containing polystyrene structures derived from the modification method disclosed in the present invention should be considered as the protection scope of the present invention.

Claims

1. A chemical upgrading and recycling method for polystyrene plastics, characterized in that: Based on the Friedel-Crafts reaction mechanism, waste or new polystyrene plastics are used as raw materials. Under the action of Friedel-Crafts reaction catalyst, multicolor fluorescent polymers are obtained in one step by controlling the reaction ratio and reaction temperature.

2. A method for chemical upgrading of polystyrene plastics according to claim 1, characterized in that: The multicolor fluorescent polymer has a polystyrene structure in its chemical structure, has conventional luminescence properties and aggregation-induced luminescence properties, and can achieve multicolor luminescence from blue light to yellow light in the solid state and in the solution state of the polymer by regulating the reaction conditions.

3. The chemical upgrading and recycling method of polystyrene plastics according to claim 1, characterized in that: The specific steps are: adding dried polystyrene plastics, organic solvents, and Friedel-Crafts reaction catalysts into a reactor equipped with a magnetic stirrer, reacting at a certain temperature and in a nitrogen atmosphere, and performing post-treatment after a period of reaction to obtain a multicolor fluorescent polymer.

4. A chemical upgrading and recycling method for polystyrene plastics according to any one of claims 1 to 3, characterized in that: Polystyrene plastics refer to plastics containing polystyrene units, including polystyrene (PS), styrene-butadiene rubber (SBR), acrylonitrile-butadiene-styrene copolymer (ABS) or styrene-maleic anhydride copolymer (SMA), and its structural formula is: ， 。 5. A chemical upgrading and recycling method for polystyrene plastics according to any one of claims 1 to 3, characterized in that: The Friedel-Crafts reaction catalyst is anhydrous aluminum trichloride, anhydrous tin tetrachloride or anhydrous titanium tetrachloride, and the structural formula is: 。 6. The chemical upgrading and recycling method of polystyrene plastics according to claim 3, characterized in that: The organic solvent is a pure solvent or a mixed solvent of a chlorine-containing compound, selected from dichloromethane, chloroform or carbon tetrachloride, and has the structural formula: 。 7. The chemical upgrading and recycling method of polystyrene plastics according to claim 3, characterized in that: The molar ratio of the polystyrene plastic, the catalyst and the organic solvent is 1:(0.01-1):(10-100), and the reaction temperature range is 0 o C ~ boiling point of organic solvent.

8. The chemical upgrading and recycling method of polystyrene plastics according to claim 3, characterized in that: The post-treatment after a period of reaction time refers to adding excess deionized water to the reaction solution after the reaction is completed to quench the reaction, extracting the organic phase with dichloromethane and washing it with deionized water, taking an appropriate amount of anhydrous magnesium sulfate to dry the organic phase, filtering and collecting the organic phase, concentrating it to obtain a crude product, dropping it into a poor solvent methanol, and obtaining a multicolor fluorescent polymer by a precipitation method.

9. A method for chemical upgrading of polystyrene plastics according to claim 8, characterized in that: Methanol was selected as the poor solvent in the precipitation method, and the volume ratio of the good solvent to the poor solvent was 1:(20~30).

10. A method for chemical upgrading of polystyrene plastics according to any one of claims 1 to 9, characterized in that: The obtained multicolor fluorescent polymer is blended with various virgin plastic media as a fluorescent dye and further processed to obtain fluorescent products for use as fabric markings.

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