Long afterglow material based on waste PET as well as preparation method and application of long afterglow material

Abstract

The invention discloses a long-afterglow material based on waste PET and a preparation method and application thereof.Organic luminescent substance crown alkene serves as luminescent molecules and is fused and doped into recycled waste PET, the waste PET is upgraded and reconstructed into a persistent luminescent polymer element, PET macromolecular chains are folded front and back to form regular lamellas, and the lamellas are uniformly distributed on the surface of the waste PET, so that the long-afterglow material based on the waste PET is obtained. Excitons are stabilized, and oxygen in the atmosphere is prevented from being quenched. Due to the planar and rigid structure of the polycyclic aromatic hydrocarbon, intramolecular movement can be inhibited, so that non-radiative decay channels are reduced, and the ultra-long afterglow effect is realized. According to the long-afterglow material, pollution of waste materials is reduced, upgrading and recycling of resources are achieved, upgrading and recycling steps are simple and convenient, cost is low, the preparation process is easy to scale, economical and efficient, and the long-afterglow material has good industrial popularization prospects and has important application value in the technical field of plastic upgrading and recycling.

Description

Technical Field

[0001] This invention belongs to the field of recycling of waste PET and preparation of long afterglow materials, specifically involving a long afterglow material based on waste PET, its preparation method and application. Background Technology

[0002] Polyethylene terephthalate (PET) is widely used in packaging, textiles, electronics, and optics due to its excellent tensile and impact strength, transparency, processability, chemical resistance, and thermal stability. However, 95% of PET becomes waste within one year of production, and less than 30% of waste PET can be recycled. The ever-accumulating PET waste poses serious environmental and health risks in daily life because the resulting microplastics enter the ecosystem in which humans live.

[0003] "Upgrading and remanufacturing" is commonly used in the recycling process of recycled materials. It effectively improves the performance and value of materials through physical and chemical methods while avoiding energy consumption and reducing the global carbon footprint. It is also playing a vital role in recycled polymers, especially in converting waste PET into high-value-added ultra-long organic phosphorescent (UOP) materials, which opens up a feasible way for upgrading and recycling PET waste into high-performance functional materials.

[0004] To date, various PET recycling strategies have been widely reported, including mechanical recycling, chemical degradation, bio-enzyme catalysis, and chemical modification. For example, Chinese invention patent CN102942783A discloses a composite material of nylon 6 and recycled PET bottles, which reprocesses waste PET into a composite material and applies it to the manufacture of mechanical parts. Another example is Chinese invention patent CN117069417A, which discloses a method for preparing anchoring agents from recycled PET-type unsaturated polyester resin, applying waste PET to the processing and manufacturing of resin anchor rods, thus meeting the application requirements of anchoring agents.

[0005] Furthermore, it is worth noting that traditional polyester materials are being developed into optically functional, persistent light-emitting devices. PET, due to its excellent processability and practicality, can be applied to optical materials. For example, invention patents CN 107325498A and CN109705843B both disclose the preparation of light-emitting materials by combining PET substrates with metal complexes, and have achieved good applications. In addition, the team led by Liang Guodong at Sun Yat-sen University also disclosed a simple molecular doping strategy, using carbazole derivatives as chromophore dopants and electron donors, and melt-blending them with PET to prepare afterglow polymer films with a duration of up to one hour. These films exhibit good flexibility and transparency and are easy to prepare, paving the way for the practical application of afterglow materials in the engineering field (Chinese invention patent 202411904176.X). Although these materials exhibit persistent light-emitting properties and have various application potentials, the economic and environmental benefits of their large-scale application are hindered because the PET substrates used are all in their original state, and waste PET is not used to prepare ultra-long organic phosphorescent polymer materials.

[0006] In recent years, polymer-based ultralong organic phosphorescent materials have shown potential applications in anti-counterfeiting and information encryption, sensing and optoelectronic devices, and bioimaging. Ultralong organic phosphorescent materials can be achieved by promoting intersystem crossover from the lowest excited state to the triplet state while suppressing the nonradiative decay of triplet excitons. Furthermore, improving the afterglow performance of organic phosphors hinges on suppressing their molecular motion and eliminating the quenching effect of oxygen in the air on their triplet excitons. Polycyclic aromatic hydrocarbons (PAHs) are a typical class of organic phosphors; their planar and rigid chemical structures are beneficial for suppressing intramolecular motion, thereby reducing nonradiative decay channels and readily emitting significant fluorescence. To date, several organic compound-based afterglow materials have been reported, such as Chinese invention patent CN116903986A, which discloses a rubber-plastic two-phase organic long afterglow polymer, its preparation method, and its applications. Organic room-temperature phosphorescent tough materials and thermoplastic elastomers were prepared by directly introducing a small amount of polycyclic aromatic hydrocarbons (PAHs) during the polymerization process, and by using monomer dissolution and mechanical stirring to uniformly disperse the dopant in the formed polymer matrix. These materials are used for material damage detection and wearable electronic devices, respectively. Invention patent CN118063915B also discloses an ultralong afterglow polymer doped with small organic molecules, its preparation method, and its applications. By selecting small organic molecules with specific structures and doping them into polymers, ultralong afterglow polymers were obtained. Although embedding PAHs into polymers has resulted in some phosphorescent materials with ultralong lifetimes and different maximum delayed emission values, most of them still have relatively low organic afterglow quantum yields, which cannot meet the needs of large-scale practical applications.

[0007] Therefore, developing long-afterglow polymers with high organic afterglow quantum yield and strong sustained luminescence capability, especially utilizing recyclable PET (R-PET) long-afterglow systems to meet practical application needs, remains a challenge. Summary of the Invention

[0008] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0009] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0010] Therefore, the purpose of this invention is to overcome the shortcomings of the prior art and provide a long afterglow material based on waste PET.

[0011] To solve the above-mentioned technical problems, the present invention provides the following technical solution: the long afterglow material is obtained by blending waste PET with the structure shown in Formula I and crownene, an organic light-emitting substance with the structure shown in Formula II;

[0012]

[0013] In Formula I, the value of n ranges from 50 to 200, and the doping amount of the organic luminescent material crownene relative to waste PET is 0.01 to 2 wt%.

[0014] Another objective of this invention is to provide a method for preparing a long afterglow material based on waste PET.

[0015] To solve the above-mentioned technical problems, the present invention provides the following technical solution: including,

[0016] Waste PET is crushed, washed, and dried to obtain R-PET;

[0017] R-PET and crownene are added to a mixer and blended to obtain a blend R-PET@COR with a crownene doping amount of 0.01 to 2 wt% relative to R-PET.

[0018] R-PET@COR can be further processed to obtain long afterglow luminescent materials in different forms.

[0019] As a preferred embodiment of the preparation method of the long afterglow material based on waste PET according to the present invention, the blending process includes a melt temperature of 250-300°C, a rotation speed of 10-60 r / min, and a blending time of 1-20 min.

[0020] As a preferred embodiment of the preparation method of long afterglow material based on waste PET according to the present invention, the post-processing includes processing by one of a flat vulcanizing machine, a twin-screw extruder, and a cotton candy machine to obtain film-like, filament-like, and fiber-like luminescent materials, respectively.

[0021] As a preferred embodiment of the preparation method of long afterglow material based on waste PET according to the present invention, the processing by the flat vulcanizing machine is as follows: the temperature of the upper and lower plates of the flat vulcanizing machine is 250-300℃, the pre-compression pressure is 0-12MPa, the pre-compression time is 0-60s, the pressurization pressure is 0-14MPa, and the pressurization time is 0-60s.

[0022] As a preferred embodiment of the method for preparing long afterglow material based on waste PET according to the present invention, the processing is carried out by a twin-screw extruder, wherein the temperature of the twin-screw extruder is 250-300°C.

[0023] As a preferred embodiment of the method for preparing long afterglow material based on waste PET according to the present invention, the output temperature of the cotton candy machine is 260℃~280℃ and the centrifugal speed is 2200~2600rpm.

[0024] Another objective of this invention is to provide a method for preparing long-afterglow materials based on waste PET, and to apply the long-afterglow luminescent materials prepared by this method to the preparation of information encryption and anti-counterfeiting materials, packaging materials, and textiles and clothing.

[0025] Beneficial effects of this invention:

[0026] This invention directly utilizes waste PET and organic light-emitting materials to obtain R-PET-based long afterglow materials in a mixer. The afterglow effect of the material can be varied by changing the type and content of organic light-emitting materials in R-PET. Films, filaments and fibers made through different processing modes have excellent mechanical properties, high quantum yield and long afterglow life.

[0027] This invention reduces waste pollution and achieves resource upgrading and reuse by upgrading and remanufacturing waste PET. The upgrading and recycling process is simple and convenient, with low cost, easy to scale up, economical and efficient, and has good prospects for industrial promotion. It has important application value in the field of plastic upgrading and recycling technology. Attached Figure Description

[0028] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0029] Figure 1 The mechanical properties of the R-PET sample prepared in accordance with GB / T 1040.2-2006 and the film prepared in Example 1 are shown in the figure.

[0030] Figure 2 The infrared spectra are for R-PET, Example 1 of the present invention, and Comparative Examples 1 and 2.

[0031] Figure 3 Differential scanning calorimetry test images of R-PET, Example 1 of the present invention, and Comparative Examples 1 and 2.

[0032] Figure 4 The steady-state fluorescence (PL) spectra of the materials in Example 1 and Comparative Examples 1-4 of this invention are shown.

[0033] Figure 5 The diagram shows the afterglow of different materials prepared using R-PET@COR blends in Examples 1-3 of this invention. Detailed Implementation

[0034] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0035] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0036] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0037] Unless otherwise specified, all raw materials used in this invention are commercially available in the field. The waste PET used comes from waste transparent mineral water bottles, and the organic light-emitting material used has the structural formula shown in Formula A.

[0038]

[0039] In this invention, the afterglow properties of the material are tested using a steady-state / transient fluorescence spectrometer. Steady-state PL spectra, delayed emission spectra, absolute PL yield, kinetic emission decay curves, and time-resolved emission decay curves are collected.

[0040] Example 1

[0041] This embodiment provides a method for preparing long afterglow materials based on waste PET, specifically:

[0042] 1) Waste PET is crushed, washed, and dried to obtain pretreated waste PET material, denoted as R-PET;

[0043] 2) Waste PET material and crown ore (COR) compound are added to a mixer for blending. The amount of crown ore (COR) compound added to the waste PET material is 0.1 wt%. The melt temperature is set to 265℃, the rotation speed is set to 30 r / min, and the blending time is 15 min. The resulting blend is denoted as R-PET@COR.

[0044] 3) After the blend is dried, it is placed in a flat vulcanizing machine for processing. The temperature of the upper and lower layers of the flat vulcanizing machine is set to 270°C, the pre-compression pressure is set to 2MPa, and the time is 20s. After R-PET@COR melts, the pressure is set to 12MPa and the pressure time is 30s. After the pressure treatment is completed, it is quickly transferred to a room temperature water bath to achieve quenching treatment, thus obtaining the transparent R-PET@COR film of this embodiment.

[0045] Figure 1 Referring to the mechanical property diagrams of the R-PET samples prepared in GB / T 1040.2-2006 and the films prepared in this embodiment, it can be seen that the mechanical properties of the R-PET long afterglow material prepared in Example 1 are comparable to those of the recycled R-PET material, indicating that the preparation of the R-PET long afterglow material is not affected by the doping of organic light-emitting substances.

[0046] Comparative Example 1

[0047] The difference between this comparative example and Example 1 is that the organic light-emitting material crown olefin (COR) in step 2) is changed to pyrene (Py). The remaining steps are the same as in Example 1, thus obtaining the transparent R-PET@Py film of this comparative example.

[0048] Comparative Example 2

[0049] The difference between this comparative example and Example 1 is that the organic light-emitting material crown olefin (COR) in step 2) is changed to fluoroanthracene (FA), while the remaining steps are the same as in Example 1, thus obtaining the transparent R-PET@FA film of this comparative example.

[0050] Figure 2 The infrared spectra of R-PET and Examples 1, 1 Comparative Example, and 2 are shown. Figure 3 Differential scanning calorimetry (DSC) results for R-PET and Examples 1, 1, and 2 (Comparative Example 1 and 2) are shown. Figure 2 It can be seen that the characteristic absorption peak of the benzene ring appeared after doping with organic light-emitting materials, and the structure of R-PET itself is not affected. Figure 3 It can be seen that the incorporation of organic light-emitting materials did not affect the melting point and processing temperature of R-PET.

[0051] Comparative Example 3

[0052] The difference between this comparative example and Example 1 is that the organic light-emitting material crown olefin (COR) in step 2) is changed to triphenylene (TP). The remaining steps are the same as in Example 1, thus obtaining the transparent R-PET@TP film of this comparative example.

[0053] Comparative Example 4

[0054] The difference between this comparative example and Example 1 is that the organic light-emitting material crown olefin (COR) in step 2) is changed to phenanthrene (PA). The remaining steps are the same as in Example 1, thus obtaining the transparent R-PET@PA film of this comparative example.

[0055] Figure 4 The steady-state fluorescence (PL) spectra of the materials in Example 1 and Comparative Examples 1-4 show that each doped organic light-emitting R-PET material undergoes electronic transitions at different excitation wavelengths.

[0056] Comparative Example 5

[0057] The difference between this comparative example and Example 1 is that the organic light-emitting material crown olefin (COR) in step 2) is changed to biphenyl (BP), while the remaining steps are the same as in Example 1, thus obtaining the transparent R-PET@BP film of this comparative example.

[0058] Comparative Example 6

[0059] The difference between this comparative example and Example 1 is that the organic light-emitting material crown olefin (COR) in step 2) is changed to naphthalene (NP). The remaining steps are the same as in Example 1, thus obtaining the transparent R-PET@NP film of this comparative example.

[0060] The long afterglow ability of the R-PET@PA films prepared in Comparative Example 1 and Comparative Examples 1-6 is shown in Table 1.

[0061] Table 1

[0062]

[0063]

[0064] As can be seen from Table 1, the choice of COR as a luminescent compound has significant advantages over other types of polycyclic aromatic hydrocarbons. COR is a fused-ring aromatic hydrocarbon consisting of six benzene rings linked in a six-membered ring. Its molecular structure, compared to the planar and rigid chemical structures of other luminescent compounds in the table, is more conducive to suppressing intramolecular motion when combined with PET, thereby reducing nonradiative decay channels and better suppressing the nonradiative transition of molecules from the triplet excited state to the ground state, thus exhibiting a longer afterglow effect.

[0065] Example 2

[0066] The difference between this embodiment and Embodiment 1 is that step 3) is adjusted to obtain filaments from the blend using a micro conical twin-screw extruder. Specifically:

[0067] After drying, the R-PET@COR blend is processed into filaments using a micro conical twin-screw extruder at 275°C and designed as a five-pointed star to be sewn into the clothing pattern.

[0068] Example 3

[0069] The difference between this embodiment and Embodiment 1 is that step 3) is adjusted to process the blend using a cotton candy machine to obtain fibrous cotton candy. Specifically:

[0070] R-PET@COR blends are dried and processed using a cotton candy machine with an output temperature set at 270℃ and a rotation speed of 2500rpm. The flexible filaments formed by air cooling in the collection chamber are hand-wound onto bamboo sticks to produce fibrous cotton candy, which is then used to weave Chinese knots.

[0071] Figure 5 The diagram shows the afterglow of different materials prepared using R-PET@COR blends in Examples 1-3 of this invention.

[0072] Example 4

[0073] This embodiment is used to investigate the effect of the doping amount of different organic light-emitting substances relative to R-PET on the luminescence performance of the prepared materials. The difference from Example 1 is that the doping amount of COR relative to R-PET in step 2) is adjusted to 0.01wt%, 0.05wt%, 0.1wt%, 0.5wt%, 1wt%, and 2wt%, respectively. The remaining steps are the same as in Example 1. Light-emitting materials with different COR doping amounts are obtained in this embodiment, and the luminescence performance is measured. The results are shown in Table 2.

[0074] Table 2

[0075] COR doping concentration / wt% 245nm irradiation / s 310nm irradiation / s 380nm irradiation / s 0.01 38.7 41.3 45.3 0.05 43.8 48.5 51.2 0.1 39.4 45.6 48.1 0.5 38.6 43.1 46.5 1 31.9 35.2 39.4 2 22.8 27.4 32.3

[0076] As can be seen from Table 2, when the COR doping concentration is too low, the number of organic molecules that absorb light and generate excitons is too small. Even if each exciton has a long lifetime, the overall luminescence intensity will be very weak. On the other hand, excessively high doping concentration can easily lead to the aggregation of organic long-afterglow molecules in the polymer matrix, resulting in a decrease in afterglow brightness.

[0077] In summary, this invention uses crown olefins, an organic luminescent material, as the luminescent molecule, and melt-dops it into recycled waste PET, thus upgrading and remanufacturing waste PET into a long-lasting luminescent polymer element. The PET macromolecular chains fold back and forth to form regular sheets, stabilizing excitons and preventing atmospheric oxygen quenching. Polycyclic aromatic hydrocarbons, due to their planar and rigid structure, help suppress intramolecular motion, thereby reducing non-radiative decay channels and achieving an ultra-long afterglow effect. The long afterglow material of this invention reduces waste pollution, achieves resource upgrading and reuse, and the upgrading and recycling process is simple, convenient, and low-cost. The preparation process is easily scalable, economical, and efficient, showing great promise for industrial application and possessing significant application value in the field of plastic upgrading and recycling technology.

[0078] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A long afterglow material based on waste PET, characterized in that: The long afterglow material is obtained by blending waste PET with the structure shown in Formula I and crownene, an organic light-emitting substance with the structure shown in Formula II. In Formula I, the value of n ranges from 50 to 200, and the doping amount of the organic luminescent material crownene relative to waste PET is 0.01 to 2 wt%.

2. The method for preparing long afterglow material based on waste PET as described in claim 1, characterized in that: include, Waste PET is crushed, washed, and dried to obtain R-PET; R-PET and crownene are added to a mixer and blended to obtain a blend R-PET@COR with a crownene doping amount of 0.01 to 2 wt% relative to R-PET. R-PET@COR can be further processed to obtain long afterglow luminescent materials in different forms.

3. The method for preparing long afterglow material based on waste PET as described in claim 2, characterized in that: The blending process involves a melt temperature of 250–300°C in an internal mixer, a rotation speed of 10–60 r / min, and a blending time of 1–20 min.

4. The method for preparing long afterglow material based on waste PET as described in claim 2, characterized in that: The post-processing includes processing using one of a flat vulcanizing machine, a twin-screw extruder, or a cotton candy machine to obtain film-like, filament-like, or fiber-like luminescent materials, respectively.

5. The method for preparing long afterglow material based on waste PET as described in claim 4, characterized in that: The processing via a flat vulcanizing machine includes a plate temperature of 250–300°C, a pre-compression pressure of 0–12 MPa, a pre-compression time of 0–60 s, an additional pressure of 0–14 MPa, and an additional compression time of 0–60 s.

6. The method for preparing long afterglow material based on waste PET as described in claim 4, characterized in that: The processing is carried out by a twin-screw extruder, wherein the temperature of the twin-screw extruder is 250-300°C.

7. The method for preparing long afterglow material based on waste PET as described in claim 4, characterized in that: The output temperature of the cotton candy machine is 260℃~280℃, and the centrifugal speed is 2200~2600rpm.

8. The long afterglow luminescent material prepared by the method for preparing long afterglow material based on waste PET as described in claim 2 is used in the preparation of information encryption and anti-counterfeiting materials, packaging materials, and textiles and clothing.

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