Method for preparing passive cooling film from recycled plastic bottles and passive cooling film

Abstract

The invention discloses a method for preparing a passive cooling film from recycled plastic bottles and the passive cooling film, and belongs to the field of compositions of high-molecular compounds. The method comprises the steps that PET of recycled plastic bottle bodies and a solvent are mixed and subjected to electrostatic spinning, and a PET film is obtained; forming a PE film on the surface of the PET film to obtain a passive cooling film; and the PE film comprises PE of recycled plastic bottle caps. The passive cooling film solves the problem that a single PET spinning film is poor in mechanical property, so that the passive cooling film is more stable and reliable in practical application; according to the method, recycling of the waste plastic bottles is achieved, plastic pollution is reduced, the film capable of being passively cooled is successfully prepared, the concept of sustainable development is met, and a new way is provided for high-value recycling of plastic waste while energy consumption is reduced.

Description

Technical Field

[0001] This application relates to the field of compositions of polymer compounds, and particularly to a method for preparing a passive cooling film from recycled plastic bottles and a passive cooling film. Background Art

[0002] Globally, plastic pollution has become an increasingly severe environmental problem. A large number of plastic products, especially plastic bottles, are discarded randomly after use and accumulate in landfills, natural water bodies, and soil. They are difficult to degrade and pose a serious threat to the ecosystem and human health. At the same time, with global warming, energy consumption is constantly rising. Traditional cooling means such as air conditioners and electric fans not only consume huge amounts of energy but also produce greenhouse gas emissions, exacerbating environmental problems. Therefore, finding a method that can solve plastic pollution and achieve energy-saving cooling has important practical significance. As an emerging green cooling technology, passive cooling materials have received extensive attention in recent years. Its principle is to utilize the thermophysical properties of the material to achieve cooling without heat input by reflecting sunlight and thermal radiation (by the high emissivity of the material in a specific wavelength band, dissipating heat in the form of infrared radiation into outer space). Therefore, if plastic bottles can be recycled to prepare materials with passive cooling functions, it can solve plastic pollution while being applied in the cooling field to reduce energy consumption.

[0003] In the prior art, some studies have attempted to use waste plastics to prepare functional materials. However, most studies directly use waste plastic bottle fragments to prepare thermal insulation materials. This method mainly focuses on thermal insulation performance, does not involve passive cooling function, and does not classify and utilize different parts of plastic bottles, so it cannot give full play to the advantages of each part of the material. In addition, some studies have improved the reflectivity of materials by adding reflective fillers such as titanium dioxide to achieve passive cooling, but they do not use recycled plastic bottles as raw materials and do not couple passive cooling with the recycling of waste plastic bottles. The passive cooling films prepared from single materials have deficiencies in optical and mechanical properties and are difficult to meet the requirements of diverse application scenarios; they fail to effectively integrate the recycling of waste plastic bottles with the realization of passive cooling function and cannot solve plastic pollution and energy consumption problems simultaneously.

[0004] Therefore, developing a method that can use the bottle body and bottle cap of waste plastic bottles to prepare a passive cooling film is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the present application provides a passive cooling film made of polyethylene terephthalate (PET)-polyethylene (PE) double-layer composite film based on waste plastic bottles, which realizes high solar reflectivity and relatively high mechanical strength through multi-scale structural design (PET porous layer and TiO2-reinforced PE layer), while recycling PET and PE and coupling passive cooling with waste plastic bottle recycling.

[0006] The present application provides a method for preparing a passive cooling film from recycled plastic bottles, including: Mixing PET from the recycled plastic bottle body with a solvent and electrospinning to obtain a PET film; Forming a PE film on the surface of the PET film to obtain a passive cooling film; the PE film includes PE from the recycled plastic bottle cap.

[0007] In some specific implementation manners, the method for preparing the PE film includes: Melting and blending PE from the recycled plastic bottle cap with titanium dioxide to obtain a PE film.

[0008] In some specific implementation manners, the mass ratio of the PE from the recycled plastic bottle cap to titanium dioxide is (8-10):1; the particle size of the titanium dioxide is 300 nm to 500 nm.

[0009] In some specific implementation manners, the temperature of the melting and blending is 160 °C to 200 °C, the rotation speed of the melting and blending is 50 r / min to 100 r / min, and the time of the melting and blending is 8 min to 20 min.

[0010] In some specific implementation manners, the thickness of the PET film is 20 μm to 200 μm; the thickness of the PE film is 150 μm to 200 μm.

[0011] In some specific implementation manners, the mass ratio of the PET from the recycled plastic bottle body to the solvent is (1-10):20; the solvent includes trifluoroacetic acid and dichloromethane; the volume ratio of trifluoroacetic acid to dichloromethane is (1-3):1.

[0012] In some specific implementation manners, the voltage of the electrospinning is 15 kV to 25 kV, the receiving distance of the electrospinning is 10 cm to 20 cm, the temperature of the electrospinning is 20 °C to 30 °C, and the humidity of the electrospinning is 40% to 60%.

[0013] In some specific implementation manners, the method for forming the PE film includes using an adhesive to bond the PET film and the PE film, and the thickness of the adhesive is 5 μm to 12 μm.

[0014] The present application also provides a passive cooling film, which includes a PET film and a PE film arranged in sequence; the PET film includes PET recycled from plastic bottle bodies; the PE film includes PE recycled from plastic bottle caps.

[0015] In some specific implementation manners, the PET film has a porous structure; the PE film includes 8 to 10 parts by mass of PE recycled from plastic bottle caps and 1 part of titanium dioxide.

[0016] The method of the present application for preparing a passive cooling composite film by recycling waste plastic bottles separates the bottle bodies (PET) and bottle caps (PE) of waste plastic bottles, and respectively prepares PET and PE films by electrospinning and melt blending and pressing, and then prepares a cooling composite film by bonding. During the preparation process, the porous PET film and the PE film added with titanium dioxide can effectively improve the reflectivity and emissivity of sunlight, thereby significantly enhancing the passive cooling ability. At the same time, the composite film material also solves the problem of poor mechanical properties of a single PET spun film, making it more stable and reliable in practical applications. The preparation method described in the present application not only realizes the recycling of waste plastic bottles, reduces plastic pollution, but also successfully prepares a film capable of passive cooling, which conforms to the concept of sustainable development, reduces energy consumption while providing a new way for the high-value reuse of plastic waste. Description of the Drawings

[0017] Figure 1 It is a schematic structural diagram of the passive cooling film provided in Embodiment 1 of the present application; Figure 2 It is a scanning electron microscope image of the PET film provided in Embodiment 1 of the present application. Detailed Description of the Embodiments

[0018] It should be understood that the expression "one or more of..." individually includes each of the objects recited after the expression and various different combinations of two or more of the recited objects, unless otherwise understood from the context and usage. The expression "and / or" in combination with three or more recited objects should be understood to have the same meaning, unless otherwise understood from the context.

[0019] The terms "comprising", "having" or "containing", including the use of their grammatical synonyms, should generally be understood as open and non-limiting, for example, not excluding other unrecited elements or steps, unless specifically stated otherwise or understood from the context.

[0020] It should be understood that as long as the present application can still operate, the order of steps or the order of performing certain actions is not important. In addition, two or more steps or actions can be performed simultaneously.

[0021] Any and all examples or use of exemplary language such as "for example" or "including" in this document are merely intended to better illustrate the present application and do not limit the scope of the present application. No language in this specification should be construed as indicating that any unclaimed element is essential for the practice of the present application.

[0022] In addition, the numerical ranges and parameters used to define the present application are approximate values. The relevant numerical values in specific embodiments have been presented as precisely as possible herein. However, any numerical value inherently and inevitably contains standard deviations due to individual testing methods. Therefore, unless otherwise clearly stated, it should be understood that all ranges, quantities, numerical values, and percentages used in this disclosure are modified by "about". Here, "about" generally means that the actual value is within plus or minus 10%, 5%, 1%, or 0.5% of a specific numerical value or range.

[0023] The present application provides a method for recycling plastic bottles to prepare a passive cooling film, including: Mixing PET from the recycled plastic bottle body with a solvent for electrospinning to obtain a PET film; Forming a PE film on the surface of the PET film to obtain a passive cooling film; the PE film includes PE from the recycled plastic bottle cap.

[0024] The present application first mixes PET from the recycled plastic bottle body with a solvent for electrospinning to obtain a PET film. In some specific implementation manners, the PET from the recycled plastic bottle body is cut into 10mm*10mm squares, washed with ethanol, and dried. The drying temperature is 40°C to 60°C; the dried PET is mixed with a solvent to prepare a PET solution. In some specific implementation manners, the mass ratio of the PET from the recycled plastic bottle body to the solvent is (1-10):20; the solvent includes but is not limited to trifluoroacetic acid and / or dichloromethane, and the present application has no special requirements for the selection of the solvent; the volume ratio of trifluoroacetic acid to dichloromethane is (1-3):1, preferably 2:1. In some specific implementation manners, the PET film is prepared by electrospinning the PET solution. In some specific implementation manners, the voltage of the electrospinning is 15kV to 25kV, preferably 20KV; the receiving distance of the electrospinning is 10cm to 20cm, preferably 15cm; the temperature of the electrospinning is 20°C to 30°C, preferably 25°C, and the humidity of the electrospinning is 40% to 60%, preferably 50%. The feeding speed is 1mL / h, and the needle is of model 23G (inner diameter 0.36mm, outer diameter 0.63mm). In some specific implementation manners, the thickness of the PET film is 20μm to 200μm.

[0025] The present application then melt-blends the PE of the recycled plastic bottle caps with titanium dioxide to obtain a PE film. In some specific implementation manners, the mass ratio of the PE of the recycled plastic bottle caps to titanium dioxide is (8 - 10):1, preferably 9:1; the particle size of the titanium dioxide is 300 nm to 500 nm. In some specific implementation manners, the temperature of the melt-blending is 160°C to 200°C, the rotation speed of the melt-blending is 50 r / min to 100 r / min, and the time of the melt-blending is 8 min to 20 min. In some specific implementation manners, after the melt-blending, tableting is performed to obtain a PE film, the temperature of the tableting is 150°C to 170°C, preferably 160°C; the pressure of the tableting is 5 MPa to 7 MPa, preferably 6 MPa; the time of the tableting is 2 min to 4 min, preferably 3 min. In some specific implementation manners, the thickness of the PE film is 150 μm to 200 μm.

[0026] The present application then forms a PE film on the surface of the PET film to obtain a passive cooling film. In some specific implementation manners, the method of forming the PE film includes using an adhesive to bond the PET film and the PE film, and the thickness of the adhesive is 5 μm to 12 μm.

[0027] Compared with the prior art, the present application can realize the simultaneous utilization of the bottle body and bottle caps of waste plastic bottles, and can use recycled plastic bottles to prepare a passive cooling film, and this film also has a double-layer structure and can flexibly adjust the passive cooling ability and mechanical properties according to actual needs.

[0028] The present application also provides a passive cooling film, including a PET film and a PE film arranged in sequence; the PET film includes the PET of the recycled plastic bottle body; the PE film includes the PE of the recycled plastic bottle caps. The structural schematic diagram of the passive cooling film is as Figure 1As described above, 1 is a PET film. In some specific implementation manners, the thickness of the PET film is 20 μm to 200 μm. The PET film is a porous structure and includes PET filaments; 2 is a PE film. In some specific implementation manners, the thickness of the PE film is 150 μm to 200 μm. The PE film includes 8 to 10 parts by mass of PE from recycled plastic bottle caps (which can be 8 parts, 8.5 parts, 9 parts, 9.5 parts, 10 parts) and 1 part of titanium dioxide. The working principle of the passive cooling film is that the upper PET film is prepared by electrospinning, so it is a porous structure with a high reflectivity, but the mechanical properties of the film are poor. The lower PE film has high mechanical properties but a low reflectivity. Therefore, TiO2 is added to the lower PE layer to improve the reflectivity. Then, the PET film is bonded to the PE-TiO2 layer to improve the mechanical properties of the double-layer film. A passive cooling double-layer film with a high reflectivity and good mechanical properties is successfully prepared from recycled plastic bottles. The passive cooling film is prepared by using recycled plastic bottles, and the thickness of the upper and lower layers of the prepared passive cooling film can be flexibly adjusted according to different application requirements. The passive cooling film is applicable to fields such as outdoor thermal management, human thermal management, and building thermal management, can effectively reduce energy consumption, and achieve sustainable development.

[0029] The method of the present application for preparing a passive cooling composite film by recycling waste plastic bottles separates the bottle body (PET) and the bottle cap (PE) of the waste plastic bottle, and respectively prepares PET and PE films by electrospinning and melt blending and pressing. Then, a cooling composite film is prepared by bonding. During the preparation process, the porous PET film and the PE film added with titanium dioxide can effectively improve the reflectivity and emissivity of sunlight, thereby significantly enhancing the passive cooling ability. At the same time, the composite film material also solves the problem of poor mechanical properties of a single PET spun film, making it more stable and reliable in practical applications. The preparation method described in the present application not only realizes the recycling of waste plastic bottles, reduces plastic pollution, but also successfully prepares a film that can passively cool, conforms to the concept of sustainable development, provides a new way for the high-value reuse of plastic waste while reducing energy consumption.

[0030] The following further elaborates the present application in conjunction with embodiments. The protection scope of the present application is not limited by the following embodiments. Example 1

[0031] This example provides a method for preparing a passive cooling film from recycled plastic bottles, including: First, cut the PET of the recycled plastic bottle body into 10 mm * 10 mm squares, wash them with ethanol, and then put them in an oven at 40 °C for drying; Weigh 5 g of PET and add it to a mixed solution of 45 g of trifluoroacetic acid - dichloromethane (30 g of trifluoroacetic acid and 15 g of dichloromethane), stir and dissolve it at room temperature to prepare a PET solution with a concentration of 10 wt%; Adjust the electrospinning parameters: the process parameter voltage is 20 KV, the receiving distance is 15 cm, the temperature is 25 °C, the humidity is 50%, the feeding speed is 1 mL / h, the needle head model is 23G (inner diameter: 0.36 mm, outer diameter 0.63 mm), and a 20 - μm PET film is prepared by electrospinning; Wash the PE of the recycled plastic bottle cap with ethanol and dry it in an oven at 40 °C; add 6 g of TiO₂ (particle size: 400 nm) to 54 g of the dried PE and carry out melt blending at 180 °C and a rotation speed of 60 r / min for 10 min to ensure uniform mixing; use a tablet press to press the blended PE - TiO₂ into a PE film at 160 °C and a pressure of 6 MPa for 3 min, and the thickness of the PE film is 200 μm; Cut the above - mentioned PET film and PE film into the same size, place the PET film on the upper layer and the PE film on the lower layer, and bond them using an adhesive. The coating amount of the adhesive is 10 μm to obtain a passive cooling film. The scanning electron micrograph of the PET film provided in this example is as Figure 2 shown. Example 2

[0032] This example provides a method for preparing a passive cooling film from recycled plastic bottles. The difference from Example 1 is that the thickness of the PET film is 80 μm. Example 3

[0033] This example provides a method for preparing a passive cooling film from recycled plastic bottles. The difference from Example 1 is that the thickness of the PET film is 120 μm. Example 4

[0034] This example provides a method for preparing a passive cooling film from recycled plastic bottles. The difference from Example 1 is that the thickness of the PET film is 200 μm. Example 5

[0035] This example provides a method for preparing a passive cooling film from recycled plastic bottles, including: First, cut the PET on the recycled plastic bottle body into 10 - mm * 10 - mm squares, wash them with ethanol, and then put them into an oven at 40 °C for drying; Weigh 5 g of PET and add it to a mixed solution of 45 g of trifluoroacetic acid - dichloromethane (30 g of trifluoroacetic acid and 15 g of dichloromethane), stir and dissolve it at room temperature to prepare a PET solution with a concentration of 10 wt%; Adjust the electrospinning parameters. The process parameters are as follows: voltage 20 KV, receiving distance 15 cm, temperature 25 °C, humidity 50%, feeding speed 1 mL / h, needle model 23G (inner diameter: 0.36 mm, outer diameter 0.63 mm). A 20-μm PET film is prepared by electrospinning. Wash the PE from the recycled plastic bottle caps with ethanol and dry it in an oven at 40 °C. Press the dried PE into a PE film at 160 °C under a pressure of 6 MPa for 3 min using a tablet press. The thickness of the PE film is 200 μm. Cut the above PET film and PE film into the same size. Place the PET film on the upper layer and the PE film on the lower layer, and bond them using an adhesive. The coating amount of the adhesive is 10 μm to obtain a passive cooling film. Example 6

[0036] This example provides a method for preparing a passive cooling film from recycled plastic bottles. The difference from Example 1 is that the mass ratio of PE from the recycled plastic bottle caps to titanium dioxide is 8:1. Example 7

[0037] This example provides a method for preparing a passive cooling film from recycled plastic bottles. The difference from Example 1 is that the mass ratio of PE from the recycled plastic bottle caps to titanium dioxide is 10:1. Example 8

[0038] This example provides a method for preparing a passive cooling film from recycled plastic bottles. The difference from Example 1 is that the electrospinning receiving distance is 10 cm, the electrospinning voltage is 15 kV, the electrospinning temperature is 20 °C, and the electrospinning humidity is 40%. Example 9

[0039] This example provides a method for preparing a passive cooling film from recycled plastic bottles. The difference from Example 1 is that the electrospinning receiving distance is 20 cm, the electrospinning voltage is 25 kV, the electrospinning receiving distance is 20 cm, the electrospinning temperature is 30 °C, and the electrospinning humidity is 60%. Example 10

[0040] This example provides a method for preparing a passive cooling film from recycled plastic bottles. The difference from Example 1 is that the mass fraction of PET is 8 wt%, and the volume ratio of trifluoroacetic acid to dichloromethane is 3:1. Example 11

[0041] This example provides a method for preparing a passive cooling film from recycled plastic bottles. The difference from Example 1 is that the mass fraction of PET is 15 wt%, and the volume ratio of trifluoroacetic acid to dichloromethane is 1:1.

[0042] Performance tests were conducted on the PET films, PE films, and passive cooling films provided in Examples 1-11. The test methods are as follows: Reflectance: An ultraviolet-visible-near-infrared tester was used to measure the reflectance of the material at intervals of 5 nm in the wavelength range of 200-2500 nm. The data obtained from the test was calculated using the following formula to calculate the reflectance. The surface of the passive cooling film on the PET film side was tested.

[0043]

[0044] is the reflectance; is the spectral reflectance of the standard whiteboard; is the spectral reflectance of the sample; is the relative spectral distribution of solar radiation (refer to the table of relative spectral distribution of standard solar radiation); is the wavelength interval.

[0045] The test results are shown in Table 1.

[0046]

[0047] As can be seen from Table 1 and Examples 1-4, as the thickness of the PET film increases, the reflectance increases accordingly. From Examples 1 and 5, it can be seen that adding TiO2 to PE can effectively increase the reflectance of the material. From Examples 1, 2, and 6, it can be seen that the reflectance of the prepared double-layer film is higher than that of any single-layer film. Therefore, it is feasible to prepare a double-layer film using PET and PE-TiO2, and the thickness of each layer can be adjusted according to actual needs to optimize the passive cooling ability and mechanical properties. The raw material of the prepared passive cooling double-layer film is derived from recycled plastic bottles. This film is suitable for outdoor thermal management, human thermal management, building thermal management and other fields, which can effectively reduce energy consumption and achieve sustainable development.

[0048] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application, according to the technical solution of the present application and its application concept, makes equivalent substitutions or changes, and should be covered by the protection scope of the present application.

Claims

1. A method for preparing a passive cooling film by recycling plastic bottles, characterized in that: include: The PET from recycled plastic bottles is mixed with a solvent and electrospun to obtain a PET film; A PE film is formed on the surface of a PET film to obtain a passive cooling film; the PE film comprises PE recycled from plastic bottle caps.

2. The method according to claim 1, characterized in that The preparation method of the PE film comprises: The PE from recycled plastic bottle caps is melt-blended with titanium dioxide to obtain a PE film.

3. The method according to claim 2, characterized in that The mass ratio of PE to titanium dioxide in the recycled plastic bottle cap is (8-10):1; the particle size of the titanium dioxide is 300nm to 500nm.

4. The method according to claim 2, characterized in that: The temperature of the melt blending is 160° C. to 200° C., the rotation speed of the melt blending is 50 r / min to 100 r / min, and the time of the melt blending is 8 min to 20 min.

5. The method according to claim 1, characterized in that The thickness of the PET film is 20 μm to 200 μm; the thickness of the PE film is 150 μm to 200 μm.

6. The method according to claim 1, characterized in that The mass ratio of the PET of the recycled plastic bottle body to the solvent is (1-10):20; the solvent includes trifluoroacetic acid and dichloromethane; the volume ratio of the trifluoroacetic acid to dichloromethane is (1-3):

1.

7. The method according to claim 1, characterized in that The voltage of the electrospinning is 15 kV to 25 kV, the receiving distance of the electrospinning is 10 cm to 20 cm, the temperature of the electrospinning is 20° C. to 30° C., and the humidity of the electrospinning is 40% to 60%.

8. The method according to claim 1, characterized in that The method of forming the PE film includes bonding the PET film and the PE film using an adhesive, wherein the thickness of the adhesive is 5 μm to 12 μm.

9. A passive cooling film, characterized in that: It comprises a PET film and a PE film which are arranged in sequence; the PET film comprises PET from recycled plastic bottle bodies; and the PE film comprises PE from recycled plastic bottle caps.

10. The passive cooling film according to claim 9, characterized in that: The PET film is a porous structure; the PE film comprises 8 to 10 parts of PE from recycled plastic bottle caps and 1 part of titanium dioxide by mass.

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