Heat insulation window film and preparation method thereof

Abstract

The invention relates to a heat insulation window film and a preparation method thereof, the heat insulation window film comprises a protective layer, a barrier layer, a pressure-sensitive adhesive layer and a release film layer, the barrier layer comprises PET resin, a carbon nanotube compound, epoxy resin, composite nanoparticles and a curing agent; the carbon nano tube compound comprises a modified carbon nano tube, polylactic acid and poly (butylene adipate-co-terephthalate). The automobile film has the effect of improving the heat insulation performance and strength of the automobile film.

Description

Technical Field

[0001] This application relates to the field of heat-insulating window films, and particularly to a heat-insulating window film and a preparation method thereof. Background Art

[0002] A window film is a multi-layered and multi-functional polyester composite optical-grade special film product, which is pasted on the glass surface to improve the performance and strength of the glass, making it have functions such as explosion-proof, privacy shielding, and safety protection.

[0003] When driving in hot weather, ordinary window films are difficult to further block heat and infrared rays. When sunlight shines on people's skin, it will cause the skin temperature to rise rapidly, exacerbate the loss of skin moisture, make the skin dry and rough, and the heat will also affect people's concentration, so there is room for improvement. Summary of the Invention

[0004] In order to further improve the heat-insulating performance of the window film, this application provides a heat-insulating window film and a preparation method thereof.

[0005] A heat-insulating window film and a preparation method thereof provided by this application adopt the following technical solutions: In the first aspect, a heat-insulating window film provided by this application adopts the following technical solutions: A heat-insulating window film includes a protective layer, a barrier layer, a pressure-sensitive adhesive layer, and a release film layer. The barrier layer includes PET resin, carbon nanotube composite, epoxy resin, composite nanoparticles, and a curing agent; the carbon nanotube composite includes modified carbon nanotubes, polylactic acid, and poly(butylene adipate-co-terephthalate).

[0006] By adopting the above technical solutions, the carbon nanotube composite is prepared from modified carbon nanotubes, polylactic acid, and poly(butylene adipate-co-terephthalate). Carbon nanotubes have a unique nanostructure, good mechanical and thermal properties, and high reflectivity in the infrared band, capable of absorbing and scattering infrared rays, thereby blocking infrared rays and further achieving a heat-insulating effect; polylactic acid is a rigid polymer, and poly(butylene adipate-co-terephthalate) has good elasticity and excellent biodegradability, capable of blending with polylactic acid. After being compounded with modified carbon nanotubes, a polymer composite with balanced mechanical properties can be obtained, making the prepared heat-insulating film have good thermomechanical, chemical, and physical properties, and further improving the overall strength and heat-insulating performance of the prepared window film.

[0007] Preferably, the modified carbon nanotubes include carboxylated carbon nanotubes and polyethyleneimine.

[0008] By adopting the above technical solution, polyethyleneimine has a three-dimensional dendritic structure and is a flexible polymer. It is rich in primary amine and secondary amine groups. After binding to carboxylated carbon nanotubes, it can improve the dispersion performance of carboxylated carbon nanotubes in the system and can further bind to epoxy resin to enhance the overall stability of the system.

[0009] Preferably, the modified carbon nanotubes are prepared by the following method: Mix polyethyleneimine with water to obtain a polyethyleneimine solution. Add carboxylated carbon nanotubes to the polyethyleneimine solution to obtain a carbon nanotube dispersion. Subject the carbon nanotube dispersion to condensation reflux in an oil bath environment, vacuum filtration, washing, and drying to obtain modified carbon nanotubes.

[0010] By adopting the above technical solution, the amino group of polyethyleneimine and the carboxyl group of carboxylated carbon nanotubes undergo an amidation reaction to form an amide bond, so that polyethyleneimine is grafted onto the surface of carboxylated carbon nanotubes. The dendritic polymer polyethyleneimine can effectively improve the dispersion effect of carboxylated carbon nanotubes in the system and can participate in the curing cross-linking reaction of epoxy resin, further improving the interfacial bonding effect between carbon nanotubes and the epoxy resin matrix, thereby further enhancing the overall stability of the system.

[0011] Preferably, the carbon nanotube composite is prepared by the following method: Mix polylactic acid, poly(butylene adipate terephthalate) and modified carbon nanotubes, and stir under water bath conditions to obtain a reactant. After melting, extrusion, and injection molding, a carbon nanotube composite is obtained.

[0012] Poly(butylene adipate terephthalate) can induce nucleation, thereby increasing the crystallinity, making the modified carbon nanotubes further uniformly dispersed in the system, thus reducing the occurrence of defects in the system and further enhancing the overall stability of the system. The mechanical properties and stability of the prepared heat-insulating film are improved.

[0013] Preferably, the mass ratio among polylactic acid, poly(butylene adipate terephthalate) and modified carbon nanotubes is 3.5:1:(0.27 - 0.33).

[0014] By adopting the above technical solution, preferably, when the mass ratio among polylactic acid, poly(butylene adipate terephthalate) and modified carbon nanotubes is within the above range, the stability of the prepared modified carbon nanotubes can be further enhanced.

[0015] Preferably, the mass ratio between the carbon nanotube composite and epoxy resin is 1:(4 - 5).

[0016] By adopting the above technical solution, preferably, the mass ratio between the carbon nanotube composite and the epoxy resin is within the above range, which can further improve the binding performance and stability among the components in the system.

[0017] Preferably, the composite nanoparticles include silica, titanium dioxide and fluoroalkylsilane.

[0018] By adopting the above technical solution, titanium dioxide is an oxide with good chemical properties, having good stability, and having antifouling self-cleaning and anti-corrosion properties. Introducing silica as a carrier can further reduce the agglomeration phenomenon of titanium dioxide in the system, and can construct a nano-micron two-layer structure, reducing the proportion of the wetted surface, increasing the roughness, and further improving the overall hydrophobic property of the system. However, under sunlight irradiation, it is easy to lose the hydrophobic property. After adding fluoroalkylsilane, it can hydrolyze and crosslink in the system to form a solid film and a catalyst-free self-healing additive, restoring the hydrophobic property of the system under ultraviolet light, further improving the hydrophobic stability of the system, and can cooperate with the carbon nanotube composite to fill the resin system to improve the binding performance, heat insulation performance and mechanical strength of the system.

[0019] Preferably, the composite nanoparticles are prepared by the following method: Mix titanium sulfate with water, add nano-titanium dioxide powder, stir and add ammonia water for hydrolysis to obtain a precipitate. Filter and wash the precipitate, then disperse the precipitate in water, add nitric acid to obtain a silica composite sol, dry and calcine to obtain silica composite titanium dioxide; mix absolute ethanol, toluene and fluoroalkylsilane, add silica composite titanium dioxide, ultrasonically disperse, centrifuge and wash, and dry to obtain composite nanoparticles.

[0020] By adopting the above technical solution, using silica microspheres as a carrier, titanium dioxide is loaded on silica by hydrothermal method, and the agglomeration of titanium dioxide is significantly improved. Due to the curvature of titanium dioxide and the existence of Ti-O-Si bonds, the further growth of titanium dioxide particles is inhibited, making the particle diameter smaller and evenly coated on the surface of silica, forming micro-nano particles with a certain roughness, and effectively improving the loading rate and the overall stability of the prepared composite nanoparticles.

[0021] Preferably, the mass ratio between the composite nanoparticles and the carbon nanotube composite is (1.5 - 1.4):1.

[0022] By adopting the above technical solution, preferably, the mass ratio between the composite nanoparticles and the carbon nanotubes is within the above range, which can further improve the stability of the prepared window film, and synergistically improve the dispersibility and mechanical properties of the window film.

[0023] In a second aspect, the present application provides a method for preparing a heat-insulating window film, adopting the following technical solution: A method for preparing a heat-insulating window film includes the following steps: Mix PET resin, carbon nanotube composite, epoxy resin, and curing agent and stir evenly. After kneading, rough refining, and refining processes, cool down and extrude, filter, and after four-roll calendering, embossing, and warm refining, cool and shape, trim the edges and wind up to obtain a barrier layer. Then, successively laminate the protective layer, barrier layer, pressure-sensitive adhesive layer, and release film layer to prepare the heat-insulating window film.

[0024] In summary, the present application includes at least one of the following beneficial technical effects: 1. In the present application, a carbon nanotube composite component is added to the system. The carbon nanotube composite component is prepared from carbon nanotubes, polylactic acid, and poly(butylene adipate terephthalate). Carboxylated carbon nanotubes are a component with a unique nanostructure, having good mechanical properties and mechanical strength, capable of absorbing and dissipating infrared rays, thereby blocking infrared rays and playing a good heat-insulating role. Polylactic acid is a rigid polymer, and poly(butylene adipate terephthalate) has good elasticity and excellent biodegradability, and can further combine with polylactic acid to obtain a composite material with good mechanical properties, making the prepared heat-insulating film have good heat-insulating performance and mechanical strength. 2. The modified carbon nanotubes are prepared from carboxylated carbon nanotubes and polyethyleneimine. Polyethyleneimine has a three-dimensional dendritic structure and is a flexible polymer rich in primary and secondary amine groups. After combining with carboxylated carbon nanotubes, it can further improve the dispersion performance of carboxylated carbon nanotubes in the system. At the same time, it can further combine with epoxy resin to form a stable system, further enhancing the comprehensive performance of the prepared heat-insulating film. 3. Composite nanoparticles are also added to the system. Titanium dioxide is loaded on silica by a hydrothermal method, significantly improving the agglomeration phenomenon of silica, so as to enhance the anti-corrosion performance and self-cleaning performance of the system. Then, it is modified with fluoroalkylsilane, hydrolyzing and cross-linking in the system to form a solid film and an additive with self-healing performance, obtaining a system with hydrophobic properties and further enhancing the overall stability of the system. Specific embodiments

[0025] The following further elaborates on the present application with reference to examples: Description of raw materials: All raw materials in the examples can be obtained commercially; the curing agent is diethylenetriamine (CAS No.: 111-40-0).

[0026] Example 1 Prepare modified carbon nanotubes: Mix 1.45 g of polyethyleneimine (CAS No.: 9002-98-6) with 500 g of deionized water to obtain a polyethyleneimine solution. Add 7.27 g of carboxylated carbon nanotubes (CAS No.: 308068-56-6) to the polyethyleneimine solution to obtain a carbon nanotube dispersion. Condense and reflux the carbon nanotube dispersion in an oil bath at 120 °C for 12 h, then perform vacuum filtration, and then wash it repeatedly with deionized water 5 times. Freeze-dry it in a vacuum freeze dryer at -20 °C for 18 h to obtain modified carbon nanotubes.

[0027] Prepare carbon nanotube composites: Mix 29.35 g of polylactic acid (CAS No.: 26023-30-3), 8.39 g of poly(butylene adipate-co-terephthalate) (CAS No.: 55231-08-8) with 2.26 g of modified carbon nanotubes, and stir under vacuum conditions in a water bath at 25 °C for 2 h to obtain a reactant. Then volatilize the solvent of the reactant in a fume hood, send it into a twin-screw extruder for melting and extrusion, and then perform injection molding in an injection molding machine and grind to obtain carbon nanotube composites.

[0028] Prepare composite nanoparticles: Mix 60 g of titanium sulfate with 900 g of deionized water, then add 6 g of nano-titanium dioxide powder, stir in an environment at 25 °C, and simultaneously add ammonia water for hydrolysis until the pH of the system is 7.5 to obtain a precipitate. Filter the precipitate and wash it with ethanol. Subsequently, add the precipitate to 500 g of deionized water, and then add nitric acid with a mass fraction of 20 wt% until the pH of the system is 2 to prepare a silica composite sol. Dry it in an environment at 45 °C and then calcine it at 500 °C for 2 h to obtain silica composite titanium dioxide; mix 90 g of absolute ethanol, 90 g of toluene with 6 g of perfluorooctyltriethoxysilane, adjust the pH of the system to 9 using ammonia water, then add 18 g of the prepared silica composite titanium dioxide, perform ultrasonic dispersion, centrifuge at a speed of 8000 rpm for 10 min, wash it, and dry it at 65 °C for 8 h to obtain composite nanoparticles.

[0029] Prepare heat-insulating window films: The acrylate pressure-sensitive adhesive is coated on the surface of the release paper, left to age at 55°C, and dried to obtain a pressure-sensitive adhesive layer and a release film layer; 350 g of PET resin (CAS No.: 25038-59-9), 18 g of carbon nanotube composite, 80 g of epoxy resin, 9 g of composite nanoparticles and 30 g of curing agent are mixed and stirred evenly, and then subjected to kneading, rough refining and refining processes. After cooling, it is extruded, and after four-roll calendering, embossing and warming, it is cooled and shaped, and then trimmed and wound. After unwinding and corona treatment, a barrier layer is obtained. A polyester film is stacked on the surface of the barrier layer to form a protective layer. The barrier layer is laminated with the pressure-sensitive adhesive layer, so that the protective layer, the barrier layer, the pressure-sensitive adhesive layer and the release film layer are sequentially laminated to the rubber pressure roller and the cooling roller to perform multi-layer lamination of the coated release paper. After winding, corona treatment is carried out, and it is dried at 80°C to obtain a heat-insulating window film.

[0030] Example 2 Prepare modified carbon nanotubes: 4.36 g of polyethyleneimine is mixed with 500 g of deionized water to obtain a polyethyleneimine solution. 10.91 g of carboxylated carbon nanotubes is added to the polyethyleneimine solution to obtain a carbon nanotube dispersion. The carbon nanotube dispersion is placed in an oil bath at 120°C, condensed and refluxed for 12 h, vacuum filtered, and then repeatedly washed 5 times with deionized water. It is freeze-dried in a vacuum freeze dryer at -20°C for 18 h to obtain modified carbon nanotubes.

[0031] Prepare carbon nanotube composites: 28.99 g of polylactic acid, 8.28 g of polybutylene adipate terephthalate and 2.73 g of modified carbon nanotubes are mixed, and then stirred under vacuum conditions in a water bath at 25°C for 2 h to obtain a reactant. Then the reactant is volatilized of the solvent in a fume hood, fed into a twin-screw extruder for melting and extrusion, and injection molded in an injection molding machine, and then ground to obtain carbon nanotube composites.

[0032] Prepare composite nanoparticles: Mix 60 g of titanium sulfate with 900 g of deionized water, then add 6 g of nano-titanium dioxide powder, stir in an environment at 25 °C, and simultaneously add ammonia water for hydrolysis until the pH of the system is 7.5 to obtain a precipitate. Filter the precipitate and wash it with ethanol. Subsequently, add the precipitate to 500 g of deionized water, and then add nitric acid with a mass fraction of 20 wt% until the pH of the system is 2 to prepare a silica composite sol. After drying in an environment at 45 °C, calcine it at a temperature of 500 °C for 2 h to obtain silica composite titanium dioxide; mix 90 g of absolute ethanol, 90 g of toluene, and 6 g of perfluorooctyltriethoxysilane, adjust the pH of the system to 9 using ammonia water, then add 18 g of the prepared silica composite titanium dioxide, after ultrasonic dispersion, centrifuge at a speed of 8000 rpm for 10 min, wash it, and dry it at a temperature of 65 °C for 8 h to obtain composite nanoparticles.

[0033] Prepare a heat-insulating window film: Coat an acrylate pressure-sensitive adhesive on the surface of a release paper, let it stand and cure in an environment at 55 °C, and obtain a pressure-sensitive adhesive layer and a release film layer after drying; mix 450 g of PET resin, 22 g of carbon nanotube composite, 110 g of epoxy resin, 8.8 g of composite nanoparticles, and 50 g of a curing agent, stir evenly, go through the processes of internal mixing, rough mixing, and refining, cool down and then extrude, go through four-roll calendering, embossing, and warming, cool and shape, then trim the edges and wind it up, go through unwinding and corona treatment to obtain a barrier layer, stack a polyester film on the surface of the barrier layer to form a protective layer, bond the barrier layer and the pressure-sensitive adhesive layer, so that the protective layer, the barrier layer, the pressure-sensitive adhesive layer, and the release film layer are sequentially stacked at a rubber pressure roller and a cooling roller to perform multi-layer lamination on the coated release paper, wind it up and perform corona treatment, and dry it in an environment at 80 °C to obtain a heat-insulating window film.

[0034] Example 3 Prepare modified carbon nanotubes: Mix 2.73 g of polyethyleneimine with 500 g of deionized water to obtain a polyethyleneimine solution, add 9.09 g of carboxylated carbon nanotubes to the polyethyleneimine solution to obtain a carbon nanotube dispersion, reflux the carbon nanotube dispersion in an oil bath environment at 120 °C for 12 h, perform vacuum filtration, then wash it repeatedly with deionized water 5 times, and freeze-dry it at a temperature of -20 °C in a vacuum freeze dryer for 18 h to obtain modified carbon nanotubes.

[0035] Prepare a carbon nanotube composite: After mixing 29.17 g of polylactic acid, 8.33 g of poly(butylene adipate terephthalate), and 2.5 g of carbon nanotubes, stirring was carried out under a water bath condition at 25°C and under a vacuum condition for 2 h to obtain a reactant. Then, the solvent was evaporated from the reactant in a fume hood and fed into a twin-screw extruder for melting and extrusion. After injection molding in an injection molding machine, it was ground to obtain a carbon nanotube composite.

[0036] Preparation of composite nanoparticles: Mix 60 g of titanium sulfate with 900 g of deionized water, then add 6 g of nano-titanium dioxide powder, stir in an environment at 25°C, and simultaneously add ammonia water for hydrolysis until the pH of the system is 7.5 to obtain a precipitate. After filtering the precipitate, it was washed with ethanol. Subsequently, the precipitate was added to 500 g of deionized water, and then nitric acid with a mass fraction of 20 wt% was added until the pH of the system was 2 to prepare a silica composite sol. After drying in an environment at 45°C, it was calcined at a temperature of 500°C for 2 h to obtain silica composite titanium dioxide; after mixing 90 g of absolute ethanol, 90 g of toluene, and 6 g of perfluorooctyltriethoxysilane, the pH of the system was adjusted to 9 using ammonia water, and then 18 g of the prepared silica composite titanium dioxide was added. After ultrasonic dispersion, it was centrifuged at a speed of 8000 rpm for 10 min. After washing, it was dried at a temperature of 65°C for 8 h to obtain composite nanoparticles.

[0037] Preparation of heat-insulating window film: Coat acrylate pressure-sensitive adhesive on the surface of the release paper, and let it stand and mature in an environment at 55°C. After drying, a pressure-sensitive adhesive layer and a release film layer are obtained; after mixing 400 g of PET resin, 20 g of carbon nanotube composite, 90 g of epoxy resin, 9 g of composite nanoparticles, and 40 g of curing agent and stirring evenly, through the processes of internal mixing, rough mixing, and refining, after cooling, it is extruded. After four-roll calendering, embossing, and warming, it is cooled and shaped. Subsequently, trimming and winding are carried out. After unwinding and corona treatment, a barrier layer is obtained. A polyester film is stacked on the surface of the barrier layer to form a protective layer. The barrier layer is laminated with the pressure-sensitive adhesive layer, so that the protective layer, barrier layer, pressure-sensitive adhesive layer, and release film layer are sequentially laminated to the rubber pressure roller and the cooling roller to perform multi-layer lamination of the coated release paper. After winding, corona treatment is carried out, and it is dried in an environment at 80°C to obtain a heat-insulating window film.

[0038] Example 4 Example 4 is based on Example 3. In the preparation of modified carbon nanotubes in Example 4, 0.91 g of polyethyleneimine and 9.09 g of carboxylated carbon nanotubes were used.

[0039] Example 5 Example 5 Based on Example 3, when preparing the modified carbon nanotubes in Example 5, 4.55 g of polyethyleneimine and 9.09 g of carboxylated carbon nanotubes were used.

[0040] Example 6 Example 6 Based on Example 3, when preparing the carbon nanotube composite in Example 6, 29.79 g of polylactic acid, 8.51 g of poly(butylene adipate terephthalate), and 2.26 g of modified carbon nanotubes were used.

[0041] Example 7 Example 7 Based on Example 3, when preparing the carbon nanotube composite in Example 7, 28.57 g of polylactic acid, 8.16 g of poly(butylene adipate terephthalate), and 3.27 g of modified carbon nanotubes were used.

[0042] Example 8 Example 8 Based on Example 3, when preparing the carbon nanotube composite in Example 8, the modified carbon nanotubes were replaced with unmodified ordinary carbon nanotubes.

[0043] Example 9 Example 9 Based on Example 3, 6 g of composite nanoparticles were added in Example 9, and the rest was made up with PET resin.

[0044] Example 10 Example 10 Based on Example 3, 12 g of composite nanoparticles were added in Example 10.

[0045] Example 11 Example 11 Based on Example 3, in Example 11, the composite nanoparticles were replaced with silica composite titanium dioxide without perfluorooctyltriethoxysilane treatment.

[0046] Example 12 Example 12 Based on Example 3, the composite nanoparticles in Example 12 were prepared by mixing nano-silica and nano-titanium dioxide in a mass ratio of 1:1.

[0047] Example 13 Example 13 Based on Example 3, 60 g of epoxy resin was used in Example 13.

[0048] Example 14 Example 14 Based on Example 3, 120 g of epoxy resin was used in Example 14.

[0049] Comparative Example 1 Comparative Example 1 Based on Example 3, in Comparative Example 1, the carbon nanotube composite was replaced with ordinary carbon nanotubes.

[0050] Comparative Example 2 Taking Example 3 as the reference, in Comparative Example 2, the composite nanoparticles were replaced with an equal amount of PET resin.

[0051] Performance detection test The following performance tests were carried out on the samples of Examples 1-14 and Comparative Examples 1-2: (1) Heat insulation performance test Taking "QC_T 1170-2022 Functional Films for Automotive Glass" as the detection standard, the heat insulation performance of the samples was tested. Each sample was tested 3 times, and the average value was taken, and the test results were filled in Table 1.

[0052] (2) Anti-puncture performance test Taking "QC_1171-2022 Automotive Paint Protection Film" as the detection standard, the anti-puncture performance of the samples was tested. Each sample was tested three times, and the average value was taken, and the test results were filled in Table 1.

[0053] (3) Hydrothermal aging performance test After the samples were aged for 72 h in an environment with a temperature of 60 °C and a humidity of 80%, the infrared barrier performance test was carried out again. Each sample was tested 3 times, and the test results were filled in Table 1.

[0054] Table 1 Performance test results of the samples of Examples 1-14 and Comparative Examples 1-2 Combined with Table 1, it can be seen that the infrared barrier rates of Examples 1-3 are all 92% and above, indicating that the heat insulation window film prepared in this application has good heat insulation performance; the anti-puncture strengths of Examples 1-3 are all 202 N and above, indicating that the heat insulation window film prepared in this application has good strength, and the infrared barrier rates of Examples 1-3 after hydrothermal aging are all 87% and above, indicating that the heat insulation window film prepared in this application has good hydrothermal resistance.

[0055] In Examples 4 and 5, when preparing the modified carbon nanotubes, the mass ratios between polyethyleneimine and carbon nanotubes are not within the scope defined in this application. When the content of polyethyleneimine is too small, it is difficult to further modify the surface of carbon nanotubes, and the dispersion of carbon nanotubes in the system is difficult to be further improved, resulting in agglomeration in the system and affecting the overall stability of the system; when the content of polyethyleneimine is too large, the polyethyleneimine coating on the surface of carbon nanotubes is too thick, and the molecular interaction between the polyethyleneimines of adjacent carbon nanotubes will also cause the carbon nanotubes to agglomerate, affecting the overall stability of the system. Therefore, the performances of Examples 4 and 5 have both decreased.

[0056] In Examples 6 and 7 during the preparation of the carbon nanotube composite, the mass ratios among polylactic acid, poly(butylene adipate terephthalate), and the modified carbon nanotubes are not within the scope defined in this application. When the content of the modified carbon nanotubes is too low, it is difficult to further improve the overall mechanical properties of the system. Moreover, after the content of the carbon nanotubes decreases, it is difficult to further improve the overall heat insulation performance of the system, and it is also difficult to synergistically improve the overall performance of the system with the composite nanoparticles. When the content of the modified carbon nanotubes is too high, the excessive modified carbon nanotubes will agglomerate in the system, making it difficult to disperse evenly, and it will also affect the overall comprehensive performance of the system. Therefore, the performances of Examples 6 and 7 both decline.

[0057] In Example 8, the modified carbon nanotubes are replaced with ordinary unmodified carbon nanotubes. The unmodified carbon nanotubes agglomerate in the system and are difficult to disperse evenly in the system. Moreover, without polyethyleneimine modification, it is difficult to further combine with epoxy resin. Therefore, the comprehensive performance declines.

[0058] In Examples 9 and 10, the mass ratios between the composite nanoparticles and the carbon nanotube composite are not within the scope defined in this application. When the content of the composite nanoparticles is too low, the nano-components in the system decrease, making it difficult to compound and synergistically reinforce the resin system with the modified carbon nanotubes, which affects the strength of the system. At the same time, it is also difficult to further improve the heat insulation effect of the system, and the hydrophobic property also declines. When the content of the composite nanoparticles is too high, excessive nano-materials agglomerate in the system, affecting the overall stability of the system. Therefore, the performances of Examples 9 and 10 both decline.

[0059] In Example 11, silica composite titanium dioxide is not treated with perfluorooctyltriethoxysilane. The untreated system is difficult to further improve the overall hydrophobic property of the system. Therefore, the water resistance of Example 11 declines.

[0060] In Example 12, only nano-silica and nano-titanium dioxide are physically mixed to obtain composite nanoparticles. The composite nanoparticles obtained only by physical mixing are difficult to further combine, resulting in a decrease in stability, and they agglomerate in the system, affecting the overall stability of the system. Therefore, the performances of Example 12 all decline.

[0061] In Examples 13 and 14, the mass ratios between the epoxy resin and the carbon nanotube composite are not within the scope defined in this application. When the content of the epoxy resin is too high or too low, it is difficult to form a stable binding effect with the carbon nanotube composite, thereby affecting the overall performance of the system. Therefore, the comprehensive performances of Examples 13 and 14 both decline.

[0062] In Comparative Example 1, the carbon nanotube composite was replaced with ordinary carbon nanotubes. Since the modified carbon nanotubes agglomerated in the system and the overall stability of the system decreased, the comprehensive performance of Comparative Example 1 decreased.

[0063] In Comparative Example 2, no composite nanoparticles were added, making it difficult to synergistically improve the overall comprehensive performance of the system with the carbon nanotube composite. At the same time, the water resistance also decreased. Therefore, the comprehensive performance of Comparative Example 2 decreased.

[0064] This specific embodiment is only an interpretation of the present application and does not limit the present application. Through the above description, relevant staff can make various changes and modifications completely within the scope not deviating from the technical idea of this application. The technical scope of this application is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A thermal insulation window film, characterized in that: It comprises a protective layer, a barrier layer, a pressure-sensitive adhesive layer and a release film layer. The barrier layer comprises PET resin, a carbon nanotube composite, epoxy resin, composite nanoparticles and a curing agent; the carbon nanotube composite comprises modified carbon nanotubes, polylactic acid and polybutylene terephthalate-adipate.

2. The thermal insulation window film according to claim 1, characterized in that: The modified carbon nanotubes include carboxylated carbon nanotubes and polyethyleneimine.

3. The thermal insulation window film according to claim 2, characterized in that: The modified carbon nanotubes are prepared by the following method: Polyethyleneimine is mixed with water to obtain a polyethyleneimine solution, carboxylated carbon nanotubes are added to the polyethyleneimine solution to obtain a carbon nanotube dispersion, and the carbon nanotube dispersion is condensed and refluxed in an oil bath environment, vacuum filtered, washed and dried to obtain modified carbon nanotubes.

4. The thermal insulation window film according to claim 1, characterized in that: The carbon nanotube composite is prepared in the following manner: The polylactic acid, polybutylene terephthalate-adipate and modified carbon nanotubes are mixed, stirred in a water bath to obtain a reactant, and then melted, extruded and injection molded to obtain a carbon nanotube composite.

5. The heat-insulating window film according to claim 4, characterized in that: The mass ratio of the polylactic acid, polybutylene terephthalate-adipate and modified carbon nanotubes is 3.5:1:(0.27-0.33).

6. The thermal insulation window film according to claim 1, characterized in that: The mass ratio between the carbon nanotube composite and the epoxy resin is 1:(4-5).

7. The thermal insulation window film according to claim 1, characterized in that: The composite nanoparticles include silicon dioxide, titanium dioxide and fluoroalkyl silane.

8. The heat-insulating window film according to claim 7, characterized in that: The composite nanoparticles are prepared by the following method: Titanium sulfate is mixed with water, nano titanium dioxide powder is added, stirred and ammonia water is added for hydrolysis to obtain a precipitate, the precipitate is filtered and washed, then the precipitate is dispersed in water, nitric acid is added to obtain a silica composite sol, and the sol is dried and calcined to obtain silica composite titanium dioxide; anhydrous ethanol, toluene and fluoroalkyl silane are mixed, and silica composite titanium dioxide is added, ultrasonic dispersion is performed, centrifugal washing is performed, and drying is performed to obtain composite nanoparticles.

9. The heat-insulating window film according to claim 8, characterized in that: The mass ratio between the composite nanoparticles and the carbon nanotube composite is (1.5-1.4):

1.

10. A method for preparing the thermal insulation window film according to any one of claims 1 to 9, characterized in that: The steps include: PET resin, carbon nanotube composite, epoxy resin and curing agent are mixed and stirred evenly, and then subjected to the processes of internal mixing, rough mixing and refining, extruded after cooling, filtered, cooled and shaped after four-roll calendering, embossing and warm mixing, trimmed and rolled to obtain a barrier layer. The protective layer, barrier layer, pressure-sensitive adhesive layer and release film layer are compounded in sequence to prepare a heat-insulating window film.

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