Composite flexible heat insulation film and preparation process thereof

Abstract

The invention provides a composite flexible heat insulation film and a preparation process thereof, and belongs to the technical field of heat insulation materials. Comprising a precursor polyester film and an anti-ultraviolet heat-insulating coating, and the precursor polyester film comprises the following raw materials: polyethylene terephthalate particles, a modified flexibilizer, an antioxidant and a lubricant. The ethylene-octylene copolymer and itaconic anhydride are subjected to a grafting reaction under the initiation of dicumyl peroxide, itaconic anhydride is introduced into the ethylene-octylene copolymer to modify the ethylene-octylene copolymer, so that the limit of the ethylene-octylene copolymer is remarkably improved, and the modified toughening agent is prepared; and when the modified toughening agent and the polyethylene terephthalate are subjected to melt blending, the compatibility between the ethylene-octylene copolymer and a polyethylene terephthalate matrix can be remarkably improved, so that the flexibility of the polyethylene terephthalate is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of heat insulation materials, and particularly relates to a composite flexible heat insulation film and a preparation process thereof. Background Art

[0002] A heat insulation film is a functional film that selectively reflects and absorbs sunlight. It is usually composed of a coating and a polyester film treated by a process. Due to its heat insulation, safety, decoration and other characteristics, it shows excellent performance in energy conservation, heat insulation, ultraviolet protection, etc., making it widely used in the construction field. When the heat insulation film is used for building exterior walls or building glass, it can effectively reduce energy consumption, improve comfort and reduce ultraviolet damage.

[0003] Polyethylene terephthalate (PET) is a crystalline polyester. It has characteristics such as wear resistance, good insulation, good chemical stability, high strength and good gas barrier properties. However, due to the presence of rigid benzene rings in the molecular chain of PET material, the molecular chain movement is difficult, resulting in poor flexibility. In the prior art, using an elastomer to toughen and modify the polyester can improve its flexibility. However, the PET material has polar groups, making it highly polar, resulting in poor compatibility with the elastomer in terms of bonding, thus affecting the toughening and modification effect of the elastomer on the PET matrix.

[0004] Ytterbium (Yb), as a rare earth element, has unique optical properties. After doping it into the tin dioxide lattice, it can significantly enhance the infrared radiation absorption ability of the material. By absorbing rather than transmitting or reflecting infrared light, it can effectively block the transfer of heat energy. And lanthanum hexaboride nanomaterials have good shielding rates in the strong near-infrared light region of 760 - 1500 nm and can become good heat insulation materials. However, since both of them are nanomaterials, they have a large specific surface area and an extremely high proportion of surface atoms, resulting in a significant increase in surface energy. In the coating, they tend to combine with other particles through adsorption or chemical bonding to reduce the surface energy, thus causing agglomeration and further affecting the heat insulation performance of the coating.

[0005] Based on this, it is necessary to propose a composite flexible heat insulation film and a preparation process thereof that can improve the compatibility between the elastomer and the heat insulation filler. Summary of the Invention

[0006] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a composite flexible heat insulation film and a preparation process thereof.

[0007] A preparation process of a composite flexible heat insulation film includes the following steps: S1: Melting and blending the dried ethylene-octene copolymer and itaconic anhydride with diisopropylbenzene peroxide, a crosslinking inhibitor and an antioxidant, and then extruding and pelletizing to obtain a modified toughening agent; S2: dissolving 2-mercaptobenzoxazole and triethylamine in tetrahydrofuran, and then adding 3,4,5-trifluorobenzoyl chloride to react to obtain an anti-ultraviolet additive; S3: After dissolving L-glutamic acid, adding the pretreated ytterbium-doped tin dioxide to react to obtain surface-modified ytterbium-doped tin dioxide, then dissolving 1-butyl-3-methylimidazolium tetrafluoroborate in anhydrous ethanol, adding the pretreated nano lanthanum hexaboride to modify it, and obtaining modified nano lanthanum hexaboride; S4: After dissolving polyvinylidene fluoride, add silica aerogel, the above-mentioned anti-UV additives, surface-modified ytterbium-doped tin dioxide and modified nano lanthanum hexaboride to prepare an anti-UV thermal insulation coating, then mix the polyethylene terephthalate particles with the above-mentioned modified toughening agent to prepare a precursor polyester film, and finally coat the anti-UV thermal insulation coating on the surface of the precursor polyester film to obtain a composite flexible thermal insulation film.

[0008] Furthermore, S1 specifically includes the following steps: S1.1: The ethylene-octene copolymer particles are vacuum dried at 60-80°C for 4-6 hours, and the itaconic anhydride is dried at 40-50°C for 1-2 hours; S1.2: adding the dried ethylene-octene copolymer, the dried itaconic anhydride, dicumyl peroxide, a crosslinking inhibitor and an antioxidant into a high-speed mixer, and mixing for 10-20 minutes to obtain a blended material; S1.3: Add the above blended materials into a twin-screw extruder, set the feeding section temperature to 160-170°C, the melting section temperature to 180-190°C, the mixing reaction section temperature to 190-200°C, the die temperature to 180-190°C, the screw speed to 80-100rpm, melt reaction for 10-15min, and then extrude and granulate to obtain a modified toughening agent.

[0009] Furthermore, S2 specifically includes the following steps: S2.1: Add 2-mercaptobenzoxazole and triethylamine into tetrahydrofuran, stir and dissolve thoroughly to obtain a mixed solution; S2.2: In an ice-water bath, add 3,4,5-trifluorobenzoyl chloride to the mixed solution, stir and react for 2.5-3.5 hours, extract with ethyl acetate, wash with water, dry and rotary evaporate, and separate by column chromatography with an eluent to obtain an anti-ultraviolet additive, wherein the eluent is a mixture of petroleum ether and ethyl acetate in a volume ratio of (11-13):1.

[0010] Furthermore, S3 specifically includes the following steps: S3.1: ultrasonically clean the ytterbium-doped tin dioxide with 5% dilute hydrochloric acid for 20-30 minutes, then wash with deionized water until neutral, and dry to obtain pretreated ytterbium-doped tin dioxide; S3.2: dissolve L-glutamic acid in deionized water at a solid-liquid ratio of 1 g: (30-40) mL, add 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride, N-hydroxysuccinimide and 0.1 mol / L hydrochloric acid solution to adjust the pH to 3-3.5, then add the above-mentioned pretreated ytterbium-doped tin dioxide at a solid-liquid ratio of 1 g: (20-30) mL, heat and stir at 60-80°C for 5-6 hours, centrifuge, wash and vacuum dry to obtain surface-modified ytterbium-doped tin dioxide; S3.3: The nano-lanthanum hexaboride powder is ultrasonically cleaned with a 0.1 mol / L nitric acid solution for 20-30 min, then washed with deionized water until neutral, and dried to obtain pretreated nano-lanthanum hexaboride; S3.4: Dissolve 1-butyl-3-methylimidazolium tetrafluoroborate in anhydrous ethanol at a solid-liquid ratio of 1g: (8-10)mL, then add the above-mentioned pretreated nano-lanthanum hexaboride at a solid-liquid ratio of 1g: (20-30)mL, stir at 60-70°C for 3-4h, centrifuge, wash and vacuum dry to obtain modified nano-lanthanum hexaboride.

[0011] Furthermore, S4 specifically includes the following steps: S4.1: Add 25-35 parts by mass of polyvinylidene fluoride to 70-80 parts by mass of dimethylacetamide, stir thoroughly to dissolve, then add 6-8 parts by mass of silica aerogel, 3-5 parts by mass of the anti-ultraviolet additive obtained in step S2.2, 2-3 parts by mass of the surface-modified ytterbium-doped tin dioxide obtained in step S3.2 and 1-2 parts by mass of the modified nano lanthanum hexaboride obtained in step S3.4, stir thoroughly to mix, and obtain an anti-ultraviolet thermal insulation coating; S4.2: After the polyethylene terephthalate particles are dried, they are mixed evenly with the modified toughening agent, antioxidant and lubricant prepared in step S1.3, and then added to a twin-screw extruder for melt extrusion to form an amorphous polyester thick sheet on a cooling roller. After cooling, the amorphous polyester sheet is subjected to biaxial stretching, heat setting, and cooling to obtain a precursor polyester film; S4.3: The anti-ultraviolet heat-insulating coating is uniformly coated on the surface of the precursor polyester film, and after drying and curing, an anti-ultraviolet heat-insulating coating is formed to obtain a composite flexible heat-insulating film.

[0012] Furthermore, the blended material includes, by mass: 90-100 parts of ethylene-octene copolymer, 3-5 parts of itaconic anhydride, 0.2-0.6 parts of diisopropylbenzene peroxide, 1-2 parts of a crosslinking inhibitor and 0.1-0.5 parts of an antioxidant; wherein the crosslinking inhibitor is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and the antioxidant is Irganox1010.

[0013] Further, the solid-liquid ratio of 2-mercaptobenzoxazole to tetrahydrofuran is 1 g:(20 - 30) mL, the molar ratio of triethylamine to 2-mercaptobenzoxazole is (1.4 - 1.6):1, and the molar ratio of 3,4,5-trifluorobenzoyl chloride to 2-mercaptobenzoxazole is (1.2 - 1.3):1.

[0014] Further, the mass ratio of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxysuccinimide to L-glutamic acid is (1.5 - 1.7):1:(120 - 130).

[0015] Further, by mass, the raw material composition of the precursor polyester film is: 50 - 60 parts of polyethylene terephthalate particles, 4 - 6 parts of a modified toughening agent, 0.5 - 1 part of an antioxidant, and 0.4 - 0.6 part of a lubricant; wherein, the antioxidant is any one of antioxidant 1010 and antioxidant 1076, and the lubricant is any one of paraffin and ethylene bisoleamide.

[0016] A composite flexible heat-insulating film is prepared by the preparation process of a composite flexible heat-insulating film described in any one of the above.

[0017] Compared with the prior art, the present invention has at least the following beneficial effects: 1. In the present invention, ethylene-octene copolymer and itaconic anhydride are subjected to a graft reaction under the initiation of dicumyl peroxide, introducing itaconic anhydride into the ethylene-octene copolymer for modification, significantly improving the limit of the ethylene-octene copolymer to form a modified toughening agent. When the modified toughening agent is melt-blended with polyethylene terephthalate, the anhydride groups introduced by the modified toughening agent can react with the hydroxyl or carboxylic acid end groups of polyethylene terephthalate to achieve covalent bond connection, thereby significantly improving the compatibility between the ethylene-octene copolymer and the polyethylene terephthalate matrix, and further helping to improve the flexibility of polyethylene terephthalate.

[0018] 2. In the present invention, after dissolving 2-mercaptobenzoxazole and triethylamine in tetrahydrofuran, 3,4,5-trifluorobenzoyl chloride is added, enabling the mercapto group in 2-mercaptobenzoxazole to react with the carbonyl carbon of 3,4,5-trifluorobenzoyl chloride to form a thioester bond, obtaining an anti-ultraviolet additive with a benzoxazole and aromatic conjugate structure. The benzoxazole conjugate system can convert the absorbed ultraviolet light into other forms of energy dissipation. After adding this anti-ultraviolet additive to polyvinylidene fluoride to form a coating and coating it on the surface of the precursor polyester film, due to the introduction of fluorine atoms with low surface energy in the molecular structure, when the coating contacts the air, the molecules will accumulate near the surface, thereby protecting the interior from ultraviolet damage and achieving the effect of improving the anti-ultraviolet performance of the film.

[0019] 3. In the present invention, through the reaction of the carboxylic acid group of L-glutamic acid with the hydroxyl groups on the surface of ytterbium-doped tin dioxide, amino groups are introduced onto the surface of ytterbium-doped tin dioxide, forming hydrogen bonds with the fluorine atoms in the chain segments of the polyvinylidene fluoride matrix, promoting the molecular-level dispersion of the two phases. Thus, the dispersibility of ytterbium-doped tin dioxide in the polyvinylidene fluoride matrix can be effectively improved. And 1-butyl-3-methylimidazolium tetrafluoroborate is adsorbed on the surface of lanthanum hexaboride nanoparticles through electrostatic attraction to form a monolayer coating. After the surface modification of lanthanum hexaboride nanoparticles, the tetrafluoroborate anion and the C-F chain segments of polyvinylidene fluoride interact through fluorine-fluorine dipole interactions, significantly reducing the interfacial energy between the two phases and promoting the molecular-level binding of lanthanum hexaboride nanoparticles and the polyvinylidene fluoride matrix, thereby achieving the effect of improving the dispersibility of lanthanum hexaboride nanoparticles. In addition, when the surface-modified ytterbium-doped tin dioxide and the modified lanthanum hexaboride are compounded, the two can synergistically improve the heat insulation performance of the prepared coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings incorporated herein and constituting a part of the specification illustrate embodiments of the present disclosure and, together with the specification, are further used to explain the principles of the present disclosure and enable those skilled in the relevant art to implement and use the present disclosure.

[0021] Figure 1 It is the surface morphology diagram of the composite flexible heat insulation film prepared in Example 1 of the present invention.

[0022] Figure 2 It is the surface morphology diagram of the composite flexible heat insulation film prepared in Comparative Example 3 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] The following describes in detail a composite flexible heat insulation film and its preparation process provided by the present invention in conjunction with the drawings and specific embodiments. Example 1

[0024] A preparation process of a composite flexible heat insulation film includes the following steps: S1: Vacuum-dry ethylene-octene copolymer particles at 60 °C for 4 h, and dry itaconic anhydride at 40 °C for 1 h. Then, add 90 parts by mass of the dried ethylene-octene copolymer, 3 parts by mass of the dried itaconic anhydride, 0.2 parts by mass of diisopropylbenzene peroxide, 1 part by mass of pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and 0.1 part by mass of Irganox1010 into a high-speed mixer, mix for 10 min to obtain a blend material. Finally, add the blend material into a twin-screw extruder, set the feeding section temperature at 160 °C, the melting section temperature at 180 °C, the mixing reaction section temperature at 190 °C, the die head temperature at 180 °C, and the screw speed at 80 rpm, melt and react for 10 min, and then extrude and pelletize to obtain a modified toughening agent; S2: Add 2-mercaptobenzoxazole and triethylamine into tetrahydrofuran, stir well until dissolved to obtain a mixed solution. Among them, the solid-liquid ratio of 2-mercaptobenzoxazole to tetrahydrofuran is 1 g: 20 mL, and the molar ratio of triethylamine to 2-mercaptobenzoxazole is 1.4: 1. Then, under the condition of an ice-water bath, add 3,4,5-trifluorobenzoyl chloride to the mixed solution, stir and react for 2.5 h. After extraction with ethyl acetate, washing with water, drying and rotary evaporation, column chromatography separation is carried out with an eluent to obtain an anti-ultraviolet additive. Among them, the molar ratio of 3,4,5-trifluorobenzoyl chloride to 2-mercaptobenzoxazole is 1.2: 1, and the eluent is composed of petroleum ether and ethyl acetate mixed in a volume ratio of 11: 1; S3: Ultrasonically clean ytterbium-doped tin dioxide with 5% dilute hydrochloric acid for 20 min, then wash it with deionized water until neutral, and dry it to obtain pretreated ytterbium-doped tin dioxide. Then, dissolve L-glutamic acid in deionized water according to a solid-liquid ratio of 1 g: 30 mL, add 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxysuccinimide and 0.1 mol / L hydrochloric acid solution to adjust the pH to 3, and then add pretreated ytterbium-doped tin dioxide according to a solid-liquid ratio of 1 g: 20 mL. Heat and stir at 60 °C for 5 h, and after centrifugal separation, washing and vacuum drying, surface-modified ytterbium-doped tin dioxide is obtained. Among them, the mass ratio of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxysuccinimide to L-glutamic acid is 1.5: 1: 120. Subsequently, ultrasonically clean nano lanthanum hexaboride powder with 0.1 mol / L nitric acid solution for 20 min, then wash it with deionized water until neutral, and dry it to obtain pretreated nano lanthanum hexaboride. Finally, dissolve 1-butyl-3-methylimidazolium tetrafluoroborate in absolute ethanol according to a solid-liquid ratio of 1 g: 8 mL, and then add pretreated nano lanthanum hexaboride according to a solid-liquid ratio of 1 g: 20 mL. After stirring at 60 °C for 3 h, after centrifugation, washing and vacuum drying, modified nano lanthanum hexaboride is obtained; S4: Add 25 parts by mass of polyvinylidene fluoride into 70 parts by mass of dimethylacetamide, stir well until dissolved, and then add 6 parts by mass of silica aerogel, 3 parts by mass of the anti-ultraviolet additive prepared in step S2, 2 parts by mass of the surface-modified ytterbium-doped tin dioxide prepared in step S3 and 1 part by mass of the modified nano lanthanum hexaboride prepared in step S3, stir well and mix to obtain an anti-ultraviolet heat-insulating coating for standby. Then, dry 50 parts by mass of polyethylene terephthalate particles, mix them evenly with 4 parts by mass of the modified toughening agent prepared in step S1, 0.5 part by mass of antioxidant 1010 and 0.4 part by mass of paraffin wax, add them into a twin-screw extruder for melt extrusion, form an amorphous polyester thick sheet on a cooling roll, and after cooling, carry out biaxial stretching and then heat setting. After cooling, a precursor polyester film is obtained. Finally, uniformly coat the anti-ultraviolet heat-insulating coating on the surface of the above precursor polyester film, and after drying and curing, an anti-ultraviolet heat-insulating coating is formed to obtain a composite flexible heat-insulating film. Example 2

[0025] A preparation process of a composite flexible thermal insulation film comprises the following steps: S1: The ethylene-octene copolymer particles were vacuum dried at 70°C for 5h, and itaconic anhydride was dried at 45°C for 1.5h, and then 95 parts by mass of the dried ethylene-octene copolymer, 4 parts by mass of dried itaconic anhydride, 0.4 parts by mass of diisopropylbenzene peroxide, 1.5 parts by mass of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and 0.4 parts by mass of Irganox1010 were added to a high-speed mixer, and mixed for 15min to obtain a blended material. Finally, the blended material was added to a twin-screw extruder, and the feeding section temperature was set to 165°C, the melting section temperature was set to 185°C, the mixing reaction section temperature was set to 195°C, the head temperature was set to 185°C, the screw speed was set to 90rpm, the melt reaction was carried out for 12.5min, and then extruded and granulated to obtain a modified toughening agent; S2: Add 2-mercaptobenzoxazole and triethylamine to tetrahydrofuran, stir and dissolve to obtain a mixed solution, wherein the solid-liquid ratio of 2-mercaptobenzoxazole to tetrahydrofuran is 1 g:25 mL, and the molar ratio of triethylamine to 2-mercaptobenzoxazole is 1.5:1. Then, add 3,4,5-trifluorobenzoyl chloride to the mixed solution under ice-water bath conditions, stir and react for 3 hours, extract with ethyl acetate, wash with water, dry and rotary evaporate, and separate by column chromatography with an eluent to obtain an anti-ultraviolet additive, wherein the molar ratio of 3,4,5-trifluorobenzoyl chloride to 2-mercaptobenzoxazole is 1.25:1, and the eluent is a mixture of petroleum ether and ethyl acetate in a volume ratio of 12:1; S3: Ultrasonically clean ytterbium-doped tin dioxide with 5% dilute hydrochloric acid for 25 min, then wash it with deionized water until neutral. After drying, obtain pretreated ytterbium-doped tin dioxide. Then dissolve L-glutamic acid in deionized water at a solid-liquid ratio of 1 g: 35 mL, add 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxysuccinimide and 0.1 mol / L hydrochloric acid solution to adjust the pH to 3.2, and then add pretreated ytterbium-doped tin dioxide at a solid-liquid ratio of 1 g: 25 mL. Heat and stir at 70 °C for 5.5 h, and after centrifugal separation, washing and vacuum drying, obtain surface-modified ytterbium-doped tin dioxide. Among them, the mass ratio of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxysuccinimide to L-glutamic acid is 1.6: 1: 125. Subsequently, ultrasonically clean lanthanum hexaboride nanopowder with 0.1 mol / L nitric acid solution for 25 min, then wash it with deionized water until neutral. After drying, obtain pretreated lanthanum hexaboride nanopowder. Finally, dissolve 1-butyl-3-methylimidazolium tetrafluoroborate in absolute ethanol at a solid-liquid ratio of 1 g: 9 mL, and then add pretreated lanthanum hexaboride nanopowder at a solid-liquid ratio of 1 g: 25 mL. After stirring at 65 °C for 3.5 h, through centrifugation, washing and vacuum drying, obtain modified lanthanum hexaboride nanopowder; S4: Add 30 parts by mass of polyvinylidene fluoride to 75 parts by mass of dimethylacetamide, stir and dissolve thoroughly, then add 7 parts by mass of silica aerogel, 4 parts by mass of the anti-ultraviolet additive prepared in step S2, 2.5 parts by mass of the surface-modified ytterbium-doped tin dioxide prepared in step S3 and 1.5 parts by mass of the modified lanthanum hexaboride nanopowder prepared in step S3, stir and mix thoroughly to obtain an anti-ultraviolet heat-insulating coating for standby. Then dry 50 - 60 parts by mass of polyethylene terephthalate particles, mix them evenly with 5 parts by mass of the modified toughening agent prepared in step S1, 0.8 part by mass of antioxidant 1010 and 0.5 part by mass of paraffin, add them into a twin-screw extruder for melt extrusion, form an amorphous polyester thick sheet on a cooling roller, and after cooling, through biaxial stretching and then heat setting, and after cooling, obtain a precursor polyester film. Finally, evenly coat the anti-ultraviolet heat-insulating coating on the surface of the above-mentioned precursor polyester film, and after drying and curing, form an anti-ultraviolet heat-insulating coating to obtain a composite flexible heat-insulating film. Example 3

[0026] A preparation process of a composite flexible heat-insulating film, comprising the following steps: S1: The ethylene-octene copolymer particles were vacuum dried at 80°C for 6h, and itaconic anhydride was dried at 50°C for 2h, and then 100 parts by mass of the dried ethylene-octene copolymer, 5 parts by mass of the dried itaconic anhydride, 0.6 parts by mass of diisopropylbenzene peroxide, 2 parts by mass of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and 0.5 parts by mass of Irganox1010 were added to a high-speed mixer, and mixed for 20 minutes to obtain a blended material. Finally, the blended material was added to a twin-screw extruder, and the feeding section temperature was set to 170°C, the melting section temperature was set to 190°C, the mixing reaction section temperature was set to 200°C, the head temperature was set to 190°C, the screw speed was set to 100rpm, the melt reaction was carried out for 15 minutes, and then extruded and granulated to obtain a modified toughening agent; S2: Add 2-mercaptobenzoxazole and triethylamine to tetrahydrofuran, stir and dissolve to obtain a mixed solution, wherein the solid-liquid ratio of 2-mercaptobenzoxazole to tetrahydrofuran is 1 g:30 mL, and the molar ratio of triethylamine to 2-mercaptobenzoxazole is 1.6:1. Then, add 3,4,5-trifluorobenzoyl chloride to the mixed solution under ice-water bath conditions, stir and react for 3.5 hours, extract with ethyl acetate, wash with water, dry and rotary evaporate, and separate by column chromatography with an eluent to obtain an anti-ultraviolet additive, wherein the molar ratio of 3,4,5-trifluorobenzoyl chloride to 2-mercaptobenzoxazole is 1.3:1, and the eluent is a mixture of petroleum ether and ethyl acetate in a volume ratio of 13:1; S3: The ytterbium-doped tin dioxide was ultrasonically cleaned with 5% dilute hydrochloric acid for 30 minutes, and then washed with deionized water until neutral, and dried to obtain pretreated ytterbium-doped tin dioxide, and then L-glutamic acid was dissolved in deionized water at a solid-liquid ratio of 1g:40mL, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxysuccinimide and 0.1mol / L hydrochloric acid solution were added to adjust the pH to 3.5, and then the pretreated ytterbium-doped tin dioxide was added at a solid-liquid ratio of 1g:30mL, and the reaction was heated and stirred at 80°C for 6h, and the surface-modified ytterbium-doped tin dioxide was obtained after centrifugal separation, washing and vacuum drying, wherein 1 -ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride, N-hydroxysuccinimide and L-glutamic acid in a mass ratio of 1.7:1:130. Subsequently, the nano-lanthanum hexaboride powder was ultrasonically cleaned with a 0.1 mol / L nitric acid solution for 30 min, then washed with deionized water until neutral, and dried to obtain pretreated nano-lanthanum hexaboride. Finally, 1-butyl-3-methylimidazole tetrafluoroborate was dissolved in anhydrous ethanol at a solid-liquid ratio of 1g:10mL, and then the pretreated nano-lanthanum hexaboride was added at a solid-liquid ratio of 1g:30mL. After stirring at 70°C for 4h, the modified nano-lanthanum hexaboride was obtained by centrifugation, washing and vacuum drying. S4: Add 35 parts by mass of polyvinylidene fluoride to 80 parts by mass of dimethylacetamide, stir well to dissolve, then add 8 parts by mass of silica aerogel, 5 parts by mass of the ultraviolet-resistant additive prepared in step S2, 3 parts by mass of surface-modified ytterbium-doped tin dioxide prepared in step S3, and 2 parts by mass of modified nano-lanthanum hexaboride prepared in step S3, stir well and mix to obtain an ultraviolet-resistant heat-insulating coating for standby. Then, after drying 60 parts by mass of polyethylene terephthalate particles, mix them evenly with 6 parts by mass of the modified toughening agent prepared in step S1, 1 part by mass of antioxidant 1076, and 0.6 part by mass of ethylene bisoleamide, add them to a twin-screw extruder for melt extrusion, form an amorphous polyester thick sheet on a cooling roller, after cooling, perform biaxial stretching, then heat setting, and after cooling, obtain a precursor polyester film. Finally, evenly coat the ultraviolet-resistant heat-insulating coating on the surface of the above-mentioned precursor polyester film, and after drying and curing, form an ultraviolet-resistant heat-insulating coating to obtain a composite flexible heat-insulating film.

[0027] Comparative Example 1 The difference between this Comparative Example 1 and Example 1 is that step S1 is removed, and the modified toughening agent in step S4 is replaced with an equal amount of ethylene-octene copolymer.

[0028] Comparative Example 2 The difference between this Comparative Example 2 and Example 1 is that step S2 is removed, and the ultraviolet-resistant additive in step S4 is removed.

[0029] Comparative Example 3 The difference between this Comparative Example 3 and Example 1 is that step S3 is removed, and the surface-modified ytterbium-doped tin dioxide in step S4 is replaced with an equal amount of ytterbium-doped tin dioxide, and the modified nano-lanthanum hexaboride is replaced with an equal amount of nano-lanthanum hexaboride.

[0030] Comparative Example 4 The difference between this Comparative Example 4 and Example 1 is that the surface-modified ytterbium-doped tin dioxide in step S4 is replaced with an equal amount of modified nano-lanthanum hexaboride.

[0031] Comparative Example 5 The difference between this Comparative Example 5 and Example 1 is that the modified nano-lanthanum hexaboride in step S4 is replaced with an equal amount of surface-modified ytterbium-doped tin dioxide.

[0032] Test Example Test 1: Test the elongation at break of the precursor polyester films prepared in Examples 1 - 3 and Comparative Example 1, and the results are shown in Table 1.

[0033] Table 1: Elongation at break of the precursor polyester film Elongation at break (%) Example 1 158 Example 2 159 Example 3 157 Comparative Example 1 122 As shown in Table 1, after the ethylene-octene copolymer was not modified in Comparative Example 1 and directly melt-blended with polyethylene terephthalate particles to prepare the precursor polyester film, the elongation at break of the precursor polyester film was lower than that in Example 1, indicating that after the ethylene-octene copolymer was modified with itaconic anhydride, the compatibility between it and the polyethylene terephthalate matrix could be effectively improved, thereby improving the flexibility of the precursor polyester film.

[0034] Test 2: Use an ultraviolet spectrophotometer to measure the ultraviolet cut-off rate of the composite flexible thermal insulation films prepared in Examples 1-3 and Comparative Example 2 in the range of 280-400 nm, and measure the UV aging yellowing index of each composite flexible thermal insulation film at 120 kwh / m 2 . The results are shown in Table 2.

[0035] Table 2: Ultraviolet cut-off rate and yellowing index of composite flexible thermal insulation films UV cut-off rate (%) Yellowing index Example 1 98.8 1.4 Example 2 99.3 1.3 Example 3 99.4 1.3 Comparative Example 2 92.5 2.8 As shown in Table 2, after the anti-ultraviolet additive was not added in Comparative Example 2, the ultraviolet cut-off rate and yellowing index of the prepared composite flexible thermal insulation film were both lower than those in Example 1. It can be seen that after 2-mercaptobenzoxazole and triethylamine were dissolved in tetrahydrofuran and then 3,4,5-trifluorobenzoyl chloride was added, the mercapto group in 2-mercaptobenzoxazole reacted with the carbonyl carbon of 3,4,5-trifluorobenzoyl chloride to form a thioester bond, obtaining an anti-ultraviolet additive with a benzoxazole and aromatic conjugate structure. After adding the anti-ultraviolet additive to polyvinylidene fluoride to form a coating and coating it on the surface of the precursor polyester film, the anti-ultraviolet performance of the film can be improved.

[0036] Test 3: Use a scanning electron microscope to analyze the surface morphology of the composite flexible thermal insulation films prepared in Example 1 and Comparative Example 3. The SEM images are as shown in Figure 1 and Figure 2 .

[0037] From Figure 1 and Figure 2 , it can be seen that there are no obvious agglomerated particles on the surface of the composite flexible thermal insulation film prepared in Example 1, while there are many agglomerates on the surface of the composite flexible thermal insulation film prepared in Comparative Example 1. It can be seen that using L-glutamic acid to modify the surface of ytterbium-doped tin dioxide and using 1-butyl-3-methylimidazolium tetrafluoroborate to modify the surface of nano-lanthanum hexaboride can significantly improve the dispersibility of ytterbium-doped tin dioxide and nano-lanthanum hexaboride.

[0038] Test 4: The heat insulation performance of the composite flexible heat insulation film was tested using a heat insulation test device. The composite flexible heat insulation films prepared in Examples 1-3 and Comparative Examples 4-5 were laid flat in the middle of the device, and the film was closely attached to the inner wall of the device to block the gas flow in the upper and lower spaces. The top of the closed space above the composite flexible heat insulation film was simulated with a tungsten lamp for sunlight. After irradiating for 30 minutes, the room temperature in the closed space below the composite flexible heat insulation film was measured, and the temperature difference from the initial temperature of the lower closed space was calculated. The results are shown in Table 3.

[0039] Table 3: Heat insulation performance of the composite flexible heat insulation film Temperature difference (°C) Example 1 9.7 Example 2 9.6 Example 3 9.1 Comparative Example 4 17.4 Comparative Example 5 16.2 As shown in Table 3, when only modified nano-lanthanum hexaboride and only surface-modified ytterbium-doped tin dioxide were used to prepare the anti-ultraviolet heat insulation coating in Comparative Example 4 and Comparative Example 5, after the composite flexible heat insulation film was irradiated with a tungsten lamp for 30 minutes, the temperature differences were higher than those in Example 1. Thus, it can be seen that the compounding of surface-modified ytterbium-doped tin dioxide and modified lanthanum hexaboride can synergistically improve the heat insulation performance of the prepared anti-ultraviolet heat insulation coating, and further improve the heat insulation performance of the composite flexible heat insulation film.

[0040] The above embodiments are only illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A preparation process of a composite flexible heat-insulating film, characterized in that, The steps include: S1: Melting and blending the dried ethylene-octene copolymer and itaconic anhydride with dicumyl peroxide, a crosslinking inhibitor and an antioxidant, and then extruding and granulating to obtain a modified toughening agent; S2: dissolving 2-mercaptobenzoxazole and triethylamine in tetrahydrofuran, and then adding 3,4,5-trifluorobenzoyl chloride to react to obtain an anti-ultraviolet additive; S3: After dissolving L-glutamic acid, adding the pretreated ytterbium-doped tin dioxide to react to obtain surface-modified ytterbium-doped tin dioxide, then dissolving 1-butyl-3-methylimidazolium tetrafluoroborate in anhydrous ethanol, adding the pretreated nano lanthanum hexaboride to modify it, and obtaining modified nano lanthanum hexaboride; S4: After dissolving polyvinylidene fluoride, add silica aerogel, the above-mentioned anti-UV additives, surface-modified ytterbium-doped tin dioxide and modified nano lanthanum hexaboride to prepare an anti-UV thermal insulation coating, then mix the polyethylene terephthalate particles with the above-mentioned modified toughening agent to prepare a precursor polyester film, and finally coat the anti-UV thermal insulation coating on the surface of the precursor polyester film to obtain a composite flexible thermal insulation film.

2. The preparation process of a composite flexible heat-insulating film according to claim 1, characterized in that S1 specifically includes the following steps: S1.1: The ethylene-octene copolymer particles are vacuum dried at 60-80°C for 4-6 hours, and the itaconic anhydride is dried at 40-50°C for 1-2 hours; S1.2: adding the dried ethylene-octene copolymer, the dried itaconic anhydride, dicumyl peroxide, a crosslinking inhibitor and an antioxidant into a high-speed mixer, and mixing for 10-20 minutes to obtain a blended material; S1.3: Add the above blended materials into a twin-screw extruder, set the feeding section temperature to 160-170°C, the melting section temperature to 180-190°C, the mixing reaction section temperature to 190-200°C, the die temperature to 180-190°C, the screw speed to 80-100rpm, melt reaction for 10-15min, and then extrude and granulate to obtain a modified toughening agent.

3. The preparation process of a composite flexible heat insulation film according to claim 2, characterized in that, S2 specifically includes the following steps: S2.1: Add 2-mercaptobenzoxazole and triethylamine into tetrahydrofuran, stir and dissolve thoroughly to obtain a mixed solution; S2.2: In an ice-water bath, add 3,4,5-trifluorobenzoyl chloride to the mixed solution, stir and react for 2.5-3.5 hours, extract with ethyl acetate, wash with water, dry and rotary evaporate, and separate by column chromatography with an eluent to obtain an anti-ultraviolet additive, wherein the eluent is a mixture of petroleum ether and ethyl acetate in a volume ratio of (11-13):

1.

4. The preparation process of a composite flexible heat-insulating film according to claim 3, characterized in that, S3 specifically includes the following steps: S3.1: ultrasonically clean the ytterbium-doped tin dioxide with 5% dilute hydrochloric acid for 20-30 minutes, then wash with deionized water until neutral, and dry to obtain pretreated ytterbium-doped tin dioxide; S3.2: Dissolve L-glutamic acid in deionized water at a solid-liquid ratio of 1 g : (30 - 40) mL, add 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxysuccinimide and 0.1 mol / L hydrochloric acid solution to adjust the pH to 3 - 3.5, then add the above-mentioned pretreated ytterbium-doped tin dioxide at a solid-liquid ratio of 1 g : (20 - 30) mL, heat and stir at 60 - 80 °C for 5 - 6 h, and obtain surface-modified ytterbium-doped tin dioxide through centrifugal separation, washing and vacuum drying; S3.3: Ultrasonically clean the nano lanthanum hexaboride powder with 0.1 mol / L nitric acid solution for 20 - 30 min, then wash it with deionized water until neutral, and obtain pretreated nano lanthanum hexaboride after drying; S3.4: Dissolve 1-butyl-3-methylimidazolium tetrafluoroborate in absolute ethanol at a solid-liquid ratio of 1 g : (8 - 10) mL, then add the above-mentioned pretreated nano lanthanum hexaboride at a solid-liquid ratio of 1 g : (20 - 30) mL, stir at 60 - 70 °C for 3 - 4 h, and obtain modified nano lanthanum hexaboride through centrifugation, washing and vacuum drying.

5. The preparation process of a composite flexible heat insulation film according to claim 4, characterized in that, S4 specifically includes the following steps: S4.1: Add 25 - 35 parts by mass of polyvinylidene fluoride to 70 - 80 parts by mass of dimethylacetamide, stir and dissolve fully, then add 6 - 8 parts by mass of silica aerogel, 3 - 5 parts by mass of the ultraviolet-resistant additive prepared in step S2.2, 2 - 3 parts by mass of the surface-modified ytterbium-doped tin dioxide prepared in step S3.2 and 1 - 2 parts by mass of the modified nano lanthanum hexaboride prepared in step S3.4, and stir and mix fully to obtain an ultraviolet-resistant heat-insulating coating; S4.2: After drying the polyethylene terephthalate particles, mix them evenly with the modified toughening agent, antioxidant and lubricant prepared in step S1.3, then add them into a twin-screw extruder for melt extrusion, form an amorphous polyester thick sheet on a cooling roll, and after cooling, perform biaxial stretching and then heat setting, and obtain a precursor polyester film after cooling; S4.3: Uniformly coat the above-mentioned ultraviolet-resistant heat-insulating coating on the surface of the above-mentioned precursor polyester film, and form an ultraviolet-resistant heat-insulating coating after drying and curing to obtain a composite flexible heat-insulating film.

6. The preparation process of a composite flexible heat insulation film according to claim 2, characterized in that, By mass, the blend material includes: 90 - 100 parts of ethylene-octene copolymer, 3 - 5 parts of itaconic anhydride, 0.2 - 0.6 parts of diisopropylbenzene peroxide, 1 - 2 parts of crosslinking inhibitor and 0.1 - 0.5 parts of antioxidant; among them, the crosslinking inhibitor is pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and the antioxidant is Irganox1010.

7. The preparation process of a composite flexible heat-insulating film according to claim 3, characterized in that, The solid-liquid ratio of 2-mercaptobenzoxazole to tetrahydrofuran is 1 g : (20 - 30) mL, the molar ratio of triethylamine to 2-mercaptobenzoxazole is (1.4 - 1.6) : 1, and the molar ratio of 3,4,5-trifluorobenzoyl chloride to 2-mercaptobenzoxazole is (1.2 - 1.3) :

1.

8. The preparation process of a composite flexible heat-insulating film according to claim 4, characterized in that, The mass ratio of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride, N-hydroxysuccinimide to L-glutamic acid is (1.5 - 1.7) : 1 : (120 - 130).

9. The preparation process of a composite flexible heat-insulating film according to claim 5, characterized in that, By mass, the raw material composition of the precursor polyester film is: 50 - 60 parts of polyethylene terephthalate particles, 4 - 6 parts of a modified toughening agent, 0.5 - 1 part of an antioxidant, and 0.4 - 0.6 part of a lubricant; wherein, the antioxidant is any one of antioxidant 1010 and antioxidant 1076, and the lubricant is any one of paraffin wax and ethylene bisoleamide.

10. A composite flexible heat-insulating film, characterized in that, It is prepared by the preparation process of a composite flexible heat insulation film according to any one of claims 1 - 9.

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