A method for preparing a porous thermal insulation film and an automobile film using the same

Abstract

The application discloses a kind of porous heat insulation film preparation methods, comprising: step one, preparation PVDF-b-PTFE powder;Step two, PVDF-b-PTFE powder obtained in step 1 is added to the mixed solution of N, N-dimethylformamide and acetone, to obtain precursor spinning solution;Step three, barium titanate nanoparticles are added to the precursor spinning solution obtained in step two, to obtain BTO / PVDF-b-PTFE mixed solution;Step four, the BTO / PVDF-b-PTFE mixed solution obtained in step three is spun by electrospinning process to obtain porous heat insulation film;The porous heat insulation film prepared by electrospinning is BTO / PVDF-b-PTFE nanofiber heat insulation film with good durability, can effectively block infrared and ultraviolet light for a long time, significantly reduce indoor and in-car temperature.In the process of manufacturing and using, no harmful substances are released, raw materials are relatively easy to recycle and handle, it is an environment-friendly material with energy-saving effect, and can remain stable under extreme weather conditions, with strong stability.

Description

Technical Field

[0001] This invention relates to the field of heat insulation film preparation, specifically to a method for preparing a porous heat insulation film and an automotive film using the porous heat insulation film. Background Technology

[0002] The solar spectrum encompasses three main bands: first, the ultraviolet (200-400nm) band, accounting for 3% of sunlight energy; second, the visible light band (400-760nm), accounting for 44%; and finally, the infrared (760-2500nm) band, with an energy share as high as 53%, becoming the most significant part of sunlight. In the hot summer, sunlight is particularly intense. When sunlight penetrates glass into indoor or car interiors, the temperature rises sharply, significantly impacting the living environment and passenger experience. The infrared band, due to its large energy proportion, is the primary factor contributing to the increased temperature at the point of exposure. Currently, the main method relies on window tinting to block infrared rays and reduce the significant increase in interior temperature. However, the heat insulation effect of existing sun protection and heat insulation films is limited. They can only block some infrared rays and cannot block ultraviolet rays. Moreover, the heat insulation effect is not significant. Especially in extremely hot weather, the film may not be able to completely prevent the indoor temperature from rising. In addition, the poor quality and short lifespan of the film will cause problems such as aging, bubbling and peeling after long-term use. This will not only affect its sun protection and heat insulation effect, but may also affect its appearance. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method for preparing a porous heat insulation film that is reliable, has good heat insulation effect and can block ultraviolet rays, and an automotive film using the porous heat insulation film.

[0004] To solve the above-mentioned technical problems, the present invention provides a method for preparing a porous heat insulation film, comprising: Step 1: Prepare PVDF-b-PTFE powder; Step 2: Add the PVDF-b-PTFE powder obtained in Step 1 to an N,N-dimethylformamide solution, or a mixture of N,N-dimethylformamide and acetone, to obtain a precursor spinning solution. Step 3: Add barium titanate nanoparticles to the precursor spinning solution obtained in Step 2 to obtain a BTO / PVDF-b-PTFE mixture; Step 4: The BTO / PVDF-b-PTFE mixture obtained in Step 3 is spun into a porous heat insulation film by electrospinning.

[0005] Preferably, the preparation process of PVDF-b-PTFE powder in step 1 is as follows: A1. Add deionized water to the reactor and heat the reactor; A2. Add the initiator to the reactor and mix it evenly with a stirrer; A3. Add vinylidene fluoride monomer gas into the reactor and pressurize it by introducing tetrafluoroethylene monomer gas. A4. Continue the reaction until the solid content in the reactor reaches 15-25%, then stop the reaction and remove the latex-like PVDF-b-PTFE. A5. The latex-like PVDF-b-PTFE obtained above is naturally dried, and then ground by ball mill to obtain PVDF-b-PTFE powder.

[0006] Furthermore, the reactor is a 40-liter reactor; the weight of deionized water is 22.5 kg; the heating temperature of the reactor in step A1 is 80°C and maintained; the initiator added to the reactor is 100-200 g; in step A3, vinylidene fluoride monomer gas is added to the reactor to make the pressure inside the reactor reach 0.35 MPa; and then tetrafluoroethylene monomer gas is introduced until the pressure inside the reactor reaches 1.52 MPa.

[0007] Furthermore, the initiator is a nitroxide free radical initiator.

[0008] Based on the above, the nitroxide free radical initiator includes one of the following: ammonium persulfate, benzoyl peroxide, benzoyl bromide peroxide, benzoyl peroxide, phenylacetyl peroxide, n-butyl peracrylate, acryloyl acrylate peroxide, toluene peroxide, tert-butylbenzene peroxide, hydrogenated benzene peroxide, tert-butyl peroxide, or N-methylpyrrolidone.

[0009] Furthermore, in step A3, the weight ratio of vinylidene fluoride monomer gas and tetrafluoroethylene monomer gas introduced into the reactor is 0.8 to 1.2:1.

[0010] Preferably, the preparation process of the precursor spinning solution in step two is as follows: PVDF-b-PTFE powder is added to a mixed solvent of N,N-dimethylformamide and acetone, and stirred for 2-6 hours in a water bath at 50-80°C; wherein the volume ratio of N,N-dimethylformamide to acetone is 1:0-10.

[0011] Preferably, the preparation process of the BTO / PVDF-b-PTFE mixture in step three is as follows: barium titanate nanoparticles are mixed with the precursor spinning solution and stirred in a water bath at 40-70°C for 6-12 hours; wherein the mass ratio of barium titanate nanoparticles to the precursor spinning solution is 1:2-10.

[0012] Preferably, in step four, the electrostatic voltage of electrospinning is 20–80 kV, the receiving distance is 10–60 cm, the infusion rate is 20–1500 mL / h, the spinning temperature is 25–40 °C, and the relative humidity is 35%–65%.

[0013] An automotive film prepared using the porous heat insulation film preparation method of claim 1, characterized in that it comprises at least one layer of porous heat insulation film.

[0014] Compared with existing technologies, this invention has the following beneficial effects: The porous heat insulation film prepared by electrospinning, namely the BTO / PVDF-b-PTFE nanofiber heat insulation film, has excellent durability and can effectively block infrared and ultraviolet rays for a long time, significantly reducing indoor and vehicle interior temperatures. It exhibits a high solar reflectivity of 80-99.8% and a high-mid-infrared emissivity of 70-99.8%. The interior temperature of a car covered with the porous BTO / PVDF-b-PTFE heat insulation film can be reduced by more than 5-55°C compared to a commercial vehicle cover, and by more than 10-80°C compared to a model without fabric coverage.

[0015] This invention does not release harmful substances during manufacturing and use, and the raw materials are relatively easy to recycle and process. It is an energy-saving and environmentally friendly material that can remain stable under extreme climatic conditions and has strong stability.

[0016] Furthermore, the heat insulation film prepared by electrospinning in this invention is a nanofiber membrane, which has excellent properties such as high porosity, softness, bend resistance, and stretchability. The material has a porosity of 60-80%, a thickness of 0.1-10 mm, and a fiber diameter of 50-1000 nm. Detailed Implementation

[0017] The following description is intended to disclose the invention so that those skilled in the art can implement it. The preferred embodiments described below are merely examples, and other obvious modifications will be apparent to those skilled in the art. The basic principles of the invention defined in the following description can be used in other embodiments, modifications, improvements, equivalents, and other technical solutions that do not depart from the spirit and scope of the invention.

[0018] Example 1: A method for preparing a porous heat insulation film, comprising: Step 1: Preparation of PVDF-b-PTFE powder; The preparation process of PVDF-b-PTFE powder is as follows: A1. Add deionized water to the reactor and heat the reactor; A2. Add initiator to the reactor and mix evenly with a stirrer; A3. Add vinylidene fluoride monomer gas to the reactor and pressurize it by introducing tetrafluoroethylene monomer gas; A4. Continue the reaction until the solid content in the reactor reaches 15%, stop the reaction and remove the latex-like PVDF-b-PTFE; A5. Allow the latex-like PVDF-b-PTFE obtained above to dry naturally, and then grind it using a ball mill to obtain PVDF-b-PTFE powder.

[0019] Specifically, 22.5 kg of deionized water was added to a 40-liter reactor, and the reactor was heated to 80°C. 100 g of initiator was added, and the stirrer speed was set to 200 rpm to ensure uniform mixing. Vinylidene fluoride monomer gas was added to the reactor to bring the pressure inside to 0.35 MPa. Then, tetrafluoroethylene monomer gas was introduced to pressurize the reactor until the pressure reached 1.52 MPa. During this process, an additional 2500 g of deionized water could be added to accelerate dissolution and continue the reaction until the solid content reached 15%. The reaction was then stopped, and the latex was discharged from the reactor. After natural drying, it was ground in a ball mill to form PVDF-b-PTFE powder. The weight ratio of vinylidene fluoride monomer gas to tetrafluoroethylene monomer gas introduced into the reactor was 0.8:1.

[0020] The aforementioned initiator is a nitroxide free radical initiator, specifically one of the following: ammonium persulfate, benzoyl peroxide, benzoyl bromide peroxide, benzoyl peroxide, phenylacetyl peroxide, n-butyl peracrylate, acryloyl acrylate peroxide, toluene peroxide, tert-butylbenzene peroxide, hydrogen peroxide, tert-butyl peroxide, or N-methylpyrrolidone.

[0021] Step 2: Add the PVDF-b-PTFE powder obtained in Step 1 to a mixture of N,N-dimethylformamide and acetone to obtain a precursor spinning solution. Specifically, the preparation process of the precursor spinning solution is as follows: add the PVDF-b-PTFE powder to a mixed solvent of N,N-dimethylformamide and acetone, and stir for 6 hours in a 50°C water bath; wherein the volume ratio of N,N-dimethylformamide to acetone is 1:10. The acetone used accelerates dissolution.

[0022] Step 3: Add barium titanate nanoparticles to the precursor spinning solution obtained in Step 2 to obtain a BTO / PVDF-b-PTFE mixture. Specifically, the preparation process of the BTO / PVDF-b-PTFE mixture is as follows: mix the barium titanate nanoparticles with the precursor spinning solution and stir for 12 hours in a 40°C water bath. The mass ratio of barium titanate nanoparticles to the precursor spinning solution is 1:2.

[0023] Step 4: The BTO / PVDF-b-PTFE mixture obtained in Step 3 is spun into a porous heat insulation membrane using an electrospinning process. The electrospinning parameters are: electrostatic voltage 20kV, receiving distance 10cm, infusion rate 20mL / h, spinning temperature 25℃, and relative humidity 65%.

[0024] Example 2: A method for preparing a porous heat insulation film, comprising: Step 1: Preparation of PVDF-b-PTFE powder; The preparation process of PVDF-b-PTFE powder is as follows: A1. Add deionized water to the reactor and heat the reactor; A2. Add initiator to the reactor and mix evenly with a stirrer; A3. Add vinylidene fluoride monomer gas to the reactor and pressurize it by introducing tetrafluoroethylene monomer gas; A4. Continue the reaction until the solid content in the reactor reaches 25%, stop the reaction and remove the latex-like PVDF-b-PTFE; A5. Allow the latex-like PVDF-b-PTFE obtained above to dry naturally, and then grind it using a ball mill to obtain PVDF-b-PTFE powder.

[0025] Specifically, 22.5 kg of deionized water was added to a 40-liter reactor, and the reactor was heated to 80°C. 200 g of initiator was added, and the stirrer speed was set to 400 rpm to ensure uniform mixing. Vinylidene fluoride monomer gas was added to the reactor to bring the pressure inside to 0.35 MPa. Then, tetrafluoroethylene monomer gas was introduced to pressurize the reactor until the pressure reached 1.52 MPa. During this process, an additional 2500 g of deionized water could be added to accelerate dissolution and continue the reaction until the solid content reached 25%. The reaction was then stopped, and the latex was discharged from the reactor. After natural drying, it was ground in a ball mill to form PVDF-b-PTFE powder. The weight ratio of vinylidene fluoride monomer gas to tetrafluoroethylene monomer gas introduced into the reactor was 1.2:1.

[0026] The aforementioned initiator is a nitroxide free radical initiator, specifically one of the following: ammonium persulfate, benzoyl peroxide, benzoyl bromide peroxide, benzoyl peroxide, phenylacetyl peroxide, n-butyl peracrylate, acryloyl acrylate peroxide, toluene peroxide, tert-butylbenzene peroxide, hydrogen peroxide, tert-butyl peroxide, or N-methylpyrrolidone.

[0027] Step 2: Add the PVDF-b-PTFE powder obtained in Step 1 to a mixture of N,N-dimethylformamide and acetone to obtain a precursor spinning solution. Specifically, the preparation process of the precursor spinning solution is as follows: add the PVDF-b-PTFE powder to a mixed solvent of N,N-dimethylformamide and acetone, and stir for 2 hours in an 80°C water bath; wherein the volume ratio of N,N-dimethylformamide to acetone is 1:5.

[0028] Step 3: Add barium titanate nanoparticles to the precursor spinning solution obtained in Step 2 to obtain a BTO / PVDF-b-PTFE mixture. Specifically, the preparation process of the BTO / PVDF-b-PTFE mixture is as follows: mix the barium titanate nanoparticles with the precursor spinning solution and stir for 6 hours in a 70°C water bath. The mass ratio of barium titanate nanoparticles to the precursor spinning solution is 1:10.

[0029] Step 4: The BTO / PVDF-b-PTFE mixture obtained in Step 3 is spun into a porous heat insulation membrane using an electrospinning process. The electrospinning parameters are: electrostatic voltage 80kV, receiving distance 60cm, infusion rate 1500mL / h, spinning temperature 40℃, and relative humidity 35%.

[0030] Example 3: A method for preparing a porous heat insulation film, comprising: Step 1: Preparation of PVDF-b-PTFE powder; The preparation process of PVDF-b-PTFE powder is as follows: A1. Add deionized water to the reactor and heat the reactor; A2. Add initiator to the reactor and mix evenly with a stirrer; A3. Add vinylidene fluoride monomer gas to the reactor and pressurize it by introducing tetrafluoroethylene monomer gas; A4. Continue the reaction until the solid content in the reactor reaches 20%, stop the reaction and remove the latex-like PVDF-b-PTFE; A5. Allow the latex-like PVDF-b-PTFE obtained above to dry naturally, and then grind it using a ball mill to obtain PVDF-b-PTFE powder.

[0031] Specifically, 22.5 kg of deionized water was added to a 40-liter reactor, and the reactor was heated to 80°C. 150 g of initiator was added, and the stirrer speed was set to 300 rpm to ensure uniform mixing. Vinylidene fluoride monomer gas was added to the reactor to bring the pressure inside to 0.35 MPa. Then, tetrafluoroethylene monomer gas was introduced to pressurize the reactor until the pressure reached 1.52 MPa. During this process, an additional 2500 g of deionized water could be added to accelerate dissolution and continue the reaction until the solid content reached 20%. The reaction was then stopped, and the latex was discharged from the reactor. After natural drying, it was ground in a ball mill to form PVDF-b-PTFE powder. The weight ratio of vinylidene fluoride monomer gas to tetrafluoroethylene monomer gas introduced into the reactor was 1:1.

[0032] The aforementioned initiator is a nitroxide free radical initiator, specifically one of the following: ammonium persulfate, benzoyl peroxide, benzoyl bromide peroxide, benzoyl peroxide, phenylacetyl peroxide, n-butyl peracrylate, acryloyl acrylate peroxide, toluene peroxide, tert-butylbenzene peroxide, hydrogen peroxide, tert-butyl peroxide, or N-methylpyrrolidone.

[0033] Step 2: Add the PVDF-b-PTFE powder obtained in Step 1 to a mixture of N,N-dimethylformamide and acetone to obtain a precursor spinning solution. Specifically, the preparation process of the precursor spinning solution is as follows: add PVDF-b-PTFE powder to a mixed solvent of N,N-dimethylformamide and acetone, and stir for 4 hours in a water bath at 60°C; wherein the volume ratio of N,N-dimethylformamide to acetone is 1:1.

[0034] Step 3: Add barium titanate nanoparticles to the precursor spinning solution obtained in Step 2 to obtain a BTO / PVDF-b-PTFE mixture. Specifically, the preparation process of the BTO / PVDF-b-PTFE mixture is as follows: mix the barium titanate nanoparticles with the precursor spinning solution and stir for 8 hours in a 50°C water bath. The mass ratio of barium titanate nanoparticles to the precursor spinning solution is 1:6.

[0035] Step 4: The BTO / PVDF-b-PTFE mixture obtained in Step 3 is spun into a porous heat insulation membrane using an electrospinning process. The electrospinning parameters are: electrostatic voltage 50kV, receiving distance 40cm, infusion rate 700mL / h, spinning temperature 35℃, and relative humidity 50%.

[0036] Example 4: A method for preparing a porous heat insulation film, comprising: Step 1: Preparation of PVDF-b-PTFE powder; The preparation process of PVDF-b-PTFE powder is as follows: A1. Add deionized water to the reactor and heat the reactor; A2. Add initiator to the reactor and mix evenly with a stirrer; A3. Add vinylidene fluoride monomer gas to the reactor and pressurize it by introducing tetrafluoroethylene monomer gas; A4. Continue the reaction until the solid content in the reactor reaches 20%, stop the reaction and remove the latex-like PVDF-b-PTFE; A5. Allow the latex-like PVDF-b-PTFE obtained above to dry naturally, and then grind it using a ball mill to obtain PVDF-b-PTFE powder.

[0037] Specifically, 22.5 kg of deionized water was added to a 40-liter reactor, and the reactor was heated to 80°C. 200 g of initiator was added, and the stirrer speed was set to 400 rpm to ensure uniform mixing. Vinylidene fluoride monomer gas was added to the reactor to bring the pressure inside to 0.35 MPa. Then, tetrafluoroethylene monomer gas was introduced to pressurize the reactor until the pressure reached 1.52 MPa. During this process, an additional 2500 g of deionized water could be added to accelerate dissolution and continue the reaction until the solid content reached 20%. The reaction was then stopped, and the latex was discharged from the reactor. After natural drying, it was ground in a ball mill to form PVDF-b-PTFE powder. The weight ratio of vinylidene fluoride monomer gas to tetrafluoroethylene monomer gas introduced into the reactor was 1.2:1.

[0038] The aforementioned initiator is a nitroxide free radical initiator, specifically one of the following: ammonium persulfate, benzoyl peroxide, benzoyl bromide peroxide, benzoyl peroxide, phenylacetyl peroxide, n-butyl peracrylate, acryloyl acrylate peroxide, toluene peroxide, tert-butylbenzene peroxide, hydrogen peroxide, tert-butyl peroxide, or N-methylpyrrolidone.

[0039] Step 2: Add the PVDF-b-PTFE powder obtained in Step 1 to an N,N-dimethylformamide solution and stir for 6 hours in a 50°C water bath to obtain a precursor spinning solution.

[0040] Step 3: Add barium titanate nanoparticles to the precursor spinning solution obtained in Step 2 to obtain a BTO / PVDF-b-PTFE mixture. Specifically, the preparation process of the BTO / PVDF-b-PTFE mixture is as follows: mix the barium titanate nanoparticles with the precursor spinning solution and stir for 8 hours in a 70°C water bath. The mass ratio of barium titanate nanoparticles to the precursor spinning solution is 1:2.

[0041] Step 4: The BTO / PVDF-b-PTFE mixture obtained in Step 3 is spun into a porous heat insulation membrane using an electrospinning process. The electrospinning parameters are: electrostatic voltage 80kV, receiving distance 10cm, infusion rate 600mL / h, spinning temperature 25℃, and relative humidity 50%.

[0042] This invention utilizes electrospinning to prepare a porous heat-insulating film, a BTO / PVDF-b-PTFE nanofiber heat-insulating film, which exhibits excellent durability and can effectively block infrared and ultraviolet rays for extended periods, significantly reducing indoor and vehicle interior temperatures. It boasts a high solar reflectivity of 80-99.8% and a high-mid-infrared emissivity of 70-99.8%. The interior temperature of a car covered with this porous BTO / PVDF-b-PTFE heat-insulating film can be reduced by more than 5-55°C compared to a commercial vehicle covered with a cover, and by more than 10-80°C compared to a model without fabric coverage.

[0043] This invention does not release harmful substances during manufacturing and use, and the raw materials are relatively easy to recycle and process. It is an energy-saving and environmentally friendly material that can remain stable under extreme climatic conditions and has strong stability.

[0044] It is worth mentioning that the porous heat insulation film prepared by the porous heat insulation film preparation method can be used in automotive films. Specifically, the automotive film includes at least one layer of porous heat insulation film prepared by the porous heat insulation film preparation method.

[0045] Those skilled in the art will understand that the embodiments of the present invention shown in the above description are merely examples and do not limit the present invention. The objectives of the present invention have been fully and effectively achieved. The functions and structural principles of the present invention have been demonstrated and explained in the embodiments, and any variations or modifications may be made to the implementation of the present invention without departing from the stated principles.

Claims

1. A method for preparing a porous heat-insulating film, characterized in that, include: Step 1: Prepare PVDF-b-PTFE powder. The preparation process of the PVDF-b-PTFE powder is as follows: A1. Add deionized water to the reactor and heat the reactor. The reactor is a 40-liter reactor and the weight of the deionized water is 22.5 kg. The heating temperature of the reactor in step A1 is 80°C and maintained. A2. Add the initiator to the reactor and mix it evenly with a stirrer. The amount of initiator added to the reactor is 100-200 grams. A3. Add vinylidene fluoride monomer gas into the reactor and pressurize it by introducing tetrafluoroethylene monomer gas. Add vinylidene fluoride monomer gas into the reactor until the pressure inside the reactor reaches 0.35 MPa, and then introduce tetrafluoroethylene monomer gas until the pressure inside the reactor reaches 1.52 MPa. A4. Continue the reaction until the solid content in the reactor reaches 15-25%, then stop the reaction and discharge the latex-like PVDF-b-PTFE. A5. The latex-like PVDF-b-PTFE obtained above is naturally dried, and then ground by ball mill to obtain PVDF-b-PTFE powder. Step 2: Add the PVDF-b-PTFE powder obtained in Step 1 to a mixture of N,N-dimethylformamide solution and acetone, and stir for 2-6 hours in a water bath at 50-80°C to obtain a precursor spinning solution, wherein the volume ratio of N,N-dimethylformamide to acetone is 1:0-10. Step 3: Add barium titanate nanoparticles to the precursor spinning solution obtained in Step 2, and stir for 6 to 12 hours in a water bath at 40 to 70°C to obtain a BTO / PVDF-b-PTFE mixture, wherein the mass ratio of barium titanate nanoparticles to precursor spinning solution is 1:2 to 10. Step 4: The BTO / PVDF-b-PTFE mixture obtained in Step 3 is spun into a porous heat insulation film by electrospinning.

2. The method for preparing a porous heat-insulating film according to claim 1, characterized in that, The initiator is a nitroxide free radical initiator.

3. The method for preparing a porous heat-insulating film according to claim 2, characterized in that, The nitroxide radical initiator includes one of the following: ammonium persulfate, benzoyl peroxide, benzoyl bromide peroxide, benzoyl peroxide, phenylacetyl peroxide, n-butyl peroxide, acryloyl acrylate peroxide, toluene peroxide, tert-butylbenzene peroxide, hydrogenated benzene peroxide, tert-butyl peroxide, or N-methylpyrrolidone.

4. The method for preparing a porous heat-insulating film according to claim 1, characterized in that, In step A3, the weight ratio of vinylidene fluoride monomer gas and tetrafluoroethylene monomer gas introduced into the reactor is 0.8 to 1.2:

1.

5. The method for preparing a porous heat-insulating film according to claim 1, characterized in that, In step four, the electrostatic voltage for electrospinning is 20–80 kV, the receiving distance is 10–60 cm, the injection rate is 20–1500 mL / h, the spinning temperature is 25–40 °C, and the relative humidity is 35%–65%.

6. An automotive film prepared using the porous heat insulation film preparation method of claim 1, characterized in that, It includes at least one layer of porous heat insulation film.