Preparation method of heat-insulating PVB (polyvinyl butyral) resin powder and heat-insulating PVB film

Abstract

The invention discloses a preparation method of heat-insulating PVB (Polyvinyl Butyral) resin powder and a heat-insulating PVB film, and belongs to the technical field of PVB resin powder preparation. Comprising the following steps: S1, adding heat-insulating powder, sodium citrate and an auxiliary agent into a hydrochloric acid solution, fully stirring to obtain a heat-insulating powder suspension, ball-milling to obtain slurry, adjusting the pH value to be less than 1, and centrifuging to obtain a nano heat-insulating dispersion liquid; s2, fully reacting a PVA solution / n-butyraldehyde mixed solution with the nano heat-insulating dispersion liquid, washing, centrifuging and drying to obtain heat-insulating PVB resin powder; wherein the heat insulation powder is selected from rare earth element compounds. The PVB resin powder is used for preparing the heat-insulating PVB film. The infrared barrier rate of the PVB film in a low wave band and a high wave band can reach 98% or above, the full-wave-band infrared light barrier performance is remarkably improved, the light transmittance meets the standard of the heat-insulating PVB film, the haze is greatly reduced compared with a common heat-insulating film without a sodium citrate auxiliary, and the heat-insulating PVB film has excellent infrared shielding performance and optical performance.

Description

Technical Field

[0001] The invention relates to the technical field of PVB resin powder preparation, and in particular to a preparation method of heat-insulating PVB resin powder and a heat-insulating PVB film. Background Art

[0002] The chemical name of PVB is polyvinyl butyral, which is a condensation product of polyvinyl alcohol and butyraldehyde. It has high transparency, cold resistance and impact resistance. The intermediate film made of PVB resin powder is used to make the interlayer material of safety glass. The safety glass has good transparency and high impact strength, and is widely used in high-rise buildings, aviation and automobile fields. The PVB film prepared by extrusion casting of PVB resin powder itself has good light transmittance and impact resistance. In recent years, it has been widely used in high-rise building doors and windows and automobile glass. However, the heat insulation effect of PVB itself is not ideal, which can easily cause high temperatures indoors or in the car. In order to improve the heat insulation effect of glass doors and windows, the prior art usually uses nano metal oxides to modify the function of PVB film. Its heat insulation principle is to physically block and absorb infrared light in a specific wavelength range, effectively reducing the transfer of heat. For example, CN115894749 discloses “a method for synthesizing heat-insulating PVB powder”, CN104877582A discloses “a modified PVB resin powder and a preparation method thereof”, and CN106543927A discloses “a PVB film with heat-insulating properties and a preparation method thereof”.

[0003] However, the above prior art mainly has the following deficiencies:

[0004] (1) Nano thermal insulation particles tend to quickly precipitate and agglomerate in the solvent, and it is difficult to disperse them evenly when directly added to PVB resin powder. The PVB film prepared subsequently will have quality problems such as reduced optical properties and increased haze.

[0005] (2) Commonly used nano-metal oxides such as ITO, ATO, and AZO can only effectively shield near-infrared light with a wavelength greater than 1500-2000nm, but have poor infrared light blocking effects with a wavelength below 800nm ​​or above 2000nm. The overall infrared blocking rate is difficult to reach more than 95%, and the thermal insulation performance needs to be improved. Summary of the invention

[0006] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a method for preparing a heat-insulating PVB resin powder and a heat-insulating PVB film, so as to at least achieve the purpose of improving the heat-insulating performance and the light-transmitting performance.

[0007] The objective of the present invention is achieved through the following technical solutions:

[0008] A method for preparing heat-insulating PVB resin powder comprises the following steps:

[0009] S1. Add the insulation powder, sodium citrate and additives to the hydrochloric acid solution, stir well to obtain the insulation powder suspension, then ball mill to obtain the slurry, adjust the pH value of the slurry to less than 1 with hydrochloric acid and centrifuge to obtain the nano-insulation dispersion;

[0010] S2. The PVA solution / n-butyraldehyde mixture is fully reacted with the nano-insulation dispersion, and the insulating PVB resin powder is obtained after washing, centrifugation and drying;

[0011] The thermal insulation powder is selected from rare earth element compounds.

[0012] In the above scheme, the thermal insulation powder is first dispersed in a hydrochloric acid solution, and then subjected to ball milling and ultrasonic modification treatment to obtain a small-particle-size nano-thermal insulation dispersion. The small-particle-size nano-thermal insulation dispersion is then mixed with a PVA solution / n-butyraldehyde mixed solution through a tubular reactor. The small-particle-size thermal insulation powder acts as a nucleating agent to promote micelle nucleation, achieve a high polymerization rate and a narrow molecular weight distribution, and the synthesized PVB thermal insulation resin powder has good uniformity and high bulk density. The PVB film produced using the resin powder has high light transmittance, low haze, high infrared blocking rate, and good thermal insulation performance.

[0013] Furthermore, the functions of the relevant components in the above scheme are as follows:

[0014] The present invention selects rare earth element compounds as thermal insulation fillers, which can cooperate with physical blocking and localized surface plasma resonance effect (LSPR effect) to greatly improve the wavelength range of infrared light blocked. Sodium citrate is added to modify the rare earth thermal insulation dispersion to improve the dispersion uniformity of the thermal insulation powder, and participate in the synthesis process of PVB through a tubular reactor, wherein the thermal insulation powder acts as a nucleating agent to promote the rapid in-situ emulsion polymerization reaction of PVA and n-butyraldehyde, and can promote the rapid in-situ emulsion polymerization reaction of PVA and n-butyraldehyde, so that the acetal degree reaches a certain value in a short time, shortens the time for the precipitated resin powder to become sticky, and avoids uneven reaction caused by stickiness, thereby synthesizing a synthetic thermal insulation PVB resin powder with a narrow molecular weight distribution, small fluctuation of hydroxyl content, and good uniformity.

[0015] Preferably, in step S1, the average diameter of the particles in the nano thermal insulation dispersion is 20 to 50 nm.

[0016] Preferably, in step S1, the rare earth element compound is one or more of boron lanthanum compounds, cerium oxide, neodymium oxide, holmium oxide, ytterbium oxide, and scandium oxide.

[0017] Preferably, in step S1, the auxiliary agent is one or more of sodium dodecyl sulfate, sodium methyl nitrile sulfonate, and sodium methyl dimethylamine sulfonate.

[0018] Preferably, in step S1, the mass concentration of the hydrochloric acid solution is 0.5-1.5%.

[0019] Preferably, in step S1, the mass ratio of the thermal insulation powder, sodium citrate and the auxiliary agent is 1: (0.01-0.05):

[0020] (0.005-0.01); the mass ratio of the thermal insulation powder to the hydrochloric acid solution is 1:(20-50).

[0021] Preferably, in step S2, the preparation method of the PVA / n-butyraldehyde mixed solution is: take 100 parts by mass of PVA and 670-1330 parts by mass of pure water at room temperature, add them into a dissolving kettle, heat them to 90°C-98°C, stir them thoroughly to completely dissolve them into a PVA aqueous solution, filter them, cool them to 35°C-50°C, add 50-65 parts by mass of n-butyraldehyde, stir them at high speed,

[0022] After 10 to 40 minutes, a uniform PVA / n-butyraldehyde mixed solution is obtained.

[0023] Preferably, the specific steps of step S2 are: the PVA / n-butyraldehyde mixed solution and the nano-insulating dispersion are continuously introduced into a tubular reactor with heating and cooling functions through their respective pipelines at a mass ratio of 5:1 within 8-12 minutes, and all the materials are transferred to an aging kettle with an initial temperature of 30-40°C, and the stirring speed is set to 60-100r / min. After reacting for 1-2h, the temperature is increased to 50-65°C at a heating rate of 1°C / 5min. After continuing the reaction for 1-2h, all the materials are transferred to a washing kettle, and then washed with deionized water. After centrifugation and drying, powdered insulating PVB resin powder is obtained.

[0024] In addition, to achieve the above-mentioned purpose, the present invention also provides a method for preparing a thermal insulation PVB film, comprising dissolving an antioxidant and an ultraviolet absorber in a plasticizer, and mixing them evenly to prepare a mixed solution; and extruding the mixed solution and the thermal insulation PVB resin powder according to any one of claims 1 to 9 through a twin-screw extruder to obtain a thermal insulation PVB film.

[0025] In the present invention, the PVB film prepared by using PVB resin powder can have excellent heat insulation performance without adding additional heat insulation particles, so that the production process of the film is simpler and the problems of easy agglomeration and poor dispersion of the heat insulation particles are avoided.

[0026] Preferably, the mass ratio of the heat-insulating PVB resin powder, plasticizer, antioxidant and ultraviolet absorber is (70-75): (25-30): (0.15-0.35): (0.1-0.2).

[0027] Preferably, the plasticizer is one or more of phthalates, phosphates, dibasic fatty acid esters, and polyol esters;

[0028] Preferably, the antioxidant is one or more of 2,6-di-tert-butyl-4-methylphenol (BHT), pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate (antioxidant 1010), tris(2,4-di-tert-butylphenyl) phosphite, and dilauryl thiodipropionate;

[0029] Preferably, the ultraviolet absorber is one or more of UV-P, UVP-327, UV-5411, YASORBUV-2908, and UV-571.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. The present invention prepares a small-particle nano thermal insulation agent containing rare earth elements, and then evenly disperses the thermal insulation particles in a catalyst solution, and reacts with PVA / n-butyraldehyde through a tubular reactor, thereby preventing the thermal insulation particles from settling and agglomerating, making the thermal insulation dispersion system more stable, and the nano thermal insulation particles play a nucleation role, accelerating the in-situ emulsion polymerization of PVA and n-butyraldehyde, achieving a high polymerization rate and a narrow molecular weight distribution, and the synthesized PVB thermal insulation resin powder has good uniformity and high bulk density, thereby avoiding yellowing and an increase in yellow spots caused by uneven reaction.

[0032] 2. The nano rare earth thermal insulation particles introduced into the PVB resin powder of the present invention can resonate the light waves of 750-2500nm through the localized surface plasma resonance effect (LSPR effect), effectively shielding the infrared light in the low band of 700-800nm ​​and the high band of 2000-2500nm. The PVB film prepared with the resin powder has excellent near-infrared shielding performance without the need for additional thermal insulation additives. The infrared blocking rate in the low band and high band can reach more than 98%, and the transmittance is greater than 75% and the haze is less than 0.15%. DETAILED DESCRIPTION

[0033] Example 1

[0034] S1. Add 10g of rare earth cerium oxide powder, 0.1g of sodium citrate and 50mg of sodium methyldimethylamine sulfonate to 500g of 0.5% hydrochloric acid solution at 35℃, and stir for 1h to obtain a thermal insulation powder suspension. Use zirconium beads as ball milling beads, put the thermal insulation powder suspension into a ball mill for 1 hour, and then remove the ball milling beads to obtain a slurry. Rapidly adjust the pH value to less than 1 with hydrochloric acid, and treat the slurry in a centrifuge at a rotation speed of 1000rpm for 10min to obtain a nano thermal insulation dispersion with an average particle size of 20-50nm.

[0035] S2. At 35°C, 100g PVA and 900g deionized water are added to a dissolving kettle, stirred to completely dissolve, and then 58g n-butyraldehyde is added to the PVA solution, and stirred at high speed for 30min to obtain a PVA / n-butyraldehyde mixed solution; 1058g of the PVA / n-butyraldehyde mixed solution and the heat-insulating dispersion prepared in step S1 are mixed in a mass ratio of 100:20, and continuously enter a microreactor with heating and cooling functions through their respective pipelines within 12min, and all the materials are transferred to an aging kettle with a water bath temperature of 35°C, and the stirring speed is set to 60r / min. After reacting for 1h, the temperature is increased to 60°C at a heating rate of 1°C / 5min. After continuing the reaction for 1h, all the materials are transferred to a washing kettle, and then washed with deionized water. After centrifugation and drying, the heat-insulating PVB resin powder is obtained.

[0036] S3. Take 75 parts by mass of the heat-insulating PVB resin powder prepared in step S2, 25 parts by mass of phthalate plasticizer, 0.15 parts by mass of BHT and 0.1 parts by mass of UV-P, add them into a twin-screw extruder for melt plasticization, set the extrusion temperature to 160°C and the die temperature to 175°C, and obtain a heat-insulating PVB film by extrusion casting with a specification of 0.76mm.

[0037] Example 2

[0038] S1. Preparation of nano thermal insulation dispersion: add 10g rare earth neodymium oxide powder, 0.2g sodium citrate and 60mg sodium dodecyl sulfate to 500g hydrochloric acid solution with a mass concentration of 1.0% at 35°C, stir for 1h to obtain a thermal insulation powder suspension, put the thermal insulation powder suspension into a ball mill with zirconium beads as ball milling beads for 1 hour, then remove the ball milling beads to obtain a slurry, quickly adjust the pH value to less than 1 with hydrochloric acid, and treat the slurry in a centrifuge at a rotation speed of 1000rpm for 20min to obtain a nano thermal insulation dispersion with an average particle size of 20-50nm.

[0039] S2. At 35°C, 100g PVA and 1000g deionized water were added to a dissolving kettle, stirred to completely dissolve, and then 61g n-butyraldehyde was added to the PVA solution, and stirred at high speed for 30min to obtain a PVA / n-butyraldehyde mixed solution; 1161g of the above-mentioned PVA / n-butyraldehyde mixed solution and the dispersion prepared in step S1 were mixed in a mass ratio of 100:20, and continuously entered into a microreactor with heating and cooling functions through their respective pipelines within 12min, and all the materials were transferred to an aging kettle with a water bath temperature of 35°C, and the stirring speed was set to 60r / min. After reacting for 1h, the temperature was raised to 60°C at a heating rate of 1°C / 5min. After continuing the reaction for 1h, all the materials were transferred to a washing kettle, and then washed with deionized water. After centrifugation and drying, the insulating PVB resin powder was obtained.

[0040] S3. Take 75 parts by mass of the heat-insulating PVB resin powder prepared in step S2, 25 parts by mass of phthalate plasticizer, 0.2 parts by mass of BHA and 0.14 parts by mass of UV-P, add them into a twin-screw extruder for melt plasticization, set the extrusion temperature to 160°C and the die temperature to 175°C, and obtain a heat-insulating PVB film by extrusion casting with a specification of 0.76 mm.

[0041] Example 3

[0042] S1. Preparation of nano thermal insulation dispersion: add 10g of rare earth ytterbium oxide powder, 0.3g of sodium citrate and 80mg of sodium methyl nitrile sulfonate to 500g of hydrochloric acid solution with a mass concentration of 1.2% at 35°C, and stir for 1h to obtain a thermal insulation powder suspension. Use zirconium beads as ball milling beads, put the thermal insulation powder suspension into a ball mill for 1 hour, and then remove the ball milling beads to obtain a slurry. Rapidly adjust the pH value to less than 1 with hydrochloric acid, and treat the slurry in a centrifuge at a rotation speed of 1000rpm for 40min to obtain a nano thermal insulation dispersion with an average particle size of 20-50nm.

[0043] S2. At 35°C, 100g PVA and 1100g deionized water were added to a dissolving kettle, stirred to completely dissolve, and then 61g n-butyraldehyde was added to the PVA solution, and stirred at high speed for 30min to obtain a PVA / n-butyraldehyde mixed solution; 1261g of the above-mentioned PVA / n-butyraldehyde mixed solution and the dispersion prepared in step S1 were mixed in a mass ratio of 100:20, and continuously entered into a microreactor with heating and cooling functions through their respective pipelines within 12min, and all the materials were transferred to an aging kettle with a water bath temperature of 35°C, and the stirring speed was set to 60r / min. After reacting for 1h, the temperature was raised to 60°C at a heating rate of 1°C / 5min. After continuing the reaction for 1h, all the materials were transferred to a washing kettle, and then washed with deionized water. After centrifugation and drying, the insulating PVB resin powder was obtained.

[0044] S3. Take 75 parts by mass of the heat-insulating PVB resin powder prepared in step S2, 25 parts by mass of phthalate plasticizer, 0.25 parts by mass of BHA and 0.16 parts by mass of UV-P, add them into a twin-screw extruder for melt plasticization, set the extrusion temperature to 160°C and the die temperature to 175°C, and obtain a heat-insulating PVB film by extrusion casting with a specification of 0.76mm.

[0045] Example 4

[0046] S1. Preparation of nano thermal insulation dispersion: add 10g rare earth scandium oxide powder, 0.5g sodium citrate and 100mg sodium dodecyl sulfate to 500g hydrochloric acid solution with a mass concentration of 1.5% at 35°C, stir for 1h to obtain a thermal insulation powder suspension, put the thermal insulation powder suspension into a ball mill with zirconium beads as ball milling beads for 1 hour, then remove the ball milling beads to obtain a slurry, quickly adjust the pH value to less than 1 with hydrochloric acid, and treat the slurry in a centrifuge at a rotation speed of 1000rpm for 60min to obtain a nano thermal insulation dispersion with an average particle size of 20-50nm.

[0047] S2. At 35°C, 100g PVA and 1100g deionized water were added to a dissolving kettle, stirred to completely dissolve, and then 61g n-butyraldehyde was added to the PVA solution, and stirred at high speed for 30min to obtain a PVA / n-butyraldehyde mixed solution; 1261g of the above-mentioned PVA / n-butyraldehyde mixed solution and the dispersion prepared in step S1 were mixed in a mass ratio of 100:20, and continuously entered into a microreactor with heating and cooling functions through their respective pipelines within 12min, and all the materials were transferred to an aging kettle with a water bath temperature of 35°C, and the stirring speed was set to 60r / min. After reacting for 1h, the temperature was raised to 60°C at a heating rate of 1°C / 5min. After continuing the reaction for 1h, all the materials were transferred to a washing kettle, and then washed with deionized water. After centrifugation and drying, the insulating PVB resin powder was obtained.

[0048] S3. Take 75 parts by mass of the heat-insulating PVB resin powder prepared in step S2, 25 parts by mass of phthalate plasticizer, 0.3 parts by mass of BHA and 0.2 parts by mass of UV-P, add them into a twin-screw extruder for melt plasticization, set the extrusion temperature to 160°C and the die temperature to 175°C, and obtain a heat-insulating PVB film by extrusion casting with a specification of 0.76 mm.

[0049] Comparative Example 1

[0050] S1. At 35°C, 100g PVA and 1100g deionized water are added to a dissolving kettle, stirred to completely dissolve, and then 61g n-butyraldehyde is added to the PVA solution, and stirred at high speed for 30min to obtain a PVA / n-butyraldehyde mixed solution; 1261g of the above-mentioned PVA / n-butyraldehyde mixed solution and the dispersion prepared in step S1 are mixed in a mass ratio of 100:20, and continuously enter a microreactor with heating and cooling functions through their respective pipelines within 12min, and all the materials are transferred to an aging kettle with a water bath temperature of 35°C, and the stirring speed is set to 60r / min. After reacting for 1h, the temperature is increased to 60°C at a heating rate of 1°C / 5min. After continuing the reaction for 1h, all the materials are transferred to a washing kettle, and then washed with deionized water. After centrifugation and drying, the insulating PVB resin powder is obtained.

[0051] S2. Take 75 parts by mass of the heat-insulating PVB resin powder prepared in step S2, 25 parts by mass of phthalate plasticizer, 0.3 parts by mass of BHA and 0.2 parts by mass of UV-P, add them into a twin-screw extruder for melt plasticization, set the extrusion temperature to 160°C and the die temperature to 175°C, and obtain a heat-insulating PVB film by extrusion casting with a specification of 0.76 mm.

[0052] Comparative Example 2

[0053] S1. Preparation of nano thermal insulation dispersion: add 10g rare earth scandium oxide powder and 100mg sodium dodecyl sulfate to 500g hydrochloric acid solution with a mass concentration of 1.5% at 35°C, stir for 1h to obtain a thermal insulation powder suspension, put the thermal insulation powder suspension into a ball mill with zirconium beads as ball milling beads for 1 hour, then remove the ball milling beads to obtain a slurry, quickly adjust the pH value to less than 1 with hydrochloric acid, and treat the slurry in a centrifuge at a rotation speed of 1000rpm for 60min to obtain a nano thermal insulation dispersion with an average particle size of 20-50nm.

[0054] S2. At 35°C, 100g PVA and 1100g deionized water were added to a dissolving kettle, stirred to completely dissolve, and then 61g n-butyraldehyde was added to the PVA solution, and stirred at high speed for 30min to obtain a PVA / n-butyraldehyde mixed solution; 1261g of the above-mentioned PVA / n-butyraldehyde mixed solution and the dispersion prepared in step S1 were mixed in a mass ratio of 100:20, and continuously entered into a microreactor with heating and cooling functions through their respective pipelines within 12min, and all the materials were transferred to an aging kettle with a water bath temperature of 35°C, and the stirring speed was set to 60r / min. After reacting for 1h, the temperature was raised to 60°C at a heating rate of 1°C / 5min. After continuing the reaction for 1h, all the materials were transferred to a washing kettle, and then washed with deionized water. After centrifugation and drying, the insulating PVB resin powder was obtained.

[0055] S3. Take 75 parts by mass of the heat-insulating PVB resin powder prepared in step S2, 25 parts by mass of phthalate plasticizer, 0.3 parts by mass of BHA and 0.2 parts by mass of UV-P, add them into a twin-screw extruder for melt plasticization, set the extrusion temperature to 160°C and the die temperature to 175°C, and obtain a heat-insulating PVB film by extrusion casting with a specification of 0.76 mm.

[0056] Performance Testing

[0057] (1) The thermal insulation PVB resin powders prepared in Examples 1-4 were subjected to performance tests. The results are shown in Table 1.

[0058] Table 1:

[0059]

[0060]

[0061] (2) The heat insulation performance and optical performance of the heat insulation PVB films prepared in Examples 1-4 were tested, and the results are shown in Table 2. After the laminated glass was cleaned, the infrared transmittance tester with a central wavelength of 750nm and 2100nm was used to measure the infrared blocking rate of the corresponding wavelengths, and the full infrared blocking rate was tested on a solar film tester; the optical performance was tested on a transmittance haze meter after the laminated glass was cleaned.

[0062] Table 2:

[0063]

[0064] From Table 1 and Table 2, it can be seen that the PVB resin powder prepared by the present invention and the PVB film prepared therefrom can achieve an infrared blocking rate of more than 98% in the bands below 800 nm and above 2000 nm, and the infrared light blocking performance in the full band is significantly improved. The light transmittance meets the standard of thermal insulation PVB film, and the haze is greatly reduced compared with the ordinary thermal insulation film formula without the addition of sodium citrate additive, and the film has excellent infrared shielding performance and optical properties.

Claims

1. A method for preparing heat-insulating PVB resin powder, characterized in that: The steps include: S1. Add the insulation powder, sodium citrate and additives to the hydrochloric acid solution, stir well to obtain the insulation powder suspension, then ball mill to obtain the slurry, adjust the pH value of the slurry to less than 1 with hydrochloric acid and centrifuge to obtain the nano-insulation dispersion; S2. The PVA solution / n-butyraldehyde mixture is fully reacted with the nano-insulation dispersion, and the insulating PVB resin powder is obtained after washing, centrifugation and drying; Wherein, the thermal insulation powder is selected from rare earth element compounds.

2. The method for preparing a heat-insulating PVB resin powder according to claim 1, characterized in that: In step S1, the average diameter of the particles in the nano thermal insulation dispersion is 20 to 50 nm.

3. The method for preparing a heat-insulating PVB resin powder according to claim 1, characterized in that: In step S1, the rare earth element compound is one or more of boron lanthanum compound, cerium oxide, neodymium oxide, holmium oxide, ytterbium oxide, and scandium oxide.

4. The method for preparing a heat-insulating PVB resin powder according to claim 1, characterized in that: In step S1, the auxiliary agent is one or more of sodium dodecyl sulfate, sodium methyl nitrile sulfonate, and sodium methyl dimethylamine sulfonate.

5. The method for preparing a heat-insulating PVB resin powder according to claim 1, characterized in that: In step S1, the mass concentration of the hydrochloric acid solution is 0.5-1.5%.

6. The method for preparing a heat-insulating PVB resin powder according to claim 5, characterized in that: In step S1, the mass ratio of the thermal insulation powder, sodium citrate and the auxiliary agent is 1:(0.01-0.05):(0.005-0.01); the mass ratio of the thermal insulation powder to the hydrochloric acid solution is 1:(20-50).

7. The method for preparing a heat-insulating PVB resin powder according to claim 1, characterized in that: In step S2, the preparation method of the PVA / n-butyraldehyde mixed solution is: take 100 parts by mass of PVA and 670-1330 parts by mass of pure water at room temperature, add them into a dissolution kettle, heat it to 90°C-98°C, stir it thoroughly to make it completely dissolved into a PVA aqueous solution, then filter it, cool it to 35°C-50°C, add 50-65 parts by mass of n-butyraldehyde, stir it at high speed for 10min-40min, and obtain a uniform PVA / n-butyraldehyde mixed solution.

8. The method for preparing a heat-insulating PVB resin powder according to claim 1, characterized in that: The specific steps of step S2 are: PVA / n-butyraldehyde mixed solution and nano thermal insulation dispersion are continuously introduced into a tubular reactor with heating and cooling functions through their respective pipelines at a mass ratio of 5:1 within 8-12 minutes, and all materials are transferred to an aging kettle with an initial temperature of 30-40°C, and the stirring speed is set to 60-100r / min. After reacting for 1-2h, the temperature is increased to 50-65°C at a heating rate of 1°C / 5min. After continuing the reaction for 1-2h, all materials are transferred to a washing kettle, and then washed with deionized water. After centrifugation and drying, powdered thermal insulation PVB resin powder is obtained.

9. A method for preparing a heat-insulating PVB film, characterized in that: The antioxidant and the ultraviolet absorber are dissolved in the plasticizer, and the mixture is mixed evenly to prepare a mixed solution; the mixed solution and the heat-insulating PVB resin powder according to any one of claims 1 to 9 are extruded through a twin-screw extruder to obtain a heat-insulating PVB film.

10. The method for preparing a heat-insulating PVB film according to claim 9, characterized in that: The mass ratio of the heat-insulating PVB resin powder, the plasticizer, the antioxidant and the ultraviolet absorber is (70-75): (25-30): (0.15-0.35): (0.1-0.2).

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