PVC heat insulation film and preparation process thereof

Abstract

The application discloses PVC heat insulation film and a preparation process thereof, and belongs to the technical field of PVC heat insulation film. The PVC heat insulation film comprises a base film layer, a core body and a surface layer, wherein the base film layer is composed of the following components: 100 parts of PVC, 40-45 parts of dioctyl phthalate, 1.5-2 parts of calcium stearate and 20-25 parts of light calcium carbonate; the core body is composed of the following components: 100 parts of PVC, 40-45 parts of diisononyl phthalate, 3-3.5 parts of Ca / Zn composite stabilizer, 5-6 parts of cyan polyester amide and 6-10 parts of heat insulation filler; and the surface layer is composed of the following components: 100 parts of PVC, 30-40 parts of epoxy soybean oil, 3-3.5 parts of Ca / Zn composite stabilizer, 0.3-0.5 parts of nano SiO2 and 3-5 parts of light calcium carbonate. The PVC heat insulation film and the preparation process thereof can guarantee the heat insulation of the PVC heat insulation film, the basic light transmission effect and the size stability of the PVC heat insulation film.

Description

Technical Field

[0001] This invention specifically relates to a PVC heat insulation film and its preparation process, belonging to the field of PVC heat insulation film technology. Background Technology

[0002] PVC film is widely used in various coatings, such as PVC flooring film, architectural glass film, and automotive film. However, existing PVC films generally have poor heat insulation performance and are unsuitable for applications requiring heat insulation. Therefore, it is necessary to develop PVC films with heat insulation functions. For example, Chinese Patent Publication No. CN109929192A discloses a PVC heat insulation film and its preparation process. The PVC heat insulation film components, by weight, include 40-50 parts of PVC resin, 10-20 parts of chlorinated polyethylene, 3-9 parts of barium-zinc composite stabilizer, 4-10 parts of silica powder, 4-10 parts of hexamethylene diisocyanate, and silicon dioxide. The PVC heat insulation film prepared by this process, consisting of 3-9 parts micro powder, 1-3 parts nano titanium dioxide, 2-4 parts flame retardant, and 2-5 parts waterproofing agent, has excellent heat insulation, waterproofing, and fireproofing properties. It is used as a stretch film for the outer packaging of refrigerant canisters. However, since the PVC heat insulation film prepared by this process needs to have heat insulation function, heat insulation filler needs to be added, which can easily lead to a significant reduction in the light transmittance of the PVC heat insulation film and high overall production cost. In addition, the existing PVC film has a high heat shrinkage rate, which cannot meet the requirements of dimensional stability for lamination. After the PVC film is applied, it is easy to develop bubbles or peel off after sun exposure. Summary of the Invention

[0003] To address the aforementioned issues, this invention proposes a PVC heat insulation film and its preparation process, which, while ensuring the heat insulation properties of the PVC heat insulation film, also guarantees basic light transmission and improves the dimensional stability of the PVC heat insulation film.

[0004] The PVC heat insulation film of the present invention comprises: The base film layer is composed of the following components in total parts: PVC: 100 parts, dioctyl phthalate: 40-45 parts, calcium stearate: 1.5-2 parts, and light calcium carbonate: 20-25 parts. The base film layer serves as the supporting substrate for the entire PVC insulation film. PVC, as the matrix material, provides the main structural support and basic performance. Dioctyl phthalate, as the main plasticizer, reduces crystallinity by intercalating between PVC molecular chains, significantly improving the film's flexibility and ductility. By adjusting the ratio of PVC to dioctyl phthalate, the softness of the base film layer can be precisely controlled. It has good flexibility and excellent processing fluidity; calcium stearate has both heat stabilizer and lubricant functions. The heat stabilizer inhibits the release of HCl due to thermal decomposition during PVC processing and prevents material degradation; the lubricant function is to reduce molecular chain friction and improve melt flowability as an internal lubricant; by adding 20-25 parts of light calcium carbonate to the base film layer, the overall production cost per unit area of ​​PVC heat insulation film can be reduced, and light calcium carbonate can reduce the density per unit area of ​​PVC heat insulation film, reduce the overall weight of PVC heat insulation film, adjust the hardness and dimensional stability of the supporting substrate, and enhance tear resistance; The core is composed of the following components in total parts: PVC: 100 parts, diisononyl phthalate: 40-45 parts, Ca / Zn composite stabilizer: 3-3.5 parts, cyanopolyesteramide: 5-6 parts, and thermal insulation filler: 6-10 parts. The core, serving as the insulation core layer of the PVC insulation film, is encapsulated by PVC filler. PVC acts as the main support system for the core layer, while diisononyl phthalate (DIP) acts as a plasticizer to adjust overall flexibility, ensuring compatibility with the base film layer. This allows the core and base film layer to be co-extruded and calendered into a single unit. A Ca / Zn composite stabilizer inhibits thermal decomposition during PVC processing or use, preventing material degradation and discoloration caused by HCl removal reactions. Calcium-zinc stabilizers absorb HCl to form metal chlorides (such as...). It also has an internal lubrication function; the addition of cyanopolyesteramide to the core improves the high compatibility between PVC and heat insulation filler, making the heat insulation filler highly uniformly dispersed in PVC, effectively suppressing light scattering caused by agglomeration, and greatly reducing its negative impact on visible light transmittance; it enables the core to have heat insulation function while reducing the loss of light transmittance. In addition, cyanopolyesteramide can also improve melt flowability, reduce friction and sticking during processing, and improve antistatic effect. Top layer: The top layer is composed of the following components in total parts: PVC: 100 parts, epoxidized soybean oil: 30-40 parts, Ca / Zn composite stabilizer: 3-3.5 parts, nano SiO2: 0.3-0.5 parts, light calcium carbonate: 3-5 parts; The outer layer of the PVC heat insulation film is made of nano-SiO2 with a specific refractive index. 2， Nano-SiO2, used as a light transmittance enhancer, ensures a visible light transmittance greater than 92% through selective micro-refractive index matching, minimizing light scattering loss and exhibiting good surface hardness and weather resistance. PVC serves as the main support system for the core layer, while epoxidized soybean oil acts as a plasticizer, adjusting overall flexibility to match the core's flexibility, thus enabling the co-extrusion and calendering of the surface layer and core. Epoxidized soybean oil replaces traditional phthalates as a plasticizer, suitable for applications with high safety requirements such as food contact. Furthermore, the reaction of epoxidized soybean oil with HCl to generate chloroethanol replaces unstable chlorine atoms in PVC, inhibiting degradation. Additionally, the combination of epoxidized soybean oil and Ca / Zn composite stabilizers... After compounding and co-extrusion delay, epoxidized soybean oil and the Ca / Zn composite stabilizer of the core form a compound, further improving the thermal stability and weather resistance of the surface layer and the area between the surface layer and the core; nano-SiO2 can improve the wear resistance and barrier properties of PVC heat insulation film; the silanol groups on the surface of nano-SiO2 have a weak electrostatic interaction with the calcium ions of light calcium carbonate, which can form a local cross-linking network; in the surface layer of PVC heat insulation film, this network can bind the migration of plasticizer molecules and reduce the risk of precipitation caused by polarity mismatch; and nano-SiO2 and light calcium carbonate work synergistically to reduce filler agglomeration: the high oil absorption value of calcium carbonate is balanced by the low oil absorption value of silica, reducing the local dissipation of plasticizer and maintaining the fluidity of the processing melt; The thickness of the base film layer is 42 μm, the thickness of the core is 22 μm, and the thickness of the surface layer is 16 μm.

[0005] Furthermore, the mass ratio of the Ca / Zn composite stabilizer is 5:1; for example, the mass ratio of calcium stearate and zinc stearate is 5:1.

[0006] Further, the base film layer is composed of the following components in total parts: PVC: 100 parts, dioctyl phthalate: 40 parts, calcium stearate: 2 parts, and light calcium carbonate: 25 parts; the core is composed of the following components in total parts: PVC: 100 parts, diisononyl phthalate: 40 parts, Ca / Zn composite stabilizer: 3 parts, cyanopolyesteramide: 5 parts, and heat-insulating filler: 8 parts; the surface layer is composed of the following components in total parts: PVC: 100 parts, epoxidized soybean oil: 40 parts, Ca / Zn composite stabilizer: 3 parts, nano-SiO2: 0.4 parts, and light calcium carbonate: 5 parts.

[0007] Furthermore, the heat-insulating filler is one or both of inorganic powder with high near-infrared reflectivity and organic infrared absorber with specific absorption bands; the heat-insulating filler can achieve efficient blocking of the near-infrared band (the main heat source) in sunlight; while achieving an average reflectivity of ≥80% or an absorptivity of ≥70% in the 780-2500nm band, cyanopolyesteramide is used as a compatibilizer to improve the compatibility and dispersion stability between PVC, inorganic powder and organic infrared absorber, minimizing the light scattering caused by agglomeration and the impact on visible light transmission.

[0008] Furthermore, the inorganic powder is one or more of modified titanium dioxide, antimony-doped tin oxide, and indium tin oxide, the inorganic powder has a particle size ≤100nm, and the organic infrared absorber is transparent phthalocyanine blue or transparent phthalocyanine green.

[0009] Furthermore, the heat-insulating filler is composed of inorganic powder and organic infrared absorber in a weight ratio of 7:1.

[0010] Furthermore, the transparent phthalocyanine blue is one of phthalocyanine blue BGS, BASF L6905F or L6960F; the transparent phthalocyanine green is phthalocyanine green G (5319) or BASF K8730 (PG7).

[0011] A process for preparing PVC heat insulation film, the process being as follows: s1. Ingredients: The components of the base film layer, core, and surface layer are mixed evenly in their respective high-speed mixers according to the formula ratio to obtain three sets of mixed components; s2, Melt Plasticization: The three mixed groups are added to three single-screw extruders for melt plasticization to obtain three molten materials; s3, Multi-layer co-extrusion: Using a multi-layer die head with flow channels that match the number of film layers, three streams of molten material are extruded simultaneously and merged in the die head to form a layered melt; s4. Calendering or casting to form a film: The layered melt is calendered through the gap between the rollers of a calender or cast through a casting cooling roller to obtain a shaped film. s5. Cooling, shaping and winding: The film is fully cooled and shaped, then wound up after traction and trimming to obtain the finished PVC film.

[0012] Furthermore, the temperature control of the three single-screw extruders is as follows: 150-160℃ in the feeding section, 170-180℃ in the melting section, and 170-175℃ in the homogenization section and die head; the calender is a three-roll calender; the temperature of the upper roll of the three-roll calender is 80±2℃, the temperature of the middle roll is 85±2℃, and the temperature of the lower roll is 90±2℃; the layered melt is calendered into a film by the calender and then initially cooled before entering the cooling, shaping, and traction winding process.

[0013] Compared with existing technologies, the PVC heat insulation film and its preparation process of the present invention have a surface layer that serves as a protective layer for the core, protecting the core layer and ensuring the wear resistance of the entire heat insulation film surface, while minimizing visible light transmission loss. In addition, the surface layer, through the combination of lightweight calcium carbonate rigid support and a three-dimensional silica network, can suppress the thermal shrinkage of the heat insulation film. The core layer, as the core layer of heat insulation, can ensure the heat insulation effect while reducing visible light transmission loss. The base layer, as the bottom layer with a large proportion of the overall heat insulation film thickness, can reduce the production cost, density, and weight per unit area of ​​the PVC heat insulation film, while ensuring the tear resistance of the entire heat insulation film. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the overall structure of the PVC heat insulation film of the present invention.

[0015] Figure reference numerals: 1. Basement membrane layer, 2. Core, 3. Surface layer. Detailed Implementation

[0016] The PVC heat insulation film of the present invention comprises: The base film layer 1 is composed of the following components in total parts: PVC: 100 parts, dioctyl phthalate: 40-45 parts, calcium stearate: 1.5-2 parts, and light calcium carbonate: 20-25 parts. The base film layer 1 serves as the supporting substrate for the entire PVC insulation film. PVC, as the matrix material, provides the main structural support and basic performance. Dioctyl phthalate, as the main plasticizer, reduces crystallinity by intercalating between PVC molecular chains, significantly improving the flexibility and ductility of the film. The ratio of PVC to dioctyl phthalate allows for precise control of the properties of the base film layer 1. It is soft, with good flexibility and excellent processing fluidity; calcium stearate functions as both a heat stabilizer and a lubricant. As a heat stabilizer, it inhibits the release of HCl due to thermal decomposition during PVC processing, preventing material degradation; as a lubricant, it reduces molecular chain friction and improves melt flowability. By adding 20-25 parts of light calcium carbonate to the base film layer 1, the overall production cost per unit area of ​​PVC heat insulation film can be reduced. Furthermore, light calcium carbonate can reduce the density per unit area of ​​PVC heat insulation film, reduce the overall weight of PVC heat insulation film, adjust the hardness and dimensional stability of the supporting substrate, and enhance tear resistance. Core 2, wherein the core 2 is composed of the following components in total parts: PVC: 100 parts, diisononyl phthalate: 40-45 parts, Ca / Zn composite stabilizer: 3-3.5 parts, cyanopolyesteramide: 5-6 parts, heat insulation filler: 6-10 parts; Core 2 serves as the heat insulation core layer of the PVC heat insulation film. The heat insulation filler in the core layer is encapsulated within PVC, which acts as the main support system. Diisononyl phthalate is used as a plasticizer to adjust the overall flexibility, ensuring compatibility with the flexibility of the base film layer 1. This allows core 2 and base film layer 1 to be co-extruded and calendered into one piece. A Ca / Zn composite stabilizer inhibits thermal decomposition during PVC processing or use, preventing material degradation and discoloration caused by the deHCl reaction. A calcium-zinc stabilizer absorbs HCl to form metal chlorides (such as...). It also has an internal lubrication function; cyanopolyesteramide is added to the core 2 to improve the high compatibility between PVC and heat insulation filler, so that the heat insulation filler is highly uniformly dispersed in PVC, effectively suppressing light scattering caused by agglomeration and greatly reducing its negative impact on visible light transmittance; it enables the core 2 to have heat insulation function while reducing the loss of light transmittance. In addition, cyanopolyesteramide can also improve melt flowability, reduce friction and sticking during processing, and improve antistatic effect. Surface layer 3: The surface layer 3 is composed of the following components in total parts: PVC: 100 parts, epoxidized soybean oil: 30-40 parts, Ca / Zn composite stabilizer: 3-3.5 parts, nano SiO2: 0.3-0.5 parts, light calcium carbonate: 3-5 parts; Surface layer 3 serves as the outer layer of the PVC heat insulation film. Surface layer 3 is made of nano-SiO with a specific refractive index matching. 2，Nano-SiO2, acting as a light transmittance enhancer, ensures a visible light transmittance greater than 92% through selective micro-refractive index matching, minimizing light scattering loss and exhibiting good surface hardness and weather resistance. Using PVC as the main support system for the core layer and epoxidized soybean oil as a plasticizer, the overall softness is adjusted to match the softness of the core 2, enabling the co-extrusion and calendering of the surface layer 3 and core 2 into a single unit. Epoxidized soybean oil replaces traditional phthalates as a plasticizer, suitable for applications with high safety requirements such as food contact. Furthermore, the reaction of epoxidized soybean oil with HCl to generate chloroethanol replaces unstable chlorine atoms in PVC, inhibiting degradation. Additionally, the combination of epoxidized soybean oil and a Ca / Zn composite stabilizer further enhances its effectiveness. Subsequently, during co-extrusion and delay, epoxidized soybean oil and the Ca / Zn composite stabilizer of core 2 form a compound, further improving the thermal stability and weather resistance of surface layer 3 and the relationship between surface layer 3 and core 2; nano-SiO2 can improve the wear resistance and barrier properties of PVC heat insulation film; the silanol groups on the surface of nano-SiO2 have a weak electrostatic interaction with the calcium ions of light calcium carbonate, which can form a local cross-linking network; in the surface layer 3 of PVC heat insulation film, this network can bind the migration of plasticizer molecules and reduce the risk of precipitation caused by polarity mismatch; and nano-SiO2 and light calcium carbonate work synergistically to reduce filler agglomeration: the high oil absorption value of calcium carbonate is balanced by the low oil absorption value of silica, reducing the local dissipation of plasticizer and maintaining the fluidity of the processing melt; The thickness of the base film layer 1 is 42 μm, the thickness of the core 2 is 22 μm, and the thickness of the surface layer 3 is 16 μm.

[0017] The mass ratio of the Ca / Zn composite stabilizer is 5:1; for example, the mass ratio of calcium stearate and zinc stearate is 5:1.

[0018] The heat-insulating filler is one or both of the following: inorganic powder with high near-infrared reflectivity and organic infrared absorber with specific absorption bands. The heat-insulating filler can achieve efficient blocking of the near-infrared band (the main heat source) in sunlight. While achieving an average reflectivity of ≥80% or an absorptivity of ≥70% in the 780-2500nm band, cyanopolyesteramide is used as a compatibilizer to improve the compatibility and dispersion stability between PVC, inorganic powder and organic infrared absorber, minimizing the light scattering caused by agglomeration and the impact on visible light transmission.

[0019] The inorganic powder is one or more of modified titanium dioxide, antimony-doped tin oxide, and indium tin oxide, and the inorganic powder has a particle size ≤100nm. The organic infrared absorber is transparent phthalocyanine blue or transparent phthalocyanine green.

[0020] The heat-insulating filler is composed of inorganic powder and organic infrared absorber in a weight ratio of 7:1.

[0021] The transparent phthalocyanine blue is one of the following: Phthalocyanine Blue BGS, BASF L6905F, or L6960F; all of the above transparent phthalocyanine blues are heat resistant (up to 300℃) and have high transparency, making them suitable for plastics and transparent coatings; the transparent phthalocyanine green is Phthalocyanine Green G (5319) or BASF K8730 (PG7), and the above transparent phthalocyanine green has high transparency and strong weather resistance, making it suitable for use in transparent masterbatches.

[0022] A process for preparing PVC heat insulation film, the process being as follows: s1. Ingredients: The components of base film layer 1, core 2 and surface layer 3 are mixed evenly in their respective high-speed mixers according to the formula ratio to obtain three mixed components; s2, Melt Plasticization: The three mixed groups are added to three single-screw extruders for melt plasticization to obtain three molten materials; s3, Multi-layer co-extrusion: Using a multi-layer die head with flow channels that match the number of film layers, three streams of molten material are extruded simultaneously and merged within the die head to form a layered melt; s4. Calendering or casting to form a film: The layered melt is calendered through the gap between the rollers of a calender or cast through a casting cooling roller to obtain a shaped film. s5. Cooling, Shaping, and Traction Winding: The film is fully cooled and shaped, then pulled, trimmed, and wound to obtain the finished PVC film.

[0023] The temperature control of the three single-screw extruders is as follows: feeding section 150-160℃, melting section 170-180℃, homogenization section and die head temperature 170-175℃; the calender is a three-roll calender; the upper roll temperature of the three-roll calender is 80±2℃, the middle roll temperature is 85±2℃ and the lower roll temperature is 90±2℃; the layered melt is calendered into a film by the calender and then initially cooled before entering the cooling, shaping and traction winding process.

[0024] Example 1: The base film layer 1 is composed of the following components in total parts: PVC (S-700): 100 parts, dioctyl phthalate: 40 parts, calcium stearate: 2 parts, light calcium carbonate (1250 mesh): 25 parts; the core 2 is composed of the following components in total parts: PVC (S-1000): 100 parts, diisononyl phthalate: 40 parts, Ca / Zn composite stabilizer: 3 parts, cyanopolyesteramide: 5 parts, heat-insulating filler (particle size 50nm, inorganic powder is modified titanium dioxide): 8 parts; the surface layer 3 is composed of the following components in total parts: PVC (S-700): 100 parts, epoxidized soybean oil: 40 parts, Ca / Zn composite stabilizer: 3 parts, nano SiO2 (diameter ~30nm): 0.4 parts, light calcium carbonate (1250 mesh): 5 parts; the thickness of the base film layer 1 is 42μm, the thickness of the core 2 is 22μm, and the thickness of the surface layer 3 is 16μm; the Ca / Zn composite stabilizer is calcium stearate and zinc stearate in a mass ratio of 5:1.

[0025] According to the PVC heat insulation film preparation process and the component weight ratio of Example 1 of the present invention, a PVC heat insulation film was prepared, and 10 sheets of 10*10cm were randomly cut as the finished product of Example 1. Then, the finished product of Example 1 was tested, and 10 sets of experimental data were obtained. The mean value was calculated, and the following test results were obtained: Thermal insulation performance: Infrared blocking rate 84.1%; Light transmittance: Visible light transmittance 91.9%; Abrasion resistance: Haze <3% after 500 abrasion cycles with Taber; Tear resistance: ≥50N / mm in both longitudinal and transverse directions; Weight: 80g / m²; The preparation process for the comparative example is the same as that for Example 1, and the weight ratio of its components is as follows: Comparative Example 1: Based on the same components as Example 1, but without the heat-insulating filler, a PVC heat-insulating film with the same thickness as Example 1 was prepared in Comparative Example 1; and the following test results were obtained using the same testing method as Example 1: Thermal insulation performance: Infrared blocking rate reduced to 65%; Light transmittance: Visible light transmittance 93.0%; Abrasion resistance: Haze 3.2% after 500 abrasion cycles of Taber; Tear strength: 49 N / mm in both longitudinal and transverse directions; Weight 81 g / m²; As can be seen from Comparative Example 1, the thermal insulation performance decreased significantly, the light transmittance increased slightly, and the abrasion resistance and tear resistance were not much different. Comparative Example 2: 0.4 parts of nano-SiO2 were removed from the surface layer 3, and the remaining components were in the same weight ratio as those in Example 1; the test results are as follows: Thermal insulation performance: Infrared blocking rate 84.2%; Abrasion resistance: Haze 6% after 300 abrasion cycles with Taber; Tear resistance: 45 N / mm in both longitudinal and transverse directions; Light transmittance: Visible light transmittance 91.0%; Weight 79 g / m².

[0026] As shown in Comparative Example 2, the wear resistance and tear resistance decreased significantly, and the light transmittance decreased due to increased light scattering. Nano-SiO2 has a positive effect on changing the surface hardness and overall flexibility of the heat insulation film. Comparative Example 3: 10 parts of thermal insulation filler, 0.6 parts of nano-SiO2, and the remaining components were in the same weight ratio as those in Example 1; the test results are as follows: Thermal insulation performance: 88% infrared blocking rate, 90.2% visible light transmittance; Abrasion resistance: 2% haze after 600 abrasion cycles with Taber; Tear resistance: 55 N / mm in both longitudinal and transverse directions; Weight: 82 g / m². As shown in Comparative Example 3, the heat insulation and wear resistance are further improved, while the light transmittance is reduced, but it is still within the practical range.

[0027] Comparative Example 4: The heat insulation filler consisted of inorganic powder and organic infrared absorber in a weight ratio of 7:1; the organic infrared absorber was phthalocyanine green G (5319); the remaining components had the same weight ratio as those in Example 1; the test results are as follows: Thermal insulation performance: Infrared blocking rate 85.3%; Light transmittance: Visible light transmittance 91.8%; Abrasion resistance: Haze <3% after 500 abrasion cycles with Taber; Tear resistance: ≥50N / mm in both longitudinal and transverse directions; Weight: 79.7g / m²; As can be seen from Comparative Example 4, the wear resistance and tear strength are not much different from those of Example 1, and the heat insulation performance is further enhanced under the premise of minimal light transmittance loss.

[0028] Comparative Example 5: Core 2 was modified by removing cyano-free polyesteramide, and the remaining components were in the same weight ratio as those in Example 1; the test results are as follows: Infrared blocking rate: 84.2%; Light transmittance: Visible light transmittance: 88.9%; Tear resistance: 43 N / mm in both longitudinal and transverse directions; Weight: 79.7 g / m²; As shown in Comparative Example 5, cyano-free polyesteramide has a significant impact on light transmittance and tear resistance.

[0029] As can be seen from Examples 1 and Comparative Examples 1 to 5, the heat insulation filler of the core 2 is the core of heat insulation, and 8 parts is the balance point. Excessive filler will lead to a decrease in light transmittance. The synergistic optimization of nano-SiO2 and cyanopolyesteramide can improve the overall performance of the heat insulation film. The nano-SiO2 of the surface layer 3 can improve the wear resistance and tear resistance, and can also improve the light transmittance. The light calcium carbonate of the base film layer 1 and the cyanopolyesteramide of the core 2 work together to further improve the tear resistance and can effectively reduce the density.

[0030] The above embodiments are merely preferred embodiments of the present invention. Therefore, all equivalent changes or modifications made to the structure, features and principles described in the claims of the present invention are included within the scope of the present invention.

Claims

1. A PVC heat insulation film, characterized in that: include: The basement membrane layer is composed of the following components in total parts: PVC: 100 parts, dioctyl phthalate: 40-45 parts, calcium stearate: 1.5-2 parts, and light calcium carbonate: 20-25 parts. The core is composed of the following components in total parts: PVC: 100 parts, diisononyl phthalate: 40-45 parts, Ca / Zn composite stabilizer: 3-3.5 parts, cyanopolyesteramide: 5-6 parts, and thermal insulation filler: 6-10 parts. Top layer: The top layer is composed of the following components in total parts: PVC: 100 parts, epoxidized soybean oil: 30-40 parts, Ca / Zn composite stabilizer: 3-3.5 parts, nano SiO2: 0.3-0.5 parts, light calcium carbonate: 3-5 parts; The thickness of the base film layer is 42 μm, the thickness of the core is 22 μm, and the thickness of the surface layer is 16 μm; The heat-insulating filler is composed of inorganic powder with high near-infrared reflectivity and organic infrared absorber with specific absorption bands; the particle size of the inorganic powder is ≤100nm, and the weight ratio of the inorganic powder to the organic infrared absorber is 7:

1.

2. The PVC heat insulation film according to claim 1, characterized in that: The mass ratio of the Ca / Zn composite stabilizer is 5:

1.

3. The PVC heat insulation film according to claim 1, characterized in that: The base film layer is composed of the following components in total parts: 100 parts PVC, 40 parts dioctyl phthalate, 2 parts calcium stearate, and 25 parts light calcium carbonate; the core is composed of the following components in total parts: 100 parts PVC, 40 parts diisononyl phthalate, 3 parts Ca / Zn composite stabilizer, 5 parts cyanopolyesteramide, and 8 parts heat-insulating filler; the surface layer is composed of the following components in total parts: 100 parts PVC, 40 parts epoxidized soybean oil, 3 parts Ca / Zn composite stabilizer, 0.4 parts nano-SiO2, and 5 parts light calcium carbonate.

4. The PVC heat insulation film according to claim 1, characterized in that: The inorganic powder is one or more of modified titanium dioxide, antimony-doped tin oxide, and indium tin oxide, and the organic infrared absorber is transparent phthalocyanine blue or transparent phthalocyanine green.

5. The PVC heat insulation film according to claim 4, characterized in that: The transparent phthalocyanine blue is one of the following: phthalocyanine blue BGS, BASF L6905F or L6960F; the transparent phthalocyanine green is phthalocyanine green G or BASF K8730.

6. A process for preparing a PVC heat insulation film, used to prepare the PVC heat insulation film according to claim 1, characterized in that, The specific process is as follows: s1. Ingredients: The components of the base film layer, core, and surface layer are mixed evenly in their respective high-speed mixers according to the formula ratio to obtain three sets of mixed components; s2, Melt Plasticization: The three mixed components are added to three single-screw extruders for melt plasticization to obtain three molten materials; s3, Multi-layer co-extrusion: Using a multi-layer die head with flow channels that match the number of film layers, three streams of molten material are extruded simultaneously and merged within the die head to form a layered melt; s4. Calendering or casting to form a film: The layered melt is calendered through the gap between the rollers of a calender or cast through a casting cooling roller to obtain a shaped film. s5. Cooling, Shaping, and Traction Winding: The film is fully cooled and shaped, then pulled, trimmed, and wound to obtain the finished PVC film.

7. The PVC heat insulation film preparation process according to claim 6, characterized in that: The temperature control of the three single-screw extruders is as follows: feeding section 150-160℃, melting section 170-180℃, homogenization section and die head temperature 170-175℃; the calender is a three-roll calender; the upper roll temperature of the three-roll calender is 80±2℃, the middle roll temperature is 85±2℃ and the lower roll temperature is 90±2℃; the layered melt is calendered into a film by the calender and then initially cooled before entering the cooling, shaping and traction winding process.

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