A white recycled PETG heat shrinkable film and preparation method thereof

Abstract

The present invention provides a white recycled PETG heat shrinkable film and a preparation method thereof. The white environmentally friendly PETG heat shrinkable film adopts an A / B / A three-layer film structure design, wherein the A layer is placed on both sides of the core layer B. Layer A serves as a printing layer and contains PETG polyester chips, an anti-blocking agent, and a slip agent; layer B serves as a core layer and contains PETG polyester chips, bottle embryo recycled granules, and white masterbatch. The present invention uses recycled granules made from waste bottle embryos to replace part of the white masterbatch and part of the PETG polyester raw material. While reducing the production cost of the white recycled PETG heat shrinkable film, the resulting white recycled PETG heat shrinkable film also ensures excellent light-blocking properties and high whiteness, making it suitable for use on various bottles and meeting the requirements of green product development.

Description

Technical Field

[0001] The present application relates to the technical field of heat shrinkable film production, and in particular to a white recycled PETG heat shrinkable film and a preparation method thereof. Background Art

[0002] Heat-shrink film is a common packaging film. Its shrinkage upon application is often exploited to achieve a form-fitting effect or bundled wrapping, while also protecting contents from contamination or damage. Heat-shrink film shrinks by orienting the active molecular chains near their melting point or glass transition temperature during film production. This orientation is then rapidly solidified by cooling to below the crystallization point or glass transition temperature. Upon reheating above the melting point or glass transition temperature, the polymer chains regain their mobility, curling and orienting themselves, resulting in macroscopic film shrinkage.

[0003] Currently, the main heat shrink films used in packaging include polyvinyl chloride (PVC), polyethylene (PE), polystyrene (PS), modified polyethylene terephthalate glycol (PETG), and multi-layer co-extruded polyolefin (POF) heat shrink films. PVC heat shrink films often produce large amounts of hydrogen chloride and dioxin gases when incinerated, making them difficult to recycle and not environmentally friendly. Therefore, their application is limited. PE and POF heat shrink films offer excellent flexibility, strong impact and tear resistance, are durable, moisture-resistant, and have a wide shrinkage range, but they suffer from poor printing properties. PS heat shrink film offers excellent low-temperature stability and visual appeal during the shrinking process, but is temperature-sensitive and requires strict storage conditions. Its thickness uniformity is difficult to control, leading to fisheyes and color misregistration. Furthermore, PS heat shrink film requires specialized inks and solvents for printing, resulting in high costs. PETG heat shrink film offers excellent thickness uniformity, superior printing results, and is temperature-insensitive, making it easier to store, transport, and transport. PETG white heat shrink film is widely used in packaging dairy products and other products requiring UV protection due to its excellent light-blocking properties and visual appeal. However, the high cost of the white masterbatch used in this film has hampered its production and sales.

[0004] By using recycled waste bottle embryos to replace part of PETG raw materials, not only can environmental pollution be reduced, but also resources can be reused. Since they are processed from used plastics, waste bottle embryos have many impurities and poor color after granulation, and most of them can only be used as low-grade raw materials, which affects the overall performance of the film and is difficult to use in fields with high requirements for appearance and environmental protection. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a white recycled PETG heat shrinkable film and a preparation method thereof, which can reduce costs while meeting various performance indicators.

[0006] A white recycled PETG heat shrinkable film, comprising an extruded upper surface layer A, a core layer B, and a lower surface layer A, wherein the A layers are arranged on both sides of the B layer, wherein the A layers comprise 96-98 parts of PETG polyester chips, 1-2 parts of an anti-blocking agent, and 1-2 parts of a slip agent; and the B layers comprise 50-65 parts of PETG polyester chips, 5-30 parts of white bottle embryo regranules, and 5-15 parts of white masterbatch.

[0007] In some embodiments of the present invention, the opening agent in layer A is at least one of aluminum oxide, mica powder, kaolin or silicon dioxide.

[0008] In some embodiments of the present invention, the lubricant in layer A is at least one of stearamide, oleamide or styrene amide.

[0009] In some embodiments of the present invention, the mass ratio of the anti-blocking agent to the lubricating agent is 0.3-0.8:1-2.

[0010] In some embodiments of the present invention, the total thickness of the white recycled PETG heat shrinkable film is 20-80 μm.

[0011] In some embodiments of the present invention, the total thickness of the A layers on both sides of the B layer accounts for 15-20% of the total thickness of the white recycled PETG heat shrinkable film, and the thickness of the B layer accounts for 80-85% of the total thickness of the white recycled PETG heat shrinkable film.

[0012] In some embodiments of the present invention, the production process of the white preform recycled granules in layer B comprises the following steps:

[0013] Step 1: crush the white waste PET bottles, then pass clean water into the feed port to rinse the crushed bottle flakes, kill bacteria and viruses in the fragments through an ultraviolet sterilizer; rinse in a rinsing pot and bleach in a bleaching machine to remove pigments from the crushed bottle flakes;

[0014] Step 2: Add the dried chips and functional additives to a volumetric feeder with stirring, and steadily feed them into a twin-screw extruder through the feeder; the screw extruder temperature is 260-270°C;

[0015] Step 3: After the mixture obtained in step 2 is passed through a high vacuum system to remove low-volatile components, it enters a double-column, double-station, large-area screen changer to filter out impurities. The filtration temperature is 250-270°C and the filtration pressure is 20-30 MPa.

[0016] Step 4: The material obtained in step 3 is finally extruded through a strand die head and pelletized using an automatic strand drawing system to obtain the white bottle preform regranulate.

[0017] Furthermore, in step 1, a rotary dryer with a heating interlayer is used to remove a large amount of moisture remaining in the fragments during the cleaning process. Superheated steam is passed through the interlayer, and the fragments are rotated while being heated; the drying temperature is 100°C-150°C, and the rotation speed is 4-10 rpm.

[0018] Furthermore, in step 2, the functional additive comprises at least one of 7-hydroxycoumarin, a brightener, and bis(3,5-di-tert-butyl-4-hydroxybenzyl phosphate) calcium salt.

[0019] Furthermore, the addition amount of the 7-hydroxycoumarin accounts for 0.002-0.01 wt % of the total mass of the fragments.

[0020] Furthermore, the dosage of the brightener is 0.05-0.2 wt% of the total mass of the fragments, and specific products can be OM-LP-31-5, HS-DY-5, ML-PU-17-3, etc. purchased from Linyi Mingshuo Trading Co., Ltd.

[0021] Furthermore, the addition amount of the bis(3,5-di-tert-butyl-4-hydroxybenzylphosphonic acid monoethyl ester) calcium accounts for 0.01-0.1 wt % of the total mass of the fragments.

[0022] Furthermore, the functional additives include 0.002-0.01 wt% of 7-hydroxycoumarin based on the total mass of the fragments, 0.05-0.2 wt% of a brightener based on the total mass of the fragments, and 0.01-0.1 wt% of calcium bis(3,5-di-tert-butyl-4-hydroxybenzylphosphonate) based on the total mass of the fragments.

[0023] The presence of a brightener improves the brightness and smoothness of the resulting white preform recycled pellets. Calcium bis(3,5-di-tert-butyl-4-hydroxybenzylphosphonate) acts as an antioxidant, enhancing the heat-shrink film's resistance to oxidative yellowing. 7-Hydroxycoumarin, introduced into the heat-shrink film through preform recycled pellets, replaces environmentally harmful fluorescent brighteners and mitigates color variations in the recycled pellets.

[0024] Through certain creative experiments, the inventors concluded that if the three additives are present at the same time, the hue of the obtained white bottle embryo recycled pellets is uniform and can be evenly dispersed with the PETG polyester chips, ultimately making the light resistance of the obtained PETG white heat shrinkable film enhanced and the whiteness excellent.

[0025] When preparing the white preform recycled granules, the double-column double-station large-area screen changer used in step 3 has a large filtration area and a filtration accuracy of up to 15-20 μm, which can greatly reduce the impurity content of the preform recycled granules.

[0026] The preparation method of the above-mentioned white recycled PETG heat shrinkable film comprises the following steps:

[0027] SS1: Add PETG polyester chips, anti-blocking agent and slip agent into high-speed mixing equipment according to the metered amount to obtain layer A material;

[0028] SS2: PETG polyester chips, white masterbatch, and white preform recycled granules are added into another high-speed mixing equipment according to the metered amount to obtain layer B material;

[0029] SS3: The mixed materials of each layer are respectively put into the corresponding twin-screw vacuum extruder for melting and plasticization to obtain the melt of the upper and lower layers A and the core layer B; the temperature of the twin-screw extruder is 250-270℃;

[0030] SS4: After the impurities in the A and B layer melts are filtered out by a filter, the melt distribution system feeds each layer of melt into the die head corresponding to the A and B layer flow channels. The melts are combined and extruded at the die head, and after electrostatic adsorption, they are tightly attached to the quenching roller and rapidly cooled to obtain cast sheets.

[0031] SS5: After being preheated, the cast sheet enters a stretching machine for longitudinal and transverse stretching into a film. Finally, the film is shaped, cooled, and rolled to obtain the white recycled PETG heat shrink film.

[0032] Furthermore, the rotation speed of the high-speed mixing equipment in SS1 and SS2 is 400-600 rpm, and the stirring time is 5-10 min.

[0033] Furthermore, in SS1, when preparing the B layer material, 5-15 parts of ordinary bottle preform regranulation can be added, and the preparation process is the same as the preparation process of the above-mentioned white bottle preform regranulation, and the raw materials of the ordinary bottle preform regranulation do not contain white waste PET bottles.

[0034] Furthermore, in SS4, the extrusion temperature of the multi-layer die head is 250-270° C.; the temperature of the chill roll is 25-30° C.; and the linear speed of the rotation is 75-85 m / min.

[0035] Furthermore, in SS4, the extrusion mass ratio of the upper surface layer A, layer B and the lower surface layer A is 1:1-10:1.

[0036] Furthermore, in SS5, the transverse stretching ratio of the transverse and longitudinal stretching is 4.0-6.0 times, and the longitudinal stretching ratio is 1.0-4.0 times.

[0037] Beneficial effects: Compared with the prior art, the white recycled PETG heat shrinkable film provided by the present invention has the following advantages:

[0038] 1. When preparing the white preform recycled granules, the functional additives added make the obtained white preform recycled granules uniform, free of impurities, with stable hue and excellent dispersion performance;

[0039] 2. By adding white preform recycled granules to the core layer, the production cost is greatly reduced without affecting various performance indicators. At the same time, the obtained white recycled PETG heat shrinkable film has excellent light blocking and high whiteness, strong covering power, suitable for all kinds of bottle use needs, and meets the requirements of green product development. DETAILED DESCRIPTION

[0040] Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiments are only used to illustrate the present invention and are not used in limiting the scope of the present invention.In addition, should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall equally within the scope limited by the appended claims of the application.

[0041] The following is an exemplary description of the preparation process of the white preform regranulate used in the examples:

[0042] White preform recycled pellets #1

[0043] Step 1: crush the white waste PET bottles, then introduce clean water into the crusher feed port to rinse the crushed bottle flakes, and sterilize the fragments with an ultraviolet sterilizer to remove bacteria and viruses. The crushed bottle flakes are then rinsed in a rinsing pot and bleached in a bleaching machine to remove pigments. The fragments are then dried in a rotary dryer with a heating interlayer at a drying temperature of 100°C and a rotation speed of 4 rpm.

[0044] Step 2: 100 parts of the dried chips, 0.002 parts of 7-hydroxycoumarin, 0.05 parts of HS-DY-5, and 0.01 parts of calcium bis(3,5-di-tert-butyl-4-hydroxybenzylphosphonate) were added to a stirred plug volumetric feeder and steadily fed into a twin-screw extruder through the feeder; the screw extruder temperature was 260° C.

[0045] Step 3: The mixture obtained in step 2 is passed through a high vacuum system to remove low-volatile components, and then enters a double-column, double-station, large-area screen changer to filter out impurities. The filtration temperature is 250°C and the filtration pressure is 20 MPa.

[0046] Step 4: The material obtained in step 3 is finally extruded through a strand die head and pelletized using an automatic strand drawing system to obtain the white preform re-pellet material #1.

[0047] White preform recycled pellets #2

[0048] Step 1: crush the white waste PET bottles, then introduce clean water into the crusher feed port to rinse the crushed bottle flakes, and sterilize the fragments with an ultraviolet sterilizer to kill bacteria and viruses. The crushed bottle flakes are then rinsed in a rinsing pot and bleached in a bleaching machine to remove pigments. The fragments are then dried in a rotary dryer with a heating interlayer at a drying temperature of 120°C and a rotation speed of 7 rpm.

[0049] Step 2: 100 parts of the dried chips, 0.006 parts of 7-hydroxycoumarin, 0.1 parts of HS-DY-5, and 0.05 parts of calcium bis(3,5-di-tert-butyl-4-hydroxybenzylphosphonate) were added to a stirred plug volumetric feeder and steadily fed into a twin-screw extruder through the feeder; the screw extruder temperature was 260° C.

[0050] Step 3: The mixture obtained in step 2 is passed through a high vacuum system to remove low-volatile components, and then enters a double-column, double-station, large-area screen changer to filter out impurities. The filtration temperature is 260°C and the filtration pressure is 25 MPa.

[0051] Step 4: The material obtained in step 3 is finally extruded through a strand die and pelletized using an automatic strand drawing system to obtain the white preform pellet #2.

[0052] White preform regranulate #3

[0053] Step 1: crush the white waste PET bottles, then introduce clean water into the crusher feed port to rinse the crushed bottle flakes, and sterilize the fragments with an ultraviolet sterilizer to kill bacteria and viruses. The crushed bottle flakes are then rinsed in a rinsing pot and bleached in a bleaching machine to remove pigments. The fragments are then dried in a rotary dryer with a heating interlayer at a drying temperature of 150°C and a rotation speed of 10 rpm.

[0054] Step 2: 100 parts of the dried chips, 0.01 parts of 7-hydroxycoumarin, 0.2 parts of ML-PU-17-3, and 0.1 parts of bis(3,5-di-tert-butyl-4-hydroxybenzyl phosphate) calcium salt were added to a plug volumetric feeder with stirring, and the feed was steadily fed into a twin-screw extruder through the feeder; the screw extruder temperature was 270°C;

[0055] Step 3: The mixture obtained in step 2 is passed through a high vacuum system to remove low-volatile components, and then enters a double-column, double-station, large-area screen changer to filter out impurities at a filtration temperature of 270°C and a filtration pressure of 30 MPa.

[0056] Step 4: The material obtained in step 3 is finally extruded through a strand die head and pelletized using an automatic strand drawing system to obtain the white preform re-pellet material #3.

[0057] White preform recycled pellets #4

[0058] The process is similar to that of white preform regranulate #3, except that the amount of 7-hydroxycoumarin added is 0.015 parts.

[0059] White preform recycled pellets #5

[0060] The process is similar to that of white preform repellet #3, except that no 7-hydroxycoumarin is added.

[0061] Ordinary preform regranulation

[0062] The process is similar to that of white preform regranulate #3, except that the waste PET bottles used are ordinary transparent PET bottles (not white).

[0063] The PETG polyester chips used in the following examples are all YH101 from Yuanhong.

[0064] Example 1

[0065] SS1: 98 parts of PETG polyester chips, 1 part of aluminum oxide, and 1 part of stearamide were placed in a high-speed mixer at 400 rpm and stirred for 5 minutes to obtain layer A material;

[0066] SS2: 65 parts of PETG polyester chips, 15 parts of white masterbatch, and 20 parts of white preform regranules #1 were placed in another high-speed mixer at 500 rpm and stirred for 8 minutes to obtain layer B material.

[0067] SS3: The mixed materials of each layer are respectively put into the corresponding twin-screw vacuum extruder for melting and plasticization to obtain the melt of layer A and layer B; the temperature of the twin-screw extruder is 250°C;

[0068] SS4: After the melts of layer A and layer B are filtered to remove impurities, the melt distribution system feeds each layer of melt into the die head corresponding to the flow channel of layer A and layer B. After the melts are combined and extruded at the die head, they are electrostatically adsorbed and tightly attached to the chill roll. After rapid cooling, the cast sheet is obtained; the extrusion temperature is 250℃, the temperature of the chill roll is 25℃, the rotation speed is 75m / min, and the extrusion mass ratio of the upper surface layer A, layer B and the lower surface layer A is 1:1:1

[0069] SS5: After being preheated, the cast sheet enters a stretching machine for stretching 1.2 times in the longitudinal direction and 4.5 times in the transverse direction into a film. The stretching temperature is controlled at 80°C. Finally, the film is shaped at 70°C, cooled, and rolled up to obtain the white recycled PETG heat shrinkable film. The film thickness is 40 μm, and the thickness ratio of A:B:A is 1:10:1.

[0070] Example 2

[0071] SS1: 96 parts of PETG polyester chips, 2 parts of mica powder and 2 parts of oleamide were placed in a high-speed mixer at 500 rpm and stirred for 9 minutes to obtain layer A material;

[0072] SS2: 60 parts of PETG polyester chips, 10 parts of white masterbatch, 20 parts of white preform regranules #2, and 10 parts of ordinary preform regranules were placed in another high-speed mixer at 400 rpm and stirred for 5 minutes to obtain layer B material;

[0073] SS3: The mixed materials of each layer are respectively put into the corresponding twin-screw vacuum extruder for melting and plasticization to obtain the melt of layer A and layer B; the temperature of the twin-screw extruder is 260°C;

[0074] SS4: After the melts of layer A and layer B are filtered to remove impurities, the melt distribution system feeds each layer of melt into the die head corresponding to the flow channel of layer A and layer B. After the melts are combined and extruded at the die head, they are electrostatically adsorbed and tightly attached to the chill roll. After rapid cooling, the cast sheet is obtained; the extrusion temperature is 260℃, the temperature of the chill roll is 25℃, the rotation speed is 80m / min, and the extrusion mass ratio of the upper surface layer A, layer B and the lower surface layer A is 1:5:1

[0075] SS5: After preheating, the cast sheet enters a stretching machine for stretching 1.0 times in the longitudinal direction and 4.5 times in the transverse direction into a film. The stretching temperature is controlled at 82°C. Finally, the film is shaped at 72°C, cooled, and rolled up to obtain the white recycled PETG heat shrinkable film. The film thickness is 45 μm, and the thickness ratio of A:B:A is 1:10:1.

[0076] Example 3

[0077] SS1: 97 parts of PETG polyester chips, 1.5 parts of silicon dioxide, and 1.5 parts of erucamide were placed in a high-speed mixer at 600 rpm and stirred for 10 minutes to obtain layer A material;

[0078] SS2: 60 parts of PETG polyester chips, 5 parts of white masterbatch, 25 parts of white preform regranules #3, and 10 parts of ordinary preform regranules were placed in another high-speed mixer at 600 rpm and stirred for 10 minutes to obtain layer B material;

[0079] SS3: The mixed materials of each layer are respectively put into the corresponding twin-screw vacuum extruder for melting and plasticization to obtain the melt of layer A and layer B; the temperature of the twin-screw extruder is 270°C;

[0080] SS4: After the melts of layer A and layer B are filtered to remove impurities, the melt distribution system feeds each layer of melt into the die head corresponding to the flow channel of layer A and layer B. After the melts are combined and extruded at the die head, they are electrostatically adsorbed and tightly attached to the chill roll. After rapid cooling, the cast sheet is obtained. The extrusion temperature is 270°C, the temperature of the chill roll is 30°C, the rotation speed is 85m / min, and the extrusion mass ratio of the upper surface layer A, layer B and the lower surface layer A is 1:10:1.

[0081] SS5: After being preheated, the cast sheet enters a stretching machine for stretching 4 times in the longitudinal direction and 6 times in the transverse direction into a film. The stretching temperature is controlled at 85°C. Finally, the film is shaped at 75°C, cooled, and rolled up to obtain the white recycled PETG heat shrinkable film. The film thickness is 50 μm, and the thickness ratio of A:B:A is 1:10:1.

[0082] Example 4

[0083] The process is similar to that of Example 3, except that the white preform regranulate #3 is replaced with the white preform regranulate #4.

[0084] Example 5

[0085] The process is similar to that of Example 3, except that the white preform regranulate #3 is replaced with the white preform regranulate #5.

[0086] Comparative Example 1

[0087] The process is similar to that of Example 3, except that when preparing the B layer material, no white preform regranulate #3 is added, and the core layer is 65 parts of PETG polyester chips, 25 parts of white masterbatch, and 10 parts of ordinary preform regranulate.

[0088] Comparative Example 2

[0089] The process is similar to that of Example 3, except that when preparing the B layer material, ordinary preform regranules and white preform regranules #3 are not added at the same time, and the core layer is 75 parts of PETG polyester chips and 25 parts of white masterbatch.

[0090] Performance Testing

[0091] Tensile strength and elongation at break: Tested in accordance with GB / T13022-1991 Test method for tensile properties of plastic films. The specimens were strips with a length of 150 mm and a width of (15 ± 0.1) mm. The distance between the fixtures was 100 mm. The test speed was (250 ± 25) mm / min.

[0092] Whiteness: tested using Hangzhou Daji Whiteness Meter WSB-VI;

[0093] Light transmittance: tested in accordance with the national standard "GB / T 2410-2008";

[0094] Hiding power: Use the Novo-Shade Duo+ reflectivity hiding power tester. Place the sample to be tested on a black and white test bench. Using hiding paper, measure first on a white substrate, then on a black substrate. The final hiding power value is automatically calculated and displayed.

[0095] The test results are shown in Table 1-1 and Table 1-2:

[0096]

[0097]

[0098] The data in Tables 1-1 and 1-2 demonstrate that the white recycled PETG heat-shrinkable film provided by the present invention, when excluding white preform regranulation and / or conventional white preform regranulation (Comparative Example 1-2), exhibits a whiteness of at least 82.0 and a light transmittance of at most 16.6%, while also exhibiting excellent mechanical properties and hiding power. When white preform regranulation and / or conventional preform regranulation are added, the resulting white recycled PETG heat-shrinkable film exhibits no significant decrease in mechanical strength, whiteness, light-blocking properties, or hiding power, and even slightly outperforms the performance of films without preform regranulation. In summary, the white recycled PETG heat-shrinkable film produced using the technical solution provided by the present invention not only reduces production costs but also ensures excellent mechanical properties, whiteness, and hiding power.

Claims

1. A white recycled PETG heat shrinkable film, characterized in that: It consists of an extruded upper surface layer A, a core layer B, and a lower surface layer A, wherein the A layer is arranged on both sides of the B layer; wherein the A layer contains 96-98 parts of PETG polyester chips, 1-2 parts of anti-blocking agent, and 1-2 parts of slip agent; the B layer contains 50-65 parts of PETG polyester chips, 5-30 parts of white preform regranules, and 5-15 parts of white masterbatch; The production process of the white preform recycled granules in layer B comprises the following steps: Step 1: crush the white waste PET bottles, then pass clean water into the crusher feed port to rinse the fragments, and kill bacteria and viruses in the fragments through an ultraviolet sterilizer; rinse in a rinsing pot, bleach in a bleaching machine to remove pigments from the fragments, and then dry the fragments; Step 2: Add the dried chips and functional additives to a volumetric feeder with stirring, and steadily feed them into a twin-screw extruder through the feeder; the screw extruder temperature is 260-270°C; Step 3: After the mixture obtained in step 2 is passed through a high vacuum system to remove low-volatile components, it enters a double-column, double-station, large-area screen changer to filter out impurities at a filtration temperature of 250-270°C and a filtration pressure of 20-30 MPa. Step 4: The material obtained in step 3 is finally extruded through a strand die head and pelletized using an automatic strand drawing system to obtain the white bottle preform regranulate; In step 2, the functional additives include 0.002-0.01 wt% of 7-hydroxycoumarin, 0.05-0.2 wt% of brightener, and 0.01-0.1 wt% of calcium bis(3,5-di-tert-butyl-4-hydroxybenzylphosphonate), based on the total mass of the fragments.

2. The white recycled PETG heat shrinkable film according to claim 1, characterized in that: The opening agent in the A layer is at least one of aluminum oxide, mica powder, kaolin or silicon dioxide; the lubricant is at least one of stearamide, oleamide or erucamide; the mass ratio of the opening agent to the lubricant is 1-1.5:1-2.

3. The white recycled PETG heat shrinkable film according to claim 1, characterized in that: The total thickness is 20-80 μm; the total thickness of the A layers on both sides of the B layer accounts for 15-20% of the total thickness of the white recycled PETG heat shrinkable film, and the thickness of the B layer accounts for 80-85% of the total thickness of the white recycled PETG heat shrinkable film.

4. The white recycled PETG heat shrinkable film according to claim 1, characterized in that: In step 1, the fragments are dried using a rotary dryer with a heating interlayer at a drying temperature of 100° C. to 150° C. and a rotation speed of 4 to 10 rpm.

5. The method for preparing the white recycled PETG heat shrinkable film according to any one of claims 1 to 4, characterized in that: The following steps are involved: SS1: Add PETG polyester chips, anti-blocking agent and slip agent into high-speed mixing equipment according to the metered amount to obtain layer A material; SS2: PETG polyester chips, white masterbatch, and white preform recycled granules are added into another high-speed mixing equipment according to the metered amount to obtain layer B material; SS3: The mixed materials of each layer are respectively put into the corresponding twin-screw vacuum extruder for melting and plasticization to obtain the melt of layer A and layer B; the temperature of the twin-screw vacuum extruder is 250-270℃; SS4: After the impurities in the A and B layer melts are filtered out by a filter, the melt distribution system feeds each layer of melt into the die head corresponding to the A and B layer flow channels. The melts are combined and extruded at the die head, and after electrostatic adsorption, they are tightly attached to the quenching roller and rapidly cooled to obtain cast sheets. SS5: After being preheated, the cast sheet enters a stretching machine for longitudinal and transverse stretching into a film. Finally, the film is shaped, cooled, and rolled to obtain the white recycled PETG heat shrink film.

6. The method for preparing the white recycled PETG heat shrinkable film according to claim 5, characterized in that: The rotation speed of the high-speed mixing equipment in SS1 and SS2 is 400-600 rpm, and the stirring time is 5-10 min.

7. The method for preparing the white recycled PETG heat shrinkable film according to claim 5, wherein: In SS4, the extrusion temperature of the multi-layer die is 250-270°C; the temperature of the chill roll is 25-30°C, and the rotation speed is 75-85m / min; the extrusion mass ratio of the upper surface layer A, layer B and the lower surface layer A is 1:1-10:

1.

8. The method for preparing the white recycled PETG heat shrinkable film according to claim 5, wherein In SS5, the transverse stretching ratio of the longitudinal and transverse stretching is 4.0-6.0 times, and the longitudinal stretching ratio is 1.0-4.0 times.

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