Super-thick heavy-load biodegradable heat shrinkage film with controllable shrinkage rate as well as preparation method and application of super-thick heavy-load biodegradable heat shrinkage film

Abstract

The invention relates to the technical field of biodegradable materials, and provides a super-thick heavy-load biodegradable heat shrinkage film with controllable shrinkage rate and a preparation method and application thereof. The preparation method comprises the following steps: adding 50-90 parts by weight of poly (butylene adipate-co-terephthalate) (PBAT), 10-40 parts by weight of polylactic acid (PLA), 1-5 parts by weight of a plasticizer, 0.1-5 parts by weight of a compatilizer, 0.1-1 part by weight of an antioxidant, 0.1-1 part by weight of an anti-hydrolysis agent, 0.1-1 part by weight of a lubricant, 0.1-1 part by weight of a dispersant and the like into a high-speed mixer step by step according to a particle-liquid-powder sequence for mixing; carrying out melt extrusion and granulation through a double-screw extruder to prepare the modified material for the biodegradable heat shrinkage film; plasticizing the modified material for the thermal shrinkage film in a film blowing machine, upwards extruding and blowing to form a first film bubble with the blowing ratio of 1-4, and cooling and drafting to form a film; performing hot bath and secondary huffing to form a second film bubble with the draw ratio of 2-5; and cooling and shaping through a cold water jacket, drawing and rolling to form the biodegradable thermal shrinkage film. The biodegradable thermal shrinkage film prepared by the preparation method provided by the invention is controllable in shrinkage rate and thick in film thickness, and can be used for packaging heavy objects.

Description

Technical Field

[0001] This application belongs to the field of biodegradable materials technology, and in particular relates to a controllable shrinkage rate, ultra-thick heavy-duty biodegradable heat shrink film, its preparation method and application. Background Technology

[0002] Heat shrink film is a type of polymer film commonly used in packaging. It possesses excellent stability, sealing properties, and moisture and dust resistance, and is widely used in food, pharmaceuticals, sterilized tableware, stationery, crafts and gifts, and electronics. Currently, common processing methods for heat shrink film include: single-bubble blown film, double-bubble blown film, three-layer co-extrusion blown film, and biaxial stretch casting. Among these, single-bubble blown film has simple equipment and low cost, but the blow-up ratio is limited by the processability of the film bubble support, resulting in significant anisotropy in the heat shrinkage rate. Furthermore, single-bubble blown film suffers from low product cooling efficiency, leading to low transparency and significantly reduced visibility of the packaged contents. Three-layer co-extrusion blown film has high equipment investment costs, requires large and spacious areas, and has high complexity in process control. In addition, the shrinkage rate, optical properties, and other physical properties are significantly affected by the thickness ratio of each of the three layers. Compared to single-bubble blown film and three-layer co-extrusion blown film, the shrinkage rate of heat-shrinkable film produced by biaxial stretching casting is controllable through the stretching ratio in the transverse and longitudinal directions. However, it requires a large-scale casting-stretching combined unit, which is complex, expensive, and energy-intensive, making it difficult to promote and popularize in the application of disposable products. In contrast, the double-bubble blown film method achieves controllable shrinkage rate by adjusting the stretching and blow-up ratios in the longitudinal and transverse directions through secondary blowing, thus obtaining the same effect as the biaxial stretching casting process to meet the needs of different applications.

[0003] Existing biodegradable heat shrink films for packaging heavy items primarily use PLA and toughening materials. Excessive use of PLA provides the shrinkage effect, leading to high stiffness and brittleness in the film. Toughening materials aim to reduce brittleness and improve toughness, but their excessive proportion results in low film strength and shrinkage rate. Furthermore, excessively thick biodegradable heat shrink films lead to incomplete heat shrinkage, while excessively thin films have low strength and cannot meet the requirements for heavy-duty packaging. Patent CN 115109397 A uses a three-layer co-extrusion double-bubble method to prepare biodegradable heat shrink films, exhibiting excellent heat shrinkage rate at 100°C. However, the three layers are mainly composed of polylactic acid, resulting in high stiffness and brittleness, insufficient flexibility, and low tear strength, failing to meet the packaging requirements for heavy items. Patent CN 117343365 A uses a double-bubble blown film method to prepare biodegradable heat shrink film. Since the heat shrink film is prepared mainly with PBAT and supplemented with PLA, the tensile strength and shrinkage rate are both low, and the thickness of the film is 25 μm, which cannot meet the requirements for heavy-duty packaging applications.

[0004] Based on the above, it is therefore very important to find a way to prepare a biodegradable heat shrink film with controllable shrinkage, high shrinkage, large thickness, and the ability to package heavy objects using the double-bubble blown film method. Summary of the Invention

[0005] The primary objective of this application is to provide a modified material for a heavy-duty biodegradable heat shrink film with controllable shrinkage rate and ultra-thickness, and a method for preparing the same.

[0006] Another objective of this application is to provide a controllable shrinkage rate, ultra-thick heavy-duty biodegradable heat shrink film, its preparation method, and its application.

[0007] To achieve the above objectives, this application adopts the following technical solution: (1) A modified material for a heavy-duty biodegradable heat shrink film with controllable shrinkage rate and ultra-thickness, comprising 50-90 parts by weight of polybutylene adipate terephthalate (PBAT), 10-40 parts by weight of polylactic acid (PLA), 1-5 parts by weight of plasticizer, 0.1-5 parts by weight of compatibilizer, 0.1-1 parts by weight of antioxidant, 0.1-1 parts by weight of anti-hydrolysis agent, 0.1-1 parts by weight of opening agent, and 0.1-1 parts by weight of dispersant.

[0008] Furthermore, the plasticizer is one or more combinations of epoxidized soybean oil, acetylated tributyl citrate, tributyl citrate, and polyethylene glycol.

[0009] Furthermore, the compatibilizer is one or more combinations of maleic anhydride-grafted PBAT, maleic anhydride-grafted PLA, glycidyl methacrylate-grafted PBAT, glycidyl methacrylate-grafted PLA, or epoxy copolymers (ADR 4468).

[0010] Furthermore, the antioxidant is one or more combinations of antioxidant 168, antioxidant 1010, and antioxidant 1076.

[0011] Furthermore, the anti-hydrolysis agent is one or more combinations of monomeric carbodiimide and polymeric carbodiimide.

[0012] Furthermore, the opening agent is one or more combinations of oleamide, erucamide, and pentaerythritol stearate.

[0013] Furthermore, the dispersant is white oil.

[0014] (2) A method for preparing a modified material for a heavy-duty biodegradable heat shrink film with controllable shrinkage rate and ultra-thickness, comprising the following steps: adding PBAT, PLA, plasticizer, compatibilizer, antioxidant, anti-hydrolysis agent, opening agent and dispersant in a stepwise manner to a high-speed mixer in the order of particles-liquid-powder; melting and extruding the uniformly mixed raw materials through a twin-screw extruder, air cooling and pelletizing to obtain the modified material for biodegradable heat shrink film.

[0015] Furthermore, the processing temperature of the twin-screw extruder is 160~185 ℃, and the screw speed is 200~300 r / min.

[0016] (3) A method for preparing a heavy-duty biodegradable heat shrink film with controllable shrinkage rate and ultra-thickness, comprising the following steps: plasticizing the biodegradable heat shrink film with modified material through a blown film machine, extruding and blowing upward to form a first film bubble, and cooling and stretching it into a film; passing it through a hot water bath and blowing it again to form a second film bubble; cooling and shaping it through a cold water jacket, drawing it, and winding it up to obtain the biodegradable heat shrink film.

[0017] Furthermore, the processing temperature of the blown film machine is 150~170 ℃, the hot water bath temperature is 60~90 ℃, the cold water jacket temperature is 15~30 ℃, and the cold water jacket size is constant.

[0018] Furthermore, the inflation ratio of the first membrane bubble is 1 to 4, and the stretching ratio of the second membrane bubble is 2 to 5.

[0019] Furthermore, the thickness of the biodegradable heat-shrinkable film is 50~80 μm.

[0020] (4) Application of a heavy-duty biodegradable heat shrink film with controllable shrinkage rate and ultra-thickness, wherein the heavy-duty biodegradable heat shrink film can be used for packaging heavy items such as bottled water and bottled beverages.

[0021] The beneficial effects of this application are: (1) Through secondary inflation and process control, the ultra-thick biodegradable heat shrink film has a high shrinkage rate and the shrinkage rate is controllable.

[0022] (2) Compared with the existing biaxial stretching casting process for producing biodegradable heat shrink film, the double bubble blown film method can not only achieve similar effects, but also has lower equipment cost and unit energy consumption.

[0023] (3) The water ring cooling and shaping method makes the transparency of the biodegradable heat shrink film better than that of the single-bubble blown film method and the three-layer co-extrusion blown film method.

[0024] (4) Fill the gap in the use of biodegradable heat shrink film for heavy-duty packaging (bottled water, canned beverages). Attached Figure Description

[0025] Figure 1 This is a flowchart of the preparation method for an ultra-thick, heavy-duty biodegradable heat shrink film with controllable shrinkage rate;

[0026] Figure 2 This is a macroscopic view of an ultra-thick, heavy-duty biodegradable heat-shrinkable film with controllable shrinkage rate;

[0027] Figure 3 Applications of ultra-thick, heavy-duty biodegradable heat shrink film with controllable shrinkage rate. Figure 1 ; Figure 4 Applications of ultra-thick, heavy-duty biodegradable heat shrink film with controllable shrinkage rate. Figure 2 . Detailed Implementation

[0028] The present application will be further described in detail below with reference to the embodiments. However, those skilled in the art should understand that the embodiments are merely to help understand the present application and should not be regarded as specific limitations on the present application.

[0029] Unless otherwise specified, all materials mentioned in the following examples are commercially available.

[0030] Example 1 60 parts of polybutylene adipate terephthalate (PBAT), 40 parts of polylactic acid (PLA), 5 parts of epoxidized soybean oil, 0.25 parts of compatibilizer (ADR 4468), 0.2 parts of antioxidant 1010, 0.1 parts of antioxidant 168, 0.5 parts of polymeric carbodiimide, 0.8 parts of pentaerythritol stearate, and 0.05 parts of white oil were added stepwise to a high-speed mixer in the order of granules-liquid-powder and mixed. The uniformly mixed raw materials were extruded through a twin-screw extruder (zone temperatures: zone 1 90℃, zone 2 160℃, zone 3 170℃, zones 4-11 180℃, zone 12 175℃, screen changing 170℃, screw speed 250 r / min), air-cooled, and pelletized to obtain the modified material for heat shrink film.

[0031] The heat shrink film is plasticized using a modified material through a blown film machine (zone 1 150℃, zone 2 160℃, zone 3 165℃, zone 4 165℃, die head 160℃, screw speed 600 r / min), extruded upwards and blown to form a first film bubble with a blow-up ratio of 1.25, and then cooled and stretched into a film; after passing through a 65 ℃ hot water bath and undergoing a second blow-up to form a second film bubble; after cooling and shaping through a 20 ℃ cold water jacket, it is pulled with a stretch ratio of 3 and wound up to form a biodegradable heat shrink film.

[0032] Example 2 The difference between this embodiment and Embodiment 1 is that the inflation ratio of the first membrane bubble is 1.5.

[0033] Example 3 The difference between this embodiment and Embodiment 1 is that the inflation ratio of the first membrane bubble is 2.

[0034] Example 4 The difference between this embodiment and Embodiment 1 is that the inflation ratio of the first membrane bubble is 3.

[0035] Example 5 The difference between this embodiment and Embodiment 2 is that the stretching ratio of the second membrane bubble is 4.

[0036] The biodegradable heat-shrinkable films prepared in Examples 1-5 above were subjected to performance tests (thickness: tested according to GB / T 6672-2001 test method; tensile properties: tested according to GB / T 1040.3-2006 test method; right-angle tear strength: tested according to QB / T 1130-1991 test method; light transmittance and haze: tested according to GB / T 2410-2008 test method; heat shrinkage rate: tested according to GB / T 13519-2016 test method), and the test results are shown in Table 1.

[0037] Table 1. Performance test results of biodegradable heat shrink film

[0038] As shown in Table 1, the heavy-duty biodegradable heat-shrinkable film of this application possesses excellent mechanical and optical properties. Its high tensile strength and right-angle tear strength meet the requirements for bearing and handling heavy objects. By observing the heat shrinkage rates of Examples 1-4, adjusting the blow-up ratio of the first bubble gradually decreased the transverse shrinkage rate. By comparing the heat shrinkage rates of Examples 2 and 5, increasing the stretch ratio of the second bubble increased the longitudinal tensile strength and shrinkage rate. Therefore, the double-bubble blown film method, by adjusting the blow-up ratio of the first bubble and the stretch ratio of the second bubble, can achieve effects comparable to the biaxial stretching casting method, and also realizes controllable heat shrinkage rate of the heat-shrinkable film.

[0039] Figure 1 The production process is shown in the example.

[0040] Figure 2 These are macroscopic photographs of different specifications of biodegradable heat shrink films produced in Example 2, all neatly rolled up.

[0041] Figure 3These are actual photos of the biodegradable heat shrink film packaged in cardboard boxes (left image) and bottled water (right image) produced in Example 2. The left image shows that the biodegradable heat shrink film fits the cardboard box very well, with neat bullseye patterns, allowing the text on the cardboard to be clearly seen. The right image shows that the biodegradable heat shrink film packaged in bottled water (4*3 size) has a very high degree of compactness, with neat bullseye patterns.

[0042] The applicant declares that this application illustrates the detailed method of the present invention through the above embodiments, but this application is not limited to the above detailed method, that is, it does not mean that this application must rely on the above detailed method to be implemented. Those skilled in the art should understand that any improvements to this application, equivalent substitutions of the raw materials of the product of this application, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of this application.

Claims

1. A controllable shrinkage rate, ultra-thick heavy-duty biodegradable heat-shrinkable film and its preparation method, characterized in that, Includes the following steps: Step 1: Add polybutylene adipate terephthalate (PBAT), polylactic acid (PLA), plasticizer, compatibilizer, antioxidant, anti-hydrolysis agent, opening agent, and dispersant to a high-speed mixer in the order of granules-liquid-powder and mix them step by step. Step 2: The uniformly mixed raw materials are extruded through a twin-screw extruder, cooled (air-cooled), and pelletized to obtain a modified material for biodegradable heat shrink film; Step 3: The biodegradable heat shrink film is plasticized with modified material through a blown film machine, extruded upwards and blown to form the first film bubble, and then cooled and stretched into a film; after passing through a hot water bath, it is blown a second time to form the second film bubble; after being cooled and shaped by a cold water jacket, it is pulled and wound up to form the biodegradable heat shrink film.

2. A heavy-duty biodegradable heat-shrinkable film with controllable shrinkage rate and ultra-thickness, characterized in that, It consists of the following components in parts by weight: 50-90 parts of polybutylene adipate-terephthalate; Polylactic acid 10-40 parts; Plasticizer 1-5 parts; Compatibilizer 0.1-5 parts; Antioxidant 0.1 to 1 part; Anti-hydrolysis agent 0.1~1 part; 0.1 to 1 part of opening agent; Dispersant 0.1~1 parts.

3. The heavy-duty biodegradable heat-shrinkable film according to claim 1, characterized in that: The plasticizer is one or more of epoxidized soybean oil, acetylated tributyl citrate, tributyl citrate, and polyethylene glycol.

4. The heavy-duty biodegradable heat-shrinkable film according to claim 1, characterized in that: The compatibilizer is one or more combinations of maleic anhydride-grafted PBAT, maleic anhydride-grafted PLA, glycidyl methacrylate-grafted PBAT, glycidyl methacrylate-grafted PLA, or epoxy copolymers.

5. The heavy-duty biodegradable heat-shrinkable film according to claim 1, characterized in that: The antioxidant is one or more of antioxidant 168, antioxidant 1010, and antioxidant 1076.

6. The heavy-duty biodegradable heat-shrinkable film according to claim 1, characterized in that: The anti-hydrolysis agent is one or more combinations of monomeric carbodiimide and polymeric carbodiimide.

7. The heavy-duty biodegradable heat-shrinkable film according to claim 1, characterized in that: The opening agent is one or more of oleamide, erucamide, and pentaerythritol stearate.

8. The heavy-duty biodegradable heat-shrinkable film according to claim 1, characterized in that: The dispersant is white oil.

9. The heavy-duty biodegradable heat-shrinkable film according to claim 1, characterized in that: The processing temperature of the twin-screw extruder is 160~185 ℃, and the screw speed is 200~300 r / min.

10. The heavy-duty biodegradable heat-shrinkable film according to claim 1, characterized in that: The blown film machine has a processing temperature of 150~170 ℃, a hot water bath temperature of 60~90 ℃, and a cold water jacket temperature of 15~30 ℃.

11. The heavy-duty biodegradable heat-shrinkable film according to claim 1, characterized in that: The inflation ratio of the first membrane bubble is 1 to 4, and the stretching ratio of the second membrane bubble is 2 to 5.

12. A heavy-duty biodegradable heat-shrinkable film with controllable shrinkage rate and ultra-thickness, characterized in that, The biodegradable heat shrink film is produced by the method described in any one of claims 1 to 11.

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