A biodegradable bubble wrap

Abstract

The present invention discloses a biodegradable bubble film. By mass fraction, its raw material composition is as follows: 5-20 parts of modified PPC, 60-90 parts of PBAT, 5-20 parts of PLA, 0.1-5 parts of initiator, 0.1-5.0 parts of branching agent A, 0.1-5.0 parts of branching agent B, 0.2-1 part of antioxidant, and 0.1-1 part of slip agent. The present invention combines flexible PBAT and rigid PLA to prepare a blend with good flexibility. PPC is a carbon dioxide-based biodegradable plastic, which has the characteristics of good compatibility with PBAT and PLA, and PPC has good barrier properties. Introducing PPC into the PBAT / PLA blend can improve the mechanical properties and gas retention of the bubble film.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer materials, and particularly relates to a biodegradable bubble film and a preparation method thereof. Background Art

[0002] Bubble film is usually a product made from polyethylene as the main raw material, added with auxiliary materials such as whitening agents and antiblocking agents, and extruded and thermoformed into bubbles at high temperature. It has the characteristics of light texture, good transparency, sound insulation, shock absorption, etc., and can play roles such as moisture-proof, buffering, and heat preservation for products. It is widely used in anti-seismic buffer packaging of electronics, instruments, ceramics, handicrafts, household appliances, bicycles, kitchens, furniture and lacquer products, glass products, and precision instruments. Bubble film is an important packaging material with wide applications, and most of it is disposed of as domestic waste, making it difficult to be recycled on a large scale and easily causing serious environmental pollution problems.

[0003] The application of biodegradable materials is the preferred material for solving environmental pollution problems. However, at present, there is less research on the development and application of biodegradable bubble film. In the prior art, the invention patent with the application number 201610949553.0 discloses a biodegradable bubble film and its preparation process. Calculated by mass fraction, the biodegradable bubble film includes components: 10 - 20 parts of PLA, 70 - 80 parts of PBAT, 0.03 - 0.07 parts of antioxidant, 2 - 3 parts of biocompatible agent, 3 - 5 parts of heat-sealing aid, 1 - 2 parts of toughening agent, and 5 - 9 parts of inorganic filler. This biodegradable bubble film has degradability and excellent mechanical properties, but due to the large difference in compatibility and melting temperature between PLA and PBAT, it is unstable during extrusion processing, and the molten material is easily extruded during heat sealing, causing shrinkage and wrinkling at the heat-sealed part, resulting in a decrease in heat-sealing strength and impact resistance.

[0004] The application number 202111669443.6 discloses a carbon dioxide-based biodegradable shock-proof bubble film and its preparation method, which is prepared by mixing 50 - 70 parts of PPC and 30 - 50 parts of PBAT. In this invention, the melt strength of the raw material components is low, the melt viscosity is large, the processing stability of PPC is poor, and the product performance is poor.

[0005] Application No. 202110358422.6 provides a method for preparing a bubble film of a starch and PBAT composite material, comprising the following components: 60-90 parts of PBAT, 5-20 parts of starch, 5-20 parts of montmorillonite, 0.1-1 parts of lubricant, 0.1-3 parts of compatibilizer and 0.01-0.1 parts of stabilizer. In this invention, starch is added to PBAT as a filler. Starch is added as a bio-based raw material. Although it can accelerate the degradation cycle, the starch particles are large in size and uneven in particle size distribution. The surface of the particles is hydrophilic hydroxyl, which is incompatible with PBAT, often resulting in a decrease in the performance of the blend and its products. These shortcomings limit the application of biodegradable resins in the field of bubble bags. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention provides a biodegradable bubble film to solve the problems of poor performance of the current biodegradable bubble film materials and products thereof.

[0007] To achieve the above object, the present invention adopts the following technical solution:

[0008] A biodegradable bubble film comprises the following components, calculated by weight: 5-20 parts of modified PPC, 60-90 parts of PBAT, 5-20 parts of PLA, 0.1-5 parts of initiator, 0.1-5.0 parts of branching agent A, 0.1-5.0 parts of branching agent B, 0.2-1 parts of antioxidant and 0.1-1 parts of lubricant.

[0009] Furthermore, the modified PPC is prepared by mixing PPC and a capping agent at a mass ratio of 100:0.5 in a high-speed mixer at high speed, then adding the mixture into a twin-screw extruder for capping modification, and then extruding, drawing and pelletizing.

[0010] Furthermore, the end-capping agent includes one or more of maleic anhydride, phthalic anhydride, and pyromellitic anhydride.

[0011] Furthermore, the weight average molecular weight of the PPC is 30-120 KDa.

[0012] Furthermore, the rotation speed of the high-speed mixing is 300-1000 rpm, and the mixing time is 5-10 min.

[0013] Furthermore, the extrusion temperature of the twin-screw extruder used is 120-175° C., the die head temperature is 130-160° C., and the screw speed is 100-200 rpm.

[0014] Furthermore, the weight average molecular weight of the PBAT is 70-150 KDa.

[0015] Further, the weight-average molecular weight of the PLA is 160 - 300 KDa.

[0016] Further, the initiator is selected from one of bis(2,5-dimethyl-2,5-di(tert-butylperoxy)hexane) and dicumyl peroxide (DCP).

[0017] Further, the branching agent A is a polybutadiene liquid rubber with furan groups, which is prepared by first mixing hydroxyl-terminated polybutadiene liquid rubber and HDI at a molar ratio of 1:2, reacting at 70 °C for 60 min to obtain isocyanate-terminated polybutadiene liquid rubber, and then adding furfurylamine at a molar ratio of 2:1 to the isocyanate-terminated polybutadiene liquid rubber and continuing to react at 70 °C for 90 min.

[0018] Furthermore, the molecular weight of the hydroxyl-terminated polybutadiene liquid rubber is 1000.

[0019] Further, the branching agent B is bismaleimide or modified bismaleimide.

[0020] Further, the antioxidant is one or more of tea polyphenols, antioxidant 1076, antioxidant 1010, or antioxidant 168.

[0021] Further, the slip agent is one or more of erucamide, zinc stearate, ethylene bisstearamide, and polyethylene wax.

[0022] The preparation of the biodegradable bubble film includes the following steps:

[0023] (1) Dry PBAT, PLA, and modified PPC respectively.

[0024] (2) Weigh the dried PBAT, PLA, and modified PPC, and place them in a high-speed mixer together with the initiator, antioxidant, branching agent A, branching agent B, and slip agent in proportion for high-speed mixing.

[0025] (3) Place the mixed materials in a twin-screw extruder for melt blending, extrude and pelletize to obtain blended pellets.

[0026] (4) Put the obtained blended pellets into a bubble film casting machine for extrusion, traction, and winding to finally obtain the biodegradable bubble film.

[0027] Further, the temperature of the drying in step (1) is 60 - 100 °C, and the time is 2 - 12 h.

[0028] Further, the rotation speed of the high-speed mixing in step (2) is 300 - 1000 rpm, and the mixing time is 5 - 10 min.

[0029] Further, in step (3), the extrusion temperature of the twin-screw extruder is 120 - 190 °C, the die head temperature is 130 - 160 °C, and the screw speed is 100 - 300 rpm.

[0030] Further, in step (4), the extrusion temperature of the bubble film casting machine is 160 - 230 °C, the die head temperature is 180 - 230 °C, and the screw speed is 50 - 200 rpm.

[0031] The beneficial effects of the present invention are as follows:

[0032] 1. Compared with traditional PE bubble film, the main components in the present invention are all biodegradable materials, enabling the prepared bubble film to be fully biodegradable into carbon dioxide and water, which is green and environmentally friendly.

[0033] 2. The present invention uses PBAT, PLA, and modified PPC as the main materials to prepare the bubble film. The combination of flexible PBAT and rigid PLA can prepare a blend with good flexibility. PPC is a carbon dioxide-based biodegradable plastic, which has a low cost, good compatibility with PBAT and PLA, and good barrier properties. Introducing PPC into the PBAT / PLA blend can improve the mechanical properties and gas retention of the bubble film. Regarding the problem of poor thermal stability of PPC, the present invention conducts end-capping modification on it to improve the thermal stability and mechanical properties of PPC, and further improve the mechanical properties of the blend system.

[0034] 3. Liquid polybutadiene can increase the movement ability of resin molecular chains, improve the fluidity of the processing process, lower the melting point of PLA, and enhance the heat-sealing performance of the bubble film. Liquid polybutadiene rubber is a reactive plasticizer. The double bonds on its molecular chain can undergo grafting reactions with polymers (PPC, PBAT, and PLA) under the action of initiators to grow graft chains with hydrophobic characteristics. These graft chains are intertwined with the molecular chains of the polymer matrix or with each other, not only forming a denser molecular chain structure but also improving the interfacial bonding strength between different polymers. Therefore, it can greatly improve the barrier properties of the matrix resin. And liquid polybutadiene rubber with furan groups on its molecular chain can form a cross-linked structure in the presence of bismaleimide, further increasing the entanglement density of molecular chains and improving the mechanical properties and barrier properties of the blend modification system.

[0035] 4. Polymers and blends with permanent covalently cross-linked macromolecular networks generally cannot be reprocessed or reshaped, and the introduction of covalent cross-linked bonds easily leads to the problem of low polymer processing efficiency. The present invention utilizes polybutadiene liquid rubber with furan groups and (modified) bismaleimide to introduce dynamic covalent cross-linked bonds, which can realize the molecular chain cross-linked structure design of polymers and their blends. Due to the reversibility of dynamic covalent bonds, the performance of the blend can be directly improved during the polymer screw processing process. It is easy to achieve large-scale production and will not cause a decrease in polymer processing efficiency. The prepared blend has dynamic covalent cross-linked bonds that are untied during high-temperature processing, so that the polymer has excellent processing performance. After low-temperature molding, the dynamic characteristic covalent bonds recombine to form covalent cross-linked bonds, which increases the physical properties of the blend.

[0036] 5. The present invention has simple steps and strong operability. In view of the current high price of degradable materials, the use of this technical method has important significance and value for the development of a circular economy of degradable materials. DETAILED DESCRIPTION

[0037] A biodegradable bubble film, the preparation of which comprises the following steps:

[0038] (1) Dry PBAT, PLA and modified PPC at 60-100°C in vacuum for 2-12 hours respectively;

[0039] (2) According to the weight percentage, weigh 60-90 parts of dried PBAT, 5-20 parts of PLA, and 5-20 parts of modified PPC, and place them together with 0.1-5 parts of initiator, 0.2-1 parts of antioxidant, 0.1-5.0 parts of branching agent A, 0.1-5.0 parts of branching agent B, and 0.1-1 parts of lubricant in a high-speed mixer, and mix them at a speed of 300-1000 rpm for 5-10 minutes;

[0040] (3) placing the mixed materials in a twin-screw extruder for melt blending, extruding and granulating to obtain blended granules; the extrusion temperature of the twin-screw extruder is 120-190°C, the die temperature is 130-160°C, and the screw speed is 100-300rpm;

[0041] (4) placing the obtained blended pellets into a bubble film casting machine for extrusion, pulling, and winding to finally obtain the biodegradable bubble film; the extrusion temperature of the bubble film casting machine is 160-230° C., the die head temperature is 180-230° C., and the screw speed is 50-200 rpm.

[0042] Among them, the weight-average molecular weight of the PBAT described in step (1) is 70-150 KDa. The weight-average molecular weight of the PLA is 160-300 KDa. The modified PPC is prepared by placing PPC and a capping agent in a high-speed mixer at a mass ratio of 100:0.5 for high-speed mixing, then adding the mixture to a twin-screw extruder for capping modification, and then extruding, pelletizing, and cutting. The capping agent used includes one or more of maleic anhydride, phthalic anhydride, and pyromellitic dianhydride. The weight-average molecular weight of the PPC used is 30-120 KDa. The rotation speed of the high-speed mixing is 300-1000 rpm, the mixing time is 5-10 min, the extrusion temperature of the twin-screw extruder used is 120-175 °C, the die head temperature is 130-160 °C, and the screw rotation speed is 100-200 rpm.

[0043] The initiator described in step (2) is selected from one of bis(2,4-dichlorobenzoyl) peroxide and DCP. The branching agent A is prepared by first mixing hydroxyl-terminated polybutadiene liquid rubber and HDI at a molar ratio of 1:2 and reacting at 70 °C for 60 min to obtain isocyanate-terminated polybutadiene liquid rubber, and then adding furfurylamine at a molar ratio of 2:1 to the isocyanate-terminated polybutadiene liquid rubber and continuing to react at 70 °C for 90 min to obtain polybutadiene liquid rubber containing furan groups. The molecular weight of the hydroxyl-terminated polybutadiene liquid rubber used is 1000. The branching agent B is bismaleimide or modified bismaleimide. The antioxidant is one or more of tea polyphenols, antioxidant 1076, antioxidant 1010, or antioxidant 168. The slip agent is one or more of erucamide, zinc stearate, ethylene bisstearamide, and polyethylene wax.

[0044] To make the content of the present invention easier to understand, the technical solutions of the present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited thereto.

[0045] The modified PPC used is prepared by placing PPC (weight-average molecular weight of 95 KDa) and maleic anhydride (MA) in a high-speed mixer at a mass ratio of 100:0.5 and mixing at a rotation speed of 500 rpm for 10 min, then adding the mixture to a twin-screw extruder for capping modification, and then extruding, pelletizing, and cutting. The extrusion temperature of the twin-screw extruder is 120-175-175-175-175-175-175-175-175-175-175 °C, the die head temperature is 160 °C, and the screw rotation speed is 200 rpm.

[0046] The polybutadiene liquid rubber with furan groups used is prepared by first mixing hydroxyl-terminated polybutadiene liquid rubber (molecular weight of 1000) with HDI at a molar ratio of 1:2, reacting at 70 °C for 60 min to obtain isocyanate-terminated polybutadiene liquid rubber, and then adding furfurylamine at a molar ratio of 2:1 to the isocyanate-terminated polybutadiene liquid rubber and continuing to react at 70 °C for 90 min for preparation.

[0047] Example 1

[0048] A biodegradable bubble film, and its preparation method includes the following steps:

[0049] (1) Vacuum dry PBAT, PLA, and modified PPC at 60 °C for 5 h respectively;

[0050] (2) Weigh 75.0 parts of dried PBAT, 8.5 parts of PLA, 10.0 parts of modified PPC, 3.0 parts of polybutadiene liquid rubber with furan groups, 1.5 parts of bismaleimide, 0.5 part of antioxidant 168, 0.5 part of antioxidant 1010, 0.5 part of dicumyl peroxide, and 0.5 part of erucamide by mass, and place them in a high-speed mixer to mix at a high speed of 500 rpm for 10 min;

[0051] (3) Place the mixed materials in a twin-screw extruder for melt blending and extrusion granulation to obtain a special blending material; the extrusion temperature of the twin-screw extruder is 120 - 175 - 175 - 175 - 175 - 175 - 175 - 175 - 175 - 175 - 175 °C, the die head temperature is 160 °C, and the screw speed is 200 rpm;

[0052] (4) Put the obtained blended pellets into a bubble film casting machine for extrusion, traction, and winding to finally obtain a biodegradable bubble film; the extrusion temperature of the bubble film casting machine is 150 - 175 - 180 - 185 - 185 °C, the die head temperature is 200 - 195 - 190 - 185 - 185 - 190 - 195 - 200 °C, and the screw speed is 200 rpm.

[0053] Example 2

[0054] A biodegradable bubble film, and its preparation method includes the following steps:

[0055] (1) Vacuum dry PBAT, PLA, and modified PPC at 60 °C for 5 h respectively;

[0056] (2)Weigh 70.0 parts of dried PBAT, 8.5 parts of PLA, 15.0 parts of modified PPC, 3.0 parts of polybutadiene liquid rubber with furan groups, 1.5 parts of bismaleimide, 0.5 part of antioxidant 168, 0.5 part of antioxidant 1010, 0.5 part of dicumyl peroxide and 0.5 part of erucamide by mass fraction, and place them in a high-speed mixer. Mix at a high speed of 500 rpm for 10 min;

[0057] (3)Place the mixed materials in a twin-screw extruder for melt blending and extrusion granulation to obtain a special blending material; the extrusion temperature of the twin-screw extruder is 120 - 175 - 175 - 175 - 175 - 175 - 175 - 175 - 175 - 175 - 175 °C, the die head temperature is 160 °C, and the screw speed is 200 rpm;

[0058] (4)Put the obtained blended pellets into a bubble film casting machine for extrusion, traction, and winding to finally obtain a biodegradable bubble film; the extrusion temperature of the bubble film casting machine is 150 - 175 - 180 - 185 - 185 °C, the die head temperature is 200 - 195 - 190 - 185 - 185 - 190 - 195 - 200 °C, and the screw speed is 200 rpm.

[0059] Example 3

[0060] A method for preparing a biodegradable bubble film includes the following steps:

[0061] (1)Vacuum dry PBAT, PLA, and modified PPC at 60 °C for 5 h respectively;

[0062] (2)Weigh 65.0 parts of dried PBAT, 8.5 parts of PLA, 20.0 parts of modified PPC, 3.0 parts of polybutadiene liquid rubber with furan groups, 1.5 parts of bismaleimide, 0.5 part of antioxidant 168, 0.5 part of antioxidant 1010, 0.5 part of dicumyl peroxide and 0.5 part of erucamide by mass fraction, and place them in a high-speed mixer. Mix at a high speed of 500 rpm for 10 min;

[0063] (3)Place the mixed materials in a twin-screw extruder for melt blending and extrusion granulation to obtain a special blending material; the extrusion temperature of the twin-screw extruder is 120 - 175 - 175 - 175 - 175 - 175 - 175 - 175 - 175 - 175 - 175 °C, the die head temperature is 160 °C, and the screw speed is 200 rpm;

[0064] (4) Put the obtained blended pellets into a bubble film casting machine for extrusion, traction, and winding to finally obtain a biodegradable bubble film; the extrusion temperature of the bubble film casting machine is 150 - 175 - 180 - 185 - 185 °C, the die head temperature is 200 - 195 - 190 - 185 - 185 - 190 - 195 - 200 °C, and the screw speed is 200 rpm.

[0065] Example 4

[0066] A biodegradable bubble film, and its preparation method includes the following steps:

[0067] (1) Vacuum dry PBAT, PLA, and modified PPC at 60 °C for 5 h respectively;

[0068] (2) Weigh 55.0 parts of dried PBAT, 8.5 parts of PLA, 30.0 parts of modified PPC, 3.0 parts of polybutadiene liquid rubber with furan groups, 1.5 parts of bismaleimide, 0.5 part of antioxidant 168, 0.5 part of antioxidant 1010, 0.5 part of bis(2,5 - di - tert - butyl - 4 - methylphenyl) phosphite, and 0.5 part of erucamide by mass, and place them in a high - speed mixer, and mix at a speed of 500 rpm for 10 min;

[0069] (3) Put the mixed materials into a twin - screw extruder for melt blending and extrusion granulation to obtain a special blended material; the extrusion temperature of the twin - screw extruder is 120 - 175 - 175 - 175 - 175 - 175 - 175 - 175 - 175 - 175 - 175 °C, the die head temperature is 160 °C, and the screw speed is 200 rpm;

[0070] (4) Put the obtained blended pellets into a bubble film casting machine for extrusion, traction, and winding to finally obtain a biodegradable bubble film; the extrusion temperature of the bubble film casting machine is 150 - 175 - 180 - 185 - 185 °C, the die head temperature is 200 - 195 - 190 - 185 - 185 - 190 - 195 - 200 °C, and the screw speed is 200 rpm.

[0071] Comparative Example 1

[0072] A degradable bubble film, and its preparation method includes the following steps:

[0073] (1) Vacuum dry PBAT, PLA, and modified PPC at 60 °C for 5 h respectively;

[0074] (2) Weigh 65.0 parts of dried PBAT, 8.5 parts of PLA, 20.0 parts of modified PPC, 3.0 parts of hydroxyl-terminated polybutadiene liquid rubber, 1.5 parts of bismaleimide, 0.5 part of antioxidant 168, 0.5 part of antioxidant 1010, 0.5 part of bis(tert-butylperoxyisopropyl)benzene, and 0.5 part of erucamide by mass fraction, and place them in a high-speed mixer. Mix at a high speed of 500 rpm for 10 min.

[0075] (3) Place the mixed materials in a twin-screw extruder for melt blending and extrusion granulation to obtain a special blending material. The extrusion temperature of the twin-screw extruder is 120 - 175 - 175 - 175 - 175 - 175 - 175 - 175 - 175 - 175 - 175 °C, the die head temperature is 160 °C, and the screw speed is 200 rpm.

[0076] (4) Put the obtained blended pellets into a bubble film casting machine for extrusion, traction, and winding to finally obtain a biodegradable bubble film. The extrusion temperature of the bubble film casting machine is 150 - 175 - 180 - 185 - 185 °C, the die head temperature is 200 - 195 - 190 - 185 - 185 - 190 - 195 - 200 °C, and the screw speed is 200 rpm.

[0077] Comparative Example 2

[0078] A biodegradable bubble film, and its preparation method includes the following steps:

[0079] (1) Vacuum dry PBAT, PLA, and PPC at 60 °C for 5 h respectively.

[0080] (2) Weigh 65.0 parts of dried PBAT, 8.5 parts of PLA, 20.0 parts of PPC, 3.0 parts of hydroxyl-terminated polybutadiene liquid rubber, 1.5 parts of bismaleimide, 0.5 part of antioxidant 168, 0.5 part of antioxidant 1010, 0.5 part of bis(tert-butylperoxyisopropyl)benzene, and 0.5 part of erucamide by mass fraction, and place them in a high-speed mixer. Mix at a high speed of 500 rpm for 10 min.

[0081] (3) Place the mixed materials in a twin-screw extruder for melt blending and extrusion granulation to obtain a special blending material. The extrusion temperature of the twin-screw extruder is 120 - 175 - 175 - 175 - 175 - 175 - 175 - 175 - 175 - 175 - 175 °C, the die head temperature is 160 °C, and the screw speed is 200 rpm.

[0082] (4) Put the obtained blended pellets into a bubble film casting machine for extrusion, traction, and winding to finally obtain a biodegradable bubble film; the extrusion temperature of the bubble film casting machine is 150 - 175 - 180 - 185 - 185 °C, the die head temperature is 200 - 195 - 190 - 185 - 185 - 190 - 195 - 200 °C, and the screw speed is 200 rpm.

[0083] Comparative Example 3

[0084] A biodegradable bubble film, and its preparation method includes the following steps:

[0085] (1) Vacuum dry PBAT, PLA, and modified PPC at 60 °C for 5 h respectively;

[0086] (2) Weigh 65.0 parts of dried PBAT, 8.5 parts of PLA, 20.0 parts of modified PPC, 3.0 parts of PEG300, 1.5 parts of bismaleimide, 0.5 part of antioxidant 168, 0.5 part of antioxidant 1010, 0.5 part of bis(2,5 - di - tert - butylphenyl) pentaerythritol diphosphite, and 0.5 part of erucamide by mass, and place them in a high - speed mixer, and mix at a speed of 500 rpm for 10 min;

[0087] (3) Put the mixed materials into a twin - screw extruder for melt blending and extrusion granulation to obtain a special blended material; the extrusion temperature of the twin - screw extruder is 120 - 175 - 175 - 175 - 175 - 175 - 175 - 175 - 175 - 175 - 175 °C, the die head temperature is 160 °C, and the screw speed is 200 rpm;

[0088] (4) Put the obtained blended pellets into a bubble film casting machine for extrusion, traction, and winding to finally obtain a biodegradable bubble film; the extrusion temperature of the bubble film casting machine is 150 - 175 - 180 - 185 - 185 °C, the die head temperature is 200 - 195 - 190 - 185 - 185 - 190 - 195 - 200 °C, and the screw speed is 200 rpm.

[0089] Comparative Example 4

[0090] A biodegradable bubble film, and its preparation method includes the following steps:

[0091] (1) Vacuum dry PBAT, PLA, and modified PPC at 60 °C for 5 h respectively;

[0092] (2)Weigh 65.0 parts of dried PBAT, 10 parts of PLA, 10.0 parts of modified PPC, 3.0 parts of polybutadiene liquid rubber with furan groups, 0.5 part of antioxidant 168, 0.5 part of antioxidant 1010, 0.5 part of bis(2,5-dimethyl-2,5-di(tert-butylperoxy)hexane) and 0.5 part of erucamide by mass fraction, and place them in a high-speed mixer. Mix at a speed of 500 rpm for 10 minutes;

[0093] (3)Place the mixed materials in a twin-screw extruder for melt blending and extrusion granulation to obtain a special blending material; the extrusion temperature of the twin-screw extruder is 120 - 175 - 175 - 175 - 175 - 175 - 175 - 175 - 175 - 175 - 175 °C, the die head temperature is 160 °C, and the screw speed is 200 rpm;

[0094] (4)Put the obtained blended pellets into a bubble film casting machine for extrusion, traction, and winding to finally obtain a biodegradable bubble film; the extrusion temperature of the bubble film casting machine is 150 - 175 - 180 - 185 - 185 °C, the die head temperature is 200 - 195 - 190 - 185 - 185 - 190 - 195 - 200 °C, and the screw speed is 200 rpm.

[0095] Comparative Example 5

[0096] A biodegradable bubble film, and its preparation method includes the following steps:

[0097] (1)Vacuum dry PBAT, PLA, and modified PPC at 60 °C for 5 hours respectively;

[0098] (2)Weigh 68.0 parts of dried PBAT, 8.5 parts of PLA, 20.0 parts of modified PPC, 1.5 parts of bismaleimide, 0.5 part of antioxidant 168, 0.5 part of antioxidant 1010, 0.5 part of bis(2,5-dimethyl-2,5-di(tert-butylperoxy)hexane) and 0.5 part of erucamide by mass fraction, and place them in a high-speed mixer. Mix at a speed of 500 rpm for 10 minutes;

[0099] (3)Place the mixed materials in a twin-screw extruder for melt blending and extrusion granulation to obtain a special blending material; the extrusion temperature of the twin-screw extruder is 120 - 175 - 175 - 175 - 175 - 175 - 175 - 175 - 175 - 175 - 175 °C, the die head temperature is 160 °C, and the screw speed is 200 rpm;

[0100] (4) Put the obtained blended pellets into a bubble film casting machine for extrusion, traction, and winding to finally obtain a biodegradable bubble film; the extrusion temperature of the bubble film casting machine is 150 - 175 - 180 - 185 - 185 °C, the die head temperature is 200 - 195 - 190 - 185 - 185 - 190 - 195 - 200 °C, and the screw speed is 200 rpm.

[0101] Perform performance tests on the degradable bubble films obtained in the examples and comparative examples, and the test results are shown in Table 1.

[0102] Table 1 Performance test results of the degradable bubble films obtained in the examples and comparative examples

[0103]

[0104] Through the comparison of Examples 1 - 4, it can be found that in the blending system, when the PLA content remains unchanged, with the increase of the content of modified PPC, the tensile strength of the sample decreases significantly, and the elongation at break remains at a relatively high level. Therefore, to ensure that the film has a high tensile strength, the addition amount of modified PPC should be controlled to obtain a film material with good comprehensive performance. When the addition amount of modified PPC is 15%, the tensile strength of the film material shows the best performance.

[0105] Through the comparison of Example 3 and Comparative Example 1, it can be found that the degradable bubble film prepared with furan - group - modified polybutadiene liquid rubber has more advantages in mechanical properties and heat - seal strength than the degradable bubble film prepared with ordinary hydroxyl - terminated polybutadiene liquid rubber. This is because the polybutadiene liquid rubber with furan groups can form a cross - linked structure in the presence of bismaleimide, further increasing the entanglement density of molecular chains and improving the mechanical properties of the blending system.

[0106] Through the comparison of Example 3 with Comparative Examples 1 and 2, it can be found that PPC is a brittle material at room temperature. However, by using maleic anhydride for end - capping modification, the thermal stability and melt strength of PPC can be significantly improved, making it easy to process stably. Moreover, replacing ordinary PPC with maleic anhydride - end - capped modified PPC can significantly improve the mechanical properties of the obtained film. In addition, PPC is a material with good barrier properties. Adding a large amount of PPC under the premise of ensuring relatively high mechanical properties can improve the barrier properties of the biodegradable bubble film.

[0107] Through the comparison of Example 3 and Comparative Example 3, it can be found that when using PEG to replace the liquid polybutadiene rubber with furan groups, the tensile strength and elongation at break of the obtained film decrease significantly. This is because the compatibility between PEG and the polymer matrix is poor, and it is an unstable component during application, prone to precipitation, and difficult to meet the actual application requirements.

[0108] It can be found through the comparison between Example 3 and Comparative Examples 4 and 5 that when using only polybutadiene liquid rubber with a furan group as the branching agent or only using bismaleimide as the branching agent, the tensile strength and elongation at break of the film decrease significantly, proving that only when the two are used in combination can obvious advantages be exerted.

[0109] The above are only the preferred embodiments of the present invention, and all equivalent changes and modifications made according to the scope of the patent application of the present invention shall fall within the scope covered by the present invention.

Claims

1. A biodegradable bubble film, characterized in that, By mass parts, it includes the following components: 5-20 parts of modified PPC, 60-90 parts of PBAT, 5-20 parts of PLA, 0.1-5 parts of initiator, 0.1-5.0 parts of branching agent A, 0.1-5.0 parts of branching agent B, 0.2-1 part of antioxidant and 0.1-1 part of slip agent; The modified PPC is prepared by placing PPC and a capping agent in a high-speed mixer at a mass ratio of 100:0.5 for high-speed mixing, then adding the mixture into a twin-screw extruder for capping modification, and then through extrusion, strand drawing and pelletizing; the capping agent is maleic anhydride; The branching agent A is a polybutadiene liquid rubber with furan groups. It is prepared by first mixing hydroxyl-terminated polybutadiene liquid rubber and HDI at a molar ratio of 1:2 and reacting at 70 °C for 60 min to obtain isocyanate-capped polybutadiene liquid rubber, and then adding furfurylamine at a molar ratio of 2:1 to the isocyanate-capped polybutadiene liquid rubber and continuing the heat preservation reaction for 90 min; the molecular weight of the hydroxyl-terminated polybutadiene liquid rubber is 1000; The branching agent B is bismaleimide.

2. The biodegradable bubble film according to claim 1, wherein, The weight-average molecular weight of the PPC is 30-120 KDa; the rotation speed of the high-speed mixing is 300-1000 rpm, and the mixing time is 5-10 min; the extrusion temperature of the twin-screw extruder used is 120-175 °C, the die head temperature is 130-160 °C, and the screw rotation speed is 100-200 rpm.

3. A biodegradable bubble film according to claim 1, characterized in that, The weight-average molecular weight of the PBAT is 70-150 KDa; the weight-average molecular weight of the PLA is 160-300 KDa; the initiator is selected from one of bis(2,5-dimethyl-2,5-di(tert-butylperoxy)hexane) and DCP; the antioxidant is one or more of tea polyphenols, antioxidant 1076, antioxidant 1010 or antioxidant 168.

4. A biodegradable bubble film according to claim 1, wherein Its preparation includes the following steps: (1) Dry PBAT, PLA and modified PPC respectively; (2) Weigh the dried PBAT, PLA and modified PPC, and place them in a high-speed mixer together with the initiator, antioxidant, branching agent A, branching agent B and slip agent in proportion for high-speed mixing; (3) Place the mixed material in a twin-screw extruder for melt blending and extrusion granulation to obtain blended pellets; (4) Put the obtained blended pellets into a bubble film casting machine for extrusion, traction and winding to finally obtain the biodegradable bubble film.

5. A biodegradable bubble film according to claim 4, wherein, In step (2), the rotation speed of the high-speed mixing is 300-1000 rpm, and the mixing time is 5-10 min.

6. The biodegradable bubble film according to claim 4, characterized in that, In step (3), the extrusion temperature of the twin-screw extruder is 120-190 °C, the die head temperature is 130-160 °C, and the screw rotation speed is 100-300 rpm.

7. A biodegradable bubble film according to claim 4, wherein, In step (4), the extrusion temperature of the bubble film casting machine is 160-230 °C, the die head temperature is 180-230 °C, and the screw rotation speed is 50-200 rpm.

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