A bio-based high-barrier biaxially oriented polyester film with good toughness and a preparation method thereof

Abstract

The application discloses a kind of biobased high-barrier biaxially oriented polyester film with good toughness, which is composed of three-layer structure, from top to bottom in turn is upper surface layer, middle layer and lower surface layer, upper surface layer and lower surface layer are composed of the following raw materials by mass fraction: polyethylene 2,5-furan dicarboxylate 65-97.99 parts, nucleating agent 0.01-5 parts, toughening agent 1-20 parts, functional master batch 1-10 parts;The middle layer is composed of the following raw materials by mass fraction: polyethylene 2,5-furan dicarboxylate 75-98.99 parts, nucleating agent 0.01-5 parts, toughening agent 1-20 parts;Among them, the toughening agent is polyhydroxybutyrate copolymer;The application realizes good mutual coordination between film layers and formula through reasonable formula design and film layer structure design, realizes complementary advantages and strong combination between layers and formula, constitutes an organic whole that cannot be divided, and obtains a kind of biobased biaxially oriented polyester film with good toughness, good barrier property and high mechanical strength.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, and specifically relates to a bio-based high-barrier biaxially oriented polyester film with good toughness and its preparation method. Background Technology

[0002] After more than a century of development, polymers have become one of the most important material sources for modern human society. The raw materials for the preparation of traditional polymer materials mostly come from non-renewable petrochemical resources; common petroleum-based products include polyethylene, polypropylene, polyamide, and polyethylene terephthalate. With rapid global economic development and population growth, the consumption of petroleum-based resources is constantly increasing, making the demand for energy urgent. The use of polymers not only presents environmental problems during extraction and use but also leads to the excessive consumption of petroleum resources.

[0003] Bio-based resources refer to usable natural resources obtained from living organisms. Bio-based resources are of great importance to humans and the environment, and are widely used in food and agriculture, medicine, energy, and materials. Furthermore, bio-based resources are used to produce biofuels, bioplastics, and biochemicals—alternatives to traditional fossil fuels and chemical substances. Therefore, developing bio-based resources is beneficial to the sustainable development of the polymer industry, slowing the premature depletion of petroleum-based resources, protecting the environment, and reducing carbon emissions.

[0004] Polyethylene 2,5-furandicarboxylate (PEG) is a bio-based polyester. Compared to petroleum-based polyester PET, PEG has a higher glass transition temperature (Tg≈90℃). Due to the presence of the furan ring, it has a lower gas permeability coefficient for oxygen and carbon dioxide, resulting in significantly better gas barrier properties than PET. In terms of water vapor barrier properties, its water vapor permeability is also about one-third that of PET. Furthermore, PEG exhibits higher tensile strength and elastic modulus, and its mechanical properties are also superior to PET, making it a packaging material with excellent application prospects.

[0005] However, polyethylene 2,5-furandicarboxylate itself has poor toughness, and due to its low molecular symmetry and large intermolecular dipole interactions, the polymer's crystallization process is hindered, slowing down the crystallization rate and resulting in a long molding and processing cycle. Therefore, how to improve the material's toughness, shorten the processing cycle, and obtain a bio-based high-barrier biaxially oriented polyester film with good toughness has become an urgent problem to be solved. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides a bio-based high-barrier biaxially oriented polyester film with good toughness and its preparation method.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] A bio-based high-barrier biaxially oriented polyester film with good toughness is composed of a three-layer structure, consisting of an upper surface layer, a middle layer, and a lower surface layer from top to bottom. The upper and lower surface layers are composed of the following raw materials by mass: 65-97.99 parts of polyethylene 2,5-furandicarboxylate, 0.01-5 parts of nucleating agent, 1-20 parts of toughening agent, and 1-10 parts of functional masterbatch.

[0009] The intermediate layer, by weight, is composed of the following raw materials: 75-98.99 parts of polyethylene 2,5-furandicarboxylate, 0.01-5 parts of nucleating agent, and 1-20 parts of toughening agent;

[0010] The toughening agent is a polyhydroxybutyrate copolymer.

[0011] Furthermore, the polyhydroxybutyrate copolymer is a copolymer of 3β-hydroxybutyrate and 4β-hydroxybutyrate, wherein the molar proportion of 4β-hydroxybutyrate is 10%-65%.

[0012] Furthermore, the nucleating agent is a mixture of at least one of kaolin, titanium dioxide, boron nitride, sodium benzoate, lanthanum benzoate, and lanthanum cyclophosphate with graphene or montmorillonite at a mass ratio of 2:1.

[0013] Furthermore, the functional masterbatch, by mass parts, is composed of the following raw materials: 0.5-8 parts lubricant, 3-10 parts opening agent, 0.5-5 parts antioxidant, and 77-96 parts polyethylene 2,5-furandicarboxylate.

[0014] Furthermore, the lubricant is at least one of erucamide, oleamide, stearic acid, calcium stearate, magnesium stearate, barium stearate, PE wax, and modified ethylene bis-stearamide.

[0015] Furthermore, the opening agent is at least one of silicon dioxide, calcium carbonate, diatomaceous earth, and talc.

[0016] Furthermore, the antioxidant is at least one of phosphite antioxidants and phenolic antioxidants.

[0017] Furthermore, the functional masterbatch is obtained by melt extrusion, stranding, cooling, pelletizing and drying at 200-250°C using a twin-screw extruder.

[0018] Furthermore, the total thickness of the film is 10-80 μm; wherein the thickness of the upper and lower surface layers is 1-3 μm; and the thickness of the intermediate layer is 4-78 μm.

[0019] A method for preparing a bio-based high-barrier biaxially oriented polyester film with good toughness includes the following steps:

[0020] S1: Dry all raw materials and control the moisture content of the raw materials to be less than 100 ppm;

[0021] S2: Mix the raw materials of the upper surface layer, middle layer and lower surface layer according to the set ratio, disperse them evenly with a high-speed mixer, and then add them to the material bins of each extruder. They are then melted and plasticized at 200-250℃ through a twin-screw extruder and flow out through their respective T-die heads.

[0022] S3: Use a low-pressure air knife to attach the melt onto a cooling drum to form a thick sheet, wherein the thickness of the sheet is 120-850μm and the temperature of the cooling drum is 8-30℃;

[0023] S4: After heating the thick sheet, the bio-based polyester is simultaneously biaxially stretched using a synchronous biaxial stretching device, wherein the stretching temperature is 90-185℃ and the stretching ratio is (2.5-5.0)×(2.5-5.0).

[0024] S5: The stretched film undergoes heat setting at a temperature of 140-195℃ for 5-50 seconds. The film is then cooled and subjected to corona treatment before being wound up. The corona treatment power is 8-18 W / min / m. 2 ;

[0025] S6: The wound film is slit to obtain a bio-based high-barrier biaxially oriented polyester film with good toughness.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. This invention provides a bio-based high-barrier biaxially oriented polyester film with good toughness. Through reasonable formulation design and film layer structure design, the upper, middle, and lower layers of the film and the formulation achieve good mutual coordination and complementarity, forming an inseparable organic whole. This results in a bio-based biaxially oriented polyester film with good toughness, good barrier properties, and high mechanical strength. Furthermore, this invention uses bio-based materials, which can reduce carbon emissions, making it a green and environmentally friendly packaging material that conforms to the trend of environmental protection. This invention uses polyhydroxybutyrate copolymer as a toughening agent, which can greatly improve the toughness of the film and reduce the glass transition temperature of the material.

[0028] 2. In this invention, the toughening agent used is a polyhydroxybutyrate copolymer, which is a copolymer of 3β-hydroxybutyrate and 4β-hydroxybutyrate. Due to the different degrees of polymerization of the two monomers, 3β-hydroxybutyrate and 4β-hydroxybutyrate, an elastic change from brittle and hard to soft can be achieved. The molecular weight can be adjusted between tens of thousands and millions, the glass transition temperature can be as low as -50°C, and the tensile elongation at break can reach more than 200%. Due to the highly symmetrical molecular chains in polyethylene 2,5-furandicarboxylate and the presence of its polar oxygen and furan ring, it has very high rigidity and very poor toughness. The added polyhydroxybutyrate copolymer contains a large number of flexible groups. The addition of flexible groups can effectively reduce the intermolecular interaction and enhance the toughness and ductility of the material.

[0029] 3. In this invention, the nucleating agent used is at least one of kaolin, titanium dioxide, boron nitride, sodium benzoate, lanthanum benzoate, and lanthanum cyclophosphate mixed with graphene or montmorillonite in a mass ratio of 2:1. The layered structure of graphene and montmorillonite can improve the barrier properties of the film. By mixing the above raw materials as needed, crystal formation and growth can be promoted under a wider range of conditions, the nucleation efficiency can be improved, and the advantages of various nucleating agents can be combined to comprehensively improve the crystallization properties and surface properties of the film.

[0030] 4. The functional masterbatch used in this invention includes lubricant, opening agent, antioxidant, and polyethylene 2,5-furandicarboxylate. The functional masterbatch made from the above raw materials can reduce melt viscosity, improve the processing performance of the material, improve the physical properties of the film, and extend its service life. When added to the surface layer, it can give the film surface a non-stick and slippery property, thereby preventing the adhesion between layers.

[0031] 5. The present invention provides a method for preparing a bio-based high-barrier biaxially oriented polyester film with good toughness. The preparation process is simple, the production efficiency is high, and it is easy to industrialize. The film obtained has good toughness, good barrier properties, and high mechanical strength, and can be widely used in various packaging fields. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the structure of a bio-based high-barrier biaxially oriented polyester film with good toughness.

[0033] Figure 2 A flowchart illustrating a method for preparing a bio-based high-barrier biaxially oriented polyester film with good toughness;

[0034] Among them, 30 is the upper surface layer; 20 is the middle layer; and 10 is the lower surface layer. Detailed Implementation

[0035] The following describes a preferred embodiment, with reference to the appendix. Figure 1 To further illustrate the present invention, the endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values; for numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be considered as specifically disclosed herein; the materials, reagents, etc. used in the following embodiments are commercially available unless otherwise specified; the experimental methods in the following embodiments are conventional methods unless otherwise specified.

[0036] Example 1

[0037] This embodiment provides a bio-based high-barrier biaxially oriented polyester film with good toughness, such as... Figure 1 As shown, it consists of a three-layer structure, from top to bottom: an upper surface layer 30, a middle layer 20, and a lower surface layer 10. The upper surface layer 30 and the lower surface layer 10 are composed of the following raw materials by mass percentage:

[0038] Table 1. Components of the upper and lower surface layers

[0039] Polyethylene 2,5-furandicarboxylate 83 copies nucleating agent 2 copies toughening agent 10 copies Functional Masterbatch 5 copies

[0040] The intermediate layer 20 is composed of the following raw materials by weight:

[0041] Table 2 Intermediate layer composition

[0042] Polyethylene 2,5-furandicarboxylate 88 copies nucleating agent 2 copies toughening agent 10 copies

[0043] This embodiment achieves excellent coordination and cooperation among the upper, middle, and lower layers of the film and the formulation through reasonable formulation design and film layer structure design. It also enables each layer and formulation to complement each other and form an inseparable organic whole, resulting in a bio-based biaxially oriented polyester film with good toughness, good barrier properties, and high mechanical strength. Furthermore, the polyethylene 2,5-furandicarboxylate used in this embodiment is a bio-based material, which can reduce carbon emissions and is a green and environmentally friendly packaging material that conforms to the trend of environmental protection.

[0044] In this embodiment, the toughening agent used is a polyhydroxybutyrate copolymer, which is also a bio-based material. The polyhydroxybutyrate copolymer is a copolymer of 3β-hydroxybutyrate and 4β-hydroxybutyrate, with the 4β-hydroxybutyrate accounting for 30% of the molar ratio. The polyhydroxybutyrate copolymer used in this embodiment can achieve an elastic change from brittle and hard to soft, and the molecular weight can be adjusted between tens of thousands and millions. The glass transition temperature can be as low as -50°C, and the tensile elongation at break can reach more than 200%, which can greatly improve the toughness of the film.

[0045] In this embodiment, the nucleating agent used is a mixture of sodium benzoate and graphene in a mass ratio of 2:1. The addition of sodium benzoate and graphene not only accelerates the nucleation rate and shortens the processing cycle, but the sheet structure of graphene can also enhance the barrier properties of the film and prevent the penetration of substances such as water, oxygen, and gases.

[0046] The functional masterbatch used in this embodiment is composed of the following raw materials by weight: 5 parts erucamide, 8 parts silica, 3 parts antioxidant, and 84 parts polyethylene 2,5-furandicarboxylate. The functional masterbatch made from the above raw materials can not only reduce melt viscosity and improve the processing performance of materials, but also improve the physical properties of films and extend their service life. When added to the surface layer, it can give the film surface a non-stick and slippery property, thereby preventing the adhesion between layers.

[0047] The antioxidants used are phosphites, tris[2,4-di-tert-butylphenyl]phosphite and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] in a 1:2 ratio.

[0048] In this embodiment, the functional masterbatch is obtained by melt extrusion, stranding, cooling, pelletizing and drying at 225°C using a twin-screw extruder.

[0049] This embodiment also provides a method for preparing a bio-based high-barrier biaxially oriented polyester film with good toughness, including the following steps:

[0050] S1: Dry all raw materials and control the moisture content of the raw materials to be less than 100 ppm;

[0051] S2: Mix the raw materials of the upper surface layer 30, the middle layer 20 and the lower surface layer 10 according to the set ratio, disperse them evenly using a high-speed mixer, and then add them to the material bins of each extruder. They are then melted and plasticized at 225°C through a twin-screw extruder and flow out through their respective T-die heads.

[0052] S3: Use a low-pressure air knife to attach the melt onto a cooling drum to form a thick sheet, wherein the thickness of the sheet is 180μm and the temperature of the cooling drum is 20℃;

[0053] S4: After heating the thick sheet, the bio-based polyester is simultaneously biaxially stretched using a synchronous biaxial stretching device, wherein the stretching temperature is 138℃ and the stretching ratio is 3.4×3.4.

[0054] S5: The stretched film undergoes heat setting at 175℃ for 12 seconds. Afterward, the film is cooled, subjected to corona treatment, and then wound up. The corona treatment power is 12 W / min / m. 2 ;

[0055] S6: The wound film is slit to obtain a bio-based high-barrier biaxially oriented polyester film with good toughness.

[0056] This embodiment provides a method for preparing a bio-based high-barrier biaxially oriented polyester film with good toughness. The preparation process is simple, the production efficiency is high, and it is easy to industrialize. The film obtained has good toughness, good barrier properties, and high mechanical strength, and can be widely used in various packaging fields.

[0057] The total thickness of the bio-based high-barrier biaxially oriented polyester film with good toughness prepared according to the above method is 15 μm, the thickness of the upper surface layer 30 and the lower surface layer 10 is 2 μm, and the thickness of the intermediate layer 20 is 11 μm.

[0058] Example 2

[0059] This embodiment provides a bio-based high-barrier biaxially oriented polyester film with good toughness. Its specific structure is the same as that of Embodiment 1, except that the raw material combination of the upper and lower surface layers is different.

[0060] The upper and lower surface layers, by mass fraction, are composed of the following raw materials:

[0061] Table 3 Components of the upper and lower surface layers

[0062] Polyethylene 2,5-furandicarboxylate 90.5 copies nucleating agent 0.5 copies toughening agent 6 copies Functional Masterbatch 3 copies

[0063] The intermediate layer, by weight, is composed of the following raw materials:

[0064] Table 4. Intermediate layer composition

[0065] Polyethylene 2,5-furandicarboxylate 93.5 copies nucleating agent 0.5 copies toughening agent 6 copies

[0066] In this embodiment, the toughening agent used is a polyhydroxybutyrate copolymer, which is a copolymer of 3β-hydroxybutyrate and 4β-hydroxybutyrate, and the 4β-hydroxybutyrate accounts for 15% of the molar ratio.

[0067] In this embodiment, the nucleating agent used is a mixture of lanthanum cyclic phosphate and montmorillonite in a mass ratio of 2:1.

[0068] The functional masterbatch used in this embodiment is composed of the following raw materials by mass: 3 parts modified ethylene bis-stearamide, 8 parts silica, 2 parts antioxidant, and 87 parts polyethylene 2,5-furandicarboxylate.

[0069] The antioxidants used are phosphites, tris[2,4-di-tert-butylphenyl]phosphite and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] in a 1:2 ratio.

[0070] In this embodiment, the functional masterbatch is obtained by melt extrusion, stranding, cooling, pelletizing and drying at 230°C using a twin-screw extruder.

[0071] This embodiment also provides a method for preparing a bio-based high-barrier biaxially oriented polyester film with good toughness, including the following steps:

[0072] S1: Dry all raw materials and control the moisture content of the raw materials to be less than 100 ppm;

[0073] S2: Mix the raw materials of the upper surface layer, middle layer and lower surface layer according to the set ratio, disperse them evenly with a high-speed mixer, and then add them to the material bins of each extruder. They are then melted and plasticized at 230°C through a twin-screw extruder and flow out through their respective T-die heads.

[0074] S3: Use a low-pressure air knife to attach the melt onto a cold drum to form a thick sheet, wherein the thickness of the sheet is 210μm and the temperature of the cold drum is 10℃;

[0075] S4: After heating the thick sheet, the bio-based polyester is simultaneously biaxially stretched using a synchronous biaxial stretching device, wherein the stretching temperature is 135℃ and the stretching ratio is 3.2×3.2.

[0076] S5: The stretched film undergoes heat setting at 180℃ for 20 seconds. Afterward, the film is cooled, subjected to corona treatment, and then wound up. The corona treatment power is 10 W / min / m. 2 ;

[0077] S6: The wound film is slit to obtain a bio-based high-barrier biaxially oriented polyester film with good toughness.

[0078] The total thickness of the bio-based high-barrier biaxially oriented polyester film with good toughness prepared according to the above method is 20 μm, the thickness of the upper and lower surface layers is 1.5 μm, and the thickness of the intermediate layer is 17 μm.

[0079] Example 3

[0080] This embodiment provides a bio-based high-barrier biaxially oriented polyester film with good toughness. Its specific structure is the same as that of Embodiment 1, except that the raw material combination of the upper and lower surface layers is different.

[0081] The upper and lower surface layers, by mass fraction, are composed of the following raw materials:

[0082] Table 5. Components of the upper and lower surface layers

[0083] Polyethylene 2,5-furandicarboxylate 73 copies nucleating agent 4 copies toughening agent 15 copies Functional Masterbatch 8 copies

[0084] The intermediate layer, by weight, is composed of the following raw materials:

[0085] Table 6. Intermediate layer composition

[0086] Polyethylene 2,5-furandicarboxylate 73 copies nucleating agent 4 copies toughening agent 8 copies

[0087] In this embodiment, the toughening agent used is a polyhydroxybutyrate copolymer, which is a copolymer of 3β-hydroxybutyrate and 4β-hydroxybutyrate, and the 4β-hydroxybutyrate accounts for 50% of the molar ratio.

[0088] In this embodiment, the nucleating agent used is a mixture of boron nitride and graphene in a mass ratio of 2:1.

[0089] The functional masterbatch used in this embodiment is composed of the following raw materials by mass: 5 parts erucamide, 8 parts silica, 3 parts antioxidant, and 84 parts polyethylene 2,5-furandicarboxylate.

[0090] The antioxidants used are phosphites, tris[2,4-di-tert-butylphenyl]phosphite and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] in a 1:2 ratio.

[0091] In this embodiment, the functional masterbatch is obtained by melt extrusion, stranding, cooling, pelletizing and drying using a twin-screw extruder at 235°C.

[0092] This embodiment also provides a method for preparing a bio-based high-barrier biaxially oriented polyester film with good toughness, including the following steps:

[0093] S1: Dry all raw materials and control the moisture content of the raw materials to be less than 100 ppm;

[0094] S2: Mix the raw materials of the upper surface layer, middle layer and lower surface layer according to the set ratio, disperse them evenly with a high-speed mixer, and then add them to the material bins of each extruder. They are then melted and plasticized at 235°C through a twin-screw extruder and flow out through their respective T-die heads.

[0095] S3: Use a low-pressure air knife to attach the melt onto a cooling drum to form a thick sheet, wherein the thickness of the sheet is 135μm and the temperature of the cooling drum is 25℃;

[0096] S4: After heating the thick sheet, the bio-based polyester is simultaneously biaxially stretched using a synchronous biaxial stretching device, wherein the stretching temperature is 150℃ and the stretching ratio is 3.3×3.3.

[0097] S5: The stretched film undergoes heat setting at 188℃ for 30 seconds. Afterward, the film is cooled, subjected to corona treatment, and then wound up. The corona treatment power is 12 W / min / m. 2 ;

[0098] S6: The wound film is slit to obtain a bio-based high-barrier biaxially oriented polyester film with good toughness.

[0099] The total thickness of the bio-based high-barrier biaxially oriented polyester film with good toughness prepared by the above method is 12 μm, the thickness of the upper and lower surface layers is 1.5 μm, and the thickness of the intermediate layer is 9 μm.

[0100] In addition, the nucleating agent in this invention can also be obtained by mixing several of the following: kaolin, titanium dioxide, boron nitride, sodium benzoate, lanthanum benzoate, and cyclolanthanum phosphate with graphene or montmorillonite in a mass ratio of 2:1; the lubricant in the functional masterbatch can also be selected from several combinations of erucamide, oleamide, stearic acid, calcium stearate, magnesium stearate, barium stearate, PE wax, and modified ethylene bis-stearamide; the opening agent in the functional masterbatch can also be selected from several combinations of silica, calcium carbonate, diatomaceous earth, and talc; and the antioxidant in the functional masterbatch can also be selected from several combinations of phosphite antioxidants and phenolic antioxidants.

[0101] Comparative Example 1

[0102] The difference from Example 1 is as follows:

[0103] The upper and lower surface layers, by mass, are composed of the following raw materials:

[0104] Table 7 Components of the upper and lower surface layers

[0105] Polyethylene 2,5-furandicarboxylate 95 copies Functional Masterbatch 5 copies

[0106] The intermediate layer is made of 100 parts of polyethylene 2,5-furandicarboxylate.

[0107] The functional masterbatch used in this comparative example is composed of the following raw materials by mass: 5 parts erucamide, 8 parts silica, 3 parts antioxidant, and 84 parts polyethylene 2,5-furandicarboxylate.

[0108] The antioxidants used are phosphites, tris[2,4-di-tert-butylphenyl]phosphite and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] in a 1:2 ratio;

[0109] In this comparative example, the functional masterbatch was obtained by melt extrusion, stranding, cooling, pelletizing and drying using a twin-screw extruder at 225°C.

[0110] Comparative Example 2

[0111] The difference from Example 1 is as follows:

[0112] The upper and lower surface layers, by mass, are composed of the following raw materials:

[0113] Table 8. Components of the upper and lower surface layers

[0114] Polyethylene 2,5-furandicarboxylate 93 copies nucleating agent 2 copies Functional Masterbatch 5 copies

[0115] The intermediate layer, by weight, consists of the following raw materials:

[0116] Table 9. Intermediate Layer Components

[0117] Polyethylene 2,5-furandicarboxylate 98 copies nucleating agent 2 copies

[0118] In this comparative example, the nucleating agent used was a mixture of sodium benzoate and graphene in a mass ratio of 2:1.

[0119] The functional masterbatch used in this comparative example is composed of the following raw materials by mass: 5 parts erucamide, 8 parts silica, 3 parts antioxidant, and 84 parts polyethylene 2,5-furandicarboxylate.

[0120] The antioxidants used are phosphites, tris[2,4-di-tert-butylphenyl]phosphite and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] in a 1:2 ratio;

[0121] In this comparative example, the functional masterbatch was obtained by melt extrusion, stranding, cooling, pelletizing and drying using a twin-screw extruder at 225°C.

[0122] Comparative Example 3

[0123] The difference from Example 1 is as follows:

[0124] The upper and lower surface layers, by mass, are composed of the following raw materials:

[0125] Table 10 Components of the upper and lower surface layers

[0126] Polyethylene 2,5-furandicarboxylate 85 copies toughening agent 10 copies Functional Masterbatch 5 copies

[0127] The intermediate layer, by weight, consists of the following raw materials:

[0128] Table 11 Intermediate Layer Components

[0129] Polyethylene 2,5-furandicarboxylate 90 copies toughening agent 10 copies

[0130] In this comparative example, the toughening agent used is a polyhydroxybutyrate copolymer, which is a copolymer of 3β-hydroxybutyrate and 4β-hydroxybutyrate, and the molar proportion of 4β-hydroxybutyrate is 30%.

[0131] The functional masterbatch used in this comparative example is composed of the following raw materials by mass: 5 parts erucamide, 8 parts silica, 3 parts antioxidant, and 84 parts polyethylene 2,5-furandicarboxylate.

[0132] The antioxidants used are phosphites, tris[2,4-di-tert-butylphenyl]phosphite and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] in a 1:2 ratio;

[0133] In this comparative example, the functional masterbatch was obtained by melt extrusion, stranding, cooling, pelletizing and drying using a twin-screw extruder at 225°C.

[0134] Comparative Example 4

[0135] The difference from Example 1 is as follows:

[0136] The upper and lower surface layers, by mass, are composed of the following raw materials:

[0137] Table 12 Components of the upper and lower surface layers

[0138] Polyethylene 2,5-furandicarboxylate 83 copies nucleating agent 2 copies toughening agent 10 copies Functional Masterbatch 5 copies

[0139] The intermediate layer, by weight, consists of the following raw materials:

[0140] Table 13 Intermediate Layer Components

[0141] Polyethylene 2,5-furandicarboxylate 88 copies nucleating agent 2 copies toughening agent 10 copies

[0142] In this comparative example, the toughening agent used is a polyhydroxybutyrate copolymer, which is a copolymer of 3β-hydroxybutyrate and 4β-hydroxybutyrate, and the molar proportion of 4β-hydroxybutyrate is 30%.

[0143] In this comparative example, the nucleating agent used was sodium benzoate;

[0144] The functional masterbatch used in this comparative example is composed of the following raw materials by mass: 5 parts erucamide, 8 parts silica, 3 parts antioxidant, and 84 parts polyethylene 2,5-furandicarboxylate.

[0145] The antioxidants used are phosphites, tris[2,4-di-tert-butylphenyl]phosphite and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] in a 1:2 ratio;

[0146] In this comparative example, the functional masterbatch was obtained by melt extrusion, stranding, cooling, pelletizing and drying using a twin-screw extruder at 225°C.

[0147] Implementation effectiveness evaluation:

[0148] The following specific experiments on the bio-based high-barrier biaxially oriented polyester films with good toughness prepared in Examples 1-3 and Comparative Examples 1-4 further illustrate the excellent effects achieved by the present invention:

[0149] Tensile strength and elongation at break tests: The tests were conducted in accordance with GB / T 1040.3 "Standard requirements for determination of tensile properties of plastics";

[0150] Dart impact strength test: The test shall be conducted in accordance with the requirements of GB / T 9639.1 "Test method for impact resistance of plastic films and sheets";

[0151] Thickness performance testing: The test shall be conducted in accordance with the requirements of GB / T 6672 "Determination of thickness of plastic films and sheets: Mechanical measurement method";

[0152] Barrier performance testing: The test was conducted in accordance with the requirements of ASTM D3985, "Standard Test Method for Oxygen Gas Transmission Rate Through Plastic Film and Sheeting Using a Coulometric Sensor".

[0153] The test results are shown in the table below:

[0154] Table 14 Statistical Table of Test Results

[0155]

[0156] In this symbol, “◎” indicates excellent, “□” indicates good, “△” indicates average, and “×” indicates poor.

[0157] As can be seen from the table above, the bio-based high-barrier biaxially oriented polyester film with good toughness provided by the present invention has good toughness, good barrier properties, and excellent mechanical properties.

[0158] The test results of Example 1 and Comparative Examples 1-3 show that the nucleating agent used in this invention has a certain barrier property and helps to improve the tensile strength of the film; the toughening agent used can greatly improve the toughness of the film.

[0159] The test results of Example 1 and Comparative Example 4 show that the nucleating agent obtained by mixing at least one of kaolin, titanium dioxide, boron nitride, sodium benzoate, lanthanum benzoate, and lanthanum cyclophosphate with graphene or montmorillonite in a mass ratio of 2:1 can improve the barrier properties and mechanical properties of the film, as well as the flexibility of the film.

[0160] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A bio-based high-barrier biaxially oriented polyester film with good toughness, comprising a three-layer structure, consisting of an upper surface layer, a middle layer, and a lower surface layer from top to bottom, characterized in that, The upper and lower surface layers, by mass fraction, are composed of the following raw materials: 65-97.99 parts of polyethylene 2,5-furandicarboxylate, 0.01-5 parts of nucleating agent, 1-20 parts of toughening agent, and 1-10 parts of functional masterbatch. The intermediate layer, by weight, is composed of the following raw materials: 75-98.99 parts of polyethylene 2,5-furandicarboxylate, 0.01-5 parts of nucleating agent, and 1-20 parts of toughening agent; The toughening agent is a polyhydroxybutyrate copolymer; The polyhydroxybutyrate copolymer is a copolymer of 3β-hydroxybutyrate and 4β-hydroxybutyrate, wherein the molar proportion of 4β-hydroxybutyrate is 10%-65%. The nucleating agent is a mixture of at least one of kaolin, titanium dioxide, boron nitride, sodium benzoate, lanthanum benzoate, and lanthanum cyclophosphate with graphene or montmorillonite in a mass ratio of 2:

1. The functional masterbatch, by weight, is composed of the following raw materials: 0.5-8 parts lubricant, 3-10 parts opening agent, 0.5-5 parts antioxidant, and 77-96 parts polyethylene 2,5-furandicarboxylate.

2. The bio-based high-barrier biaxially oriented polyester film with good toughness according to claim 1, characterized in that, The lubricant is at least one of erucamide, oleamide, stearic acid, calcium stearate, magnesium stearate, barium stearate, PE wax, and modified ethylene bis-stearamide.

3. The bio-based high-barrier biaxially oriented polyester film with good toughness according to claim 1, characterized in that, The opening agent is at least one of silicon dioxide, calcium carbonate, diatomaceous earth, and talc.

4. The bio-based high-barrier biaxially oriented polyester film with good toughness according to claim 1, characterized in that, The antioxidant is at least one of phosphite antioxidants and phenolic antioxidants.

5. A bio-based high-barrier biaxially oriented polyester film with good toughness according to claim 1, characterized in that, The functional masterbatch is obtained by melt extrusion, stranding, cooling, pelletizing and drying in a twin-screw extruder at 200-250°C.

6. The bio-based high-barrier biaxially oriented polyester film with good toughness according to claim 1, characterized in that, The total thickness of the film is 10-80 μm; the thickness of the upper and lower surface layers is 1-3 μm; and the thickness of the intermediate layer is 4-78 μm.

7. A method for preparing a bio-based high-barrier biaxially oriented polyester film with good toughness according to any one of claims 1-6, characterized in that, Includes the following steps: S1: Dry all raw materials and control the moisture content of the raw materials to be less than 100 ppm; S2: Mix the raw materials of the upper surface layer, middle layer and lower surface layer according to the set ratio, disperse them evenly with a high-speed mixer, and then add them to the material bins of each extruder. They are then melted and plasticized at 200-250℃ through a twin-screw extruder and flow out through their respective T-die heads. S3: Use a low-pressure air knife to attach the melt onto a cooling drum to form a thick sheet, wherein the thickness of the sheet is 120-850μm and the temperature of the cooling drum is 8-30℃; S4: After heating the thick sheet, the bio-based polyester is simultaneously biaxially stretched using a synchronous biaxial stretching device, wherein the stretching temperature is 90-185℃ and the stretching ratio is (2.5-5.0)×(2.5-5.0). S5: The stretched film is heat-set at a temperature of 140-195℃ for 5-50 seconds. The film is then cooled and corona-treated before being wound up. The corona treatment power is 8-18Wmin / m². S6: The wound film is slit to obtain a bio-based high-barrier biaxially oriented polyester film with good toughness.

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