A high-performance biodegradable film and its preparation method and application

Abstract

The present invention relates to a high-performance biodegradable film, a preparation method thereof, and an application thereof. The biodegradable film comprises a barrier layer and protective layers located on both sides of the barrier layer. The raw materials of the barrier layer comprise barrier layer biodegradable polyester, an additive A, an additive B, and an additive C; the raw materials of the protective layer comprise protective layer biodegradable polyester, an additive A, an additive B, and an additive C; the barrier layer biodegradable polyester and the protective layer biodegradable polyester have at least one of the same type of biodegradable polyester. The present invention has no adhesive layer, a tensile strength of 20-100 MPa, and a water vapor permeability coefficient of 1 g·mil / (m 2 ·day·kPa), the oxygen permeability coefficient can reach 0.25cc·mil / (m 2 ·day·atm), it can be completely degraded in 3-6 months under industrial composting conditions and is processed using three-layer co-extrusion or three-layer co-blowing equipment.

Description

Technical Field

[0001] The present invention relates to the field of packaging films, and in particular to a high-performance biodegradable film and a preparation method and application thereof. Background Art

[0002] There are three main types of barrier packaging films: the first type is organic composite film, which uses polyamide, polyvinylidene chloride, and polyvinylidene chloride as barrier layers, and multi-layer composite films with polyethylene, polypropylene, polystyrene, etc. This type of packaging film is non-degradable and produces white pollution; the second type is aluminum foil or film aluminum as a barrier layer. The process of this barrier film is relatively simple, and the barrier properties to air and moisture are also very high. Using pure aluminum foil for packaging can greatly improve the barrier properties. The aluminum foil requires a certain thickness, which increases the packaging cost. The energy consumption in the aluminum production process is large, and large-scale use leads to the depletion of natural resources, difficulties in recycling, and environmental pollution, which runs counter to the current green packaging; the third type is the surface of the organic film through thermal chemical vapor deposition of metal oxides or silicon oxide, silicon nitride, silicon oxynitride, etc. The high-barrier oxide film deposited on the surface is firmly bonded to the plastic base film, which is difficult to recycle, non-degradable, and pollutes the environment.

[0003] Given this, biodegradable materials are expected to address the aforementioned issues and have become a research hotspot in the barrier packaging film field. Patent publication number CN 102029754 A provides a high-barrier co-extruded stretch film, primarily composed of polyolefins and / or polyvinylidene chloride and polyamide. This type of film is non-degradable after use and disposal, easily causing white pollution and harming the environment. Patent publication number CN101692777A provides a plant fiber mulch film that utilizes plant fibers from various sources using a physical method similar to papermaking, including raw material preparation, slurry preparation, and fiber film formation. This type of mulch film degrades quickly, but is thicker and has poor barrier properties, resulting in poor thermal insulation and moisture retention. Patent publication number CN 115891365 A discloses a degradable barrier film with antibacterial properties and a controllable degradation rate, and a method for preparing the same. The degradable barrier film comprises a three-layer co-extruded film, comprising, from the outside to the inside, a first polylactic acid layer, a second polyglycolic acid layer, and a third polybutylene terephthalate adipate layer. This ensures that the degradable barrier film maintains long-lasting barrier properties during normal use while also ensuring rapid degradation after use, thereby achieving controllable degradation of the degradable barrier film. However, the interlayer adhesion of this three-layer composite film is poor, making it prone to interlayer separation. Such delamination or integrity loss is unacceptable during the service life of the multilayer film. Patent publication number CN 116512721 A provides a biodegradable multilayer high-barrier film, its preparation method, and application. The multilayer high-barrier film comprises: an outer layer / adhesive layer / barrier layer / adhesive layer / outer layer arranged in this order; the outer layer comprises a resin blend I of polybutylene terephthalate adipate, polyglycolic acid, and a compatibilizer; the adhesive layer comprises a resin blend II of polybutylene terephthalate adipate, polyglycolic acid, and a compatibilizer; and the barrier layer comprises polyglycolic acid. This invention uses polyglycolic acid as the barrier layer, but its adhesion to the outer layer is poor, requiring two adhesive layers to improve interlayer adhesion. The production equipment for this five-layer composite film is expensive and the process is complex. Patent publication number WO2023052144A1 provides biodegradable laminated films and containers made therefrom. The biodegradable laminated films have a layer structure A / B, wherein the 0.5 to 7 μm thick layer A comprises a polyurethane or acrylate adhesive, and the 5 to 150 μm thick layer B comprises an aliphatic polyester and / or an aliphatic-aromatic polyester. The multilayer laminated film process, with adhesive layers between the layers, provides good adhesion, but the production process is complex and the production cost is high.

[0004] Therefore, how to further improve the film with biodegradable, high strength, high barrier properties and easy production and processing becomes a research direction. In view of this, the present invention provides a high-performance biodegradable film and its preparation method and application. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a high-performance biodegradable film, a preparation method thereof, and applications thereof. The purpose is to provide a biodegradable film that is biodegradable, has high strength, strong adhesion, and excellent barrier properties, a preparation method thereof, and applications thereof.

[0006] The technical solution of the present invention to solve the above technical problems is as follows:

[0007] In a first aspect, a high-performance biodegradable film is provided, comprising a barrier layer and protective layers located on both sides of the barrier layer, wherein the raw materials of the barrier layer comprise barrier layer biodegradable polyester, additive A, additive B, and additive C; the raw materials of the protective layer comprise protective layer biodegradable polyester, additive A, additive B, and additive C; the barrier layer biodegradable polyester and the protective layer biodegradable polyester have at least one of the same type of biodegradable polyester.

[0008] The beneficial effects of the present invention are as follows: the present invention has the following advantages: (1) no adhesive layer: the adhesive force between the layers is increased by adding an adhesive to the formulation system; (2) high strength: the tensile strength is 20-100 MPa; (3) high barrier: the water vapor permeability coefficient can reach 1g·mil / (m 2 ·day·kPa), the oxygen permeability coefficient can reach 0.25cc·mil / (m 2 ·day·atm); (4) Biodegradation: Under industrial composting conditions, it can be completely degraded in 3-6 months; (5) Easy to process: It can be processed by three-layer co-extrusion or three-layer co-blowing equipment.

[0009] On the basis of the above technical solution, the present invention can also be improved as follows.

[0010] Further, the biodegradable polyester of the barrier layer includes at least one of polyglycolic acid, polylactic acid, polyhydroxybutyrate, polyhydroxyvalerate, polybutylene terephthalate adipate, polybutylene succinate, polybutylene succinate-co-butylene terephthalate, polybutylene succinate adipate, polycaprolactone, polypropylene carbonate, polyhydroxybutyrate-co-hydroxyvalerate, poly 3-hydroxybutyrate-co-4-hydroxybutyrate, polyhydroxybutyrate caproate, and polylactic acid-co-glycolic acid; and / or

[0011] The biodegradable polyester of the protective layer comprises at least one of polyglycolic acid, polylactic acid, polyhydroxybutyrate, polyhydroxyvalerate, polybutylene terephthalate adipate, polybutylene succinate, polybutylene succinate-co-butylene terephthalate, polybutylene succinate adipate, polycaprolactone, polypropylene carbonate, polyhydroxybutyrate-co-hydroxyvalerate, poly 3-hydroxybutyrate-co-4-hydroxybutyrate, polyhydroxybutyrate caproate, and polylactic acid-co-glycolic acid; and / or

[0012] The auxiliary agent A includes at least one of ethylene-acrylate-glycidyl methacrylate, ethylene-methacrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-butyl acrylate copolymer, silane coupling agent (silane coupling agent, for example, KH151, KH550, KH560, KH570, KH580, KH171, A171, A172, A173, A174, KBM603, MP1200, etc.), titanate coupling agent, and aluminate coupling agent; and / or

[0013] The auxiliary agent B includes at least one of a chain extender, a plasticizer, a lubricant, an anti-blocking agent, an antioxidant, an anti-hydrolysis agent, and a light stabilizer; and / or

[0014] The auxiliary agent C includes at least one of an organic filler and an inorganic filler.

[0015] Further, the chain extender includes at least one of 1,4-butane diisocyanate, toluene diisocyanate, hexamethylene diisocyanate, octadecyl isocyanate, polymethylene polyphenyl polyisocyanate, diphenylmethane diisocyanate, lysine diisocyanate, polyisocyanate, Joncryl ADR series (Joncryl ADR series can be BASF's Joncryl ADR series, such as ADR4300, ADR4400, ADR 4370S, ADR4368, ADR4468, ADR4400F, etc.), maleic anhydride, phthalic anhydride, hexanoic anhydride, cyclohexanecarboxylic anhydride, succinic anhydride, polyol, polyacid, polyamine (polyamines such as triethylenetetramine, dimethylaminopropylamine, diethylaminopropylamine, propylenediamine, polyethylene glycol, polypropylene glycol and trimethylolpropane, etc.); and / or

[0016] The plasticizer comprises at least one of tributyl citrate, triethyl citrate, citric acid, glycerol, diethylene glycol, triacetin, dioctyl phthalate, ethylene glycol, propylene glycol, sorbitol, pentaerythritol, acetyl tributyl citrate, epoxy soybean oil, propylene glycol adipate, diisononyl adipate, dioctyl maleate, polypropylene glycol, polyethylene glycol, and acetylated monoglycerol fatty acid ester; and / or

[0017] The lubricant comprises at least one of polyethylene wax, stearic acid, pentaerythritol stearate, calcium stearate, magnesium stearate, zinc stearate, ferrous stearate, and dihydroxypropyl octadecanoic acid; and / or

[0018] The opening agent comprises at least one of silicon dioxide, talc, calcium carbonate, N,N'-ethylenebisstearamide, oleamide, erucamide and silicone; and / or

[0019] The antioxidant comprises at least one of BASF Irganox 168, 1010, 245, 1024, 1076, 1098, 3114, MD 1024, 1025, ADEKA AO-60, 80, STAB PEP-36, 8T, Albemarle AT-10, 245, 330, 626, 702, 733, 816, 1135; and / or

[0020] The anti-hydrolysis agent includes at least one of triethyl phosphite, dihydroxypropyl octadecanoic acid, a polycarbodiimide compound, a monocarbodiimide compound, and a bis-monocarbodiimide compound, preferably bis(2,6-diisopropylphenyl)carbodiimide; and / or

[0021] The light stabilizer includes at least one of UV-531, UV-329, UV-326, UV-328, UV-360, UV-P, UV-234, UV-1130, UV-384-2, UV-928, UV-400, UV-405, UV-1577, UV-1164, UV-123, UV-292, UV-622, UV-770, and UV-944; and / or

[0022] The organic filler comprises at least one of starch, carboxymethyl starch, pregelatinized starch, dialdehyde starch, phosphate starch, hydroxypropyl distarch phosphate, bamboo powder, cellulose, hydroxypropyl methylcellulose, ethyl cellulose, polyanionic cellulose, hydroxyethyl cellulose, microcrystalline cellulose, cellulose nano whiskers, lignin, chitosan, and chitin; and / or

[0023] The inorganic filler includes at least one of talc, diatomaceous earth, kaolin, calcium carbonate, barium sulfate, glass fiber, glass beads, nanoclay, carbon black, carbon fiber, carbon nanotubes, graphene, titanium dioxide, silicon dioxide, hydrotalcite, titanium dioxide, mica powder, zinc sulfide, zinc oxide, calcium oxide, montmorillonite, steel fiber, hemp fiber, bamboo fiber, wood fiber, wood powder, wood chips, aluminum oxide, magnesium oxide, zinc oxide, aluminum nitride, boron nitride, silicon carbide, graphite, silicon carbide, potassium titanate, aluminum borate, calcium sulfate, magnesium sulfate, ceramic whiskers, inorganic salt whiskers, and metal whiskers.

[0024] Furthermore, the thickness of the biodegradable film is 5-1000 μm, preferably 20-800 μm, more preferably 30-500 μm; the thickness of the barrier layer is 3-800 μm, preferably 10-500 μm, more preferably 30-300 μm; the thickness of the protective layer is 800-2 μm, preferably 500-10 μm, more preferably 300-30 μm.

[0025] Furthermore, the tensile strength of the biodegradable film is greater than 15 MPa, preferably greater than 25 MPa, more preferably greater than 30 MPa; the interlayer peel strength between the barrier layer and the protective layer is greater than or equal to 1.5 N / 15 mm, preferably greater than or equal to 2 N / 15 mm, more preferably greater than or equal to 2.5 N / 15 mm; the oxygen permeability coefficient of the biodegradable film is less than or equal to 300 cc · mil / (m 2 · day · atm), preferably less than or equal to 100cc · mil / (m 2 · day · atm), more preferably less than or equal to 10 cc · mil / (m 2 · day · atm); the water vapor permeability coefficient of the biodegradable film is less than or equal to 400g · mil / (m 2 · day · kPa), preferably less than or equal to 100g · mil / (m 2 · day · kPa), more preferably less than or equal to 5g · mil / (m 2 · day · kPa).

[0026] Furthermore, the barrier layer comprises the following raw materials in parts by weight: 100 parts of barrier layer biodegradable polyester, 1-10 parts of auxiliary agent A, 0.1-10 parts of auxiliary agent B, and 1-30 parts of auxiliary agent C; wherein, auxiliary agent A is preferably 2-8 parts, more preferably 4-7 parts; auxiliary agent B is preferably 0.3-8 parts, more preferably 0.5-5 parts; auxiliary agent C is preferably 3-20 parts, more preferably 5-15 parts; and / or

[0027] The protective layer comprises the following raw materials in parts by weight: 100 parts of biodegradable polyester for the protective layer, 1-10 parts of additive A, 0.1-5 parts of additive B, and 1-30 parts of additive C. Of these, additive A is preferably 2-8 parts, more preferably 4-7 parts; additive B is preferably 0.3-4 parts, more preferably 0.5-3 parts; and additive C is preferably 3-20 parts, more preferably 5-15 parts.

[0028] In a second aspect, a method for preparing a high-performance biodegradable film comprises the following steps:

[0029] Step 1: Blending the raw materials of the barrier layer and the raw materials of the protective layer, extruding, granulating, and drying to a moisture content of less than 400 ppm, preferably less than 200 ppm, and more preferably less than 100 ppm, respectively, to obtain a modified material for the barrier layer and a modified material for the protective layer;

[0030] Step 2: Obtain a biodegradable film through three-layer co-extrusion.

[0031] Furthermore, in step 1, a twin-screw extruder is used for extrusion, and the processing temperature of the twin-screw extruder is: the conveying section temperature is 50-300°C, preferably 90-250°C, more preferably 100-180°C; the melting section temperature is 100-300°C, preferably 120-270°C, more preferably 130-250°C; the mixing section temperature is 100-300°C, preferably 120-270°C, more preferably 130-250°C; the exhaust section temperature is 100-300°C, preferably 120-270°C, More preferably 130-250°C; homogenization section temperature 100-300°C, preferably 130-270°C, more preferably 120-220°C; extrusion die head temperature 100-300°C, preferably 130-270°C, more preferably 120-220°C; rotation speed 100-500rpm, preferably 150-350rpm, more preferably 200-300rpm; granulation adopts any one of water-cooled strand granulation, air-cooled strand granulation, underwater pelletizing, water ring pelletizing, and air-cooled hot cutting.

[0032] Furthermore, in step 2, the co-extrusion is performed by an ABC or ABA three-layer co-extruder, and the processing temperature of the barrier layer of the three-layer co-extruder is: the feeding section temperature is 50-300°C, preferably 90-250°C, more preferably 100-180°C; the melting section temperature is 100-300°C, preferably 120-270°C, more preferably 130-250°C; the homogenization section temperature is 100-300°C, preferably 120-270°C, more preferably 130-250°C;

[0033] The processing temperature of the protective layer of the three-layer co-extruder is: the feeding section temperature is 50-300°C, preferably 90-250°C, more preferably 100-180°C; the melting section temperature is 100-300°C, preferably 120-270°C, more preferably 130-250°C; the homogenizing section temperature is 100-300°C, preferably 120-270°C, more preferably 130-250°C; the mold temperature is 100-300°C, preferably 130-270°C, more preferably 120-220°C.

[0034] A third aspect provides an application of a high-performance biodegradable film, wherein the high-performance biodegradable film is used in electronics, agriculture, food, medical treatment or environmental protection. DETAILED DESCRIPTION

[0035] The principles and features of the present invention are described below. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention. Where specific techniques or conditions are not specified in the examples, the techniques or conditions described in the literature in this field or the product instructions are used. Where the manufacturers of the reagents or instruments used are not specified, they are all conventional products that can be purchased through regular channels.

[0036] Example 1

[0037] This embodiment relates to a method for preparing a high-performance biodegradable film, comprising the following specific steps:

[0038] 1) Raw material pretreatment: All raw materials are vacuum dried until the moisture content is less than 400ppm;

[0039] 2) Preparation of modified materials for barrier layer

[0040] Various raw materials were weighed according to weight proportion and mixed evenly, and melt-extruded through a twin-screw extruder. The twin screws were co-rotating parallel twin screws with a length-to-diameter ratio of 36:1. The temperatures were 100° C. in the conveying section, 240° C. in the melting section, 240° C. in the mixing section, 240° C. in the exhaust section, 220° C. in the homogenizing section, 210° C. in the extrusion die, and 250 rpm in the screw speed. The barrier layer blend was obtained by air-cooling and granulation, and then dried at 80° C. until the moisture content was less than 100 ppm to obtain a modified material for the barrier layer. The modified material was sealed in an aluminum foil bag and stored for later use.

[0041] 3) Preparation of modified material for protective layer

[0042] Various raw materials were weighed according to weight proportion and mixed evenly, and melt-extruded through a twin-screw extruder. The twin screws were co-rotating parallel twin screws with an aspect ratio of 36:1. The temperatures were 80° C. in the conveying section, 220° C. in the melting section, 220° C. in the mixing section, 220° C. in the exhaust section, 200° C. in the homogenizing section, 190° C. in the extrusion die, and 250 rpm in the screw speed. The barrier layer blend was obtained by air-cooling and granulation, and then dried at 70° C. until the moisture content was less than 100 ppm to obtain a modified material for the protective layer. The modified material was sealed in an aluminum foil bag and stored for later use.

[0043] Table 1 Raw materials and amounts of barrier layer and protective layer in Example 1

[0044]

[0045] 4) Preparation of three-layer composite biodegradable film

[0046] The barrier layer modified material and the protective layer modified material were added to the inner and outer screw feed ports of an ABC three-layer co-extruder, respectively. The aspect ratio of all three screws was 30:1. The screw temperatures for the barrier layer were 100°C in the feeding section, 240°C in the melting section, and 240°C in the homogenizing section. The screw temperatures for the protective layer were 80°C in the feeding section, 220°C in the melting section, and 220°C in the homogenizing section. A film blowing process was used, with the die temperatures increasing from bottom to top to 230°C, 220°C, and 200°C. After the three-layer composite melt was extruded from the die, films of varying thicknesses were produced through a series of blown and drawn processes. The films were then wound using a center take-up system. The total thickness of the films was 150 μm, with the barrier layer having a thickness of 30 μm and the protective layer having a thickness of 120 μm.

[0047] Example 2

[0048] Compared with Example 1, the total thickness of the film is 150 μm, the thickness of the barrier layer is 50 μm, and the thickness of the protective layer is 100 μm.

[0049] Example 3

[0050] Compared with Example 1, the total thickness of the film is 150 μm, the thickness of the barrier layer is 100 μm, and the thickness of the protective layer is 50 μm.

[0051] Example 4

[0052] This embodiment relates to a method for preparing a high-performance biodegradable film, comprising the following specific steps:

[0053] 1) Raw material pretreatment: All raw materials are vacuum dried until the moisture content is less than 400 ppm.

[0054] 2) Preparation of modified materials for barrier layer

[0055] Various raw materials were weighed according to weight proportion and mixed evenly, and melt-extruded through a twin-screw extruder. The twin screws were co-rotating parallel twin screws with an aspect ratio of 36:1. The temperatures were 70°C for the conveying section, 140°C for the melting section, 140°C for the mixing section, 140°C for the exhaust section, 130°C for the homogenizing section, 120°C for the extrusion die, 200 rpm for screw speed, and air-cooled strand granulation to obtain a barrier layer blend. The mixture was then dried at 70°C until the moisture content was less than 100 ppm to obtain a modified material for the barrier layer. The material was then sealed in an aluminum foil bag for storage.

[0056] 3) Preparation of modified material for protective layer

[0057] Various raw materials were weighed according to weight proportion and mixed evenly, and melt-extruded through a twin-screw extruder. The twin screws were co-rotating parallel twin screws with an aspect ratio of 36:1. The temperatures were 80° C. in the conveying section, 170° C. in the melting section, 170° C. in the mixing section, 170° C. in the exhaust section, 160° C. in the homogenizing section, 150° C. in the extrusion die, 250 rpm in the screw speed, and air-cooled strand granulation was performed to obtain a barrier layer blend, which was then dried at 70° C. until the moisture content was less than 100 ppm to obtain a modified material for the protective layer. The modified material was sealed in an aluminum foil bag and stored for later use.

[0058] Table 2 Raw materials and amounts of barrier layer and protective layer in Example 4

[0059]

[0060]

[0061] 4) Preparation of three-layer composite biodegradable film

[0062] The barrier layer modified material and the protective layer modified material were added to the inner and outer screw feed ports of an ABC three-layer co-extruder, respectively. The aspect ratio of all three screws was 30:1. The screw temperatures for the barrier layer were 7°C in the feeding section, 140°C in the melting section, and 140°C in the homogenizing section. The screw temperatures for the protective layer were 80°C in the feeding section, 170°C in the melting section, and 170°C in the homogenizing section. A casting process was used, and the casting die temperature was 150°C. After the three-layer composite melt was extruded from the die, the cooling and setting rollers were cooled to 10-20°C. Films of varying thicknesses were then produced by pulling and wound up using a surface winding method. The total thickness of the film was 150μm, with the barrier layer having a thickness of 50μm and the protective layer having a thickness of 100μm.

[0063] Example 5

[0064] Compared with Example 4, the total thickness of the film is 250 μm, the thickness of the barrier layer is 50 μm, and the thickness of the protective layer is 200 μm.

[0065] Example 6

[0066] Compared with Example 4, the total thickness of the film is 350 μm, the thickness of the barrier layer is 50 μm, and the thickness of the protective layer is 300 μm.

[0067] Comparative Example 1: Single protective layer

[0068] The protective layer modified material in Example 1 was processed by a single-layer extrusion film blowing machine. The aspect ratio of the screw was 30:1, the temperature was 80°C in the feeding section, 220°C in the melting section, and 220°C in the homogenizing section. The film blowing mold temperature was 220°C, 210°C, and 205°C from bottom to top. After the melt was extruded from the die, it was blown and pulled to prepare a film, and then wound by surface winding.

[0069] Comparative Example 2: Single barrier layer

[0070] The barrier layer modified material in Example 1 was processed by a single-layer extrusion film blowing machine. The aspect ratio of the screw was 30:1, the temperature was 100°C in the feeding section, 240°C in the melting section, and 240°C in the homogenizing section. The temperatures of the film blowing mold were 240°C, 230°C, and 220°C from bottom to top. After the melt was extruded from the die, it was blown and pulled to prepare a film, which was then wound up by surface winding.

[0071] Comparative Example 3: Three-layer composite protective layer

[0072] The protective layer modified material in Example 1 was added to the inner screw feed port and the outer screw feed port of the ABC three-layer co-extruder. The aspect ratio of the screw was 30:1. The processing temperature of the three extruders was 80°C in the feeding section, 220°C in the melting section, and 220°C in the homogenizing section. The temperature of the film blowing mold was 220°C, 210°C, and 205°C from bottom to top. After the melt was extruded from the die, it was blown and pulled to prepare a film, and then wound by surface winding.

[0073] Comparative Example 4: Three-layer barrier layer composite

[0074] The barrier layer modified material in Example 1 was added to the inner screw feed port and the outer screw feed port of an ABC three-layer co-extruder. The aspect ratio of the screw was 30:1. The processing temperatures of the three extruders were 100°C in the feeding section, 240°C in the melting section, and 240°C in the homogenizing section. The temperatures of the film blowing mold were 240°C, 230°C, and 220°C from bottom to top. After the melt was extruded from the die, it was blown and pulled to prepare a film, which was then wound up by surface winding.

[0075] Comparative Example 5: Composite barrier layer and protective layer

[0076] The barrier layer modified material and the protective layer modified material in Example 1 were respectively added to the inner layer screw feed port and the outer layer screw feed port of an AB type two-layer co-extruder. The aspect ratio of the two screws was 30:1. The screw temperature of the barrier layer was 100°C in the feeding section, 240°C in the melting section, and 240°C in the homogenizing section. The screw temperature of the protective layer was 80°C in the feeding section, 220°C in the melting section, and 220°C in the homogenizing section. A film blowing process was adopted, and the film blowing mold temperatures were 230°C, 220°C, and 200°C from bottom to top. After the three-layer composite melt was extruded from the die, the film was prepared by blowing and pulling in sequence, and then wound up by surface winding.

[0077] Test example

[0078] (1) Tensile strength and elongation at break were tested according to GB / T 1040.2-2006 at a tensile speed of 50 mm / min.

[0079] (2) Peel strength was tested according to GB / T 2791-1995 at a tensile speed of 100 mm / min;

[0080] (3) Oxygen permeability coefficient was tested according to ASTM F3985 under the conditions of 38° C., 0% RH, and 100% O 2 .

[0081] (4) Water vapor transmission coefficient was tested according to ASTM F1249 at 38°C and 90% RH.

[0082] Table 3 Experimental results

[0083]

[0084]

[0085] As can be seen from Table 3, the film of Comparative Example 1 with a single protective layer has low strength and poor barrier properties. The film of Comparative Example 2 with a single barrier layer has good strength and barrier properties, but poor film processability and low elongation at break. The composite film of Comparative Example 3 with three protective layers has improved barrier properties compared to Comparative Example 1, but the improvement is insufficient and the barrier properties are still very poor. Comparative Example 4 has high strength and good barrier properties, but the elongation at break is lower than that of Comparative Example 1, and the toughness is too poor. Compared with Example 1, the various properties of Comparative Example 5 are slightly lower. However, the exposed barrier layer is easily degraded, which affects the strength, barrier properties, and other properties. In Example 1, the total thickness of the three groups A, B, C, and C is unchanged. As the thickness of the barrier layer increases, the barrier effect is significantly improved. Compared with the three groups A, B, and C in Example 2, when the barrier layer thickness is the same, the barrier properties are slightly improved as the thickness of the protective layer increases, but the improvement is not significant. Therefore, the barrier properties are mainly determined by the formula combination and thickness of the barrier layer. In addition, the peel strength in the examples is greater than 2.5N / 15mm, and the tensile strength is greater than 30MPa, which proves that the film prepared by the method of the present invention has the characteristics of biodegradability, high strength, strong adhesion, and excellent barrier performance.

[0086] In summary, the present invention has the following advantages: (1) No adhesive layer: the adhesive force between the layers is increased by adding an adhesive to the formulation system; (2) High strength: tensile strength of 20-100 MPa; (3) High barrier: the water vapor permeability coefficient can reach 1g·mil / (m 2 ·day·kPa), the oxygen permeability coefficient can reach 0.25cc·mil / (m 2 ·day·atm); (4) Biodegradation: Under industrial composting conditions, it can be completely degraded in 3-6 months; (5) Easy to process: It can be processed by three-layer co-extrusion or three-layer co-blowing equipment.

[0087] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0088] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A high-performance biodegradable film, characterized in that: The biodegradable film includes a barrier layer and protective layers located on both sides of the barrier layer. The raw materials of the barrier layer include, by weight, 85 parts of polyglycolic acid, 15 parts of polybutylene terephthalate adipate, 5 parts of ethylene-ethyl acrylate copolymer, 0.3 parts of ADR 4468, 3 parts of epoxidized soybean oil, 0.15 parts of Irganox 1010, 0.15 parts of Irganox 168, 0.2 parts of UV-531, and 2 parts of talc. The raw materials of the protective layer include, by weight, 20 parts of polyglycolic acid, 80 parts of polybutylene terephthalate adipate, 5 parts of ethylene-ethyl acrylate copolymer, 0.3 parts of ADR 4468, 3 parts of epoxidized soybean oil, 0.15 parts of Irganox 1010, 0.15 parts of Irganox 168, 0.2 parts of UV-531, and 5 parts of talc. The method for preparing a high-performance biodegradable film comprises the following steps: 1) Raw material pretreatment: All raw materials are vacuum dried until the moisture content is less than 400ppm; 2) Modified materials for preparing barrier layer: Various raw materials were weighed and mixed uniformly according to weight ratio, and melt-extruded through a twin-screw extruder. The twin screws were co-rotating parallel twin screws with an aspect ratio of 36:

1. The temperatures were 100° C. in the conveying section, 240° C. in the melting section, 240° C. in the mixing section, 240° C. in the exhaust section, 220° C. in the homogenizing section, 210° C. in the extrusion die, and 250 rpm in the screw speed. The barrier layer blend was obtained by air-cooling and granulation, and then dried at 80° C. until the moisture content was less than 100 ppm to obtain a modified material for the barrier layer. The modified material was sealed in an aluminum foil bag and stored for later use. 3) Modified material for preparing protective layer: Various raw materials were weighed and mixed uniformly according to weight ratio, and melt-extruded through a twin-screw extruder. The twin screws were co-rotating parallel twin screws with an aspect ratio of 36:

1. The temperatures were 80° C. in the conveying section, 220° C. in the melting section, 220° C. in the mixing section, 220° C. in the exhaust section, 200° C. in the homogenizing section, 190° C. in the extrusion die, and 250 rpm in the screw speed. The barrier layer blend was obtained by air-cooling and granulation, and then dried at 70° C. until the moisture content was less than 100 ppm to obtain a modified material for the protective layer. The modified material was sealed in an aluminum foil bag and stored for later use. 4) Preparation of three-layer composite biodegradable film: The barrier layer modified material and the protective layer modified material were respectively added to the inner screw feed port and the outer screw feed port of an ABC three-layer co-extruder. The aspect ratio of the three screws was 30:

1. The screw temperatures of the barrier layer were 100°C in the feeding section, 240°C in the melting section, and 240°C in the homogenizing section. The screw temperatures of the protective layer were 80°C in the feeding section, 220°C in the melting section, and 220°C in the homogenizing section. A film blowing process was adopted, and the film blowing mold temperatures were 230°C, 220°C, and 200°C from bottom to top. After the three-layer composite melt was extruded from the die, films of different thicknesses were prepared by blowing and pulling in sequence, and were wound in a center winding manner. The total thickness of the film was 150 μm, the thickness of the barrier layer was 30 μm, 50 μm, or 100 μm, and the thickness of the protective layer was 120 μm, 100 μm, or 50 μm. The tensile strength of the biodegradable film is greater than 48 MPa; the interlayer peel strength between the barrier layer and the protective layer is 2.8 N / 15 mm to 3.1 N / 15 mm; the oxygen permeability coefficient of the biodegradable film is 0.25 cc·mil / (m 2 ·day·atm) to 1.75cc·mil / (m 2 ·day·atm); the water vapor permeability coefficient of the biodegradable film is 0.9g·mil / (m 2 ·day·kPa) to 3.2g·mil / (m 2 ·day·kPa).

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