Multilayer barrier saline-alkaline tolerant biodegradable mulching film and preparation method thereof

Abstract

A functional master batch A and a functional master batch B are firstly subjected to blow molding in a three-layer co-extrusion film blowing mode to form a BAB three-layer structure film material, then low-molecular wax in the layer B is migrated to the surface of the film material in an infrared thermal migration mode, a wax protection layer C is formed, and the wax protection layer C is formed. And finally, the multi-layer barrier saline-alkaline tolerant biodegradable mulching film with a CBABC five-layer structure is formed. According to the mulching film provided by the invention, on one hand, the water vapor barrier property of the biodegradable mulching film is improved, and on the other hand, the damage of metal ions and hydroxyl ions to a resin molecular chain structure is isolated, so that the laying of the biodegradable mulching film in a high-saline-alkali soil environment is not influenced; and the resin layer not only preserves excellent mechanical properties, but also protects the anti-aging functional additive, so that the anti-aging time of the biodegradable mulching film is greatly prolonged.

Description

Technical Field

[0001] The invention relates to the field of degradable materials, and in particular to a multi-layer barrier salt-alkali resistant biodegradable mulch film and a preparation method thereof. Background Art

[0002] Biodegradable mulch is gradually becoming known to everyone. Through the promotion and application of biodegradable mulch in recent years, biodegradable mulch has become one of the most effective ways to control farmland pollution. Due to the molecular structure of its main raw materials PBAT and PLA, biodegradable mulch has excellent biodegradability, but it is also easily affected by substances in the environment, which accelerates degradation and makes the degradation cycle uncontrollable. Among them, the biggest influence on biodegradable mulch is salt, alkali, metal ions and hydroxide ions will catalyze the accelerated degradation of resin after contacting PBAT and PLA molecular segments.

[0003] The salt components of saline-alkali land of different degrees include NaCl, MgCL2, KCl, CaCl2, MgSO4, etc., and the main alkali components are Na2CO3 and NaHCO3. During the growth of crops, fertilizers and pesticides are applied, and a large amount of fertilizers and pesticides will also bring a large amount of salt and alkali substances to the soil or on the surface of the mulch. The saline and alkali substances in the soil will damage the biodegradable mulch laid locally, causing the degradable mulch to degrade prematurely and unable to meet the growth needs of crops.

[0004] Patent CN118181919A "A salt-alkali resistant and degradable ground film and its preparation method" adopts three-layer co-extrusion and adds PBAT, PPC, PGA, PBST and other resins and corrosion-resistant additives and anti-hydrolysis additives, but they cannot effectively isolate the salt-alkali ions from contacting and damaging the resin, and the added PGA resin will accelerate biodegradation while providing barrier properties. Summary of the invention

[0005] 1. Technical issues to be resolved

[0006] Due to the molecular structure of its main raw material PBAT, biodegradable mulch has excellent biodegradability, but it is also easily affected by substances in the environment, thereby accelerating degradation, resulting in an uncontrollable degradation cycle. Among them, the greatest impact on biodegradable mulch is salt and alkali. Metal ions and hydroxide ions will catalyze the accelerated degradation of PBAT molecular segments when they come into contact with PBAT molecular segments.

[0007] Conventional biodegradable mulch cannot isolate metal ions and hydroxide ions from damaging the resin molecular chain structure, resulting in accelerated degradation of the biodegradable mulch. If excessive low-molecular wax and inorganic minerals are introduced into the conventional biodegradable mulch formula system, only temporary barrier properties can be provided. The introduction of a large amount of small-molecule wax and inorganic minerals will destroy the balance of the biodegradable mulch system, resulting in a significant reduction in the mechanical properties of the biodegradable mulch. At the same time, the low-molecular wax will also migrate out small-molecule functional additives while migrating, resulting in poor aging resistance.

[0008] (II) Technical solution

[0009] In order to solve the above technical problems, the present invention provides a multi-layer barrier salt-alkali resistant biodegradable mulch film, which has a 5-layer structure of CBABC stacked in sequence, wherein layer A is a functional resin layer, layer B is a high barrier mineral powder protective layer, and layer C is a wax protective layer;

[0010] The thickness of layer A is 4-10 μm, the thickness of layer B is 1-5 μm, and the thickness of layer C is 0.1-1 μm.

[0011] The A layer is formed by blown film of functional masterbatch A, and the ingredients of functional masterbatch A include PBAT, PLA, PPC, PBS, PBST, PBSA, chain extender, anti-hydrolysis agent, silica, titanium dioxide, UV stabilizer, UV absorber, lubricant and antioxidant.

[0012] The B layer is made of functional masterbatch B by blown film. The ingredients of functional masterbatch B include PBAT, barrier inorganic mineral powder, wax powder, antioxidant, coupling agent, and biodegradable carbon black masterbatch.

[0013] The C layer is formed by migrating the low molecular weight wax in the B layer to the surface of the film material by infrared thermal migration, and its ingredients include paraffin powder with a melting point below 100°C and low melting point polyethylene wax.

[0014] Functional masterbatch A includes the following raw materials in parts by weight: 40-95 parts of PBAT, 3-30 parts of PLA, 2.5-30 parts of PPC, 0.01-30 parts of PBS, 0.01-30 parts of PBST, 0.01-30 parts of PBSA, 0.01-2 parts of chain extender, 0.01-2 parts of anti-hydrolysis agent, 0.01-5 parts of silicon dioxide, 0.01-5 parts of titanium dioxide, 0.01-5 parts of ultraviolet stabilizer, 0.01-5 parts of ultraviolet absorber, 0.01-5 parts of lubricant, and 0.01-5 parts of antioxidant;

[0015] The chain extender is selected from one or more of ADR4468, KL4370, KL4370B, KL40, CE301, and XY-4370;

[0016] The anti-hydrolysis agent is selected from one or more of C-768, HMV-5CA-LC, HMV-15CA, H-210, SW100, SW-500, bio362, and SDA3600;

[0017] The ultraviolet light stabilizer is selected from one or more of UV-801, UV-944, UV-622, and UV-770;

[0018] The ultraviolet light absorber is selected from one or more of UV-1, UV-P, UV-326, UV-327, UV-328, UV-329, UV-320, UV-360, UV-531, UV-538, UV-571, UV-1157, UV-1164, UV-234, UV-312, UV-928, and UV-3030;

[0019] The lubricant is selected from one or more of PETS, EBS, PE wax, monoglyceride, erucamide, and oleamide;

[0020] The antioxidant is selected from one or more of antioxidant 1010, antioxidant 168, antioxidant 626, antioxidant 618, antioxidant 9228, antioxidant B225, and antioxidant B215;

[0021] Functional masterbatch A is prepared by uniformly mixing the raw material additives using a high-speed mixer and then processing using a twin-screw extruder.

[0022] Functional masterbatch B includes the following raw materials in parts by weight: 20-95 parts of PBAT, 1-80 parts of barrier inorganic mineral powder, 0.01-30 parts of wax powder, 0.01-5 parts of antioxidant, 0.01-5 parts of coupling agent, 0.01-15 parts of biodegradable carbon black masterbatch,

[0023] The barrier inorganic mineral powder is selected from one or more of talc powder, mica powder, modified montmorillonite DK2, modified montmorillonite DK4, and modified montmorillonite DK-32B;

[0024] The wax powder is selected from at least one of paraffin powder and polyethylene wax having a melting point below 100°C;

[0025] The antioxidant is selected from one or more of antioxidant 1010, antioxidant 1076, antioxidant 1024, antioxidant 1098, antioxidant 245, antioxidant 1135, antioxidant 2246, antioxidant 3114, antioxidant 330, antioxidant 1035, antioxidant 1520, antioxidant 168, antioxidant 626, antioxidant 618, antioxidant 9228, antioxidant B225, and antioxidant B215;

[0026] The coupling agent is selected from one or more of silane coupling agent KH-550, silane coupling agent KH-560, silane coupling agent KH-570, silane coupling agent KH-151, silane coupling agent JS-8112, silane coupling agent A-171 aluminate coupling agent, and DL411;

[0027] Functional masterbatch B is prepared by uniformly mixing the raw materials with a high-speed mixer and then processing them with a twin-screw extruder.

[0028] A method for processing a multi-layer barrier salt-alkali-resistant biodegradable ground film.

[0029] S1. The functional masterbatch A and the functional masterbatch B are put into a BAB three-layer co-extrusion film blowing machine to form a film to obtain a film having a BAB three-layer structure; wherein A is the core layer and B is the surface layer;

[0030] The blow ratio of blow molding is 3, among which the processing temperatures of layer A are 145±10℃ for zone 1, 155±10℃ for zone 2, 165±10℃ for zone 3, 170±10℃ for zone 4, and 175±10℃ for zone 5; the processing temperatures of layer B are 125±10℃ for zone 1, 135±10℃ for zone 2, and 140±10℃ for zones 3, 4, and 5;

[0031] The corner temperature is 160±10℃, the die section 1 temperature is 160±10℃, the die section 2 temperature is 155±10℃, and the main machine feed ratio is 0-5;

[0032] S2. The film material with the three-layer structure of BAB prepared in S1 is drawn into the drawing section, an infrared heating device (1) and a blowing cooling device (2) are installed in the drawing section, and the infrared heating and blowing cooling are turned on to make the low molecular wax in the B layer thermally migrate to the outer layer to form the C layer, thereby forming a high-barrier salt-alkali resistant biodegradable ground film with a 5-layer structure of CBABC stacked in sequence.

[0033] Preferably, the heating temperature of the infrared heating is 85-95°C.

[0034] Preferably, the thickness of the blown film with air cooling is 7-20 μm.

[0035] The present invention also provides a multi-layer barrier salt-alkali resistant biodegradable mulch film for use in farmland.

[0036] (III) Beneficial effects

[0037] The above technical solution of the present invention has the following advantages:

[0038] 1. The present invention protects the biodegradable functional resin layer in the middle through a multi-layer composite structure, and can isolate the biodegradable resin from salt and alkali for a certain period of time. The wax film protective layer provides the first isolation protection, the high barrier mineral layer provides the second isolation protection, and the core resin layer provides excellent mechanical properties and aging resistance. In this way, on the one hand, the water vapor barrier of the biodegradable mulch is improved, and on the other hand, the damage to the resin molecular chain structure by metal ions and hydroxide ions is isolated, so that the laying of the biodegradable mulch in a high-salt and alkali soil environment is not affected, and the resin layer not only preserves the excellent mechanical properties, but also protects the aging-resistant functional additives, thereby greatly improving the aging resistance time of the biodegradable mulch.

[0039] 2. During the processing of B masterbatch, high-content lamellar crystal structure inorganic powder is selected to provide high barrier for B layer membrane material. At the same time, adding it together with wax powder during the processing can increase the shear force and friction force during the equipment processing. On the one hand, it makes the powder more evenly dispersed, and on the other hand, it prevents the material from slipping in the screw and improves the material processing stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 The schematic diagram is a structural diagram of a high barrier, salt-alkali resistant CBABC 5-layer biodegradable mulch film;

[0041] Figure 2 This is the distribution diagram of infrared heating and air blowing cooling in the extraction section of the present invention;

[0042] Figure 3 Schematic diagram of the structural changes of high barrier salt-alkali resistant biodegradable mulch film.

[0043] In the figure: 1. Infrared heating device; 2. Blowing cooling device; A. Functional resin layer, B. High barrier mineral powder protective layer, C. Wax protective layer. DETAILED DESCRIPTION

[0044] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0045] A multi-layer barrier salt-alkali resistant biodegradable mulch film, such as Figure 1 As shown, Figure 1 It is a schematic diagram of the structure of a high-barrier, salt-alkali-resistant CBABC5-layer biodegradable mulch film;

[0046] A multi-layer barrier salt-alkali resistant biodegradable mulch film, having a 5-layer structure of CBABC stacked in sequence, wherein layer A is a functional resin layer, layer B is a high barrier mineral powder protective layer, and layer C is a wax protective layer;

[0047] The thickness of layer A is 4-10 μm, the thickness of layer B is 1-5 μm, and the thickness of layer C is 0.1-1 μm.

[0048] The A layer is formed by blown film of functional masterbatch A, and the ingredients of functional masterbatch A include PBAT, PLA, PPC, PBS, PBST, PBSA, chain extender, anti-hydrolysis agent, silica, titanium dioxide, UV stabilizer, UV absorber, lubricant and antioxidant.

[0049] The B layer is made of functional masterbatch B by blown film. The ingredients of functional masterbatch B include PBAT, barrier inorganic mineral powder, wax powder, antioxidant, coupling agent, and biodegradable carbon black masterbatch.

[0050] The C layer is formed by migrating the low molecular weight wax in the B layer to the surface of the film material by infrared thermal migration, and its ingredients include paraffin powder with a melting point below 100°C and low melting point polyethylene wax.

[0051] Composition of functional masterbatch A and its processing method.

[0052] Raw materials and addition amounts in functional masterbatch A: PBAT 40-95 parts, PLA 4-30 parts, PPC 2.5-30 parts, PBS 0.01-30 parts, PBST 0.01-30 parts, PBSA 0.01-30 parts, chain extender 0.01-2 parts, anti-hydrolysis agent 0.01-2 parts, silica 0.01-5 parts, titanium dioxide 0.01-5 parts, UV stabilizer 0-.015 parts, UV absorber 0.01-5 parts, lubricant 0.01-5 parts, antioxidant 0.01-5 parts.

[0053] The important role of PBAT, PLA, PPC, PBS, PBST and PBSA resins in the functional masterbatch A raw material is to provide the mechanical properties of the A layer film and the barrier properties of some materials.

[0054] The chain extenders in the functional masterbatch A raw material include: ADR4468, KL4370, KL4370B, KL40, CE301, XY-4370. One or more of them are added in combination to improve the compatibility of PBAT and PLA, reduce the terminal carboxyl group of PBAT resin, and improve the hydrolysis resistance.

[0055] The anti-hydrolysis agents in the raw materials of functional masterbatch A include: C-768, HMV-5CA-LC, HMV-15CA, H-210, SW100, SW-500, bio362, SDA3600, one or more of which are added in combination to improve the hydrolysis resistance.

[0056] The silicon dioxide in the functional masterbatch A raw material is mainly used as a nucleating agent to increase the cooling rate during processing.

[0057] The titanium dioxide in the raw material of functional composite masterbatch A mainly functions to absorb and shield ultraviolet rays for the A-layer film material, thereby improving the ultraviolet aging performance.

[0058] The UV stabilizers in the functional masterbatch A raw material include: one or more of UV-801, UV-944, UV-622, and UV-770 are added in combination to improve the light stability of the A layer film material.

[0059] The ultraviolet light absorbers in the functional masterbatch A raw material include: one or more of UV-1, UV-P, UV-326, UV-327, UV-328, UV-329, UV-320, UV-360, UV-531, UV-538, UV-571, UV-1157, UV-1164, UV-234, UV-312, UV-928, and UV-3030, which are added in combination to absorb ultraviolet light and improve the ultraviolet aging resistance of the A layer film.

[0060] The lubricants in the raw materials of functional masterbatch A include: one or more of PETS, EBS, PE wax, monoglyceride, erucamide, and oleamide, which are added in combination to play a processing lubrication role.

[0061] The antioxidants in the raw materials of functional masterbatch A include: one or more of antioxidant 1010, antioxidant 168, antioxidant 626, antioxidant 618, antioxidant 9228, antioxidant B225, and antioxidant B215.

[0062] Functional masterbatch A, all raw materials and additives are mixed evenly using a high-speed mixer and then processed into A masterbatch using a twin-screw extruder.

[0063] The composition of functional masterbatch B and its processing method;

[0064] Raw materials and addition amounts in functional masterbatch B: PBAT 20-95 parts, barrier inorganic mineral powder 1-80 parts, wax powder 0.01-30 parts, antioxidant 0.01-5 parts, coupling agent 0.01-5 parts, biodegradable carbon black masterbatch 0.01-15 parts.

[0065] The PBAT in the functional masterbatch B raw material mainly acts as a carrier, processing the barrier inorganic mineral powder and wax powder into blow-molded functional materials.

[0066] The barrier inorganic mineral powder in the raw material of functional masterbatch B includes one or more of talcum powder, mica powder, modified montmorillonite DK2, modified montmorillonite DK4 and modified montmorillonite DK-32B. Its lamellar crystal structure provides high barrier properties for the B layer membrane material. At the same time, adding it together with wax powder during the processing can increase the shear force and friction force during the equipment processing. On the one hand, it makes the masterbatch more evenly dispersed, and on the other hand, it prevents the material from slipping in the screw and not feeding.

[0067] The wax powder in the raw material of functional masterbatch B includes one or more composite additions of paraffin powder, polyethylene wax, oxidized polyethylene wax, and cracked polyethylene wax. The melting point is required to be lower than 100°C. The main function is to form a wax film protective layer C after thermal precipitation.

[0068] The antioxidants in the functional masterbatch B raw material include: antioxidant 1010, antioxidant 1076, antioxidant 1024, antioxidant 1098, antioxidant 245, antioxidant 1135, antioxidant 2246, antioxidant 3114, antioxidant 330, antioxidant 1035, antioxidant 1520, antioxidant 168, antioxidant 626, antioxidant 618, antioxidant 9228, antioxidant B225, antioxidant B215 or one or more of the above.

[0069] The coupling agents in the functional masterbatch B raw material include: one or more of silane coupling agent KH-550, silane coupling agent KH-560, silane coupling agent KH-570, silane coupling agent KH-151, silane coupling agent JS-8112, silane coupling agent A-171 aluminate coupling agent, and DL411.

[0070] Functional masterbatch B, all raw materials and additives are mixed evenly using a high-speed mixer and then processed into B masterbatch using a twin-screw extruder.

[0071] Processing method of multi-layer barrier salt-alkali resistant biodegradable mulch film:

[0072] 1. Put the functional masterbatch A and B into a BAB three-layer co-extrusion film blowing machine for film blowing, with a blow-up ratio of 3. A is the core layer, B is the surface layer, and the film blowing process is shown in Table 1.

[0073] Table 1

[0074]

[0075] 2. Install infrared heating device and air cooling device in the drawing section, such as Figure 2 , Figure 2 This is the distribution diagram of infrared heating and air cooling in the extraction section of the present invention; turn on infrared heating and air cooling, the heating temperature is 90±5℃, so that the low molecular wax in layer B is thermally migrated to the outer layer C, such as Figure 3 , Figure 3 This is a schematic diagram of the structural changes of high barrier salt-alkali resistant biodegradable mulch film, which is then rolled into a film roll. The blown film thickness is required to be between 7-20μm.

[0076] Example 1

[0077] This embodiment introduces a method for preparing a multi-layer barrier salt-alkali resistant biodegradable mulch film as embodiment 1.

[0078] A multi-layer barrier salt-alkali resistant biodegradable ground film, the structure of which is as follows Figure 1 As shown, layer A is a functional resin layer, layer B is a high barrier mineral powder protective layer, and layer C is a wax protective layer. The thickness of layer A is 7 μm, the thickness of layer B is 2.2 μm, and the thickness of layer C is 0.3 μm.

[0079] The preparation method of the multi-layer barrier salt-alkali resistant biodegradable mulch film is as follows:

[0080] 1. The ingredient list of functional masterbatch A is as follows:

[0081] The raw materials and addition amounts in functional masterbatch A are: PBAT Kanghui KHB21BP11 (90 parts), PLANatureWorks4043D (5 parts), PPC Zhejiang Huafeng HF901 (2.5 parts), chain extender KL4370B (0.2), anti-hydrolysis agent HMV-5CA-LC (0.2), nano silicon dioxide (0.5), titanium dioxide (0.2), ultraviolet light stabilizer UV-622 (0.3), ultraviolet light absorber UV-1157 (0.2), ultraviolet light absorber UV-326 (0.3), PETS (0.2), antioxidant 1024 (0.2), antioxidant 626 (0.2).

[0082] 2. The ingredient list of functional masterbatch B is as follows:

[0083] The raw materials and addition amounts in functional masterbatch B are: PBAT Kanghui KHB21BP11 (43.5 parts), barrier inorganic mineral powder modified montmorillonite DK4 (50 parts), low melting point polyethylene wax (5 parts), antioxidant 1010 (0.3 parts), antioxidant 168 (0.2 parts), and silane coupling agent KH-570 (1 part).

[0084] 3. Functional masterbatch A is prepared by mixing the raw materials uniformly with a high-speed mixer and then processing them with a twin-screw extruder.

[0085] Functional masterbatch B is prepared by uniformly mixing the raw materials with a high-speed mixer and then processing them with a twin-screw extruder.

[0086] 4. Put the functional masterbatch A and B into a BAB three-layer co-extrusion film blowing machine for film blowing, with a blowing ratio of 3. A is the core layer, B is the surface layer, and the film blowing process is shown in Table 2.

[0087] Table 2

[0088]

[0089] 5. Turn on the infrared heating device and air cooling in the drawing section, the heating temperature is 95°C, so that the low molecular wax in layer B can be thermally migrated to the outer layer C. The thickness of the blown film after air cooling is 12μm, and then it is rolled into a film roll to obtain a multi-layer barrier salt-alkali resistant biodegradable mulch film.

[0090] Example 2

[0091] This example introduces a method for preparing a multi-layer barrier salt-alkali resistant biodegradable mulch film as Example 2.

[0092] A multi-layer barrier salt-alkali resistant biodegradable ground film, the structure of which is as follows Figure 1 As shown, layer A is a functional resin layer, layer B is a high barrier mineral powder protective layer, and layer C is a wax protective layer. The thickness of layer A is 7 μm, the thickness of layer B is 2.2 μm, and the thickness of layer C is 0.3 μm.

[0093] The preparation method of the multi-layer barrier salt-alkali resistant biodegradable mulch film is as follows:

[0094] 1. The ingredient list of functional masterbatch A is as follows:

[0095] PBAT Kanghui KHB21BP11 (95 parts), PLA NatureWorks4043D (3 parts), chain extender ADR4468 (0.2), nano-silicon dioxide (0.5), titanium dioxide (0.2), UV stabilizer UV-770 (0.2), UV stabilizer UV-944 (0.2), UV absorber UV-328 (0.2), UV absorber UV-531 (0.2), erucic acid amide (0.2), antioxidant B225 (0.3).

[0096] 2. The ingredient list of functional masterbatch B is as follows:

[0097] PBAT Kanghui KHB21BP11 (43.5 parts), talcum powder (50 parts), paraffin powder (4 parts), B225 (0.5), and silane coupling agent KH-570 (2 parts).

[0098] 3. Functional masterbatch A is prepared by mixing the raw materials uniformly with a high-speed mixer and then processing them with a twin-screw extruder.

[0099] Functional masterbatch B is prepared by uniformly mixing the raw materials with a high-speed mixer and then processing them with a twin-screw extruder.

[0100] 4. Put the functional masterbatch A and B into a BAB three-layer co-extrusion film blowing machine for film blowing, with a blowing ratio of 3. A is the core layer, B is the surface layer, and the film blowing process is shown in Table 3.

[0101] Table 3

[0102]

[0103] 5. Turn on the infrared heating device and air cooling in the drawing section, the heating temperature is 95°C, so that the low molecular wax in layer B can be thermally migrated to the outer layer C. The thickness of the blown film after air cooling is 12μm, and then it is rolled into a film roll to obtain a multi-layer barrier salt-alkali resistant biodegradable mulch film.

[0104] Example 3

[0105] This example introduces another method for preparing a multi-layer barrier salt-alkali resistant biodegradable mulch film as Example 3.

[0106] A multi-layer barrier salt-alkali resistant biodegradable ground film, the structure of which is as follows Figure 1 As shown, layer A is a functional resin layer, layer B is a high barrier mineral powder protective layer, and layer C is a wax protective layer. The thickness of layer A is 7 μm, the thickness of layer B is 2.2 μm, and the thickness of layer C is 0.3 μm.

[0107] The preparation method of the multi-layer barrier salt-alkali resistant biodegradable mulch film is as follows:

[0108] 1. The ingredient list of functional masterbatch A is as follows:

[0109] PBAT Kanghui KHB21AP11 (92 parts), PLA NatureWorks4043D (5 parts), chain extender ADR4468 (0.2 parts), nano-silica (1 part), UV stabilizer UV-944 (0.5 parts), UV absorber UV-531 (0.5 parts), EBS (0.2 parts), antioxidant B225 (0.6 parts).

[0110] 2. The raw materials and addition amounts in functional masterbatch B are: PBAT Kanghui KHB21BP11 (60 parts), mica powder (35 parts), low melting point paraffin powder (4 parts), B225 (0.5), and silane coupling agent KH-550 (0.5 parts).

[0111] 3. Functional masterbatch A is prepared by mixing the raw materials uniformly with a high-speed mixer and then processing them with a twin-screw extruder.

[0112] Functional masterbatch B is prepared by uniformly mixing the raw materials with a high-speed mixer and then processing them with a twin-screw extruder.

[0113] 4. Put the functional masterbatch A and B into a BAB three-layer co-extrusion film blowing machine for blow molding, with a blow-up ratio of 3. A is the core layer, B is the surface layer, and the film blowing process is shown in Table 4.

[0114] Table 4

[0115]

[0116] 5. Turn on the infrared heating device and air cooling in the drawing section, the heating temperature is 95°C, so that the low molecular wax in layer B can be thermally migrated to the outer layer C. The thickness of the blown film after air cooling is 12μm, and then it is rolled into a film roll to obtain a multi-layer barrier salt-alkali resistant biodegradable mulch film.

[0117] Comparative Example 1

[0118] This comparative example introduces the use of only functional masterbatch A to process blown film as comparative example 1.

[0119] 1. The ingredient list of functional masterbatch A is as follows:

[0120] PBAT Kanghui KHB21AP11 (92 parts), PLA NatureWorks4043D (5 parts), chain extender ADR4468 (0.2 parts), nano-silica (1 part), UV stabilizer UV-944 (0.5 parts), UV absorber UV-531 (0.5 parts), EBS (0.2 parts), antioxidant B225 (0.6 parts).

[0121] 2. Functional masterbatch A processing technology: All raw materials and additives are mixed evenly using a high-speed mixer, and then processed into A masterbatch using a twin-screw extruder.

[0122] 3. Only use A masterbatch for film blowing. Put A functional masterbatch into a three-layer co-extrusion film blowing machine for film blowing. The blowing ratio is 3. The film blowing process is shown in Table 5.

[0123] Table 5

[0124]

[0125] 4. Turn on the infrared heating device and air cooling in the drawing section, the heating temperature is 95°C, the film thickness after air cooling is 12 μm, and then roll it into a film roll to obtain a degradable ground film.

[0126] Comparative Example 2

[0127] This comparative example introduces the use of only functional masterbatch B to process blown film as comparative example 2.

[0128] 1. The ingredient list of functional masterbatch B is as follows: PBAT Kanghui KHB21BP11 (60 parts), mica powder (35 parts), low melting point paraffin powder (4 parts), B225 (0.5), and silane coupling agent KH-550 (0.5 parts).

[0129] 2. Functional masterbatch B processing technology: All raw materials and additives are mixed evenly using a high-speed mixer, and then processed into B masterbatch using a twin-screw extruder.

[0130] 3. Only use B masterbatch for film blowing. Put B functional masterbatch into a three-layer co-extrusion film blowing machine for film blowing. The blowing ratio is 3. The film blowing process is shown in Table 6.

[0131] Table 6

[0132]

[0133] 4. Turn on the infrared heating device and air cooling in the drawing section, the heating temperature is 95°C, the film thickness after air cooling is 12 μm, and then roll it into a film roll to obtain a degradable ground film.

[0134] Performance Testing

[0135] Combined with the physical and chemical properties of comparative example 1, example 2, example 3, comparative example 1, and comparative example 2.

[0136] 1. According to GB / T35795-2017, the tensile load, nominal strain at break, right-angle tear load and water vapor transmission performance are tested, as shown in Table 7.

[0137]

[0138]

[0139] Table 7

[0140] It can be judged from the above data that the tensile properties, right-angle tear load performance and water vapor permeability of Example 1, Example 2, Example 3 and Comparative Example 1 all meet the national standard requirements, among which the water vapor permeability of Example 1, Example 2 and Example 3 can reach less than 140g / (㎡*24h), and the barrier performance is higher.

[0141] In Comparative Example 2, the functional masterbatch B was blown into film alone. Since there was no functional resin layer to provide high-strength mechanical performance support, the tensile properties and right-angle tear load performance data of the entire film material could not meet the use requirements.

[0142] 2. According to GB / T35795-2017, the tensile load and nominal strain at break properties after 100 hours of artificial weathering are tested, as shown in Table 8.

[0143] Table 8

[0144]

[0145]

[0146] It can be judged from the above data that the comparative example 2 does not have the mechanical properties provided by the functional resin layer and the anti-ultraviolet aging functional additive, resulting in the aging resistance performance cannot meet the use requirements. Example 1, Example 2, Example 3, and comparative example 1 can all meet the artificial climate aging IV level performance requirements in the national standard GB / T35795-2017.

[0147] 3. Saline-alkali land laying test: In the high-salinity-alkali land of Erliugong Town, Changji City, Xinjiang Uygur Autonomous Region, cotton crop laying experiments were carried out, and observations and comparisons were made at different time periods, as shown in Table 9.

[0148] Table 9

[0149]

[0150] It can be judged from the above data that the aging resistance of Example 1, Example 2 and Example 3 in high saline-alkali areas far exceeds that of Comparative Example 1, Comparative Example 2 and the external degradable mulch film, and meets the laying requirements of local cotton crops.

[0151] It should be clear that the various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. The present invention is not limited to the specific steps described above and shown in the figures. In addition, for the sake of simplicity, detailed descriptions of known methods and technologies are omitted here.

[0152] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A multi-layer barrier salt-alkali resistant biodegradable mulch film, characterized in that: It has a five-layer structure of CBABC stacked in sequence, with layer A being a functional resin layer, layer B being a high-barrier mineral powder protective layer, and layer C being a wax protective layer; Wherein, the thickness of the A layer is 4-10 μm, the thickness of the B layer is 1-5 μm, and the thickness of the C layer is 0.1-1 μm.

2. The multi-layer barrier salt-alkali resistant biodegradable mulch film according to claim 1, characterized in that: The A layer is formed by blown film of functional masterbatch A, and the components of the functional masterbatch A include PBAT, PLA, PPC, PBS, PBST, PBSA, chain extender, anti-hydrolysis agent, silicon dioxide, titanium dioxide, ultraviolet stabilizer, ultraviolet absorber, lubricant, and antioxidant.

3. The multi-layer barrier salt-alkali resistant biodegradable mulch film according to claim 1, characterized in that: The B layer is formed by blown film of functional masterbatch B, and the components of the functional masterbatch B include PBAT, barrier inorganic mineral powder, wax powder, antioxidant, coupling agent, and biodegradable carbon black masterbatch.

4. The multi-layer barrier salt-alkali resistant biodegradable mulch film according to claim 1, characterized in that: The C layer is formed by migrating the low molecular weight wax in the B layer to the surface of the film material by infrared thermal migration, and its ingredients include paraffin powder with a melting point below 100° C. and low melting point polyethylene wax.

5. The multi-layer barrier salt-alkali resistant biodegradable ground film according to claim 2, characterized in that: The functional masterbatch A comprises the following raw materials in parts by weight: 40-95 parts of PBAT, 3-30 parts of PLA, 2.5-30 parts of PPC, 0.01-30 parts of PBS, 0.01-30 parts of PBST, 0.01-30 parts of PBSA, 0.01-2 parts of chain extender, 0.01-2 parts of anti-hydrolysis agent, 0.01-5 parts of silicon dioxide, 0.01-5 parts of titanium dioxide, 0.01-5 parts of ultraviolet light stabilizer, 0.01-5 parts of ultraviolet light absorber, 0.01-5 parts of lubricant, and 0.01-5 parts of antioxidant; The chain extender is selected from one or more of ADR4468, KL4370, KL4370B, KL40, CE301, and XY-4370; The anti-hydrolysis agent is selected from one or more of C-768, HMV-5CA-LC, HMV-15CA, H-210, SW100, SW-500, bio362, and SDA3600; The ultraviolet light stabilizer is selected from one or more of UV-801, UV-944, UV-622, and UV-770; The ultraviolet light absorber is selected from one or more of UV-1, UV-P, UV-326, UV-327, UV-328, UV-329, UV-320, UV-360, UV-531, UV-538, UV-571, UV-1157, UV-1164, UV-234, UV-312, UV-928, and UV-3030; The lubricant is selected from one or more of PETS, EBS, PE wax, monoglyceride, erucamide, and oleamide; The antioxidant is selected from one or more of antioxidant 1010, antioxidant 168, antioxidant 626, antioxidant 618, antioxidant 9228, antioxidant B225, and antioxidant B215; The functional masterbatch A is prepared by uniformly mixing the raw material additives using a high-speed mixer and then processing the mixture using a twin-screw extruder.

6. The multi-layer barrier salt-alkali resistant biodegradable ground film according to claim 3, characterized in that: The functional masterbatch B comprises the following raw materials in parts by weight: 20-95 parts of PBAT, 1-80 parts of barrier inorganic mineral powder, 0.01-30 parts of wax powder, 0.01-5 parts of antioxidant, 0.01-5 parts of coupling agent, and 0.01-15 parts of biodegradable carbon black masterbatch. The barrier inorganic mineral powder is selected from one or more of talc powder, mica powder, modified montmorillonite DK2, modified montmorillonite DK4, and modified montmorillonite DK-32B; The wax powder is selected from at least one of paraffin powder and polyethylene wax having a melting point below 100°C; The antioxidant is selected from one or more of antioxidant 1010, antioxidant 1076, antioxidant 1024, antioxidant 1098, antioxidant 245, antioxidant 1135, antioxidant 2246, antioxidant 3114, antioxidant 330, antioxidant 1035, antioxidant 1520, antioxidant 168, antioxidant 626, antioxidant 618, antioxidant 9228, antioxidant B225, and antioxidant B215; The coupling agent is selected from one or more of silane coupling agent KH-550, silane coupling agent KH-560, silane coupling agent KH-570, silane coupling agent KH-151, silane coupling agent JS-8112, silane coupling agent A-171 aluminate coupling agent, and DL411; The functional masterbatch B is prepared by uniformly mixing the raw materials with a high-speed mixer and then processing them with a twin-screw extruder.

7. A method for preparing a multi-layer barrier salt-alkali resistant biodegradable mulch film, comprising processing a multi-layer barrier salt-alkali resistant biodegradable mulch film as claimed in any one of claims 1 to 6, characterized in that: S1. The functional masterbatch A and the functional masterbatch B are put into a BAB three-layer co-extrusion film blowing machine to form a film to obtain a film having a three-layer stacked structure of BAB; The blow molding blow ratio is 3; S2. The membrane material with the three-layer structure of BAB prepared in S1 is drawn into the drawing section, and in the drawing section, an infrared heating device and an air cooling device are used to thermally migrate the low molecular wax in the B layer to the outer layer to form the C layer, thereby forming a high-barrier, salt-alkali-resistant biodegradable ground membrane with a five-layer structure of CBABC stacked in sequence.

8. The method for preparing a multi-layer barrier salt-alkali resistant biodegradable mulch film as claimed in claim 7, wherein the heating temperature of the infrared heating device is 85-95°C.

9. A method for preparing a multi-layer barrier salt-alkali resistant biodegradable ground film as claimed in claim 7, wherein the film blowing thickness of the air blowing cooling device is 7-20 μm.

10. Application of the multi-layer barrier salt-alkali resistant biodegradable mulch film as described in claims 1 to 9 in farmland.

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