CN106363898A - Preparation method of three-layer co-extrusion whole-biodegradable mulching film and the three-layer co-extrusion whole-biodegradable mulching film - Google Patents

Abstract

The invention provides a preparation method of a three-layer co-extruded fully biodegradable mulch film and a three-layer co-extruded fully biodegradable mulch film. In the preparation method of the three-layer co-extruded fully biodegradable mulch film of the present invention, the raw material components of the outer layer, the middle layer and the inner layer are respectively mixed uniformly, and a masterbatch is made by using a twin-screw extruder, and then blown by three-layer co-extrusion The molding process produces a three-layer co-extruded fully biodegradable mulch film consisting of an outer layer, a middle layer and an inner layer. The inner layer uses a material formula with good opening and film-forming properties, and the middle layer uses a material formula with high barrier properties. The outer layer adopts a soft and tough material formula with UV resistance, which can improve the shortcomings of biodegradable mulch film, such as difficult forming, poor barrier performance, and poor opening, and endow it with good mechanical properties, biodegradation controllability, and heat preservation and moisture retention. Excellent performance such as good effect can realize large-scale popularization and application of degradable plastic film.

Description

Preparation method of three-layer co-extruded fully biodegradable mulch film and three-layer co-extruded fully biodegradable Mulch

technical field

The invention relates to the field of biodegradable mulch, in particular to a preparation method of a three-layer co-extruded fully biodegradable mulch and a three-layer co-extruded fully biodegradable mulch.

Background technique

Agricultural mulch film has the functions of increasing ground temperature, water retention, soil protection, pest control, and weed growth inhibition, which can increase crop production and income. However, since the introduction of plastic film in China, a large number of polyethylene (PE) plastic films have been used in crop production. While PE plastic film has brought huge benefits to agriculture, it has also brought serious "white pollution" to the ecological environment. Due to the degradation of PE plastic film It takes a long time and remains on the surface and soil after the crops are harvested, which is difficult to degrade, causing unpredictable pollution and damage to the soil, and also causing a substantial reduction in crop production.

The fully biodegradable mulch material is completely biodegraded into water, carbon dioxide and small molecular substances within 60-180 days after the film is laid, and will not pollute the soil, and the degraded products can be used as crop fertilizers, which are easy for crops to grow. , is a low-carbon, environmentally friendly material. At present, there are dozens of biodegradable mulch films in the world, such as hydroxy fatty acid ester (salt) polymers (PHAs), polylactic acid (PLA), polycaprolactone (PCL), polybutylene succinate (PBS), etc. ), polybutylene adipate/terephthalate (PBAT), polypropylene carbonate (PPC), etc.

Based on the non-degradability of PE mulch film and the heat preservation and water retention effect of the mulch film, many researches on biodegradable agricultural mulch film have been carried out at home and abroad. Patent document CN 104403294A mentions PPC and PBS multilayer barrier film, and uses modified nanometer light calcium carbonate and chain extender to modify PBS and PPC, so as to prepare a multilayer film with layers between 2 and 2048. However, the high crystallinity of PBS makes the material significantly brittle when stored at room temperature, and the decomposition rate of mulch film will be faster under the conditions of sun and rain, thus limiting the promotion and use of PBS in agricultural mulch film. The patent document CN 103709687 A discloses a composition containing PBAT and its preparation method and PBAT fully biodegradable mulch film, by adding modified high-permeable talc powder and silicon dioxide and/or SR100 from Ciba to PBAT The opening of the PBAT mulch made from the PBAT composition is improved. However, some data prove that the water resistance of PBAT is slightly inferior to that of PBS, that is, its water vapor transmission rate is large, and the moisturizing and water-proof effect is poor when used as a mulch, so it cannot be used alone use.

In view of the deficiency of the current biodegradable mulch film in heat preservation, entropy preservation and barrier performance, it is necessary to propose a new biodegradable mulch film and its corresponding preparation method.

Contents of the invention

The purpose of the present invention is to provide a method for preparing a three-layer co-extruded fully biodegradable mulch film, which can improve the shortcomings of biodegradable mulch film such as difficult molding, poor barrier performance, and poor opening, and endow it with good mechanical properties and biodegradable properties. Excellent properties such as controllability and heat preservation and moisture retention effect, so as to realize the large-scale promotion and application of degradable plastic film.

The purpose of the present invention is also to provide a three-layer co-extruded fully biodegradable mulch film, which has a simple preparation method, good mechanical properties, controllable biodegradation, and good heat preservation and moisture conservation effects, and can be popularized and applied on a large scale.

In order to achieve the above object, the present invention first provides a preparation method of a three-layer co-extruded fully biodegradable mulch film. The raw material components of the outer layer, the middle layer, and the inner layer are mixed uniformly, and the masterbatch is made by a twin-screw extruder. Then, a three-layer co-extrusion fully biodegradable mulch film including an outer layer, a middle layer and an inner layer is prepared through a three-layer co-extrusion blow molding process;

The outer layer includes the following raw material components: 80-95wt% of PBAT, 2-10wt% of plasticizer, 0.5-3wt% of crosslinking agent, 0.5-2wt% of antioxidant, 0.5-1.5wt% of lubricant, light Stabilizer 0.5-2wt%;

The intermediate layer includes the following raw material components: PPC 60-90wt%, PBAT 10-40wt%, plasticizer 2-10wt%, crosslinking agent 0.5-3wt%, antioxidant 0.5-2wt%, lubricant 0.5 -1.5wt%, light stabilizer 0.5-2wt%;

The inner layer includes the following raw material components: PLA 10-40wt%, PBAT 50-80wt%, inorganic filler 2-15wt%, plasticizer 2-10wt%, crosslinking agent 0.5-3wt%, antioxidant 0.5 -2wt%, lubricant 0.5-1.5wt%, light stabilizer 0.5-2wt%.

The step of uniformly mixing the raw material components of the outer layer is as follows: weighing the raw material components of the outer layer according to the proportion, placing the weighed PBAT in a high-speed mixer, adding the weighed plasticizer and stirring for 1 -2min, then add the weighed cross-linking agent, antioxidant, lubricant, light stabilizer, continue to stir for 8-12min and then take out of the pot, so as to mix the raw material components of the outer layer evenly, wherein the mixing temperature is 60- Between 80°C;

The step of uniformly mixing the raw material components of the middle layer is as follows: weigh the raw material components of the middle layer according to the proportion, place the weighed PPC and PBAT in a high-speed mixer, add the weighed plasticizer and stir 1-2min, then add the weighed cross-linking agent, antioxidant, lubricant, light stabilizer, continue to stir for 8-12min and then take out of the pot, so as to mix the raw material components of the middle layer evenly, wherein the mixing temperature is 60 Between -80°C;

The steps of uniformly mixing the raw material components of the inner layer are as follows: weigh the raw material components of the inner layer according to the proportion, stir the weighed inorganic filler in a high-speed mixer, and add a part of the weighed inorganic filler during the stirring process. Plasticizer, the stirring time is 18-22min, to treat the surface of the inorganic filler, pack it after stirring evenly, then place the weighed PLA and PBAT in the high-speed mixer, add the remaining weighed plasticizer Stir the plasticizer for 1-2 minutes, then add the weighed cross-linking agent, antioxidant, lubricant, light stabilizer and surface-treated inorganic filler, continue stirring for 8-12 minutes, and then take it out of the pot, so that the raw materials in the inner layer are combined Mix evenly, and the mixing temperature is between 60-80°C.

In the step of using a twin-screw extruder to make masterbatches, the temperature of the twin-screw extruder is set at 130-190°C, the screw speed is 40-200rpm, and the material is cooled and then pelletized and packaged;

In the three-layer co-extrusion blow molding process, the material extrusion speeds of the three extruders corresponding to the outer layer, the middle layer, and the inner layer respectively are 0.8-1.2:0.8-1.2:1, and the processing temperature is set to 150-220°C, the screw speed is 20-80rpm, and the pulling speed of the film pulling device is 10-50m/min.

The thickness of the three-layer co-extruded fully biodegradable plastic film is 10-15 μm.

Described PPC, PBAT, PLA are the materials through drying treatment;

The viscosity-average molecular weight of the PPC is 70,000-180,000;

The number average molecular weight of the PBAT is 55,000-200,000;

The content of L configuration in the PLA is greater than 88%, the optical purity of the PLA is 95%, and the viscosity-average molecular weight of the PLA is 50,000-700,000.

The mesh number of the inorganic filler is more than or equal to 3000 mesh, and the inorganic filler is at least one of talcum powder, silicon dioxide, and boron nitride;

The plasticizer is at least one of polyethylene glycol and acetyl tri-n-butyl citrate, wherein the molecular weight of polyethylene glycol is 200-2000g/mol;

The crosslinking agent is at least one of diphenylmethane diisocyanate, toluene-2,4-diisocyanate, ADR-4380, ADR-4370, and ADR-4300;

The light stabilizer is one or both of UV234, UV326, UV-P, UV371, SORB2020, and its molecular weight is between 300-4000g/mol;

The antioxidant is one or both of antioxidant 1010, antioxidant 168, antioxidant 1076, antioxidant DLTP, and antioxidant 126;

Described lubricant is pentaerythritol stearate.

The present invention also provides a three-layer co-extrusion fully biodegradable mulch film, which is produced by a three-layer co-extrusion blow molding process, including a middle layer, and inner and outer layers respectively located on both sides of the middle layer;

The outer layer includes the following raw material components: 80-95wt% of PBAT, 2-10wt% of plasticizer, 0.5-3wt% of crosslinking agent, 0.5-2wt% of antioxidant, 0.5-1.5wt% of lubricant, light Stabilizer 0.5-2wt%;

The intermediate layer includes the following raw material components: PPC 60-90wt%, PBAT 10-40wt%, plasticizer 2-10wt%, crosslinking agent 0.5-3wt%, antioxidant 0.5-2wt%, lubricant 0.5 -1.5wt%, light stabilizer 0.5-2wt%;

The inner layer includes the following raw material components: PLA 10-40wt%, PBAT 50-80wt%, inorganic filler 2-15wt%, plasticizer 2-10wt%, crosslinking agent 0.5-3wt%, antioxidant 0.5 -2wt%, lubricant 0.5-1.5wt%, light stabilizer 0.5-2wt%.

In the three-layer co-extrusion blow molding process, the material extrusion speeds of the three extruders respectively corresponding to the outer layer, the middle layer, and the inner layer are 0.8-1.2:0.8-1.2:1, and the three layers have a total of The thickness of the extruded biodegradable plastic film is 10-15 μm.

Described PPC, PBAT, PLA are the materials through drying treatment;

The viscosity-average molecular weight of the PPC is 70,000-180,000;

The number average molecular weight of the PBAT is 55,000-200,000;

The content of L configuration in the PLA is greater than 88%, the optical purity of the PLA is 95%, and the viscosity-average molecular weight of the PLA is 50,000-700,000.

The mesh number of the inorganic filler is more than or equal to 3000 mesh, and the inorganic filler is at least one of talcum powder, silicon dioxide, and boron nitride;

The plasticizer is at least one of polyethylene glycol and acetyl tri-n-butyl citrate, wherein the molecular weight of polyethylene glycol is 200-2000g/mol;

The crosslinking agent is at least one of diphenylmethane diisocyanate, toluene-2,4-diisocyanate, ADR-4380, ADR-4370, and ADR-4300;

The light stabilizer is one or both of UV234, UV326, UV-P, UV371, SORB2020, and its molecular weight is between 300-4000g/mol;

The antioxidant is one or both of antioxidant 1010, antioxidant 168, antioxidant 1076, antioxidant DLTP, and antioxidant 126;

Described lubricant is pentaerythritol stearate.

Beneficial effects of the present invention: the preparation method of the three-layer co-extruded fully biodegradable mulch film of the present invention, the raw material components of the outer layer, the middle layer, and the inner layer are mixed uniformly, and the masterbatch is made by a twin-screw extruder, and then passed through The three-layer co-extrusion blow molding process produces a three-layer co-extruded fully biodegradable mulch film consisting of an outer layer, a middle layer and an inner layer. Among them, the inner layer adopts a material formula with good opening and film-forming properties, and the middle layer is a barrier layer. , using PPC as the base material which is difficult to form but has good barrier properties, adopts a material formula with high barrier properties, and the outer layer adopts a soft and tough material formula with UV resistance, which can improve the difficulty of forming and barrier properties of biodegradable mulches The shortcomings of poor opening and poor opening, and endow it with good mechanical properties, controllable biodegradation, and good heat preservation and moisture retention, so as to realize the large-scale promotion and application of degradable mulch. The three-layer co-extruded fully biodegradable mulch film of the present invention has a simple preparation method, has excellent properties such as good mechanical properties, controllable biodegradation, and good heat preservation and moisture conservation effects, and can be popularized and applied on a large scale.

Description of drawings

In order to further understand the features and technical content of the present invention, please refer to the following detailed description and accompanying drawings of the present invention. However, the accompanying drawings are provided for reference and illustration only, and are not intended to limit the present invention.

In the attached picture,

Fig. 1 is the structural representation of three-layer co-extruded fully biodegradable mulch film of the present invention;

Fig. 2 is a schematic diagram of extrusion of materials corresponding to the outer layer, the middle layer and the inner layer through the annular co-extrusion die in the three-layer co-extrusion blow molding process.

detailed description

In order to further illustrate the technical means adopted by the present invention and its effects, the following describes in detail in conjunction with preferred embodiments of the present invention and accompanying drawings.

The preparation method of the three-layer co-extruded fully biodegradable plastic film provided by the present invention is to mix the raw material components of the outer layer, the middle layer, and the inner layer evenly, and use a twin-screw extruder to make a masterbatch, and then blow it through the three-layer co-extrusion. The three-layer co-extruded fully biodegradable mulch film comprising the outer layer, the middle layer and the inner layer as shown in Figure 1 is produced by molding process;

The outer layer includes the following raw material components: 80-95wt% of PBAT, 2-10wt% of plasticizer, 0.5-3wt% of crosslinking agent, 0.5-2wt% of antioxidant, 0.5-1.5wt% of lubricant, light Stabilizer 0.5-2wt%;

The intermediate layer includes the following raw material components: PPC 60-90wt%, PBAT 10-40wt%, plasticizer 2-10wt%, crosslinking agent 0.5-3wt%, antioxidant 0.5-2wt%, lubricant 0.5 -1.5wt%, light stabilizer 0.5-2wt%;

The inner layer includes the following raw material components: PLA 10-40wt%, PBAT 50-80wt%, inorganic filler 2-15wt%, plasticizer 2-10wt%, crosslinking agent 0.5-3wt%, antioxidant 0.5 -2wt%, lubricant 0.5-1.5wt%, light stabilizer 0.5-2wt%.

Specifically, the step of uniformly mixing the raw material components of the outer layer is specifically weighing the raw material components of the outer layer according to the proportion, placing the weighed PBAT in a high-speed mixer, and adding the weighed plasticizer After stirring for 1-2 minutes, add the weighed cross-linking agent, antioxidant, lubricant and light stabilizer, continue stirring for 8-12 minutes, and then take out of the pot, so as to mix the raw material components of the outer layer evenly. Between 60-80°C.

Specifically, the step of uniformly mixing the raw material components of the middle layer is specifically weighing the raw material components of the middle layer according to the proportion, placing the weighed PPC and PBAT in a high-speed mixer, and adding the weighed plasticizer Stir for 1-2 minutes after the preparation, then add the weighed cross-linking agent, antioxidant, lubricant, and light stabilizer, continue stirring for 8-12 minutes, and then take it out of the pot, so as to mix the raw material components of the middle layer evenly. The temperature is between 60-80°C.

Specifically, the step of uniformly mixing the raw material components of the inner layer is as follows: weighing the raw material components of the inner layer according to the proportion, stirring the weighed inorganic filler in a high-speed mixer, and adding a part of The weighed plasticizer is used to treat the surface of the inorganic filler. The stirring time is 18-22min. After stirring evenly, pack it for use. Then place the weighed PLA and PBAT in a high-speed mixer, and add the remaining weighed Stir the plasticizer for 1-2 minutes, then add the weighed cross-linking agent, antioxidant, lubricant, light stabilizer and surface-treated inorganic filler, continue stirring for 8-12 minutes, and then take it out of the pot, so that the inner layer The raw material components are mixed evenly, and the mixing temperature is between 60-80°C.

Specifically, in the step of using a twin-screw extruder to make masterbatches, the temperature of the twin-screw extruder is set between 130-190°C, the screw speed is 40-200rpm, and the material is cooled and then pelletized and packaged .

Specifically, as shown in Figure 2, the three-layer co-extrusion blow molding process is specifically, after the prepared masterbatches corresponding to the outer layer, middle layer, and inner layer are extruded by 3 extruders respectively, and then enter The ring-shaped co-extrusion die forms a three-layer film extrusion, and the compressed air is blown from the cooling air duct in the center of the die to blow the film into a cylindrical film or film bubble, cooled by internal and external air, and then passed through the film rotating traction device , the folded film is led to the winding machine through the idle guide roller. Among them, the material extrusion speed of the three extruders corresponding to the outer layer, the middle layer and the inner layer is 0.8-1.2:0.8-1.2:1, the processing temperature is set at 150-220°C, and the screw speed is 20 -80rpm, the pulling speed of the film by the film rotating pulling device is 10-50m/min.

Specifically, the thickness of the three-layer co-extrusion fully biodegradable mulch film produced by the three-layer co-extrusion blow molding process is 10-15 μm.

Specifically, the PPC, PBAT, and PLA need to be dried before being processed: PPC is placed in an oven at 60°C for 2-4 hours, and PLA and PBAT are placed in an oven at 80°C for 2-4 hours for backup. use.

Specifically, the viscosity-average molecular weight of the PPC is 70,000-180,000.

Specifically, the number average molecular weight of the PBAT is 55,000-200,000.

Specifically, the content of the L configuration in the PLA is greater than 88%, the optical purity of the PLA is 95%, and the viscosity-average molecular weight of the PLA is 50,000-700,000.

Specifically, the inorganic filler is at least one of talcum powder, silicon dioxide, and boron nitride.

Specifically, the mesh number of the inorganic filler is ≥ 3000 mesh, so as to increase the specific surface area and surface adsorption capacity of the inorganic filler, and improve its dispersion effect. In addition, before mixing the raw material components of the inner layer, the inorganic filler also needs to It is surface treated with a part of plasticizer.

Specifically, the plasticizer is at least one of polyethylene glycol (PEG) and acetyl tri-n-butyl citrate (ATBC), wherein the molecular weight of polyethylene glycol is 200-2000 g/mol.

Specifically, the molecules of the crosslinking agent have active functional groups that can react with hydroxyl groups, carboxyl groups, etc. of polyester plastics, and re-coupling and degraded molecular chains during processing can also play a role in capping and crosslinking, improving Weight average molecular weight, the crosslinking agent described in the present invention is at least one of diphenylmethane diisocyanate (MDI), toluene-2,4-diisocyanate (TDI), ADR-4380, ADR-4370, ADR-4300 kind.

Specifically, the light stabilizer is one or two of UV234, UV326, UV-P, UV371, and SORB2020, and its molecular weight is between 300-4000 g/mol.

Specifically, the antioxidant is one or two of antioxidant 1010, antioxidant 168, antioxidant 1076, antioxidant DLTP, and antioxidant 126.

Specifically, the lubricant used in the present invention is pentaerythritol stearate, white bead-shaped particles with a molecular weight of 1202, which can significantly improve transparency and surface smoothness.

The preparation method of the three-layer co-extruded fully biodegradable plastic film of the present invention is to prepare a three-layer co-extruded fully biodegradable plastic film comprising an outer layer, a middle layer and an inner layer through a three-layer co-extruded blow molding process, wherein the inner layer adopts The material formula with good opening and film-forming properties is based on PBAT, which is a PBAT composite film with good opening properties. The middle layer adopts a material formula with high barrier properties, and PPC is used as the base material. Composite film, the outer layer adopts a soft and tough material formula with UV resistance, which is a PBAT composite film containing UV additives, which can improve the shortcomings of biodegradable mulch film, such as difficult forming, poor barrier performance, and poor opening, and endow It has good mechanical properties, controllable biodegradation, and good heat preservation and moisture conservation effects, which can realize the large-scale popularization and application of degradable plastic film.

The present invention also provides a three-layer co-extrusion fully biodegradable mulch film, which is produced by a three-layer co-extrusion blow molding process, including a middle layer, and inner and outer layers respectively located on both sides of the middle layer;

The outer layer includes the following raw material components: 80-95wt% of PBAT, 2-10wt% of plasticizer, 0.5-3wt% of crosslinking agent, 0.5-2wt% of antioxidant, 0.5-1.5wt% of lubricant, light Stabilizer 0.5-2wt%;

The intermediate layer includes the following raw material components: PPC 60-90wt%, PBAT 10-40wt%, plasticizer 2-10wt%, crosslinking agent 0.5-3wt%, antioxidant 0.5-2wt%, lubricant 0.5 -1.5wt%, light stabilizer 0.5-2wt%;

The inner layer includes the following raw material components: PLA 10-40wt%, PBAT 50-80wt%, inorganic filler 2-15wt%, plasticizer 2-10wt%, crosslinking agent 0.5-3wt%, antioxidant 0.5 -2wt%, lubricant 0.5-1.5wt%, light stabilizer 0.5-2wt%.

Specifically, during the preparation process of the three-layer co-extruded fully biodegradable mulch film, the material extrusion speeds of the three extruders corresponding to the outer layer, the middle layer, and the inner layer respectively are 0.8-1.2:0.8-1.2:1 , the thickness of the three-layer co-extruded fully biodegradable plastic film is 10-15 μm.

Specifically, the PPC, PBAT, and PLA are all dried materials.

Specifically, the viscosity-average molecular weight of the PPC is 70,000-180,000.

Specifically, the number average molecular weight of the PBAT is 55,000-200,000.

Specifically, the content of the L configuration in the PLA is greater than 88%, the optical purity of the PLA is 95%, and the viscosity-average molecular weight of the PLA is 50,000-700,000.

Specifically, the mesh number of the inorganic filler is ≥3000 mesh, and the inorganic filler is at least one of talcum powder, silicon dioxide, and boron nitride.

Specifically, the plasticizer is at least one of polyethylene glycol and acetyl tri-n-butyl citrate, wherein the molecular weight of polyethylene glycol is 200-2000 g/mol.

Specifically, the crosslinking agent is at least one of diphenylmethane diisocyanate, toluene-2,4-diisocyanate, ADR-4380, ADR-4370, and ADR-4300.

Specifically, the light stabilizer is one or two of UV234, UV326, UV-P, UV371, and SORB2020, and its molecular weight is between 300-4000 g/mol.

Specifically, the antioxidant is one or two of antioxidant 1010, antioxidant 168, antioxidant 1076, antioxidant DLTP, and antioxidant 126.

Specifically, the lubricant is pentaerythritol stearate.

The three-layer co-extruded fully biodegradable mulch film of the present invention uses the PBAT composite film containing antioxidants and UV composite additives as the outer layer, which provides the most basic mechanical performance guarantee for the popularization and application of biodegradable mulch films; , PPC film with good barrier performance and difficult to form is placed in the middle layer, which not only realizes the benign processing of PPC, but also makes the biodegradable film have good barrier performance. The composite material containing PBAT, PLA and inorganic filler is placed in the inner layer to ensure The easy-to-open performance is improved, so that the UV resistance, barrier properties and open properties are soft and complementary, and a good interface effect between layers is ensured by crosslinking agents and plasticizers.

In order to deepen the understanding of the present invention, the present invention will be described in further detail below in conjunction with the examples, wherein the raw materials, parameters and equipment involved are not the only choice for realizing this method, and the raw materials, parameters and equipment can be selected according to needs in actual operation or adjust. These examples are only used to explain the present invention, and do not constitute a limitation to the protection scope of the present invention.

1. Embodiment 1

The raw material formula is as follows:

Among them, PPC and PBAT need to be dried in an oven at 60°C and 80°C for 2 hours before processing; the above materials are weighed according to the above ratio and placed in a high-speed mixer, and the order of feeding the materials is substrate (PPC, PBAT) , plasticizer (ATBC), powder additives (UV329, MDI, KY1010, lubricant), the mixing temperature is between 60-80 ° C, and the mixing time is 10 minutes.

The uniformly mixed material is lowered into the twin-screw extruder, the temperature of the extruder is set between 130-190°C, the screw speed is 40-200rpm, the material is cooled, then pelletized and packaged.

2. Embodiment 2

The raw material formula is as follows:

Among them, PPC and PBAT need to be dried in an oven at 60°C and 80°C for 2 hours before processing; the above materials are weighed according to the proportion and placed in a high-speed mixer. Plastic agent (PEG), powder additives (UV326, MDI, KY1010, lubricant), the mixing temperature is between 60-80°C, and the mixing time is 10 minutes.

The uniformly mixed material is lowered into the twin-screw extruder, the temperature of the extruder is set between 130-190°C, the screw speed is 40-200rpm, the material is cooled, then pelletized and packaged.

3. Embodiment 3

The raw material formula is as follows:

Among them, PLA and PBAT need to be dried in an oven at 80°C for 2 hours before processing; boron nitride needs to be surface treated before being mixed with the substrate, specifically, boron nitride is first stirred in a high-speed mixer, and during the stirring process Add a part of ATBC to the mixture, stir for 18-22min, pack it for use after stirring evenly; then place the above materials in a high-speed mixer according to the ratio of the above materials and mix them, and the order of feeding the materials is base material (PLA, PBAT), plasticizer (ATBC), powder additives (ADR4300, KY1010, lubricant, UV-P), surface-treated boron nitride, the mixing temperature is between 60-80°C, and the mixing time is 15min; wherein, for 2wt% in the raw material formula ATBC, 1wt% of ATBC is used for surface treatment of boron nitride, and another 1wt% of ATBC is added directly when mixing with the substrate.

The uniformly mixed material is lowered into the twin-screw extruder, the temperature of the extruder is set at 140-210°C, the screw speed is 40-200rpm, the material is cooled, then pelletized and packaged.

4. Embodiment 4

The raw material formula is as follows:

Among them, PLA and PBAT need to be dried in an oven at 80°C for 2 hours before processing; SiO ₂ needs to be surface treated before mixing with the substrate. Specifically, SiO ₂ is first stirred in a high-speed mixer and added A part of PEG, stirred for 18-22min, packed evenly before use; then according to the ratio of the above materials, the above materials were placed in a high-speed mixer for mixing, and the order of feeding the materials was base material (PLA, PBAT), plasticizer (PEG ), powder additives (ADR4370, KY1010, lubricant, SORB2020), surface-treated SiO ₂ , the mixing temperature is between 60-80°C, and the mixing time is 15 minutes; wherein, for 2wt% PEG in the raw material formula, 1wt% of PEG was used for surface treatment of _SiO2 , and another 1 wt% of PEG was added directly when mixing with the substrate.

The uniformly mixed material is lowered into the twin-screw extruder, the temperature of the extruder is set at 140-210°C, the screw speed is 40-200rpm, the material is cooled, then pelletized and packaged.

5. Embodiment 5

The raw material formula is as follows:

Among them, PLA and PBAT need to be pre-dried in an oven at 80°C for 2 hours before processing; Talc needs to be surface treated before mixing with the substrate. Specifically, Talc is first stirred in a high-speed mixer, and a part of PEG, stirred for 18-22min, and packed for use after stirring evenly; then, according to the ratio of the above materials, the above materials were placed in a high-speed mixer for mixing, and the order of feeding the materials was base material (PLA, PBAT), plasticizer (PEG), Powder additives (ADR4370, KY1010, lubricants, SORB2020), surface-treated Talc, the mixing temperature is between 60-80 ° C, and the mixing time is 15 minutes; among them, for 2wt% PEG in the raw material formula, 1wt% PEG is used For surface treatment of Talc, an additional 1 wt% of PEG was added directly while mixing with the substrate.

The uniformly mixed material is lowered into the twin-screw extruder, the temperature of the extruder is set at 140-210°C, the screw speed is 40-200rpm, the material is cooled, then pelletized and packaged.

6. Embodiment 6

The raw material formula is as follows:

Among them, PBAT needs to be dried in an oven at 80°C for 2 hours before processing; the above materials are weighed according to the proportion and placed in a high-speed mixer, and the order of feeding the materials is base material (PBAT), plasticizer (ATBC), powder additive (ADR4380, KY1010, lubricant, SORB2020, UV326), the mixing temperature is between 60-80°C, and the mixing time is 15 minutes.

The uniformly mixed material is lowered into the twin-screw extruder, the temperature of the extruder is set between 120-180°C, the screw speed is 40-200rpm, the material is cooled, then pelletized and packaged.

7. Embodiment 7

The raw material formula is as follows:

Among them, PBAT needs to be dried in an oven at 80°C for 2 hours before processing; the above materials are weighed according to the proportion and placed in a high-speed mixer. The order of feeding the materials is base material (PBAT), plasticizer (PEG), and powder additives. (ADR4380, KY1010, lubricant, UV-P, UV371), the mixing temperature is between 60-80°C, and the mixing time is 15 minutes.

The uniformly mixed material is lowered into the twin-screw extruder, the temperature of the extruder is set between 120-180°C, the screw speed is 40-200rpm, the material is cooled, then pelletized and packaged.

8. Embodiment 8

As shown in Figure 2, a three-layer co-extrusion fully biodegradable mulch film is obtained through a three-layer co-extrusion blow molding process. Layer, inner layer materials, and the extrusion speed ratio of the three is 1:0.9:0.95.

A: embodiment 6;

B: Example 1;

C: Example 3.

In the three-layer co-extrusion blow molding process, the above materials are placed in three extruders according to the requirements, the processing temperature is set at 150-220°C, the screw speed is 20-80rpm, and the traction speed of the film traction device is 10- 50m/min.

Table I:

9. Embodiment 9

As shown in Figure 2, a three-layer co-extrusion fully biodegradable mulch film is obtained through a three-layer co-extrusion blow molding process. Layer and inner layer materials, the extrusion speed of the three is 0.95:0.95:1.1.

A: embodiment 6;

B: embodiment 2;

C: Example 4.

In the three-layer co-extrusion blow molding process, the above materials are respectively placed in three extruders according to the requirements, the processing temperature is set at 150-220°C, the screw speed is 20-80rpm, and the traction speed is 10-50m/min.

Table II:

10. Embodiment 10

As shown in Figure 2, a three-layer co-extrusion fully biodegradable mulch film is obtained through a three-layer co-extrusion blow molding process. The extrusion speed of the material of layer and inner layer is 0.95:1.05:0.9.

A: Example 6,

B: Example 2,

C: Example 3.

The above materials are placed in three extruders as required, the processing temperature is set at 150-220°C, the screw speed is 20-80rpm, and the traction speed is 10-50m/min.

Table three:

11. Embodiment 11

As shown in Figure 2, a three-layer co-extrusion fully biodegradable mulch film is obtained through a three-layer co-extrusion blow molding process. Layer and inner layer materials, the extrusion speed of the three is 0.9:1.1:1.

A: Example 6,

B: Example 1,

C: Example 4.

In the three-layer co-extrusion blow molding process, the above materials are respectively placed in three extruders according to the requirements, the processing temperature is set at 150-220°C, the screw speed is 20-80rpm, and the traction speed is 10-50m/min.

Table four:

12. Example 12

As shown in Figure 2, a three-layer co-extrusion fully biodegradable mulch film is obtained through a three-layer co-extrusion blow molding process. The extrusion speed of the material of layer and inner layer is 1.05:1:0.95.

A: Example 6,

B: Example 2,

C: Example 5.

In the three-layer co-extrusion blow molding process, the above materials are respectively placed in three extruders according to the requirements, the processing temperature is set at 150-220°C, the screw speed is 20-80rpm, and the traction speed is 10-50m/min.

Table five:

13. Embodiment 13

As shown in Figure 2, a three-layer co-extrusion fully biodegradable mulch film is obtained through a three-layer co-extrusion blow molding process. Layer and inner layer materials, the extrusion speed of the three is 1.1:1.05:0.9.

A: Example 7,

B: Example 2,

C: Example 5.

In the three-layer co-extrusion blow molding process, the above materials are respectively placed in three extruders according to the requirements, the processing temperature is set at 150-220°C, the screw speed is 20-80rpm, and the traction speed is 10-50m/min.

Table six:

14. Embodiment 14

As shown in Figure 2, a three-layer co-extrusion fully biodegradable mulch film is obtained through a three-layer co-extrusion blow molding process. Layer and inner layer materials, the extrusion speed of the three is 1:1:1.

A: Example 7,

B: Example 1,

C: Example 5.

In the three-layer co-extrusion blow molding process, the above materials are respectively placed in three extruders according to the requirements, the processing temperature is set at 150-220°C, the screw speed is 20-80rpm, and the traction speed is 10-50m/min.

Table seven:

15. Comparative example

PE film (type 641S).

Table Eight:

From the data analysis in Tables 1 to 8, it can be seen that the three-layer co-extruded fully biodegradable mulch film prepared in the above-mentioned Examples 8-14 has met the requirements of general mulch film in terms of mechanical properties, use effect and heat preservation and moisturizing. Moreover, the three-layer co-extruded fully biodegradable mulch film of the present invention can be found to rupture within 30-60 days after laying tests, and the mulch film can be completely degraded within 180 days.

To sum up, the preparation method of the three-layer co-extruded fully biodegradable mulch film of the present invention mixes the raw material components of the outer layer, the middle layer, and the inner layer respectively, and uses a twin-screw extruder to make a masterbatch, and then passes through three A three-layer co-extruded fully biodegradable film consisting of an outer layer, a middle layer and an inner layer is produced by a multi-layer co-extrusion blow molding process. Using PPC as the base material which is difficult to form but has good barrier properties, the material formula with high barrier properties is used, and the outer layer is made of soft and tough material formula with UV resistance, which can improve the difficulty of forming biodegradable mulches, poor barrier properties, The shortcomings of poor opening, and endow it with good mechanical properties, biodegradation controllability and good heat preservation and moisture retention effect, and then realize the large-scale promotion and application of degradable mulch film. The three-layer co-extruded fully biodegradable mulch film of the present invention has a simple preparation method, has excellent properties such as good mechanical properties, controllable biodegradation, and good heat preservation and moisture conservation effects, and can be popularized and applied on a large scale.

As mentioned above, for those of ordinary skill in the art, other various corresponding changes and modifications can be made according to the technical scheme and technical concept of the present invention, and all these changes and modifications should belong to the appended claims of the present invention scope of protection.

Claims (10)

1. A preparation method for a three-layer co-extruded fully biodegradable mulch film, characterized in that, the raw material components of the outer layer, the middle layer, and the inner layer are mixed uniformly respectively, and a twin-screw extruder is used to make a masterbatch, and then passed through three Three-layer co-extrusion fully biodegradable mulch film including outer layer, middle layer and inner layer is produced by layer co-extrusion blow molding process; The outer layer includes the following raw material components: 80-95wt% of PBAT, 2-10wt% of plasticizer, 0.5-3wt% of crosslinking agent, 0.5-2wt% of antioxidant, 0.5-1.5wt% of lubricant, light Stabilizer 0.5-2wt%; The intermediate layer includes the following raw material components: PPC 60-90wt%, PBAT 10-40wt%, plasticizer 2-10wt%, crosslinking agent 0.5-3wt%, antioxidant 0.5-2wt%, lubricant 0.5 -1.5wt%, light stabilizer 0.5-2wt%; The inner layer includes the following raw material components: PLA 10-40wt%, PBAT 50-80wt%, inorganic filler 2-15wt%, plasticizer 2-10wt%, crosslinking agent 0.5-3wt%, antioxidant 0.5 -2wt%, lubricant 0.5-1.5wt%, light stabilizer 0.5-2wt%. 2. The preparation method of three-layer co-extruded fully biodegradable mulch film as claimed in claim 1, is characterized in that, the step of mixing the raw material components of the outer layer is specifically, weighing the raw material components of the outer layer according to the proportioning ratio , put the weighed PBAT in the high-speed mixer, add the weighed plasticizer and stir for 1-2min, then add the weighed crosslinking agent, antioxidant, lubricant, light stabilizer, and continue stirring Take it out of the pot after 8-12 minutes, so that the raw material components of the outer layer are mixed evenly, and the mixing temperature is between 60-80°C; The step of uniformly mixing the raw material components of the middle layer is as follows: weigh the raw material components of the middle layer according to the proportion, place the weighed PPC and PBAT in a high-speed mixer, add the weighed plasticizer and stir 1-2min, then add the weighed cross-linking agent, antioxidant, lubricant, light stabilizer, continue to stir for 8-12min and then take out of the pot, so as to mix the raw material components of the middle layer evenly, wherein the mixing temperature is 60 Between -80°C; The steps of uniformly mixing the raw material components of the inner layer are as follows: weigh the raw material components of the inner layer according to the proportion, stir the weighed inorganic filler in a high-speed mixer, and add a part of the weighed inorganic filler during the stirring process. Plasticizer, the stirring time is 18-22min, to treat the surface of the inorganic filler, pack it after stirring evenly, then place the weighed PLA and PBAT in the high-speed mixer, add the remaining weighed plasticizer Stir the plasticizer for 1-2 minutes, then add the weighed cross-linking agent, antioxidant, lubricant, light stabilizer and surface-treated inorganic filler, continue stirring for 8-12 minutes, and then take it out of the pot, so that the raw materials in the inner layer are combined Mix evenly, and the mixing temperature is between 60-80°C. 3. the preparation method of three-layer co-extrusion full biodegradable mulch film as claimed in claim 1 is characterized in that, in the step that adopts twin-screw extruder to make masterbatch, the temperature of described twin-screw extruder is set to Between 130-190°C, the screw speed is 40-200rpm, the material is cooled and then pelletized and packed; In the three-layer co-extrusion blow molding process, the material extrusion speeds of the three extruders corresponding to the outer layer, the middle layer, and the inner layer respectively are 0.8-1.2:0.8-1.2:1, and the processing temperature is set to 150-220°C, the screw speed is 20-80rpm, and the pulling speed of the film pulling device is 10-50m/min. 4. The method for preparing a three-layer co-extruded fully biodegradable plastic film as claimed in claim 1, wherein the thickness of the three-layer co-extruded fully biodegradable plastic film is 10-15 μm. 5. the preparation method of three-layer co-extrusion full biodegradable mulch film as claimed in claim 1, is characterized in that, described PPC, PBAT, PLA are the material through drying treatment; The viscosity-average molecular weight of the PPC is 70,000-180,000; The number average molecular weight of the PBAT is 55,000-200,000; The content of L configuration in the PLA is greater than 88%, the optical purity of the PLA is 95%, and the viscosity-average molecular weight of the PLA is 50,000-700,000. 6. The preparation method of three-layer co-extruded fully biodegradable mulch film as claimed in claim 1, is characterized in that, the order number of described inorganic filler ≥ 3000 orders, and described inorganic filler is talcum powder, silicon dioxide, nitrided at least one of boron; The plasticizer is at least one of polyethylene glycol and acetyl tri-n-butyl citrate, wherein the molecular weight of polyethylene glycol is 200-2000g/mol; The crosslinking agent is at least one of diphenylmethane diisocyanate, toluene-2,4-diisocyanate, ADR-4380, ADR-4370, and ADR-4300; The light stabilizer is one or both of UV234, UV326, UV-P, UV371, SORB2020, and its molecular weight is between 300-4000g/mol; The antioxidant is one or both of antioxidant 1010, antioxidant 168, antioxidant 1076, antioxidant DLTP, and antioxidant 126; Described lubricant is pentaerythritol stearate. 7. A three-layer co-extrusion fully biodegradable mulch film, characterized in that it is made by a three-layer co-extrusion blow molding process, including a middle layer, and an inner layer and an outer layer respectively positioned on both sides of the middle layer; The outer layer includes the following raw material components: 80-95wt% of PBAT, 2-10wt% of plasticizer, 0.5-3wt% of crosslinking agent, 0.5-2wt% of antioxidant, 0.5-1.5wt% of lubricant, light Stabilizer 0.5-2wt%; The intermediate layer includes the following raw material components: PPC 60-90wt%, PBAT 10-40wt%, plasticizer 2-10wt%, crosslinking agent 0.5-3wt%, antioxidant 0.5-2wt%, lubricant 0.5 -1.5wt%, light stabilizer 0.5-2wt%; The inner layer includes the following raw material components: PLA 10-40wt%, PBAT 50-80wt%, inorganic filler 2-15wt%, plasticizer 2-10wt%, crosslinking agent 0.5-3wt%, antioxidant 0.5 -2wt%, lubricant 0.5-1.5wt%, light stabilizer 0.5-2wt%. 8. The three-layer co-extrusion fully biodegradable mulch film as claimed in claim 7, is characterized in that, in the three-layer co-extrusion blow molding process, the three extruders respectively corresponding to the outer layer, the middle layer, and the inner layer The material extrusion speed is 0.8-1.2:0.8-1.2:1, and the thickness of the three-layer co-extruded fully biodegradable plastic film is 10-15 μm. 9. The three-layer co-extruded fully biodegradable mulch film according to claim 7, wherein the PPC, PBAT, and PLA are all dried materials; The viscosity-average molecular weight of the PPC is 70,000-180,000; The number average molecular weight of the PBAT is 55,000-200,000; The content of L configuration in the PLA is greater than 88%, the optical purity of the PLA is 95%, and the viscosity-average molecular weight of the PLA is 50,000-700,000. 10. The three-layer co-extrusion fully biodegradable mulch film as claimed in claim 7, wherein the mesh number of the inorganic filler is more than or equal to 3000 mesh, and the inorganic filler is talcum powder, silicon dioxide, boron nitride at least one; The plasticizer is at least one of polyethylene glycol and acetyl tri-n-butyl citrate, wherein the molecular weight of polyethylene glycol is 200-2000g/mol; The crosslinking agent is at least one of diphenylmethane diisocyanate, toluene-2,4-diisocyanate, ADR-4380, ADR-4370, and ADR-4300; The light stabilizer is one or both of UV234, UV326, UV-P, UV371, SORB2020, and its molecular weight is between 300-4000g/mol; The antioxidant is one or both of antioxidant 1010, antioxidant 168, antioxidant 1076, antioxidant DLTP, and antioxidant 126; Described lubricant is pentaerythritol stearate.