Full-biodegradable mulching film and preparation method thereof

Abstract

The full-biodegradable mulching film is prepared from the following components in parts by weight: 80 to 95 parts of poly (butylene adipate), 3 to 10 parts of polypropylene carbonate, 0.1 to 1 part of nano chitosan, 0.2 to 5 parts of a compatilizer, 0.1 to 1 part of a slipping agent, 0.1 to 0.6 part of an ultraviolet light absorber, 0.1 to 0.6 part of an antioxidant and 0.1 to 0.6 part of a light stabilizer. According to the invention, a small amount of nano chitosan is added into the degradable material, so that the mechanical property of the degradable material can be improved, no influence is caused to soil, and full biodegradation is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of fully biodegradable mulch films, and in particular relates to a fully biodegradable mulch film and a preparation method thereof. Background Art

[0002] By covering the soil surface, mulch can effectively regulate soil temperature, maintain soil moisture, reduce water evaporation, and effectively inhibit the growth of weeds, thereby providing a more favorable growth environment for crops. With the deepening of the concept of sustainable agricultural development, the research and application of biodegradable mulch has gradually received attention. Fully biodegradable mulch can naturally degrade into water and carbon dioxide in the soil without causing environmental pollution. Compared with traditional mulch, the use of fully biodegradable mulch can increase soil temperature, maintain soil moisture, and thus promote crop growth, increase yield and quality. With the continuous improvement of environmental awareness and the promotion of policies, fully biodegradable mulch will gradually replace traditional mulch and become the mainstream choice for future agricultural production. The promotion and use of fully biodegradable mulch will help reduce agricultural pollution, protect the ecological environment, and promote sustainable agricultural development.

[0003] PBAT (polybutylene adipate) is a bio-based and degradable polyester material made from monomers such as adipic acid and butanediol through polymerization. PBAT has excellent flexibility and heat resistance. Compared with traditional plastics, PBAT can degrade faster under natural conditions after use, reducing long-term pollution to the environment. PBAT has similar tensile and ductility to LDPE, in which the butylene terephthalate (BT) chain provides rigidity to the material, while the butylene adipate (BA) chain provides flexibility, so PBAT can be used as a film material. Summary of the invention

[0004] In order to solve the deficiencies of the prior art, the purpose of the present invention is to provide a fully biodegradable mulch film and a preparation method thereof. By adding a small amount of nano-chitosan to the degradable material, the mechanical properties of the degradable material can be improved without affecting the soil, thereby achieving full biodegradation.

[0005] In order to achieve the above object, the present invention adopts the following technical solution: A fully biodegradable mulch film comprises the following components in parts by weight: 80-95 parts of polybutylene adipate, 3-10 parts of polypropylene carbonate, 0.1-1 part of nano-chitosan, 0.2-5 parts of a compatibilizer, 0.1-1 part of a lubricant, 0.1-0.6 parts of an ultraviolet absorber, 0.1-0.6 parts of an antioxidant and 0.1-0.6 parts of a light stabilizer.

[0006] Preferably, the melting temperature of the polybutylene adipate is 110-130° C., and the flow rate of the melt is 2-7 g / 10 min at 190° C. and 2.16 kg.

[0007] Preferably, the molecular weight of the polypropylene carbonate is 50,000-100,000.

[0008] Preferably, the particle size of the nano-chitosan is 1-5 μm.

[0009] Preferably, the compatibilizer is one or more of calcium stearate, polyvinyl alcohol, glycerol, and white oil.

[0010] Preferably, the aforementioned lubricant is erucamide and / or oleamide.

[0011] Preferably, the aforementioned ultraviolet absorber is one or more of salicylates, benzophenones, and benzotriazoles.

[0012] Preferably, the aforementioned antioxidant is one or more of antioxidant 1010, antioxidant 168, antioxidant 264, antioxidant 1076, antioxidant B215, and antioxidant B225.

[0013] Preferably, the aforementioned light stabilizer is one or more of light stabilizer 770, light stabilizer 944, light stabilizer 622, light stabilizer 2002, light stabilizer 783, and light stabilizer 2020.

[0014] A method for preparing a fully biodegradable mulch film comprises the following steps: S1. Raw material pretreatment and blending: First, polybutylene adipate (PBAT), polypropylene carbonate (PPC) and nano-chitosan were placed in a dehumidification dryer at a temperature of 70 °C and dried for 4 h for dehumidification and drying pretreatment, and then the following materials were weighed according to weight ratio: PBAT, PPC, nano-chitosan, compatibilizer, lubricant, ultraviolet absorber, antioxidant, light stabilizer, added into a high-speed mixer and blended to obtain a blend; S2. Extrusion granulation of blended raw materials: The blend obtained in step S1 is added to a twin-screw extruder for extrusion and granulation, the temperature range of the extruder is set to 140-180°C, the speed of the extruder is 100-300 rpm, and the feeding rate of the extruder is 15-30 kg / h to obtain composite modified pellets, which are dried in a dehumidifying dryer at a temperature of 70°C for 4 h for dehumidification and drying; S3. Film blowing of composite modified granules: The composite modified pellets dried in step S2 are fed into the feed port of a film blowing machine, the screw temperature is 130-180°C, the die processing temperature is 140-180°C, the film blowing thickness is 7-15 μm, and a fully biodegradable mulch film is obtained.

[0015] The benefits of the present invention are as follows: by adding a small amount of nano-chitosan to the degradable material, the mechanical properties of the degradable material can be improved, and a biodegradable material with low cost, high mechanical properties and abundant natural raw materials is obtained, and no impact is caused on the soil, and full biodegradation is achieved. The preparation process is simple, and industrial production is easy, and the invention has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of nano-chitosan enhanced PBAT of the present invention. DETAILED DESCRIPTION Embodiment 1:

[0017] A fully biodegradable mulch film comprises the following components in parts by weight: 94.5 parts of PBAT, 5 parts of PPC, 0.5 parts of nano-chitosan, 0.3 parts of polyvinyl alcohol, 0.2 parts of erucic acid amide, 0.3 parts of benzophenone ultraviolet absorber UV-531, 0.4 parts of antioxidant 1010 (primary antioxidant), 0.4 parts of antioxidant 168 (secondary antioxidant), and 0.3 parts of light stabilizer 944.

[0018] The preparation method of the fully biodegradable mulch film comprises the following steps: S1. Raw material pretreatment and blending: First, polybutylene adipate (PBAT), polypropylene carbonate (PPC) and nano-chitosan were placed in a dehumidification dryer at a temperature of 70 °C and dried for 4 h for dehumidification and drying pretreatment. Then, the following materials were weighed according to weight ratio: PBAT, PPC, nano-chitosan, polyvinyl alcohol, erucic acid amide, benzophenone ultraviolet absorber UV-531, antioxidant 1010, antioxidant 168, light stabilizer 944, added into a high-speed mixer and blended to obtain a blend; S2. Extrusion granulation of blended raw materials: The blend obtained in step S1 is added to a twin-screw extruder for extrusion and granulation, the temperature range of the extruder is set to 140-180 °C, the speed of the extruder is 200 rpm, and the feeding rate of the extruder is 20 kg / h to obtain a composite modified pellet, which is dried in a dehumidifying dryer at a temperature of 70 °C for 4 h for dehumidification and drying; S3. Film blowing of composite modified granules: The composite modified pellets dried in step S2 are fed into the feed port of a film blowing machine, the screw temperature is 130-180°C, the die processing temperature is 140-180°C, the film blowing thickness is 10 μm, and a fully biodegradable mulch film is obtained.

[0019] Embodiment 2:

[0020] A fully biodegradable mulch film comprises the following components in parts by weight: 89.5 parts of PBAT, 10 parts of PPC, 0.5 parts of nano-chitosan, 0.5 parts of polyvinyl alcohol, 0.2 parts of erucamide, 0.3 parts of UV-531, 0.4 parts of antioxidant 1010 (primary antioxidant), 0.4 parts of antioxidant 168 (secondary antioxidant), and 0.3 parts of light stabilizer 944.

[0021] The preparation method of the fully biodegradable mulch film is the same as that in Example 1.

[0022] Embodiment 3:

[0023] A fully biodegradable mulch film comprises the following components in parts by weight: 89 parts of PBAT, 10 parts of PPC, 1 part of nano-chitosan, 0.5 parts of polyvinyl alcohol, 0.2 parts of erucamide, 0.3 parts of UV-531, 0.4 parts of antioxidant 1010 (primary antioxidant), 0.4 parts of antioxidant 168 (secondary antioxidant), and 0.3 parts of light stabilizer 944.

[0024] The preparation method of the fully biodegradable mulch film is the same as that in Example 1.

[0025] Comparative Example 1: A fully biodegradable mulch film comprises the following components in parts by weight: 95 parts of PBAT, 5 parts of PPC, 0.3 parts of polyvinyl alcohol, 0.2 parts of erucamide, 0.3 parts of UV-531, 0.4 parts of antioxidant 1010 (primary antioxidant), 0.4 parts of antioxidant 168 (secondary antioxidant), and 0.3 parts of light stabilizer 944.

[0026] The preparation method of the fully biodegradable mulch film is the same as that in Example 1.

[0027] Comparative Example 2: A fully biodegradable mulch film is composed of the following raw materials in parts by weight: 99.5 parts of PBAT, 0.5 parts of nano-chitosan, 0.3 parts of polyvinyl alcohol, 0.2 parts of erucic acid amide, 0.3 parts of UV-531, 0.4 parts of antioxidant 1010 (primary antioxidant), 0.4 parts of antioxidant 168 (secondary antioxidant), and 0.3 parts of light stabilizer 944.

[0028] The preparation method of the fully biodegradable mulch film is the same as that of Comparative Example 1.

[0029] Performance testing: According to GB / T35795-2017, the tensile strength and elongation at break of the fully biodegradable mulch films prepared in Examples 1 to 3, Comparative Example 1 and Comparative Example 2 were tested. The test results are shown in Table 1.

[0030] Table 1 Performance test of fully biodegradable mulch film

[0031] It can be seen from the performance test results in Table 1 that the present invention greatly improves the tensile strength of the mulch film by adding a small amount of nano-chitosan, but has little effect on the elongation at break, while the added PPC has a greater effect on the elongation at break of the mulch film, and nano-chitosan is a degradable material and will not affect the soil, achieving full biodegradation.

Claims

1. A fully biodegradable mulch film, characterized in that: The invention comprises the following components in parts by weight: 80-95 parts of polybutylene adipate, 3-10 parts of polypropylene carbonate, 0.1-1 part of nano-chitosan, 0.2-5 parts of a compatibilizer, 0.1-1 part of a lubricant, 0.1-0.6 parts of an ultraviolet absorber, 0.1-0.6 parts of an antioxidant and 0.1-0.6 parts of a light stabilizer.

2. A fully biodegradable mulch film according to claim 1, characterized in that: The melting temperature of the polybutylene adipate is 110-130° C., and the flow rate of the melt is 2-7 g / 10 min at 190° C. and 2.16 kg.

3. A fully biodegradable mulch film according to claim 1, characterized in that: The molecular weight of the polypropylene carbonate is 50,000-100,000.

4. A fully biodegradable mulch film according to claim 1, characterized in that: The particle size of the nano-chitosan is 1-5 μm.

5. The fully biodegradable mulch film according to claim 1, characterized in that: The compatibilizer is one or more of calcium stearate, polyvinyl alcohol, glycerin and white oil.

6. A fully biodegradable ground film according to claim 1, characterized in that: The lubricant is erucamide and / or oleamide.

7. The fully biodegradable mulch film according to claim 1, characterized in that: The ultraviolet absorber is one or more of salicylates, benzophenones and benzotriazoles.

8. The fully biodegradable mulch film according to claim 1, characterized in that: The antioxidant is one or more of antioxidant 1010, antioxidant 168, antioxidant 264, antioxidant 1076, antioxidant B215, and antioxidant B225.

9. The fully biodegradable mulch film according to claim 1, characterized in that: The light stabilizer is one or more of light stabilizer 770, light stabilizer 944, light stabilizer 622, light stabilizer 2002, light stabilizer 783, and light stabilizer 2020.

10. A method for preparing a fully biodegradable mulch film according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1, drying and pre-treating the raw materials and blending them to obtain a blend; S2, extruding and granulating the blend, and drying to obtain composite modified pellets; S3, subjecting the composite modified pellets to film blowing treatment to obtain a fully biodegradable ground film.

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