Production method of cassava starch filled PBAT biodegradable mulching film

Abstract

The invention belongs to the technical field of degradable mulching films, and discloses a production method of a cassava starch filled PBAT biodegradable mulching film, the product is good in thickness and mechanical property, the main component is poly (adipic acid / butylene terephthalate) with complete degradation characteristic, the mulching film does not contain olefin raw materials such as polyethylene, a proper proportion of cassava starch and the like are added, and the biodegradable mulching film is prepared. The effective service life is more than 60 days, the film with biodegradability has no secondary pollution in the degradation process, inhibits the growth of weeds, reduces the growth water consumption and the like, also has the characteristics of yield increase, quality improvement, environmental friendliness and no need of recovery after use, can effectively preserve heat, preserve soil moisture, replace herbicides to inhibit weeds, and can effectively improve the weed resistance through the effects of microorganisms, light and temperature in soil after use. The silver gray fluorescent insect repelling powder is added, so that not only is the effect of a common mulching film achieved, but also pests can be effectively repelled, and the light-shading and anti-oxidation plasticizer has light-shading and anti-oxidation effects and also has a certain plasticizing effect.

Description

Technical Field

[0001] The invention belongs to the technical field of degradable films, and in particular to a method for producing a cassava starch-filled PBAT biodegradable mulch film. Background Art

[0002] At present, the main component of the "degradable" mulch on the market (mainly including photodegradable mulch, thermal oxygen degradable mulch, starch-filled mulch, etc.) is still polyethylene. After use, it is broken into pieces and buried in the soil and cannot be recycled at all, causing serious secondary pollution. However, due to different planting methods in different places, the mechanized recycling equipment for waste agricultural films varies greatly and has poor regional applicability, so the cost of configuring recycling machinery is very high. After mechanical recycling, manual secondary collection is still required, making it difficult to reduce the recycling cost. At present, the recycling of residual film is mostly done manually, which is not thorough and inefficient. In addition, the recycled mulch is mostly processed on-site and piled up on the ridges or field roads, which will not only pollute the environment again, but also cause waste of resources. Although the widespread use of agricultural film has played an important role in increasing agricultural yields and efficiency, due to the low recovery rate of residual mulch, the amount of residual film in the soil has gradually increased, which is very easy to cause mulch pollution; at the same time, traditional mulch cannot be degraded, and the residual mulch in the natural state can remain in the soil for more than 200 years, which has brought a series of hazards to agricultural production and the environment, so it is called "white pollution" of farmland. People are in urgent need of a production method for cassava starch-filled PBAT biodegradable mulch to meet existing usage needs and performance requirements. Summary of the invention

[0003] In view of the above problems, the present invention aims to provide a method for producing a high-temperature and high-humidity easily fully biodegradable plastic film.

[0004] The present invention is achieved through the following technical solutions: A method for producing a cassava starch-filled PBAT biodegradable mulch film comprises the following steps: (1) Preparation of maleic acid esterified starch: 80-90 parts of nadic anhydride or methyl nadic anhydride were weighed and added to 100 parts of cassava starch and then limestone powder, and the mixture was uniformly mixed in a high-speed mixer at a speed of 800-1000 rpm for 1-2 h, and filtered through a 500-mesh sieve to obtain activated cassava starch; (2) According to the weight fraction, 45-50 parts of activated cassava starch, 45-50 parts of PBAT, 0.2-0.3 parts of dispersant and 0.1-0.2 parts of lubricant are mixed evenly in a high-speed mixer, and then sent into a screw extruder for plasticization and granulation. The extruder temperature is set to 120°C for zone 1, 135°C for zone 2, 140°C for zone 3, 135°C for zone 4 and 135°C for zone 5, and the cooling temperature is 60°C. An AB twin-screw film blowing machine is used for film blowing at 150-170°C to obtain the product.

[0005] Furthermore, in step (1), the mass ratio of cassava starch to limestone powder is 19-21:1.

[0006] Furthermore, the dispersant in step (2) is palmitamide.

[0007] Furthermore, in step (2), the lubricant is palm oil.

[0008] Furthermore, the density of the PBAT in step (2) is 1.24-1.27 g / cm3, the melt index is 2-4 g / 10 min at 190°C, the melting point is not less than 115°C, and the weight average molecular weight is 50,000-80,000.

[0009] Furthermore, the cassava starch has an ash content of ≤0.2g / 100g and a fineness of 800-1000 mesh.

[0010] Furthermore, the side feed of the A screw film blowing machine is added with silver-grey fluorescent insect repellent powder, and the amount of the silver-grey fluorescent insect repellent powder added is 4-6% of the mass proportion of the main feed of the screw film blowing machine.

[0011] The silver-grey fluorescent insect repellent powder not only has the effect of ordinary mulch, but can also effectively repel pests.

[0012] Furthermore, a light-shielding antioxidant plasticizer is added to the side feed of the B screw film blowing machine, and the amount of the light-shielding antioxidant plasticizer added is 6-8% of the mass proportion of the main feed of the screw film blowing machine, preferably triphenyl phosphite or tricresyl phosphate, which has a light-shielding and antioxidant effect, and also has a certain plasticizing effect.

[0013] Beneficial effects of the present invention: The product disclosed in the present invention is a method for producing a cassava starch-filled PBAT biodegradable mulch film. The product's thickness, mechanical properties and other indicators meet the requirements of fully biodegradable agricultural ground covering films. The main components are biomass materials such as aliphatic polyesters and aliphatic-aromatic copolyesters with complete degradation characteristics, and do not contain olefin raw materials such as polyethylene. A proper proportion of cassava starch is added, and the effective service life is more than 60 days. The film has biodegradable properties, and there is no secondary pollution during the degradation process. It inhibits the growth of weeds and reduces water consumption for growth. It also has the characteristics of increasing production and improving quality, being environmentally friendly, and not requiring recycling after use. It can effectively keep warm and retain moisture, and can replace herbicides to inhibit weeds. After use, it is finally decomposed into carbon dioxide and water through the action of microorganisms, light and temperature in the soil. DETAILED DESCRIPTION

[0014] The present invention is described below with specific examples, but is not intended to be limiting of the present invention. Example 1

[0015] Zhongqing Fengtai Biochemical Technology's superior FOF-701 cassava starch; Zhicheng High-tech Materials' 6501 palmitamide, Foshan Weida Grain and Oil's palm oil. PBAT has a melt index of 4g / 10min at 190°C and a weight-average molecular weight of 50,000. Cassava starch has an ash content of ≤0.2g / 100g and a fineness of 800 mesh; 400-mesh Xiangcai Chemical's XC360-H silver-gray fluorescent insect repellent powder; Meilian Changhe Chemical's triphenyl phosphite.

[0016] The production method of cassava starch filled PBAT biodegradable mulch film comprises the following steps: (1) Preparation of maleic acid esterified starch: 80 parts of nadic anhydride were weighed and added to 100 parts of cassava starch and then limestone powder, the mass ratio of cassava starch to limestone powder was 19:1, and the mixture was mixed and reacted in a high-speed mixer at a speed of 800 rpm for 1 h, and filtered through a 500-mesh sieve to obtain activated cassava starch; (2) 45 parts of activated cassava starch, 45 parts of PBAT, 0.2 parts of dispersant and 0.1 parts of lubricant were mixed and mixed in a high-speed mixer according to weight fraction, and then put into a screw extruder for plasticization and granulation. The temperature is set to 120°C for zone 1, 135°C for zone 2, 140°C for zone 3, 135°C for zone 4, and 135°C for zone 5, and the cooling temperature is 60°C. An AB twin-screw film blowing machine is used for film blowing at 150°C to obtain the product, wherein the side feed of the A screw film blowing machine is added with silver-gray fluorescent insect repellent powder, and the addition amount of the above-mentioned XC360-H silver-gray fluorescent insect repellent powder is 4% of the mass proportion of the main feed of the screw film blowing machine. The side feed of the B screw film blowing machine is added with a light-shielding antioxidant plasticizer, and the addition amount of the light-shielding antioxidant plasticizer is 6% of the mass proportion of the main feed of the screw film blowing machine. Example 2

[0017] Wengjiang Starch Premium Cassava Starch; Wengjiang Reagent Palmitamide, Maoming Yixiangyuan Palm Oil. PBAT has a melt index of 2g / 10min at 190°C and a weight average molecular weight of 80,000. Cassava starch ash content ≤0.2g / 100g, 1000 mesh; Foshan Xiucai Chemical 300 mesh silver-grey fluorescent insect repellent powder; Weifang Wansheng Tritolyl Phosphate.

[0018] The production method of cassava starch filled PBAT biodegradable mulch film comprises the following steps: (1) Preparation of maleic acid-esterified starch: 90 parts of methyl nadic anhydride were weighed and added to 100 parts of cassava starch and then limestone powder, the mass ratio of cassava starch to limestone powder was 21:1, and the mixture was mixed and reacted in a high-speed mixer at a speed of 1000 rpm for 2 h, and filtered through a 500-mesh sieve to obtain activated cassava starch; (2) 50 parts of activated cassava starch, 50 parts of PBAT, 0.3 parts of dispersant and 0.2 parts of lubricant were mixed and mixed in a high-speed mixer according to weight fraction, and then put into a screw extruder for plasticization. The extruder temperature is set to 120°C in zone 1, 135°C in zone 2, 140°C in zone 3, 135°C in zone 4, 135°C in zone 5, and the cooling temperature is 60°C. An AB twin-screw film blowing machine is used for film blowing at 170°C to obtain the product, wherein the side feed of the A screw film blowing machine is added with silver-grey fluorescent insect repellent powder, and the addition amount of the silver-grey fluorescent insect repellent powder is 6% of the mass proportion of the main feed of the screw film blowing machine; wherein the side feed of the B screw film blowing machine is added with a light-shielding antioxidant plasticizer, and the addition amount of the light-shielding antioxidant plasticizer is 8% of the mass proportion of the main feed of the screw film blowing machine.

[0019]

[0020] Note: Melting point is carried out in accordance with GB / T19466.3-2004. Heating rate is 10℃ / min. Melt mass flow rate (MFR) is carried out in accordance with method A in GB / T3682-2000. The test is carried out under the standard environment specified in GB / T2918-1998, with an ambient temperature of 23℃ and a relative humidity of 50%. The test conditions are D (temperature: 190℃, load: 2.16kg). The sample is dried particles with a mass of 8g to 10g. The carboxyl content test is carried out in accordance with method A in GB / T14190-2008. The mixed solvent is phenol-chloroform with a volume ratio of 2:3. The standard titration solution is potassium hydroxide-benzyl alcohol with a concentration of 0.01mol / l, prepared and calibrated with reference to 4.24 in GB / T601-2002. The concentration of bromophenol blue indicator is 0.2%. Sample preparation: 0.5g sample is dissolved in 25.00ml phenol-chloroform mixed solvent. The moisture content test is carried out according to the B method specified in GB / T12006.2-2009. The recommended sample size is 0.5g. The temperature of the heating device is 80℃. The color value test is carried out according to 5.5.2 of GB / T14190-2008. The tensile test (tensile strength at break, tensile strain at break) samples are prepared according to the A-type mold in GB / T17037.1-1997. The state adjustment of the sample is carried out according to the provisions of GB / T2918-1998, and the state adjustment conditions are 23℃ and 40h. The test should be carried out under the standard environment specified in GB / T2918-1998, with an environmental temperature of 23℃ and a relative humidity of 50%±10%. The test is carried out according to the provisions of GB / T1040.2-2006. The test speed is 50mm / min. The bending test (bending strength, bending modulus) specimen is an 80mm×10mm×4mm long injection molding specimen prepared according to GB / T17037.1-1997. The state adjustment of the specimen is carried out according to the provisions of GB / T2918-1998, and the state adjustment conditions are 23℃±2℃ and 40h. The test should be carried out under the standard environment specified in GB / T2918-1998, with an environmental temperature of 23℃ and a relative humidity of 50%±10%. The test is carried out according to GB / T9341-2008, and the test speed is 2mm / min. The cantilever beam notched impact strength specimen is an 80mm×10mm×4mm long injection molding specimen prepared according to GB / T17037.1-1997. The specimen should be processed into an A-type notch within 1h after injection molding. The state adjustment of the sample shall be carried out in accordance with the provisions of GB / T2918-1998, and the state adjustment conditions are 23℃±2℃ and 40h. The test shall be carried out in the standard environment specified in GB / T2918-1998, with the temperature of the environment being 23℃ and the relative humidity being 50%±10%. The test shall be carried out in accordance with the provisions of GB / T1843-2008.The load deformation temperature specimen is an 80mm×10mm×4mm long injection molding specimen prepared according to GB / T17037.1-1997. The state adjustment of the specimen is carried out according to the provisions of GB / T2918-1998, and the state adjustment conditions are a temperature of 23°C and an adjustment time of 40h. The test should be carried out under the standard environment specified in GB / T2918-1998, with an ambient temperature of 23°C and a relative humidity of 50%. The test is carried out according to the B method specified in GB / T1634.2-2004. During the test, the starting temperature of the heating device should be lower than 27°C. The heating rate is 120°C / h. The ash test is carried out according to GB / T9345.1-2008, using the direct combustion method (A method) with a burning temperature of 850°C. The biodegradability rate is carried out according to GB / T19277.1-2011; refer to GB / T35795-2017 fully biodegradable agricultural ground covering film.

Claims

1. A method for producing cassava starch-filled PBAT biodegradable mulch film, characterized in that: The following steps are involved: (1) Preparation of maleic acid esterified starch: 80-90 parts of nadic anhydride or methyl nadic anhydride were weighed and added to 100 parts of cassava starch and then limestone powder, and the mixture was uniformly mixed in a high-speed mixer at a speed of 800-1000 rpm for 1-2 h, and filtered through a 500-mesh sieve to obtain activated cassava starch; (2) According to the weight fraction, 45-50 parts of activated cassava starch, 45-50 parts of PBAT, 0.2-0.3 parts of dispersant and 0.1-0.2 parts of lubricant are mixed evenly in a high-speed mixer, and then sent into a screw extruder for plasticization and granulation. The extruder temperature is set to 120°C for zone 1, 135°C for zone 2, 140°C for zone 3, 135°C for zone 4 and 135°C for zone 5, and the cooling temperature is 60°C. An AB twin-screw film blowing machine is used for film blowing at 150-170°C to obtain the product.

2. The method for producing cassava starch-filled PBAT biodegradable mulch film according to claim 1, characterized in that: In the step (1), the mass ratio of cassava starch to limestone powder is 19-21:

1.

3. The method for producing cassava starch-filled PBAT biodegradable mulch film according to claim 1, characterized in that: The dispersant in step (2) is palmitamide.

4. The method for producing cassava starch-filled PBAT biodegradable mulch film according to claim 1, characterized in that: The lubricant in step (2) is palm oil.

5. The method for producing cassava starch-filled PBAT biodegradable mulch film according to claim 1, characterized in that: The PBAT in step (2) has a melt index of 2-4 g / 10 min at 190° C., a melting point of not less than 115° C., and a weight average molecular weight of 50,000-80,000.

6. The method for producing cassava starch-filled PBAT biodegradable mulch film according to claim 1, characterized in that: The cassava starch has an ash content of ≤0.2g / 100g and a fineness of 800-1000 meshes.

7. The method for producing cassava starch-filled PBAT biodegradable mulch film according to claim 1, characterized in that: The side feed of the A screw film blowing machine is added with silver-grey fluorescent insect repellent powder, and the addition amount of the silver-grey fluorescent insect repellent powder is 4-6% of the mass proportion of the main feed of the screw film blowing machine.

8. The method for producing cassava starch-filled PBAT biodegradable mulch film according to claim 1, characterized in that: The side feed of the B screw film blowing machine is added with a light-shielding antioxidant plasticizer, and the added amount of the light-shielding antioxidant plasticizer is 6-8% of the mass proportion of the main feed of the screw film blowing machine.

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