A fully biodegradable PE mulch film with specific spectral absorption characteristics and a preparation method thereof

Abstract

The present application relates to the field of agricultural mulch films, and specifically discloses a fully biodegradable PE mulch film with specific spectral absorption characteristics and a preparation method thereof. A fully biodegradable PE mulch film with specific spectral absorption characteristics comprises a base layer and a color layer located on at least one side of the base layer and provided with at least one layer; the base layer comprises raw materials: PE resin, biodegradable masterbatch and filler; the color layer comprises raw materials: biodegradable masterbatch, spectrum-adjusting pigment masterbatch, plant fiber, antioxidant, light stabilizer, dehumidifier; the spectrum-adjusting pigment masterbatch comprises raw materials: 100 parts of PE resin, 14-20 parts of pigment powder, 1-3 parts of dispersant, 7-14 parts of needle-shaped filler and 5-10 parts of chitosan porous microspheres. The PE mulch film of the present application has specific spectral absorption characteristics, which can meet the requirements of maximizing the photosynthetic efficiency of different crops. At the same time, while meeting the basic performance of the PE mulch film, it can be rapidly degraded naturally to reduce the pollution of residual film in farmland.

Description

Technical Field

[0001] The present application relates to the technical field of agricultural mulch films, and more specifically, to a fully biodegradable PE mulch film having specific spectral absorption characteristics and a preparation method thereof. Background Art

[0002] Agricultural mulch is ground covering film, which has become one of the important materials for agricultural production in my country. Mulch covering is an agricultural cultivation technology that has the functions of heat preservation, entropy increase, disease prevention, insect resistance and weed suppression. At present, mulch is mostly made of plastics such as polyethylene or polyvinyl chloride. Due to its high stability, it degrades very slowly in nature, and it cannot be decomposed by microorganisms or absorbed by crops, causing great harm to the soil. In addition, various types of agricultural mulch on the market can be customized according to the needs of different crops, but they fail to fully integrate the two advantages of environmental degradation and efficient spectrum utilization.

[0003] The prior art provides agricultural mulch films in various colors, such as black, silver-gray, green, blue, etc. For example, the Chinese invention patent document with application number CN2016100487793 discloses a black liquid mulch film composed of the following substances in parts by mass: 80-120 parts of asphalt, 20-40 parts of seaweed concentrate, 3-5 parts of polyvinyl alcohol, 3-5 parts of carboxymethyl cellulose, 3-5 parts of silk protein powder, 3-5 parts of oxygenator, 1-2 parts of herbicide particles, 1-3 parts of alkyl diamine, 1-3 parts of Tween, and 80-100 parts of water.

[0004] The above-mentioned black mulch can improve soil structure, is easily degraded, and has the function of weeding and promoting root growth. It is suitable for cultivating crops such as late tomatoes, autumn cucumbers and cabbage in seasons with severe weeds or high temperatures. However, the black mulch increases entropy slowly and is not as good as the transparent mulch in significantly reducing ground temperature and maintaining soil moisture. Therefore, the spectral matching for other crops, such as eggplant, melon, strawberry, etc., is not accurate enough, resulting in its potential in increasing production and improving quality not being fully realized.

[0005] With respect to the above-mentioned related technologies, the inventors found that the current mulch films cannot both meet the requirements of different crops for specific spectra and ensure the requirements of environmentally friendly degradation. Summary of the invention

[0006] In order to make the mulch film meet the specific spectrum requirements of different crops and be biodegradable, the present application provides a fully biodegradable PE mulch film with specific spectral absorption characteristics and a preparation method thereof.

[0007] In the first aspect, the present application provides a fully biodegradable PE mulch film with specific spectral absorption characteristics, using the following technical solution:

[0008] A fully biodegradable PE ground film with specific spectral absorption characteristics, comprising a base layer and a color layer located on at least one side of the base layer, wherein the color layer is provided as at least one layer;

[0009] The base layer comprises the following raw materials in parts by weight: 70-95 parts of PE resin, 1-3 parts of biodegradable masterbatch and 0-30 parts of filler;

[0010] The color layer comprises the following raw materials in parts by weight: 0.5-2 parts of biodegradable masterbatch, 0-10 parts of spectrum adjustment pigment masterbatch, 0-1 parts of plant fiber, 0-3 parts of antioxidant, 0-3 parts of light stabilizer, and 0-3 parts of dehumidifier;

[0011] The spectrum adjustment pigment masterbatch comprises the following raw materials in parts by weight: 100 parts of PE resin, 14-20 parts of pigment powder, 1-3 parts of dispersant, 7-14 parts of needle-shaped filler and 5-10 parts of chitosan porous microspheres;

[0012] The pigment powder is selected from at least one of white pigment powder, black pigment powder, red pigment powder, yellow pigment powder, blue pigment powder, green pigment powder, purple pigment powder, orange pigment powder, silver pigment powder, gray pigment powder and silver-gray pigment powder.

[0013] By adopting the above technical scheme, pigments of different colors can be adjusted and combined to obtain spectral adjustment pigments of different colors, such as ground films of red, blue, green, yellow, black, silver-gray, silver-black and other colors. Ground films of different colors selectively filter light of different wavelengths, so that the wavelength distribution of the transmitted light changes, and the color of the ground film also has an important influence on the light filtering effect, the incident angle of sunlight and the refraction of light. At the same time, ground films of different colors also have a significant effect on the light energy utilization efficiency and the uniformity of light. Therefore, by optimizing the color, design and application of the ground film, the light energy utilization efficiency and production yield of crops can be improved. Different colors of mulch films have obvious effects on crop production and development. The light transmittance of black mulch films is low, which limits the photosynthesis of crops, making the height and stem diameter of crops relatively small. Therefore, it is suitable for cultivating summer radish, cabbage, late tomatoes, etc. The light transmittance of white mulch films is high, which is conducive to the photosynthesis of crops. The height and stem diameter of plants are relatively large. There are certain differences in the spectral transmission of red mulch films, which can enhance the absorption of photosynthetically active radiation in photosynthesis, thereby promoting the growth and development of crops. It can be seen that colored mulch films can control the transmittance and wavelength of light, adjust light and temperature, prevent ultraviolet rays and excess light from damaging crops, lower room temperature, and reduce the occurrence of diseases and pests. Moreover, colored mulch films can reduce water evaporation, increase indoor relative humidity, save water resources and reduce the number of irrigation times. At the same time, colored mulch films can also regulate the growth characteristics of crops and improve the yield and quality of crops.

[0014] By selecting different spectral adjustment pigments to make PE mulch film have different colors, we can obtain mulch film with different light transmittance, so it can adapt to crops with different spectral absorption, and has the advantage of one film for multiple uses; and the base layer made of PE resin and biodegradable masterbatch can enable the PE mulch film to maintain good mechanical properties, and at the same time it can quickly degrade naturally after use, thereby reducing the pollution of residual film in farmland.

[0015] Chitosan porous microspheres are added to the spectrum-adjusting pigment masterbatch, which have a large specific surface area and void structure, can provide more microbial attachment points and degradation channels, increase the contact area between microorganisms and PE mulch, and help microorganisms to better contact the surface of PE materials. Chitosan has good biocompatibility and can provide a suitable living environment for microorganisms, thereby promoting the biodegradation process. Microorganisms will secrete specific enzymes during the attachment and growth process to attack the polymer chains of the PE film and break them into small molecules. The porous microsphere structure helps these enzymes diffuse faster into the interior of the PE material, thereby increasing the biodegradation rate.

[0016] Fillers and dispersants can increase the dispersibility of pigments and reduce the color difference on the surface of the mulch film. Needle-shaped fillers are inorganic rigid particles. When added to the pigment masterbatch, they can promote a proper increase in the viscosity of the system, increase the shearing effect of the melt, and effectively prevent the agglomeration of pigment particles, thereby improving the dispersibility of the pigment powder in the pigment masterbatch in the PE resin and achieving better coloring effects. In addition, the needle-shaped filler uses its own needle-shaped structure to act as an abrasive for the pigment powder with a larger relative surface energy and easy to agglomerate, which is beneficial to the dispersion of the pigment powder, while preventing the agglomeration of the pigment powder and improving the coloring efficiency.

[0017] Optionally, the base layer comprises the following raw materials in parts by weight: 70-80 parts of PE resin, 1-2 parts of biodegradable masterbatch and 10-20 parts of filler;

[0018] The color layer comprises the following raw materials in parts by weight: 1-1.5 parts of biodegradable masterbatch, 2-5 parts of spectrum regulating pigment masterbatch, 0.1-0.5 parts of plant fiber, 1-1.5 parts of antioxidant, 1-2 parts of light stabilizer, and 1-2 parts of dehumidifier.

[0019] Optionally, the base layer comprises the following raw materials in parts by weight: 80 parts of PE resin, 2 parts of biodegradable masterbatch and 20 parts of filler;

[0020] The color layer comprises the following raw materials in parts by weight: 1.5 parts of biodegradable masterbatch, 5 parts of spectrum regulating pigment masterbatch, 0.5 parts of plant fiber, 1.5 parts of antioxidant, 2 parts of light stabilizer, and 2 parts of dehumidifier.

[0021] Optionally, the base layer comprises the following raw materials in parts by weight: 80 parts of PE resin, 2 parts of biodegradable masterbatch and 20 parts of filler;

[0022] The color layer comprises the following raw materials in parts by weight: 1.5 parts of biodegradable masterbatch, 0.5 parts of plant fiber, 1.5 parts of antioxidant, 2 parts of light stabilizer, and 2 parts of dehumidifier.

[0023] Optionally, the pigment powder is a light silver-grey pigment powder prepared by mixing 90% white pigment powder, 4% black pigment powder and 6% silver pigment powder.

[0024] Optionally, the pigment powder is a medium silver-grey pigment powder prepared by mixing 85% white pigment powder, 5% black pigment powder and 10% silver pigment powder.

[0025] Optionally, the pigment powder is a dark silver-grey pigment powder prepared by mixing 70% white pigment powder, 15% black pigment powder and 15% silver pigment powder.

[0026] Optionally, the pigment powder is a darker silver-grey pigment powder prepared by mixing 50% white pigment powder, 25% black pigment powder and 25% silver pigment powder.

[0027] Optionally, the pigment powder is a silver-gray pigment powder with metallic luster prepared by mixing 40% white pigment powder, 40% black pigment powder, 10% gray pigment powder and 10% silver pigment powder.

[0028] Optionally, the pigment powder is a silver-black pigment powder prepared by mixing 40-50% black pigment powder and 50-60% white pigment powder.

[0029] Optionally, the dispersant comprises cellulase and fatty alcohol polyoxyethylene ether in a mass ratio of 1:4-5.

[0030] By adopting the above technical scheme, cellulase is a protein and also a biological macromolecular substance. From a structural analysis, the cellulase protein molecule has separated independent hydrophobic and hydrophilic regions, so it exhibits unique colloidal properties. The hydrophobic region is composed of non-polar amino acids such as phenylalanine, tyrosine and tryptophan, while the hydrophilic region is composed of polar amino acids such as aspartic acid, glutamic acid and histidine, so it can provide certain crystal points and steric repulsion for the dispersed pigment to make it fully stable. Fatty alcohol polyoxyethylene ether is a non-ionic surfactant, so it can complement the cellulase structure and match the molecular weight size, which can play a synergistic enhancement role in the dispersion of organic pigments, so that the pigment powder can be dispersed more evenly when preparing the pigment masterbatch, thereby making the coloring of the PE mulch more uniform.

[0031] Optionally, the pigment powder is pretreated by the following method:

[0032] Add the pigment powder to a mixture of deionized water and anhydrous ethanol, add ammonia water after ultrasonic dispersion, and stir at 25-30°C for 30-40 minutes to obtain a pigment stock solution;

[0033] Disperse tetraethyl orthosilicate in anhydrous ethanol, heat to 80-85°C and stir for 100-120 minutes, then drip into the pigment stock solution, wash with anhydrous ethanol and deionized water in sequence after complete dripping, vacuum dry, calcine at 500-550°C for 3-5 hours to obtain a coating, the mass ratio of tetraethyl orthosilicate to pigment powder is 2-2.5:1;

[0034] Disperse hexadecyl dimethyl benzyl ammonium chloride in deionized water, add the coating, mix evenly, filter and dry, and the mass ratio of hexadecyl dimethyl benzyl ammonium chloride to pigment powder is 0.02-0.04:1.

[0035] By adopting the above technical scheme, ethyl orthosilicate is partially hydrolyzed under the catalysis of ammonia water to generate primary particles of silica, and then the primary silica ions collide with the silica precipitate particles in water, overcome the nucleation barrier, grow with the nano silica precipitate particles as the crystal nucleus, and then grow into a core-shell structure, and the particles that have formed the core-shell structure in water also collide continuously, and the silica ions on the surface are cross-linked by polymerization, so that a hydrolysis condensation reaction can occur on the surface of the pigment powder to form a silica layer, and a mesoporous silica coating layer is formed after calcination, and then the surface of the coating is modified by hexadecyl dimethyl benzyl ammonium chloride. Hexadecyl dimethyl benzyl ammonium chloride is a cationic surfactant, and its molecular structure contains long-chain alkyl groups, which can be adsorbed on the surface of the coating to form a dense hydrophobic film, and hexadecyl dimethyl benzyl ammonium chloride is a cationic surfactant, which can generate positive charges on the surface of the coating layer, and the mesoporous silica layer contains silanol groups on the surface, and the solution is protonated in the aqueous solution, that is, the Si-OH group loses protons (H +), so that the surface of the mesoporous silica layer is negatively charged, so the positive charge generated by hexadecyl dimethyl benzyl ammonium chloride can produce electrostatic adsorption with the mesoporous silica layer with negative charge, and at the same time, the hydrophobic film formed by the long-chain alkyl on the surface of the mesoporous silica layer has a certain steric hindrance effect, which can prevent water molecules from contacting the mesoporous silica layer, improve its surface non-polarity, thereby increasing the dispersibility of pigment powder and PE resin, so that the coloring of the colored PE ground film surface is more uniform; in addition, the coating is treated with hexadecyl dimethyl benzyl ammonium chloride, and the cellulase protein White interacts with hexadecyl dimethyl benzyl ammonium chloride and forms a stable association structure. Hexadecyl dimethyl benzyl ammonium chloride combines with the oppositely charged groups in the protein through Coulomb force, and the hydrophobic chains in hexadecyl dimethyl benzyl ammonium chloride interact with the hydrophobic groups in the protein. The two cooperate with each other, have matching molecular weights and complementary structures, and have a synergistic dispersing effect on the pigment. Finally, the mesoporous silica coating layer, due to its porous structure and large specific surface area, can increase the attachment sites of microorganisms, continuously degrade the color layer, and further improve the biodegradation rate.

[0036] Optionally, the chitosan porous microspheres are chitosan / polyvinyl alcohol porous microspheres loaded with organic acid complexed iron.

[0037] By adopting the above technical scheme, the chitosan porous microspheres are very brittle and have poor mechanical properties, and cannot improve the mechanical properties of the PE mulch. Therefore, polyvinyl alcohol and chitosan are used to make porous microspheres. Polyvinyl alcohol is a water-soluble polyhydroxy polymer with excellent biocompatibility and non-toxicity to improve the stability and mechanical strength of the porous microspheres. Chitosan is a pH-sensitive polymer. Under acidic conditions, the amino groups on its molecular chains are protonated. Under the action of electrostatic repulsion, the chitosan molecular chains open and dissolve. After the polyvinyl alcohol solution and the chitosan solution are blended, the chitosan molecular chains and the polyvinyl alcohol molecular chains will be entangled with each other under the action of hydrogen bonds. When the mixed solution is dropped into an alkaline solution, the chitosan molecular chains are deprotonated, and the hydrophobic effect and hydrogen bonding effect will cause the chitosan molecules to curl and entangle, thereby solidifying to obtain chitosan / polyvinyl alcohol hydrogel, which is then pre-frozen and then subjected to evaporation. The hydrogen bonding between the chitosan molecular chain and the polyvinyl alcohol molecular chain is strengthened in one step, and finally freeze-dried. After the ice crystals are completely sublimated, porous microspheres with high porosity and good mechanical properties are obtained, thereby providing more attachment sites for microbial loads and increasing the biodegradation rate; organic acid complexed iron can increase the bioavailability of PE film, mainly through complexation to improve the stability and solubility of metal ions, thereby making it easier to be used by microorganisms. Complexed iron may serve as a trace element required for microbial growth, improving its activity, thereby increasing the ability of microorganisms to attack PE film. Iron ions can catalyze oxidation reactions under appropriate conditions to produce active oxygen species such as free radicals, which may cause oxidative damage to PE film and accelerate its degradation. In addition, complexed iron also interacts with functional groups on the surface of PE film to change its surface properties, making it more susceptible to microbial attack or chemical degradation.

[0038] Optionally, the biodegradable masterbatch is prepared by the following method:

[0039] The cellulose nanofibers are dispersed in a Tris-HCl buffer, stirred evenly, and dopamine hydrochloride is added, reacted at 30-35° C. for 20-24 hours, centrifuged, concentrated, and washed with water until neutral, to obtain polydopamine-modified cellulose nanofibers;

[0040] The manganese peroxidase and polydopamine-modified cellulose nanofibers are mixed, shaken at 40-45° C. for 2-3 hours, and then concentrated to obtain an intermediate;

[0041] The intermediate is mixed evenly with titanium dioxide alcohol sol and 0.2-0.3wt% octadecyltrimethylammonium chloride aqueous solution, aged and dried, and then mixed with LDPE resin, extruded and granulated to obtain biodegradable masterbatch.

[0042] By adopting the above technical scheme, the cellulose nanofibers have a higher specific surface area and can provide a large number of attachment sites for the attachment of biological enzymes. In addition, polydopamine with excellent viscosity is wrapped on the cellulose nanofibers, so that the reaction sites between the cellulose nanofibers and the manganese peroxidase are increased, which is more conducive to the immobilization of the biological enzyme. Moreover, the surface of the cellulose nanofibers is rich in groups such as catechol and quinone groups produced in the oxidation process of dopamine. These groups can react with the amino and sulfhydryl groups in the manganese peroxidase, so that the manganese peroxidase is well connected to the polydopamine-modified cellulose nanofibers to form a solidification system intermediate. The adhesion and coating effect of polydopamine not only provides a protective layer for the enzyme, reduces the direct impact of the external environment on the enzyme, and maintains the structural stability and high temperature resistance of the enzyme, but also reduces the direct impact of high temperature on the enzyme molecules and reduces the risk of enzyme inactivation. Manganese peroxidase can catalyze the production of highly oxidizing Mn 3+ ions, thereby initiating free radical oxidation reactions of PE resin, and these free radical oxidation reactions will trigger a series of free radical chain reactions, resulting in the breakage of PE resin molecular chains and promoting the degradation of PE resin. As PE resin degrades, larger PE molecules are gradually degraded into smaller molecular fragments, such as aldehydes, ketones, alcohols, acids and other small molecular compounds; finally, titanium dioxide aerogel is prepared on the intermediate by atmospheric pressure drying. Titanium dioxide aerogel has a strong heat insulation effect and can block part of the heat during hot melting to avoid the adverse effect of temperature on the activity of manganese peroxidase. Moreover, manganese peroxidase itself has a strong high temperature resistance, which slows down the effect of temperature on its activity. Octadecyltrimethylammonium chloride can make titanium dioxide aerogel hydrophobic and enhance its non-polarity, thereby enhancing its dispersibility in PE resin. Therefore, the prepared biodegradable masterbatch can further improve the dispersibility of pigment powder when it is blended with spectrally adjusted pigment masterbatch to prepare a color layer.

[0043] Optionally, the dosage of the biodegradable masterbatch raw materials is as follows: 0.4-0.5 parts by weight of cellulose nanofibers, 0.1-0.15 parts by weight of dopamine hydrochloride, 15-25 U / g of manganese peroxidase, 1-1.5 parts by weight of titanium dioxide alcohol gel, 0.2-0.5 parts by weight of octadecyltrimethylammonium chloride, and 3-5 parts of LDPE resin.

[0044] By adopting the above technical scheme, manganese peroxidase is adhered and coated on cellulose nanofibers using polydopamine, and then titanium dioxide aerogel is used to increase the high temperature resistance of manganese peroxidase. At the same time, octadecyltrimethylammonium chloride is used to improve the non-polarity of titanium dioxide aerogel and improve its dispersibility with LDPE resin.

[0045] Optionally, the thickness of the fully biodegradable PE mulch film is 7-20 μm.

[0046] By adopting the above technical solution, the ground film of the above thickness can not only provide higher impact resistance and tensile resistance, and prevent the ground film from being punctured by crops, soil or stones when covered, but also provide better light absorption effect.

[0047] Optionally, the needle-shaped filler is selected from at least one of needle-shaped alumina, needle-shaped aluminum hydroxide, needle-shaped calcium silicate and needle-shaped wollastonite.

[0048] By adopting the above technical solution, the needle-shaped filler can increase the dispersibility of the pigment powder and reduce the agglomeration of the pigment particles when mixed with the pigment powder.

[0049] Optionally, the PE resin includes HDPE, LDPE and LLDPE in a mass ratio of 1:2-2.5:2-2.5.

[0050] By adopting the above technical solutions, HDPE has high rigidity and high strength, providing excellent tensile strength and creep properties for PE mulch. LDPE has softness and good extensibility, which can increase the flexibility and impact strength of PE mulch. LLDPE combines the high strength of HDPE and the toughness of LDPE, which can make PE mulch have better tear strength and puncture resistance.

[0051] Optionally, the filler is selected from at least one of calcium carbonate, secondary recycled PE mulch and plastic waste;

[0052] The plant fiber is selected from at least one of bamboo fiber, wheat straw fiber and hemp fiber;

[0053] The antioxidant is selected from at least one of antioxidant 1010, antioxidant 168, antioxidant 1076, and antioxidant 330;

[0054] The light stabilizer is selected from at least one of o-hydroxybenzophenone, benzotriazole, phenyl salicylate, zinc oxide and titanium dioxide;

[0055] The dehumidifier is selected from at least one of anhydrous calcium chloride, diatomaceous earth, silica gel, activated carbon, 4A molecular sieve activation powder and 3A molecular sieve activation powder.

[0056] In a second aspect, the present application provides a method for preparing a fully biodegradable PE mulch film having specific spectral absorption characteristics, using the following technical solution:

[0057] A method for preparing a fully biodegradable PE mulch film with specific spectral absorption characteristics comprises the following steps:

[0058] The PE resin and the biodegradable masterbatch are mixed evenly, and extruded into granules to obtain the base layer raw material;

[0059] The biodegradable masterbatch, the spectrum regulating pigment masterbatch, the plant fiber, the antioxidant, the light stabilizer and the dehumidifier are uniformly mixed, and then extruded into granules to obtain the color layer raw material;

[0060] The base material and the color layer material are co-extruded and blow-molded to obtain a PE ground film of the base layer and the color layer, wherein the pigment layer is located on at least one side of the base layer, and at least one color layer is provided.

[0061] By adopting the above technical scheme, after the base layer raw materials and the color layer raw materials are blended and granulated, the obtained base layer raw materials and color layer raw materials are co-extruded and blow-molded according to the structural design of the color layer and the base layer in the PE ground film. The preparation method is relatively simple and easy to realize industrial production.

[0062] In summary, this application has the following beneficial effects:

[0063] 1. Since the present application adopts a base layer containing PE resin and biodegradable masterbatch, and a color layer arranged on at least one side of the base layer, the color layer is set to at least one layer, and the color layer contains spectrum-adjusting pigment masterbatch, biodegradable masterbatch, plant fiber, etc. The spectrum-adjusting pigment masterbatch contains chitosan porous microspheres, needle-shaped fillers, dispersants and pigment powders, etc. The pigment powder can provide different colors for the spectrum-adjusting pigment masterbatch. Therefore, the PE mulch film can be adjusted according to the crop's absorption or reflection of light of a specific wavelength to adjust the color of the mulch film, thereby meeting the maximization of photosynthetic efficiency of different crops. At the same time, while maintaining basic performance, the PE mulch film meets the goal of rapid natural degradation, can reduce the pollution of residual film in farmland, and is more environmentally friendly. In addition, according to the needs of the use of the mulch film, multiple color layers can be arranged on one or both sides of the base layer to enhance its physical strength without affecting its spectral absorption and reflection characteristics.

[0064] 2. In the present application, it is preferred to use ethyl orthosilicate, hexadecyl dimethyl benzyl ammonium chloride, etc. to pretreat the pigment powder, which can improve the dispersibility of the pigment powder in the PE resin. At the same time, hexadecyl dimethyl benzyl ammonium chloride can produce a coordinated effect with the cellulase in the dispersant, increase the compatibility of the pigment and the PE resin, and improve the color uniformity of the PE mulch. In addition, the porous structure of mesoporous silica can also increase the attachment sites of microorganisms and improve the degradation rate of the color layer.

[0065] 3. In this application, chitosan / polyvinyl alcohol porous microspheres loaded with organic acid complexed iron are preferably used. Organic acid complexed iron can increase the attack of microorganisms on PE mulch and accelerate its degradation. In addition, porous microspheres containing polyvinyl alcohol improve the mechanical strength of chitosan and have a higher porosity, so the degradation rate is faster.

[0066] 4. In the present application, nanocellulose, polydopamine, manganese peroxidase, titanium dioxide aerogel and octadecyltrimethylammonium chloride are preferably used to prepare biodegradable masterbatch. Polydopamine can increase the contact fastness between manganese peroxidase and nanocellulose, and increase its temperature resistance. In addition, the coating of silica aerogel can further improve the heat resistance of manganese peroxidase and provide more attachment sites for microorganisms. Octadecyltrimethylammonium chloride can improve the dispersibility of biodegradable masterbatch and PE resin. DETAILED DESCRIPTION

[0067] The following examples further illustrate the present application in detail.

[0068] Preparation Example 1-11 of Spectrum Adjusting Pigment Masterbatch,

[0069] In the following preparation examples, the sources of raw materials are: HDPE is selected from LG of South Korea, model BE0400, LDPE is selected from Sinopec Yanshan, model LD155, LLDPE is selected from Primen of Japan, model SP4020, cellulase is selected from Shandong Longda Bioengineering, enzyme activity is 200,000 u / ml, needle-shaped wollastonite is selected from Jiangxi Guangyuan Chemical Co., Ltd., model GY4000, chitosan molecular weight is 161.16 kDa, polyvinyl alcohol molecular weight is 1800,

[0070] Preparation Example 1: 100g PE resin was kneaded at 100°C for 3min, 3g dispersant was added and kneaded for 3min, 10g chitosan porous microspheres and 20g pigment powder and 14g needle-shaped filler which were pre-mixed were added, and extruded and granulated after kneading for 15min. The extrusion temperature was: 100°C for zone 1, 150°C for zone 2, 160°C for zone 3, 170°C for zone 4, 180°C for zone 5, 200°C for zone 6, and 190°C for die. The PE resin included HDPE, LDPE and LLDPE with a mass ratio of 1:2:2, and the dispersant was fiber with a mass ratio of 1:5 The chitosan porous microspheres are prepared by dissolving chitosan in 0.2 mol / l acetic acid solution, stirring at 65°C for 5 h, ultrasonically oscillating at a frequency of 80 Hz for 10 min to obtain a 3% chitosan solution, dropping the solution into 1 mol / l sodium hydroxide solution, stirring at 120 rpm for 1 h, filtering, washing with deionized water until neutral, pre-freezing at -40°C for 200 min, and freeze-drying at -60°C to obtain chitosan porous microspheres.

[0071] Preparation Example 2: 100g PE resin was kneaded at 110°C for 5min, 1g dispersant was added and kneaded for 5min, 5g chitosan porous microspheres and 14g pigment powder and 7g needle-shaped filler which were pre-mixed were added, and extruded and granulated after kneading for 10min. The extrusion temperature was: 100°C for zone 1, 150°C for zone 2, 160°C for zone 3, 170°C for zone 4, 180°C for zone 5, 200°C for zone 6, and 190°C for die. The PE resin included HDPE, LDPE and LLDPE in a mass ratio of 1:2.5:2.5, and the dispersant was fiber in a mass ratio of 1:4. The chitosan porous microspheres are prepared by dissolving chitosan in 0.2 mol / l acetic acid solution, stirring at 65°C for 5 h, ultrasonically oscillating at a frequency of 80 Hz for 10 min to obtain a 3% chitosan solution, dropping the solution into 1 mol / l sodium hydroxide solution, stirring at 120 rpm for 1 h, filtering, washing with deionized water until neutral, pre-freezing at -40°C for 200 min, and freeze-drying at -60°C to obtain chitosan porous microspheres.

[0072] Preparation Example 3: The difference from Preparation Example 1 is that an equal amount of fatty alcohol polyoxyethylene ether is used to replace cellulase.

[0073] Preparation Example 4: The difference from Preparation Example 1 is that no chitosan porous microspheres are added.

[0074] Preparation Example 5: The difference from Preparation Example 1 is that the pigment powder is pretreated as follows:

[0075] 2 g of pigment powder was added to a mixed solution of 0.4 ml of deionized water and 100 ml of anhydrous ethanol, and after ultrasonic dispersion for 30 min, 4 ml of 25 wt% ammonia water was added, and the mixture was stirred at 25°C for 40 min to obtain a pigment stock solution;

[0076] Disperse 4 g of ethyl orthosilicate in 20 ml of anhydrous ethanol, heat to 85°C and stir for 100 min, then drip into the pigment stock solution, wash with anhydrous ethanol 3 times, wash with deionized water 3 times, vacuum dry at 60°C for 12 h, and calcine at 550°C for 3 h to obtain a coating;

[0077] Disperse hexadecyl dimethyl benzyl ammonium chloride in 100 mL of deionized water, add the coating, mix well, filter, and dry at 80° C. for 12 h. The mass ratio of hexadecyl dimethyl benzyl ammonium chloride to pigment powder is 0.02:1.

[0078] Preparation Example 6: The difference from Preparation Example 1 is that the pigment powder is pretreated as follows:

[0079] 2 g of pigment powder was added to a mixed solution of 0.4 ml of deionized water and 100 ml of anhydrous ethanol, and after ultrasonic dispersion for 30 min, 4 ml of 25 wt% ammonia water was added, and the mixture was stirred at 30 ° C for 30 min to obtain a pigment stock solution;

[0080] Disperse 5g of ethyl orthosilicate in 20ml of anhydrous ethanol, heat to 80℃ and stir for 120min, then drip into the pigment stock solution, wash with anhydrous ethanol 3 times, wash with deionized water 3 times, vacuum dry at 60℃ for 12h, and calcine at 500℃ for 5h to obtain a coating;

[0081] Disperse hexadecyl dimethyl benzyl ammonium chloride in 100 mL of deionized water, add the coating, mix well, filter, and dry at 80° C. for 12 h. The mass ratio of hexadecyl dimethyl benzyl ammonium chloride to pigment powder is 0.04:1.

[0082] Preparation Example 7: The difference from Preparation Example 6 is that hexadecyldimethylbenzylammonium chloride is not used to treat the coating, and the pretreatment of the pigment powder is completed after the coating is obtained.

[0083] Preparation Example 8: The difference from Preparation Example 6 is that tetraethyl orthosilicate is not added. The specific method is: disperse hexadecyldimethylbenzyl ammonium chloride in 100 mL of deionized water, add pigment powder, mix well, filter, and dry at 80°C for 12 hours. The mass ratio of hexadecyldimethylbenzyl ammonium chloride to pigment powder is 0.04:1.

[0084] Preparation Example 9: The difference from Preparation Example 6 is that the chitosan porous microspheres are chitosan / polyvinyl alcohol porous microspheres loaded with organic acid complexed iron, and the preparation method thereof is as follows: 4 g of chitosan is dissolved in 96 g of 0.2 mol / L acetic acid solution to prepare a chitosan solution with a concentration of 4 wt%, and 12 g of polyvinyl alcohol is dissolved in 88 g of deionized water to prepare a polyvinyl alcohol solution with a concentration of 12 wt%;

[0085] The chitosan solution and the polyvinyl alcohol solution were mixed evenly in a mass ratio of 2:1, and then dropped into a sodium hydroxide solution with a concentration of 1 mol / L, and stirred for 1 hour, filtered, washed to neutrality, pre-frozen at -20°C for 200 minutes, and vacuum dried for 6 hours to obtain chitosan / polyvinyl alcohol porous microspheres;

[0086] Prepare 250 mL of a 0.1 mol / L mixed solution of ferric nitrate nonahydrate and oxalic acid (the molar ratio of ferric nitrate nonahydrate to oxalic acid is 1:1), add 5 g of chitosan / polyvinyl alcohol porous microspheres into the mixed solution, oscillate in a constant temperature water bath at 25°C for 6 h, filter, wash with deionized water, and dry at 60°C for 12 h to obtain chitosan / polyvinyl alcohol porous microspheres loaded with organic acid complexed iron.

[0087] Preparation Example 10: The difference from Preparation Example 9 is that the chitosan porous microspheres are chitosan / polyvinyl alcohol porous microspheres, and the preparation method thereof is as follows: 4 g of chitosan is dissolved in 96 g of 0.2 mol / L acetic acid solution to prepare a chitosan solution with a concentration of 4 wt%, and 12 g of polyvinyl alcohol is dissolved in 88 g of deionized water to prepare a polyvinyl alcohol solution with a concentration of 12 wt%;

[0088] The chitosan solution and the polyvinyl alcohol solution were mixed evenly in a mass ratio of 2:1, and dropped into a sodium hydroxide solution with a concentration of 1 mol / L, while stirring for 1 hour, filtered, washed to neutrality, pre-frozen at -20°C for 200 minutes, and vacuum dried for 6 hours to obtain chitosan / polyvinyl alcohol porous microspheres.

[0089] Preparation Example 11: The difference from Preparation Example 9 is that the chitosan porous microspheres are chitosan porous microspheres loaded with organic acid complexed iron, and the preparation method thereof is as follows:

[0090] Chitosan was dissolved in 0.2 mol / l acetic acid solution, stirred at 65°C for 5 h, ultrasonically oscillated at 80 Hz for 10 min to obtain a 3% chitosan solution, dropped into 1 mol / l sodium hydroxide solution, stirred at 120 rpm for 1 h, filtered, washed with deionized water until neutral, pre-frozen at -40°C for 200 min, and freeze-dried at -60°C to obtain chitosan porous microspheres.

[0091] Prepare 250 mL of a 0.1 mol / L mixed solution of ferric nitrate nonahydrate and oxalic acid (the molar ratio of ferric nitrate nonahydrate to oxalic acid is 1:1), add 5 g of chitosan porous microspheres into the mixed solution, oscillate in a constant temperature water bath at 25°C for 6 h, filter, wash with deionized water, and dry at 60°C for 12 h to obtain chitosan porous microspheres loaded with organic acid complexed iron.

[0092] Preparation Examples 12-18 of Biodegradable Masterbatch,

[0093] In the following preparation examples, the sources of raw materials are as follows: LDPE resin is selected from Sinopec Yanshan, model LD155, cellulose nanofiber is selected from Nanjing Tianlu Nanotechnology, solid content is 2%, fiber diameter is 1-100nm, length is 500nm-200μm, manganese peroxidase is selected from Shanghai Yingxin Laboratory Equipment, CAS No. 114995-15-2, model is 5mg, dopamine hydrochloride is selected from Hefei Bomei Biotechnology, product number is DD5109.

[0094] Preparation Example 12: (1) Disperse 0.5 g of cellulose nanofibers in 20 mL of Tris-HCl buffer (0.02 M, pH = 8.5), stir for 20 min, add 0.15 g of dopamine hydrochloride, react at 30 ° C for 24 h, centrifuge, concentrate, and wash with water until neutral to obtain polydopamine-modified cellulose nanofibers;

[0095] (2) 25 U / g manganese peroxidase and polydopamine-modified cellulose nanofibers were mixed, shaken at 45 °C for 2 h, and then concentrated to obtain an intermediate;

[0096] (3) At room temperature, butyl titanate, anhydrous ethanol and a chelating agent are mixed to obtain a solution, acetic acid, deionized water and anhydrous ethanol are mixed to obtain another solution, and the former mixed solution is added dropwise to the latter solution under stirring to obtain a titanium dioxide sol, and formamide is quickly added to the sol, mixed well, and allowed to stand to obtain a titanium dioxide alcohol sol, wherein the molar ratio of butyl titanate, anhydrous ethanol, deionized water, acetic acid and formamide is 1:24:6:18:0.5, the chelating agent is acetylacetone, and the solution dropping speed is 1 drop / second;

[0097] (4) The intermediate was mixed evenly with 1.5 g of titanium dioxide alcohol sol and an aqueous solution of octadecyltrimethylammonium chloride with a concentration of 0.3 wt%, aged at 60 °C for 48 h, washed with anhydrous ethanol three times, each time for 24 h, then dried at room temperature for 24 h, heated to 60 °C and dried for 48 h, mixed with 5 g of LDPE resin, extruded, and granulated to obtain a biodegradable masterbatch. The aqueous solution of octadecyltrimethylammonium chloride was prepared by mixing 0.5 g of octadecyltrimethylammonium chloride and deionized water, and the extrusion temperature was 120 °C.

[0098] Preparation Example 13: (1) Disperse 0.4 g of cellulose nanofibers in 20 mL of Tris-HCl buffer (0.02 M, pH = 8.5), stir for 20 min, add 0.1 g of dopamine hydrochloride, react at 35 ° C for 20 h, centrifuge, concentrate, and wash with water until neutral to obtain polydopamine-modified cellulose nanofibers;

[0099] (2) 15 U / g manganese peroxidase and polydopamine-modified cellulose nanofibers were mixed, shaken at 40° C. for 3 h, and then concentrated to obtain an intermediate;

[0100] (3) At room temperature, butyl titanate, anhydrous ethanol and a chelating agent are mixed to obtain a solution, acetic acid, deionized water and anhydrous ethanol are mixed to obtain another solution, and the former mixed solution is added dropwise to the latter solution under stirring to obtain a titanium dioxide sol, and formamide is quickly added to the sol, mixed well, and allowed to stand to obtain a titanium dioxide alcohol sol, wherein the molar ratio of butyl titanate, anhydrous ethanol, deionized water, acetic acid and formamide is 1:24:6:18:0.5, the chelating agent is acetylacetone, and the solution dropping speed is 1 drop / second;

[0101] (4) The intermediate was mixed evenly with 1 g of titanium dioxide alcohol sol and an aqueous solution of octadecyltrimethylammonium chloride with a concentration of 0.2 wt%, aged at 60 °C for 48 h, washed with anhydrous ethanol three times, each time for 24 h, then dried at room temperature for 24 h, heated to 60 °C and dried for 48 h, mixed with 3 g of LDPE resin, extruded, and granulated to obtain a biodegradable masterbatch. The aqueous solution of octadecyltrimethylammonium chloride was prepared by mixing 0.2 g of octadecyltrimethylammonium chloride and deionized water, and the extrusion temperature was 120 °C.

[0102] Preparation Example 14: The difference from Preparation Example 12 is that no octadecyltrimethylammonium chloride aqueous solution is used.

[0103] Preparation Example 15: The difference from Preparation Example 12 is that manganese peroxidase was not added.

[0104] Preparation Example 16: The difference from Preparation Example 12 is that no titanium dioxide sol is added.

[0105] Preparation Example 17: The difference from Preparation Example 12 is that Tris-HCl buffer and dopamine hydrochloride are not added, 0.5 g of cellulose nanofibers, 20 mL of deionized water and 25 U / g of manganese peroxidase are mixed, shaken at 45°C for 2 h, and then concentrated to obtain an intermediate, and the rest of the method is the same as Preparation Example 12.

[0106] Preparation Example 18: 0.5 g of cellulose nanofibers and 5 g of LDPE resin were mixed, extruded, and granulated to obtain biodegradable masterbatch at an extrusion temperature of 180°C.

[0107] Example:

[0108] The sources of the raw materials in the embodiment are as follows: HDPE is selected from LG of South Korea, model BE0400, LDPE is selected from Sinopec Yanshan, model LD155, LLDPE is selected from Primen of Japan, model SP4020, bamboo fiber is selected from Hongqing Hemp Industry of Tongling City, item number Ba-001, length 10 mm, white pigment powder is titanium dioxide selected from Fangyi Chemical Additives of Gaoyi County, item number FY13, model RG-18P, black pigment powder is selected from Suzhou Liyan Chemical, item number 311765, brand N330, silver pigment powder is selected from Lingshou County Shiyun Mining Products, item number 101, red pigment powder is iron oxide red powder, selected from Lingshou County Yaxu Mining Products, model 130, item number RQ1301, blue pigment powder is iron oxide blue, selected from Shijiazhuang Yingmei Chemical Products, item number YM211123-A, yellow pigment powder is yellow lead powder, selected from Zhengzhou Xinghong Chemical Technology, item number 1456964.

[0109] Example 1: A fully biodegradable PE mulch film with specific spectral absorption characteristics, with a thickness of 12 μm, comprising a base layer and a color layer located on one side of the base layer, the base layer comprising 80 g PE resin, 2 g biodegradable masterbatch and 20 g filler, the biodegradable masterbatch is made from Preparation Example 12, the PE resin comprises HDPE, LDPE and LLDPE in a mass ratio of 1:2:2, and the filler is calcium carbonate; the raw materials of the color layer include: 1.5 g biodegradable masterbatch made from Preparation Example 12, 5 g spectrum-adjusting pigment masterbatch made from Preparation Example 1, 0.5 g plant fiber, 1.5 g antioxidant, 2 g light stabilizer and 2 g dehumidifier, wherein the pigment powder in the spectrum-adjusting pigment masterbatch is a silver-gray pigment powder mixed with 70% white pigment powder, 15% black pigment powder and 15% silver pigment powder, the plant fiber is bamboo fiber, the antioxidant is antioxidant 1010, the light stabilizer is zinc oxide, and the dehumidifier is calcium chloride.

[0110] The method for preparing the above-mentioned fully biodegradable PE mulch film having specific spectral absorption characteristics comprises the following steps:

[0111] The PE resin and the biodegradable masterbatch were mixed evenly, extruded and granulated to obtain the base layer raw material, the feed port temperature was 90°C, the middle section temperature was 120°C, and the die head temperature was 160°C;

[0112] The biodegradable masterbatch, the spectrum adjustment pigment masterbatch, the plant fiber, the antioxidant, the light stabilizer and the dehumidifier are uniformly mixed, and the color layer raw material is obtained by extrusion granulation. The feed temperature is 80°C, the middle section temperature is 110°C, and the head temperature is 150°C.

[0113] The base layer material and the color layer material are placed in two barrels of a double-layer co-extrusion film blowing machine respectively, and co-extruded and blown, and then cooled and rolled to obtain a PE ground film containing a base layer and a color layer located on one side of the base layer, with a blowing ratio of 3.

[0114] Example 2: A fully biodegradable PE mulch film with specific spectral absorption characteristics, with a thickness of 12 μm, includes a base layer and a color layer located on both sides of the base layer, the base layer contains 70 g PE resin, 1 g biodegradable masterbatch and 10 g filler, the biodegradable masterbatch is made by Preparation Example 13, the PE resin includes HDPE, LDPE and LLDPE in a mass ratio of 1:2.5:2.5, the filler is calcium carbonate, and the raw materials of the color layer include: 1 g biodegradable masterbatch made by Preparation Example 13, 2 g spectrum-adjusting pigment masterbatch made by Preparation Example 2, 0.1 g plant fiber, 1 g antioxidant, 1 g light stabilizer and 1 g dehumidifier, wherein the pigment powder in the spectrum-adjusting pigment masterbatch is a silver-gray pigment powder mixed with 70% white pigment powder, 15% black pigment powder and 15% silver pigment powder, the plant fiber is bamboo fiber, the antioxidant is antioxidant 1010, the light stabilizer is zinc oxide, and the dehumidifier is calcium chloride.

[0115] The method for preparing the above-mentioned fully biodegradable PE mulch film having specific spectral absorption characteristics comprises the following steps:

[0116] The PE resin and the biodegradable masterbatch were mixed evenly, extruded and granulated to obtain the base layer raw material, the feed port temperature was 90°C, the middle section temperature was 120°C, and the die head temperature was 160°C;

[0117] The biodegradable masterbatch, the spectrum adjustment pigment masterbatch, the plant fiber, the antioxidant, the light stabilizer and the dehumidifier are uniformly mixed, and the color layer raw material is obtained by extrusion granulation. The feed temperature is 80°C, the middle section temperature is 110°C, and the head temperature is 150°C.

[0118] The base layer material and the color layer material are placed in three barrels of a three-layer co-extrusion film blowing machine respectively, and are co-extruded and blown, and then cooled and rolled to obtain a PE ground film containing a base layer and color layers on both sides of the base layer, with a blowing ratio of 3.

[0119] Example 3: A fully biodegradable PE mulch film with specific spectral absorption characteristics, with a thickness of 12 μm, comprising a base layer and two color layers located on one side of the base layer, the base layer comprising 95 g PE resin, 3 g biodegradable masterbatch and 30 g filler, the biodegradable masterbatch is made by Preparation Example 12, the PE resin comprises HDPE, LDPE and LLDPE in a mass ratio of 1:2:2.5, and the filler is calcium carbonate; the raw materials of the color layer include: 2 g biodegradable masterbatch made by Preparation Example 12, 10 g spectrum-adjusting pigment masterbatch made by Preparation Example 1, 1 g plant fiber, 3 g antioxidant, 3 g light stabilizer and 3 g dehumidifier, wherein the pigment powder in the spectrum-adjusting pigment masterbatch is a silver-gray pigment powder mixed with 70% white pigment powder, 15% black pigment powder and 15% silver pigment powder, the plant fiber is bamboo fiber, the antioxidant is antioxidant 1010, the light stabilizer is zinc oxide, and the dehumidifier is calcium chloride.

[0120] The method for preparing the above-mentioned fully biodegradable PE mulch film having specific spectral absorption characteristics comprises the following steps:

[0121] The PE resin and the biodegradable masterbatch were mixed evenly, extruded and granulated to obtain the base layer raw material, the feed port temperature was 90°C, the middle section temperature was 120°C, and the die head temperature was 160°C;

[0122] The biodegradable masterbatch, the spectrum adjustment pigment masterbatch, the plant fiber, the antioxidant, the light stabilizer and the dehumidifier are uniformly mixed, and the color layer raw material is obtained by extrusion granulation. The feed temperature is 80°C, the middle section temperature is 110°C, and the head temperature is 150°C.

[0123] The base layer raw material and the color layer raw material are placed in three barrels of a three-layer co-extrusion film blowing machine respectively, and are co-extruded and blown, and then cooled and rolled to obtain a PE ground film containing a base layer and two color layers located on one side of the base layer, with a blowing ratio of 3.

[0124] Example 4: A fully biodegradable PE mulch film with specific spectral absorption characteristics, which is different from Example 1 in that the pigment powder in the spectrum-adjusting pigment masterbatch is black pigment powder.

[0125] Example 5: A fully biodegradable PE mulch film with specific spectral absorption characteristics. The difference from Example 1 is that the pigment powder in the spectrum regulating pigment masterbatch is a silver-black pigment powder made by mixing 50% silver pigment powder and 50% black pigment powder.

[0126] Example 6: A fully biodegradable PE mulch film with specific spectral absorption characteristics, which is different from Example 1 in that the pigment powder in the spectrum-adjusting pigment masterbatch is red pigment powder.

[0127] Example 7: A fully biodegradable PE mulch film with specific spectral absorption characteristics, which is different from Example 1 in that the pigment powder in the spectrum-adjusting pigment masterbatch is blue pigment powder.

[0128] Example 8: A fully biodegradable PE mulch film with specific spectral absorption characteristics, which is different from Example 1 in that the pigment powder in the spectrum-adjusting pigment masterbatch is yellow pigment powder.

[0129] Example 9: A fully biodegradable PE mulch film with specific spectral absorption characteristics. The difference from Example 1 is that the spectrum regulating pigment masterbatch is made from Preparation Example 3.

[0130] Example 10: A fully biodegradable PE mulch film with specific spectral absorption characteristics. The difference from Example 1 is that the spectrum regulating pigment masterbatch is made from Preparation Example 4.

[0131] Example 11: A fully biodegradable PE mulch film with specific spectral absorption characteristics. The difference from Example 1 is that the spectrum regulating pigment masterbatch is made from Preparation Example 5.

[0132] Example 12: A fully biodegradable PE mulch film with specific spectral absorption characteristics. The difference from Example 1 is that the spectrum regulating pigment masterbatch is made from Preparation Example 6.

[0133] Example 13: A fully biodegradable PE mulch film with specific spectral absorption characteristics. The difference from Example 12 is that the spectrum regulating pigment masterbatch is made from Preparation Example 7.

[0134] Example 14: A fully biodegradable PE mulch film with specific spectral absorption characteristics. The difference from Example 12 is that the spectrum regulating pigment masterbatch is made from Preparation Example 8.

[0135] Example 15: A fully biodegradable PE mulch film with specific spectral absorption characteristics. The difference from Example 12 is that the spectrum regulating pigment masterbatch is made from Preparation Example 9.

[0136] Example 16: A fully biodegradable PE mulch film with specific spectral absorption characteristics, which is different from Example 15 in that the spectrum regulating pigment masterbatch is made from Preparation Example 10.

[0137] Example 17: A fully biodegradable PE mulch film with specific spectral absorption characteristics. The difference from Example 15 is that the spectrum regulating pigment masterbatch is made from Preparation Example 11.

[0138] Example 18: A fully biodegradable PE ground film with specific spectral absorption characteristics. The difference from Example 15 is that the biodegradable masterbatch in the base layer and the color layer is made from Preparation Example 14.

[0139] Example 19: A fully biodegradable PE mulch film with specific spectral absorption characteristics. The difference from Example 1 is that the biodegradable masterbatch in the base layer and the color layer is made from Preparation Example 15.

[0140] Example 20: A fully biodegradable PE ground film with specific spectral absorption characteristics. The difference from Example 1 is that the biodegradable masterbatch in the base layer and the color layer is made from Preparation Example 16.

[0141] Example 21: A fully biodegradable PE ground film with specific spectral absorption characteristics. The difference from Example 1 is that the biodegradable masterbatch in the base layer and the color layer is made from Preparation Example 17.

[0142] Example 22: A fully biodegradable PE ground film with specific spectral absorption characteristics. The difference from Example 1 is that the biodegradable masterbatch in the base layer and the color layer is made from Preparation Example 18.

[0143] Example 23: A fully biodegradable PE mulch film with specific spectral absorption characteristics. The difference from Example 1 is that no spectrum adjustment masterbatch is added to the color layer, and the raw materials of the color layer include: 1.5g of biodegradable masterbatch made by Preparation Example 12, 0.5g of plant fiber, 1.5g of antioxidant, 2g of light stabilizer and 2g of dehumidifier, the plant fiber is bamboo fiber, the antioxidant is antioxidant 1010, the light stabilizer is zinc oxide, and the dehumidifier is calcium chloride.

[0144] Comparative Example:

[0145] Comparative Example 1: A fully biodegradable PE mulch film with specific spectral absorption characteristics, which is different from Example 1 in that no biodegradable masterbatch is added to the color layer.

[0146] Comparative Example 2: A fully biodegradable PE mulch film with specific spectral absorption characteristics, which is different from Example 1 in that no biodegradable masterbatch is added to the base layer and no biodegradable masterbatch is added to the color layer.

[0147] Performance testing:

[0148] 1. Detection of color uniformity of PE ground film: Prepare PE ground film according to the method in Examples 1-22, and detect the color uniformity and dispersion of the PE ground film according to the following method, and record the test results in Table 1.

[0149] 1. Color uniformity: It is expressed by the color difference index △E. Take 20 samples of PE mulch evenly in the vertical and horizontal directions within a large area of ​​1m×25mm, measure the color difference index △E on a colorimeter, add the color difference index △E of all samples and take the average value. The smaller the average value, the better the color uniformity.

[0150] 2. Dispersion: Visually inspect whether there are obvious color spots and spots in a large area, observe whether there are detectable color clumps and stripes through light, measure the diameter of the color spots or spots, and record the number of color spots within a range of 20cm×20cm. The smaller the diameter of the color spot and the smaller the number of color spots in the range, the better the dispersion.

[0151] Table 1 Coloring performance test results of fully biodegradable PE mulch films of different colors

[0152] project △E Color point diameter / mm Number of color dots / 20cm×20cm Example 1 0.21 0.35 6 Example 2 0.22 0.38 5 Example 3 0.24 0.36 7 Example 4 0.22 0.37 5 Example 5 0.23 0.36 6 Example 6 0.22 0.35 5 Example 7 0.23 0.37 6 Example 8 0.24 0.38 6 Example 9 0.28 0.42 7 Example 10 0.22 0.37 6 Embodiment 11 0.14 0.26 3 Example 12 0.12 0.24 3 Embodiment 13 0.19 0.33 5 Embodiment 14 0.16 0.28 4 Embodiment 15 0.13 0.25 3 Example 16 0.14 0.27 3 Embodiment 17 0.12 0.24 4 Embodiment 18 0.27 0.42 9 Embodiment 19 0.22 0.35 6 Embodiment 20 0.21 0.37 5 Embodiment 21 0.23 0.36 6 Embodiment 22 0.22 0.35 5

[0153] Combining Examples 1-3 and the data in Table 1, it can be seen that the spectrum regulating pigment masterbatch prepared by Preparation Example 1 and Preparation Example 2, wherein the pigment powder is silver-gray, the prepared PE film is uniformly colored, the color difference △E is less than 0.25, and the color point diameter is small and the distribution is small.

[0154] Compared with Example 1, only the color of the pigment powder is different in Examples 4-8. It can be seen that the test data in Table 1 is not much different from that in Example 1, and the PE mulch has similar color uniformity.

[0155] In Example 9, the spectrum-adjusting pigment masterbatch prepared in Preparation Example 3 was used, wherein an equal amount of fatty alcohol polyoxyethylene ether was used to replace cellulase. As shown in Table 1, the color dispersion uniformity on the PE mulch prepared in Example 9 was reduced.

[0156] Compared with Example 1, Example 10 uses the spectrum regulating pigment masterbatch prepared in Preparation Example 4, wherein chitosan porous microspheres are not added. It can be seen that the detection data of the PE mulch is similar to that of Example 1, indicating that the addition of chitosan porous microspheres has no significant effect on the coloring of the PE mulch.

[0157] In Example 11 and Example 12, the spectrum regulating pigment masterbatch prepared in Preparation Example 5 and Preparation Example 6 is used respectively. Compared with Preparation Example 1 in Example 1, Preparation Examples 5 and Preparation Examples 6 use ethyl orthosilicate, hexadecyldimethylbenzylammonium chloride, etc. to pretreat the pigment powder. It can be seen from the data in Table 1 that the PE mulch prepared in Example 11 and Example 12 has better color uniformity, and the surface color spots are smaller and fewer.

[0158] Compared with Example 12, Example 13 uses the spectrum regulating pigment masterbatch prepared in Preparation Example 7, wherein the coating containing silica and pigment powder is not post-treated with hexadecyl dimethyl benzyl ammonium chloride. It can be seen that the color difference on the surface of the PE mulch increases slightly, while the color points increase.

[0159] In Example 14, the spectrum regulating pigment masterbatch prepared in Preparation Example 8 was used. Compared with Example 12, the pigment powder was not coated with mesoporous silica obtained by calcining the hydrolysis of ethyl orthosilicate to form silica. It can be seen that the color difference uniformity of the PE mulch film was slightly reduced.

[0160] Compared with Example 12, Example 15 uses the spectrum regulating pigment masterbatch prepared in Preparation Example 9, and the chitosan porous microspheres used are chitosan / polyvinyl alcohol porous microspheres loaded with organic acid complexed iron. It can be seen that the color uniformity of the PE mulch in Table 1 does not change much.

[0161] The spectrum-adjusting pigment masterbatch prepared in Preparation Example 10 was used in Example 16, and the spectrum-adjusting pigment masterbatch prepared in Preparation Example 11 was used in Example 17. From the comparison of the data in Table 1, it can be seen that the spectrum-adjusting pigment masterbatch prepared in Example 16 and Example 17 has little effect on the color uniformity of the PE mulch.

[0162] In Example 18, the biodegradable masterbatch prepared in Preparation Example 14 was used, in which octadecyltrimethylammonium chloride was not used for treatment. Compared with Example 1, the color difference uniformity of the PE mulch film was slightly worse, indicating that the biodegradable masterbatch can also improve the dispersibility of the pigment powder in the PE mulch film to a certain extent.

[0163] In Examples 19 to 22, the biodegradable masterbatches prepared in Preparation Examples 15, 16, 17 and 18 were used respectively. The data in Table 1 show that the silver-gray PE mulch prepared in Examples 19 to 22 is more evenly colored, indicating that the biodegradable masterbatches prepared in Examples 15 to 18 have little effect on the coloring properties of the PE mulch.

[0164] 2. Detection of plant growth under different colors of PE films:

[0165] 1. Fresh weight of Chinese cabbage per plant: A district in Shanghai was selected for the pilot project. The test material was the common small yellow and white cabbage on the market. A potted plant test was carried out. The specifications of the test pots were 59 cm × 20 cm × 14 cm, and the test soils were 650 g of coconut bricks, 100 g of nutrient soil and 150 g of earthworm fertilizer per pot; the colored PE mulch prepared in Example 1 and Examples 4-8 and the transparent mulch prepared in Example 23 were used to build a growth shed, and the Chinese cabbage seedlings with similar growth were planted in the pots at a density of 8 plants per pot. A growth shed was built for each pot as one treatment, and fertilizer and water management was carried out uniformly. After the vegetables entered the picking period, Chinese cabbage with similar growth conditions was selected for whole-plant sampling, and the whole plant was weighed using an electronic scale. Each treatment was repeated 3 times for testing the fresh weight of Chinese cabbage per plant, and the test results are recorded in Table 2.

[0166] 2. Insect population reduction rate and yield of peanuts: The test site was selected from Xiangcheng Town, Jining, Shandong. The test soil was sandy loam with medium fertility. The test peanut variety was Luhua No. 8. The planting method was spring peanuts. The colored PE films prepared in Examples 1 and Examples 4-8, the transparent film prepared in Example 23, and a commercially available transparent film (Zibo District Xindian Jicai Plastic Products, 0.12 mm) were used for testing. The area of ​​each mulch film treatment plot was 20×4=80 m 2 , repeated 3 times, protection rows were set at the edge of the experimental field, and a 10-point chessboard sampling method was used in each plot in the field, with 5 piles of peanuts at each point. The number of spider mites on each pile of peanuts was investigated and recorded during the peak period of spider mites, and the insect population reduction rate was calculated: insect population reduction rate / %=(1-the number of insects in the treatment area / the number of insects in the transparent membrane)×100. The test results are recorded in Table 2; a 2-meter 4-row investigation method was used and the number of investigated piles was recorded. Each treatment was repeated 3 times, and only the effective weight was weighed (the diseased and rotten fruits that were severely damaged and had no yield were removed). The weight of 100 peanuts was weighed after the pods were dried.

[0167] 3. Growth rate of tomatoes: Tomatoes (Taiwan Red, China) were used as test materials, and the PE films prepared in Examples 1, 4-8, and 23 were used as test materials. The area of ​​each cultivation bed was 5.25 m 2 Each cell has an area of ​​15.75m 2 Each treatment was repeated 3 times, with a row spacing of 80 cm and a plant spacing of 40 cm, and unified water and fertilizer management; after transplanting and seedling acclimatization, 5 representative plants were selected from each treatment, and the plant height and stem diameter were measured 4 weeks later, and the relative growth rate of plant height and stem volume were calculated, and the test results are recorded in Table 2.

[0168] Table 2 Effects of fully biodegradable PE mulch on the growth characteristics of different plants

[0169] project Fresh weight of Chinese cabbage / g Peanut insect population decline rate / % Weight of 100 peanuts / kg Relative growth rate of tomato plant height (cm / d) Relative growth rate of tomato stem volume (mm / d) Example 1 (silver grey) 19.89 74.67 0.189 0.0415 0.074 Example 4 (black) 20.91 14.41 0.146 0.0413 0.081 Example 5 (silver black) 20.34 55.68 0.195 0.0420 0.076 Example 6 (red) 22.11 62.54 0.141 0.0411 0.077 Example 7 (blue) 16.24 60.34 0.138 0.0419 0.078 Example 8 (yellow) 19.54 58.92 0.135 0.0408 0.071 Example 23 (Transparent Film) 20.82 8.63 0.153 0.0418 0.075

[0170] It can be seen from the data in Table 2 that under the blue film treatment, the fresh weight of Chinese cabbage is the lowest, and is significantly lower than that of red film, yellow film and black film. The black film has a greater effect on the insect attenuation rate of peanuts, and the red film has a certain effect on the growth rate of tomatoes. It can be seen that different plants require specific spectrum irradiation. Therefore, it is necessary to select PE mulch with specific spectral absorption characteristics to obtain better growth trends and insect prevention effects.

[0171] 3. Mechanical strength and degradation rate test of fully biodegradable PE mulch:

[0172] 1. Tear strength: Test according to GB / T16578.1-2008 "Determination of tear resistance of plastic films and sheets", test 3 groups for each embodiment or comparative example, and take the average value.

[0173] 2. Puncture resistance: Test according to GB / T37841-2019 "Test method for puncture resistance of plastic films and sheets".

[0174] 3. Biodegradation test: The natural soil landfill method is used for determination. 10g of 10mm×10 mm sample is placed in a 100mm×100mm×100mm soil pit, and the sample is 10mm away from the soil. The soil selected is loose farmland, the soil pH value is 6-8, and the humidity is >80%. The experiment is carried out in the open air; after different landfill times, the weight of the remaining sample is measured to determine its biodegradability, and the weight loss rate (%) = (initial sample mass-remaining sample weight) / initial sample mass×100.

[0175] Table 3 Mechanical properties and degradation rate of fully biodegradable PE mulch film

[0176]

[0177] Combined with the test data of the fully biodegradable PE mulch in Table 3, it can be seen that the PE mulch of different colors prepared in Examples 1-8 has better tear strength and puncture resistance, and has a fast biodegradation rate, and its degradation rate can reach more than 94% in 16 weeks.

[0178] In Example 9, the spectrum regulating pigment masterbatch prepared in Preparation Example 3 was used, wherein fatty alcohol polyoxyethylene ether was used in equal amounts to replace cellulase. As shown in Table 3, the PE mulch prepared in Example 9 was not much different from that in Example 1 in terms of tear strength, puncture resistance, and degradation rate, indicating that fatty alcohol polyoxyethylene ether had little effect on the degradation rate of PE mulch.

[0179] Example 10 Compared with Example 1, the spectrum regulating pigment masterbatch prepared in Preparation Example 4 was used, in which chitosan porous microspheres were not added. It can be seen that the biodegradation rate of the PE mulch film decreased, but its tear strength increased. It may be that the brittleness of the chitosan porous microspheres affected the tensile resistance of the PE mulch film.

[0180] In Example 11 and Example 12, the spectrum regulating pigment masterbatch prepared in Preparation Example 5 and Preparation Example 6 is used respectively. Compared with Preparation Example 1 in Example 1, Preparation Examples 5 and Preparation Examples 6 use tetraethyl orthosilicate, hexadecyldimethylbenzyl ammonium chloride, etc. to pretreat the pigment powder. It can be seen from the data in Table 3 that the tear strength and puncture resistance of the PE mulch prepared in Example 11 and Example 12 do not change much, but the biodegradation rate increases.

[0181] Compared with Example 12, Example 13 uses the spectrum regulating pigment masterbatch prepared in Preparation Example 7, wherein hexadecyl dimethyl benzyl ammonium chloride is not used for post-treatment of the coating containing silica and pigment powder. From the comparison of the data in Table 3, it can be seen that the biodegradation rate of the PE mulch prepared in Example 13 does not change much, but the mechanical strength is slightly reduced.

[0182] In Example 14, the spectrum regulating pigment masterbatch prepared in Preparation Example 8 was used. Compared with Example 12, the pigment powder was not coated with mesoporous silica obtained by calcining the hydrolysis of tetraethyl orthosilicate to form silica. It can be seen that the tear strength of the PE mulch prepared in this way did not change much, but the biodegradation rate decreased. Therefore, using tetraethyl orthosilicate to form mesoporous silica on the pigment powder can improve the biodegradation rate of the PE mulch.

[0183] Compared with Example 12, Example 15 adopts the spectrum regulating pigment masterbatch prepared in Preparation Example 9, and the chitosan porous microspheres used are chitosan / polyvinyl alcohol porous microspheres loaded with organic acid complexed iron. The data in Table 3 show that the biodegradation rate of the PE mulch prepared in Example 15 is significantly increased, which can be increased to more than 98% in 16 weeks.

[0184] In Example 16, the spectrum regulating pigment masterbatch prepared in Preparation Example 10 was used, and in Example 17, the spectrum regulating pigment masterbatch prepared in Preparation Example 11 was used. Compared with Example 15 using the spectrum regulating pigment masterbatch prepared in Preparation Example 9, the biodegradation rate of the PE mulch prepared in Example 16 decreased, and the breaking strength of the PE film prepared in Example 17 weakened and the degradation rate slightly decreased. It can be seen that the use of organic acid complexed iron and polyvinyl alcohol can respectively increase the degradation rate and mechanical strength of the PE mulch.

[0185] In Example 18, the biodegradable masterbatch prepared in Preparation Example 14 was used. Compared with Example 1, octadecyltrimethylammonium chloride was not used. It can be seen that the biodegradation rate of the prepared PE mulch film did not change much, but its tear strength decreased.

[0186] Compared with Example 1, Example 19 uses the biodegradable masterbatch prepared in Preparation Example 15, wherein no manganese peroxidase is added. It can be seen that the data comparison in Table 3 shows that the biodegradation rate of the PE mulch prepared in Example 19 is significantly reduced.

[0187] In Example 20, the biodegradable masterbatch prepared in Preparation Example 16 was used, to which no titanium dioxide sol was added. Compared with Example 1, the biodegradation rate of the PE mulch prepared in Example 20 was slower, indicating that titanium dioxide aerogel can increase the thermal stability of manganese peroxidase and reduce the effect of temperature on its activity.

[0188] Compared with Example 1, Example 21 uses the biodegradable masterbatch prepared in Preparation Example 17, to which Tris-HCl buffer and dopamine hydrochloride are not added. It can be seen from the data in Table 3 that the biodegradation rate of the PE mulch prepared in Example 21 decreases, but its tear strength does not change much.

[0189] The biodegradable masterbatch prepared in Preparation Example 18 is used in Example 22. It is prepared by extrusion granulation after mixing LDPE resin and cellulose nanofibers. Compared with Example 1, its biodegradation rate is significantly slower.

[0190] In Example 23, no spectrum regulating pigment masterbatch was added to the inner color layer to make a transparent PE mulch film. It can be seen that its mechanical strength was slightly reduced and the degradation rate was also reduced, indicating that the spectrum regulating pigment masterbatch can improve the degradation rate of the PE mulch film to a certain extent.

[0191] Compared with Example 1, in Comparative Example 1, no biodegradable masterbatch was added to the color layer, while in Comparative Example 2, no biodegradable masterbatch was added to both the base layer and the color layer. The data in Table 3 show that the biodegradation rate of the PE mulch prepared in Comparative Example 1 and Comparative Example 2 was significantly slowed down.

[0192] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A fully biodegradable PE mulch film with specific spectral absorption characteristics, characterized in that: It comprises a base layer and a color layer located on at least one side of the base layer, wherein the color layer is provided as at least one layer; The base layer comprises the following raw materials in parts by weight: 70-95 parts of PE resin, 1-3 parts of biodegradable masterbatch and 0-30 parts of filler; The color layer comprises the following raw materials in parts by weight: 1-1.5 parts of biodegradable masterbatch, 2-5 parts of spectrum adjustment pigment masterbatch, 0.1-0.5 parts of plant fiber, 1-1.5 parts of antioxidant, 1-2 parts of light stabilizer, and 1-2 parts of dehumidifier; The spectrum adjustment pigment masterbatch comprises the following raw materials in parts by weight: 100 parts of PE resin, 14-20 parts of pigment powder, 1-3 parts of dispersant, 7-14 parts of needle-shaped filler and 5-10 parts of chitosan porous microspheres; The chitosan porous microspheres are chitosan / polyvinyl alcohol porous microspheres loaded with organic acid complexed iron; The pigment powder is selected from at least one of white pigment powder, black pigment powder, red pigment powder, yellow pigment powder, blue pigment powder, green pigment powder, purple pigment powder, orange pigment powder, silver pigment powder, gray pigment powder and silver-gray pigment powder; The pigment powder is pretreated by the following method: Add the pigment powder to a mixture of deionized water and anhydrous ethanol, add ammonia water after ultrasonic dispersion, and stir at 25-30°C for 30-40 minutes to obtain a pigment stock solution; Disperse tetraethyl orthosilicate in anhydrous ethanol, heat to 80-85°C and stir for 100-120 minutes, then drip into the pigment stock solution, wash with anhydrous ethanol and deionized water in sequence after complete dripping, vacuum dry, calcine at 500-550°C for 3-5 hours to obtain a coating, the mass ratio of tetraethyl orthosilicate to pigment powder is 2-2.5:1; Disperse hexadecyl dimethyl benzyl ammonium chloride in deionized water, add the coating, mix evenly, filter and dry, and the mass ratio of hexadecyl dimethyl benzyl ammonium chloride to pigment powder is 0.02-0.04:

1.

2. The fully biodegradable PE mulch film with specific spectral absorption characteristics according to claim 1 is characterized in that: The dispersant comprises cellulase and fatty alcohol polyoxyethylene ether in a mass ratio of 1:4-5.

3. The fully biodegradable PE mulch film with specific spectral absorption characteristics according to claim 1 is characterized in that: The biodegradable masterbatch is prepared by the following method: The cellulose nanofibers are dispersed in a Tris-HCl buffer, stirred evenly, and dopamine hydrochloride is added, reacted at 30-35° C. for 20-24 hours, centrifuged, concentrated, and washed with water until neutral, to obtain polydopamine-modified cellulose nanofibers; The manganese peroxidase and polydopamine-modified cellulose nanofibers are mixed, shaken at 40-45° C. for 2-3 hours, and then concentrated to obtain an intermediate; The intermediate is mixed evenly with titanium dioxide alcohol sol and 0.2-0.3wt% octadecyltrimethylammonium chloride aqueous solution, aged and dried, and then mixed with LDPE resin, extruded and granulated to obtain biodegradable masterbatch.

4. The fully biodegradable PE mulch film with specific spectral absorption characteristics according to claim 1, characterized in that: The needle-shaped filler is selected from at least one of needle-shaped alumina, needle-shaped aluminum hydroxide, needle-shaped calcium silicate and needle-shaped wollastonite.

5. The fully biodegradable PE mulch film with specific spectral absorption characteristics according to claim 1, characterized in that: The PE resin includes HDPE, LDPE and LLDPE in a mass ratio of 1:2-2.5:2-2.

5.

6. The fully biodegradable PE mulch film with specific spectral absorption characteristics according to claim 1, characterized in that: The filler is selected from at least one of calcium carbonate and secondary recycled PE mulch material; The plant fiber is selected from at least one of bamboo fiber, wheat straw fiber and hemp fiber; The antioxidant is selected from at least one of antioxidant 1010, antioxidant 168, antioxidant 1076, and antioxidant 330; The light stabilizer is selected from at least one of o-hydroxybenzophenone, benzotriazole, phenyl salicylate, zinc oxide and titanium dioxide; The dehumidifier is selected from at least one of anhydrous calcium chloride, diatomaceous earth, silica gel, activated carbon, 4A molecular sieve activation powder and 3A molecular sieve activation powder.

7. The method for preparing the fully biodegradable PE mulch film having specific spectral absorption characteristics according to any one of claims 1 to 6, characterized in that: The following steps are involved: The PE resin and the biodegradable masterbatch are mixed evenly, and extruded into granules to obtain the base layer raw material; The biodegradable masterbatch, the spectrum regulating pigment masterbatch, the plant fiber, the antioxidant, the light stabilizer and the dehumidifier are uniformly mixed, and then extruded into granules to obtain the color layer raw material; The base layer material and the color layer material are co-extruded and blow-molded to obtain a PE ground film, wherein the color layer is located on at least one side of the base layer, and at least one color layer is provided.

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