A modified fully biodegradable mulch film with fertilizer function and its preparation method

Abstract

A modified fully biodegradable mulch film with a fertilizer effect, characterized in that the raw materials include the following components in parts by weight: 60-100 parts of biodegradable resin, 5-30 parts of modified lignin, 0-10 parts of mineral powder, and 2-15 parts of an auxiliary agent; wherein the modified lignin is a phosphonic acid compound ethylenediamine salt lignin. The above raw materials are mixed, extruded and granulated, and the particles are co-extruded and blown into film to obtain the modified fully biodegradable mulch film with a fertilizer effect. The modified fully biodegradable mulch film with a fertilizer effect prepared by the method of the present invention has the following advantages: the addition of lignin, which is widely available, inexpensive, and easily available, achieves efficient resource utilization; and the modified mulch film has advantages such as good toughness and tensile strength, as well as good degradation performance. After degradation, it can increase the nitrogen, phosphorus, and potassium fertility of the soil, and has a good effect on protecting the environment and soil quality.

Description

Technical Field

[0001] The invention belongs to the field of degradable composite materials, and particularly relates to a modified fully biodegradable ground film with fertilizer function and a preparation method thereof. Background Art

[0002] Mulching crops with mulch has the functions of increasing temperature and retaining moisture, resisting drought and saving water, and suppressing weeds. However, traditional agricultural polyethylene mulch does not degrade. The thickness of PE mulch on the market is mostly less than 10μm, which is a de-surfaced product and is very difficult to recycle, causing a large amount of white pollution in farmland. The residual film seriously affects the decomposition of soil humus and is affected by air permeability and water permeability, resulting in damage to the soil structure, which has extremely adverse effects on the environment and agricultural production.

[0003] Promoting fully biodegradable mulch to replace traditional PE mulch is a new trend in addressing white pollution in farmland. Currently, many regions have begun researching and promoting biodegradable mulch, but these mulch still present the following challenges: 1. Expensive raw materials and high costs; 2. Poor performance; Mechanical mulching and tillage cannot meet usage requirements; 3. Short lifespans and uncontrollable degradation.

[0004] Therefore, this field urgently needs to develop a fully biodegradable mulch film with a wide source of raw materials, low price, and green environmental protection to achieve efficient utilization of resources. The product has excellent mechanical properties and is easy to process and synthesize, which can meet the needs of heat preservation and moisture retention during the crop growth period. In the later process of mulch film degradation, it can be used as fertilizer to continuously ensure crop growth and increase crop yields. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the problems in the prior art of fully biodegradable films that are difficult to meet usage requirements for moisture and fertilizer conservation, have uncontrollable degradation periods, poor performance, and high costs.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions.

[0007] A modified fully biodegradable mulch film with fertilizer function, the raw materials of which include the following components in parts by weight: 60-100 parts of biodegradable resin, 5-30 parts of modified lignin, 0-10 parts of mineral powder, and 2-15 parts of additives;

[0008] Wherein, the modified lignin is phosphonic acid compound ethylenediamine salt lignin.

[0009] Preferably, the biodegradable resin includes polybutylene adipate / terephthalate (PBAT) and / or polylactic acid (PLA).

[0010] Preferably, the mineral powder includes talc and / or calcium carbonate.

[0011] Preferably, the auxiliary agents include a crosslinking agent, a plasticizer, a dispersant, an antioxidant and a light stabilizer.

[0012] Preferably, the cross-linking agent includes one or more of 1,4-di-tert-butyl peroxide isopropylbenzene (BIBP), dibenzoyl peroxide (BPO) and German BASF ADR-4370S (ADR), more preferably BIBP and / or ADR;

[0013] And / or, the plasticizer includes one or more of tributyl citrate (TBC), acetyl tri-n-butyl citrate (ATBC), dioctyl phthalate (DOP), and xylitol, more preferably one or more of ATBC, TBC, and DOP;

[0014] And / or, the dispersant comprises one or more of stearic acid, erucamide, and ethylene bisstearamide, preferably stearic acid and / or erucamide;

[0015] And / or, the antioxidant includes one or more of 2,6-di-tert-butyl-4-methylphenol and tris(2,4-di-tert-butylphenyl) phosphite, more preferably 2,6-di-tert-butyl-4-methylphenol;

[0016] And / or, the light stabilizer includes one or more of 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octylbenzophenone, and a polymeric light stabilizer 362 , preferably the polymeric light stabilizer 362 .

[0017] Preferably, the weight proportions of the auxiliary agents are as follows: 0.3-3 parts of crosslinking agent, 0.2-5 parts of plasticizer, 0.5-3 parts of dispersant, 0.2-2 parts of antioxidant and 0.2-2 parts of light stabilizer; more preferably, 0.3-2.5 parts of crosslinking agent, 0.2-3 parts of plasticizer, 0.5-2 parts of dispersant and 0.2-1 parts of antioxidant; most preferably, 0.5-2 parts of crosslinking agent, 0.5-2 parts of plasticizer, 0.5-1 parts of dispersant, 0.3-0.8 parts of antioxidant and 0.3-0.8 parts of light stabilizer.

[0018] Preferably, the preparation method of the modified lignin mainly comprises the following steps:

[0019] (a) adding 40-60 parts by weight of an alkaline solution to a reaction vessel 1, heating the reaction vessel to 50-60° C., adding 10-20 parts by weight of lignin, and stirring the mixture for 1-2 hours to obtain a lignin alkaline solution;

[0020] (b) heating to 70-80° C., adding 1-10 parts by weight of formaldehyde, and stirring for 1-2 hours to obtain a lignin aldehyde solution;

[0021] (c) adding 1-5 parts by weight of ethylenediamine and 2-5 parts by weight of a phosphonic acid compound to the reaction vessel 2, raising the temperature to 70-90° C., and continuing the reaction at this temperature for 0.5-1 hour to obtain an ethylenediamine salt of the phosphonic acid compound;

[0022] (d) adding the lignin aldehyde solution obtained in reactor 1 dropwise into reactor 2, and continuing to keep warm and stir for 2-4 hours;

[0023] (e) vacuum drying at 60-70° C., crushing, and sieving to obtain a modified lignin polymer.

[0024] Preferably, in step (a), the lignin comprises one or more of alkali lignin, organic lignin, and lignin sulfonate;

[0025] Preferably, in step (a), the alkaline solution comprises 5% of one or more of potassium hydroxide, potassium carbonate, and potassium bicarbonate, more preferably potassium hydroxide;

[0026] Preferably, in step (c), the phosphonic acid compound includes one or more of amino trimethylene phosphonic acid, ethylenediaminetetramethylene phosphonic acid, hexamethylenediaminetetramethylene phosphonic acid, polyaminopolyether methylene phosphonic acid, and bis-1,6-hexamethylenetriaminepentamethylphosphonic acid; more preferably, one or more of amino trimethylene phosphonic acid, ethylenediaminetetramethylene phosphonic acid, and hexamethylenediaminetetramethylene phosphonic acid.

[0027] A method for preparing a modified fully biodegradable ground film with fertilizer effect comprises the following steps: fully mixing biodegradable resin, modified lignin, mineral powder and additives, extruding and granulating the particles, and forming the particles by co-extrusion and film blowing.

[0028] Preferably, the method comprises the following steps:

[0029] (1) mixing the biodegradable resin, modified lignin, and additives uniformly, adding the mixture into a co-rotating twin-screw extruder hopper, and extruding and granulating the mixture to obtain a masterbatch;

[0030] (2) The masterbatch is co-extruded into a blown film to obtain the modified fully biodegradable ground film having a fertilizer effect.

[0031] Preferably, in step 1:

[0032] The mixing time is 30 min-1000 min, preferably 80-800 min, more preferably 100-300 min;

[0033] The mixing speed is 30-5000 rpm, preferably 100-3000 rpm, and more preferably 150-2000 rpm;

[0034] The mixing temperature is 20-120°C, preferably 30-110°C, and more preferably 50-100°C;

[0035] The extrusion conditions are as follows: the temperature of zones 1 to 6 is 60-175°C, the die temperature is 120-180°C, and the rotation speed is 30-600rpm; preferably, the temperature of zones 1 to 6 is 80-170°C, the die temperature is 130-175°C, and the rotation speed is 60-500rpm; more preferably, the temperature of zones 1 to 6 is 90-160°C, the die temperature is 160-170°C, and the rotation speed is 200-450rpm.

[0036] Preferably, in step 2, the film blowing bag making temperature is 120-180°C, preferably 130-175°C, and more preferably 140-165°C.

[0037] The reagents and raw materials used in the present invention are commercially available.

[0038] Lignin degrades very slowly and has little effect as a fertilizer during the crop growth period. It can only improve the soil in the later stage. The modified lignin in this scheme is a phosphonic acid compound ethylenediamine salt lignin, which contains nitrogen, phosphorus and potassium required by crops. As a ground film, it acts as a nitrogen, phosphorus and potassium fertilizer during the degradation process, promoting crop growth.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] 1) In the present invention, the two-layer and multiple co-extrusion blown film technology has a simple process route and reduced production costs; the product is green and environmentally friendly, has good stability and biodegradability, and has a good improvement effect on alleviating white pollution and improving soil ecological balance.

[0041] 2) In the present invention, the filler lignin is extracted from papermaking waste, which has a wide source and low price, reducing product cost. After modification, it has excellent mechanical properties and is easy to process and synthesize, thereby achieving efficient utilization of resources.

[0042] 3) The product prepared by the present invention has low light transmittance and can effectively control weeds without the need to add additional masterbatch, thereby increasing the effective use period of the mulch film and effectively reducing the amount of pesticide used.

[0043] 4) The modified lignin of the present invention is added as a filler to the mulch film formula. After the mulch film is degraded, it can increase the nitrogen, phosphorus and potassium fertility of the soil, continuously ensure crop growth, increase crop yield, and also have a good effect on protecting the environment and soil quality. DETAILED DESCRIPTION

[0044] The present invention is further illustrated by way of examples below, but the present invention is not limited to the scope of the examples. Experimental methods in the following examples where specific conditions are not specified were performed according to conventional methods and conditions, or selected according to the product specifications.

[0045] On the basis of conforming to the common sense in this field, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0046] Example 1

[0047] A modified fully biodegradable mulch film with fertilizer effect, the types and amounts of the components in its raw materials are shown in Table 1.

[0048] Table 1 Raw material composition of the modified fully biodegradable mulch film described in Example 1

[0049] Raw material composition Specific types Weight parts / parts Biodegradable resin PBAT / PLA 80 / 4 Filling Modified lignin / calcium carbonate 13 / 3 plasticizers DOP 0.8 crosslinking agent ADR / BIBP 0.25 / 0.25 antioxidants 2,6-di-tert-butyl-4-methylphenol 0.5 Light stabilizers Polymeric light stabilizer 362 0.3 dispersants Erucamide / Stearic Acid 0.4 / 0.3

[0050] The preparation method of the modified lignin mainly comprises the following steps:

[0051] (a) adding 50 parts by weight of a 5% potassium hydroxide solution to a reaction vessel 1, heating the vessel to 60° C., adding 20 parts by weight of alkali lignin, and stirring the mixture for 2 h to obtain an alkaline lignin solution;

[0052] (b) heating to 80° C., adding 5 parts by weight of formaldehyde, and stirring for 2 h to obtain a lignin aldehyde solution;

[0053] (c) adding 5 parts by weight of ethylenediamine and 5 parts by weight of aminotri(methylenephosphonic acid) to the reaction vessel 2, raising the temperature to 90° C., and continuing the reaction at this temperature for 1 hour to obtain the phosphonic acid compound ethylenediamine salt;

[0054] (d) adding the lignin aldehyde solution obtained in reactor 1 dropwise into reactor 2, and continuing to keep warm and stir for 3 h;

[0055] (e) vacuum drying at 70° C., crushing, and sieving to obtain a modified lignin polymer.

[0056] A method for preparing a modified fully biodegradable mulch film having a fertilizer effect comprises the following steps:

[0057] (1) adding the raw material composition into a high-speed blender and mixing at a mixing temperature of 95° C., a mixing speed of 170 rpm, and a mixing time of 300 min to obtain a primary mixture 1; then placing the primary mixture 1 into a twin-screw extruder for extrusion, plasticization, and granulation to obtain a masterbatch; the temperatures of the twin-screw extruder from zone 1 to zone 6 are 90° C., 125° C., 160° C., 165° C., 168° C., and 168° C., respectively; the head temperature of the twin-screw extruder is 168° C., and the screw speed is 250 rpm;

[0058] (2) The masterbatch prepared above was placed into a co-extrusion film blowing machine for film blowing molding at a temperature of 162° C. to obtain the modified fully biodegradable ground film (thickness 0.010 mm) having a fertilizer effect.

[0059] Example 2

[0060] A modified fully biodegradable mulch film with fertilizer effect, the types and amounts of the components in its raw materials are shown in Table 2.

[0061] Table 2 Raw material composition of the modified fully biodegradable mulch film described in Example 2

[0062]

[0063] The preparation method of the modified lignin mainly comprises the following steps:

[0064] (a) adding 60 parts by weight of a 5% potassium carbonate solution to a reactor 1, heating the reactor to 60° C., adding 20 parts by weight of lignin sulfonate, and stirring the reactor for 2 h to obtain a lignin alkaline solution;

[0065] (b) heating to 70-80° C., adding 8 parts by weight of formaldehyde, and stirring for 2 hours to obtain a lignin aldehyde solution;

[0066] (c) adding 5 parts by weight of ethylenediamine and 5 parts by weight of ethylenediaminetetramethylenephosphonic acid to the reaction vessel 2, raising the temperature to 90° C., and continuing the reaction at this temperature for 1 hour to obtain the phosphonic acid compound ethylenediamine salt;

[0067] (d) adding the lignin aldehyde solution obtained in reactor 1 dropwise into reactor 2, and continuing to keep warm and stir for 2 h;

[0068] (e) vacuum drying at 70° C., crushing, and sieving to obtain a modified lignin polymer.

[0069] A method for preparing a modified fully biodegradable mulch film having a fertilizer effect comprises the following steps:

[0070] (2) adding the raw material composition into a high-speed blender and mixing at a mixing temperature of 80° C., a mixing speed of 180 rpm, and a mixing time of 200 min to obtain a primary mixture 1; then placing the primary mixture 1 into a twin-screw extruder for extrusion, plasticization, and granulation to obtain a masterbatch; the temperatures of the twin-screw extruder from zone 1 to zone 6 are 90° C., 115° C., 150° C., 160° C., 165° C., and 165° C., respectively; the head temperature of the twin-screw extruder is 165° C., and the screw speed is 300 rpm;

[0071] (2) The masterbatch prepared above was placed into a co-extrusion film blowing machine for film blowing molding at a temperature of 150° C. to obtain the modified fully biodegradable ground film (thickness 0.010 mm) having a fertilizer effect.

[0072] Example 3

[0073] A modified fully biodegradable mulch film with fertilizer effect, the types and amounts of the components in its raw materials are shown in Table 3.

[0074] Table 3 Raw material composition of the modified fully biodegradable mulch film described in Example 3

[0075] Raw material composition Specific types Weight parts / parts Biodegradable resin PBAT / PLA 76 / 4 Filling Modified lignin / talc 12 / 8 plasticizers TBC 1 crosslinking agent BIBP 0.3 antioxidants 2,6-di-tert-butyl-4-methylphenol 0.5 Light stabilizers Polymeric light stabilizer 362 0.4 dispersants stearic acid 0.6

[0076] The preparation method of the modified lignin mainly comprises the following steps:

[0077] (a) adding 60 parts by weight of a 5% potassium hydroxide solution to a reaction vessel 1, heating the vessel to 60° C., adding 20 parts by weight of lignin sulfonate, and stirring the mixture for 2 h to obtain a lignin alkaline solution;

[0078] (b) heating to 70-80° C., adding 8 parts by weight of formaldehyde, and stirring for 2 hours to obtain a lignin aldehyde solution;

[0079] (c) adding 5 parts by weight of ethylenediamine and 5 parts by weight of a phosphonic acid compound (aminotrimethylphosphonic acid: hexamethylenediaminetetramethylphosphonic acid ratio of 4:1) to reaction kettle 2, raising the temperature to 90° C., and continuing the reaction at this temperature for 1 hour to obtain an ethylenediamine salt of the phosphonic acid compound;

[0080] (d) adding the lignin aldehyde solution obtained in reactor 1 dropwise into reactor 2, and continuing to keep warm and stir for 2 h;

[0081] (e) vacuum drying at 70° C., crushing, and sieving to obtain a modified lignin polymer.

[0082] A method for preparing a modified fully biodegradable mulch film having a fertilizer effect comprises the following steps:

[0083] (1) The raw material composition is added to a high-speed blender and mixed at a mixing temperature of 60° C., a mixing speed of 100 rpm, and a mixing time of 380 min to obtain a primary mixture 1; the primary mixture 1 is then placed in a twin-screw extruder for extrusion, plasticization, and granulation to obtain a masterbatch; the temperatures of the twin-screw extruder from zone 1 to zone 6 are 80° C., 130° C., 150° C., 165° C., 166° C., and 169° C., respectively; the head temperature of the twin-screw extruder is 170° C., and the screw speed is 220 rpm.

[0084] (2) The masterbatch prepared above was placed into a co-extrusion film blowing machine for film blowing molding at a temperature of 158° C. to obtain the modified fully biodegradable ground film (thickness 0.010 mm) having a fertilizer effect.

[0085] Comparative Example 1

[0086] A fully biodegradable ground film, the types and amounts of the components in its raw materials are shown in Table 4.

[0087] A method for preparing a fully biodegradable ground film comprises the following steps:

[0088] (1) adding the raw material composition into a high-speed blender and mixing at a mixing temperature of 110° C., a mixing speed of 120 rpm, and a mixing time of 90 min to obtain a primary mixture 1; then placing the primary mixture 1 into a twin-screw extruder for extrusion, plasticization, and granulation to obtain a masterbatch; the temperatures of the twin-screw extruder from zone 1 to zone 6 are 100° C., 135° C., 155° C., 165° C., 168° C., and 168° C., respectively; the head temperature of the twin-screw extruder is 168° C., and the screw speed is 350 rpm;

[0089] (2) The masterbatch prepared above was placed into a co-extrusion film blowing machine for film blowing molding at a temperature of 160° C. to obtain the fully biodegradable ground film (thickness 0.010 mm).

[0090] Table 4 Raw material composition of the fully biodegradable mulch film described in Comparative Example 1

[0091]

[0092]

[0093] Comparative Example 2

[0094] A fully biodegradable mulch film, the types and amounts of the components in its raw materials are shown in Table 5.

[0095] A method for preparing a fully biodegradable ground film comprises the following steps:

[0096] (1) adding the raw material composition into a high-speed blender and mixing at a mixing temperature of 100° C., a mixing speed of 100 rpm, and a mixing time of 100 min to obtain a primary mixture 1; then placing the primary mixture 1 into a twin-screw extruder for extrusion, plasticization, and granulation to obtain a masterbatch; the temperatures of the twin-screw extruder from zone 1 to zone 6 are 90° C., 135° C., 160° C., 165° C., 170° C., and 170° C., respectively; the head temperature of the twin-screw extruder is 170° C., and the screw speed is 220 rpm;

[0097] (2) The masterbatch prepared above was placed into a co-extrusion film blowing machine for film blowing molding at a temperature of 165° C. to obtain the fully biodegradable ground film (thickness 0.010 mm).

[0098] Table 5 Raw material composition of the fully biodegradable mulch film described in Comparative Example 2

[0099] Raw material composition Specific types Weight parts / parts Biodegradable resin PBAT / PLA 85 / 5 Filling talcum powder 10 plasticizers ATBC 0.7 crosslinking agent ADR / BIBP 0.3 / 0.2 antioxidants 2,6-di-tert-butyl-4-methylphenol 0.5 Light stabilizers Polymeric light stabilizer 362 0.4 dispersants Erucamide / Stearic Acid 0.4 / 0.2

[0100] Implementation Effect

[0101] According to the method in the national standard GB / T6673, the ground films formulated in Examples 1-3 and Comparative Examples 1-2 were made into test specimens, and the tensile strength and elongation at break of the above examples and comparative examples were tested. The specific data are shown in Table 6.

[0102] Table 6 Ground film performance test

[0103]

[0104] The ground films formulated in Examples 1-3 and Comparative Examples 1-2 were mechanically mulched and then planted with spring peanuts. The data on the number of weeds during their growth and the peanut yield after harvest are shown in Table 7.

[0105] Table 7 Survey on weeds and yield in the experimental plots

[0106]

[0107] All treatments had the same water and fertilizer management level. In the late growth period of peanuts, a 5-point sampling method was used for each treatment to measure the content of total nitrogen, available phosphorus, and available potassium in soil samples at 0-20 cm. The specific data are shown in Table 8.

[0108] Table 8 Soil fertility determination

[0109]

[0110] The results show that the modified fully biodegradable mulch film with fertilizer effect has better mechanical properties, effectively controls weeds, reduces pesticide residues, and at the same time can improve soil fertility, promote peanut growth and development, thereby increasing yield, and can better meet the use requirements.

[0111] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A modified fully biodegradable mulch film with fertilizer function, characterized in that: The raw material comprises the following components in parts by weight: 60-100 parts of biodegradable resin, 5-30 parts of modified lignin, 0-10 parts of mineral powder, and 2-15 parts of additives; Wherein, the auxiliary agents include crosslinking agents, plasticizers, dispersants, antioxidants and light stabilizers; The modified lignin is phosphonic acid compound ethylenediamine salt lignin, and the preparation method of the modified lignin comprises the following steps: (a) adding 40-60 parts by weight of an alkaline solution to a reaction vessel 1, heating the reaction vessel to 50-60° C., adding 10-20 parts by weight of lignin, and stirring the mixture for 1-2 hours to obtain a lignin alkaline solution; (b) heating to 70-80° C., adding 1-10 parts by weight of formaldehyde, and stirring for 1-2 hours to obtain a lignin aldehyde solution; (c) adding 1-5 parts by weight of ethylenediamine and 2-5 parts by weight of a phosphonic acid compound to the reactor 2, raising the temperature to 70-90° C., and continuing the reaction at this temperature for 0.5-1 hour to obtain an ethylenediamine salt of a phosphonic acid compound, wherein the phosphonic acid compound comprises one or more of aminotrimethylphosphonic acid, ethylenediaminetetramethylphosphonic acid, hexamethylenediaminetetramethylphosphonic acid, polyaminopolyether-methylenephosphonic acid, and bis-1,6-hexamethylenetriaminepentamethylphosphonic acid; (d) adding the lignin aldehyde solution obtained in reactor 1 dropwise into reactor 2, and continuing to keep warm and stir for 2-4 hours; (e) vacuum drying at 60-70° C., crushing, and sieving to obtain a modified lignin polymer.

2. The modified fully biodegradable mulch film with fertilizer function according to claim 1, characterized in that: The biodegradable resin is mainly poly(butylene adipate / terephthalate) and / or poly(lactic acid).

3. The modified fully biodegradable mulch film with fertilizer function according to claim 1, characterized in that: The mineral powder includes talc and / or calcium carbonate.

4. The modified fully biodegradable ground film with fertilizer function according to claim 1, characterized in that: The cross-linking agent includes one or more of 1,4-bis-tert-butyl peroxide isopropylbenzene (BIBP), dibenzoyl peroxide (BPO) and German BASF-ADR-4370S (ADR); And / or, the plasticizer includes one or more of tributyl citrate (TBC), acetyl tri-n-butyl citrate (ATBC), dioctyl phthalate (DOP), and xylitol; and / or, the dispersant comprises one or more of stearic acid, erucamide, and ethylene bisstearamide; And / or, the antioxidant includes one or more of 2,6-di-tert-butyl-4-methylphenol and tris(2,4-di-tert-butylphenyl) phosphite; And / or, the light stabilizer includes one or more of 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octylbenzophenone, and a polymeric light stabilizer 362 .

5. The modified fully biodegradable ground film with fertilizer function according to claim 4, characterized in that: The weight proportions of the auxiliary agents are as follows: 0.3-3 parts of a crosslinking agent, 0.2-5 parts of a plasticizer, 0.5-3 parts of a dispersant, 0.2-2 parts of an antioxidant and 0.2-2 parts of a light stabilizer.

6. The modified fully biodegradable mulch film with fertilizer function according to claim 1, characterized in that: In the step (a), the lignin comprises one or more of alkali lignin, organic lignin, and lignin sulfonate; In the step (a), the alkaline solution includes 5% of one or more of potassium hydroxide, potassium carbonate, and potassium bicarbonate.

7. The method for preparing a modified fully biodegradable mulch film having a fertilizer effect according to any one of claims 1 to 6, characterized in that: The film is made of biodegradable resin, modified lignin, mineral powder and additives. After the components are fully mixed, they are extruded into granules, and the granules are co-extruded and blown into film.

8. The method for preparing a modified fully biodegradable mulch film having a fertilizer effect according to claim 7, characterized in that: The steps include: (1) mixing the biodegradable resin, modified lignin, and additives uniformly, adding the mixture into a co-rotating twin-screw extruder hopper, and extruding and granulating the mixture to obtain a masterbatch; (2) The masterbatch is co-extruded into a blown film to obtain the modified fully biodegradable ground film having a fertilizer effect.

9. The method for preparing a modified fully biodegradable mulch film having a fertilizer effect according to claim 8, characterized in that: In step 1, the mixing time is 30 min-1000 min, the mixing speed is 30-5000 rpm, the mixing temperature is 20-120° C., and the extrusion conditions are: the temperature of zones 1 to 6 is 60-175° C., the die temperature is 120-180° C., and the speed is 30-600 rpm. In the step 2, the film blowing bag making temperature is 120-180°C.

Images