CN116376242A - A modified fully biodegradable mulch film with fertilizer effect and its preparation method - Google Patents

Abstract

The modified full-biodegradable mulch film with the fertilizer effect is characterized by comprising the following raw materials 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 auxiliary agent; wherein the modified lignin is phosphonic acid compound ethylenediamine salt lignin. And mixing the raw materials, extruding, granulating, and performing coextrusion film blowing molding on the particles to obtain the modified full-biodegradable mulch film with the fertilizer effect. The modified full-biodegradable mulching film with fertilizer effect prepared by the method has the following advantages: the lignin with wide sources, low price and easy availability is added, so that the high-efficiency utilization of resources is realized; the modified mulching film has the advantages of good toughness, good tensile property and the like, also has good degradation property, can increase the nitrogen, phosphorus and potassium fertility of soil after degradation, and has good effect on protecting the environment and the soil quality.

Description

A modified fully biodegradable plastic film with fertilizer function and preparation method thereof

technical field

The invention belongs to the field of degradable composite materials, and in particular relates to a modified fully biodegradable plastic film with fertilizer function and a preparation method thereof.

Background technique

Film-covered planting has the functions of increasing temperature and moisture, resisting drought and saving water, and suppressing weeds. However, traditional agricultural polyethylene film does not degrade. The thickness of PE film in the market is mostly off-surface products with a thickness of less than 10 μm. It is very difficult to recycle, resulting in a large amount of farmland. White pollution and residual film seriously affect the decomposition of humus and the air and water permeability of the soil, resulting in the destruction of the soil structure and extremely adverse effects on the environment and agricultural production.

Promoting fully biodegradable mulch to replace traditional PE mulch is a new trend to solve white pollution in farmland. At present, many areas have begun to research and promote degradable plastic film, but the following problems still exist in the degradable plastic film: 1. The raw material is expensive and the cost is high; 2. The performance of the fully biodegradable plastic film is poor, and mechanical coating and plowing cannot meet the use requirements; 3. Lifespan The cycle is short and the degradation period is uncontrollable.

Therefore, there is an urgent need in this field to develop a fully biodegradable mulch film with a wide range of raw materials, low prices, and environmental protection to achieve efficient utilization of resources, and the product has excellent mechanical properties and is easy to process and synthesize, which can meet the needs of heat preservation and moisture conservation during the growth period of crops , It can be used as fertilizer in the later stage of plastic film degradation process to continuously ensure crop growth and increase crop yield.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the problems in the prior art that the fully biodegradable film retaining moisture and fertilizer is difficult to meet the use requirements, and the degradation period is uncontrollable, poor in performance and high in cost.

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

A modified fully biodegradable mulch film with a fertilizer effect, 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, 2 -15 auxiliary agents;

Wherein, the modified lignin is a phosphonic acid compound ethylenediamine salt lignin.

Preferably, the biodegradable resin comprises polybutylene adipate/terephthalate (PBAT) and/or polylactic acid (PLA).

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

Preferably, the auxiliary agents include crosslinking agents, plasticizers, dispersants, antioxidants and light stabilizers.

Preferably, the crosslinking agent includes one or the other of 1,4-bis-tert-butylperoxycumene (BIBP), dibenzoyl peroxide (BPO) and German BASF ADR-4370S (ADR) Various, more preferably BIBP and/or ADR;

And/or, described plasticizer comprises one or more in tributyl citrate (TBC), acetyl tri-n-butyl citrate (ATBC), dioctyl phthalate (DOP), xylitol Kind, more preferably one or more in ATBC, TBC and DOP;

And/or, the dispersant includes one or more of stearic acid, erucamide, and ethylene bisstearamide, more preferably stearic acid and/or erucamide;

And/or, the antioxidant includes one or more of 2,6-di-tert-butyl-4-methylphenol, tris(2,4-di-tert-butylphenyl) phosphite, and more Preferably it is 2,6-di-tert-butyl-4-methylphenol;

And/or, the light stabilizer includes one or more of 2-hydroxyl-4-methoxybenzophenone, 2-hydroxyl-4-n-octylbenzophenone, polymeric light stabilizer 362 species, more preferably polymeric light stabilizer 362.

Preferably, the parts by weight of the auxiliary agent 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 cross-linking agent, 0.2-3 parts of plasticizer, 0.5-2 parts of dispersant, 0.2-1 part of antioxidant; optimally 0.5-2 parts of cross-linking agent, 0.5-2 parts of plasticizer, 0.5-1 part of dispersant, 0.3-0.8 part of antioxidant, 0.3-0.8 part of light stabilizer.

Preferably, the preparation method of described modified lignin mainly comprises the following steps:

(a) Add 40-60 parts by weight of an alkaline solution to the reaction kettle 1, heat up to 50-60° C., add 10-20 parts by weight of lignin, and stir for 1-2 hours to obtain a lignin alkali solution;

(b) heating up 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) Add 1-5 parts by weight of ethylenediamine and 2-5 parts by weight of phosphonic acid compound into the reaction kettle 2, raise the temperature to 70-90°C, and continue the heat preservation reaction for 0.5-1h to obtain the phosphonic acid compound ethylenediamine Salt;

(d) drip into the reaction kettle 2 the lignin aldehyde solution obtained in the reaction kettle 1, and continue to insulate and stir for 2-4h;

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

Preferably, in the step (a), the lignin includes one or more of alkali lignin, organic lignin, and lignosulfonate;

Preferably, in the step (a), the alkaline solution includes one or more of 5% potassium hydroxide, potassium carbonate, potassium bicarbonate, more preferably potassium hydroxide;

Preferably, in the step (c), the phosphonic acid compound includes amino trimethylene phosphonic acid, ethylenediamine tetramethylene phosphonic acid, hexamethylenediamine tetramethylene phosphonic acid, polyaminopolyether group methylene phosphonic acid One or more of bis-1,6-hexamethylenetriaminepentamethylphosphonic acid; more preferably aminotrimethylenephosphonic acid, ethylenediaminetetramethylenephosphonic acid, hexamethylenediaminetetramethylenephosphonic acid One or more of acids.

A method for preparing a modified fully biodegradable mulch film with the function of fertilizer, which consists of biodegradable resin, modified lignin, mineral powder, and additives, after fully mixing each component, extruding and granulating, and the particles are co-extruded Blown film molding.

Preferably, the following steps are included:

(1) Mix the biodegradable resin, modified lignin, auxiliary agent, uniformly, add co-rotating twin-screw extruder silo, extrude and granulate to obtain masterbatch;

(2) The above-mentioned masterbatch is molded by co-extrusion blown film to obtain the modified fully biodegradable mulch film with fertilizer effect.

Preferably, in the step 1:

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

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

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

The extrusion conditions are as follows: the temperature from zone 1 to zone 6 is 60-175°C, the temperature of the machine head is 120-180°C, and the rotation speed is 30-600rpm; preferably, the temperature from zone 1 to zone 6 is 80-170°C, and the temperature of the machine head is 130°C. -175°C, rotation speed 60-500rpm; more preferably, the temperature of the first zone to the sixth zone is 90-160°C, the temperature of the machine head is 160-170°C, and the rotation speed is 200-450rpm.

Preferably, in the step 2, the temperature of the blown film bag making is 120-180°C, more preferably 130-175°C, more preferably 140-165°C.

The reagents and raw materials used in the present invention are all commercially available.

The degradation of lignin is very slow, and it has little effect as a fertilizer during the growth period of crops, and the soil can be improved in the later stage. The modified lignin of this scheme is phosphonic acid compound ethylenediamine salt lignin, which contains nitrogen, phosphorus, and potassium needed by crops. The plastic film acts as a nitrogen, phosphorus and potassium fertilizer during the degradation process to promote crop growth.

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

1) In the present invention, with the 2-layer and multiple co-extrusion blown film technology, the process route is simple, and the production cost is reduced; the product is green and environmentally friendly, has good stability and biodegradability, and has a great effect on alleviating white pollution and soil ecological balance. Good improvement.

2) In the present invention, the filler lignin is extracted from papermaking waste, which has a wide range of sources, low price, reduced product cost, excellent mechanical properties after modification, easy processing and synthesis, and efficient utilization of resources.

3) The product obtained by the present invention has low film light transmittance, and can effectively control weeds without adding additional color masterbatch, increase the effective life cycle of the mulch film, and effectively reduce the use of pesticides.

4) The modified lignin of the present invention is used as a filler and added to the mulch formula. After the mulch is degraded, soil nitrogen, phosphorus, and potassium fertility can be increased, crop growth can be continuously ensured, crop yield can be increased, and the protection of the environment and soil quality is also very good. effect.

Detailed ways

The present invention is further illustrated below by means of examples, but the present invention is not limited to the scope of the examples. For the experimental methods that do not specify specific conditions in the following examples, select according to conventional methods and conditions, or according to the product instructions.

On the basis of conforming to common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain preferred examples of the present invention.

Example 1

A kind of modified fully biodegradable mulch film with fertilizer function, the types and dosage of each component in its raw materials are shown in Table 1.

The raw material composition of modified fully biodegradable mulch film described in Table 1 embodiment 1

Raw material composition specific type parts by weight/part biodegradable resin PBAT/PLA 80/4 filler Modified Lignin/Calcium Carbonate 13/3 plasticizer DOP 0.8 crosslinking agent ADR/BIBP 0.25/0.25 antioxidant 2,6-di-tert-butyl-4-methylphenol 0.5 light stabilizer Polymeric Light Stabilizer 362 0.3 Dispersant Erucamide/Stearic Acid 0.4/0.3

Wherein the preparation method of modified lignin mainly comprises the following steps:

(a) Add 50 parts by weight of a 5% potassium hydroxide solution to the reactor 1, heat up to 60° C., add 20 parts by weight of alkali lignin, and stir for 2 hours to obtain a lignin alkali solution;

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

(c) Add 5 parts by weight of ethylenediamine and 5 parts by weight of aminotrimethylene phosphonic acid into the reaction kettle 2, heat up to 90° C., and continue the heat preservation reaction for 1 hour to obtain ethylenediamine salt of the phosphonic acid compound;

(d) drip into the lignin aldehyde solution obtained in the reactor 1 in the reactor 2, and continue to insulate and stir for 3 hours;

(e) Vacuum drying at 70° C., crushing, and sieving to obtain a modified lignin polymer.

A method for preparing a modified fully biodegradable mulch film with a fertilizer effect, comprising the steps of:

(1) Add the raw material composition into a high-speed blender and mix, the mixing temperature is 95°C, the mixing speed is 170rpm, and the mixing time is 300min to obtain the primary mixture 1; Extrude, plasticize and granulate in the screw extruder to obtain masterbatch; the temperature of the twin-screw extruder from the first zone to the sixth zone is 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 rotating speed of the screw is 250rpm;

(2) Put the above-mentioned prepared masterbatch into a co-extrusion film blowing machine for blown film forming, the temperature of blown film forming is 162°C, and the modified fully biodegradable mulch film (thickness) with fertilizer effect is obtained 0.010mm).

Example 2

A modified fully biodegradable mulch film with a fertilizer effect, the types and amounts of each component in its raw materials are shown in Table 2.

The raw material composition of modified fully biodegradable mulch film described in table 2 embodiment 2

Wherein the preparation method of modified lignin mainly comprises the following steps:

(a) Add 60 parts by weight of a 5% potassium carbonate solution to the reactor 1, heat up to 60° C., add 20 parts by weight of lignosulfonate, and stir for 2 hours to obtain a lignin alkali solution;

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

(c) Add 5 parts by weight of ethylenediamine and 5 parts by weight of ethylenediamine tetramethylene phosphonic acid into the reaction kettle 2, heat up to 90° C., and continue the heat preservation reaction for 1 hour to obtain the ethylenediamine salt of the phosphonic acid compound;

(d) drip into the lignin aldehyde solution obtained in the reactor 1 in the reactor 2, and continue to insulate and stir for 2 hours;

(e) Vacuum drying at 70° C., crushing, and sieving to obtain a modified lignin polymer.

A method for preparing a modified fully biodegradable mulch film with a fertilizer effect, comprising the steps of:

(2) Add the raw material composition into a high-speed blender and mix, the mixing temperature is 80°C, the mixing speed is 180rpm, and the mixing time is 200min to obtain the primary mixture 1; Extrude, plasticize and granulate in the screw extruder to obtain masterbatch; the temperature of the twin-screw extruder from the first zone to the sixth zone is 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 rotating speed of the screw is 300rpm;

(2) Put the above-mentioned prepared masterbatch into a co-extrusion film blowing machine for blown film forming, the temperature of blown film forming is 150°C, and the modified fully biodegradable mulch film (thickness) with fertilizer effect is obtained 0.010mm).

Example 3

A modified fully biodegradable mulch film with a fertilizer effect, the types and amounts of each component in its raw materials are shown in Table 3.

The raw material composition of modified fully biodegradable mulch film described in table 3 embodiment 3

Raw material composition specific type parts by weight/part biodegradable resin PBAT/PLA 76/4 filler Modified Lignin/Talc 12/8 plasticizer TBC 1 crosslinking agent BIBP 0.3 antioxidant 2,6-di-tert-butyl-4-methylphenol 0.5 light stabilizer Polymeric Light Stabilizer 362 0.4 Dispersant stearic acid 0.6

Wherein the preparation method of modified lignin mainly comprises the following steps:

(a) Add 60 parts by weight of a 5% potassium hydroxide solution to the reaction kettle 1, heat up to 60° C., add 20 parts by weight of lignosulfonate, and stir for 2 hours to obtain a lignin alkali solution;

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

(c) Add 5 parts by weight of ethylenediamine and 5 parts by weight of phosphonic acid compound (aminotrimethylene phosphonic acid: hexamethylene diamine tetramethylene phosphonic acid ratio 4:1) into the reactor 2, heat up to 90°C, Continue the insulation reaction for 1h to obtain the phosphonic acid compound ethylenediamine salt;

(d) drip into the lignin aldehyde solution obtained in the reactor 1 in the reactor 2, and continue to insulate and stir for 2 hours;

(e) Vacuum drying at 70° C., crushing, and sieving to obtain a modified lignin polymer.

A method for preparing a modified fully biodegradable mulch film with a fertilizer effect, comprising the steps of:

(1) Add the raw material composition into a high-speed blender and mix it. The mixing temperature is 60° C., the mixing speed is 100 rpm, and the mixing time is 380 minutes to obtain the primary mixture 1; Extrude, plasticize and granulate in the screw extruder to obtain masterbatch; the temperature of the twin-screw extruder from the first zone to the sixth zone is 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.

(2) Put the above-mentioned prepared masterbatch into a co-extrusion film blowing machine for blown film forming, the temperature of blown film forming is 158°C, and the modified fully biodegradable mulch film (thickness) with fertilizer effect is obtained 0.010mm).

Comparative example 1

A fully biodegradable mulch film, the types and amounts of each component in its raw materials are shown in Table 4.

A method for preparing a fully biodegradable mulch film, comprising the steps of:

(1) Add the raw material composition into a high-speed blender and mix it. The mixing temperature is 110° C., the mixing speed is 120 rpm, and the mixing time is 90 minutes to obtain the primary mixture 1; Extrude, plasticize and granulate in the screw extruder to obtain masterbatch; the temperature of the twin-screw extruder from the first zone to the sixth zone is 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 350rpm;

(2) Put the masterbatch prepared above into a co-extrusion blown film machine for blown film forming, the temperature of the blown film forming is 160°C, and the above-mentioned fully biodegradable mulch film (thickness 0.010mm) is obtained.

The raw material composition of the fully biodegradable mulch film described in Table 4 Comparative Example 1

Comparative example 2

A fully biodegradable mulch film, the types and amounts of each component in its raw materials are shown in Table 5.

A method for preparing a fully biodegradable mulch film, comprising the steps of:

(1) Add the raw material composition into a high-speed blender and mix, the mixing temperature is 100°C, the mixing speed is 100rpm, and the mixing time is 100min to obtain the primary mixture 1; Extrude, plasticize and granulate in the screw extruder to obtain masterbatch; the temperature of the twin-screw extruder from the first zone to the sixth zone is 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 220rpm;

(2) Put the masterbatch prepared above into a co-extrusion blown film machine for blown film forming, the temperature of blown film forming is 165° C., to obtain the fully biodegradable mulch film (thickness 0.010mm).

The raw material composition of the fully biodegradable mulch film described in Table 5 Comparative Example 2

Raw material composition specific type parts by weight/part biodegradable resin PBAT/PLA 85/5 filler talcum powder 10 plasticizer ATBC 0.7 crosslinking agent ADR/BIBP 0.3/0.2 antioxidant 2,6-di-tert-butyl-4-methylphenol 0.5 light stabilizer Polymeric Light Stabilizer 362 0.4 Dispersant Erucamide/Stearic Acid 0.4/0.2

Implementation Effect

According to the method in the national standard GB/T6673, the mulch film of the formula in the embodiment 1-3 and the comparative example 1-2 is made into the specimen to be tested, and then detect the tensile strength and the elongation at break of the above-mentioned embodiment and the comparative example, The specific data are shown in Table 6.

Table 6 Film Performance Test

The mulch films formulated in Examples 1-3 and Comparative Examples 1-2 were mechanically mulched, and then spring-sowed peanuts were planted. The data on the number of weeds during growth and the yield of peanuts after harvest are shown in Table 7.

Table 7 Investigation of weeds and yield in experimental plots

All treatments have uniform water and fertilizer management levels. At the later stage of peanut growth, each treatment adopts the 5-point sampling method to measure the contents of total nitrogen, available phosphorus and available potassium in soil samples of 0-20 cm in size. The specific data are shown in Table 8.

Table 8 Determination of soil fertility

It can be seen from the results that the modified fully biodegradable mulch film with the effect of fertilizer has better mechanical properties, effectively controls weeds, reduces pesticide residues, improves soil fertility, promotes peanut growth and development, and then increases yield. Better meet the requirements of use.

The basic principles, main features and advantages of the present invention have been shown and described above. Those skilled in the industry should understand that the present invention is not limited by the above-mentioned embodiments. What are described in the above-mentioned embodiments and the description only illustrate the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will also have Variations and improvements are possible, which fall within the scope of the claimed invention. The scope of the claimed invention is defined by the appended claims and their equivalents.

Claims (10)

1. The modified full-biodegradable mulch film with the fertilizer effect is characterized by comprising the following raw materials 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 auxiliary agent;

wherein the modified lignin is phosphonic acid compound ethylenediamine salt lignin.

2. A modified fully biodegradable mulch film according to claim 1, wherein the biodegradable resin is mainly poly adipic acid/butylene terephthalate and/or poly lactic acid.

3. A modified fully biodegradable mulch film according to claim 1, wherein the mineral powder comprises talc and/or calcium carbonate.

4. The modified fully biodegradable mulch film with fertilizer effect according to claim 1, wherein the auxiliary agent comprises a cross-linking agent, a plasticizer, a dispersing agent, an antioxidant and a light stabilizer;

wherein the cross-linking agent comprises one or more of 1, 4-bis-tert-butylperoxyisopropyl benzene (BIBP), dibenzoyl peroxide (BPO) and German BASF-ADR-4370S (ADR);

and/or the plasticizer comprises one or more of tributyl citrate (TBC), acetyl tri-n-butyl citrate (ATBC), dioctyl phthalate (DOP), xylitol;

and/or the dispersing agent comprises one or more of stearic acid, erucamide and ethylene bis-stearamide;

and/or the antioxidant comprises one or more of 2, 6-di-tert-butyl-4-methylphenol and tri (2, 4-di-tert-butylphenyl) phosphite;

and/or the light stabilizer comprises one or more of 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octylbenzophenone, and polymeric light stabilizer 362.

5. The modified full-biodegradable mulch film with fertilizer effect according to claim 4, wherein the auxiliary agent comprises the following components in parts by weight: 0.3-3 parts of cross-linking agent, 0.2-5 parts of plasticizer, 0.5-3 parts of dispersing agent, 0.2-2 parts of antioxidant and 0.2-2 parts of light stabilizer.

6. The modified fully biodegradable mulch film with fertilizer effect according to claim 1, wherein the preparation method of the modified lignin comprises the following steps:

(a) Adding 40-60 parts by weight of alkaline solution into a reaction kettle 1, heating to 50-60 ℃, adding 10-20 parts by weight of lignin, and stirring for 1-2 hours to obtain lignin alkali solution;

(b) Heating to 70-80 ℃, adding 1-10 parts by weight of formaldehyde, and stirring for 1-2 hours to obtain lignin aldehyde solution;

(c) Adding 1-5 parts by weight of ethylenediamine and 2-5 parts by weight of phosphonic acid compound into a reaction kettle 2, heating to 70-90 ℃, and continuing to perform heat preservation reaction for 0.5-1h to obtain phosphonic acid compound ethylenediamine salt;

(d) Dripping lignin aldehyde solution obtained from the reaction kettle 1 into the reaction kettle 2, and continuously preserving heat and stirring for 2-4h;

(e) Vacuum drying at 60-70deg.C, pulverizing, and sieving to obtain modified lignin polymer.

7. The method for producing a modified lignin according to claim 6, wherein:

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 comprises one or more of 5% potassium hydroxide, potassium carbonate and potassium bicarbonate;

in the step (c), the phosphonic acid compound comprises one or more of aminotrimethylene phosphonic acid, ethylenediamine tetramethylene phosphonic acid, hexamethylenediamine tetramethylene phosphonic acid, polyamino polyether methylene phosphonic acid and bis 1, 6-hexamethylene triamine pentamethylene phosphonic acid.

8. The method for preparing the modified full-biodegradable mulch film with the fertilizer effect according to any one of claims 1 to 7, wherein the film is formed by fully and uniformly mixing the components of biodegradable resin, modified lignin, mineral powder and auxiliary agents, extruding and granulating, and forming particles by co-extrusion film blowing.

9. The modified full-biodegradable mulch film with fertilizer effect and the preparation method thereof according to claim 8, characterized by comprising the following steps:

(1) Uniformly mixing the biodegradable resin, the modified lignin and the auxiliary agent, adding into a feed bin of a homodromous double-screw extruder, and extruding and granulating to obtain master batch;

(2) And (3) performing coextrusion film blowing molding on the master batch to obtain the modified full-biodegradable mulch film with the fertilizer effect.

10. The modified fully biodegradable mulch film with fertilizer effect according to claim 9 and the preparation method thereof, characterized in that:

in the step 1, the mixing time is 30-1000 min, the mixing rotating speed is 30-5000rpm, the mixing temperature is 20-120 ℃, the extrusion conditions are 60-175 ℃ from one area to six areas, the machine head temperature is 120-180 ℃, and the rotating speed is 30-600rpm;

in the step 2, the temperature of film blowing and bag making is 120-180 ℃.