1. The lignin/PBAT composite material is characterized by being prepared from the following components in percentage by mass:

2. the lignin/PBAT composite material according to claim 1, characterized by being prepared from the following components in percentage by mass:

3. the lignin/PBAT composite material according to claim 1, characterized by being prepared from the following components in percentage by mass:

4. the lignin/PBAT composite material according to claim 1, characterized by being prepared from the following components in percentage by mass:

or the components with the following mass percentages:

5. the lignin/PBAT composite material according to claim 1, wherein the metal coordination bond auxiliary agent is at least one of zinc oxalate, zinc acetate, zinc methacrylate, zinc acetylacetonate, iron oxalate, iron acetate and calcium acetate.

6. The lignin/PBAT composite material according to claim 1, wherein the lignin/SiO is present in the form of a slurry₂In the composite nano-particles, lignin and SiO₂The mass ratio of (A) to (B) is 90: 10-70: 30.

7. The lignin/PBAT composite material according to claim 1, wherein the lignin/SiO is present in the form of a slurry₂The preparation method of the composite nano-particles comprises the following steps: performing ultrasonic pre-dispersion on nano silicon dioxide in an ethanol/water mixed system, adding lignin under an alkaline condition, adding acid under a stirring condition to adjust the pH value to 2-7, performing coprecipitation reaction, aging at 20-100 ℃ for 0.5-4 h, performing centrifugal filtration, washing precipitates, and drying by adopting an infrared drying method, or drying a sample by adopting a spray drying method after aging to finally prepare composite nano particles;

the lignin and the nano SiO₂The mass ratio of (A) to (B) is 90: 10-70: 30.

8. the lignin/PBAT composite material according to claim 1 or 7, wherein the lignin is at least one of alkali lignin obtained from alkali pulping in paper industry, enzymatic lignin extracted from ethanol produced by fermentation of lignocellulose, and organosolv lignin extracted from lignocellulose by organosolv method;

the antioxidant is at least one of butyl hydroxy anisole, dibutyl hydroxy toluene, tetra [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid ] pentaerythritol ester, tert-butyl p-diphenol, phenyl diisodecyl phosphite, pentaerythritol diphosphite and methyl 3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate;

the plasticizer is at least one of glycerol triacetate, epoxidized soybean oil, acetyl tri-n-butyl citrate, triethyl citrate and tributyl citrate;

the micron cellulose is micron cellulose obtained by alkaline pulping; the nano-cellulose is at least one of cellulose nano-fibrils prepared by TEMPO oxidation pretreatment and mechanical treatment, cellulose nano-crystals prepared by wood pulp fiber hydrolyzed by sulfuric acid and bacterial cellulose.

9. The method for preparing the lignin/PBAT composite material according to any one of claims 1 to 8, wherein PBAT, lignin or lignin/SiO₂Simultaneously adding the composite nano particles, the antioxidant, the metal coordinate bond auxiliary agent, the plasticizer and the micro or nano cellulose into a plastic stirrer, mixing at normal temperature, and discharging to obtain a premix; adding the premix into a double-screw extruder, blending, extruding and granulating to obtain the lignin/PBAT composite material;

the mixing time at the normal temperature is 5-20 min;

the processing temperature of the double-screw extruder is 120-190 ℃;

the speed of the double-screw extruder is 15-50 rpm.

10. Use of a lignin/PBAT composite according to any one of claims 1 to 8.

Background

Polybutylene adipate terephthalate (PBAT) is prepared by carrying out polycondensation reaction on terephthalic acid, adipic acid and 1, 4-butanediol. PBAT has higher elongation at break, good flexibility, mechanical property equivalent to that of PE, good biodegradability and wide prospect in the fields of food packaging, agriculture and biomedicine. However, despite the many potential applications, the disadvantages of high cost, poor radiation resistance leading to impaired mechanical properties, poor water resistance, poor gas barrier properties, etc., still limit their wide-range applications, particularly in the field of packaging and mulching.

Lignin is a natural organic polymer with an aromatic ring structure existing in higher plants, and has a large storage capacity and a rich source. Lignin contains a large number of functional groups such as benzene rings, phenolic hydroxyl groups, alcoholic hydroxyl groups, carboxyl groups and the like, and has excellent ultraviolet resistance and ageing resistance [ Green chem.,2015,17(1):320 ]. In recent years, in order to solve the serious environmental pollution caused by the traditional plastics, due to the worry about the gradual exhaustion of petrochemical resources and the importance on the utilization of biomass resources, the utilization of biomass modified degradable plastics becomes a research hotspot. Therefore, the lignin is used for modifying the PBAT, so that the PBAT is endowed with excellent ultraviolet resistance, the production cost of PBAT related products is reduced, high-value utilization of the lignin is realized, and the method has important significance for promoting effective utilization of biomass resources and greening development of high polymer materials.

The lignin molecules contain a large amount of polyphenol and quinoid structures, so that the lignin molecules are easy to agglomerate, have poor compatibility with a polymer matrix and are difficult to disperse, and the direct introduction of the lignin into the PBAT matrix can inevitably cause serious phase separation of the lignin and the PBAT matrix, thereby causing serious negative effects on the material performance. Although there are a lot of research reports on the preparation of composite materials by blending lignin and PBAT at home and abroad, two problems still exist at present: 1. the mechanical property of the prepared lignin modified PBAT composite material is seriously reduced; 2. the lignin modification process is complicated, and the cost cannot be effectively reduced. In the field of lignin modified PBAT, Qianqiu Xing et al ACS Sustainable chem.Eng.2017,5,10342-10351 blend PBAT and bio-based oleic acid or 10-undecylenic acid modified lignin, and the obtained composite material is processed into a film by compression molding, so that the ultraviolet resistance of the obtained composite material is improved, but the load capacity of the lignin is low, the cost cannot be effectively reduced, and the mechanical property is not improved. Tong-Qi Yuan et al ACS Sustainable chem. Eng.2020,8, 5338-containing 5346 improve the interfacial compatibility between PBAT and industrial lignin by adopting two strategies of blending methylated lignin and PBAT, adding maleic anhydride grafted PBAT as a compatilizer and the like, wherein the lignin content in the composite material prepared by the two methods reaches 40-60 percent, but the mechanical property is poor, and the practical application is difficult. Patent CN106832801B of Shikinan et al discloses [ a lignin-modified PBAT biodegradable plastic and a preparation method thereof ], the lignin, the PBAT and a processing aid are directly blended, the problem of poor interface compatibility of the lignin and the PBAT is not solved, and the obtained composite material has reduced elongation at break and deviation of toughness.

Therefore, in order to prepare a lignin/PBAT composite material with excellent mechanical properties, basic scientific problems such as poor dispersibility of lignin in a PBAT matrix and poor interface compatibility with the PBAT are urgently needed to be solved.

Disclosure of Invention

In order to solve the defects and shortcomings of the prior art, the invention mainly aims to provide a lignin/PBAT composite material.

The invention also aims to provide a preparation method of the lignin/PBAT composite material.

Still another object of the present invention is to provide the use of the above lignin/PBAT composite material.

The purpose of the invention is realized by the following technical scheme:

a lignin/PBAT composite material is prepared from the following components in percentage by mass:

preferably, the lignin/PBAT composite material is prepared from the following components in percentage by mass:

more preferably, the lignin/PBAT composite material is prepared from the following components in percentage by mass:

still further preferably, the lignin/PBAT composite material is prepared from the following components in percentage by mass:

or is prepared from the following components in percentage by mass:

the PBAT is polybutylene adipate terephthalate, well known in the art, as a terpolymer of adipic acid, terephthalic acid, and 1, 4-butanediol.

Preferably, the lignin can be one or more of alkali lignin obtained by alkali pulping in paper industry, enzymatic lignin extracted by ethanol produced by fermentation of lignocellulose, or organic solvent lignin extracted from lignocellulose by an organic solvent method.

Preferably, the lignin/SiO₂The preparation method of the composite nano-particles comprises the following steps: performing ultrasonic pre-dispersion on nano silicon dioxide in an ethanol/water mixed system, adding lignin under an alkaline condition, adding acid under a stirring condition to adjust the pH value to acidity, performing coprecipitation reaction, then aging, performing centrifugal filtration, washing precipitates, and then drying by adopting an infrared drying method, or drying a sample by adopting a spray drying method after aging, thereby finally preparing the composite nano particles.

Preferably, the lignin is mixed with SiO₂The mass ratio of (A) to (B) is 90: 10-70: 30.

More preferably, the pH is 2 to 7, and still more preferably 3 to 5.

More preferably, the aging time is 0.5-4 h, and further preferably 1-2 h.

More preferably, the aging temperature is 20-100 ℃, further preferably 30-80 ℃, and further preferably 40-70 ℃.

More preferably, the mass ratio of ethanol to water in the ethanol/water mixed system is 1: 1-3: 2.

preferably, the antioxidant is at least one of butylated hydroxyanisole, dibutyl hydroxy toluene, pentaerythrityl tetrakis [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ], tert-butyl-p-diphenol, diisodecyl benzene phosphite, pentaerythritol diphosphite and methyl 3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate.

Preferably, the metal coordination bond auxiliary agent is at least one of zinc oxalate, zinc acetate, zinc methacrylate, zinc acetylacetonate, iron oxalate, iron acetate and calcium acetate.

More preferably, the metal coordination bond auxiliary is at least one of iron oxalate, zinc acetylacetonate, zinc methacrylate, zinc acetate and iron acetylacetonate.

Preferably, the plasticizer is at least one of triacetin, epoxidized soybean oil, acetyl tri-n-butyl citrate, triethyl citrate, and tributyl citrate.

Preferably, the micron cellulose is micron cellulose obtained by alkaline pulping; the nano-cellulose is at least one of cellulose nano-fibrils (CNF) prepared by TEMPO oxidation pretreatment and mechanical treatment, cellulose nano-crystals (CNC) prepared by wood pulp fiber hydrolyzed by sulfuric acid and bacterial cellulose.

The preparation method of the lignin/PBAT composite material comprises the following steps:

mixing PBAT, lignin or lignin/SiO₂Simultaneously adding the composite nano particles, the antioxidant, the metal coordinate bond auxiliary agent, the plasticizer and the micro or nano cellulose into a plastic stirrer, mixing at normal temperature, and discharging to obtain a premix; and adding the premix into a double-screw extruder, blending, extruding and granulating to obtain the lignin/PBAT composite material.

Preferably, the mixing time at normal temperature is 5-20 min.

Preferably, the processing temperature of the double-screw extruder is 120-190 ℃, more preferably 130-180 ℃, and even more preferably 140-160 ℃.

Preferably, the speed of the twin-screw extruder is 15 to 50rpm, and more preferably 20 to 40 rpm.

The application of the lignin/PBAT composite material in the fields of mulching films and plastic bags is provided.

According to the invention, lignin and an additive are added into the PBAT, and a metal coordination bond in a non-covalent bond connection is constructed between the phase interfaces of the lignin and the PBAT, so that the metal coordination bond can promote lignin particles to be dispersed in the PBAT matrix more uniformly, can improve the interface compatibility between the lignin and the PBAT, and can enhance the interface bonding force between the lignin and the PBAT. The introduction of the micro or nano cellulose can further enhance the hydrogen bond bridging effect between the lignin and the PBAT, and further improve the interface bonding force. The interface bonding force of the lignin and the PBAT is improved, and meanwhile, the lignin and hydrophilic polar functional groups such as hydroxyl, carboxyl and the like on a PBAT molecular chain are subjected to partial esterification reaction, so that the hydrophilicity of the composite material is weakened, the composite material is enhanced and toughened, the hydrophobicity is improved, and the problems of poor mechanical property and poor PBAT water vapor barrier property caused by poor compatibility between the lignin and the PBAT are solved.

The method can obtain the composite material with different mechanical properties and hydrophobicity by adjusting the dosage of lignin, an antioxidant, a metal coordination bond auxiliary agent, a plasticizer and micron or nano cellulose in the composite material, and the composite material has the tensile strength of 9-40 MPa, the elongation at break of 135-700% and the water static contact angle of 80-110 degrees.

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

1. the method utilizes lignin byproducts as raw materials, prepares lignin nano-particles with controllable hydrophilic and hydrophobic polarities by regulating and controlling the aggregation microstructure of lignin, and constructs a nano-microphase separation structure in a composite material matrix; meanwhile, a large number of oxygen-containing polar functional groups such as carboxyl and the like of the lignin are utilized, and dynamic bonds such as hydrogen bonds, coordination bonds and the like are constructed between the phase interfaces of the lignin and the PBAT under the action of the micro or nano cellulose and the metal coordination bond auxiliary agent, so that the interface acting force is improved, the dispersion and stress transfer of the lignin in a polymer are promoted, the composite material is simultaneously enhanced and toughened, and the problems of poor compatibility and difficult dispersion of the lignin and the polymer are solved.

2. The invention utilizes the amphiphilic structure characteristic of lignin to prepare the lignin nano-particles with controllable hydrophilic and hydrophobic polarities, and regulates and controls the water resistance and the water vapor barrier property of the PBAT composite material.

3. According to the invention, a stronger interface dynamic bond function is constructed on the phase interface of the lignin and the PBAT, and the ultraviolet shielding and anti-aging functions of the lignin are utilized to regulate and control the degradation performance, improve the weather resistance of the PBAT composite material in outdoor use and delay the degradation speed.

Detailed Description

The present invention will be described in further detail with reference to examples, but the embodiments of the present invention are not limited thereto.

Those who do not specify specific conditions in the examples of the present invention follow conventional conditions or conditions recommended by the manufacturer. The raw materials, reagents and the like which are not indicated for manufacturers are all conventional products which can be obtained by commercial purchase.

Example 1

Quantitatively adding 95 parts of dry PBAT, 5 parts of dry alkali lignin powder, 5 parts of nanocellulose, 0.3 part of ferric oxalate, 0.2 part of pentaerythrityl tetrakis [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ] and 0.3 part of epoxidized soybean oil into a plastic stirrer in sequence at 25 ℃, and stirring at high speed for 10min at normal temperature to obtain a lignin/PBAT premix; then extruding and granulating the lignin/PBAT premix by a double-screw extruder, controlling the extrusion temperature to be 120-140 ℃ and the rotating speed of the double screws to be 25rpm, and thus obtaining lignin/PBAT composite plastic particles; drying the plastic particles in a vacuum oven at 50 ℃ for 12 hours under vacuum condition; and finally, putting the dried lignin/PBAT composite plastic particles into a plate vulcanizing machine, and vulcanizing for 30min at the temperature of 150 ℃ and under the pressure of 15MPa to obtain the lignin/PBAT composite plastic sheet.

Example 2

Quantitatively adding 95 parts of dry PBAT, 5 parts of dry alkali lignin powder, 2 parts of nanocellulose, 0.2 part of tetra [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid ] pentaerythritol ester, 0.5 part of zinc oxalate and 0.3 part of epoxidized soybean oil into a plastic stirrer in sequence at 25 ℃, and stirring at normal temperature and high speed for 10min to obtain a lignin/PBAT premix; then extruding and granulating the lignin/PBAT premix by a double-screw extruder, controlling the extrusion temperature to be 120-140 ℃ and the rotating speed of the double screws to be 25rpm, and thus obtaining lignin/PBAT composite plastic particles; drying the plastic particles in a vacuum oven at 50 ℃ for 12 hours under vacuum condition; and finally, putting the dried lignin/PBAT composite plastic particles into a plate vulcanizing machine, and vulcanizing for 30min at the temperature of 150 ℃ and under the pressure of 15MPa to obtain the lignin/PBAT composite plastic sheet.

Example 3

Quantitatively adding 95 parts of dry PBAT, 5 parts of dry enzymatic hydrolysis lignin powder, 5 parts of nanocellulose, 0.2 part of tetra [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid ] pentaerythritol ester, 0.5 part of zinc acetylacetonate and 0.3 part of epoxidized soybean oil into a plastic stirring machine in sequence at 25 ℃, and stirring at high speed for 10min at normal temperature to obtain a lignin/PBAT premix; then extruding and granulating the lignin/PBAT premix by a double-screw extruder, controlling the extrusion temperature to be 120-140 ℃ and the rotating speed of the double screws to be 25rpm, and thus obtaining lignin/PBAT composite plastic particles; drying the plastic particles in a vacuum oven at 50 ℃ for 12 hours under vacuum condition; and finally, putting the dried lignin/PBAT composite plastic particles into a plate vulcanizing machine, and vulcanizing for 30min at the temperature of 150 ℃ and under the pressure of 15MPa to obtain the lignin/PBAT composite plastic sheet.

Example 4

Quantitatively adding 90 parts of dry PBAT, 10 parts of dry enzymatic hydrolysis lignin powder, 8 parts of micron cellulose, 0.5 part of zinc methacrylate, 0.2 part of tetra [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid ] pentaerythritol ester and 0.3 part of epoxidized soybean oil into a plastic stirring machine in sequence at 25 ℃, and stirring at high speed for 10min at normal temperature to obtain lignin/PBAT premix; then extruding and granulating the lignin/PBAT premix by a double-screw extruder, controlling the extrusion temperature to be 120-140 ℃ and the rotating speed of the double screws to be 25rpm, and thus obtaining lignin/PBAT composite plastic particles; drying the plastic particles in a vacuum oven at 50 ℃ for 12 hours under vacuum condition; and finally, putting the dried lignin/PBAT composite plastic particles into a plate vulcanizing machine, and vulcanizing for 30min at the temperature of 150 ℃ and under the pressure of 15MPa to obtain the lignin/PBAT composite plastic sheet.

Example 5

Quantitatively adding 90 parts of dry PBAT, 10 parts of dry alkali lignin powder, 5 parts of micron cellulose, 0.2 part of tetra [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid ] pentaerythritol ester, 0.5 part of zinc acetate and 0.3 part of tributyl citrate into a plastic stirring machine in sequence at the temperature of 25 ℃, and stirring at high speed for 10min at normal temperature to obtain lignin/PBAT premix; then extruding and granulating the lignin/PBAT premix by a double-screw extruder, controlling the extrusion temperature to be 120-140 ℃ and the rotating speed of the double screws to be 25rpm, and thus obtaining lignin/PBAT composite plastic particles; drying the plastic particles in a vacuum oven at 50 ℃ for 12 hours under vacuum condition; and finally, putting the dried lignin/PBAT composite plastic particles into a plate vulcanizing machine, and vulcanizing for 30min at the temperature of 150 ℃ and under the pressure of 15MPa to obtain the lignin/PBAT composite plastic sheet.

Example 6

Quantitatively adding 90 parts of dry PBAT, 10 parts of lignin powder obtained by a dry organic solvent method, 8 parts of nano-cellulose, 0.2 part of tert-butyl-p-diphenol, 0.5 part of zinc acetate and 0.3 part of tributyl citrate into a plastic stirring machine at 25 ℃, and stirring at a high speed for 10min at normal temperature to obtain lignin/PBAT premix; then extruding and granulating the lignin/PBAT premix by a double-screw extruder, controlling the extrusion temperature to be 120-140 ℃ and the rotating speed of the double screws to be 50rpm, and thus obtaining lignin/PBAT composite plastic particles; drying the plastic particles in a vacuum oven at 50 ℃ for 12 hours under vacuum condition; and finally, putting the dried lignin/PBAT composite plastic particles into a plate vulcanizing machine, and vulcanizing for 30min at the temperature of 150 ℃ and under the pressure of 15MPa to obtain the lignin/PBAT composite plastic sheet.

Example 7

Quantitatively adding 80 parts of dry PBAT, 20 parts of dry alkali lignin powder, 15 parts of micron cellulose, 0.3 part of zinc oxalate, 0.2 part of tert-butyl-p-diphenol and 0.3 part of epoxy soybean oil into a plastic stirrer in sequence at 25 ℃, and stirring at normal temperature and high speed for 10min to obtain lignin/PBAT premix; then extruding and granulating the lignin/PBAT premix by a double-screw extruder, controlling the extrusion temperature to be 120-140 ℃ and the rotating speed of the double screws to be 25rpm, and thus obtaining lignin/PBAT composite plastic particles; drying the plastic particles in a vacuum oven at 50 ℃ for 12 hours under vacuum condition; and finally, putting the dried lignin/PBAT composite plastic particles into a plate vulcanizing machine, and vulcanizing for 30min at the temperature of 150 ℃ and under the pressure of 15MPa to obtain the lignin/PBAT composite plastic sheet.

Example 8

Quantitatively adding 80 parts of dried PBAT, 20 parts of dried enzymatic hydrolysis lignin powder, 8 parts of micron cellulose, 0.2 part of tert-butyl-p-diphenol, 0.6 part of zinc acetate and 0.3 part of epoxidized soybean oil into a plastic stirrer in sequence at 25 ℃, and stirring at high speed for 10min at normal temperature to obtain lignin/PBAT premix; then extruding and granulating the lignin/PBAT premix by a double-screw extruder, controlling the extrusion temperature to be 120-140 ℃ and the rotating speed of the double screws to be 25rpm, and thus obtaining lignin/PBAT composite plastic particles; drying the plastic particles in a vacuum oven at 50 ℃ for 12 hours under vacuum condition; and finally, putting the dried lignin/PBAT composite plastic particles into a plate vulcanizing machine, and vulcanizing for 30min at the temperature of 150 ℃ and under the pressure of 15MPa to obtain the lignin/PBAT composite plastic sheet.

Example 9

Quantitatively adding 80 parts of dried PBAT, 20 parts of dried enzymatic hydrolysis lignin powder, 10 parts of nano-cellulose, 0.2 part of tert-butyl-p-diphenol, 0.6 part of iron acetylacetonate and 0.3 part of epoxidized soybean oil into a plastic stirring machine in sequence at 25 ℃, and stirring at high speed for 10min at normal temperature to obtain lignin/PBAT premix; then extruding and granulating the lignin/PBAT premix by a double-screw extruder, controlling the extrusion temperature to be 120-140 ℃ and the rotating speed of the double screws to be 25rpm, and thus obtaining lignin/PBAT composite plastic particles; drying the plastic particles in a vacuum oven at 50 ℃ for 12 hours under vacuum condition; and finally, putting the dried lignin/PBAT composite plastic particles into a plate vulcanizing machine, and vulcanizing for 30min at the temperature of 150 ℃ and under the pressure of 15MPa to obtain the lignin/PBAT composite plastic sheet.

Example 10

Quantitatively adding 70 parts of dry PBAT, 30 parts of dry enzymatic hydrolysis lignin powder, 15 parts of nanocellulose, 0.6 part of zinc acetylacetonate, 0.2 part of pentaerythrityl tetrakis [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ] and 0.3 part of epoxidized soybean oil into a plastic stirring machine in sequence at the temperature of 25 ℃, and stirring at high speed for 10min at normal temperature to obtain lignin/PBAT premix; then extruding and granulating the lignin/PBAT premix by a double-screw extruder, controlling the extrusion temperature to be 120-140 ℃ and the rotating speed of the double screws to be 25rpm, and thus obtaining lignin/PBAT composite plastic particles; drying the plastic particles in a vacuum oven at 50 ℃ for 12 hours under vacuum condition; and finally, putting the dried lignin/PBAT composite plastic particles into a plate vulcanizing machine, and vulcanizing for 30min at the temperature of 150 ℃ and under the pressure of 15MPa to obtain the lignin/PBAT composite plastic sheet.

Example 11

Quantitatively adding 70 parts of dry PBAT, 30 parts of dry alkali lignin powder, 10 parts of nanocellulose, 0.2 part of tetra [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid ] pentaerythritol ester, 1.5 parts of zinc acetate and 0.3 part of epoxidized soybean oil into a plastic stirrer in sequence at 25 ℃, and stirring at normal temperature and high speed for 10min to obtain a lignin/PBAT premix; then extruding and granulating the lignin/PBAT premix by a double-screw extruder, controlling the extrusion temperature to be 120-140 ℃ and the rotating speed of the double screws to be 25rpm, and thus obtaining lignin/PBAT composite plastic particles; drying the plastic particles in a vacuum oven at 50 ℃ for 12 hours under vacuum condition; and finally, putting the dried lignin/PBAT composite plastic particles into a plate vulcanizing machine, and vulcanizing for 30min at the temperature of 150 ℃ and under the pressure of 15MPa to obtain the lignin/PBAT composite plastic sheet.

Example 12

Quantitatively adding 70 parts of dry PBAT, 30 parts of lignin powder obtained by a dry organic solvent method, 15 parts of micron cellulose, 0.2 part of tetra [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid ] pentaerythritol ester, 1.5 parts of zinc acetate and 0.3 part of epoxidized soybean oil into a plastic stirrer in sequence at the temperature of 25 ℃, and stirring at a high speed for 10min at normal temperature to obtain a lignin/PBAT premix; then extruding and granulating the lignin/PBAT premix by a double-screw extruder, controlling the extrusion temperature to be 120-140 ℃ and the rotating speed of the double screws to be 25rpm, and thus obtaining lignin/PBAT composite plastic particles; drying the plastic particles in a vacuum oven at 50 ℃ for 12 hours under vacuum condition; and finally, putting the dried lignin/PBAT composite plastic particles into a plate vulcanizing machine, and vulcanizing for 30min at the temperature of 150 ℃ and under the pressure of 15MPa to obtain the lignin/PBAT composite plastic sheet.

Example 13

Step 1: nano silicon dioxide is added into the mixture of 1: 1, ultrasonic pre-dispersing in an ethanol/water mixed system, adding alkali lignin under an alkaline condition, wherein the nano-dioxygenThe mass ratio of the silicon oxide to the alkali lignin is 20: 80, adding acid to adjust the pH value to 2 under the stirring condition, aging for 1h at 20 ℃ after coprecipitation reaction, centrifugally filtering and washing precipitates, and then drying by adopting an infrared drying method or drying a sample by adopting a spray drying method after aging to finally prepare the lignin/SiO₂Composite nanoparticles.

Step 2: in terms of parts by mass, 95 parts of dry PBAT and 5 parts of dry lignin/SiO are quantitatively added into a plastic stirrer in sequence at 25 DEG C₂Composite nano-particles, 5 parts of micron cellulose, 0.5 part of zinc methacrylate and 0.2 part of tetra [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid]Pentaerythritol ester and 0.3 part of epoxidized soybean oil are stirred at normal temperature and high speed for 10min to obtain lignin/PBAT premix; then extruding and granulating the lignin/PBAT premix by a double-screw extruder, controlling the extrusion temperature to be 120-140 ℃ and the rotating speed of the double screws to be 15rpm, and thus obtaining lignin/PBAT composite plastic particles; drying the plastic particles in a vacuum oven at 50 ℃ for 12 hours under vacuum condition; and finally, putting the dried lignin/PBAT composite plastic particles into a plate vulcanizing machine, and vulcanizing for 30min at the temperature of 150 ℃ and under the pressure of 15MPa to obtain the lignin/PBAT composite plastic sheet.

Example 14

Step 1 is the same as in example 13.

Step 2: in terms of parts by mass, 95 parts of dry PBAT and 5 parts of dry lignin/SiO are quantitatively added into a plastic stirrer in sequence at 25 DEG C₂Composite nano-particles, 10 parts of nano-cellulose and 0.2 part of tetra [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid]Pentaerythritol ester, 0.8 part of zinc acetylacetonate and 0.3 part of epoxidized soybean oil are stirred at high speed for 10min at normal temperature to obtain lignin/PBAT premix; then extruding and granulating the lignin/PBAT premix by a double-screw extruder, controlling the extrusion temperature to be 120-140 ℃ and the rotating speed of the double screws to be 15rpm, and thus obtaining lignin/PBAT composite plastic particles; drying the plastic particles in a vacuum oven at 50 ℃ for 12 hours under vacuum condition; and finally, putting the dried lignin/PBAT composite plastic particles into a plate vulcanizing machine, and vulcanizing for 30min at the temperature of 150 ℃ and under the pressure of 15MPa to obtain the lignin/PBAT composite plastic sheet.

Example 15

Step 1 is the same as in example 13.

Step 2: in terms of parts by mass, 95 parts of dry PBAT and 5 parts of dry lignin/SiO are quantitatively added into a plastic stirrer in sequence at 25 DEG C₂Composite nano-particles, 5 parts of nano-cellulose and 0.2 part of tetra [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid]Pentaerythritol ester, 0.8 part of zinc acetylacetonate and 0.3 part of epoxidized soybean oil are stirred at high speed for 10min at normal temperature to obtain lignin/PBAT premix; then extruding and granulating the lignin/PBAT premix by a double-screw extruder, controlling the extrusion temperature to be 120-140 ℃ and the rotating speed of the double screws to be 15rpm, and thus obtaining lignin/PBAT composite plastic particles; drying the plastic particles in a vacuum oven at 50 ℃ for 12 hours under vacuum condition; and finally, putting the dried lignin/PBAT composite plastic particles into a plate vulcanizing machine, and vulcanizing for 30min at the temperature of 150 ℃ and under the pressure of 15MPa to obtain the lignin/PBAT composite plastic sheet.

Example 16

Step 1: nano silicon dioxide is added into the mixture according to the mass ratio of 2: 3, performing ultrasonic pre-dispersion in an ethanol/water mixed system, and adding alkali lignin under an alkaline condition, wherein the mass ratio of the nano silicon dioxide to the alkali lignin is 20: 80, adding acid to adjust the pH value to 7 under the stirring condition, aging for 4h at 100 ℃ after coprecipitation reaction, centrifugally filtering and washing precipitates, and then drying by adopting an infrared drying method or drying a sample by adopting a spray drying method after aging to finally prepare the lignin/SiO₂Composite nanoparticles.

Step 2: in terms of parts by mass, 90 parts of dry PBAT and 10 parts of dry lignin/SiO are quantitatively added into a plastic stirrer in sequence at 25 DEG C₂Stirring the composite nano particles, 20 parts of nano cellulose, 0.6 part of zinc acetate, 0.2 part of dibutyl hydroxy toluene and 0.3 part of triethyl citrate at a high speed for 10min at normal temperature to obtain a lignin/PBAT premix; then extruding and granulating the lignin/PBAT premix by a double-screw extruder, controlling the extrusion temperature to be 120-140 ℃ and the rotating speed of the double screws to be 35rpm, and obtaining lignin/PBAT composite plastic particles; placing the plastic particles in a vacuum oven at 50 ℃ under vacuumDrying for 12 h; and finally, putting the dried lignin/PBAT composite plastic particles into a plate vulcanizing machine, and vulcanizing for 30min at the temperature of 150 ℃ and under the pressure of 15MPa to obtain the lignin/PBAT composite plastic sheet.

Example 17

Step 1 is the same as in example 16.

Step 2: in terms of parts by mass, 90 parts of dry PBAT and 10 parts of dry lignin/SiO are quantitatively added into a plastic stirrer in sequence at 25 DEG C₂Mixing composite nano particles, 8 parts of nano cellulose, 0.1 part of tert-butyl-p-diphenol, 0.2 part of ferric acetylacetonate and 0.1 part of glycerol triacetate at a high speed for 10min at normal temperature to obtain a lignin/PBAT premix; then extruding and granulating the lignin/PBAT premix by a double-screw extruder, controlling the extrusion temperature to be 120-140 ℃ and the rotating speed of the double screws to be 25rpm, and thus obtaining lignin/PBAT composite plastic particles; drying the plastic particles in a vacuum oven at 50 ℃ for 12 hours under vacuum condition; and finally, putting the dried lignin/PBAT composite plastic particles into a plate vulcanizing machine, and vulcanizing for 30min at the temperature of 150 ℃ and under the pressure of 15MPa to obtain the lignin/PBAT composite plastic sheet.

Example 18

Step 1 is the same as in example 16.

Step 2: in terms of parts by mass, 90 parts of dry PBAT and 10 parts of dry lignin/SiO are quantitatively added into a plastic stirrer in sequence at 25 DEG C₂Mixing composite nano particles, 15 parts of nano cellulose, 0.1 part of tert-butyl-p-diphenol, 0.6 part of zinc acetate and 0.1 part of glycerol triacetate at a high speed for 10min at normal temperature to obtain a lignin/PBAT premix; then extruding and granulating the lignin/PBAT premix by a double-screw extruder, controlling the extrusion temperature to be 120-140 ℃ and the rotating speed of the double screws to be 25rpm, and thus obtaining lignin/PBAT composite plastic particles; drying the plastic particles in a vacuum oven at 50 ℃ for 12 hours under vacuum condition; and finally, putting the dried lignin/PBAT composite plastic particles into a plate vulcanizing machine, and vulcanizing for 30min at the temperature of 150 ℃ and under the pressure of 15MPa to obtain the lignin/PBAT composite plastic sheet.

Example 19

Step 1 is the same as in example 16.

Step 2: quantitatively adding 70 parts of dry PBAT and 30 parts of dry lignin/SiO into a plastic stirrer at 25 DEG C₂Mixing composite nano particles, 15 parts of nano cellulose, 0.8 part of ferric acetylacetonate, 0.8 part of tert-butyl p-diphenol and 0.6 part of glycerol triacetate at a high speed for 10min at normal temperature to obtain a lignin/PBAT premix; then extruding and granulating the lignin/PBAT premix by a double-screw extruder, controlling the extrusion temperature to be 120-140 ℃ and the rotating speed of the double screws to be 25rpm, and thus obtaining lignin/PBAT composite plastic particles; drying the plastic particles in a vacuum oven at 50 ℃ for 12 hours under vacuum condition; and finally, putting the dried lignin/PBAT composite plastic particles into a plate vulcanizing machine, and vulcanizing for 30min at the temperature of 150 ℃ and under the pressure of 15MPa to obtain the lignin/PBAT composite plastic sheet.

Example 20

Step 1 is the same as in example 16.

Step 2: quantitatively adding 70 parts of dry PBAT and 30 parts of dry lignin/SiO into a plastic stirrer at 25 DEG C₂Mixing composite nano particles, 5 parts of micron cellulose, 0.8 part of tert-butyl-p-diphenol, 1 part of zinc oxalate and 0.6 part of glycerol triacetate at a high speed for 10min at normal temperature to obtain a lignin/PBAT premix; then extruding and granulating the lignin/PBAT premix by a double-screw extruder, controlling the extrusion temperature to be 120-140 ℃ and the rotating speed of the double screws to be 25rpm, and thus obtaining lignin/PBAT composite plastic particles; drying the plastic particles in a vacuum oven at 50 ℃ for 12 hours under vacuum condition; and finally, putting the dried lignin/PBAT composite plastic particles into a plate vulcanizing machine, and vulcanizing for 30min at the temperature of 150 ℃ and under the pressure of 15MPa to obtain the lignin/PBAT composite plastic sheet.

Example 21

Step 1 is the same as in example 16.

Step 2: quantitatively adding 70 parts of dry PBAT and 30 parts of dry lignin/SiO into a plastic stirrer at 25 DEG C₂Composite nano-particles, 15 parts of nano-cellulose, 0.6 part of tert-butyl-p-diphenol, 1 part of zinc methacrylate, 0.6 part of glycerol triacetate, and the components are mixed at normal temperature and high temperatureStirring rapidly for 10min to obtain lignin/PBAT premix; then extruding and granulating the lignin/PBAT premix by a double-screw extruder, controlling the extrusion temperature to be 120-140 ℃ and the rotating speed of the double screws to be 25rpm, and thus obtaining lignin/PBAT composite plastic particles; drying the plastic particles in a vacuum oven at 50 ℃ for 12 hours under vacuum condition; and finally, putting the dried lignin/PBAT composite plastic particles into a plate vulcanizing machine, and vulcanizing for 30min at the temperature of 150 ℃ and under the pressure of 15MPa to obtain the lignin/PBAT composite plastic sheet.

Example 22

Step 1 is the same as in example 16.

Step 2: based on the mass parts, 55 parts of dry PBAT and 45 parts of dry lignin/SiO are quantitatively added into a plastic stirrer in sequence at the temperature of 25 DEG C₂Stirring composite nano particles, 15 parts of micron cellulose, 0.6 part of dibutyl hydroxy toluene, 1.5 parts of zinc oxalate and 0.6 part of tributyl citrate at high speed for 10min at normal temperature to obtain a lignin/PBAT premix; then extruding and granulating the lignin/PBAT premix by a double-screw extruder, controlling the extrusion temperature to be 120-160 ℃ and the rotating speed of the double screws to be 50rpm, and thus obtaining lignin/PBAT composite plastic particles; drying the plastic particles in a vacuum oven at 50 ℃ for 12 hours under vacuum condition; and finally, putting the dried lignin/PBAT composite plastic particles into a plate vulcanizing machine, and vulcanizing for 30min at the temperature of 150 ℃ and under the pressure of 15MPa to obtain the lignin/PBAT composite plastic sheet.

Control sample

100 parts of dry PBAT plastic particles are put into a plate vulcanizing machine by mass, and the pure PBAT plastic sheet can be obtained after 30min of vulcanization under the conditions of 150 ℃ and 15 MPa.

Comparative example 1

Quantitatively adding 95 parts of dry PBAT and 5 parts of dry alkali lignin powder into a plastic stirrer in sequence at 25 ℃, and stirring at a high speed for 10min at normal temperature to obtain lignin/PBAT premix; then extruding and granulating the lignin/PBAT premix by a double-screw extruder, controlling the extrusion temperature to be 120-140 ℃ and the rotating speed of the double screws to be 25rpm, and thus obtaining lignin/PBAT composite plastic particles; drying the plastic particles in a vacuum oven at 50 ℃ for 12 hours under vacuum condition; and finally, putting the dried lignin/PBAT composite plastic particles into a plate vulcanizing machine, and vulcanizing for 30min at the temperature of 150 ℃ and under the pressure of 15MPa to obtain the lignin/PBAT composite plastic sheet.

The comparative example was 5 parts lignin loading with no cellulose added and no additives added.

Comparative example 2

Quantitatively adding 95 parts of dry PBAT, 5 parts of dry lignin powder, 0.3 part of tert-butyl-p-diphenol and 0.5 part of triethyl citrate into a plastic stirrer in sequence at 25 ℃, and stirring at a high speed for 10min at normal temperature to obtain lignin/PBAT premix; then extruding and granulating the lignin/PBAT premix by a double-screw extruder, controlling the extrusion temperature to be 120-140 ℃ and the rotating speed of the double screws to be 25rpm, and thus obtaining lignin/PBAT composite plastic particles; drying the plastic particles in a vacuum oven at 50 ℃ for 12 hours under vacuum condition; and finally, putting the dried lignin/PBAT composite plastic particles into a plate vulcanizing machine, and vulcanizing for 30min at the temperature of 150 ℃ and under the pressure of 15MPa to obtain the lignin/PBAT composite plastic sheet.

The comparative example is 5 parts lignin loading, no cellulose, no metal coordination bond promoter.

Comparative example 3

Quantitatively adding 90 parts of dried PBAT and 10 parts of dried lignin powder into a plastic stirring machine in sequence at 25 ℃, and stirring at a high speed for 10min at normal temperature to obtain lignin/PBAT premix; then extruding and granulating the lignin/PBAT premix by a double-screw extruder, controlling the extrusion temperature to be 120-140 ℃ and the rotating speed of the double screws to be 25rpm, and thus obtaining lignin/PBAT composite plastic particles; drying the plastic particles in a vacuum oven at 50 ℃ for 12 hours under vacuum condition; and finally, putting the dried lignin/PBAT composite plastic particles into a plate vulcanizing machine, and vulcanizing for 30min at the temperature of 150 ℃ and under the pressure of 15MPa to obtain the lignin/PBAT composite plastic sheet.

The comparative example was 10 parts lignin loading with no cellulose added and no additives added.

Comparative example 4

Quantitatively adding 90 parts of dry PBAT, 10 parts of dry lignin powder, 0.2 part of tetra [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid ] pentaerythritol ester and 0.3 part of tributyl citrate into a plastic stirrer in sequence at 25 ℃, and stirring at high speed for 10min at normal temperature to obtain lignin/PBAT premix; then extruding and granulating the lignin/PBAT premix by a double-screw extruder, controlling the extrusion temperature to be 120-140 ℃ and the rotating speed of the double screws to be 25rpm, and thus obtaining lignin/PBAT composite plastic particles; drying the plastic particles in a vacuum oven at 50 ℃ for 12 hours under vacuum condition; and finally, putting the dried lignin/PBAT composite plastic particles into a plate vulcanizing machine, and vulcanizing for 30min at the temperature of 150 ℃ and under the pressure of 15MPa to obtain the lignin/PBAT composite plastic sheet.

The comparative example is 10 parts lignin loading, no cellulose, no metal coordination bond promoter.

Comparative example 5

Quantitatively adding 80 parts of dry PBAT and 20 parts of dry lignin powder into a plastic stirrer in sequence at 25 ℃, and stirring at a high speed for 10min at normal temperature to obtain lignin/PBAT premix; then extruding and granulating the lignin/PBAT premix by a double-screw extruder, controlling the extrusion temperature to be 120-140 ℃ and the rotating speed of the double screws to be 25rpm, and thus obtaining lignin/PBAT composite plastic particles; drying the plastic particles in a vacuum oven at 50 ℃ for 12 hours under vacuum condition; and finally, putting the dried lignin/PBAT composite plastic particles into a plate vulcanizing machine, and vulcanizing for 30min at the temperature of 150 ℃ and under the pressure of 15MPa to obtain the lignin/PBAT composite plastic sheet.

The comparative example was 20 parts lignin loading with no cellulose added and no additives added.

Comparative example 6

Quantitatively adding 80 parts of dry PBAT, 20 parts of dry lignin powder, 15 parts of micron cellulose, 0.2 part of tetra [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid ] pentaerythritol ester and 0.3 part of epoxidized soybean oil into a plastic stirrer in sequence at the temperature of 25 ℃, and stirring at high speed for 10min at normal temperature to obtain a lignin/PBAT premix; then extruding and granulating the lignin/PBAT premix by a double-screw extruder, controlling the extrusion temperature to be 120-140 ℃ and the rotating speed of the double screws to be 25rpm, and thus obtaining lignin/PBAT composite plastic particles; drying the plastic particles in a vacuum oven at 50 ℃ for 12 hours under vacuum condition; and finally, putting the dried lignin/PBAT composite plastic particles into a plate vulcanizing machine, and vulcanizing for 30min at the temperature of 150 ℃ and under the pressure of 15MPa to obtain the lignin/PBAT composite plastic sheet.

In this comparative example, no cellulose and no metal coordination bond promoter were added at 20 parts lignin loading.

Comparative example 7

Quantitatively adding 70 parts of dry PBAT and 30 parts of dry lignin powder into a plastic stirrer in sequence at 25 ℃, and stirring at a high speed for 10min at normal temperature to obtain lignin/PBAT premix; then extruding and granulating the lignin/PBAT premix by a double-screw extruder, controlling the extrusion temperature to be 120-140 ℃ and the rotating speed of the double screws to be 25rpm, and thus obtaining lignin/PBAT composite plastic particles; drying the plastic particles in a vacuum oven at 50 ℃ for 12 hours under vacuum condition; and finally, putting the dried lignin/PBAT composite plastic particles into a plate vulcanizing machine, and vulcanizing for 30min at the temperature of 150 ℃ and under the pressure of 15MPa to obtain the lignin/PBAT composite plastic sheet.

The comparative example was 30 parts lignin loading with no cellulose added and no additives added.

Comparative example 8

Step 1 is the same as in example 13.

Step 2: quantitatively adding 70 parts of dry PBAT and 30 parts of dry lignin/SiO into a plastic stirrer at 25 DEG C₂Mixing the composite nano particles, 0.6 part of tert-butyl-p-diphenol and 0.6 part of glycerol triacetate at a high speed for 10min at normal temperature to obtain a lignin/PBAT premix; then extruding and granulating the lignin/PBAT premix by a double-screw extruder, controlling the extrusion temperature to be 120-140 ℃ and the rotating speed of the double screws to be 25rpm, and thus obtaining lignin/PBAT composite plastic particles; drying the plastic particles in a vacuum oven at 50 ℃ for 12 hours under vacuum condition; finally, putting the dried lignin/PBAT composite plastic particles into a flat plateAnd vulcanizing for 30min at 150 ℃ and 15MPa by using a vulcanizing machine to obtain the lignin/PBAT composite plastic sheet.

In the comparative example, no cellulose and no metal coordination bond assistant were added at a lignin loading of 30 parts.

Comparative example 9

Quantitatively adding 55 parts of dried PBAT and 45 parts of dried lignin powder into a plastic stirring machine in sequence at 25 ℃, and stirring at a high speed for 10min at normal temperature to obtain lignin/cellulose/PBAT premix; then extruding and granulating the lignin/cellulose/PBAT premix by a double-screw extruder, controlling the extrusion temperature to be 120-140 ℃ and the rotating speed of the double screws to be 25rpm, and thus obtaining lignin/cellulose/PBAT composite plastic particles; drying the plastic particles in a vacuum oven at 50 ℃ for 12 hours under vacuum condition; and finally, putting the dried lignin/PBAT composite plastic particles into a plate vulcanizing machine, and vulcanizing for 30min at the temperature of 150 ℃ and under the pressure of 15MPa to obtain the lignin/cellulose/PBAT composite plastic sheet.

The comparative example was 45 parts lignin loading with no cellulose added and no additives added.

Comparative example 10

Quantitatively adding 55 parts of dried PBAT, 45 parts of dried lignin powder, 0.3 part of tetra [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid ] pentaerythritol ester and 0.3 part of epoxidized soybean oil into a plastic stirrer in sequence at 25 ℃, and stirring at high speed for 10min at normal temperature to obtain lignin/cellulose/PBAT premix; then extruding and granulating the lignin/cellulose/PBAT premix by a double-screw extruder, controlling the extrusion temperature to be 120-140 ℃ and the rotating speed of the double screws to be 25rpm, and thus obtaining lignin/cellulose/PBAT composite plastic particles; drying the plastic particles in a vacuum oven at 50 ℃ for 12 hours under vacuum condition; and finally, putting the dried lignin/PBAT composite plastic particles into a plate vulcanizing machine, and vulcanizing for 30min at the temperature of 150 ℃ and under the pressure of 15MPa to obtain the lignin/cellulose/PBAT composite plastic sheet.

This comparative example is 45 parts lignin loading with no cellulose added and no metal coordination bond promoter added.

The lignin/PBAT composite plastic sheets of the examples and the comparative examples are prepared into sample bars meeting GBT 1040-2006 standards, and an MTS universal tester is adopted to test mechanical property data such as tensile strength, elongation at break and the like, and the results are shown in Table 1.

Table 1 results of tensile testing of some samples

Sample (I)	Elongation at break/%	Tensile strength/MPa	Modulus of elasticity/MPa at 5% strain
				Example 2	694±20	35.5±2	86.4
Example 3	672±30	31.8±1	92.1
				Example 5	679±40	35.3±1.5	96.8
Example 6	622±50	31.1±2	108.9
				Example 9	580±50	25±1.5	115
Example 12	450±30	16±1	125
				Example 18	600±30	28±2	113
Example 21	415±30	15±1.5	123
				Control sample	717±20	34.9±3	80.7
Comparative example 1	580±30	26.9±1	78.2
				Comparative example 2	610±20	28±1.5	81
Comparison ofExample 3	490±60	19.5±1	104.6
				Comparative example 4	510±40	21±0.5	106
Comparative example 7	280±60	10±1	98
				Comparative example 8	320±50	12±0.5	99

It can be seen from table 1 that the comparative examples 1, 3, 7, to which only 5 wt%, 10 wt%, 30 wt% alkali lignin was added, respectively, show a decrease in both elongation at break and tensile strength relative to the pure PBAT blank control; compared with a comparative example, after the cellulose and the metal coordination bond auxiliary agent, the antioxidant and the plasticizer are introduced into the composite material, the tensile property and the elongation at break of the composite material are obviously improved. Example 2 has 31% and 19% increase in tensile strength and elongation at break, respectively, and 10% increase in elastic modulus at 5% strain, as compared to comparative example 1. Example 3 has a 19% and 16% increase in tensile strength and elongation at break, respectively, and an 18% increase in elastic modulus at 5% strain, as compared to comparative example 1. Example 5 has a 68% and 33% increase in tensile strength and elongation at break, respectively, compared to comparative example 4, but a 8% decrease in elastic modulus at 5% strain. Example 6 has 48% and 22% increase in tensile strength and elongation at break, respectively, and 3% increase in elastic modulus at 5% strain, as compared to comparative example 4. Example 12 has a 33% and 41% increase in tensile strength and elongation at break, respectively, and a 26% increase in elastic modulus at 5% strain, as compared to comparative example 8. Example 21 has 25% and 30% increase in tensile strength and elongation at break, respectively, and 24% increase in elastic modulus at 5% strain, as compared to comparative example 8.

The lignin/PBAT composite plastic sheets of examples and comparative examples were tested for water contact angle data using a static contact angle tester, and the results are shown in table 2.

TABLE 2 static contact Angle test results for part of the samples

Sample (I)	Static contact angle/degree of water
		Example 2	101.7
Example 5	99
		Example 6	97
Example 9	86
		Example 12	81
Example 21	87
		Control sample	113.1
Comparative example 1	99.7
		Comparative example 3	92.6
Comparative example 4	92.6
		Comparative example 7	86.9

It can be seen from table 2 that the static contact angle of water is reduced to different degrees in comparative examples 1, 3, 7, where only 5 wt%, 10 wt%, 30 wt% alkali lignin is added, respectively, relative to the pure PBAT blank control. Compared with the comparative example, when the cellulose, the metal coordination bond auxiliary agent, the antioxidant and the plasticizer are introduced into the composite material, the static water contact angle of the composite material is obviously increased. Example 2 compared to comparative example 1, when nanocellulose, an antioxidant, a metal coordinate bond assistant, and a plasticizer were introduced into the composite material, the water static contact angle of the composite material increased by 2 °. Example 5 the static contact angle of water of the composite increased by 6 deg. when the cellulose and the metal coordination bond assistant were introduced into the composite, compared to comparative example 4. The introduction of the metal coordination bond assistant is mainly benefited, so that the hydrophilic group in the composite material reacts with an epoxy group or forms a metal coordination bond in the presence of metal ions, the interface bonding is tighter, and the hydrophilicity is weakened.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.