A photothermal conversion controllable degradable fully degradable composition, a fully degradable mulching film and a preparation method thereof

Abstract

The application discloses a kind of photothermal conversion controllable degradation full-degradable composition, full-degradable mulch and preparation method thereof, belong to degradable mulch technical field, the full-degradable composition with full-degradable resin PBAT and PLA as main component, add controllable degradable agent that PCL and metal ion type degradation accelerator are compounded according to certain mass ratio, and photothermal conversion agent based on graphene, can effectively control the film breaking time of mulch prepared by full-degradable composition is 4~9 months, and has higher photothermal conversion efficiency.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of degradable mulching film, and particularly relates to a light-heat conversion type controllable degradation full-degradable composition, a full-degradable mulching film and a preparation method thereof. BACKGROUND

[0002] With the advancement of agricultural modernization, agricultural mulching film plays an important role in heat preservation, soil moisture preservation and weed suppression. However, traditional PE mulching film is difficult to degrade in the natural environment, and long-term use will cause soil structure damage and "white pollution", which seriously threatens the ecological environment. Therefore, full-degradable resin mulching film as a replacement solution has gradually attracted attention and has begun to be widely used in agricultural production.

[0003] Although the full-degradable resin mulching film has environmental friendliness, the prior art still has obvious disadvantages. Firstly, the degradation period is uncontrollable: the full-degradable mulching film on the market at present mostly uses PLA, PBAT and other materials, and its degradation period is fixed, which is difficult to accurately control the film breaking time according to the growth period of different crops (such as short-term leafy vegetables and long-term melons and fruits), and too early film breaking will lose the effect of heat and moisture preservation, and too late film breaking will easily entangle the crop root system; secondly, the light-heat conversion efficiency is low: in cold areas and winter planting, the mulching film with weak light-heat conversion capacity cannot effectively absorb solar energy to convert into heat energy, thereby making the temperature under the film low, resulting in slow germination and poor growth of crops.

[0004] Therefore, it is urgent to develop a full-degradable mulching film material which can accurately control the film breaking time in 4-9 months and has high light-heat conversion efficiency, so as to meet the dual demands of environmental friendliness and functionality in modern agriculture. SUMMARY

[0005] In view of the above disadvantages in the prior art, a light-heat conversion type controllable degradation full-degradable composition, a full-degradable mulching film and a preparation method thereof are provided. The full-degradable composition is prepared by adding a controllable degradation agent composed of polycaprolactone and a metal ion type degradation promoter in a certain mass ratio to a full-degradable resin as a main component, and a light-heat conversion agent based on graphene. The film breaking time of the mulching film prepared from the full-degradable composition can be effectively controlled in 4-9 months, and the mulching film has high light-heat conversion efficiency.

[0006] The light-heat conversion type controllable degradation full-degradable composition comprises, by weight, 60-100 parts of full-degradable resin, 0.3-3 parts of light-heat conversion agent, 2-8 parts of controllable degradation agent and 0.1-10 parts of other additives.

[0007] The full-degradable resin comprises polybutylene adipate terephthalate (PBAT) and polylactic acid (PLA) in a mass ratio of (2-4):1.

[0008] The photo-thermal conversion agent comprises at least one of graphene, graphene oxide and doped graphene.

[0009] The controllable degradable agent comprises polycaprolactone (PCL) and a metal ion type degradation promoter in a mass ratio of 5-8:1, and the metal ion type degradation promoter comprises at least one of iron stearate and zinc stearate.

[0010] For the photo-thermal conversion type controllable degradable full-degradable composition, the PBAT in the main resin has excellent flexibility and degradability, and the PLA has high mechanical strength, and the two are mixed in a mass ratio of 2-4:1, so that the mechanical properties and full-degradable characteristics of the mulch film can be balanced, the mulch film is not easy to break during use, and the mulch film can be fully degraded after being discarded; the graphene in the photo-thermal conversion agent has good compatibility with the full-degradable resin, the unique two-dimensional structure can efficiently absorb visible light and near-infrared light in sunlight, has high photo-thermal conversion efficiency, and can significantly increase the temperature in the mulch film; the PCL in the controllable degradable agent has controllable degradable characteristics, interacts with metal ions (iron ions and zinc ions), and realizes precise regulation of the degradation period by adjusting the addition amount: when the addition amount is low (2-4 parts), the degradation rate is slowed down, the film breaking time is extended to 7-9 months, and the film is suitable for long-term crops; when the addition amount is high (4.5-8 parts), the resin chain is accelerated, and the film breaking time is shortened to 4-6 months, meeting the needs of short-term crops.

[0011] In some embodiments of the present application, the polybutylene adipate terephthalate has a melt index of 3-10 g / 10 min at 190℃ under a load of 2.16 kg.

[0012] In some embodiments of the present application, the polylactic acid has a melt index of 2-8 g / 10 min at 230℃ under a load of 2.16 kg.

[0013] In some embodiments of the present application, the polycaprolactone has a melt index of 2-8 g / 10 min at 160℃ under a load of 2.16 kg.

[0014] In some embodiments of the present application, the photo-thermal conversion agent comprises doped graphene, and the doped graphene comprises at least one of boron-doped graphene, nitrogen-doped graphene and boron-nitrogen-doped graphene, preferably nitrogen-doped graphene, and more preferably boron-nitrogen-doped graphene.

[0015] In some embodiments of the present application, the boron-doped graphene is prepared from a boron source and graphene, and the ratio of the amount of substance of boron atoms in the boron source to the amount of substance of carbon atoms in the graphene is 1:1-5.

[0016] In some embodiments of the present application, the raw material for preparing the nitrogen-doped graphene comprises a nitrogen source and graphene, and the ratio of the amount of substance of nitrogen atoms in the nitrogen source to the amount of substance of carbon atoms in the graphene is 1:1-5.

[0017] In some embodiments of the present application, the raw material for preparing the boron-nitrogen-doped graphene comprises a boron source, a nitrogen source and graphene, and the ratio of the amount of substance of boron atoms in the boron source, the amount of substance of nitrogen atoms in the nitrogen source and the amount of substance of carbon atoms in the graphene is 1:1-2:1-10.

[0018] In some embodiments of the present application, the boron source comprises at least one of boric acid, triisopropyl borate and boron nitride.

[0019] In some embodiments of the present application, the nitrogen source comprises at least one of urea, melamine, polyaniline, polyacrylonitrile and boron nitride.

[0020] In some embodiments of the present application, the other auxiliary agent comprises at least one of a compatibilizer, an antioxidant, a light stabilizer and a lubricant.

[0021] In some embodiments of the present application, the compatibilizer comprises maleic anhydride grafted polylactic acid.

[0022] In some embodiments of the present application, the amount of the compatibilizer is 1-5 parts.

[0023] In some embodiments of the present application, the antioxidant comprises at least one of antioxidant 1010 and antioxidant 1076.

[0024] In some embodiments of the present application, the amount of the antioxidant is 0.1-1 part.

[0025] In some embodiments of the present application, the light stabilizer comprises at least one of salicylate, benzophenone, benzotriazole and triazine.

[0026] In some embodiments of the present application, the amount of the light stabilizer is 0.1-1 part.

[0027] In some embodiments of the present application, the lubricant comprises at least one of ethylene bis-stearamide, hydroxyethyl ethylene bis-stearamide and oleic acid amide.

[0028] In some embodiments of the present application, the amount of the lubricant is 0.5-5 parts.

[0029] Another object of the present application is to provide a preparation method of the above-mentioned photo-thermal conversion controllable degradable fully degradable composition, which comprises the following steps:

[0030] (1) drying the fully degradable resin for standby;

[0031] (2) mixing the light-heat conversion agent with part of other auxiliary agents, ultrasonic pre-dispersing to obtain a pre-dispersed body;

[0032] (3) mixing the dried full-degradable resin, the pre-dispersed body, the controllable degradable agent and the rest of other auxiliary agents uniformly to obtain the light-heat conversion type controllable degradable full-degradable composition.

[0033] In some embodiments of the present application, the drying treatment in step (1) is performed at a temperature of 60-80℃ for 4-6h.

[0034] In some embodiments of the present application, the part of other auxiliary agents in step (2) comprises a compatibilizer.

[0035] In some embodiments of the present application, the ultrasonic in step (2) is performed at a power of 300-500W for 20-40min.

[0036] In some embodiments of the present application, the mixing in step (3) is performed by a high-speed mixer at a temperature of 70-90℃, a stirring speed of 800-1200r / min and for 15-25min.

[0037] Another object of the present application is to provide a light-heat conversion type controllable degradable full-degradable mulching film comprising the light-heat conversion type controllable degradable full-degradable composition.

[0038] In some embodiments of the present application, the light-heat conversion type controllable degradable full-degradable mulching film has a thickness of 5-100μm.

[0039] Still another object of the present application is to provide a preparation method of the light-heat conversion type controllable degradable full-degradable mulching film.

[0040] (a) adding the light-heat conversion type controllable degradable full-degradable composition into a twin-screw extruder to perform extrusion granulation to obtain a functional masterbatch;

[0041] (b) adding the functional masterbatch into a casting machine to perform casting molding to obtain the light-heat conversion type controllable degradable full-degradable mulching film.

[0042] In some embodiments of the present application, the temperature of each section of the extruder in step (a) is 140-170℃, and the screw rotation speed is 35-55r / min.

[0043] In some embodiments of the present application, the temperature of the feeding section of the extruder in step (a) is 140-150℃, the temperature of the compression section is 150-160℃, and the temperature of the homogenization section is 160-170℃.

[0044] In some embodiments of the present application, the temperature of the barrel of the casting machine in step (b) is 150-175 DEG C, the temperature of the die is 160-180 DEG C, the temperature of the cooling roller is 25-40 DEG C, and the pulling speed is 8-15 m / min.

[0045] Compared with the prior art, the present application has the following beneficial effects:

[0046] 1、The raw materials in the present application are all fully degradable or environmentally friendly components, which can be completely degraded within 12 months without soil residual pollution, and the preparation process is simple and suitable for large-scale industrial production.

[0047] 2、In the present application, by adjusting the compounding ratio and adding amount of the controllable degradable agent, the film breaking time of the mulch film can be accurately controlled for 4-9 months, perfectly matching the growth period of different crops, and avoiding premature failure or too late winding of the root system.

[0048] 3、The use of light-heat conversion agent in the present application can effectively improve the light-heat conversion efficiency of the mulch film, greatly increase the temperature in the mulch film, effectively make up for the lack of environmental heat source, and significantly promote the growth of crops, which has very high popularization value in agricultural planting in cold regions. BRIEF DESCRIPTION OF DRAWINGS

[0049] Figure 1 Temperature-time graph in the light-heat conversion performance test of the fully degradable mulch film obtained by the present application. DETAILED DESCRIPTION

[0050] In order to enable the personnel in the technical field to better understand the technical solutions in the present application, the technical solutions of the present application will be described clearly and completely in combination with the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by the personnel in the field without creative labor should belong to the protection scope of the present application.

[0051] All raw materials in the present application have no special description, which are all from the market.

[0052] The raw materials used in the following preparation examples and embodiments are as follows:

[0053] PBAT: THJS-7801 of Xinjiang Lanshan Tunhe, the melt index under 190 DEG C and 2.16 kg is 5.0 g / 10 min;

[0054] PLA: J9503J of Japan Mitsubishi, the melt index under 230 DEG C and 2.16 kg is 3.0 g / 10 min;

[0055] Graphene and graphene oxide: powder of Anhui Nanhu Electronics Technology;

[0056] PCL: Capa™ 6800 from Perstorp, Sweden, melt index at 160°C, 2.16 kg, 3.0 g / 10 min;

[0057] Compatibilizer: Maleic anhydride grafted polylactic acid grafting agent from Jiangmen Zhonglian Plastic Science and Technology Co., Ltd.

[0058] Antioxidant: Antioxidant 1076;

[0059] Light stabilizer: phenyl salicylate;

[0060] Lubricant: ethylene bis-stearamide (EBS).

[0061] Preparation Example 1

[0062] The present preparation example provides boron-doped graphene, and a preparation method thereof includes the following steps:

[0063] 0.015 mol of H3BO3 was added to 100 mL of a water dispersion of graphene (3 mg / mL), and ultrasonic treatment was performed for 15 min. The dispersion was transferred to a high-pressure reaction kettle, and a hydrothermal doping reaction was performed at 180°C for 12 hours to obtain a boron-doped graphene hydrogel. The boron-doped graphene hydrogel was washed with water and freeze-dried to obtain boron-doped graphene.

[0064] Preparation Example 2

[0065] The present preparation example provides nitrogen-doped graphene, and a preparation method thereof includes the following steps:

[0066] 0.0075 mol of urea was added to 100 mL of a water dispersion of graphene (3 mg / mL), and ultrasonic treatment was performed for 15 min. The dispersion was transferred to a high-pressure reaction kettle, and a hydrothermal doping reaction was performed at 180°C for 12 hours to obtain a boron-doped graphene hydrogel. The boron-doped graphene hydrogel was washed with water and freeze-dried to obtain nitrogen-doped graphene.

[0067] Preparation Example 3

[0068] The present preparation example provides boron-nitrogen-doped graphene, and a preparation method thereof includes the following steps:

[0069] 0.0075 mol of BN was added to 100 mL of a water dispersion of graphene (3 mg / mL), and ultrasonic treatment was performed for 15 min. The dispersion was transferred to a high-pressure reaction kettle, and a hydrothermal doping reaction was performed at 180°C for 12 hours to obtain a boron-doped graphene hydrogel. The boron-doped graphene hydrogel was washed with water and freeze-dried to obtain boron-nitrogen-doped graphene.

[0070] Example 1

[0071] The embodiment provides a photothermal conversion type controllable degradation full-degradable mulch and a preparation method thereof, and the preparation raw materials are as follows in terms of weight parts: 60 parts of PBTA, 20 parts of PLA, 1.8 parts of graphene, 2 parts of PCL, 0.3 parts of iron stearate, 4 parts of a compatibilizer, 0.3 parts of an antioxidant, 0.5 parts of a light stabilizer and 1.8 parts of a lubricant.

[0072] The preparation method comprises the following steps:

[0073] S1, preparing a full-degradable composition:

[0074] (1) PBTA and PLA are vacuum dried at 70 DEG C for 5h, and are reserved;

[0075] (2) graphene is mixed with a compatibilizer, and is ultrasonically dispersed at 400 W for 30 min to obtain a pre-dispersion;

[0076] (3) the dried PBTA and PLA are mixed with the pre-dispersion, PCL, iron stearate, an antioxidant, a light stabilizer and a lubricant, are put into a high-speed mixer, and are mixed at 80 DEG C and 1000 r / min for 20 min to obtain a full-degradable composition;

[0077] S2, preparing a full-degradable mulch:

[0078] (a) the full-degradable composition is added into a double-screw extruder, the feeding section of the double-screw extruder is at 145 DEG C, the compression section is at 155 DEG C, the homogenizing section is at 165 DEG C, the screw rotation speed is 45 r / min, and the full-degradable composition is extruded and granulated to obtain a functional masterbatch;

[0079] (b) the functional masterbatch is added into a casting machine, the barrel temperature of the casting machine is 160 DEG C, the die head temperature is 170 DEG C, the cooling roller temperature is 30 DEG C, the traction speed is 10 m / min, and the functional masterbatch is cast into a full-degradable mulch with a thickness of 10 mu m.

[0080] Embodiment 2

[0081] The embodiment provides a photothermal conversion type controllable degradation full-degradable mulch and a preparation method thereof, and the preparation raw materials are as follows in terms of weight parts: 50 parts of PBTA, 20 parts of PLA, 1 part of graphene, 6 parts of PCL, 0.8 parts of zinc stearate, 3.5 parts of a compatibilizer, 0.2 parts of an antioxidant, 0.4 parts of a light stabilizer and 1.5 parts of a lubricant.

[0082] The preparation method comprises the following steps:

[0083] S1, preparing a full-degradable composition:

[0084] (1) PBTA and PLA are vacuum dried at 75 DEG C for 5h, and are reserved;

[0085] (2) Mix graphene with compatibilizer, 400W ultrasonic dispersion for 25min, get pre-dispersion;

[0086] (3) Mix dried PBTA, PLA, pre-dispersion, PCL, iron stearate, antioxidant, light stabilizer, lubricant, put into high-speed mixer, mix at 80℃, 1000r / min for 18min, get fully degradable composition;

[0087] S2, prepare fully degradable mulch film:

[0088] (a) Put fully degradable composition into double screw extruder, double screw extruder feeding section 145℃, compression section 160℃, homogenization section 165℃, screw speed 35r / min, extrude and granulate, get functional masterbatch;

[0089] (b) Put functional masterbatch into casting machine, casting machine barrel temperature 165℃, die temperature 170℃, cooling roller temperature 30℃, pulling speed 12m / min, cast into 8μm thick fully degradable mulch film.

[0090] Example 3

[0091] The embodiment provides a photothermal conversion type controllable degradable fully degradable mulch film and a preparation method thereof, and the preparation raw materials are PBTA 40 parts, PLA 20 parts, graphene 1.4 parts, PCL 5 parts, zinc stearate 1 part, compatibilizer 4 parts, antioxidant 0.4 parts, light stabilizer 0.3 parts and lubricant 1 part by weight.

[0092] The preparation method comprises the following steps:

[0093] S1, prepare fully degradable composition:

[0094] (1) PBTA and PLA are vacuum dried at 60℃ for 5h, and are ready for use;

[0095] (2) Mix graphene with compatibilizer, 400W ultrasonic dispersion for 25min, get pre-dispersion;

[0096] (3) Mix dried PBTA, PLA, pre-dispersion, PCL, iron stearate, antioxidant, light stabilizer, lubricant, put into high-speed mixer, mix at 90℃, 1200r / min for 20min, get fully degradable composition.

[0097] S2, prepare fully degradable mulch film:

[0098] (a) The full-degradation composition is added to a twin-screw extruder, the feeding section of which is at 150°C, the compression section at 160°C, the homogenization section at 170°C, the screw rotation speed is 35 r / min, and the extrusion granulation is performed to obtain the functional masterbatch;

[0099] (b) The functional masterbatch is added to a casting machine, the barrel temperature of which is 170°C, the die temperature is 180°C, the cooling roller temperature is 30°C, the pulling speed is 10 m / min, and the casting molding is performed to obtain the full-degradation mulch film with a thickness of 10 μm.

[0100] Example 4

[0101] The present embodiment provides a photothermal conversion controllable degradation full-degradation mulch film and a preparation method thereof. The preparation raw materials are 80 parts of PBTA, 20 parts of PLA, 1.6 parts of graphene, 3 parts of PCL, 0.5 parts of iron stearate, 4 parts of a compatibilizer, 0.5 parts of an antioxidant, 0.2 parts of a light stabilizer, and 3 parts of a lubricant.

[0102] The preparation method comprises the following steps:

[0103] S1, preparing a full-degradation composition:

[0104] (1) The PBTA and PLA are vacuum dried at 80°C for 6 h and are ready for use;

[0105] (2) The graphene is mixed with the compatibilizer, and is ultrasonically dispersed at 400 W for 25 min to obtain a pre-dispersion;

[0106] (3) The dried PBTA and PLA are mixed with the pre-dispersion, PCL, iron stearate, antioxidant, light stabilizer, and lubricant, and are placed into a high-speed mixer, mixed at 70°C and 800 r / min for 20 min to obtain the full-degradation composition.

[0107] S2, preparing a full-degradation mulch film:

[0108] (a) The full-degradation composition is added to a twin-screw extruder, the feeding section of which is at 140°C, the compression section at 150°C, the homogenization section at 160°C, the screw rotation speed is 40 r / min, and the extrusion granulation is performed to obtain the functional masterbatch;

[0109] (b) The functional masterbatch is added to a casting machine, the barrel temperature of which is 150°C, the die temperature is 160°C, the cooling roller temperature is 25°C, the pulling speed is 10 m / min, and the casting molding is performed to obtain the full-degradation mulch film with a thickness of 8 μm.

[0110] Example 5

[0111] The embodiment provides a photothermal conversion controllable degradation full-degradable mulch film and a preparation method thereof, which are different from the embodiment 1 only in that graphene oxide is used to replace graphene in the embodiment 1, and the corresponding preparation method is adjusted accordingly, and the other parts are consistent with the embodiment 1.

[0112] Embodiment 6

[0113] The embodiment provides a photothermal conversion controllable degradation full-degradable mulch film and a preparation method thereof, which are different from the embodiment 1 only in that the boron-doped graphene in the preparation example 1 is used to replace graphene in the embodiment 1, and the corresponding preparation method is adjusted accordingly, and the other parts are consistent with the embodiment 1.

[0114] Embodiment 7

[0115] The embodiment provides a photothermal conversion controllable degradation full-degradable mulch film and a preparation method thereof, which are different from the embodiment 1 only in that the nitrogen-doped graphene in the preparation example 2 is used to replace graphene in the embodiment 1, and the corresponding preparation method is adjusted accordingly, and the other parts are consistent with the embodiment 1.

[0116] Embodiment 8

[0117] The embodiment provides a photothermal conversion controllable degradation full-degradable mulch film and a preparation method thereof, which are different from the embodiment 1 only in that the boron-nitrogen-doped graphene in the preparation example 3 is used to replace graphene in the embodiment 1, and the corresponding preparation method is adjusted accordingly, and the other parts are consistent with the embodiment 1.

[0118] Performance test:

[0119] 1, mechanical property

[0120] According to GB / T 1040.3-2006, the full-degradable mulch films obtained in the embodiments 1-8 are cut into Type2 sample strips with a width of 25mm, and the mechanical properties (transverse direction) of the sample strips are tested at a test rate of 500mm / min, and the average value of three tests is taken, and the results are shown in Table 1.

[0121] 2, degradation period

[0122] The full-degradable mulch films obtained in the embodiments 1-8 (with a size of 1.5m*20m) are placed in a vegetable field in the north of Hubei province from September 15, 2024, every half month, whether the mulch film appears natural film breaking phenomenon is observed, the time when the natural film breaking phenomenon appears is recorded as the film breaking time, and the observation is continued until the “white” mulch film cannot be observed, and the time is recorded as the complete degradation time. The results are shown in Table 1.

[0123] 3, photothermal conversion performance

[0124] In an indoor environment with a temperature of 10℃, half the height of farmland soil was filled into an open, upward-facing acrylic box (20cm×10cm×10cm). An electronic thermometer was placed on the soil surface. The opening of the acrylic box was covered with the fully degradable mulch film described in Examples 1-8. Then, a 500W xenon lamp was used to vertically irradiate the film surface at a height of 1.5m for 1 hour. Irradiation was then stopped, and the temperature inside the acrylic box was recorded at different time points to obtain temperature-time curves. The results are as follows. Figure 1 As shown.

[0125] Table 1

[0126]

[0127] As shown in Table 1, the fully degradable mulch films obtained in Examples 1-8 of this invention possess good mechanical properties and a controllable degradation cycle. The film breaking time can be effectively controlled within 4-9 months and the complete degradation time within 12 months by adjusting the amount of the controllable degradation agent, which is a mixture of polycaprolactone and a metal ion-type degradation promoter in a certain mass ratio. Simultaneously, from... Figure 1 It is known that the fully degradable mulch film obtained in Examples 1-8 of the present invention also has good photothermal conversion performance. In a cold environment of 10°C, it can effectively increase the temperature inside the film to above 15°C, and can maintain the temperature inside the film in a high range after the light is stopped. Furthermore, when nitrogen-doped graphene is used as a photothermal conversion agent, especially boron-nitrogen-doped graphene, the obtained fully degradable mulch film has better photothermal conversion efficiency, and the temperature inside the film can reach above 20°C, which is particularly suitable for the planting of crops in cold regions.

[0128] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that after reading this application specification, they can still modify or make equivalent substitutions to the specific implementation of the present invention, but these modifications or changes do not depart from the protection scope of the pending claims of the present invention.

Claims

1. A photothermal conversion type controllable degradable fully degradable composition, characterized in that, comprising 60-100 parts by weight of the fully degradable resin, 0.3-3 parts by weight of the light-heat conversion agent, 2-8 parts by weight of the controllable degradable agent, and 0.1-10 parts by weight of other additives; the fully degradable resin comprises polybutylene adipate terephthalate and polylactic acid at a mass ratio of (2-4):1; the light-heat conversion agent comprises doped graphene; the doped graphene comprises nitrogen-doped graphene; the controllable degradable agent comprises polycaprolactone and a metal ion type degradation promoter at a mass ratio of (5-8):1, and the metal ion type degradation promoter comprises at least one of iron stearate and zinc stearate.

2. The fully degradable composition of claim 1, wherein, the nitrogen-doped graphene is prepared from a nitrogen source and graphene, and the ratio of the amount of substance of nitrogen atoms in the nitrogen source to the amount of substance of carbon atoms in the graphene is 1:1-5.

3. A photothermally converting controllably degradable fully degradable composition, characterized in that, comprising 60-100 parts by weight of the fully degradable resin, 0.3-3 parts by weight of the light-heat conversion agent, 2-8 parts by weight of the controllable degradable agent, and 0.1-10 parts by weight of other additives; the fully degradable resin comprises polybutylene adipate terephthalate and polylactic acid at a mass ratio of (2-4):1; the light-heat conversion agent comprises doped graphene; the doped graphene comprises boron-nitrogen-doped graphene; the controllable degradable agent comprises polycaprolactone and a metal ion type degradation promoter at a mass ratio of (5-8):1, and the metal ion type degradation promoter comprises at least one of iron stearate and zinc stearate.

4. The fully degradable composition of claim 3, wherein, the boron-nitrogen-doped graphene is prepared from a boron source, a nitrogen source and graphene, and the ratio of the amount of substance of boron atoms in the boron source, the amount of substance of nitrogen atoms in the nitrogen source and the amount of substance of carbon atoms in the graphene is 1:1-2:1-10.

5. The fully degradable composition according to any one of claims 1 to 4, wherein, the polybutylene adipate terephthalate has a melt index of 3-10 g / 10 min at 190°C under a load of 2.16 kg; and / or, the polylactic acid has a melt index of 2-8 g / 10 min at 230°C under a load of 2.16 kg; and / or, the polycaprolactone has a melt index of 2-8 g / 10 min at 160°C under a load of 2.16 kg.

6. The fully degradable composition according to any one of claims 1 to 4, wherein, the other additives comprise at least one of a compatibilizer, an antioxidant, a light stabilizer and a lubricant.

7. A process for the preparation of the fully degradable composition according to any one of claims 1 to 6, characterized in that, comprising the following steps: (1) drying the fully degradable resin for standby; (2) mixing the light-heat conversion agent with part of the other additives, ultrasonic pre-dispersing to obtain a pre-dispersion; (3) mixing the dried fully degradable resin, the pre-dispersion, the controllable degradable agent and the remaining other additives uniformly to obtain a fully degradable composition.

8. A photothermal conversion controllable degradable full-degradable mulching film, characterized in that, comprising the fully degradable composition of any one of claims 1-6.

9. The method of claim 8, wherein the fully degradable mulch film is prepared by the steps of: comprising the following steps: (a) adding the fully degradable composition of any one of claims 1-6 into a twin-screw extruder, extruding and granulating to obtain a functional masterbatch; (b) adding the functional masterbatch into a casting machine, casting and forming to obtain a fully degradable mulch film.

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