A photothermal type dark degradable paper mulch and a preparation method thereof
By preparing dark-colored biodegradable paper mulch, using lignite powder and alkaline substances to prepare dark-colored wood pulp fibers and impregnating them with cross-linking resin, the problems of insufficient photothermal performance and environmentally friendly dyeing of traditional paper mulch are solved, realizing the comprehensive agronomic value of high-strength protection, degradation and soil improvement.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- QILU UNIVERSITY OF TECHNOLOGY (SHANDONG ACADEMY OF SCIENCES)
- Filing Date
- 2026-01-30
- Publication Date
- 2026-05-29
AI Technical Summary
Traditional paper mulch film has insufficient light and heat performance, limited functions, and existing dyeing methods are not environmentally friendly and may have adverse effects on soil microorganisms.
Dark wood pulp fibers are prepared by mixing lignite powder with alkaline substances, and then dark base paper is made through a wet papermaking process. The paper is then impregnated with water-based resin for cross-linking and curing. Combined with the condensation active compounds in the lignite extract, photothermal properties and biodegradability are achieved.
It offers excellent photothermal heating performance, mechanical strength, weed suppression effect and soil improvement potential, achieves complete biodegradability, avoids plastic residue, and conforms to the green concept of all-bio-based materials.
Smart Images
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Abstract
Description
Technical Field
[0001] This invention relates to the field of mulch film production, specifically to a photothermal type dark-colored biodegradable paper mulch film and its preparation method. Background Technology
[0002] Traditional plastic mulch films (especially polyethylene mulch films) are widely used in modern agricultural production due to their significant heat retention, moisture retention, and weed suppression effects. However, their non-degradable nature results in large amounts of mulch film residue remaining in the soil, creating serious "white pollution," damaging soil structure, affecting crop root growth, and potentially posing ecological risks through the food chain. Therefore, developing environmentally friendly, fully biodegradable alternative materials has become an urgent issue in the field of sustainable agricultural development.
[0003] Currently, biodegradable mulch films are mainly divided into two categories: bio-based biodegradable plastics (such as polylactic acid PLA and polyhydroxyalkanoates PHA) and natural fiber-based mulch films (such as paper mulch films). Bio-based biodegradable plastics often suffer from high costs, mismatch between mechanical properties and agronomic requirements, and harsh and uncertain degradation conditions in natural soil environments. In contrast, paper mulch films made from plant fibers (such as straw and wood pulp) have inherent advantages such as renewable raw materials, complete biodegradability in soil and conversion into humus, and relatively mature production processes. However, ordinary paper mulch films face problems in practical application, including insufficient light and heat performance and limited functionality. Traditional paper mulch films are light-colored, with high reflectivity and low absorption of sunlight, resulting in a much lower effect on raising soil temperature compared to black plastic mulch films. Secondly, while ordinary paper mulch films mainly rely on physical mulching to suppress weeds, their light transmittance may still promote the germination of some weeds. Furthermore, they lack additional soil improvement or nutrient slow-release functions, and their overall agronomic value needs to be improved. To enhance the photothermal performance of paper mulch films, existing technologies typically employ dyeing methods involving the addition of carbon black or synthetic dyes. However, carbon black originates from fossil fuels, which contradicts the green concept of a fully bio-based mulch film; while synthetic dyes may introduce environmental risks such as heavy metals, and their degradation products may have unknown impacts on soil microbial communities. Summary of the Invention
[0004] The technical objective of this invention is to address the shortcomings of the prior art by providing a photothermal dark-colored biodegradable paper mulch film that can fully utilize lignite to achieve high-strength protection in the early stage and degradation in the middle stage of the paper mulch film.
[0005] The technical objective of this invention is achieved as follows: a photothermal type dark-colored biodegradable paper mulch film, the preparation method of which includes: S1. Lignite powder, alkaline substances and appropriate amount of water are mixed, heated and stirred, and then separated into solid and liquid to obtain solid lignite slag and lignite extract. S2. Solid lignite slag is mixed with an appropriate amount of wood pulp, water, and retention and filtration aids, and stirred thoroughly to obtain dark wood pulp fibers filled with lignite slag; S3. Dark wood pulp fibers are processed using a wet papermaking process to obtain dark base paper; S4. Add an appropriate amount of polycondensation active compound to lignite extract, heat and stir to obtain an impregnation water-based resin, wherein the polycondensation active compound is an aldehyde compound, an amine compound and / or a polyol compound; S5. Dark-colored base paper is impregnated with water-based resin and then dried, allowing the resin to cross-link and cure during the paper drying process, resulting in a photothermal dark-colored biodegradable paper film.
[0006] As described above, this invention uses lignite alkali extract as filler and dye to provide photothermal properties for paper mulch film; it achieves high-strength protection of paper mulch film in the early stage through water-based resin impregnation, and utilizes the bioactivity of humic acid in lignite to synergistically promote the degradation of plant fibers in the middle and late stages, thus achieving complete biodegradability of the material. It has excellent photothermal heating performance, mechanical strength, weed suppression effect, soil improvement potential and full biodegradability characteristics.
[0007] Preferably, the alkaline substance in step S1 is potassium hydroxide, sodium hydroxide, sodium carbonate, and / or ammonia.
[0008] Preferably, the amount of alkaline substance added in step S1 is 8% to 12% of the mass of lignite powder, and more preferably 9% to 11%.
[0009] Preferably, the amount of water added in step S1 is 2 to 3 times the mass of lignite powder, and more preferably 2 to 2.5 times.
[0010] Preferably, the heating temperature in step S1 is 70~100℃, and more preferably 75~85℃.
[0011] Preferably, the heating and stirring time in step S1 is 20-60 min, and more preferably 30-40 min.
[0012] Preferably, in step S2, wood pulp is mixed with solid lignite slag, water is added until the solids concentration reaches 8%~12%, and after stirring evenly, a retention aid and filter aid are added to the mixed slurry.
[0013] Preferably, the mass ratio of wood pulp to solid lignite slag in step S2 is 10:2 to 10:3. The wood pulp can be any type of commercial wood pulp, such as commercial chemical pulp, straw pulp, waste paper pulp, etc.
[0014] Preferably, the retention and filtration aid mentioned in step S2 is an organic polymeric flocculant, which can be at least one of cationic polymers, anionic polymers, zwitterionic polymers, or nonionic polymers; preferably, it is cationic polyacrylamide.
[0015] Preferably, the amount of retention and filtration aid used in step S2 is 0.01%-0.2% of the oven-dry pulp mass, and more preferably 0.05%-0.1%.
[0016] Preferably, step S3 uses a wet papermaking process to obtain dark-colored base paper with a g / m² of 40~120 g / m². Dark-colored base paper is particularly preferred to have a g / m² of 50~80 g / m².
[0017] Preferably, the aldehyde compound in step S4 is at least one of formaldehyde, acetaldehyde, propionaldehyde, glyoxal, glutaraldehyde, and furfural, and more preferably formaldehyde, glyoxal, and / or glutaraldehyde.
[0018] Preferably, the amine compound in step S4 is at least one of urea, ethylenediamine, diethylenetriamine, triethylenetetramine, hexanediamine, aniline, and ethanolamine, with urea and ethylenediamine being the most preferred.
[0019] Preferably, the polyol compound in step S4 is at least one of ethylene glycol, propylene glycol, glycerol, pentaerythritol, polyethylene glycol, and sorbitol, with glycerol and polyethylene glycol being the most preferred.
[0020] Preferably, in step S4, the mass ratio of lignite extract solids to polycondensation active compound is 1:0.2 to 1:1.0, and particularly preferably 1:0.2 to 1:0.8.
[0021] Preferably, in step S4, the mass ratio of lignite extract solids to aldehydes, amines, and polyols is 1:(0~0.35):(0~0.25):(0~0.35), and the masses of aldehydes, amines, and polyols are not simultaneously zero.
[0022] Preferably, in step S4, the mass ratio of lignite extract solids to aldehydes, amines, and polyols is 1:(0.15~0.35):(0.10~0.25):(0.05~0.35), and particularly preferably 1:(0.20~0.30):(0.10~0.15):(0.05~0.30).
[0023] Preferably, aldehydes and amines can be added to the lignite extract at the same time, with the mass ratio of aldehydes to amines being 10:1 to 10:3.
[0024] Preferably, the heating temperature in step S4 is 60~90℃, and more preferably 80~90℃; Preferably, in step S4, the reaction is stopped when the rotational viscosity reaches 100-400 mPa·s. This viscosity range is the target range for the waterborne resin of this invention. Below 100 mPa·s, the reaction system is in the prepolymerization stage, and above 400 mPa·s, gelation is likely to occur. Furthermore, to achieve the best impregnation and curing effect, it is particularly preferred to stop the reaction when the rotational viscosity reaches 300-400 mPa·s, and the reaction time is usually 50-70 minutes.
[0025] Preferably, in step S5, the base paper passes through the water-based resin at a speed of 200-600 m / s, and the amount of dry base resin absorbed by the base paper is 2-14 g / m², based on the amount of dry base resin in the water-based resin used for impregnation. 2 The preferred speed of the base paper is 400-500 m / s, and the preferred absorption of dry resin by the base paper is 6-10 g / m. 2 .
[0026] Preferably, the drying temperature in step S5 is 100~140℃, and more preferably 130~140℃.
[0027] A further technical objective of this invention is to provide a method for preparing the above-mentioned photothermal type dark-colored biodegradable paper mulch film.
[0028] Compared with the prior art, the photothermal dark-colored biodegradable paper mulch film and its preparation method of the present invention have the following outstanding advantages: (i) Lignite itself is dark black in color and has a wide range of strong absorption capabilities in the visible to near-infrared bands. This invention uses lignite alkali extract as filler and dye to give paper mulch film excellent light absorption and heat-increasing properties. (ii) This invention combines soft lignite with plant fibers through impregnation to obtain a uniform, stable paper mulch film with strength that meets the requirements for mulching, thus achieving high-strength protection in the early stage of paper mulch film. (III) This invention utilizes the bioactivity of humic acid in lignite to synergistically promote the degradation of plant fibers in the middle and late stages, thereby achieving complete biodegradation of the material and eliminating plastic residues. (iv) This invention realizes the full material utilization of lignite. As a low-rank coal, lignite is abundant and inexpensive. It has a natural dark brown color, a porous structure, and is rich in humic acid, which can improve soil aggregate structure, enhance fertilizer and water retention capacity, and stimulate crop growth. Detailed Implementation
[0029] The following detailed description of the photothermal dark-colored biodegradable paper mulch film and its preparation method according to specific embodiments of the present invention is provided below.
[0030] Example 1 The preparation steps for the photothermal type dark-colored biodegradable paper mulch film in this embodiment are as follows: S1. Grind the raw lignite and pass it through a 200-mesh sieve to obtain lignite powder. Add potassium hydroxide (10% by weight of lignite powder) and water (twice the weight of lignite powder) to the lignite powder, heat to 80 ℃, and stir for alkali extraction for 30 min. Filter through a 300-mesh sieve to obtain solid lignite slag and liquid dark lignite extract.
[0031] S2. A mixture of 50% bleached hardwood pulp and 50% straw pulp plant fibers is mixed with lignite cinder at a mass ratio of 10:2. Water is added to adjust the solids concentration to 10%, and the mixture is stirred until homogeneous. 0.05% cationic polyacrylamide by weight of oven-dry pulp is added and stirred until homogeneous to obtain dark wood pulp fibers filled with lignite cinder.
[0032] S3. The added wood pulp is processed, pressed and dried according to the papermaking method of GB / T 24325-2009 standard to obtain dark-colored base paper with a basis weight of 60 grams.
[0033] S4. Formaldehyde, urea, and glycerol, active compounds, were added to the lignite extract. The mass ratio of the lignite extract solids to the active compounds formaldehyde, urea, and glycerol was 1:0.25:0.10:0.05. The liquid was heated to 80°C, and the reaction was stopped when the viscosity reached 350 mPa·s (approximately 56 min), yielding a dark-colored water-based resin for paper impregnation.
[0034] S5. The base paper passes through the water-based resin at a speed of 400 m / s, absorbing the resin, and then the dry resin is removed by roller extrusion. By adjusting the concentration of the water-based resin and the pressure of the roller extrusion, the absorption of dry resin by the paper is maintained at 8 g / m². 2 After being impregnated, the paper is dried in a 130°C drying zone. During the drying process, the resin undergoes cross-linking and curing, becoming insoluble and infusible, resulting in a photothermal, dark-colored, biodegradable paper film.
[0035] Example 2 The preparation steps for the photothermal type dark-colored biodegradable paper mulch film in this embodiment are as follows: S1. Grind the raw lignite and pass it through a 200-mesh sieve to obtain lignite powder. Add 10% potassium hydroxide to the lignite powder, add water with twice the mass of the lignite powder, heat to 100 ℃, and stir for alkali extraction for 60 min. Filter through a 300-mesh sieve to obtain solid lignite slag and liquid dark lignite extract.
[0036] S2. Commercial bleached hardwood pulp and lignite ash are mixed at a mass ratio of 10:2. Water is added to adjust the solids concentration to 2%, and the mixture is stirred evenly. 0.05% cationic polyacrylamide by weight of oven-dried pulp is added and stirred evenly to obtain dark wood pulp fibers filled with lignite ash.
[0037] S3. The added wood pulp is processed, pressed and dried according to the papermaking method of GB / T 24325-2009 standard to obtain dark-colored base paper with a basis weight of 50 grams.
[0038] S4. Glyoxal and urea, active compounds, were added to the lignite extract. The mass ratio of the lignite extract solids to the active compounds glyoxal and urea was 1:0.25:0.15. The liquid was heated to 90°C, and the reaction was stopped when the viscosity reached 400 mPa·s (approximately 63 min), yielding a dark-colored paper impregnation water-based resin.
[0039] S5. The base paper passes through the water-based resin at a speed of 500 m / s, absorbing the resin, and then the dry resin is removed by roller extrusion. By adjusting the concentration of the water-based resin and the pressure of the roller extrusion, the absorption of dry resin by the paper is maintained at 8 g / m². 2 After impregnation, the paper is dried in a 140°C drying zone, where the resin undergoes cross-linking and curing to obtain a photothermal dark-colored biodegradable paper film.
[0040] Example 3 The preparation steps for the photothermal type dark-colored biodegradable paper mulch film in this embodiment are as follows: S1. Grind the raw lignite and pass it through a 200-mesh sieve to obtain lignite powder. Add 10% potassium hydroxide to the lignite powder, add water with twice the mass of the lignite powder, heat to 80 ℃, and stir for alkali extraction for 30 min. Filter through a 300-mesh sieve to obtain solid lignite slag and liquid dark lignite extract.
[0041] S2. Commercial eucalyptus chemical wood pulp and lignite ash are mixed at a mass ratio of 10:3. Water is added to adjust the solids concentration to 10%, and the mixture is stirred evenly. 0.05% cationic polyacrylamide by weight of oven-dry pulp is added and stirred evenly to obtain dark wood pulp fibers filled with lignite ash.
[0042] S3. The added wood pulp is processed, pressed and dried according to the papermaking method of GB / T 24325-2009 standard to obtain dark-colored base paper with a basis weight of 60 grams.
[0043] S4. Formaldehyde and urea, two active compounds, were added to the lignite extract. The mass ratio of the lignite extract solids to the active compounds formaldehyde and urea was 1:0.30:0.10. The liquid was heated to 80°C and the reaction was stopped when the viscosity reached 330 mPa·s (approximately 56 min), yielding a dark-colored paper impregnation water-based resin.
[0044] S5. The base paper passes through the water-based resin at a speed of 400 m / s, absorbing the resin, and then the dry resin is removed by roller extrusion. By adjusting the concentration of the water-based resin and the pressure of the roller extrusion, the absorption of dry resin by the paper is maintained at 6 g / m². 2 After impregnation, the paper is dried in a 130°C drying zone, where the resin undergoes cross-linking and curing to obtain a photothermal dark-colored biodegradable paper film.
[0045] Example 4 The preparation steps for the photothermal type dark-colored biodegradable paper mulch film in this embodiment are as follows: S1. Grind the raw lignite and pass it through a 200-mesh sieve to obtain lignite powder. Add 10% potassium hydroxide to the lignite powder, add water with a mass of 3 times the weight of the lignite powder, heat to 100 ℃, and stir for alkali extraction for 60 min. Filter through a 300-mesh sieve to obtain solid lignite slag and liquid dark lignite extract.
[0046] S2. Mixed pulp (commercial pine chemical wood pulp and waste paper pulp in a 1:1 mass ratio) with lignite cinder in a 10:2 mass ratio, add water to adjust to a solids concentration of 10%, and stir until homogeneous. Add 0.1% cationic polyacrylamide by weight of oven-dry pulp, stir until homogeneous, and obtain dark wood pulp fibers filled with lignite cinder.
[0047] S3. The added wood pulp is processed, pressed and dried according to the papermaking method of GB / T 24325-2009 standard to obtain dark-colored base paper with a basis weight of 80 grams.
[0048] S4. Urea, formaldehyde, and polyethylene glycol (PEG) active compounds were added to the lignite extract. The mass ratio of lignite extract solids to urea, formaldehyde, and PEG was 1:0.15:0.25:0.30. The liquid was heated to 80°C, and the reaction was stopped when the viscosity reached 380 mPa·s (approximately 59 min), yielding a dark-colored water-based resin for paper impregnation.
[0049] S5. The base paper passes through the water-based resin at a speed of 400 m / s, absorbing the resin, and then the dry resin is removed by roller extrusion. By adjusting the concentration of the water-based resin and the pressure of the roller extrusion, the absorption of dry resin by the paper is maintained at 8 g / m². 2 After impregnation, the paper is dried in a 140°C drying zone, where the resin undergoes cross-linking and curing to obtain a photothermal dark-colored biodegradable paper film.
[0050] Comparative Example 1 The difference from Example 4 is that the resulting dark-colored base paper is not subjected to any resin impregnation treatment: S1. Grind the raw lignite and pass it through a 200-mesh sieve to obtain lignite powder. Add 10% potassium hydroxide to the lignite powder, add water with a mass of 3 times the weight of the lignite powder, heat to 100 ℃, and stir for alkali extraction for 60 min. Filter through a 300-mesh sieve to obtain solid lignite slag and liquid dark lignite extract.
[0051] S2. Mixed pulp (commercial pine chemical wood pulp and waste paper pulp in a 1:1 mass ratio) with lignite cinder in a 10:2 mass ratio, add water to adjust to a solids concentration of 10%, and stir until homogeneous. Add 0.1% cationic polyacrylamide by weight of oven-dry pulp, stir until homogeneous, and obtain dark wood pulp fibers filled with lignite cinder.
[0052] S3. The wood pulp with added filler is processed into paper using conventional papermaking methods to obtain dark-colored base paper with a basis weight of 80 grams, without any resin impregnation treatment.
[0053] Comparative Example 2 The difference from Example 4 is that only the base paper made from commercial pulp is impregnated with the water-based resin: S1. Grind the raw lignite and pass it through a 200-mesh sieve to obtain lignite powder. Add 10% potassium hydroxide (by weight of the lignite powder) and 3 times the weight of water to the lignite powder, heat to 100℃, and stir for 60 minutes for alkaline extraction. Filter through a 300-mesh sieve to obtain solid lignite slag and a liquid dark lignite extract.
[0054] S2. Commercial pine chemical pulp and waste paper pulp in a 1:1 mass ratio are processed, pressed and dried using conventional wet papermaking methods to obtain base paper with a basis weight of 80 grams.
[0055] S3. Urea, formaldehyde, and polyethylene glycol (PEG) active compounds were added to the lignite extract. The mass ratio of lignite extract solids to urea, formaldehyde, and PEG was 1:0.15:0.25:0.30. The liquid was heated to 80°C and the reaction was stopped when the viscosity reached 380 mPa·s (approximately 59 min), yielding a dark-colored water-based resin for paper impregnation.
[0056] S4. The base paper passes through the water-based resin at a speed of 400 m / s, absorbing the resin, and then the dry resin is removed by roller extrusion. By adjusting the concentration of the water-based resin and the pressure of the roller extrusion, the absorption of dry resin by the paper is maintained at 8 g / m². 2 After being impregnated, the paper is dried in a 130°C drying zone. During the drying process, the resin undergoes cross-linking and curing, becoming insoluble and infusible, resulting in a biodegradable paper film.
[0057] Test case The paper mulch films obtained in Examples 1-4, Comparative Examples 1 and 2 were used as test samples to compare photothermal performance and test degradation performance. The results are shown in Tables 1, 2 and 3.
[0058] Table 1. Performance changes of base paper before and after curing with water-based resin in Examples 1-4
[0059] Table 2 Comparison of photothermal performance of different paper mulch film products (maximum temperature of 28℃ and sunshine duration of 10 hours on the day).
[0060] Table 3 Degradation performance test of paper mulch film
[0061] It can be seen that the preparation methods in Examples 1-4 can all produce paper mulch films with durable photothermal properties, excellent mechanical strength, and controllable degradation. Comparative Example 1, without resin impregnation, resulted in paper mulch films with poor photothermal properties, poor heat retention, and uncontrollable degradation. Comparative Example 2, using only commercial pulp-based paper impregnated with aqueous resin, exhibited good heat retention but poor warming effect, generally low temperature, short functional period, and simple degradation behavior.
Claims
1. A photothermal type dark-colored biodegradable paper mulch film, characterized in that, Its preparation methods include: S1. Lignite powder, alkaline substances and appropriate amount of water are mixed, heated and stirred, and then separated into solid and liquid to obtain solid lignite slag and lignite extract; S2. Solid lignite slag is mixed with an appropriate amount of wood pulp, water, and retention and filtration aids, and stirred thoroughly to obtain dark wood pulp fibers filled with lignite slag; S3. Dark wood pulp fibers are processed using a wet papermaking process to obtain dark base paper; S4. Add an appropriate amount of polycondensation active compound to lignite extract, heat and stir to obtain an impregnation water-based resin, wherein the polycondensation active compound is an aldehyde compound, an amine compound and / or a polyol compound; S5. Dark-colored base paper is impregnated with water-based resin and then dried, allowing the resin to cross-link and cure during the paper drying process, resulting in a photothermal dark-colored biodegradable paper film.
2. The photothermal dark-colored biodegradable paper mulch film according to claim 1, characterized in that, In step S1, The alkaline substances are potassium hydroxide, sodium hydroxide, sodium carbonate, and / or ammonia. The amount of alkaline substance added is 8% to 12% of the mass of lignite powder; The amount of water added is 2 to 3 times the mass of lignite powder; The heating temperature is 70~100℃, and the heating and stirring time is 20~60 min.
3. The photothermal type dark-colored biodegradable paper mulch film according to claim 1, characterized in that: In step S2, Wood pulp and solid lignite slag are mixed, and water is added until the solids concentration reaches 8%-12%. After stirring evenly, a retention and filtration aid is added to the mixed slurry. The mass ratio of wood pulp to solid lignite slag is 10:2 to 10:3; The retention and filtration aid is an organic polymer flocculant, which can be at least one of cationic polymers, anionic polymers, amphoteric polymers, or nonionic polymers. The amount of retention and filtration aid is 0.01%-0.2% of the oven-dry pulp mass.
4. The photothermal type dark-colored biodegradable paper mulch film according to claim 1, characterized in that: Step S3 uses a wet papermaking process to obtain dark-colored base paper with a strength of 40~120 g / m².
5. The photothermal type dark-colored biodegradable paper mulch film according to claim 1, characterized in that: In step S4, Aldehydes are at least one of formaldehyde, acetaldehyde, propionaldehyde, glyoxal, glutaraldehyde, and furfural. The amine compound is at least one of urea, ethylenediamine, diethylenetriamine, triethylenetriamine, triethylenetetramine, hexamethylenediamine, aniline, and ethanolamine; The polyol compound is at least one of ethylene glycol, propylene glycol, glycerol, pentaerythritol, polyethylene glycol, and sorbitol.
6. The photothermal type dark-colored biodegradable paper mulch film according to claim 5, characterized in that: The mass ratio of solids to polycondensation-active compounds in lignite extract is 1:0.2 to 1:1.
0. Furthermore, the mass ratio of lignite extract solids to aldehydes, amines, and polyols is 1:(0~0.35):(0~0.25):(0~0.35), and the masses of aldehydes, amines, and polyols are not simultaneously zero.
7. The photothermal type dark-colored biodegradable paper mulch film according to claim 6, characterized in that: The mass ratio of solids in lignite extract to aldehydes, amines, and polyols is 1:(0.15~0.35):(0.10~0.25):(0.05~0.35).
8. The photothermal type dark-colored biodegradable paper mulch film according to claim 5, characterized in that, The heating temperature in step S4 is 60~90℃; The reaction ends when the rotational viscosity reaches 100~400 mPa·s.
9. The photothermal type dark-colored biodegradable paper mulch film according to claim 1, characterized in that, In step S5, The base paper passes through the impregnating water-based resin at a speed of 200~600 m / s. Based on the amount of dry resin in the impregnating water-based resin, the base paper absorbs 2~14 g / m of dry resin. 2 ; The drying temperature is 100~140℃.
10. The method for preparing the photothermal dark-colored biodegradable paper mulch film according to any one of claims 1-9.