Biodegradable mulching film and method for preparing the same

Abstract

The application relates to the technical field of high-molecular environmentally-friendly materials, in particular to a biodegradable mulching film and a preparation method thereof. The preparation method comprises the following steps: uniformly stirring and mixing polybutylene succinate, polyhydroxyalkanoate, modified mica sheet powder, tributyl citrate, salicylic acid and 2,4,6-trimethyl-2,4,6-triphenylcyclotrisiloxane, melting and plasticizing the mixture in a screw extruder, extruding through a ring-shaped die, filling dry air into the center of the die, and simultaneously stretching the extruded high-temperature melt in the transverse and longitudinal directions through the cooperation of the cooling air ring installed at the die part, finally leading out through the traction device on the upper part of the rack, and then leading into the winding device to wind the finished product. The biodegradable mulching film has excellent barrier properties, good soil heat preservation effect and water evaporation prevention effect in the soil.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high-molecular environmentally friendly materials, and particularly relates to a biodegradable mulch film and a preparation method thereof. BACKGROUND

[0002] In the field of agriculture, the application of biodegradable mulch film is increasingly widespread. Because traditional plastic mulch is often difficult to degrade after use, causing serious soil pollution, while biodegradable mulch can effectively solve this problem. Biodegradable mulch is a kind of farmland covering film made of biodegradable materials. This kind of mulch can gradually decompose under the action of soil microorganisms, and finally transform into harmless substances such as water, carbon dioxide and biomass. According to its degradation mechanism, biodegradable mulch is mainly divided into two categories: complete biodegradation and additive biodegradation. Complete biodegradable mulch is made of completely decomposable materials, such as polylactic acid or polyhydroxyalkanoate. While additive biodegradable mulch is made by adding biodegradable agents to traditional plastics to accelerate the decomposition process. In addition, according to the different raw materials, biodegradable mulch can also be subdivided into starch-based, cellulose-based, etc. These classifications are mainly based on the manufacturing raw materials of the mulch. At present, many countries around the world are actively promoting the use of biodegradable mulch, especially in organic agriculture and green agriculture. Farmers and agricultural enterprises are increasingly aware of the environmental advantages of biodegradable mulch, and are replacing traditional mulch. At the same time, the government also encourages its use through policies such as subsidies and tax incentives. With the continuous progress of biodegradable material technology and the reduction of costs, it is expected that biodegradable mulch will play a greater role in agricultural production in the future.

[0003] Chinese patent publication No. CN107325502 discloses a water-retaining and fertilizer-increasing biodegradable agricultural mulch film and a preparation method thereof, comprising: heating the ground low-rank coal and KOH solution to 40-90℃, filtering the filtrate after reaction, cooling, adjusting the pH value to be acidic, and standing until no fixed substances are precipitated, then performing vacuum filtration on the filter cake, and drying to obtain low-rank coal-based humic acid; reacting the low-rank coal-based humic acid with a hydrophilic monomer, an initiator and a crosslinking agent to prepare a low-rank coal-based humic acid superabsorbent resin; taking biodegradable materials and low-rank coal-based humic acid superabsorbent resin, granulating and blowing film to prepare the water-retaining and fertilizer-increasing biodegradable agricultural mulch film.

[0004] Chinese patent publication No. CN113999502 discloses an anti-UV aging biodegradable mulch film and a preparation method thereof, comprising the following steps: mixing two-dimensional layered materials and ultraviolet absorbers into dichloromethane solution, and then performing probe ultrasonic treatment, and then adding biodegradable resin for continuous stirring; centrifuging and drying the obtained product to obtain anti-UV aging components; uniformly mixing the prepared anti-aging components, biodegradable resin and other additives, and then blow molding at 160-180℃ to obtain the anti-UV aging biodegradable mulch film.

[0005] Although the mulch film has the biodegradation function, the barrier property of the mulch film is general, and the mulch film cannot play a good heat preservation effect on the soil and prevent evaporation of water in the soil. SUMMARY

[0006] In order to overcome the above problems of the prior art, the present application provides a biodegradable mulch film and a preparation method thereof. The biodegradable mulch film has excellent barrier properties, and has a good heat preservation effect on the soil and an effect of preventing evaporation of water in the soil.

[0007] In order to achieve the above-mentioned purposes of the application, the following technical solutions are adopted in the present application:

[0008] A biodegradable mulch film comprises the following components by weight:

[0009] 50-60 parts of polybutylene succinate, 20-30 parts of polyhydroxyalkanoate, 10-15 parts of modified mica flake powder, 1-3 parts of tributyl citrate, 1-3 parts of salicylic acid, and 0.5-1 part of 2,4,6-trimethyl-2,4,6-triphenyltrisiloxane.

[0010] In the technical solution of the present application, polybutylene succinate and polyhydroxyalkanoate are used as biodegradable resins, tributyl citrate is used as a plasticizer, salicylic acid is used as a light stabilizer, and 2,4,6-trimethyl-2,4,6-triphenyltrisiloxane is used as an ultraviolet absorber. In order to improve the barrier property of the mulch film, the present application adds mica flake powder to the mulch film. The mica flake powder has a layered structure, and when it is dispersed in a plastic matrix, it forms a natural barrier, thereby improving the gas barrier property. In addition, when the resin component in the mulch film degrades, the mica flake powder can be dispersed in the soil. The mica flake powder contains various nutrients required for plant growth, such as potassium, magnesium, and silicon. These elements can be slowly released and absorbed by plants. At the same time, the mica flake powder has the ability to adsorb harmful substances in the soil, such as heavy metals and organic pollutants, which helps to reduce the negative impact of these substances on plants and the environment.

[0011] As a preferred embodiment, the preparation method of the modified mica flake powder comprises the following steps:

[0012] S1. Sodium silicate and sodium dodecylbenzenesulfonate are added to deionized water and stirred to dissolve, to obtain a mixed solution. Mica flake powder is added to the mixed solution and stirred uniformly to obtain a suspension;

[0013] S2. Under the condition of stirring the suspension, hydrochloric acid is added dropwise to the suspension to adjust the pH to 5, and heated to 50℃ and kept for 3h. After filtration, washing and drying, a composite particle intermediate is obtained;

[0014] S3, the composite particle intermediate is placed in a muffle furnace for calcination, and cooled to obtain a silica-mica flake powder composite particle;

[0015] S4, the epoxy propyl dodecyl diethyl ammonium chloride is added to deionized water and stirred to dissolve to prepare an epoxy propyl dodecyl diethyl ammonium chloride solution, then polyethylene imine is added to the epoxy propyl dodecyl diethyl ammonium chloride solution, heated to 80°C, and incubated for reaction, followed by vacuum distillation and vacuum drying to obtain polyethylene imine modified epoxy propyl dodecyl diethyl ammonium chloride;

[0016] S5, the silica-mica flake powder composite particle is added to deionized water and stirred to disperse uniformly to obtain a suspension; the polyethylene imine modified epoxy propyl dodecyl diethyl ammonium chloride is added to the suspension, heated and stirred for reaction, followed by centrifugal separation, washing, and drying to obtain a modified mica flake powder.

[0017] In the technical scheme of the present application, as described above, the barrier property of the mulch film is improved by doping mica flake powder in the film, but since the mica flake powder has a sheet structure and the distance between layers is small, it is prone to agglomeration in the resin during the preparation of the mulch film, which affects the improvement of the barrier property of the mulch film by the mica flake powder. Therefore, the mica flake powder is modified in the present application, and the epoxy propyl dodecyl diethyl ammonium chloride is modified by polyethylene imine to prepare polyethylene imine modified epoxy propyl dodecyl diethyl ammonium chloride. The epoxy propyl dodecyl diethyl ammonium chloride has the ability to insert between the layers of the mica flake powder, and the polyethylene imine is inserted between the layers of the mica flake powder. Since the polyethylene imine has a hyperbranched molecular structure and has a large steric hindrance, it can significantly increase the distance between the layers of the mica flake powder, thereby improving the dispersion of the mica flake powder in the resin and further improving the barrier property of the mulch film.

[0018] As described above, the barrier property of the mulch film is improved by doping mica flake powder in the film and improving its dispersion in the resin. However, there is a further problem that the mechanical strength of the mulch film is reduced after the mica flake powder is doped in the resin, and the mulch film is prone to cracking during the stretching step in the preparation process. Therefore, the mica flake powder is further modified in the present application, and nano-silica is prepared on the surface of the mica flake powder particles using sodium silicate as the raw material and the mica flake powder as the matrix. The nano-silica can increase the roughness of the surface of the mica flake powder and improve the bonding force between the mica flake powder and the resin, thereby improving the mechanical strength of the mulch film and avoiding cracking of the mulch film during the preparation process.

[0019] Preferably, in step S1, the mass ratio of mica flake powder to sodium silicate is 1:2-3.7.

[0020] The application is to make the surface of mica sheet powder combined with sufficient nano-silicon dioxide, improve the mechanical strength of mulch, and control the mass ratio of mica sheet powder to sodium silicate to be less than 1:2. However, with the increase of the amount of sodium silicate, the application team accidentally found that when the mass ratio of mica sheet powder to sodium silicate is less than 1:3.7, the barrier property of the mulch decreases significantly, which may be because after the surface of the mica sheet powder is combined with a large amount of nano-silicon dioxide, the mica sheet powder has a larger surface area, and more gap structures are formed between the mica sheet powder and the resin, thereby causing the barrier property of the mulch to decrease. Therefore, the application simultaneously controls the mass ratio of mica sheet powder to sodium silicate to be greater than 1:3.7.

[0021] As described above, the application improves the bonding force between the mica sheet powder and the resin by preparing nano-silicon dioxide on the surface of the mica sheet powder particles, thereby improving the mechanical strength of the mulch.

[0022] Preferably, in step S3, the calcination temperature is 450-480℃.

[0023] Preferably, in step S4, the mass ratio of epoxy propyl dodecyl diethyl ammonium chloride to polyethyleneimine is 1:0.3-0.8.

[0024] Preferably, in step S5, the mass ratio of silicon dioxide-mica sheet powder composite particles to polyethyleneimine modified epoxy propyl dodecyl diethyl ammonium chloride is 1:2-5.

[0025] Preferably, in step S5, the reaction temperature is 50-60℃.

[0026] A preparation method of a biodegradable mulch, comprising the following steps:

[0027] After the polybutylene succinate, polyhydroxyalkanoate, modified mica sheet powder, tributyl citrate, salicylic acid and 2,4,6-trimethyl-2,4,6-triphenylcyclotrisiloxane are stirred and uniformly mixed, they are added into a screw extruder for melt plasticization, extruded through an annular die, dry air is filled into the center of the die, and the extruded high-temperature melt is stretched in the transverse and longitudinal directions at the same time through the combined action of the cooling air ring installed at the die part, finally drawn out through the traction device on the upper part of the rack, and then introduced into the winding device to be wound into finished products.

[0028] The application has the following beneficial effects:

[0029] 1) By doping mica sheet powder in the mulch, the mica powder has a layered structure, and when it is dispersed in the plastic matrix, a natural barrier is formed, thereby improving the gas barrier property and having a good heat preservation effect on the soil and preventing the evaporation of water in the soil;

[0030] 2) The polyethyleneimine modified epoxy propyl dodecyl diethyl ammonium chloride is prepared by modifying the epoxy propyl dodecyl diethyl ammonium chloride with polyethyleneimine. The polyethyleneimine is inserted into the interlayer of the mica flake powder due to the intercalation ability of the epoxy propyl dodecyl diethyl ammonium chloride. The polyethyleneimine has a hyperbranched molecular structure and a large steric hindrance, which can significantly increase the distance between the layers of the mica flake powder, thereby improving the dispersion performance of the mica flake powder in the resin and further improving the barrier performance of the mulch film.

[0031] 3) The nanosilica is prepared on the surface of the mica flake powder with sodium silicate as the raw material and the mica flake powder as the matrix. The nanosilica can improve the roughness of the surface of the mica flake powder and improve the bonding force between the mica flake powder and the resin, thereby improving the mechanical strength of the mulch film and avoiding the cracking of the mulch film during the preparation process due to stretching. DETAILED DESCRIPTION

[0032] The present application will be further described in detail with reference to the following specific examples. Those skilled in the art will be able to implement the present application based on these descriptions. In addition, the examples of the present application involved in the following descriptions are generally only a part of the examples of the present application, but not all the examples. Therefore, all other examples obtained by those skilled in the art based on the examples in the present application without making creative efforts should belong to the scope of protection of the present application.

[0033] Unless otherwise specified, the raw materials used in the examples of the present application are commercially available or can be obtained by those skilled in the art. Unless otherwise specified, the methods used in the examples of the present application are the methods mastered by those skilled in the art.

[0034] Example 1

[0035] A biodegradable mulch film, comprising the following components by weight:

[0036]

[0037] The preparation method of the modified mica flake powder comprises the following steps:

[0038] S1, 10.0 g of sodium silicate and 0.05 g of sodium dodecylbenzenesulfonate are added to 500 mL of deionized water and stirred to dissolve to obtain a mixed solution. The mica flake powder is added to the mixed solution, and the mass ratio of the mica flake powder to the sodium silicate is 1:3.5. The mixture is stirred uniformly to obtain a suspension;

[0039] S2, under the condition of stirring the suspension, 5.0% hydrochloric acid is added dropwise to the suspension to adjust the pH to 5, and heated to 50℃ for 3h. After filtration, washing and drying, a composite particle intermediate is obtained.

[0040] S3, placing the composite particle intermediate in a muffle furnace and calcining at 460°C for 5h, cooling, to obtain a silica-mica flake powder composite particle;

[0041] S4, adding 3.0g of epoxypropyl dodecyl diethyl ammonium chloride to 300mL of deionized water, stirring to dissolve to prepare an epoxypropyl dodecyl diethyl ammonium chloride solution, then adding polyethyleneimine to the epoxypropyl dodecyl diethyl ammonium chloride solution, the mass ratio of epoxypropyl dodecyl diethyl ammonium chloride to polyethyleneimine being 1:0.7, heating to 80°C, incubating for 3h, and then performing vacuum distillation and vacuum drying to obtain polyethyleneimine-modified epoxypropyl dodecyl diethyl ammonium chloride;

[0042] S5, adding 2.0g of the silica-mica flake powder composite particle to 300mL of deionized water, stirring to disperse uniformly to obtain a suspension; adding polyethyleneimine-modified epoxypropyl dodecyl diethyl ammonium chloride to the suspension, the mass ratio of silica-mica flake powder composite particle to polyethyleneimine-modified epoxypropyl dodecyl diethyl ammonium chloride being 1:4, heating to 55°C, stirring to react for 5h, and then performing centrifugal separation, washing, and drying to obtain the modified mica flake powder.

[0043] A method for preparing a biodegradable mulch film, comprising the following steps:

[0044] After the polybutylene succinate, polyhydroxyalkanoate, modified mica flake powder, tributyl citrate, salicylic acid, and 2,4,6-trimethyl-2,4,6-triphenyltrisiloxane are stirred and mixed uniformly, they are added to a screw extruder and melt plasticized at 200°C, extruded through an annular die, dry air is fed from the center of the die, and the extruded high-temperature melt is simultaneously stretched in the transverse and longitudinal directions by the combined action of the cooling air ring installed at the die site, stretched 2 times in the transverse direction, and then stretched 1.5 times in the longitudinal direction, finally drawn out by the traction device on the upper part of the machine frame, and then introduced into the winding device to wind into a finished product.

[0045] Example 2

[0046] A biodegradable mulch film, comprising the following components by weight:

[0047]

[0048] A method for preparing a modified mica flake powder, comprising the following steps:

[0049] S1, adding 10.0g of sodium silicate and 0.05g of sodium dodecyl benzene sulfonate to 500mL of deionized water, stirring to dissolve, to obtain a mixed solution, adding mica flake powder to the mixed solution, the mass ratio of mica flake powder to sodium silicate being 1:2.5, stirring to obtain a suspension;

[0050] S2, under the condition of stirring the suspension, 5.0% hydrochloric acid was added dropwise to the suspension to adjust the pH to 5, heated to 50°C, and incubated for 3h, then separated, washed, and dried by filtration to obtain a composite particle intermediate;

[0051] S3, the composite particle intermediate was calcined in a muffle furnace at 460°C for 5h, and then cooled to obtain a silicon dioxide-mica flake powder composite particle;

[0052] S4, 3.0g of epoxypropyl dodecyl diethyl ammonium chloride was added to 300mL of deionized water and stirred to dissolve to prepare an epoxypropyl dodecyl diethyl ammonium chloride solution, then polyethyleneimine was added to the epoxypropyl dodecyl diethyl ammonium chloride solution, the mass ratio of epoxypropyl dodecyl diethyl ammonium chloride to polyethyleneimine was 1:0.4, heated to 80°C, and incubated for 3h, then vacuum distilled and vacuum dried to obtain polyethyleneimine modified epoxypropyl dodecyl diethyl ammonium chloride;

[0053] S5, 2.0g of the silicon dioxide-mica flake powder composite particle was added to 300mL of deionized water and stirred to disperse uniformly to obtain a suspension; polyethyleneimine modified epoxypropyl dodecyl diethyl ammonium chloride was added to the suspension, the mass ratio of the silicon dioxide-mica flake powder composite particle to the polyethyleneimine modified epoxypropyl dodecyl diethyl ammonium chloride was 1:3, heated to 55°C, and stirred for 5h, then centrifuged, washed, and dried to obtain a modified mica flake powder.

[0054] A method for preparing a biodegradable mulch film, comprising the following steps:

[0055] After the polybutylene succinate, polyhydroxyalkanoate, modified mica flake powder, tributyl citrate, salicylic acid, and 2,4,6-trimethyl-2,4,6-triphenyltrisiloxane were stirred and mixed uniformly, they were added to a screw extruder and melted and plasticized at 200°C, extruded through an annular die, dry air was injected from the center of the die, and the extruded high-temperature melt was simultaneously stretched in the transverse and longitudinal directions by the combined action of the cooling air ring installed at the die site, stretched 2 times in the transverse direction, and then stretched 1.5 times in the longitudinal direction, finally drawn out through the traction device on the upper part of the machine frame, and then introduced into the winding device to form the finished product.

[0056] Example 3

[0057] A biodegradable mulch film, comprising the following components by weight:

[0058]

[0059] A method for preparing a modified mica flake powder, comprising the following steps:

[0060] S1, 10.0 g of sodium silicate and 0.05 g of sodium dodecyl benzene sulfonate were added into 500 mL of deionized water and stirred to dissolve to obtain a mixed solution, mica sheet powder was added into the mixed solution, the mass ratio of the mica sheet powder to the sodium silicate was 1:3, and stirring was performed uniformly to obtain a suspension;

[0061] S2, under the condition that the suspension was stirred, 5.0% hydrochloric acid was added dropwise into the suspension to adjust the pH to 5, heating was performed to 50 DEG C, and reaction was performed for 3 h, and after filtration separation, washing, and drying, a composite particle intermediate was obtained;

[0062] S3, the composite particle intermediate was calcined in a muffle furnace at 460 DEG C for 5 h, and after cooling, a silicon dioxide-mica sheet powder composite particle was obtained;

[0063] S4, 3.0 g of epoxy propyl dodecyl diethyl ammonium chloride was added into 300 mL of deionized water and stirred to dissolve to prepare an epoxy propyl dodecyl diethyl ammonium chloride solution, then polyethylene imine was added into the epoxy propyl dodecyl diethyl ammonium chloride solution, the mass ratio of the epoxy propyl dodecyl diethyl ammonium chloride to the polyethylene imine was 1:0.6, heating was performed to 80 DEG C, and reaction was performed for 3 h, and after vacuum distillation and vacuum drying, a polyethylene imine modified epoxy propyl dodecyl diethyl ammonium chloride was obtained;

[0064] S5, 2.0 g of the silicon dioxide-mica sheet powder composite particle was added into 300 mL of deionized water and stirred to disperse uniformly to obtain a suspension, the polyethylene imine modified epoxy propyl dodecyl diethyl ammonium chloride was added into the suspension, the mass ratio of the silicon dioxide-mica sheet powder composite particle to the polyethylene imine modified epoxy propyl dodecyl diethyl ammonium chloride was 1:3, heating was performed to 55 DEG C, and reaction was performed for 5 h, and after centrifugal separation, washing, and drying, a modified mica sheet powder was obtained.

[0065] The preparation method of the biodegradable mulching film comprises the following steps:

[0066] After the polybutylene succinate, the polyhydroxyalkanoate, the modified mica sheet powder, the tributyl citrate, the salicylic acid, and the 2,4,6-trimethyl-2,4,6-triphenyltrisiloxane were stirred and mixed uniformly, they were added into a screw extruder and melt plasticized at 200 DEG C, were extruded through an annular die, dry air was filled into the center of the die, and the extruded high-temperature melt was simultaneously stretched in the transverse and longitudinal directions by the combined action of the cooling air ring installed at the die part, was then stretched by 2 times in the transverse direction and by 1.5 times in the longitudinal direction, and finally was drawn out through the traction device on the upper part of the machine frame and then was introduced into the winding device to be wound into a finished product.

[0067] Example 4

[0068] A biodegradable mulching film comprises the following components in parts by weight:

[0069]

[0070] The preparation method of the modified mica sheet powder comprises the following steps:

[0071] S1, 10.0 g of sodium silicate and 0.05 g of sodium dodecyl benzene sulfonate are added to 500 mL of deionized water and stirred to dissolve, to obtain a mixed solution, mica sheet powder is added to the mixed solution, the mass ratio of mica sheet powder to sodium silicate is 1:3.7, and stirring is uniform, to obtain a suspension;

[0072] S2, under the condition of stirring the suspension, 5.0% hydrochloric acid is added dropwise to the suspension to adjust the pH to 5, heated to 50℃, and incubated for 3h, and after filtration separation, washing and drying, a composite particle intermediate is obtained;

[0073] S3, the composite particle intermediate is placed in a muffle furnace and calcined at 480℃ for 5h, and cooled to obtain a silica-mica sheet powder composite particle;

[0074] S4, 3.0 g of epoxy propyl dodecyl diethyl ammonium chloride is added to 300 mL of deionized water and stirred to dissolve to prepare an epoxy propyl dodecyl diethyl ammonium chloride solution, then polyethyleneimine is added to the epoxy propyl dodecyl diethyl ammonium chloride solution, the mass ratio of epoxy propyl dodecyl diethyl ammonium chloride to polyethyleneimine is 1:0.8, heated to 80℃, and incubated for 3h, and after vacuum distillation and vacuum drying, a polyethyleneimine modified epoxy propyl dodecyl diethyl ammonium chloride is obtained;

[0075] S5, 2.0 g of silica-mica sheet powder composite particles are added to 300 mL of deionized water and stirred to disperse uniformly to obtain a suspension; polyethyleneimine modified epoxy propyl dodecyl diethyl ammonium chloride is added to the suspension, the mass ratio of silica-mica sheet powder composite particles to polyethyleneimine modified epoxy propyl dodecyl diethyl ammonium chloride is 1:5, heated to 60℃, and stirred for 5h, and after centrifugal separation, washing and drying, a modified mica sheet powder is obtained.

[0076] The preparation method of the biodegradable mulch film comprises the following steps:

[0077] Polybutylene succinate, polyhydroxyalkanoate, modified mica flake powder, tributyl citrate, salicylic acid and 2,4,6-trimethyl-2,4,6-triphenylcyclotrisiloxane are stirred and mixed uniformly, then added into a screw extruder for melt plasticization at 200℃, extruded through an annular die, dry air is filled into the center of the die, and the extruded high-temperature melt is stretched in the transverse and longitudinal directions simultaneously by the combined action of the cooling air ring installed at the die site, stretched 2 times in the transverse direction, then stretched 1.5 times in the longitudinal direction, finally drawn out through the traction device on the upper part of the machine frame, and then introduced into the winding device to form the finished product.

[0078] Example 5

[0079] A biodegradable mulch film, comprising the following components by weight parts:

[0080]

[0081]

[0082] The preparation method of the modified mica flake powder comprises the following steps:

[0083] S1, 10.0g of sodium silicate and 0.05g of sodium dodecyl benzene sulfonate are added to 500mL of deionized water and stirred to dissolve, obtaining a mixed solution, mica flake powder is added to the mixed solution, the mass ratio of mica flake powder to sodium silicate is 1:2, and stirring is uniform, obtaining a suspension;

[0084] S2, under the condition of stirring the suspension, 5.0% hydrochloric acid is added dropwise to the suspension to adjust the pH to 5, heated to 50℃, and kept for 3h, then separated, washed and dried by filtration to obtain a composite particle intermediate;

[0085] S3, the composite particle intermediate is calcined in a muffle furnace at 450℃ for 5h, and cooled to obtain a silica-mica flake powder composite particle;

[0086] S4, 3.0g of epoxypropyl dodecyl diethyl ammonium chloride is added to 300mL of deionized water and stirred to dissolve to prepare an epoxypropyl dodecyl diethyl ammonium chloride solution, then polyethyleneimine is added to the epoxypropyl dodecyl diethyl ammonium chloride solution, the mass ratio of epoxypropyl dodecyl diethyl ammonium chloride to polyethyleneimine is 1:0.3, heated to 80℃, and kept for 3h, then distilled under reduced pressure and vacuum dried to obtain polyethyleneimine modified epoxypropyl dodecyl diethyl ammonium chloride;

[0087] S5, 2.0 g of the silica-mica flake powder composite particles were added to 300 mL of deionized water, and stirred to disperse uniformly to obtain a suspension; polyethyleneimine modified epoxy propyl dodecyl diethyl ammonium chloride was added to the suspension, the mass ratio of the silica-mica flake powder composite particles to the polyethyleneimine modified epoxy propyl dodecyl diethyl ammonium chloride was 1:2, heated to 50 DEG C, and stirred to react for 5 h, and then centrifuged, washed, and dried to obtain the modified mica flake powder.

[0088] The preparation method of the biodegradable mulch film comprises the following steps:

[0089] The polybutylene succinate, polyhydroxyalkanoate, modified mica flake powder, tributyl citrate, salicylic acid, and 2,4,6-trimethyl-2,4,6-triphenyltrisiloxane were stirred and mixed uniformly, and then added into a screw extruder for melt plasticization at 200 DEG C, extruded through an annular die, dry air was filled into the center of the die, and the extruded high-temperature melt was simultaneously stretched in the transverse and longitudinal directions by the combined action of the cooling air ring installed at the die part, stretched 2 times in the transverse direction, and then stretched 1.5 times in the longitudinal direction, and finally drawn out through the traction device on the upper part of the machine frame, and then introduced into the winding device to be wound into a finished product.

[0090] Comparative Example 1

[0091] The difference between Comparative Example 1 and Example 1 is that:

[0092] The modified mica flake powder is not contained in the mulch film components;

[0093] The remaining operation steps are the same as those in Example 1.

[0094] Comparative Example 2

[0095] The difference between Comparative Example 2 and Example 1 is that:

[0096] The modified mica flake powder in the mulch film components is replaced by ordinary mica flake powder.

[0097] The remaining operation steps are the same as those in Example 1.

[0098] Comparative Example 3

[0099] The difference between Comparative Example 3 and Example 1 is that:

[0100] The steps S1, S2, and S3 in the preparation method of the modified mica powder are omitted,

[0101] That is, the nano-silicon dioxide is not combined on the surface of the mica flake powder,

[0102] The remaining operation steps are the same as those in Example 1.

[0103] Comparative Example 4

[0104] Comparative Example 4 differs from Example 4 in that:

[0105] The mass ratio of mica flake powder to sodium silicate was 1:3.8.

[0106] The remaining operation steps were the same as Example 1.

[0107] Performance test

[0108] 1, mulch barrier performance test:

[0109] The barrier performance of the mulch was characterized by water vapor transmission rate. According to the test standard GB / T1037-2021 "Plastic film and sheet water vapor transmission performance determination cup type weight gain and weight loss method", the water vapor transmission amount of the mulch in 24h was tested, and the test temperature was controlled at 38℃, and the relative humidity was controlled at 90%.

[0110]

[0111] 2, mechanical property test of mulch

[0112] 2.1, whether the mulch was damaged during preparation was determined by observing whether there were fine cracks on the surface of the mulch with the naked eye;

[0113] 2.2, the mechanical strength of the mulch was tested by using a Q800 type dynamic mechanical analyzer. The mulch was cut into a long strip with a size of 30x10mm, and was placed in a tensile clamp, one end was fixed, and the other end could move with the clamp. The pre-load was 0.01N to prevent the mulch from bending during the test. The temperature was kept at 20℃, the frequency was set to 1Hz, and the stress was gradually increased from 0 at a speed of 5MPa / s. The strain change of the mulch was recorded until the mulch was broken.

[0114] The stress at the breaking point was taken as the tensile strength of the mulch, and the test was repeated three times, and the average value was taken as the result.

[0115]

[0116] 3, thermal stability test:

[0117] A Q10 type differential scanning calorimeter was used for temperature scanning test to determine the glass transition temperature and melting temperature of the mulch. After crushing the mulch, 3.5mg was placed in an aluminum crucible, sealed and compacted. The empty crucible was used as a blank control. The sample crucible and empty crucible were placed in the instrument, and the temperature was heated from 20℃ to 300℃ at a speed of 10℃ / min. The average temperature of the stepwise descending region in the thermogram was taken as the glass transition temperature, and the valley temperature was taken as the melting temperature. The test was repeated three times, and the average value was taken as the result. The average value and standard deviation were used, and the significance was analyzed by Duncan method.

[0118]

[0119]

[0120] The above merely preferred embodiments of the present application, it should be noted that the preferred embodiments described above should not be considered as a limitation of the present application, the scope of protection of the present application should be limited to the scope defined by the claims. For those of ordinary skill in the art, without departing from the spirit and scope of the present application, can also make a number of improvements and refinements, these improvements and refinements should also be considered as the scope of protection of the present application.

Claims

1. A biodegradable mulch film, characterized by, Comprise the following components by weight parts: Polybutylene succinate 50-60 parts, Polyhydroxyaliphatic ester 20-30 parts, Modified mica flake powder 10-15 parts, Tributyl citrate 1-3 parts, Salicylic acid 1-3 parts, 2,4,6-trimethyl-2,4,6-triphenyltrisiloxane 0.5-1 parts; The preparation method of the modified mica flake powder comprises the following steps: S1, sodium silicate and sodium dodecyl benzene sulfonate are added to deionized water and stirred to dissolve, obtaining a mixed solution, mica flake powder is added to the mixed solution and stirred uniformly, obtaining a suspension; the mass ratio of mica flake powder to sodium silicate is 1:2-3.7; S2, under the condition of stirring the suspension, hydrochloric acid is added dropwise to the suspension to adjust the pH to 5, heated to 50℃, and kept for 3h, after filtration separation, washing and drying, a composite particle intermediate is obtained; S3, the composite particle intermediate is calcined in a muffle furnace, and cooled to obtain a silica-mica flake powder composite particle; S4, epoxy propyl dodecyl diethyl ammonium chloride is added to deionized water and stirred to dissolve to prepare an epoxy propyl dodecyl diethyl ammonium chloride solution, then polyethyleneimine is added to the epoxy propyl dodecyl diethyl ammonium chloride solution, heated to 80℃, and kept for reaction, after vacuum distillation and vacuum drying, polyethyleneimine modified epoxy propyl dodecyl diethyl ammonium chloride is obtained; the mass ratio of epoxy propyl dodecyl diethyl ammonium chloride to polyethyleneimine is 1:0.3-0.8; S5, the silica-mica flake powder composite particle is added to deionized water and stirred to disperse uniformly, obtaining a suspension; polyethyleneimine modified epoxy propyl dodecyl diethyl ammonium chloride is added to the suspension, heated and stirred to react, after centrifugal separation, washing and drying, a modified mica flake powder is obtained; the mass ratio of silica-mica flake powder composite particle to polyethyleneimine modified epoxy propyl dodecyl diethyl ammonium chloride is 1:2-5.

2. The biodegradable mulch film according to claim 1, characterized by In the step S3, the calcination temperature is 450-480℃.

3. The biodegradable mulching film according to claim 1, wherein In the step S5, the reaction temperature is 50-60℃.

4. A process for the production of biodegradable mulching film as claimed in any one of claims 1 to 3, wherein, Comprise the following steps: After the polybutylene succinate, polyhydroxyaliphatic ester, modified mica flake powder, tributyl citrate, salicylic acid and 2,4,6-trimethyl-2,4,6-triphenyltrisiloxane are stirred and mixed uniformly, they are introduced into a screw extruder for melt plasticization, then introduced into a die, cooled by a cooling roller to form a thick sheet, the thick sheet is first stretched in the transverse direction, and then stretched in the longitudinal direction, obtaining a biodegradable mulch film.

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