Black and white light conversion weed control mulching film and preparation method thereof

Abstract

The application discloses a black-and-white light-conversion weed-inhibiting mulching film and a preparation method thereof, and belongs to the field of agricultural polymer films. The preparation method comprises the following steps: S1, reflux reaction, spray drying are carried out on titanium dioxide, nano zinc oxide, diethanolamine and isopropyl alcohol to obtain a modified filler; S2, low-density polyethylene powder, zinc stearate, antioxidant 1010, a composite light-conversion agent, the modified filler, a plasticizer and polyethylene wax are uniformly mixed, and then are subjected to banburying and granulation to obtain a white light-conversion functional master batch; S3, tetramethylpiperidinol and itaconic acid are added into a reactor for decompression reaction; the reaction product, metallocene linear low-density polyethylene powder and a light stabilizer are subjected to melt blending and granulation to obtain an anti-aging modified master batch; and S4, raw materials of a light-reflecting layer, a reinforcing layer and a black layer are subjected to melt co-extrusion to obtain a finished product mulching film. The black-and-white light-conversion weed-inhibiting mulching film prepared by the application has strong anti-aging capacity, high mechanical performance, good light-conversion effect and good weed-inhibiting effect.

Description

TECHNICAL FIELD

[0001] The application discloses a black-and-white light conversion weed-inhibiting mulching film and a preparation method thereof, and belongs to the field of agricultural polymer films. BACKGROUND

[0002] As a core technology support for modern agriculture to achieve yield increase and efficiency improvement, the functional design of agricultural mulching film and the adaptability to crop growth period demand and regional climate conditions directly determine the comprehensive benefits of agricultural production. The current market mainstream agricultural mulching film mainly includes transparent film, black film, white film, green film and other single-function products, but their respective performance limitations have gradually become a bottleneck restricting the high-quality development of modern agriculture.

[0003] Among them, black mulching film is widely used in weed control due to its light-shielding and weed-inhibiting characteristics, but the existing products mostly use LDPE single resin system, and the carbon black particles are prone to agglomeration, which not only leads to a significant decrease in the mechanical strength of the film material, but also makes the film material prone to damage in agricultural operations and strong wind and other field environments, and accelerates the aging and degradation of the film material, shortening the service life. At the same time, its light-shielding characteristics also affect the light demand of crops at the seedling stage to some extent, which is not conducive to the growth of seedlings. The core advantage of white mulching film is light-reflecting and temperature-increasing and water-retaining and moisture-retaining, but due to its poor light-shielding performance, most natural light can penetrate the film material, which cannot effectively block the photosynthesis of weeds, leading to the problem of weed proliferation. In actual application, herbicides need to be used to make up for the shortcomings of weed inhibition, which not only increases the cost of agricultural materials and labor, but also easily causes soil pesticide residues and destroys the soil ecological environment, which is contrary to the development needs of modern agriculture simplification and greenization. In addition, the single function of the existing single-color mulching film is in sharp contradiction with the dynamic needs of the whole growth period of crops. After entering the fruit enlargement period, it is necessary to rely on the light-reflecting function to improve the uniformity of fruit color, and it is also necessary to ensure the water-retaining and drought-preventing and long-lasting properties of the film material. This "single function cannot meet the needs of multiple stages" situation leads farmers to frequently change the mulching film according to the growth stage of crops, which not only increases the production input, but also consumes a lot of manpower and material resources, and cannot meet the actual needs of large-scale and intensive agricultural production.

[0004] In summary, due to the problems of single function, poor environmental adaptability and insufficient durability, the existing single-color mulching film cannot meet the complex needs of weed inhibition, temperature increase, water retention, quality improvement and long-term use in modern agriculture, and it is urgent to develop new mulching film products with multiple functions to improve the efficiency of agricultural production. SUMMARY

[0005] In order to solve the above problems in the prior art, the application provides a black-and-white light conversion weed-inhibiting mulching film and a preparation method thereof, and achieves the following application purposes: a black-and-white light conversion weed-inhibiting mulching film with good mechanical properties and strong weather resistance is prepared.

[0006] To achieve the above object, the technical scheme adopted is as follows:

[0007] A black-and-white light conversion weed control mulch film has a three-layer structure of a reflective layer, a reinforcing layer and a black layer.

[0008] The reflective layer is prepared from the following raw materials in parts by weight: 14-18 parts of white light conversion functional masterbatch, 10-15 parts of anti-aging modified masterbatch, 50-60 parts of linear low-density polyethylene particles, 25-33 parts of metallocene linear low-density polyethylene particles and 6-10 parts of EVA particles.

[0009] The reinforcing layer is prepared from the following raw materials in parts by weight: 7-12 parts of anti-aging modified masterbatch, 33-40 parts of linear low-density polyethylene particles, 15-21 parts of maleic anhydride grafted polyethylene particles and 4-5 parts of high-density polyethylene particles.

[0010] The black layer is prepared from the following raw materials in parts by weight: 8-12 parts of carbon black masterbatch, 77-83 parts of linear low-density polyethylene particles, 18-23 parts of anti-aging modified masterbatch and 7-9 parts of EVA particles.

[0011] The white light conversion functional masterbatch is prepared from the following raw materials in parts by weight: 62-70 parts of modified filler, 20-25 parts of composite light conversion agent, 5-7 parts of polyethylene wax, 1.5-2.5 parts of zinc stearate, 0.5-1 part of antioxidant 1010, 95-110 parts of linear low-density polyethylene powder and 3-4 parts of plasticizer.

[0012] The modified filler is prepared from the following raw materials in parts by weight: 70-90 parts of titanium white, 10-15 parts of nano zinc oxide, 2-4 parts of aluminate coupling agent and 0.1-0.2 parts of diethanolamine, and 200-300 parts of isopropyl alcohol.

[0013] The anti-aging modified masterbatch is prepared from the following raw materials in parts by weight: 30-35 parts of tetramethylpiperidinol, 20-24 parts of itaconic acid, 0.2-0.5 parts of dibutyltin dilaurate, 36-40 parts of light stabilizer UV-1130 and 30-40 parts of metallocene linear low-density polyethylene powder.

[0014] The composite light conversion agent is obtained by compounding a purple-to-red light conversion powder and a VTR-660 light conversion agent in a mass ratio of 1: (3-4). The purple-to-red light conversion powder is purchased from Shandong Qishun New Material Co., Ltd., and the VTR-660 light conversion agent is purchased from Changsha Xivesil Technology Co., Ltd.

[0015] The carbon black masterbatch is purchased from Qingzhou Xinming New Material Co., Ltd.

[0016] The aluminate coupling agent is isopropyl di-stearate oxy-aluminate.

[0017] The plasticizer is any one of diethylene glycol dibenzoate, tributyl citrate, dioctyl terephthalate.

[0018] A preparation method of black-and-white light conversion weed control mulch film, comprising the following steps:

[0019] S1, titanium dioxide, nano zinc oxide, diethanolamine, isopropanol, stirring to form a uniform mixture slurry, then adding aluminum coupling agent refluxing for 2-3h, the reaction liquid is spray dried, and the dried powder is collected to obtain the modified filler.

[0020] The weight ratio of the raw materials for preparing the modified filler is: titanium dioxide 70-90 parts, nano zinc oxide 10-15 parts, aluminum coupling agent 2-4 parts, diethanolamine 0.1-0.2 parts, and isopropanol 200-300 parts.

[0021] Further, the refluxing reaction has a reaction temperature of 75-80℃.

[0022] Further, the spray drying has an inlet air temperature of 160-200℃ and an outlet air temperature of 90-110℃.

[0023] Further, the titanium dioxide, nano zinc oxide, and diethanolamine are added to isopropanol and stirred and dispersed at room temperature for 30-60min to form a uniform slurry, then the aluminum coupling agent is added, stirring is maintained and the mixture is refluxed for 2-3h, and the reaction temperature is controlled at 75-80℃. The reaction liquid is evaporated using a spray drying device, the inlet air temperature is 160-200℃, the outlet air temperature is 90-110℃, and the dried powder is collected to obtain the modified filler.

[0024] S2, the low-density polyethylene powder is dried and preheated, zinc stearate, antioxidant 1010, composite light conversion agent, modified filler, plasticizer, and polyethylene wax are uniformly mixed, then the mixture is introduced into a banbury mixer for mixing and granulation to obtain a white light conversion functional masterbatch.

[0025] Further, the weight ratio of the raw materials for preparing the white light conversion functional masterbatch is: modified filler 62-70 parts, composite light conversion agent 20-25 parts, polyethylene wax 5-7 parts, zinc stearate 1.5-2.5 parts, antioxidant 1010 0.5-1 part, linear low-density polyethylene powder 95-110 parts, and plasticizer 3-4 parts.

[0026] Further, the composite light conversion agent is obtained by compounding purple-to-red light conversion powder and VTR-660 light conversion agent at a mass ratio of 1: (3-4).

[0027] Further, the drying and preheating is preheated in an oven at 70-80℃ for 2-4h.

[0028] Further, the mixing time is 10-15 min, the mixing temperature is controlled at 180-190 DEG C, and the rotating speed of the mixer is controlled at 90-110 r / min.

[0029] S3, tetramethylpiperidyl alcohol, itaconic acid is added to the reactor, and after replacing air, it is heated and melted, dibutyltin dilaurate is added, and the reaction is carried out under reduced pressure; the product of the reaction under reduced pressure is added to a double-screw extruder together with metallocene linear low-density polyethylene powder and light stabilizer UV-1130 for melt blending and granulation to obtain the anti-aging modified masterbatch.

[0030] Further, the anti-aging modified masterbatch is prepared from the following raw materials in parts by weight: tetramethylpiperidyl alcohol 30-35 parts, itaconic acid 20-24 parts, dibutyltin dilaurate 0.2-0.5 parts, light stabilizer UV-1130 36-40 parts, metallocene linear low-density polyethylene powder 30-40 parts.

[0031] Further, the air is replaced by nitrogen.

[0032] Further, the heating and melting is carried out by heating to 170-180 DEG C to form a homogeneous molten liquid.

[0033] Further, the reaction under reduced pressure is carried out under the condition of a pressure of less than -0.08 MPa, and the stirring is continued until the acid value of the system is less than or equal to 5 mgKOH / g.

[0034] Further, the melt blending is carried out at a temperature of 185-195 DEG C.

[0035] S4, the raw materials of the reflective layer, the reinforcing layer and the black layer are melt co-extruded respectively, and the extruded film is drawn, cooled, edge-cut and wound to obtain the finished black-and-white light-reflecting mulch film.

[0036] Further, the raw materials of the reflective layer include, in parts by weight: white light-reflecting functional masterbatch 14-18 parts, anti-aging modified masterbatch 10-15 parts, linear low-density polyethylene particles 50-60 parts, metallocene linear low-density polyethylene particles 25-33 parts, and EVA particles 6-10 parts.

[0037] Further, the raw materials of the reinforcing layer include, in parts by weight: anti-aging modified masterbatch 7-12 parts, linear low-density polyethylene particles 33-40 parts, maleic anhydride grafted polyethylene particles 15-21 parts, and high-density polyethylene particles 4-5 parts.

[0038] Further, the raw materials of the black layer include, in parts by weight: carbon black masterbatch 8-12 parts, linear low-density polyethylene particles 77-83 parts, anti-aging modified masterbatch 18-23 parts, and EVA particles 7-9 parts.

[0039] Further, the melt co-extrusion: the raw materials of each layer of the reflective layer, the reinforcing layer and the black layer are mixed respectively, and are added into the corresponding single screw extruder to melt, to form a melt, and the melt is extruded from the co-extrusion die through a co-extrusion distributor.

[0040] Further, the temperature control of the single screw extruder: the conveying section is 150-160 DEG C, the melting section is 175-185 DEG C, the mixing section is 180-195 DEG C, the homogenizing section is 180-200 DEG C, and the die temperature is 170-180 DEG C; and the screw rotation speed of the single screw extruder is 100-150 r / min.

[0041] The beneficial effects of the present application are as follows:

[0042] The tensile load of the black and white light conversion weed control mulch prepared by the present application is 5.1-5.6 N, the right angle tear load is 2.4-2.7 N, and the nominal strain at break is > 390%, which indicates that the mechanical properties are strong; after 300 h of light aging treatment, the tensile load retention rate is 92.3-96.1%, the right angle tear load retention rate is 88.9-92%, and the light transmittance is basically not affected, which indicates that the black and white light conversion weed control mulch provided by the present application also has good aging resistance. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 It is a physical photograph of example 1 of the present application.

[0044] Figure 2 It is a light conversion effect diagram of example 1 of the present application under a 365 nm light source.

[0045] Figure 3 It is a polymer FTIR analysis diagram in step S3 of example 1 of the present application. The polymer is analyzed, and the ether bond characteristic peak 1240 cm -1 , the ester group characteristic peak 1739 cm -1 , and the piperidine ring characteristic peak 1387 cm -1 are observed, so that it can be determined that the polymer containing a hindered amine structure is obtained after condensation of tetramethyl piperidinol and itaconic acid. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical scheme and advantages of the present application clearer, the embodiments of the present application will be further described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0047] Example 1: A black and white light conversion weed control mulch

[0048] A black and white light conversion weed control mulch has a three-layer structure of a reflective layer, a reinforcing layer and a black layer.

[0049] The black-and-white light conversion mulch is prepared by the following steps:

[0050] S1, titanium dioxide, nano zinc oxide, diethanolamine are added into isopropyl alcohol, stirred and dispersed at room temperature for 30 min to form a uniform slurry, then aluminate coupling agent is added, keep stirring and heat the mixture to 80℃, reflux for 3h. The reaction solution is evaporated by using a spray drying device, the inlet temperature of the spray drying device is 200℃, the outlet temperature is 100℃, and the dried powder is collected to obtain the modified filler.

[0051] The weight ratio of the raw materials of the modified filler is: titanium dioxide 90 parts, nano zinc oxide 10 parts, aluminate coupling agent 4 parts, diethanolamine 0.2 parts, isopropyl alcohol 300 parts.

[0052] S2, the linear low-density polyethylene powder is dried and preheated in an oven at 80℃ for 2h, and then added into a high-speed mixer, first stirred at a low speed of 400r / min, then zinc stearate, antioxidant 1010, composite light conversion agent, modified filler, and diethylene glycol dibenzoate are added in sequence, continue to stir for 5 min, finally add polyethylene wax, adjust the stirring speed to 1500r / min, and stir until there is no visible color difference or agglomeration in the material. The stirred material is added into an internal mixer, the internal mixing temperature is adjusted to 180℃, and the rotating speed is 110r / min, and the internal mixing is carried out for 10 min. The melt after internal mixing is water-cooled and granulated by a granulating device to obtain a white light conversion functional masterbatch.

[0053] The weight ratio of the raw materials of the white light conversion functional masterbatch is: modified filler 65 parts, composite light conversion agent 25 parts, polyethylene wax 7 parts, zinc stearate 2 parts, antioxidant 1010 0.5 parts, linear low-density polyethylene powder 110 parts, and diethylene glycol dibenzoate 4 parts.

[0054] The composite light conversion agent is obtained by compounding purple-to-red light conversion powder and VTR-660 light conversion agent at a mass ratio of 1:3.

[0055] S3, tetramethylpiperidinol and itaconic acid are added into a reactor, nitrogen is introduced to replace air, the temperature is increased to 170℃ at a rate of 5℃ / min to form a homogeneous molten liquid, and then dibutyltin dilaurate is added, and the reaction is carried out under the condition of vacuum degree < -0.08MPa. The acid value of the system is detected by sampling, and the reaction is stopped when the acid value is reduced to below 5mgKOH / g. A polymer containing a hindered amine structure is obtained. The obtained polymer is mixed with metallocene linear low-density polyethylene powder and light stabilizer UV-1130, and then added into a twin-screw extruder for melt blending and granulation to obtain an anti-aging modified masterbatch. During the melt blending process, the temperature of the whole section of the twin-screw extruder is controlled at 190℃.

[0056] The raw materials for preparing the anti-aging modified master batch include, by weight: tetramethylpiperidinol 35 parts, itaconic acid 24 parts, dibutyltin dilaurate 0.5 parts, light stabilizer UV-1130 40 parts, metallocene linear low-density polyethylene powder 40 parts.

[0057] S4, the raw materials of each layer of the reflective layer, the reinforcing layer and the black layer are mixed respectively, and each layer is added into a single screw extruder for melt mixing to form a melt, the temperature of each layer of the single screw extruder is controlled as follows: the conveying section is 160℃, the melting section is 175℃, the mixing section is 190℃, and the homogenizing section is 200℃, and the rod rotation speed is 120r / min. The melt passes through a co-extrusion distributor into a co-extrusion die head, extrudes a film, and the die head temperature is 180℃. The extruded film is cooled by traction, edge cutting and winding to obtain the finished black and white light-converting weed-inhibiting mulch film.

[0058] The raw materials of the reflective layer include, by weight: white light-converting functional master batch 15 parts, anti-aging modified master batch 10 parts, linear low-density polyethylene particles 60 parts, metallocene linear low-density polyethylene particles 25 parts, EVA particles 10 parts, and ethylene bis-stearamide 5 parts.

[0059] The raw materials of the reinforcing layer include, by weight: anti-aging modified master batch 10 parts, linear low-density polyethylene particles 35 parts, maleic anhydride grafted polyethylene particles 20 parts, ethylene bis-stearamide 4 parts, and high-density polyethylene particles 4 parts.

[0060] The raw materials of the black layer include, by weight: carbon black master batch 10 parts, linear low-density polyethylene particles 83 parts, anti-aging modified master batch 20 parts, EVA particles 9 parts, and ethylene bis-stearamide 5 parts.

[0061] Example 2: A black and white light-converting weed-inhibiting mulch film

[0062] A black and white light-converting weed-inhibiting mulch film has a three-layer structure of a reflective layer, a reinforcing layer and a black layer.

[0063] The black and white light-converting weed-inhibiting mulch film is prepared by the following steps:

[0064] S1, titanium white, nano zinc oxide and diethanolamine are added into isopropyl alcohol, stirred and dispersed at room temperature for 60 minutes to form a uniform slurry, then an aluminate coupling agent is added, stirring is maintained and the mixture is heated to 80℃, and refluxed for 2 hours. The reaction solution is evaporated using a spray drying device, the inlet air temperature is 180℃, the outlet air temperature is 90℃, and the dried powder is collected to obtain the modified filler.

[0065] The raw materials of the modified filler are in a weight ratio of: titanium white 80 parts, nano zinc oxide 10 parts, aluminat coupling agent 2 parts, diethanolamine 0.2 parts, and isopropyl alcohol 300 parts.

[0066] S2, the linear low density polyethylene powder is dried and preheated in an oven at 80℃ for 4h, and is added into a high-speed mixer, first stirring at a low speed of 300r / min, and then zinc stearate, antioxidant 1010, composite light conversion agent, modified filler, tributyl citrate are added in sequence, and stirring is continued for 5 min, and finally polyethylene wax is added, and stirring is adjusted to a high speed of 1300r / min, and the material is stirred until no visible color difference or agglomeration is observed, and then the stirred material is added into a banbury mixer, and the banbury temperature is adjusted to 180℃, and the rotating speed is 110r / min, and the melt is banburyed for 10 min, and then the melt is water-cooled and granulated by a granulating device to obtain a white light conversion functional masterbatch.

[0067] The raw material weight ratio of the white light conversion functional masterbatch is as follows: modified filler 70 parts, composite light conversion agent 25 parts, polyethylene wax 5 parts, zinc stearate 2.5 parts, antioxidant 1010 1 part, linear low density polyethylene powder 100 parts, and tributyl citrate 4 parts.

[0068] The composite light conversion agent is obtained by compounding a purple-to-red light conversion powder and a VTR-660 light conversion agent at a mass ratio of 1:3.

[0069] S3, tetramethylpiperidinol and itaconic acid are added into a reactor, nitrogen is introduced to replace air, the temperature is raised to 180℃ at a rate of 5℃ / min to form a homogeneous molten liquid, and dibutyltin dilaurate is added, and the reaction is carried out under a vacuum degree of pressure < -0.08MPa, and the acid value of the system is detected by sampling every 1h, and the reaction is stopped when the acid value of the system is reduced to below 5mgKOH / g, and a polymer containing a hindered amine structure is obtained. The obtained polymer is fully mixed with a metallocene linear low density polyethylene powder and a light stabilizer UV-1130, and is added into a twin-screw extruder for melt blending and granulation to obtain an anti-aging modified masterbatch. During the melt blending process, the temperature of the whole section of the twin-screw extruder is controlled to be 195℃.

[0070] The raw material weight ratio of the anti-aging modified masterbatch is as follows: tetramethylpiperidinol 30 parts, itaconic acid 20 parts, dibutyltin dilaurate 0.5 parts, light stabilizer UV-1130 36 parts, and metallocene linear low density polyethylene powder 40 parts.

[0071] S4, the raw materials of the reflective layer, the reinforcing layer and the black layer are mixed respectively, and are added into corresponding single-screw extruders for melt mixing to form a melt, and the temperature of the single-screw extruders of each layer is controlled to be 160℃ for the conveying section, 180℃ for the melting section, 180℃ for the mixing section, and 190℃ for the homogenizing section, and the screw rotating speed is 100r / min. The melt passes through a co-extrusion distributor to enter a co-extrusion die head, and a film is extruded, and the die head temperature is 170℃. The extruded film is cooled by traction, and is cut and wound to obtain a finished black-and-white light conversion weed control mulch film.

[0072] The reflective layer includes, by weight parts, white light conversion functional masterbatch 18 parts, anti-aging modified masterbatch 15 parts, linear low density polyethylene particles 50 parts, metallocene linear low density polyethylene particles 30 parts, EVA particles 6 parts, and ethylene bis-stearamide 5 parts.

[0073] The reinforcing layer includes, by weight parts, anti-aging modified masterbatch 12 parts, linear low density polyethylene particles 40 parts, maleic anhydride grafted polyethylene particles 21 parts, ethylene bis-stearamide 2 parts, and high density polyethylene particles 4 parts.

[0074] The black layer includes, by weight parts, carbon black masterbatch 8 parts, linear low density polyethylene particles 80 parts, anti-aging modified masterbatch 23 parts, EVA particles 7 parts, and ethylene bis-stearamide 5 parts.

[0075] Example 3: A black and white light conversion weed control mulch film

[0076] A black and white light conversion weed control mulch film has a three-layer structure of a reflective layer, a reinforcing layer, and a black layer.

[0077] The black and white light conversion weed control mulch film is prepared by the following steps:

[0078] S1, titanium dioxide, nano zinc oxide, and diethanolamine are added to isopropyl alcohol, stirred and dispersed at room temperature for 60 min to form a uniform slurry, then aluminate coupling agent is added, stirring is maintained and the mixture is heated to 75℃, and refluxed for 3h. The reaction solution is evaporated using a spray drying device, the inlet air temperature is 160℃, the outlet air temperature is 110℃, and the dried powder is collected to obtain the modified filler.

[0079] The weight parts of the raw materials of the modified filler are: titanium dioxide 70 parts, nano zinc oxide 15 parts, aluminate coupling agent 2 parts, diethanolamine 0.1 parts, and isopropyl alcohol 200 parts.

[0080] S2, linear low density polyethylene powder is dried and preheated in a 70℃ oven for 4h, and then added to a high-speed mixer, first stirring at a low speed of 500r / min, then adding zinc stearate, antioxidant 1010, composite light conversion agent, modified filler, and dioctyl terephthalate in sequence, continuing to stir for 5 min, finally adding polyethylene wax, adjusting the stirring speed to 1000r / min, and stirring until there is no visible color difference or agglomeration in the material. The stirred material is added to an internal mixer, the internal mixing temperature is adjusted to 190℃, the rotation speed is 90r / min, and internal mixing is performed for 15 min. The melt after internal mixing is water-cooled and granulated by a granulating device to obtain a white light conversion functional masterbatch.

[0081] The raw material weight ratio of the white light conversion functional master batch is: modified filler 62 parts, composite light conversion agent 20 parts, polyethylene wax 5 parts, zinc stearate 1.5 parts, antioxidant 1010 0.5 parts, linear low-density polyethylene powder 95 parts, dioctyl terephthalate 3 parts.

[0082] The composite light conversion agent is obtained by compounding the purple-to-red light conversion powder and the VTR-660 light conversion agent at a mass ratio of 1:4.

[0083] S3, tetramethylpiperidinol, itaconic acid is added to the reactor, nitrogen is introduced to replace air, the temperature is raised to 180℃ at a rate of 8℃ / min to form a homogeneous molten liquid, dibutyltin dilaurate is added, and the vacuum degree is controlled at less than-0.08MPa to perform a reduced-pressure reaction, the system acid value is detected by sampling every 1h, and the reaction is stopped when the system acid value is reduced to below 5mgKOH / g, to obtain a polymer containing a hindered amine structure. The obtained polymer is fully mixed with metallocene linear low-density polyethylene powder and light stabilizer UV-1130, and is added to a twin-screw extruder for melt blending and granulation to obtain an anti-aging modified master batch. During the melt blending process, the temperature of the twin-screw extruder is controlled at 185℃.

[0084] The raw material weight ratio of the anti-aging modified master batch is: tetramethylpiperidinol 35 parts, itaconic acid 22 parts, dibutyltin dilaurate 0.2 parts, light stabilizer UV-1130 36 parts, metallocene linear low-density polyethylene powder 30 parts.

[0085] S4, the raw materials of the reflective layer, the reinforcing layer and the black layer are respectively mixed, and are added to corresponding single-screw extruders for melt mixing to form a melt, the temperature of each single-screw extruder is controlled at 150℃ for conveying, 185℃ for melting, 195℃ for mixing and 180℃ for homogenizing, and the screw rotation speed is 150r / min. The melt passes through a co-extrusion distributor to enter a co-extrusion die, and a film is extruded, and the die temperature is 180℃. The extruded film is cooled by traction, edge cutting and winding to obtain a finished black-and-white light conversion weed control mulch film.

[0086] The reflective layer includes, by weight: white light conversion functional master batch 14 parts, anti-aging modified master batch 12 parts, linear low-density polyethylene particles 60 parts, metallocene linear low-density polyethylene particles 33 parts, EVA particles 6 parts, and ethylene bis-stearamide 4 parts.

[0087] The reinforcing layer includes, by weight: anti-aging modified master batch 7 parts, linear low-density polyethylene particles 33 parts, maleic anhydride grafted polyethylene particles 15 parts, ethylene bis-stearamide 2 parts, and high-density polyethylene particles 5 parts.

[0088] The raw materials of the black layer include, in parts by weight: carbon black master batch 12 parts, linear low density polyethylene particles 77 parts, anti-aging modified master batch 18 parts, EVA particles 7 parts, ethylene bis-stearamide 4 parts.

[0089] Performance test

[0090] The black and white light conversion weed control mulch films obtained in Examples 1-3 were subjected to performance tests, and the test results are shown in Table 1. The black and white light conversion weed control mulch films obtained in Examples 1-3 were subjected to light aging treatment, and were subjected to performance tests again, and the test results are shown in Table 2.

[0091] Test method: The black and white light conversion weed control mulch films were subjected to tensile load, breaking nominal strain, and right angle tear load tests according to the test methods provided in GB 13735-2017 “Polyethylene blown agricultural ground covering film”.

[0092] Light aging treatment method: The treatment method in “Plastics - Laboratory light source exposure test methods - Part 3: Fluorescent UV lamp” (GB / T 16422.3-2022) was used for aging treatment for 300h, simulating about 6 months of use time in natural environment; the aging lamp box parameters were set as: the irradiation wavelength of the fluorescent UV lamp was 340nm, the irradiation intensity was 0.55W / m 2 , the temperature was 60℃, and the relative humidity was 80%.

[0093] Light transmittance: The light transmittance of the mulch film was tested using a light transmittance instrument according to GB / T 2410-2008 “Determination of light transmittance and haze of transparent plastics”;

[0094] Table 1 Performance test results

[0095]

[0096] Table 2 Performance test results after light aging treatment

[0097]

[0098] From the analysis of the data in Table 1, it can be seen that the black and white light conversion weed control mulch film prepared by the present application has a tensile load of 5.1-5.6N, a right angle tear load of 2.4-2.7N, a breaking nominal strain of >390%, and a light transmittance of 0.1-0.2%, indicating that it has strong mechanical properties and high weed control effect.

[0099] According to the analysis of the data in Table 2, the tensile load of the mulch film after light aging treatment is 4.8-5.3 N, the right angle tear load is 2.2-2.4 N, and the light conversion efficiency is 48-51%. According to the calculation, compared with the mulch film without light aging treatment, the tensile load retention rate is 92.3-96.1%, the right angle tear load retention rate is 88.9-92%, and the light transmittance is basically not affected. The above results also show that the black and white light conversion weed control mulch film provided by the application also has good aging resistance.

[0100] Obviously, there are still many specific implementation methods that can be changed under the concept of the application, and it should be declared that any changes made under the inventive concept of the application will fall within the scope of protection of the application.

Claims

1. A method for preparing a black-to-white light-suppressing film, characterized in that: It comprises the following steps: S1, titanium dioxide, nano zinc oxide, diethanolamine, isopropanol into the formation of mixed slurry, then add aluminum coupling agent reflux reaction 2~3h, the reaction liquid is spray dried, and the modified filler is obtained; S2, the linear low density polyethylene powder is dried and preheated, zinc stearate, antioxidant 1010, composite light conversion agent, modified filler, plasticizer, polyethylene wax are mixed, and then the mixture is introduced into a banbury mixer for mixing and granulation to obtain a white light conversion functional masterbatch; the raw materials of the composite light conversion agent include purple-red light conversion powder and VTR-660 light conversion agent; The preparation raw materials of the modified filler are weighed and proportioned as follows: titanium dioxide 70~90 parts, nano zinc oxide 10~15 parts, aluminum coupling agent 2~4 parts, diethanolamine 0.1~0.2 parts, and isopropanol 200~300 parts; S3, tetramethylpiperidinol and itaconic acid are added to a reactor, the air is replaced, and then the temperature is raised for melting, then dibutyltin dilaurate is added, and the reaction is carried out under reduced pressure; the product of the reaction under reduced pressure is added to a double-screw extruder together with metallocene linear low density polyethylene powder and light stabilizer UV-1130 for melt blending and granulation to obtain an anti-aging modified masterbatch; S4, the raw materials of the reflective layer, the reinforcing layer and the black layer are melt co-extruded, the extruded film is drawn and cooled, the edges are cut, and then the film is wound to obtain a finished black and white light conversion weed control mulch film; The raw materials of the reflective layer include the white light conversion functional masterbatch and the anti-aging modified masterbatch; The raw materials of the reinforcing layer and the black layer both contain the anti-aging modified masterbatch; The raw materials of the white light conversion functional masterbatch are weighed and proportioned as follows: modified filler 62~70 parts, composite light conversion agent 20~25 parts, polyethylene wax 5~7 parts, zinc stearate 1.5~2.5 parts, antioxidant 1010 0.5~1 part, linear low density polyethylene powder 95~110 parts, and plasticizer 3~4 parts; The preparation raw materials of the anti-aging modified masterbatch are weighed and proportioned as follows: tetramethylpiperidinol 30~35 parts, itaconic acid 20~24 parts, dibutyltin dilaurate 0.2~0.5 parts, light stabilizer UV-1130 36~40 parts, and metallocene linear low density polyethylene powder 30~40 parts; The raw materials of the reflective layer are weighed and proportioned as follows: white light conversion functional masterbatch 14~18 parts, anti-aging modified masterbatch 10~15 parts, linear low density polyethylene particles 50~60 parts, metallocene linear low density polyethylene particles 25~33 parts, and EVA particles 6~10 parts; The raw materials of the reinforcing layer are weighed and proportioned as follows: anti-aging modified masterbatch 7~12 parts, linear low density polyethylene particles 33~40 parts, maleic anhydride grafted polyethylene particles 15~21 parts, and high density polyethylene particles 4~5 parts; The raw materials of the black layer are weighed and proportioned as follows: carbon black masterbatch 8~12 parts, linear low density polyethylene particles 77~83 parts, anti-aging modified masterbatch 18~23 parts, and EVA particles 7~9 parts.

2. The preparation method of the black-and-white light-converted weed control mulching film according to claim 1, characterized in that: The reflux reaction in step S1 is carried out at a temperature of 75~80℃; The spray drying is carried out by using a spray drying device to evaporate the solvent, and the inlet air temperature is controlled at 160~200℃ and the outlet air temperature is controlled at 90~110℃.

3. The preparation method of the black-and-white light-converted weed control mulching film according to claim 1, characterized in that: The drying preheating in step S2: preheating in an oven at 70-80℃ for 2-4h; the internal mixing: internal mixing time is 10-15min, controlling internal mixing temperature at 180-190℃, controlling internal mixer rotating speed at 90-110r / min.

4. The preparation method of the black-and-white light-converted weed control mulching film according to claim 1, characterized in that: The air replacement in step S3: replacing the air in the reactor with nitrogen; the temperature rising melting: rising temperature to 170-180℃ to form a homogeneous melt; the reduced pressure reaction: stirring under the condition of pressure < -0.08MPa until the acid value of the system is ≤5mgKOH / g; the melt blending: melt blending temperature is 185-195℃.

5. The preparation method of the black-and-white light-converted weed control mulching film according to claim 1, characterized in that: The melt co-extrusion in step S4: stirring the raw materials of the reflective layer, the reinforcing layer and the black layer respectively, and adding them into the corresponding single screw extruder to form a melt, and the melt is extruded from the co-extrusion die through a co-extrusion distributor.

6. The preparation method of the black-and-white light conversion weed control mulching film according to claim 5, characterized in that: The temperature control of the single screw extruder: conveying section 150-160℃, melting section 175-185℃, mixing section 180-195℃, homogenizing section 180-200℃, die temperature 170-180℃; the rotating speed of the screw of the single screw extruder is 100-150r / min.

7. A black and white light-transmitting weed-preventing mulching film, characterized by: Prepared by the method of any one of claims 1-6.

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