Preparation method of light conversion agricultural film

Abstract

The invention relates to the technical field of light conversion agricultural films, in particular to a preparation method of a light conversion agricultural film. A preparation method of a light conversion agricultural film comprises the following steps: S1, adding a light conversion agent and a matrix into an internal mixer, and carrying out internal mixing at 125-135 DEG C for 1-2 h to obtain a uniformly mixed bulk polymer melt; s2, adding the block-shaped polymer melt into a forced feeding machine, adjusting the temperature to 180-185 DEG C, and extruding a strip-shaped polymer by using a single-screw extruder; s3, the strip-shaped polymer is added into a granulator, the rotation frequency of the granulator is 20.00 Hz, and light conversion master batches are obtained; and S4, the light conversion master batch, the matrix and the auxiliary are mixed and added into a hopper of a film blowing machine, the temperatures of charging barrels of three temperature zones of the film blowing machine are 130 DEG C, 150 DEG C and 165 DEG C respectively, the temperature of a machine head is 160 DEG C, the rotation frequency of a screw rod is 12.00 Hz, the rolling rotation speed is 160 rpm, and the light conversion agricultural film is prepared.

Description

Technical Field

[0001] This invention relates to the field of light-converting agricultural film technology, and in particular to a method for preparing light-converting agricultural film. Background Technology

[0002] With the increasing global population, food supplies have become strained. The extensive use of pesticides and fertilizers has limited the potential for increased grain production, while simultaneously causing significant environmental pollution. Therefore, seeking alternative, less polluting, and more effective ways to increase yields is crucial. Using agricultural light-converting films to enhance plant photosynthesis is one such environmentally friendly and effective method. Light-converting films, by adding light-converting agents to polyethylene, polyvinyl chloride, and other greenhouse films that provide insulation, cold protection, wind protection, and rain protection, enhance light conversion. This improves the quality of light transmitted through the film, absorbing the violet and green light unnecessary for plant photosynthesis and emitting blue or red light, thus strengthening photosynthesis and promoting crop growth and development. This has a positive impact on plant growth, nutrient absorption, chlorophyll content, and agricultural product quality, ultimately improving crop quality and increasing yields.

[0003] The photostability of different light-converting agents directly affects their practical application value and influences the promotion and application of light-converting films. Currently, the main light-converting agents are divided into organic and inorganic agents. Organic fluorescent dyes, when used as light-converting agents in agricultural films, have good compatibility with resins and are relatively easy to form films. However, they are prone to oxidation and decomposition, have a short service life, low absorption and conversion efficiency of sunlight, and can affect the light transmittance of agricultural films. Their price and cost are also higher than inorganic light-converting agents.

[0004] To improve the performance of the light conversion film, inorganic and organic light conversion agents can be used in combination. This not only enhances the film's filtering and absorption of light at different wavelengths, resulting in a more suitable transmission wavelength, but also reduces the weakening effect of a single inorganic agent on the film's strength. Furthermore, to give the film some heat-insulating properties, a certain amount of hydrotalcite needs to be added. This hydrotalcite blocks infrared rays, thus achieving a heat-insulating effect. Hydrotalcite can also improve the film's durability to some extent, slowing down the decay of its light conversion performance. However, because hydrotalcite is hygroscopic, when used in combination with hygroscopic metal sulfide-based inorganic light conversion agents, the film's lifespan in humid environments will be significantly reduced.

[0005] This invention aims to provide an advanced solution that replaces traditional rare-earth luminescent materials with environmentally friendly carbon-based nanomaterials. This solution is not dependent on rare earth, a strategic mineral resource, and has a more secure supply chain. Furthermore, the entire preparation process is more green and sustainable. Summary of the Invention

[0006] To address the problems mentioned in the background section, this invention provides a method for preparing light-converting agricultural film.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A method for preparing a light-converting agricultural film includes the following steps:

[0009] S1. Add the brightening agent and matrix to the internal mixer and mix at 125-135℃ for 1-2 hours to obtain a uniformly mixed block polymer melt.

[0010] S2. Add the block polymer melt to the forced feeder, adjust the temperature to 180-185℃, and extrude the strip polymer using a single screw extruder;

[0011] S3. Add the strip polymer to a pelletizer with a rotation frequency of 20.00 Hz to obtain optical conversion masterbatch;

[0012] S4. Mix the light-converting masterbatch, matrix and additives, and add them to the hopper of the blown film machine. The temperature of the material cylinder in the three temperature zones of the blown film machine is 130℃, 150℃ and 165℃ respectively, the temperature of the die head is 160℃, the rotation frequency of the screw is 12.00Hz and the winding speed is 160rpm to prepare the light-converting agricultural film.

[0013] Preferably, the method for preparing the light-converting agent includes the following steps:

[0014] S1-1. Take graphene and add it to a 1% chitosan acetic acid solution (acetic acid concentration 1%, pH 3-4), and ultrasonically disperse for 30-45 minutes (power 300W, frequency 40kHz) to form a uniform suspension.

[0015] S1-2. Add modified carbon quantum dot powder to the suspension and continue sonication for 15-30 minutes to obtain a dispersion.

[0016] S1-3. Add chitosan powder to the above dispersion and stir magnetically at 30-40℃ for 1-2 hours (300 r / min) until the powder is completely dissolved.

[0017] Add corn starch and citric acid, and continue stirring for 30-45 minutes to prepare a mixture (citric acid also acts as a cross-linking agent to promote the hydroxyl reaction between chitosan and starch).

[0018] S1-4. Add dilute alkali solution dropwise to the above mixture while continuously stirring magnetically to adjust the pH value to 7-9. Pour the adjusted mixture into a horizontal glass plate mold, control the thickness to 0.1-0.2 mm with a scraper, let it stand at room temperature for 1-2 hours, then transfer it to a vacuum drying oven and vacuum dry at 45℃ for 4.5 hours (vacuum degree -0.08MPa, to avoid high temperature causing fluorescence decay of carbon quantum dots).

[0019] S1-5. After drying, remove the membrane and soak it in deionized water (25℃) for 1-2 hours (to wash away unreacted citric acid and acetic acid), then air dry at room temperature for 20-24 hours to obtain the light conversion agent.

[0020] Preferably, the preparation method of the modified carbon quantum dot powder includes the following steps:

[0021] Citric acid and deionized water were mixed and magnetically stirred until dissolved. The mixture was then transferred to a polytetrafluoroethylene reactor and hydrothermally reacted at 170-190℃ for 3-4 hours. After the reaction, the mixture was allowed to cool naturally to room temperature. The supernatant was collected by centrifugation (8000 r / min, 10 min). Dilute sodium hydroxide solution was added dropwise to the supernatant to adjust the pH to 9-10. KH550 was then added, and the mixture was stirred at 50-60℃ for 1-2 hours. After freeze-drying, modified carbon quantum dot powder was obtained. The amino groups of the silane coupling agent reacted with the hydroxyl groups on the surface of the carbon quantum dots, improving their dispersibility in the chitosan matrix.

[0022] Preferably, the matrix is ​​at least one selected from low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, high-density polyethylene, polypropylene, and ethylene-vinyl acetate resin.

[0023] Preferably, the additive is at least one selected from polyethylene wax, vinyl bis-stearamide, zinc stearate, pentaerythritol stearate, titanate coupling agent, and aluminate coupling agent.

[0024] A light-converting agricultural film prepared by the aforementioned preparation method.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] 1. The light-converting agent prepared in this invention uses KH550 surface-modified carbon quantum dots (CQDs) as the core, and is loaded onto a stable composite matrix formed by a chitosan-graphene-citric acid crosslinked network to form a solid film-like light-converting agent; and uses CQDs / graphene as the core and a crosslinked chitosan-starch network as the shell. This shell not only solves the dispersion and compatibility problems, but also plays a protective and fixing role. The light-converting agent is well dispersed in the matrix and firmly bonded to the matrix, avoiding stress defects caused by agglomeration, thereby ensuring the tensile strength and tear strength of the agricultural film.

[0027] 2. In this invention, the biopolymer matrix coats the CQDs, effectively isolating them from external environmental factors (such as oxygen and humidity) and high processing temperatures that could damage their fluorescence properties. The CQDs and graphene are locked within a cross-linked network, preventing their migration and precipitation from the agricultural film during subsequent processing or use. Although CS / starch is hydrophilic, its surface polarity is reduced after cross-linking and subsequent washing. More importantly, the prior modification with KH550 has already given the CQDs a PE-compatible coating, improving the interfacial compatibility between the entire light-converting agent particle and PE. Simultaneously, the addition of graphene not only enhances mechanical properties, but its excellent thermal conductivity may also contribute to the thermal uniformity of the agricultural film during processing and use. Detailed Implementation

[0028] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Unless otherwise specified, the raw materials used in this invention are all from commercially available conventional products.

[0030] The graphene was purchased from Zhengzhou Wanchuang Chemical Products Co., Ltd., CAS No.: 7782-42-5;

[0031] Chitosan powder was purchased from Xi'an Weisbo Biotechnology Co., Ltd., CAS No.: 9012-76-4;

[0032] KH550 was purchased from Shandong Shuntai New Materials Co., Ltd., CAS No.: 919-30-2.

[0033] Preparation Example 1

[0034] The preparation method of the modified carbon quantum dot powder includes the following steps:

[0035] Mix 5g of citric acid with 50mL of deionized water, stir magnetically until dissolved, and then transfer to a polytetrafluoroethylene reactor. React hydrothermally at 170℃ for 3h. After the reaction, allow to cool naturally to room temperature, centrifuge (8000r / min, 10min) to collect the supernatant, and add 1M dilute sodium hydroxide solution dropwise to the supernatant to adjust the pH to 9. Then add 0.5g of KH550, stir at 50℃ for 1h, and freeze-dry to obtain modified carbon quantum dot powder.

[0036] The preparation method of the light-converting agent includes the following steps:

[0037] S1-1. Take 0.5g of graphene and add it to 100mL of 1% chitosan acetic acid solution (acetic acid concentration 1%, pH 3), and ultrasonically disperse for 30min (power 300W, frequency 40kHz) to form a uniform suspension.

[0038] S1-2. Add 1g of the modified carbon quantum dot powder to the suspension and continue sonication for 15min to obtain a dispersion.

[0039] S1-3. Add 5g of chitosan powder to the above dispersion and stir magnetically at 30°C for 1 hour (300r / min) until the powder is completely dissolved.

[0040] Add 10g of corn starch and 3g of citric acid, and continue stirring for 30 minutes to prepare the mixture.

[0041] S1-4. Add 1M sodium hydroxide solution dropwise to the above mixture while continuously stirring magnetically to adjust the pH value to 7. Pour the adjusted mixture into a horizontal glass plate mold, control the thickness to 0.1mm with a scraper, let it stand at room temperature for 1 hour, transfer it to a vacuum drying oven, and vacuum dry at 45℃ for 4.5 hours with a vacuum degree of -0.08MPa.

[0042] S1-5. After drying, remove the membrane and soak it in deionized water at 25℃ for 1 hour, then let it air dry at room temperature for 20 hours to obtain the light conversion agent.

[0043] Preparation Example 2

[0044] The preparation method of the modified carbon quantum dot powder includes the following steps:

[0045] Mix 6g of citric acid with 55mL of deionized water, stir magnetically until dissolved, and then transfer to a polytetrafluoroethylene reactor. React hydrothermally at 180℃ for 3h. After the reaction, allow to cool naturally to room temperature, centrifuge (8000r / min, 10min) to collect the supernatant, and add 1M dilute sodium hydroxide solution dropwise to the supernatant to adjust the pH to 9. Then add 0.5g of KH550, stir at 50℃ for 1h, and freeze-dry to obtain modified carbon quantum dot powder.

[0046] The preparation method of the light-converting agent includes the following steps:

[0047] S1-1. Take 0.5g of graphene and add it to 100mL of 1% chitosan acetic acid solution (acetic acid concentration 1%, pH 3), and ultrasonically disperse for 35min at 300W power and 40kHz frequency to form a uniform suspension.

[0048] S1-2. Add 2g of the modified carbon quantum dot powder to the suspension and continue sonication for 20min to obtain a dispersion.

[0049] S1-3. Add 6g of chitosan powder to the above dispersion and stir magnetically at 30°C for 1 hour (300r / min) until the powder is completely dissolved.

[0050] Add 10g of corn starch and 3g of citric acid, and continue stirring for 30 minutes to prepare the mixture.

[0051] S1-4. Add 1M sodium hydroxide solution dropwise to the above mixture while continuously stirring magnetically to adjust the pH value to 8. Pour the adjusted mixture into a horizontal glass plate mold, control the thickness to 0.1mm with a scraper, let it stand at room temperature for 1 hour, transfer it to a vacuum drying oven, and vacuum dry at 45℃ for 4.5 hours with a vacuum degree of -0.08MPa.

[0052] S1-5. After drying, remove the membrane and soak it in deionized water at 25℃ for 1 hour, then let it air dry at room temperature for 20 hours to obtain the light conversion agent.

[0053] Preparation Example 3

[0054] The preparation method of the modified carbon quantum dot powder includes the following steps:

[0055] Mix 7g of citric acid with 55mL of deionized water, stir magnetically until dissolved, and then transfer to a polytetrafluoroethylene reactor. React hydrothermally at 190℃ for 4h. After the reaction, allow to cool naturally to room temperature, centrifuge (8000r / min, 10min) to collect the supernatant, and add 1M dilute sodium hydroxide solution dropwise to the supernatant to adjust the pH to 9. Then add 0.8g of KH550, stir at 55℃ for 2h, and freeze-dry to obtain modified carbon quantum dot powder.

[0056] The preparation method of the light-converting agent includes the following steps:

[0057] S1-1. Take 0.5g of graphene and add it to 100mL of 1% chitosan acetic acid solution (acetic acid concentration 1%, pH 4), and ultrasonically disperse for 30min (power 300W, frequency 40kHz) to form a uniform suspension.

[0058] S1-2. Add 3g of the modified carbon quantum dot powder to the suspension and continue sonication for 15min to obtain a dispersion.

[0059] S1-3. Add 5g of chitosan powder to the above dispersion and stir magnetically at 30°C for 1 hour (300r / min) until the powder is completely dissolved.

[0060] Add 10g of corn starch and 3g of citric acid, and continue stirring for 30 minutes to prepare the mixture.

[0061] S1-4. Add 1M sodium hydroxide solution dropwise to the above mixture while continuously stirring magnetically to adjust the pH value to 9. Pour the adjusted mixture into a horizontal glass plate mold, control the thickness to 0.1mm with a scraper, let it stand at room temperature for 1 hour, transfer it to a vacuum drying oven, and vacuum dry at 45℃ for 4.5 hours with a vacuum degree of -0.08MPa.

[0062] S1-5. After drying, remove the membrane and soak it in deionized water at 25℃ for 1 hour, then let it air dry at room temperature for 20 hours to obtain the light conversion agent.

[0063] Preparation Example 4

[0064] The preparation method of the modified carbon quantum dot powder includes the following steps:

[0065] Mix 8g of citric acid with 60mL of deionized water, stir magnetically until dissolved, and then transfer to a polytetrafluoroethylene reactor. React hydrothermally at 190℃ for 4h. After the reaction, allow to cool naturally to room temperature, centrifuge (8000r / min, 10min) to collect the supernatant, and add 1M dilute sodium hydroxide solution dropwise to the supernatant to adjust the pH to 9.5. Then add 1g of KH550, stir at 60℃ for 2h, and freeze-dry to obtain modified carbon quantum dot powder.

[0066] The preparation method of the light-converting agent includes the following steps:

[0067] S1-1. Take 0.5g of graphene and add it to 100mL of 1% chitosan acetic acid solution (acetic acid concentration 1%, pH 3), and ultrasonically disperse for 30min (power 300W, frequency 40kHz) to form a uniform suspension.

[0068] S1-2. Add 1g of the modified carbon quantum dot powder to the suspension and continue sonication for 15min to obtain a dispersion.

[0069] S1-3. Add 5g of chitosan powder to the above dispersion and stir magnetically at 30°C for 1 hour (300r / min) until the powder is completely dissolved.

[0070] Add 10g of corn starch and 3g of citric acid, and continue stirring for 30 minutes to prepare the mixture.

[0071] S1-4. Add 1M sodium hydroxide solution dropwise to the above mixture while continuously stirring magnetically to adjust the pH value to 7. Pour the adjusted mixture into a horizontal glass plate mold, control the thickness to 0.1mm with a scraper, let it stand at room temperature for 1 hour, transfer it to a vacuum drying oven, and vacuum dry at 45℃ for 4.5 hours with a vacuum degree of -0.08MPa.

[0072] S1-5. After drying, remove the membrane and soak it in deionized water at 25℃ for 1 hour, then let it air dry at room temperature for 20 hours to obtain the light conversion agent.

[0073] Preparation Example 5

[0074] The preparation method of the modified carbon quantum dot powder includes the following steps:

[0075] Mix 8g of citric acid with 55mL of deionized water, stir magnetically until dissolved, and then transfer to a polytetrafluoroethylene reactor. React hydrothermally at 185℃ for 4 hours. After the reaction, allow to cool naturally to room temperature, centrifuge (8000r / min, 10min) to collect the supernatant, and add 1M dilute sodium hydroxide solution dropwise to the supernatant to adjust the pH to 9.5. Then add 1g of KH550, stir at 50℃ for 1 hour, and freeze-dry to obtain modified carbon quantum dot powder.

[0076] The preparation method of the light-converting agent includes the following steps:

[0077] S1-1. Take 0.5g of graphene and add it to 100mL of 1% chitosan acetic acid solution (acetic acid concentration 1%, pH 3), and ultrasonically disperse for 40min (power 300W, frequency 40kHz) to form a uniform suspension.

[0078] S1-2. Add 2g of the modified carbon quantum dot powder to the suspension and continue sonication for 25min to obtain a dispersion.

[0079] S1-3. Add 8g of chitosan powder to the above dispersion and stir magnetically at 35°C for 1 hour (300r / min) until the powder is completely dissolved.

[0080] Add 15g of corn starch and 3g of citric acid, and continue stirring for 35 minutes to prepare the mixture.

[0081] S1-4. Add 1M sodium hydroxide solution dropwise to the above mixture while continuously stirring magnetically to adjust the pH value to 8. Pour the adjusted mixture into a horizontal glass plate mold, control the thickness to 0.2mm with a scraper, let it stand at room temperature for 1 hour, transfer it to a vacuum drying oven, and vacuum dry at 45℃ for 4.5 hours with a vacuum degree of -0.08MPa.

[0082] S1-5. After drying, remove the membrane and soak it in deionized water at 25℃ for 1 hour, then let it air dry at room temperature for 20 hours to obtain the light conversion agent.

[0083] Preparation Example 6

[0084] The preparation method of the modified carbon quantum dot powder includes the following steps:

[0085] Mix 7g of citric acid with 55mL of deionized water, stir magnetically until dissolved, and then transfer to a polytetrafluoroethylene reactor. React hydrothermally at 190℃ for 4h. After the reaction, allow to cool naturally to room temperature, centrifuge (8000r / min, 10min) to collect the supernatant, and add 1M dilute sodium hydroxide solution dropwise to the supernatant to adjust the pH to 9.5. Then add 1g of KH550, stir at 60℃ for 2h, and freeze-dry to obtain modified carbon quantum dot powder.

[0086] The preparation method of the light-converting agent includes the following steps:

[0087] S1-1. Take 0.5g of graphene and add it to 100mL of 1% chitosan acetic acid solution (acetic acid concentration 1%, pH 3), and ultrasonically disperse for 45min (power 300W, frequency 40kHz) to form a uniform suspension.

[0088] S1-2. Add 3g of the modified carbon quantum dot powder to the suspension and continue sonication for 25min to obtain a dispersion.

[0089] S1-3. Add 5g of chitosan powder to the above dispersion and stir magnetically at 30°C for 1 hour (300r / min) until the powder is completely dissolved.

[0090] Add 15g corn starch and 4g citric acid, and continue stirring for 30 minutes to prepare the mixture.

[0091] S1-4. Add 1M sodium hydroxide solution dropwise to the above mixture while continuously stirring magnetically to adjust the pH value to 9. Pour the adjusted mixture into a horizontal glass plate mold, control the thickness to 0.1mm with a scraper, let it stand at room temperature for 1 hour, transfer it to a vacuum drying oven, and vacuum dry at 45℃ for 4.5 hours with a vacuum degree of -0.08MPa.

[0092] S1-5. After drying, remove the membrane and soak it in deionized water at 25℃ for 1 hour, then let it air dry at room temperature for 20 hours to obtain the light conversion agent.

[0093] Preparation Example 7

[0094] The preparation method of the modified carbon quantum dot powder includes the following steps:

[0095] Mix 6g of citric acid with 50mL of deionized water, stir magnetically until dissolved, and then transfer to a polytetrafluoroethylene reactor. React hydrothermally at 180℃ for 3h. After the reaction, allow to cool naturally to room temperature, centrifuge (8000r / min, 10min) to collect the supernatant, and add 1M dilute sodium hydroxide solution dropwise to the supernatant to adjust the pH to 10. Then add 0.8g of KH550, stir at 50℃ for 2h, and freeze-dry to obtain modified carbon quantum dot powder.

[0096] The preparation method of the light-converting agent includes the following steps:

[0097] S1-1. Take 0.5g of graphene and add it to 100mL of 1% chitosan acetic acid solution (acetic acid concentration 1%, pH 3), and ultrasonically disperse for 30min (power 300W, frequency 40kHz) to form a uniform suspension.

[0098] S1-2. Add 2g of the modified carbon quantum dot powder to the suspension and continue sonication for 15min to obtain a dispersion.

[0099] S1-3. Add 5g of chitosan powder to the above dispersion and stir magnetically at 30°C for 1 hour (300r / min) until the powder is completely dissolved.

[0100] Add 10g of corn starch and 3g of citric acid, and continue stirring for 30 minutes to prepare the mixture.

[0101] S1-4. Add 1M sodium hydroxide solution dropwise to the above mixture while continuously stirring magnetically to adjust the pH value to 7. Pour the adjusted mixture into a horizontal glass plate mold, control the thickness to 0.1mm with a scraper, let it stand at room temperature for 1 hour, transfer it to a vacuum drying oven, and vacuum dry at 45℃ for 4.5 hours with a vacuum degree of -0.08MPa.

[0102] S1-5. After drying, remove the membrane and soak it in deionized water at 25℃ for 1 hour, then let it air dry at room temperature for 20 hours to obtain the light conversion agent.

[0103] Preparation Example 8

[0104] The preparation method of the modified carbon quantum dot powder includes the following steps:

[0105] Mix 8g of citric acid with 60mL of deionized water, stir magnetically until dissolved, and then transfer to a polytetrafluoroethylene reactor. React hydrothermally at 190℃ for 4h. After the reaction, allow to cool naturally to room temperature, centrifuge (8000r / min, 10min) to collect the supernatant, and add 1M dilute sodium hydroxide solution dropwise to the supernatant to adjust the pH to 10. Then add 1g of KH550, stir at 60℃ for 2h, and freeze-dry to obtain modified carbon quantum dot powder.

[0106] The preparation method of the light-converting agent includes the following steps:

[0107] S1-1. Take 0.5g of graphene and add it to 100mL of 1% chitosan acetic acid solution (acetic acid concentration 1%, pH 3), and ultrasonically disperse for 30min (power 300W, frequency 40kHz) to form a uniform suspension.

[0108] S1-2. Add 3g of the modified carbon quantum dot powder to the suspension and continue sonication for 30min to obtain a dispersion.

[0109] S1-3. Add 8g of chitosan powder to the above dispersion and stir magnetically at 40°C for 2 hours (300r / min) until the powder is completely dissolved.

[0110] Add 20g corn starch and 5g citric acid, and continue stirring for 30 minutes to prepare the mixture.

[0111] S1-4. Add 1M sodium hydroxide solution dropwise to the above mixture while continuously stirring magnetically to adjust the pH value to 8. Pour the adjusted mixture into a horizontal glass plate mold, control the thickness to 0.1mm with a scraper, let it stand at room temperature for 1 hour, transfer it to a vacuum drying oven, and vacuum dry at 45℃ for 4.5 hours with a vacuum degree of -0.08MPa.

[0112] S1-5. After drying, remove the membrane and soak it in deionized water at 25℃ for 1 hour, then let it air dry at room temperature for 20 hours to obtain the light conversion agent.

[0113] Preparation Example 9

[0114] The preparation method of the modified carbon quantum dot powder includes the following steps:

[0115] Mix 8g of citric acid with 55mL of deionized water, stir magnetically until dissolved, and then transfer to a polytetrafluoroethylene reactor. React hydrothermally at 185℃ for 4 hours. After the reaction, allow to cool naturally to room temperature, centrifuge (8000r / min, 10min) to collect the supernatant, and add 1M dilute sodium hydroxide solution dropwise to the supernatant to adjust the pH to 10. Then add 1g of KH550, stir at 60℃ for 1 hour, and freeze-dry to obtain modified carbon quantum dot powder.

[0116] The preparation method of the light-converting agent includes the following steps:

[0117] S1-1. Take 0.5g of graphene and add it to 100mL of 1% chitosan acetic acid solution (acetic acid concentration 1%, pH 3), and ultrasonically disperse for 30min (power 300W, frequency 40kHz) to form a uniform suspension.

[0118] S1-2. Add 1g of the modified carbon quantum dot powder to the suspension and continue sonication for 15min to obtain a dispersion.

[0119] S1-3. Add 5g of chitosan powder to the above dispersion and stir magnetically at 30°C for 1 hour (300r / min) until the powder is completely dissolved.

[0120] Add 18g of corn starch and 4g of citric acid, and continue stirring for 30 minutes to prepare the mixture.

[0121] S1-4. Add 1M sodium hydroxide solution dropwise to the above mixture while continuously stirring magnetically to adjust the pH value to 9. Pour the adjusted mixture into a horizontal glass plate mold, control the thickness to 0.1mm with a scraper, let it stand at room temperature for 1 hour, transfer it to a vacuum drying oven, and vacuum dry at 45℃ for 4.5 hours with a vacuum degree of -0.08MPa.

[0122] S1-5. After drying, remove the membrane and soak it in deionized water at 25℃ for 2 hours, then let it air dry at room temperature for 24 hours to obtain the light conversion agent.

[0123] Example 1

[0124] A method for preparing a light-converting agricultural film includes the following steps:

[0125] S1. Add 1g of the light-converting agent prepared in Preparation Example 1 and 50g of low-density polyethylene to a mixer and mix at 125°C for 1 hour to obtain a uniformly mixed block polymer melt.

[0126] S2. Add the block polymer melt to the forced feeder, adjust the temperature to 180℃, and extrude the strip polymer using a single screw extruder;

[0127] S3. Add the strip polymer to a pelletizer with a rotation frequency of 20.00 Hz to obtain optical conversion masterbatch;

[0128] S4. Mix 2g of light-converting masterbatch, 50g of low-density polyethylene and 1g of polyethylene wax, and add them to the hopper of the blown film machine. The temperature of the material cylinder in the three temperature zones of the blown film machine is 130℃, 150℃ and 165℃ respectively, the temperature of the die head is 160℃, the rotation frequency of the screw is 12.00Hz and the winding speed is 160rpm to prepare light-converting agricultural film.

[0129] Example 2

[0130] A method for preparing a light-converting agricultural film includes the following steps:

[0131] S1. Add 1g of the light-converting agent prepared in Preparation Example 2 and 50g of linear low-density polyethylene to a mixer and mix at 125°C for 2 hours to obtain a uniformly mixed block polymer melt.

[0132] S2. Add the block polymer melt to the forced feeder, adjust the temperature to 185℃, and extrude the strip polymer using a single screw extruder;

[0133] S3. Add the strip polymer to a pelletizer with a rotation frequency of 20.00 Hz to obtain optical conversion masterbatch;

[0134] S4. Mix 3g of light-converting masterbatch, 50g of linear low-density polyethylene and 1.5g of vinyl bis-stearamide, and add them to the hopper of the blown film machine. The temperature of the blown film machine's three-temperature zone barrel is 130℃, 150℃ and 165℃, the die head temperature is 160℃, the screw rotation frequency is 12.00Hz and the winding speed is 160rpm to prepare light-converting agricultural film.

[0135] Example 3

[0136] A method for preparing a light-converting agricultural film includes the following steps:

[0137] S1. Add 1.5g of the light-converting agent prepared in Preparation Example 3 and 50g of medium-density polyethylene to a mixer and mix at 135°C for 2 hours to obtain a uniformly mixed block polymer melt.

[0138] S2. Add the block polymer melt to the forced feeder, adjust the temperature to 185℃, and extrude the strip polymer using a single screw extruder;

[0139] S3. Add the strip polymer to a pelletizer with a rotation frequency of 20.00 Hz to obtain optical conversion masterbatch;

[0140] S4. Mix 4g of light-converting masterbatch, 50g of medium-density polyethylene and 2g of vinyl bis-stearamide, and add them to the hopper of the blown film machine. The temperature of the blown film machine's three-temperature zone barrel is 130℃, 150℃ and 165℃, the die head temperature is 160℃, the screw rotation frequency is 12.00Hz and the winding speed is 160rpm to prepare light-converting agricultural film.

[0141] Example 4

[0142] A method for preparing a light-converting agricultural film includes the following steps:

[0143] S1. Add 1.5g of the light-converting agent prepared in Preparation Example 4 and 50g of high-density polyethylene to a mixer and mix at 135°C for 2 hours to obtain a uniformly mixed block polymer melt.

[0144] S2. Add the block polymer melt to the forced feeder, adjust the temperature to 185℃, and extrude the strip polymer using a single screw extruder;

[0145] S3. Add the strip polymer to a pelletizer with a rotation frequency of 20.00 Hz to obtain optical conversion masterbatch;

[0146] S4. Mix 3g of light-converting masterbatch, 50g of high-density polyethylene and 1.5g of zinc stearate, and add them to the hopper of the blown film machine. The temperature of the material cylinder in the three temperature zones of the blown film machine is 130℃, 150℃ and 165℃ respectively, the temperature of the die head is 160℃, the rotation frequency of the screw is 12.00Hz and the winding speed is 160rpm to prepare the light-converting agricultural film.

[0147] Example 5

[0148] A method for preparing a light-converting agricultural film includes the following steps:

[0149] S1. Add 1.5g of the light-converting agent prepared in Preparation Example 5 and 50g of polypropylene to a mixer and mix at 135°C for 1 hour to obtain a uniformly mixed block polymer melt.

[0150] S2. Add the block polymer melt to the forced feeder, adjust the temperature to 180℃, and extrude the strip polymer using a single screw extruder;

[0151] S3. Add the strip polymer to a pelletizer with a rotation frequency of 20.00 Hz to obtain optical conversion masterbatch;

[0152] S4. Mix 4g of light-converting masterbatch, 50g of polypropylene and 1g of pentaerythritol stearate, and add them to the hopper of the blown film machine. The temperature of the blown film machine's three-temperature zone barrel is 130℃, 150℃ and 165℃, the die head temperature is 160℃, the screw rotation frequency is 12.00Hz and the winding speed is 160rpm to prepare light-converting agricultural film.

[0153] Example 6

[0154] A method for preparing a light-converting agricultural film includes the following steps:

[0155] S1. Add 1.5g of the light-converting agent prepared in Preparation Example 6 and 50g of ethylene-vinyl acetate resin to a mixer and mix at 130°C for 1 hour to obtain a uniformly mixed block polymer melt.

[0156] S2. Add the block polymer melt to the forced feeder, adjust the temperature to 185℃, and extrude the strip polymer using a single screw extruder;

[0157] S3. Add the strip polymer to a pelletizer with a rotation frequency of 20.00 Hz to obtain optical conversion masterbatch;

[0158] S4. Mix 3g of light-converting masterbatch, 50g of ethylene-vinyl acetate resin and 1g of titanate coupling agent, and add them to the hopper of the blown film machine. The temperature of the material cylinder in the three temperature zones of the blown film machine is 130℃, 150℃ and 165℃ respectively, the temperature of the die head is 160℃, the rotation frequency of the screw is 12.00Hz and the winding speed is 160rpm to prepare light-converting agricultural film.

[0159] Example 7

[0160] A method for preparing a light-converting agricultural film includes the following steps:

[0161] S1. Add 1g of the light-converting agent prepared in Preparation Example 7 and 50g of high-density polyethylene to a mixer and mix at 135°C for 2 hours to obtain a uniformly mixed block polymer melt.

[0162] S2. Add the block polymer melt to the forced feeder, adjust the temperature to 185℃, and extrude the strip polymer using a single screw extruder;

[0163] S3. Add the strip polymer to a pelletizer with a rotation frequency of 20.00 Hz to obtain optical conversion masterbatch;

[0164] S4. Mix 3g of light-converting masterbatch, 50g of high-density polyethylene and 2g of aluminate coupling agent, and add them to the hopper of the blown film machine. The temperature of the material cylinder in the three temperature zones of the blown film machine is 130℃, 150℃ and 165℃ respectively, the temperature of the die head is 160℃, the rotation frequency of the screw is 12.00Hz and the winding speed is 160rpm to prepare the light-converting agricultural film.

[0165] Example 8

[0166] A method for preparing a light-converting agricultural film includes the following steps:

[0167] S1. Add 1g of the light-converting agent prepared in Preparation Example 8 and 50g of polypropylene to a mixer and mix at 130°C for 2 hours to obtain a uniformly mixed block polymer melt.

[0168] S2. Add the block polymer melt to the forced feeder, adjust the temperature to 185℃, and extrude the strip polymer using a single screw extruder;

[0169] S3. Add the strip polymer to a pelletizer with a rotation frequency of 20.00 Hz to obtain optical conversion masterbatch;

[0170] S4. Mix 3g of light-converting masterbatch, 50g of polypropylene and 1g of aluminate coupling agent, and add them to the hopper of the blown film machine. The temperature of the material cylinder in the three temperature zones of the blown film machine is 130℃, 150℃ and 165℃ respectively, the temperature of the die head is 160℃, the rotation frequency of the screw is 12.00Hz and the winding speed is 160rpm to prepare light-converting agricultural film.

[0171] Example 9

[0172] A method for preparing a light-converting agricultural film includes the following steps:

[0173] S1. Add 1.5g of the light-converting agent prepared in Preparation Example 9 and 50g of linear low-density polyethylene to a mixer and mix at 125°C for 1 hour to obtain a uniformly mixed block polymer melt.

[0174] S2. Add the block polymer melt to the forced feeder, adjust the temperature to 185℃, and extrude the strip polymer using a single screw extruder;

[0175] S3. Add the strip polymer to a pelletizer with a rotation frequency of 20.00 Hz to obtain optical conversion masterbatch;

[0176] S4. Mix 3g of light-converting masterbatch, 50g of linear low-density polyethylene and 2g of vinyl bis-stearamide, and add them to the hopper of the blown film machine. The temperature of the material barrel in the three temperature zones of the blown film machine is 130℃, 150℃ and 165℃ respectively, the temperature of the die head is 160℃, the rotation frequency of the screw is 12.00Hz and the winding speed is 160rpm to prepare the light-converting agricultural film.

[0177] Comparative Example 1

[0178] The difference between this comparative example and Example 1 is that the light-converting agent prepared in Example 1 is not added.

[0179] Comparative Example 2

[0180] The difference between this comparative example and Example 1 is that the light-converting agent prepared in Example 1 was replaced with a commercially available light-converting agent purchased from Hubei Xingyan New Material Technology Co., Ltd.

[0181] Comparative Example 3

[0182] The difference between this comparative example and Example 1 is that no modified carbon quantum dot powder was added during the preparation of the light-converting agent in Example 1.

[0183] The light-converting agricultural films prepared in Examples 1-9 and Comparative Examples 1-3 were tested for light transmittance and haze according to the method in GB / T2410-2008.

[0184] Simultaneously, a transmission photometer was used to detect the ultraviolet blocking rate of the light conversion film at a wavelength of 300 nm.

[0185] The tensile properties and tear strength of the light-converting agricultural film were tested using a universal tensile testing machine. The film sample thickness was 0.06 mm, the width was 12 mm, the tensile rate was 50 mm / min, and each sample was tested 5 times and the average value was taken.

[0186] The performance test results are shown in Table 1:

[0187] Table 1

[0188] Test Items Light transmittance (%) Haze (%) UV blocking rate (%) Transverse tensile strength (MPa) Longitudinal tensile strength (MPa) Transverse tear strength (kN / m) Longitudinal tear strength (kN / m) Example 1 83.2 46.12 87.2 36.5 34.2 205 193 Example 2 83.1 46.15 87.5 36.6 34.1 203 192 Example 3 83.3 46.02 87.3 36.3 34.2 202 194 Example 4 82.7 46.07 87.4 35.9 34.3 206 193 Example 5 82.8 45.85 88.1 35.5 34.2 208 195 Example 6 83.5 46.11 88.2 36.2 34.1 206 194 Example 7 83.3 46.13 87.8 36.2 33.8 204 191 Example 8 83.1 46.11 88.2 36.1 33.9 205 192 Example 9 83.5 45.58 87.7 36.3 34.2 204 190 Comparative Example 1 93.6 27.56 58.3 28.9 25.6 156 147 Comparative Example 2 88.5 33.82 69.2 30.5 28.7 178 166 Comparative Example 3 88.6 34.18 68.5 30.8 28.3 181 169

[0189] In summary, the light-converting agricultural films prepared in Examples 1-9, due to the addition of KH550 surface-modified carbon quantum dots (CQDs) as the core and the loading of a stable composite matrix formed by a chitosan-graphene-citric acid crosslinking network, can be used to prepare high-haze, high-scattering functional agricultural films. This is generally advantageous for agricultural applications because diffused light can more evenly illuminate the plant canopy and lower leaves, improving photosynthetic efficiency, while also significantly enhancing the tensile strength, tear strength, and other mechanical properties of the agricultural film.

[0190] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a light-converting agricultural film, characterized in that, Includes the following steps: S1. Add the light-converting agent and matrix to a mixer and mix to obtain a uniformly mixed block polymer melt; S2. Add the block polymer melt to the forced feeder and extrude the polymer into strips using a single screw extruder; S3. Add the strip polymer to the pelletizer to obtain the optical conversion masterbatch; S4. Mix the light-converting masterbatch, matrix and additives, add them to the hopper of the blown film machine, control the temperature of the material cylinder in the three temperature zones of the blown film machine, and prepare the light-converting agricultural film.

2. The method for preparing a light-converting agricultural film according to claim 1, characterized in that, The preparation method of the light-converting agent includes the following steps: S1-1. Add graphene to a 1% chitosan acetic acid solution, adjust the pH, and ultrasonically disperse to form a uniform suspension; S1-2. Add modified carbon quantum dot powder to the suspension and continue sonication to obtain a dispersion; S1-3. Add chitosan powder to the above dispersion, stir magnetically until the powder is completely dissolved, add corn starch and citric acid, and continue stirring for 30-45 minutes to prepare a mixture; S1-4. Add dilute alkali solution dropwise to the above mixture while continuously stirring magnetically to adjust the pH value to 7-9. Pour the adjusted mixture into a horizontal glass plate mold, control the thickness to 0.1-0.2 mm with a scraper, let it stand at room temperature for 1-2 hours, then transfer it to a vacuum drying oven and vacuum dry at 45°C for 4.5 hours. S1-5. After drying, remove the membrane and soak it in deionized water at 25℃ for 1-2 hours, then let it air dry at room temperature for 20-24 hours to obtain the light conversion agent.

3. The method for preparing a light-converting agricultural film according to claim 2, characterized in that, The acetic acid concentration in S1-1 is 1%, and the pH is 3-4.

4. The method for preparing a light-converting agricultural film according to claim 2, characterized in that, In S1-1, ultrasonic dispersion is performed for 30-45 minutes, with an ultrasonic power of 300W and a frequency of 40kHz.

5. The method for preparing a light-converting agricultural film according to claim 2, characterized in that, The magnetic stirring conditions in S1-3 are: 30-40℃ for 1-2 hours, with a rotation speed of 300 r / min.

6. The method for preparing a light-converting agricultural film according to claim 2, characterized in that, The preparation method of the modified carbon quantum dot powder includes the following steps: Citric acid and deionized water were mixed and magnetically stirred until dissolved. The mixture was then transferred to a polytetrafluoroethylene reactor and hydrothermally reacted at 170-190℃ for 3-4 hours. After the reaction, the mixture was allowed to cool naturally to room temperature. The supernatant was collected after centrifugation. Dilute sodium hydroxide solution was added dropwise to the supernatant to adjust the pH to 9-10. KH550 was then added, and the mixture was stirred at 50-60℃ for 1-2 hours. After freeze-drying, modified carbon quantum dot powder was obtained.

7. The method for preparing a light-converting agricultural film according to claim 6, characterized in that, The centrifugation time is 10-15 minutes, and the rotation speed is 8000-8500 r / min.

8. The method for preparing a light-converting agricultural film according to claim 1, characterized in that, The matrix is ​​at least one of low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, high-density polyethylene, polypropylene, and ethylene-vinyl acetate resin.

9. The method for preparing a light-converting agricultural film according to claim 1, characterized in that, The additive is at least one of polyethylene wax, vinyl bis-stearamide, zinc stearate, pentaerythritol stearate, titanate coupling agent, and aluminate coupling agent.

10. A light-converting agricultural film prepared by the preparation method according to any one of claims 1-9.