Multi-layer composite light conversion agricultural seedling greenhouse film

Abstract

The present application relates to the technical field of agricultural seedling greenhouse, and particularly relates to a multi-layer composite light conversion agricultural seedling greenhouse film, which comprises a durable outer layer, an intermediate layer and a functional inner layer in sequence, the durable outer layer comprises 40-50 parts of low-density polyethylene, 40-45 parts of linear low-density polyethylene, 4-6 parts of composite additive and 2-4 parts of PE-g-MAH; the intermediate layer is a light conversion layer; and the functional inner layer comprises 50-70 parts of ethylene-vinyl acetate copolymer (EVA), 25-35 parts of linear low-density polyethylene, 25-35 parts of low-density polyethylene, 15-20 parts of flow agent and 3-5 parts of antifogging agent. The finished agricultural greenhouse plastic film produced by the multi-layer film composite structure, reasonable proportioning and three-layer co-extrusion process has the functions of saving additives, synergistic antifogging and anti-dripping, durability, good transparent performance and mechanical performance, which is very beneficial to the growth and development of crops.

Description

Technical Field

[0001] This invention belongs to the field of agricultural seedling greenhouse technology, specifically relating to a multi-layer composite light-converting agricultural seedling greenhouse film. Background Technology

[0002] Greenhouse seedling cultivation technology is a modern agricultural technology that utilizes facility agriculture (greenhouses, sheds) to control environmental conditions such as temperature, humidity, and light, achieving efficient and intensive seedling cultivation. It is widely used in vegetables, flowers, fruit trees, and cash crops. Agricultural seedling greenhouse film is a high-tech functional agricultural film that optimizes environmental conditions such as light, temperature, and humidity through multi-layer composite processes and light-conversion technology, significantly improving seedling efficiency and crop quality. By adding light-converting agents, ultraviolet (UV) or green light in sunlight is converted into red light (620–720 nm) or blue light (400–500 nm), which is more easily absorbed by plants, promoting photosynthesis. Furthermore, it is designed specifically for the sensitive needs of seedlings for light, temperature, and humidity, providing more precise environmental control than ordinary greenhouse films. However, existing light-converting films have poor durability and short service life. Summary of the Invention

[0003] The purpose of this invention is to provide a multi-layer composite light-converting agricultural seedling greenhouse film to solve the technical problems of poor durability and short service life of existing light-converting films.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] The technical solution provided by this invention is as follows:

[0006] In a first aspect, the present invention provides a multi-layer composite light-converting agricultural seedling greenhouse film, wherein the multi-layer composite light-converting agricultural seedling greenhouse film comprises, in sequence, a durable outer layer, a middle layer, and a functional inner layer; the durable outer layer comprises 40-50 parts of low-density polyethylene, 40-45 parts of linear low-density polyethylene, 4-6 parts of composite additives, and 2-4 parts of PE-g-MAH; the middle layer is a light-converting layer; the functional inner layer comprises 50-70 parts of ethylene-vinyl acetate copolymer (EVA), 25-35 parts of linear low-density polyethylene, 25-35 parts of low-density polyethylene, 15-20 parts of anti-drip agent, and 3-5 parts of anti-fogging agent.

[0007] Preferably, the thickness of the durable outer layer is 15-25 μm; the thickness of the light-converting layer is 30-60 μm; and the thickness of the durable functional inner layer is 15-25 μm.

[0008] Preferably, the light-converting layer is an ethylene vinyl acetate copolymer containing 0.5-1.8% light-converting agent; the light-converting agent includes at least one of stilbene bisbenzoxazole and 5-bis(5-tert-butyl-2-benzoxazole)thiophene.

[0009] Preferably, the VA content in EVA is 5-8%; the dripping agent is KF65020 or KF65015.

[0010] Preferably, the anti-fogging agent is AF-382.

[0011] Preferably, the preparation method of the composite additive includes the following steps:

[0012] S1: Disperse sodium-based montmorillonite powder in water to obtain a montmorillonite suspension. After continuous stirring, the suspension is purified by fractional centrifugation to obtain purified montmorillonite powder.

[0013] In the above process, after centrifugation at 1000-1300 rpm to precipitate larger aggregates, centrifugation at 4000-5000 rpm is used to obtain a second precipitation. Then, centrifugation at 6700-7100 rpm is used to precipitate the remaining small aggregates. Multiple centrifugations are performed to improve size uniformity and yield.

[0014] S2: Add purified montmorillonite powder to water, stir magnetically at room temperature, and then sonicate to obtain montmorillonite dispersion;

[0015] S3: Dissolve hexadecyltrimethylammonium bromide in water at 55-65℃ to obtain a hexadecyltrimethylammonium bromide solution; slowly add the hexadecyltrimethylammonium bromide solution dropwise into a montmorillonite dispersion, stir, centrifuge, wash, dry, and grind through an 80-mesh sieve to obtain hexadecyltrimethylammonium bromide-montmorillonite powder;

[0016] In the above process, the increased interlayer spacing (~2nm) of CTAB-MMT provides growth space for BiOCl nanosheets, preventing aggregation. The hydrophobic surface can be adapted to polymer matrices (such as PE), improving the mechanical properties of the composite material.

[0017] S4: Dissolve Bi(NO3)3·5H2O in HNO3 and stir until transparent to obtain solution A; dissolve NaCl in water to obtain solution B; add hexadecyltrimethylammonium bromide-montmorillonite powder to solution A, disperse by ultrasonication, slowly add solution B dropwise, stir magnetically, heat and react, cool naturally to room temperature, centrifuge to collect the precipitate, wash and dry to obtain composite additive.

[0018] During the above process, BiOCl is generated in situ on montmorillonite.

[0019] Preferably, in step S1, the concentration of the montmorillonite suspension is 2% (w / v); and the stirring time is 36-54 h.

[0020] Preferably, in step S1, the fractional centrifugation purification method is as follows: first, the montmorillonite suspension is centrifuged at 1000-1300 rpm for 10-20 min, then the first supernatant is collected and centrifuged again at 4000-5000 rpm for 8-12 min to obtain a first precipitate and a second supernatant. NaCl is added to the second supernatant to 20 mmol / L to aggregate the nano-sized particles. After centrifugation at 6700-7100 rpm for 8-12 min, the second precipitate is collected. The first and second precipitates are washed with 45%-75% ethanol until no white precipitate is detected in the silver nitrate test filtrate. The first and second precipitates are then combined, freeze-dried for 2-4 days, and then passed through an 80-mesh sieve.

[0021] Preferably, in step S2, the ratio of purified montmorillonite powder to water is 20-40g:2-4L; the magnetic stirring time is 20-28h; and the ultrasonic treatment conditions are: ultrasonic power of 350-450W and ultrasonic treatment time of 15-25min.

[0022] Preferably, in step S3, the ratio of hexadecyltrimethylammonium bromide to water is 8.8-17.6 g: 1-2 L; the pH adjustment method is to adjust the pH to 8-9 with 0.1 mol / L NaOH; the stirring conditions are: stirring temperature of 55-65℃ and stirring time of 5-7 h.

[0023] Preferably, in step S4, the concentration of HNO3 is 0.1 mol / L; the ratio of Bi(NO3)3·5H2O, HNO3, NaCl, water, and hexadecyltrimethylammonium bromide-montmorillonite powder is 19.4-40 g: 400-800 mL: 2.9-6 g: 400-800 mL: 7-14 g; the ultrasonic dispersion method is: ultrasonic dispersion at a power of 150-250 W for 4-6 min; the magnetic stirring time is 25-35 min; the heating conditions are: heating rate of 2-4℃ / min, heating temperature of 175-185℃; the reaction time is 10-14 h; the centrifugation speed is 6500-7000 rpm; the washing method is: washing with ethanol and water alternately 3-5 times; the drying conditions are: drying temperature of 55-65℃, drying time of 10-14 h.

[0024] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0025] 1. This invention expands the interlayer spacing of montmorillonite using hexadecyltrimethylammonium bromide, providing growth space for BiOCl nanosheets, avoiding aggregation, and facilitating the insertion of polyethylene molecular chains to form intercalation structures, thus improving compatibility and dispersibility. Simultaneously, the hydrophobic surface adapts to the polymer matrix, reducing interfacial energy and inhibiting phase separation. The silicate layers of montmorillonite form a nanocomposite structure within a linear low-density polyethylene molecular matrix. Hexadecyltrimethylammonium bromide treatment entangles the alkyl chains of montmorillonite with the linear low-density polyethylene molecular chains, reducing stress concentration. All components synergistically enhance the mechanical properties of the composite material.

[0026] 2. In this invention, montmorillonite nanosheets have a wide surface size of several hundred nanometers, exhibiting strong ultraviolet absorption and scattering capabilities. BiOCl degrades ultraviolet light through light absorption, forming a dual protection mechanism that significantly enhances the film's UV resistance without affecting light transmittance. This invention employs multi-layer composite technology, adding composite additives to the outermost layer to enhance the durability and mechanical properties of the greenhouse film. Light conversion technology transforms green light into red or blue light, which is more easily absorbed by plants, promoting photosynthesis. The functional inner layer ensures light transmission and prevents condensation inside the film, reducing disease. PE-g-MAH enhances interfacial adhesion, preventing delamination. The scientifically formulated and three-layer co-extrusion process produces a finished agricultural greenhouse plastic film that saves on additives, provides synergistic anti-drip and anti-fogging properties, longevity, transparency, and good mechanical properties, making it highly beneficial for crop growth and development. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a mechanical property diagram of the multi-layer composite light-converting agricultural seedling greenhouse film of the present invention;

[0029] Figure 2 This is an optical performance diagram of the multi-layer composite light-converting agricultural seedling greenhouse film of the present invention. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0031] Example 1

[0032] This embodiment discloses a method for preparing a composite additive, including the following steps:

[0033] S1: Disperse sodium-based montmorillonite powder in water to obtain a 2% (w / v) montmorillonite suspension. After stirring continuously for 48 hours, the suspension is purified by fractional centrifugation to obtain purified montmorillonite powder.

[0034] The fractional centrifugation purification method is as follows: First, the montmorillonite suspension is centrifuged at 1200 rpm for 15 min, and the first supernatant is collected. Then, it is centrifuged at 4500 rpm for 10 min to obtain a first precipitate and a second supernatant. NaCl is added to the second supernatant to 20 mmol / L to aggregate the nano-sized particles. After centrifugation at 6900 rpm for 10 min, the second precipitate is collected. The first and second precipitates are washed with 60% ethanol until no white precipitate is detected in the filtrate by silver nitrate test. The first and second precipitates are then combined, freeze-dried for 3 days, and then passed through an 80-mesh sieve.

[0035] S2: Add 30g of purified montmorillonite powder to 3L of water, stir magnetically at room temperature for 24h, and then sonicate at 400W for 20min to obtain montmorillonite dispersion.

[0036] S3: At 60℃, 13g of hexadecyltrimethylammonium bromide was dissolved in 1.5L of water and stirred until transparent to obtain a hexadecyltrimethylammonium bromide solution; the hexadecyltrimethylammonium bromide solution was slowly added dropwise to a montmorillonite dispersion, the pH was adjusted to 8.5 with 0.1mol / L NaOH, and the mixture was stirred at 60℃ for 6 hours. After stirring, the mixture was centrifuged, washed, dried, and ground through an 80-mesh sieve to obtain hexadecyltrimethylammonium bromide-montmorillonite powder.

[0037] S4: Dissolve 30g Bi(NO3)3·5H2O in 600mL of 0.1mol / L HNO3 and stir until transparent to obtain solution A; dissolve 4.5g NaCl in 600mL of deionized water to obtain solution B; add 10.5g hexadecyltrimethylammonium bromide-montmorillonite powder to solution A, ultrasonically disperse at 200W for 56min, then slowly add solution B, magnetically stir for 30min, then heat to 180℃ at a heating rate of 3℃ / min, react for 12h, and after naturally cooling to room temperature, collect the precipitate at 6800rpm, wash with ethanol and water alternately 4 times, and dry at 60℃ for 12h to obtain the composite additive.

[0038] Example 2

[0039] This embodiment discloses a multi-layer composite light-converting agricultural seedling greenhouse film, which comprises a durable outer layer, a middle layer, and a functional inner layer. The durable outer layer comprises 45 parts of low-density polyethylene, 43 parts of linear low-density polyethylene, 5 parts of the composite additive prepared in Example 1, and 3 parts of PE-g-MAH. The middle layer is a light-converting layer. The functional inner layer comprises 60 parts of ethylene-vinyl acetate copolymer (EVA), 30 parts of linear low-density polyethylene, 30 parts of low-density polyethylene, 18 parts of KF65020, and 4 parts of AF-382.

[0040] The light-converting layer is an ethylene-vinyl acetate copolymer containing 1% light-converting agent; the light-converting agent is stilbene bisbenzoxazole.

[0041] Prepare the raw materials according to the requirements of the raw material preparation process before plastic film blow molding. With three extrusion heads, an imported or domestic wide-width (9 meters or more) three-layer co-extrusion blow molding unit can be used to form the film in one step and achieve the effect of three-layer co-extrusion.

[0042] Example 3

[0043] This embodiment discloses a multi-layer composite light-converting agricultural seedling greenhouse film, which comprises a durable outer layer, a middle layer, and a functional inner layer. The durable outer layer comprises 40-50 parts of low-density polyethylene, 40 parts of linear low-density polyethylene, 6 parts of the composite additive prepared in Example 1, and 2 parts of PE-g-MAH. The middle layer is a light-converting layer. The functional inner layer comprises 70 parts of ethylene-vinyl acetate copolymer (EVA), 25 parts of linear low-density polyethylene, 35 parts of low-density polyethylene, 15 parts of KF65015, and 5 parts of AF-382.

[0044] The light-converting layer is an ethylene-vinyl acetate copolymer containing 0.5% light-converting agent; the light-converting agent is 5-bis(5-tert-butyl-2-benzoxazolyl)thiophene.

[0045] Prepare the raw materials according to the requirements of the raw material preparation process before plastic film blow molding. With three extrusion heads, an imported or domestic wide-width (9 meters or more) three-layer co-extrusion blow molding unit can be used to form the film in one step and achieve the effect of three-layer co-extrusion.

[0046] Example 4

[0047] This embodiment discloses a multi-layer composite light-converting agricultural seedling greenhouse film, which comprises a durable outer layer, a middle layer, and a functional inner layer. The durable outer layer comprises 40-50 parts of low-density polyethylene, 45 parts of linear low-density polyethylene, 4 parts of the composite additive prepared in Example 1, and 4 parts of PE-g-MAH. The middle layer is a light-converting layer. The functional inner layer comprises 50 parts of ethylene-vinyl acetate copolymer (EVA), 35 parts of linear low-density polyethylene, 25 parts of low-density polyethylene, 20 parts of KF65020, and 3 parts of AF-382.

[0048] The light-converting layer is an ethylene vinyl acetate copolymer containing 1.8% light-converting agent; the light-converting agent is stilbene bisbenzoxazole.

[0049] Prepare the raw materials according to the requirements of the raw material preparation process before plastic film blow molding. With three extrusion heads, an imported or domestic wide-width (9 meters or more) three-layer co-extrusion blow molding unit can be used to form the film in one step and achieve the effect of three-layer co-extrusion.

[0050] Comparative Example 1

[0051] Compared with Example 1, the durable outer layer of the multi-layer composite light-converting agricultural seedling greenhouse film of Comparative Example 1 did not have composite additives added, while other conditions remained unchanged.

[0052] Experimental Example

[0053] The performance of the multilayer composite light-converting agricultural seedling greenhouse film of Examples 2-4 and Comparative Example 1 was tested, and the test results are as follows: Figure 1 , Figure 2 As shown:

[0054] Light transmittance was measured using a photometer; tensile testing was performed according to ASTM D882-02 standard.

[0055] Light transmittance was measured using a UV-Vis spectrometer (UV-1900); UV blocking rate was tested according to ISO 4892.

[0056] according to Figure 1 , Figure 2 As shown in Examples 2-4 and Comparative Example 1, the multi-layer composite light-converting agricultural seedling greenhouse film prepared by this invention has good mechanical properties, light transmittance, and durability. The comparison between Comparative Example 1 and Examples 2-4 shows that adding composite additives can improve the performance of the multi-layer composite light-converting agricultural seedling greenhouse film.

[0057] 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.

[0058] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A multi-layer composite light-converting agricultural seedling greenhouse film, characterized in that, The multi-layer composite light-converting agricultural seedling greenhouse film comprises, in sequence, a durable outer layer, a middle layer, and a functional inner layer. The durable outer layer comprises 40-50 parts of low-density polyethylene, 40-45 parts of linear low-density polyethylene, 4-6 parts of composite additives, and 2-4 parts of PE-g-MAH. The middle layer is a light-converting layer. The functional inner layer comprises 50-70 parts of ethylene-vinyl acetate copolymer (EVA), 25-35 parts of linear low-density polyethylene, 25-35 parts of low-density polyethylene, 15-20 parts of anti-drip agent, and 3-5 parts of anti-fogging agent. The preparation method of the composite additive includes the following steps: S1: Disperse sodium-based montmorillonite powder in water to obtain a montmorillonite suspension. After continuous stirring, the suspension is purified by fractional centrifugation to obtain purified montmorillonite powder. S2: Add purified montmorillonite powder to water, stir magnetically at room temperature, and then sonicate to obtain montmorillonite dispersion; S3: Dissolve hexadecyltrimethylammonium bromide in water at 55-65℃ to obtain a hexadecyltrimethylammonium bromide solution; slowly add the hexadecyltrimethylammonium bromide solution dropwise into a montmorillonite dispersion, stir, centrifuge, wash, dry, and grind through an 80-mesh sieve to obtain hexadecyltrimethylammonium bromide-montmorillonite powder; S4: Dissolve Bi(NO3)3·5H2O in HNO3 and stir until transparent to obtain solution A; dissolve NaCl in water to obtain solution B; add hexadecyltrimethylammonium bromide-montmorillonite powder to solution A, disperse by ultrasonication, slowly add solution B dropwise, stir magnetically, heat and react, cool naturally to room temperature, centrifuge to collect the precipitate, wash and dry to obtain composite additive.

2. The multi-layer composite light-converting agricultural seedling greenhouse film according to claim 1, characterized in that, The thickness of the durable outer layer is 15-25 μm; the thickness of the light-converting layer is 30-60 μm; and the thickness of the durable functional inner layer is 15-25 μm.

3. The multi-layer composite light-converting agricultural seedling greenhouse film according to claim 1, characterized in that, The light-converting layer is an ethylene-vinyl acetate copolymer (EVA) containing 0.5-1.8% light-converting agent; the light-converting agent includes at least one of stilbene bisbenzoxazole and 5-bis(5-tert-butyl-2-benzoxazole)thiophene.

4. The multi-layer composite light-converting agricultural seedling greenhouse film according to claim 1, characterized in that, The EVA contains 5-8% VA.

5. The multi-layer composite light-converting agricultural seedling greenhouse film according to claim 1, characterized in that, In step S1, the concentration of the montmorillonite suspension is 2 g / 100 mL; the stirring time is 36-54 h.

6. The multi-layer composite light-converting agricultural seedling greenhouse film according to claim 1, characterized in that, In step S1, the fractional centrifugation purification method is as follows: First, the montmorillonite suspension is centrifuged at 1000-1300 rpm for 10-20 min. Then, the first supernatant is collected and centrifuged again at 4000-5000 rpm for 8-12 min to obtain a first precipitate and a second supernatant. NaCl is added to the second supernatant to 20 mmol / L to aggregate the nano-sized particles. After centrifugation at 6700-7100 rpm for 8-12 min, the second precipitate is collected. The first and second precipitates are washed with 45%-75% ethanol until no white precipitate is detected in the silver nitrate test filtrate. The first and second precipitates are then combined, freeze-dried for 2-4 days, and then passed through an 80-mesh sieve.

7. The multi-layer composite light-converting agricultural seedling greenhouse film according to claim 1, characterized in that, In step S2, the ratio of purified montmorillonite powder to water is 20-40g:2-4L; the magnetic stirring time is 20-28h; and the ultrasonic treatment conditions are: ultrasonic power of 350-450W and ultrasonic treatment time of 15-25min.

8. The multi-layer composite light-converting agricultural seedling greenhouse film according to claim 1, characterized in that, In step S3, the ratio of hexadecyltrimethylammonium bromide to water is 8.8-17.6 g: 1-2 L; pH adjustment method: adjust the pH to 8-9 with 0.1 mol / L NaOH; stirring conditions: stirring temperature is 55-65℃, stirring time is 5-7 h.

9. The multi-layer composite light-converting agricultural seedling greenhouse film according to claim 1, characterized in that, In step S4, the concentration of HNO3 is 0.1 mol / L; the ratio of Bi(NO3)3·5H2O, HNO3, NaCl, water, and hexadecyltrimethylammonium bromide-montmorillonite powder is 19.4-40 g: 400-800 mL: 2.9-6 g: 400-800 mL: 7-14 g; the ultrasonic dispersion method is: ultrasonic dispersion at a power of 150-250 W for 4-6 min; the magnetic stirring time is 25-35 min; the heating conditions are: heating rate of 2-4℃ / min, heating temperature of 175-185℃; the reaction time is 10-14 h; the centrifugation speed is 6500-7000 rpm; the washing method is: washing with ethanol and water alternately 3-5 times; the drying conditions are: drying temperature of 55-65℃, drying time of 10-14 h.

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