Preparation method of long-acting photo-functional inorganic oxide additive for agricultural film

Abstract

The application discloses a preparation method of a long-acting light function inorganic oxide additive for agricultural films. First, inorganic oxide and water are mixed to obtain slurry A; then, a polymethacrylic acid dispersant is added into the slurry A, and the slurry A is ground in a stirring mill to obtain slurry B; then, the dispersant is added into the slurry B, and sand milling is performed until the particle size reaches 100-300 nm to obtain slurry C; then, a silane coupling agent is added into the slurry C, and the slurry C is stirred and reacted in the stirring mill, and then dried to obtain modified powder; finally, the modified powder is mixed with polyethylene, and melt extrusion granulation is performed to obtain the additive. In the method, the polymethacrylic acid dispersant is added first, and then the silane coupling agent is added, so that a physical-chemical hybrid interface layer is constructed on the surface of the inorganic oxide, the particle size of the inorganic oxide is reduced, and the interface bonding force between the inorganic oxide and the polyethylene is enhanced through a covalent bond. The agricultural film prepared by using the modified inorganic oxide additive can maintain the light function characteristics of the inorganic oxide, and the light transmittance of the agricultural film is better than that of the agricultural film prepared by using the unmodified inorganic oxide additive.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of agricultural light functional agricultural films, and relates to a preparation method of a long-acting light functional inorganic oxide additive for agricultural films. BACKGROUND

[0002] Light functional agricultural films are core materials in modern facility agriculture. By adding specific light functional additives, the sunlight spectrum reaching the surface of crops can be regulated, so as to realize precise regulation of the growth environment of crops. At present, light functional additives are mainly divided into the following three categories: pure organic additives, pure inorganic additives, and inorganic-organic mixed additives. Among them, the organic components in pure organic additives and inorganic-organic mixed additives have poor light resistance, heat resistance and stability, and are easily decomposed to cause light functional attenuation, thereby shortening the service life of the agricultural film. In contrast, inorganic oxide light functional additives have the advantages of high stability, strong weather resistance and long fluorescence lifetime, and are an ideal choice for preparing long-life light functional agricultural films.

[0003] However, when the inorganic oxide is melt-blended with polyethylene (PE), the following problems mainly exist: (1) due to the large difference in polarity between the inorganic oxide and the PE, effective chemical bonds or strong physical adsorption cannot be formed between them, resulting in a large number of defects at the interface between the two, so that the stress cannot be effectively transmitted, thereby seriously reducing the mechanical properties of the agricultural film; (2) the inorganic oxide powder is easy to agglomerate in the non-polar PE matrix. The agglomerates not only cause the light functional efficiency to decrease, but also form stress concentration points in the PE matrix, further reducing the mechanical properties of the agricultural film. Therefore, a new inorganic oxide surface modification process needs to be developed to solve the problems of the combination and dispersion of the inorganic oxide and the PE matrix, so as to obtain an inorganic oxide light functional additive which has good combination with the PE and excellent dispersion in the PE matrix without reducing the light efficiency of the inorganic oxide on the premise.

[0004] Based on this, the application is proposed. SUMMARY

[0005] In order to solve the above technical problems, the application aims to provide a preparation method of long-acting light functional inorganic oxide additive for agricultural film, which comprises the following steps: mixing inorganic oxide and water to obtain slurry A; adding polymethacrylic acid dispersant into the slurry A and grinding in a stirring mill to obtain slurry B; adding dispersant into the slurry B and sand grinding until the particle size reaches 100-300 nm to obtain slurry C; adding silane coupling agent into the slurry C, stirring and reacting in the stirring mill, and then drying to obtain modified powder; and mixing the powder with polyethylene, melt extruding and granulating to obtain the additive. The application builds a physical-chemical hybrid interface layer on the surface of the inorganic oxide by adding polymethacrylic acid dispersant first and then adding silane coupling agent, which reduces the particle size and enhances the interfacial bonding force with polyethylene through covalent bond. The agricultural film prepared by using the modified inorganic oxide additive can maintain the light functional characteristics of the inorganic oxide and has better light transmittance than the agricultural film prepared by using unmodified inorganic oxide additive.

[0006] In order to achieve the above-mentioned purposes, the technical scheme adopted by the application is as follows:

[0007] A preparation method of long-acting light functional inorganic oxide additive for agricultural film, which comprises the following steps in sequence:

[0008] S1, adding inorganic oxide and deionized water into a stirring mill to obtain slurry A; adding polymethacrylic acid dispersant into the stirring mill and stirring at 30-50 Hz for 2-4 h to obtain slurry B;

[0009] S2, pouring the slurry B into a high-speed sand mill, adding polymethacrylic acid dispersant in batches at a speed of 1000-1300 rpm, the total mass of the added polymethacrylic acid dispersant being 0.1-5 wt.% of the total mass of the slurry A, until the particle size of the slurry reaches 100-300 nm, to obtain slurry C;

[0010] When adding the polymethacrylic acid dispersant in batches, the polymethacrylic acid dispersant is added every 10-20 min, and the mass of the polymethacrylic acid dispersant added each time is 0.05-2.5 wt.% of the total mass of the slurry A;

[0011] S3, pouring the slurry C into the stirring mill, weighing the silane coupling agent, and adding 0.1-2 wt.% of the total mass of the slurry A every 10-20 min at 10-20 Hz until the addition of the silane coupling agent is completed, then increasing the stirring speed, and after the stirring is completed, placing the slurry in an oven and drying at 80-130℃ until the weight is constant to obtain modified inorganic oxide powder;

[0012] S4. Place the modified inorganic oxide powder and polyethylene powder in a mixer, with the inorganic oxide powder accounting for 10-50 wt.% of the total mass of the mixed powder. Stir for 30-60 min, then pour the mixed powder into a twin-screw granulator. After melt extrusion and granulation, obtain the long-lasting light-functional inorganic oxide additive for agricultural films.

[0013] As a limitation of the present invention, in step S1, the inorganic oxide is one or more of rare earth oxides, transition metal oxides or solid solution oxides.

[0014] The rare earth oxide is one or more of Y2O3, Sm2O3, Eu2O3, La2O3, and Sc2O3;

[0015] The transition metal oxide is one or more of Fe2O3, MnO, and ZnO;

[0016] The solid solution oxide is Y₂O₃:Bi 3+ Eu 3+ YAG, YAG:Eu 3+ One or more of them.

[0017] As another limitation of the present invention, in step S1, the polymethacrylic acid dispersant is one or more of ammonium polymethacrylate, polymethacrylic acid, and DOLAPIX CE 64.

[0018] As a third limitation of the present invention, in step S1, the mass of the inorganic oxide accounts for 30-70 wt.% of the total mass of slurry A.

[0019] As a fourth limitation of the present invention, in step S1, the mass of the polymethacrylic acid dispersant is 0.1-5 wt.% of the total mass of slurry A.

[0020] In this invention, the quality of the added polymethacrylic acid dispersant affects the powder dispersion effect. If too much is added, it will lead to excessive repulsion between particles, affecting the subsequent bonding of the silane coupling agent on the particle surface. If too little is added, it will not be able to cover the surface of the powder particles, resulting in particle agglomeration.

[0021] As a fifth limitation of the present invention, in step S3, the silane coupling agent is one or more of aminopropyltriethoxysilane, epoxysilane, and propyltrimethoxysilane.

[0022] As a sixth limitation of the present invention, in step S3, the mass of the silane coupling agent is 0.5-10 wt.% of the total mass of slurry A.

[0023] In this invention, the amount of silane coupling agent affects the powder dispersibility and the subsequent bonding of modified oxide powder with PE. If the amount of silane coupling agent is too large, it will compete with polymethyl methacrylate dispersants for adsorption sites on the inorganic oxide surface, resulting in decreased dispersion stability and flocculation. If the amount of silane coupling agent is too small, the physical-chemical hybrid interface strength formed with the polymethyl methacrylate dispersant is insufficient, affecting the subsequent bonding of the powder with PE.

[0024] As a seventh limitation of the present invention, in step S3, the speed-up stirring is carried out according to the following procedure: first, the stirring frequency is increased to 30-40 Hz and stirred for 1-2 hours; then the stirring frequency is increased to 40-50 Hz and stirred for 1-2 hours; finally, the stirring frequency is increased to 50-60 Hz and stirred for 1-2 hours until the slurry is in the form of fine foam.

[0025] As an eighth limitation of the present invention, in step S4, during the melt extrusion and granulation, the temperature of the feeding zone of the twin-screw granulator is 130-170°C, the temperature of the melting zone is 150-190°C, and the temperature of the metering zone is 170-200°C.

[0026] In this invention, the polyanionic chains of a polymethacrylic acid dispersant are first physically adsorbed onto the surface of an inorganic oxide through ionic and hydrogen bonds, forming a stable primary polymer dispersion layer. Subsequently, a silane coupling agent is added and hydrolyzes to generate highly reactive silanols (-Si-OH). This hydrolysis product can penetrate the porous primary polymer dispersion layer, undergoing a condensation reaction with free hydroxyl groups on the inorganic oxide surface to form strong Si-OM covalent bonds; and forming hydrogen bonds with the carboxyl / carboxylate groups of the polymethacrylic acid dispersant. Simultaneously, its organic segments are bonded to the polymer backbone of the primary dispersion layer through van der Waals forces and chain entanglement, ultimately forming a unique synergistic adsorption layer on the surface of the inorganic oxide particles. In this structure, the polymethacrylic acid dispersant primarily exhibits steric hindrance, ensuring the dispersion stability of the inorganic oxide particles and providing a platform for subsequent modification; while the silane coupling agent acts as an anchoring molecule, tightly fixing the polymer layer to the oxide substrate through covalent bonds. This combination of physical and chemical action overcomes the instability of simple physical adsorption, resulting in modified inorganic oxides with submicron particle size, excellent powder dispersibility, and no agglomeration.

[0027] During the melt processing of masterbatch preparation, the main and side chains of polymethacrylic acid dispersants have hydrocarbon structures, similar to the molecular chain structure of PE. The molecular chains of both are physically bonded through van der Waals forces and chain entanglement. The "buffer layer" formed by the polymethacrylic acid dispersant transforms the polar interactions on its inner side into compatibility with the non-polar PE on its outer side. The silane coupling agent contains a carbon-carbon double bond (C=C) at its organic end with a methacryloyloxy group. During melt processing, under thermal shear, free radicals generated by the PE molecular chains undergo a free radical grafting reaction with this double bond, thereby establishing a strong covalent bond between the inorganic oxide and the PE matrix. Simultaneously, the long chains of the polymethacrylic acid dispersant and the segments of the silane coupling agent intertwine to form a robust interfacial network. Silane coupling agents anchor PE to this network via covalent bonds, while polymethacrylic acid dispersants, through large-area chain entanglement and van der Waals forces, "pull" and fix a large number of PE molecular chains around this anchoring point, enabling the inorganic oxides to achieve excellent dispersibility and interfacial bonding in PE. This strong interface allows stress to be effectively transferred from the soft PE matrix to the rigid inorganic oxide particles. Agricultural films prepared using modified inorganic oxides exhibit excellent water resistance, heat resistance, and aging resistance.

[0028] The above-mentioned technical solution of the present invention is a whole in which each step is closely related and mutually influential, and together they determine the morphological characteristics and performance of the product.

[0029] The above technical solution has the following advantages or beneficial effects:

[0030] 1. This invention first utilizes a polymethacrylic acid dispersant to establish a uniform "working platform," and then constructs a robust "bridge network" through covalent bonding of silanes. At the molecular level, the two form a physicochemically synergistic hybrid interface layer through hydrogen bonds and chain entanglement, ultimately maximizing the surface modification effect of inorganic oxides. Furthermore, the silane coupling agent anchors PE to this network through covalent bonds, while the polymethacrylic acid dispersant "pulls" and fixes a large number of PE molecular chains around this anchoring point through large-area chain entanglement and van der Waals forces. The modified inorganic oxides are uniformly distributed in the PE matrix, without agglomeration, and exhibit excellent binding properties with PE.

[0031] 2. The addition of polymethacrylic acid dispersants in this invention will not affect the luminescence properties of inorganic oxides, thus preserving their long-lasting and efficient luminescence.

[0032] 3. Compared with the agricultural film prepared by the modified inorganic oxide additives of the present invention, the agricultural film prepared by the modified inorganic oxide additives has significantly improved mechanical properties and light transmittance.

[0033] 4. The preparation method of this invention is simple, the process is easy to control, it is applicable to a variety of inorganic oxides, and it is suitable for large-scale industrial production.

[0034] This invention is applicable to the preparation of long-lasting photofunctional inorganic oxide additives for agricultural films.

[0035] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0036] Figure 1 The following are comparative diagrams showing the sedimentation of the slurries obtained in steps S1-S3 of Comparative Examples 1-4 and Example 4 of the present invention, wherein: (a) is a slurry diagram of Comparative Example 1; (b) is a slurry diagram of Comparative Example 2; (c) is a slurry diagram of Comparative Example 3; (d) is a slurry diagram of Comparative Example 4; and (e) is a slurry diagram of Example 4.

[0037] Figure 2 The following are particle size diagrams of the slurries obtained by Comparative Examples 1-7 and Example 4 after steps S1-S3: (a) is the particle size diagram of Comparative Example 1; (b) is the particle size diagram of Comparative Example 2; (c) is the particle size diagram of Comparative Example 3; (d) is the particle size diagram of Comparative Example 4; (e) is the particle size diagram of Comparative Example 5; (f) is the particle size diagram of Example 4; (g) is the particle size diagram of Comparative Example 6; and (h) is the particle size diagram of Comparative Example 7.

[0038] Figure 3 This is a photograph of the additive masterbatch prepared in Example 4 of the present invention.

[0039] Figure 4 The diagrams show the longitudinal and transverse strengths of the agricultural film made with the additives prepared in Example 4 and Comparative Example 5 of this invention, and the pure PE film.

[0040] Figure 5 Transmittance diagrams of agricultural films made with additives prepared in Examples 4 and 5 of the present invention and pure PE films;

[0041] Figure 6 The modified Y₂O₃:Bi prepared in Example 4 of this invention 3+ Eu 3+ The emission spectra of the powder and the agricultural film obtained using the additives prepared in Example 4, wherein: (a) excitation spectrum; (b) emission spectrum;

[0042] Figure 7 This is a scanning electron microscope image of the modified inorganic oxide powder obtained in steps S1-S3 of Example 4 of the present invention;

[0043] Figure 8This is a scanning electron microscope image of the modified inorganic oxide powder obtained by steps S1-S3 in Comparative Example 5 of the present invention. Detailed Implementation

[0044] The following embodiments are merely some, not all, of the embodiments of the present invention. Therefore, the detailed descriptions of the embodiments provided below are not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0045] In this invention, unless otherwise specified, all equipment and raw materials are commercially available or commonly used in the industry. The polyethylene material used in the embodiments and comparative examples of this invention is PE-L DGH1875 product from Sinopec (Tianjin) Petrochemical Co., Ltd. Unless otherwise specified, the methods in the following embodiments are conventional methods in the art. Example 1

[0046] This embodiment prepares a long-lasting photofunctional inorganic oxide additive for agricultural films. The preparation process and steps are as follows:

[0047] S1. Add 30 kg of Y2O3 powder and 70 kg of deionized water to a stirred mill to obtain slurry A; then add 100 g of DOLAPIX CE 64 to the stirred mill and stir for 4 h at 30 Hz to obtain slurry B. The particle size of the slurry is 500-600 nm.

[0048] S2. Pour slurry B into a high-speed sand mill and add 100 g of DOLAPIX CE 64 at 1000 rpm (the addition should be done in batches, i.e., add 50 g of DOLAPIX CE 64 at the beginning of sand milling, and add the remaining 50 g of DOLAPIX CE 64 after sand milling for 10 minutes). Sand mill for a total of 2 hours until the final sand milled particle size reaches 100-300 nm, and obtain slurry C.

[0049] S3. Pour slurry C into a stirred mill, weigh 1 kg of propyltrimethoxysilane, and add 100 g every 10 min at 10 Hz until the addition is complete. Then increase the stirring frequency to 30 Hz and stir for 1 h, then increase the stirring frequency to 40 Hz and stir for 1 h, and finally increase the stirring frequency to 50 Hz and stir for 1 h until the slurry is in a fine foam state. Then place the slurry in an oven and dry it at 80℃ to constant weight to obtain modified inorganic oxide powder.

[0050] S4. Place the modified inorganic oxide powder and polyethylene powder in a mixer, with the inorganic oxide powder accounting for 50 wt.% of the total mass of the mixed powder. Stir for 30 min, then pour the mixed powder into a twin-screw granulator. After melt extrusion and granulation, the temperature of the extruder feeding zone is 130℃, the temperature of the melting zone is 150℃, and the temperature of the metering zone is 170℃ to obtain a long-lasting light-functional inorganic oxide additive for agricultural films. Example 2

[0051] This embodiment prepares a long-lasting photofunctional inorganic oxide additive for agricultural films. The preparation process and steps are as follows:

[0052] S1, 30 kg of yttrium aluminum garnet (Y3Al5O) 12 YAG powder and 13 kg of deionized water were added to a stirred mill to obtain slurry A; then 860 g of polymethyl methacrylate was added to the stirred mill and stirred for 3 h at 40 Hz to obtain slurry B, with a particle size of 500-600 nm.

[0053] S2. Pour slurry B into a high-speed sand mill and add 1290 g of polymethyl methacrylate at 1100 rpm (the addition should be done in batches, i.e., add 430 g of polymethyl methacrylate at the beginning of sand milling, add another 430 g of polymethyl methacrylate after sand milling for 10 min, and add the remaining 430 g of polymethyl methacrylate after sand milling for another 10 min). Sand mill for a total of 10 hours until the final sand milling particle size reaches 100-300 nm, and obtain slurry C.

[0054] S3. Pour slurry C into a stirred mill, weigh 215 g of aminopropyltriethoxysilane, and add 43 g every 15 min at 15 Hz until the addition is complete. Increase the stirring frequency to 35 Hz and stir for 1.5 h, then increase the stirring frequency to 45 Hz and stir for 1.5 h, and finally increase the stirring frequency to 55 Hz and stir for 1.5 h until the slurry is in a fine foam state. Then place the slurry in an oven and dry it at 100℃ to constant weight to obtain modified inorganic oxide powder.

[0055] S4. Place the modified inorganic oxide powder and polyethylene powder in a mixer, with the inorganic oxide powder accounting for 30 wt.% of the total mass of the mixed powder. Stir for 50 min, then pour the mixed powder into a twin-screw granulator. After melt extrusion and granulation, the temperature of the extruder feeding zone is 150℃, the temperature of the melting zone is 180℃, and the temperature of the metering zone is 190℃ to obtain a long-lasting light-functional inorganic oxide additive for agricultural films. Example 3

[0056] This embodiment prepares a long-lasting photofunctional inorganic oxide additive for agricultural films. The preparation process and steps are as follows:

[0057] S1. Add 30 kg of Fe2O3 powder and 30 kg of deionized water to a stirred mill to obtain slurry A; then add 3 kg of ammonium polymethyl methacrylate to the stirred mill and stir for 2 h at 50 Hz to obtain slurry B. The particle size of the slurry is 500-600 nm.

[0058] S2. Pour slurry B into a high-speed sand mill and add 3 kg of polymethyl methacrylate at 1300 rpm (the addition should be done in batches, i.e., add 1.5 kg of polymethyl methacrylate at the beginning of sand milling, and add the remaining 1.5 kg of polymethyl methacrylate after sand milling for 20 min). Sand mill for a total of 3 h until the final sand milling particle size reaches 100-300 nm, and obtain slurry C.

[0059] S3. Pour slurry C into a stirred mill, weigh 6 kg of aminopropyltriethoxysilane, and add 1.2 kg every 20 min at 20 Hz until the addition is complete. Increase the stirring frequency to 40 Hz and stir for 2 h, then increase the stirring frequency to 50 Hz and stir for 2 h, and finally increase the stirring frequency to 60 Hz and stir for 2 h until the slurry is in a fine foam state. Then place the slurry in an oven and dry it at 130℃ to constant weight to obtain modified inorganic oxide powder.

[0060] S4. Place the modified inorganic oxide powder and polyethylene powder in a mixer, with the inorganic oxide powder accounting for 10 wt.% of the total mass of the mixed powder. Stir for 60 min, then pour the mixed powder into a twin-screw granulator. After melt extrusion and granulation, the temperature of the extruder feeding zone is 170℃, the temperature of the melting zone is 190℃, and the temperature of the metering zone is 200℃ to obtain a long-lasting light-functional inorganic oxide additive for agricultural films. Example 4

[0061] This embodiment prepares a long-lasting light-functional agricultural film additive, and the preparation process and steps are as follows:

[0062] S1, 30 kg of Y2O3:Bi 3+ Eu 3+ The powder and 30 kg of deionized water were added to a stirred mill to obtain slurry A; then 1.8 kg of DOLAPIX CE 64 were added to the stirred mill and stirred for 2 h at 50 Hz to obtain slurry B, with a particle size of 500-600 nm.

[0063] S2. Pour slurry B into a high-speed sand mill and add 3 kg of DOLAPIX CE 64 at 1100 rpm (the addition should be done in batches, i.e., add 1.5 kg of DOLAPIX CE 64 at the beginning of sand milling, and add the remaining 1.5 kg of DOLAPIX CE 64 after sand milling for 15 min). Sand mill for a total of 2 h until the final sand milled particle size reaches 100-300 nm, and obtain slurry C.

[0064] S3. Pour slurry C into a stirred mill, weigh 1.2 kg of propyltrimethoxysilane, and add 0.6 kg every 20 min at 15 Hz until the addition is complete. Increase the stirring frequency to 40 Hz and stir for 1.5 h, then increase the stirring frequency to 50 Hz and stir for 1.5 h, and finally increase the stirring frequency to 60 Hz and stir for 1.5 h until the slurry is in a fine foam state. Then place the slurry in an oven and dry it at 130℃ to constant weight to obtain modified inorganic oxide powder.

[0065] S4. Place the modified inorganic oxide powder and polyethylene powder in a mixer, with the inorganic oxide powder accounting for 10 wt.% of the total mass of the mixed powder. Stir for 30 min, then pour the mixed powder into a twin-screw granulator. After melt extrusion and granulation, the temperature of the extruder feeding zone is 170℃, the temperature of the melting zone is 190℃, and the temperature of the metering zone is 200℃ to obtain a long-lasting light-functional inorganic oxide additive for agricultural films. Comparative Example

[0066] To investigate the influence of reactants on the performance of the product during the preparation process of this invention, the following comparative experiments were conducted. Different long-lasting light-functional agricultural film additives were prepared according to the following comparative examples:

[0067] Comparative Example 1

[0068] This comparative example prepares a long-lasting light-functional inorganic oxide additive for agricultural films. The preparation process is similar to that of Example 4, except that propyltrimethoxysilane is not added in step S3.

[0069] Comparative Example 2

[0070] This comparative example prepares a long-lasting light-functional inorganic oxide additive for agricultural films. The preparation process is similar to that of Example 4, except that DOLAPIX CE 64 is not added in steps S1 and S2.

[0071] Comparative Example 3

[0072] This comparative example prepares a long-lasting photofunctional inorganic oxide additive for agricultural films. The preparation process is similar to that of Example 4, except that DOLAPIX CE 64 and propyltrimethoxysilane are not added sequentially, but rather simultaneously to the slurry. The specific process is as follows:

[0073] S1, Y2O3:Bi 3+ Eu 3+ The powder and deionized water are added to a stirred mill to obtain slurry A, wherein Y2O3:Bi 3+ Eu 3+ The powder accounts for 50 wt.% of the total mass of slurry A; then, DOLAPIX CE 64 and propyltrimethoxysilane are added to the stirred mill, each accounting for 0.5% of the total mass of the slurry. The stirred mill speed is 30 Hz, and the stirring time is 2 hours. The slurry particle size is 500-600 nm, resulting in slurry B.

[0074] S2. Pour slurry B into a high-speed sand mill at 1000 rpm. Weigh DOLAPIX CE 64 and propyltrimethoxysilane, each accounting for 1.5% of the total mass of slurry A. At the beginning of sand milling, add 0.5% DOLAPIX CE 64 and 0.5% propyltrimethoxysilane. After sand milling for 10 min, add another 0.5% DOLAPIX CE 64 and 0.5% propyltrimethoxysilane. Sand mill again for 10 min, then add another 0.5% DOLAPIX CE 64 and 0.5% propyltrimethoxysilane. Sand mill for a total of 2 h until the final particle size reaches 100-300 nm, thus obtaining slurry B.

[0075] S3. Pour slurry B into a mixing mill and stir at a stirring frequency of 30 Hz for 1 h. Then increase the stirring frequency to 40 Hz for 1 h, and finally increase the stirring frequency to 50 Hz for 1 h until the slurry is in the form of fine foam. Then place the slurry in an oven and dry it at 80℃ to obtain modified inorganic oxide powder.

[0076] S4. Place the modified inorganic oxide powder and polyethylene powder in a mixer, with the inorganic oxide powder accounting for 30% of the total mass of the mixed powder. Stir for 30 minutes, then pour the mixed powder into a twin-screw granulator. After melt extrusion and granulation, the temperature of the extruder feeding zone is 130℃, the temperature of the melting zone is 150℃, and the temperature of the metering zone is 170℃, to obtain an additive for long-lasting light-functional agricultural films.

[0077] Comparative Example 4

[0078] This comparative example prepares a long-lasting photofunctional inorganic oxide additive for agricultural films. The preparation process is similar to that of Example 1, except that in steps S1 and S2, DOLAPIX CE 64 is replaced with propyltrimethoxysilane, and in step S3, propyltrimethoxysilane is replaced with DOLAPIX CE 64. That is, when preparing the additive, propyltrimethoxysilane is added first, and then DOLAPIX CE 64 is added.

[0079] Comparative Example 5

[0080] This comparative example prepares a long-lasting photofunctional inorganic oxide additive for agricultural films. The preparation process is similar to that of Example 1, except that DOLAPIX CE 64 and propyltrimethoxysilane are not added during the preparation of the additive.

[0081] Comparative Example 6

[0082] This comparative example prepares a long-lasting light-functional inorganic oxide additive for agricultural films. The preparation process is similar to that of Example 1, except that in steps S1 and S2, DOLAPIX CE 64 is replaced with stearic acid.

[0083] Comparative Example 7

[0084] This comparative example prepares a long-lasting light-functional inorganic oxide additive for agricultural films. The preparation process is similar to that of Example 1, except that in step S3, propyltrimethoxysilane is replaced with phthalate.

[0085] The additives prepared according to the embodiments and comparative examples of the present invention were subjected to a series of tests, as detailed below:

[0086] like Figure 1 The figure shows a comparison of the sedimentation of the slurries obtained in Comparative Examples 1-4 and Example 4 before drying, after steps S1-S3. It can be seen from the figure that the slurry in Comparative Example 1 exhibits significant sedimentation and agglomeration. This is due to the reaction between DOLAPIX CE 64 and Y2O3:Bi. 3+ Eu 3+ The powder undergoes physical adsorption, and its interaction with PE involves van der Waals forces and chain entanglement, both of which are weak interactions. Under external forces, interfacial debonding easily occurs. At higher temperatures, polymer chain segment motion intensifies, and DOLAPIX CE 64 molecules in the Y2O3:Bi... 3+ Eu 3+ The adsorption on the powder surface can become unstable, or even desorb, during the later stages of masterbatch and agricultural film preparation. This can affect the relationship between DOLAPIX CE 64 and Y2O3:Bi. 3+ Eu 3+ The powder adsorption layer will be damaged, leading to filler agglomeration.

[0087] Comparative Example 2 slurry exhibited significant stratification, with a difference in particle size between the upper and lower layers, and varying degrees of agglomeration. This is due to the presence of propyltrimethoxysilane in the Y2O3:Bi... 3+ Eu 3+ During powder modification, due to their small molecular size and slow diffusion, hydrolyzed propyltrimethoxysilane molecules preferentially condense to form useless oligomers instead of being grafted onto the powder surface, making the powder highly prone to agglomeration. Although successfully grafted propyltrimethoxysilane can form covalent bridges between the powder and PE, theoretically achieving the highest bonding strength, the agglomerated Y2O3:Bi molecules already agglomerate during the slurry stage, resulting in... 3+ Eu 3+ The powder has significant stress defects after being compounded with PE, which can lead to a substantial decrease in the mechanical properties of agricultural film.

[0088] Comparative Example 3 slurry also exhibited significant stratification, with a difference in particle size between the upper and lower layers, and varying degrees of agglomeration. This is because when DOLAPIX CE 64 and propyltrimethoxysilane are added simultaneously, they react in the Y2O3:Bi... 3+ Eu 3+ The limited number of active sites on the powder surface compete for adsorption. This competitive adsorption leads to a disordered and non-uniform interfacial layer structure, which easily induces particle flocculation. Even more detrimental is that DOLAPIX CE 64 preferentially adsorbs and encapsulates propyltrimethoxysilane, or its carboxylate groups interact with the silanols produced by silane hydrolysis, both of which weaken the effective function of the adsorption. Ultimately, the resulting interfacial layer exhibits weak bonding and numerous structural defects.

[0089] The slurry in Comparative Example 4 exhibited significant sedimentation and agglomeration. This was because the lack of steric hindrance from DOLAPIX CE 64 made it highly susceptible to self-condensation reactions, resulting in cotton-like precipitates. The subsequently added DOLAPIX CE 64 molecules could not find sufficient suitable adsorption sites, leaving the slurry in a metastable state with high viscosity and a tendency to settle.

[0090] Example 4 shows that the slurry is uniformly dispersed without obvious stratification or sedimentation, indicating that adding DOLAPIX CE 64 first and then propyltrimethoxysilane is the most beneficial approach. First, a uniform "working platform" is established using a polymethacrylic acid dispersant, and then a robust "bridge network" is constructed through covalent bonding with a silane coupling agent. At the molecular level, these two components form a physicochemically synergistic hybrid interface layer through hydrogen bonds and chain entanglement, ultimately maximizing the surface modification effect of the oxide.

[0091] like Figure 2The figures show the particle size distribution of the slurries obtained in Comparative Examples 1-7 and Example 4 after steps S1-S3. It can be seen from the figures that the particle size distribution of Comparative Example 1, which only added DOLAPIX CE 64 slurry, is significantly smaller. 50 The particle size was 0.358 μm. Comparative Example 2 only had D particles with added propyltrimethoxysilane slurry. 50 The particle size was 0.704 μm. Comparative Example 3 showed the addition of both DOLAPIX CE 64 and propyltrimethoxysilane slurry. 50 The particle size was 1.809 μm. Comparative Example 4 showed the addition of propyltrimethoxysilane followed by DOLAPIX CE 64 slurry. 50 The particle size was 2.836 μm. Comparative Example 5, without the addition of propyltrimethoxysilane, showed D... 50 With a particle size of 4.965 μm, in Comparative Example 6, after replacing the polymethacrylate dispersant with stearic acid dispersant, the D of the slurry... 50 The particle size was 3.291 μm. In Comparative Example 7, after replacing the silane coupling agent with titanate, the slurry's D... 50 Particle size is 1.979 μm; D of the slurry in Example 4 50 The particle size is 0.290 μm, indicating that adding DOLAPIX CE 64 first and then propyltrimethoxysilane can achieve uniform dispersion and reduce particle size. Replacing polymethacrylate dispersants with other dispersants or silane coupling agents with other coupling agents cannot achieve the goal of reducing particle size.

[0092] like Figure 3 The figure shows the additive masterbatch prepared in Example 4 of this invention. As can be seen from the figure, the surface of the additive masterbatch is smooth and free of particles, indicating that the modified Y2O3:Bi 3+ Eu 3+ The powder is evenly distributed in PE, without agglomeration, and has excellent binding properties with PE.

[0093] The additives prepared in Example 4 and Comparative Example 5 of this invention were simultaneously extruded and laminated together using a double-layer co-extrusion device through a precision die to produce an agricultural film with long-lasting light-reflecting properties. A series of tests were then conducted on the agricultural film, as detailed below:

[0094] like Figure 4Figure 1 shows the longitudinal and transverse strength of agricultural films made with the additives obtained in Example 4 and Comparative Example 5, as well as pure PE agricultural films. As can be seen from the figure, the transverse and longitudinal strength of the agricultural film made with the additives prepared in Example 4 decreased by approximately 1.5% compared to pure PE agricultural films, while the transverse and longitudinal strength of the agricultural film made with the additives prepared in Comparative Example 5 decreased by approximately 20.6%. This indicates that the modified inorganic oxide powder additives have uniform dispersion in PE and excellent binding properties with PE, significantly reducing the stress concentration phenomenon caused by the direct addition of inorganic oxides.

[0095] like Figure 5 Figure 1 shows the light transmittance of agricultural films prepared with the additives obtained in Example 4 and Comparative Example 5, as well as pure PE agricultural films. As can be seen from the figure, the light transmittance of the agricultural film prepared with the additives obtained in Example 4 is reduced by approximately 3% compared to pure PE agricultural films, while the light transmittance of the agricultural film prepared with the additives obtained in Comparative Example 5 is reduced by approximately 17.6%. This indicates that the modified inorganic oxide powder has a small particle size, uniform dispersion in PE, and no agglomeration.

[0096] like Figure 6 The modified Y2O3:Bi prepared in Example 4 of this invention 3+ Eu 3+ The luminescence spectra of the powder and the agricultural film obtained using the additive prepared in Example 4 are shown in the figure. It can be seen from the figure that the agricultural film prepared using the additive in Example 4 has excellent light conversion effect and retains Y2O3:Bi. 3+ Eu 3+ The light conversion properties of powders.

[0097] like Figure 7 The image shows a scanning electron microscope (SEM) image of the modified inorganic oxide powder obtained in steps S1-S3 of Example 4 of the present invention. As can be seen from the image, the inorganic oxide powder prepared by the method of the present invention has a grain size in the nanometer range, a relatively regular grain morphology, and no agglomeration.

[0098] like Figure 8 The image shows a scanning electron microscope (SEM) image of the modified inorganic oxide powder obtained by steps S1-S3 in Comparative Example 5 of this invention. As can be seen from the image, the nano-sized powder exhibits severe agglomeration, and the grains are difficult to disperse and open, resulting in a large particle size.

[0099] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a long-lasting photofunctional inorganic oxide additive for agricultural films, characterized in that, Follow these steps in sequence: S1. Add inorganic oxide and deionized water to a stirred mill to obtain slurry A; then add polymethacrylic acid dispersant to the stirred mill, wherein the mass of the polymethacrylic acid dispersant is 0.1-5 wt.% of the total mass of slurry A, and stir at 30-50 Hz for 2-4 h to obtain slurry B. S2. Pour the above slurry B into a high-speed sand mill, and add polymethyl methacrylate dispersant in batches at a speed of 1000-1300 rpm. The total mass of the added polymethyl methacrylate dispersant is 0.1-5 wt.% of the total mass of slurry A. Sand mill until the slurry particle size is 100-300 nm to obtain slurry C. S3. Pour slurry C into a stirred mill, weigh the silane coupling agent, and add 0.1-2 wt.% of the total mass of slurry A every 10-20 min at 10-20 Hz until the silane coupling agent is completely added. Then, increase the stirring speed and place the slurry in an oven to dry at 80-130 ℃ to constant weight to obtain modified inorganic oxide powder. S4. Place the modified inorganic oxide powder and polyethylene powder in a mixer, with the inorganic oxide powder accounting for 10-50 wt.% of the total mass of the mixed powder. Stir for 30-60 min, then pour the mixed powder into a twin-screw granulator. After melt extrusion and granulation, obtain the long-lasting light-functional inorganic oxide additive for agricultural films.

2. The preparation method of a long-lasting photofunctional inorganic oxide additive for agricultural films according to claim 1, characterized in that, In step S1, the inorganic oxide is one or more of rare earth oxides, transition metal oxides, or solid solution oxides. The rare earth oxide is one or more of Y2O3, Sm2O3, Eu2O3, La2O3, and Sc2O3; The transition metal oxide is one or more of Fe2O3, MnO, and ZnO; The solid solution oxide is Y₂O₃:Bi 3+ Eu 3+ YAG, YAG:Eu 3+ One or more of them.

3. The method for preparing a long-lasting photofunctional inorganic oxide additive for agricultural films according to claim 1, characterized in that, In step S1, the polymethacrylic acid dispersant is one or more of ammonium polymethacrylate, polymethacrylic acid, and DOLAPIX CE 64.

4. The preparation method of a long-lasting photofunctional inorganic oxide additive for agricultural films according to claim 1, characterized in that, In step S1, the inorganic oxide accounts for 30-70 wt.% of the total mass of slurry A.

5. The preparation method of a long-lasting photofunctional inorganic oxide additive for agricultural films according to claim 1, characterized in that, In step S3, the silane coupling agent is one or more of aminopropyltriethoxysilane, epoxysilane, and propyltrimethoxysilane.

6. The preparation method of a long-lasting photofunctional inorganic oxide additive for agricultural films according to claim 1, characterized in that, In step S3, the mass of the silane coupling agent is 0.5-10 wt.% of the total mass of slurry A.

7. The preparation method of a long-lasting photofunctional inorganic oxide additive for agricultural films according to claim 1, characterized in that, In step S3, the speed-up stirring process is carried out according to the following procedure: first, the stirring frequency is increased to 30-40 Hz and stirred for 1-2 hours; then the stirring frequency is increased to 40-50 Hz and stirred for 1-2 hours; finally, the stirring frequency is increased to 50-60 Hz and stirred for 1-2 hours until the slurry is in the form of fine foam.

8. The method for preparing a long-lasting photofunctional inorganic oxide additive for agricultural films according to claim 1, characterized in that, In step S4, during melt extrusion and granulation, the temperature of the feeding zone of the twin-screw granulator is 130-170℃, the temperature of the melting zone is 150-190℃, and the temperature of the metering zone is 170-200℃.

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