A benzotriazole derivative grafted nanoparticle additive, a preparation method thereof and a polyethylene composite material

Abstract

The application relates to the technical field of polyethylene, and particularly discloses a benzotriazole derivative grafted nanoparticle additive, a preparation method thereof and a polyethylene composite material. The method comprises the following steps: preparing inorganic nanoparticles modified by a silane coupling agent; sequentially performing end group epoxidation and hydroxyl protection on a benzotriazole derivative to obtain a hydroxyl-protected epoxy benzotriazole derivative; and finally, reacting the inorganic nanoparticles modified by the silane coupling agent with the hydroxyl-protected epoxy benzotriazole derivative to obtain the benzotriazole derivative grafted nanoparticle additive. The additive can effectively solve the problem that the nanoparticles are prone to agglomeration in a polyethylene matrix, thereby causing high film haze; when the additive is used for preparing the polyethylene composite material, the haze can be greatly reduced while maintaining high light transmittance, and the tensile strength and processing stability of the material can be improved. The application has controllable process and low cost, is suitable for the production of polyethylene products such as high-transparency packaging films, and has wide application prospect.

Description

Technical Field

[0001] This invention belongs to the field of polyethylene technology, specifically, it relates to a benzotriazole derivative grafted nanoparticle additive, its preparation method, and a polyethylene composite material. Background Technology

[0002] Transparent polyethylene nanocomposites maintain the high light transmittance of the substrate while introducing nanoparticles. , Fillers such as ZnO or layered silicates impart excellent barrier, UV resistance, anti-fogging, and toughening properties to the film. It has been applied in batches to high-transparency vacuum food bags, heat-shrinkable express films, greenhouse long-life films, antistatic protective films for liquid crystal displays, and moisture-proof packaging for flexible OLEDs. In the field of new energy, this material has been developed as an inner layer film for photovoltaic backsheets and an outer layer for lithium battery aluminum-plastic films due to its low haze and high dielectric strength. It can improve the weather resistance of modules and the energy density of batteries, and is expected to replace traditional fluorine films to achieve cost reduction and efficiency improvement.

[0003] However, nanoparticles have significant compatibility differences with polyethylene, and during melt blending, they easily form micron-sized aggregates, leading to a sharp increase in film haze and a decrease in optical properties. Furthermore, nanoparticles are prone to migration and precipitation during high-temperature extrusion, causing die accumulation and poor stability in continuous production. The lack of online rapid monitoring methods for dispersion uniformity makes the preparation of highly transparent, low-haze, and stable polyethylene nanocomposites a persistent challenge for the industry.

[0004] Chinese patent application number 202510688436.2 discloses a method for preparing high-transparency polyethylene film additives by melt grafting nano-silica, which is doubly grafted with quaternary ammonium salt and nucleating agent, onto low-density polyethylene, and then compounding it with antioxidants, antistatic agents, etc. However, this type of additive involves multiple grafting steps, high reaction temperatures, and large solvent consumption, and batch stability and cost control still need to be improved during large-scale production.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] This invention aims to solve the problems of poor compatibility between nanoparticles and polyethylene matrix, easy agglomeration leading to high film haze and deterioration of optical properties in the prior art. It provides a benzotriazole derivative grafted nanoparticle additive prepared by a specific chemical grafting method. This additive can significantly improve the transparency of polyethylene film and reduce its haze, while improving the mechanical properties and processing stability of the material.

[0007] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows: In a first aspect, the present invention provides a method for preparing a benzotriazole derivative-grafted nanoparticle additive, comprising the following steps: (1) Preparation of inorganic nanoparticles modified with silane coupling agent; (2) The benzotriazole derivative was subjected to terminal epoxidation and hydroxyl protection treatment in sequence to obtain hydroxyl-protected epoxy benzotriazole derivative; (3) The inorganic nanoparticles modified by the silane coupling agent are reacted with the hydroxyl-protected epoxy benzotriazole derivative to obtain the benzotriazole derivative grafted nanoparticle additive.

[0008] The preparation method provided by the present invention involves grafting benzotriazole derivatives that have undergone end-group epoxidation and hydroxyl protection onto the surface of inorganic nanoparticles modified with silane coupling agents to obtain high-density covalently grafted benzotriazole derivative-grafted nanoparticle additives. Using this type of nanoparticle additive to fill a modified polyethylene matrix can significantly improve the nucleation efficiency of the composite and also significantly increase the transparency of the composite film.

[0009] In the above technical solution, in step (1), the silane coupling agent is a silane coupling agent with an amino functional group in its molecular structure; amino functional groups It can undergo an efficient and selective "epoxy-amine" ring-opening chemical reaction with the epoxy groups in the benzotriazole derivatives with epoxy groups at the end prepared in step (2), thereby firmly grafting the benzotriazole derivatives onto the surface of nanoparticles in the form of covalent bonds.

[0010] Preferably, the silane coupling agent is selected from at least one of (3-aminopropyl)trimethoxysilane, (3-aminopropyl)triethoxysilane, and 3-[2-(2-aminoethylamino)ethylamino]propyl-trimethoxysilane; (3-Aminopropyl)trimethoxysilane and (3-aminopropyl)triethoxysilane have methoxy / ethoxy groups at one end of their molecules that, upon hydrolysis, can stably bond to the hydroxyl groups on the surface of nanoparticles. The other end has a single primary amino group. These silane coupling agents exhibit high reactivity and low steric hindrance, which facilitates efficient reactions with epoxy groups. 3-[2-(2-aminoethylamino)ethylamino]propyl-trimethoxysilane is a polyamino silane containing three amino groups (one primary and two secondary) in its molecular chain. The longer molecular chain and more amino sites may lead to greater grafting flexibility or density, providing more possibilities for controlling the grafting behavior of the final product. All three silane coupling agents can effectively achieve surface amination of nanoparticles under mild and controllable reaction conditions.

[0011] Preferably, in step (1), the inorganic nanoparticles are silicon dioxide nanoparticles; This invention uses silica nanoparticles, which have extremely high transparency and no absorption in the visible light region. Adding them to a polyethylene matrix will not introduce additional color or affect the light transmittance of the matrix itself. Their refractive index is close to that of polyethylene, which can effectively reduce interfacial light scattering. This has advantages in achieving the core goal of high transparency and low haze.

[0012] After adding silicon dioxide to polyethylene, if nano-sized Small particle size (≤30 nm) and uniform dispersion after surface modification can act as a heterogeneous nucleating agent to refine grains, reduce light scattering, and slightly improve the transparency of the film. However, once the particles agglomerate or the amount added exceeds 2 wt%, the micron-sized aggregates become a large number of scattering centers, the haze increases sharply, the transmittance decreases, "whitening" and crystal points appear on the film surface, and the optical performance deteriorates significantly.

[0013] In order to improve polyethylene / Regarding the transparency of nanocomposites, this invention employs a "grafting to" method. By using a silane coupling agent to chemically modify the surface of inorganic nanoparticles, a benzotriazole derivative that has undergone end-group epoxidation and hydroxyl protection is grafted onto the surface of the inorganic nanoparticles. After using these nanoparticles to fill a modified polyethylene matrix, the nucleation efficiency of the composite can be significantly improved, and the transparency of the composite film is thus significantly increased.

[0014] In the above schemes, when silica is modified by amination using silane coupling agents, the oxygen on the exposed silanol groups on the nanoparticle surface undergoes nucleophilic substitution of the silicon on the silane coupling agent, removing one portion of methanol, and thus the silane coupling agent is bonded to the particle surface through the formation of Si-O-Si bonds. Multiple concerted reactions can occur simultaneously in the above system; therefore, the above reaction process is not the only way for silane coupling agents to bond to the particle surface.

[0015] Preferably, the particle size of the silica nanoparticles is 15~500 nm; more preferably 50~100 nm. This invention limits the particle size of silica nanoparticles to 15~500 nm to avoid excessive particle size leading to increased film haze; it also ensures that the silica nanoparticles have a sufficiently large specific surface area to achieve high grafting density while avoiding uncontrollable agglomeration caused by excessively small particle size.

[0016] The nano-silica particles used in this invention are commercially available or spherical nano-silica synthesized using the sol-gel method. After amination modification of the nano-silica raw material, its particle size remains essentially unchanged.

[0017] Preferably, in step (1), the mass ratio of the inorganic nanoparticles to the silane coupling agent is (2~1): (1~6); more preferably, it is 1: (1~2).

[0018] This invention limits the mass ratio of inorganic nanoparticles to silane coupling agent to (2~1):(1~6) to ensure the formation of high-density, monolayer-covered amino functional groups on the surface of nanoparticles. If the proportion of nanoparticles is too high, insufficient amount of coupling agent will result in incomplete coverage of surface active sites, reducing the subsequent grafting density. If the proportion of coupling agent is too high, excess reagent is prone to self-aggregation to form multilayer adsorption or aggregates, which not only hinders the grafting reaction and affects dispersibility, but also wastes raw materials.

[0019] In the above technical solution, step (1) includes: dispersing inorganic nanoparticles in a first organic solvent, then adding a silane coupling agent to react and obtain silane coupling agent modified inorganic nanoparticles. Preferably, the first organic solvent is selected from at least one of toluene and xylene; Preferably, in step (1), the inorganic nanoparticles are dispersed in a first organic solvent after ultrasonic treatment; Preferably, in step (1), the ultrasonic treatment time is 0.1~2h; In step (1), the physical aggregation of nanoparticles can be completely broken by using the cavitation effect through ultrasonic treatment, so that they can reach a monodisperse state in the organic solvent, providing sufficient contact area for the silane coupling agent and achieving more uniform surface modification.

[0020] Preferably, in step (1), the reaction temperature is 100~120℃ and the reaction time is 12~24h. This ensures that the silane coupling agent is fully hydrolyzed and completely condenses with the hydroxyl groups on the nanoparticle surface to form stable covalent bonds, thereby constructing a complete and high-density amino active layer on the nanoparticle surface. This gentle and continuous thermal process helps improve the conversion rate and uniformity of the modification reaction.

[0021] Preferably, in step (1), the reaction is carried out under the protection of an inert gas (such as nitrogen). An inert gas effectively isolates the silane coupling agent from moisture and oxygen in the air, preventing self-polymerization of the silane coupling agent or oxidation and deactivation of the amino functional groups in the early stages of the reaction, thus ensuring the directional progress of the modification reaction and the stability of the final product. Step (1) ensures that the surface of the nanoparticles acquires high-density, highly reactive amino functional groups, laying a reliable structural foundation for the subsequent efficient grafting with benzotriazole derivatives.

[0022] Preferably, in step (1), after the reaction is completed, the inorganic nanoparticles modified with the silane coupling agent are obtained by centrifugation and washing.

[0023] In the above technical solution, in step (2), the benzotriazole derivative is a benzotriazole derivative containing an epoxidizable unsaturated bond; this unsaturated bond (such as a carbon-carbon double bond) can specifically react with the first modifier (epoxidizing agent) and be converted into a highly reactive epoxy group. This epoxy group can undergo an "epoxide-amine" ring-opening reaction with the amino groups on the surface of the silane coupling agent-modified nanoparticles to achieve covalent, high-density grafting of the benzotriazole derivative.

[0024] Preferably, the benzotriazole derivative is selected from at least one of 2-(2H-benzotriazole-2-yl)-4-methyl-6-(2-methyl-2-propenyl)phenol, 2-allyl-6-(2H-benzo[d][1,2,3]triazole-2-yl)-4-methylphenol, 2-[3-(2H-benzotriazole-2-yl)-4-hydroxyphenyl]ethyl methacrylate and 1-[(1-vinyl)-3-butenyl]-1H-benzotriazole; in the above technical solution, in step (2), the end-group epoxidation treatment includes: reacting the benzotriazole derivative with a first modifier in a second organic solvent to obtain a benzotriazole derivative with an epoxy group at the end group; Preferably, the first modifier is selected from at least one of m-chloroperoxybenzoic acid, peroxybenzoic acid, and dimethyldioxane; Preferably, the molar ratio of the benzotriazole derivative to the first modifier is 1:(1.0-1.2); Preferably, the second organic solvent is selected from at least one of xylene and dichloromethane; Preferably, in the end-group epoxidation treatment, the reaction temperature is 20-30℃ and the reaction time is 10-15 hours; Preferably, the end-group epoxidation treatment is carried out under inert gas protection; this effectively isolates oxygen and moisture in the air, preventing the epoxidizing agent from decomposing and becoming ineffective due to moisture absorption or oxidation, while avoiding side reactions such as hydrolysis and ring opening of newly generated epoxy groups under the action of moisture or oxygen, thereby ensuring that the epoxidation reaction is completed efficiently and specifically.

[0025] Preferably, in the terminal epoxidation treatment, after the reaction is completed, a benzotriazole derivative with an epoxy group at the end is obtained by separation and purification; preferably, the separation and purification is performed by column chromatography.

[0026] In the above technical solution, step (2) includes: reacting the benzotriazole derivative treated with end-group epoxidation with a second modifier in a third organic solvent to obtain a hydroxyl-protected epoxy benzotriazole derivative. The phenolic hydroxyl groups in benzotriazole derivative molecules are reactive under alkaline or high-temperature conditions. If not protected, they will compete with the amino groups on the surface of nanoparticles for epoxide groups, or trigger other side reactions, resulting in low grafting efficiency and uneven products.

[0027] Preferably, the second modifier is selected from at least one of tert-butyldimethylchlorosilane, trimethylsilyl, and triethylsilyl; This invention uses tert-butyldimethylchlorosilane (TBDMSCl) to protect the phenolic hydroxyl group. By forming a stable silane-ether bond, the hydroxyl group is temporarily shielded, preventing side reactions during subsequent high-temperature, alkaline grafting reactions and ensuring the high efficiency and specificity of the grafting reaction. This protecting group is stable under grafting conditions and can be removed under mild conditions after the reaction to restore the hydroxyl group. This invention aims to significantly accelerate the rate and yield of this silanization protection reaction.

[0028] In a preferred embodiment of the hydroxyl protection step of the present invention, the reaction system is further modified by adding the acid-binding agent triethylamine and the nucleophilic catalyst 4-dimethylaminopyridine (DMAP). Wherein: Triethylamine, as an organic base, can promptly neutralize the hydrogen chloride generated from the reaction of tert-butyldimethylchlorosilane with the phenolic hydroxyl group in the hydroxyl protection reaction, thus preventing the ring-opening side reaction of the epoxy groups at the end of the benzotriazole derivative due to the acidic environment and ensuring the integrity of the active sites for subsequent grafting with aminated nanoparticles. 4-Dimethylaminopyridine, as a highly efficient nucleophilic catalyst, can significantly accelerate the rate and conversion of silylation protection reaction, enabling the reaction to be completed in a short time under mild conditions at room temperature. This minimizes the side reactions of epoxy groups, improves the selectivity and purity of hydroxyl protection, and ultimately increases the grafting density of benzotriazole derivatives on the surface of nanoparticles.

[0029] It should be noted that the structures of terminal epoxidation and hydroxyl-protected benzotriazole derivatives can both be prepared using the preparation method provided by this invention under the conditions of selecting the above-mentioned different modifiers.

[0030] Preferably, the third organic solvent is selected from at least one of xylene and dichloromethane; Preferably, in the hydroxyl protection treatment, the reaction temperature is 20-30°C and the reaction time is 10-15 hours; Preferably, the hydroxyl protection treatment is carried out under an inert gas atmosphere; the inert gas (such as nitrogen) can effectively isolate moisture in the air, prevent TBDMSCl from decomposing and becoming ineffective when it comes into contact with water, and ensure that the phenolic hydroxyl protection reaction is completed efficiently; at the same time, this environment can also prevent the hydrogen chloride generated in the reaction from forming an acidic atmosphere in the humid air, thereby preventing side reactions such as ring opening of the acid-sensitive epoxy groups.

[0031] Preferably, in the hydroxyl protection treatment, after the reaction is completed, the hydroxyl-protected epoxybenzotriazole derivative is obtained by separation and purification; preferably, the separation and purification is performed by column chromatography.

[0032] In the above technical solution, in step (3), the mass ratio of the hydroxyl-protected epoxy benzotriazole derivative to the silane coupling agent modified inorganic nanoparticles is (0.3~1.0):0.25; In the above technical solution, step (3) includes: dispersing the silane coupling agent modified inorganic nanoparticles in a fourth organic solvent, and then adding the hydroxyl-protected epoxy benzotriazole derivative to react and obtain the benzotriazole derivative grafted nanoparticle additive. Preferably, the fourth organic solvent is selected from at least one of toluene and xylene; Preferably, the reaction temperature is 100-120℃ and the reaction time is 10-15 hours.

[0033] Preferably, in step (3), the reaction is carried out under the protection of an inert gas; the inert gas (such as nitrogen) can effectively isolate oxygen, avoid the amino group from being oxidized and deactivated, and ensure that it undergoes a highly efficient and specific "epoxy-amine" ring-opening grafting reaction with the epoxy group; at the same time, isolating moisture can prevent the moisture-sensitive epoxy group from undergoing hydrolysis and ring-opening, thereby ensuring a high conversion rate and high grafting density of the grafting reaction, and finally obtaining an additive with stable structure and excellent performance.

[0034] Preferably, in step (3), after the reaction is completed, the benzotriazole derivative grafted nanoparticle additive is obtained by centrifugation, washing and drying.

[0035] In the preparation method provided by this invention, step (1) introduces amino active sites on the surface of inorganic nanoparticles using a silane coupling agent, laying the foundation for subsequent grafting; step (2) converts the unsaturated bonds at the end of the benzotriazole derivative into highly reactive epoxy groups through end-group epoxidation and hydroxyl protection, constructing a molecular bridge for the grafting reaction; and temporarily shields the phenolic hydroxyl groups in the benzotriazole molecule to prevent them from generating side reactions or steric hindrance in subsequent reactions, ensuring the efficiency and specificity of the grafting reaction; finally, step (3) covalently anchors the modified benzotriazole derivative on the surface of the aminated nanoparticles through an "epoxy-amine" ring-opening chemical reaction, forming an additive with a stable structure and controllable grafting density. This invention fundamentally solves the problem of nanoparticle aggregation in polyethylene matrix through the synergistic pathway of surface activation, molecular modification, and grafting. The nanoparticles are not easily migrated or aggregated in polyethylene matrix, and can maintain dispersion even with fluctuations in processing temperature and time, achieving uniform dispersion and significant improvement in optical properties.

[0036] Secondly, this invention provides a benzotriazole derivative-grafted nanoparticle additive prepared by the above method. This additive uses inorganic nanoparticles as the core carrier, and through an epoxy-amine ring-opening covalent reaction, firmly grafts functional segments of the benzotriazole derivative onto the particle surface. This additive possesses both the reinforcing properties of inorganic nanoparticles and the ultraviolet absorption function of the benzotriazole derivative. Simultaneously, through the interfacial regulation effect of the organic segments, it can fundamentally improve the compatibility between the nanoparticles and the polyethylene matrix.

[0037] Preferably, the grafting density of the benzotriazole derivative in the benzotriazole derivative-grafted nanoparticle additive is 3.6~9.0 chains / nm².

[0038] If the grafting density is too low, the benzotriazole derivative segments on the surface of the nanoparticles are not sufficiently covered, failing to form an effective steric hindrance layer and interfacial compatibility layer. This results in the van der Waals forces between nanoparticles not being effectively counteracted, leading to easy aggregation within the polyethylene matrix and the formation of micron-sized aggregates. These aggregates become light scattering centers, causing increased haze and decreased transmittance in the polyethylene composite, resulting in poor optical performance optimization. Simultaneously, insufficient interfacial interaction also affects the reinforcing effect of nanoparticles on polyethylene, leading to minimal improvement in mechanical properties.

[0039] Excessive grafting density may reduce the dispersion efficiency of additives in organic solvents or polyethylene melts, leading to agglomeration. Furthermore, excessive grafting density requires more benzotriazole derivatives and reaction reagents, significantly increasing preparation costs. Simultaneously, excessive organic segments may affect the processing flowability of the polyethylene matrix, adversely impacting subsequent molding processes such as blown film and cast film production.

[0040] Therefore, by controlling the grafting density within the reasonable range defined by this invention, the optimal balance between performance and cost can be achieved. Organic molecules can effectively prevent nanoparticle aggregation and generate good interfacial interactions with polyethylene molecular chains, thereby simultaneously achieving a synergistic improvement in optical performance, mechanical performance, and processing stability.

[0041] Thirdly, the present invention provides a polyethylene composite material, the polyethylene composite material comprising polyethylene and benzotriazole derivative grafted nanoparticle additives. The polyethylene composite material uses polyethylene as the matrix and benzotriazole derivative-grafted nanoparticle additives as functional components. The two form a tight interface between the benzotriazole organic segments grafted on the surface of the additives and the polyethylene molecular chains. The organic segments have good compatibility with the polyethylene molecular chains, which can reduce interfacial tension. They can also prevent the aggregation between nanoparticles through steric hindrance. At the same time, the stable structure of covalent grafting avoids the migration and precipitation of the additives in the matrix. This fundamentally solves the chain problem of poor compatibility, agglomeration and performance degradation in traditional nanoparticle-filled polyethylene materials.

[0042] The polyethylene composite material provided by this invention has multiple performance advantages: on the one hand, the uniformly dispersed nanoparticles can act as heterogeneous nucleating agents to refine polyethylene spherulites, reduce light scattering, and achieve optimized optical performance with high transmittance and low haze; on the other hand, the reinforcing properties of inorganic nanoparticles and the interfacial bridging effect of organic segments work synergistically to increase the tensile strength of the composite material by 10-15% compared with pure polyethylene; at the same time, the ultraviolet absorption function of benzotriazole derivatives endows the composite material with excellent weather resistance, further expanding its application scenarios.

[0043] Preferably, the benzotriazole derivative-grafted nanoparticle additive in the polyethylene composite material has a mass fraction of 0.1 wt% to 1.0 wt%. When the amount of benzotriazole derivative grafted nanoparticle additive is too low, the heterogeneous nucleation effect and interface regulation effect of the additive are not obvious, and the optical properties of the composite material cannot be effectively improved; when the amount is too high, the nanoparticles are prone to local aggregation, which leads to an increase in the haze of the composite material and a decrease in its mechanical properties.

[0044] Preferably, the polyethylene composite material is prepared by dispersing polyethylene and the benzotriazole derivative grafted nanoparticle additive in an organic solvent and then evaporating the organic solvent to obtain the polyethylene composite material. Preferably, the organic solvent is toluene or xylene. These two solvents have good solubility in polyethylene and good compatibility with additives, which can ensure the uniformity of the blend system.

[0045] Preferably, the blending temperature is 90~130℃ and the blending time is 10~24h. These conditions ensure that the polyethylene is fully melted and blended, while avoiding damage to the additive structure due to high temperature.

[0046] Preferably, the organic solvent is evaporated at 100~130℃ to obtain the polyethylene composite material; this temperature range can quickly remove the solvent while ensuring the structural stability of the composite material after molding.

[0047] Preferably, the polyethylene composite material is a polyethylene film; Preferably, the light transmittance of the polyethylene film is >85%; Preferably, the haze of the polyethylene film is <60%; More preferably, the haze of the polyethylene film is <40%.

[0048] The polyethylene composite material is a polyethylene film with a light transmittance >85% and a haze <60% (preferably, haze <40%), which can meet the application requirements of high-transparency packaging, new energy films, and other fields. Furthermore, this composite material can be processed into various forms of products such as sheets, pipes, and injection molded parts through different processes such as blown film, casting, and extrusion, expanding the application scenarios of polyethylene materials.

[0049] By adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art.

[0050] 1. This invention utilizes a "grafting to" method to covalently anchor benzotriazole UV-absorbing units onto the surface of nanoparticles at a high density, employing an epoxy-amine ring-opening reaction. This successfully prepares modified nanoparticles with controllable grafting density. The grafting density can be precisely controlled by adjusting the feed ratio of nanoparticles to benzotriazole derivatives during the reaction, thus adapting to different application requirements. The grafting density range is 3.6~9.0 chains / nm².

[0051] 2. The preparation method provided by this invention effectively solves the industry problem of easy agglomeration of nanoparticles in a polyethylene matrix. The organic molecular chains introduced through chemical grafting greatly improve the compatibility between nanoparticles and polyethylene, enabling them to be uniformly dispersed during melt blending and avoiding the formation of micron-sized agglomerates. The polyethylene film prepared using the additives of this invention exhibits significantly reduced haze (as low as 38.8%) while maintaining high light transmittance (up to 88.8%), resulting in a fundamental improvement in optical performance.

[0052] 3. The additive provided by this invention not only improves the optical properties of composite materials but also comprehensively enhances their mechanical properties and processing adaptability. The modified nanoparticles act as highly efficient heterogeneous nucleating agents, refining polyethylene spherulites and reducing interfacial light scattering. Their uniform dispersion in the matrix increases the tensile strength of the composite material by 10-15% with minimal impact on the polymer's melt flowability. This means the additive can be directly used in existing blown film or cast film production lines without equipment modification, exhibiting excellent process compatibility and industrialization prospects. Simultaneously, the covalent bonding method avoids the migration and precipitation of small molecule additives, improving product lifespan and production stability.

[0053] In summary, this invention achieves high transparency and low haze while also possessing advantages such as controllable preparation methods, stable product performance, and low production costs, thus having broad prospects for widespread application. Detailed Implementation

[0054] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0055] It should be noted that the structure of the hydroxyl-protected epoxybenzotriazole derivative in the following embodiments of the present invention is as follows: However, the following embodiments are only preferred embodiments of the present invention, used to illustrate the present invention but not to limit the scope of the present invention. It is understood that benzotriazole derivatives with other functional groups can also be selected.

[0056] In all the following embodiments, unless otherwise specified, "room temperature" refers to an ambient temperature of 20-25°C.

[0057] In all the following embodiments, the specific conditions for separation and purification by column chromatography in step S3 are as follows: wet loading, with an eluent ratio of ethyl acetate to petroleum ether of 2:1.

[0058] In all the following embodiments, the specific conditions for separation and purification by column chromatography in step S4 are as follows: wet loading, with a developing solvent ratio of dichloromethane:petroleum ether = 2:1.

[0059] Detection method: 1. Grafting density: The grafting density of benzotriazole derivatives in benzotriazole derivative-grafted nanoparticle additives, as determined by TGA testing, is calculated using the following formula:

[0060] in, G γ Grafting rate; G d Grafting density; The difference between the thermal weight loss of the benzotriazole derivative-grafted nanoparticle additive and the thermal weight loss of the nanoparticles. is the specific surface area of ​​the nanoparticles; The molecular weight is that of the benzotriazole derivative. is Avogadro's constant.

[0061] The TGA test conditions were as follows: the test was conducted on a PE-TGA8000 instrument, with a sample mass of 2-3 mg. The temperature was increased from 30°C to 100°C at a rate of 40°C / min, held at a constant temperature for 2 min, and then increased from 100°C to 800°C at a rate of 20°C / min.

[0062] Specific surface area of ​​nanoparticles Test method: ρ is the particle density, and d is the particle radius. 2. Transmittance (%): The transmittance was determined by spectrophotometry according to GB / T 2410-2008, with a sample thickness of 0.2 mm.

[0063] 3. Haze (%): Determined by haze meter method according to GB / T 2410-2008, with a sample thickness of 0.2 mm.

[0064] 4. Tensile strength: The tensile strength of the sample was tested using a universal tensile testing machine in accordance with GB / T 1040.1-2025. The sample width was 3 mm, and the tensile rate was 20 mm / min.

[0065] 5. Melt flowability: Refer to GB / T 3682.1-2018, the melt flow rate MI is determined by a melt indexer: MI = m * 600 / t, where m is the mass of melt flowing out per unit time t.

[0066] The drugs used in the following examples and their sources are shown in the table below:

[0067] Note: In all the experimental examples and comparative examples below, the polyethylene used was LD605 low-density polyethylene (LDPE) produced by Beijing Yanshan Petrochemical Co., Ltd. of China Petrochemical Corporation, with a melt index of 7.53 g / 10min (test conditions: 190℃ / 2.16kg) and a density of 0.92 g / cm³.

[0068] The present invention will be further described in detail below with reference to specific embodiments: Example 1

[0069] The specific steps for preparing benzotriazole derivative-grafted nanoparticle additives are as follows: S1: Add 2 g of silica nanoparticles with a particle size of 50 nm to 100 ml of xylene, and sonicate for 30 min to disperse the nanoparticles evenly in xylene to obtain a silica nanoparticle dispersion. S2: 1.2 ml of (3-aminopropyl)trimethoxysilane coupling agent was added to the silica nanoparticle dispersion. The entire reaction system was heated at 115 °C for 12 h under nitrogen protection. The product obtained after the reaction was completed was centrifuged, and the lower precipitate was washed once with ethanol and twice with xylene before being dispersed in xylene to obtain silane coupling agent modified inorganic nanoparticles.

[0070] S3: 2-Allyl-6-(2H-benzo[d][1,2,3]triazol-2-yl)-4-methylphenol and m-chloroperoxybenzoic acid (m-CPBA) were added to 50 ml of dichloromethane at a mass ratio of 1:3. After reacting at room temperature under nitrogen protection for 12 h, the epoxy benzotriazole derivative was obtained by column chromatography. S4: Epoxybenzotriazole derivative, tert-butyldimethylchlorosilane, triethylamine and 4-dimethylaminopyridine were added to 80 ml of dichloromethane in a mass ratio of 5:8:6:4. After reacting at room temperature under nitrogen protection for 12 h, the hydroxyl-protected epoxybenzotriazole derivative was obtained by column chromatography. S5: Silica nanoparticles modified with (3-aminopropyl)trimethoxysilane coupling agent were added to 60 ml of xylene and sonicated for 30 min to ensure uniform dispersion. Then, a hydroxyl-protected epoxybenzotriazole derivative was added at a mass ratio of 2:1 to the nanoparticles. The reaction was carried out at 110 °C for 12 h under nitrogen protection. The product was centrifuged at 12000 rpm for 15 min, washed once with ethanol, and twice with xylene before being dispersed in xylene. A grafting density of 4.2 chains / nm was obtained. 2 Benzotriazole derivative grafted silica nanoparticles. Example 2

[0071] The specific steps for preparing benzotriazole derivative-grafted nanoparticle additives are as follows: S1: Add 2g of silica nanoparticles with a particle size of 50 nm to 100 ml of xylene, and sonicate for 30 min to disperse the nanoparticles evenly in xylene to obtain a silica nanoparticle dispersion. S2: Add 1.2 ml of (3-aminopropyl)trimethoxysilane coupling agent to the silica nanoparticle dispersion. The entire reaction system is heated at 115 °C for 12 h under nitrogen protection. After the reaction is complete, the product is centrifuged, the lower precipitate is washed once with ethanol, washed twice with xylene, and then dispersed in xylene.

[0072] S3: 2-Allyl-6-(2H-benzo[d][1,2,3]triazol-2-yl)-4-methylphenol and m-chloroperoxybenzoic acid (m-CPBA) were added to 50 ml of dichloromethane at a mass ratio of 1:3. After reacting at room temperature under nitrogen protection for 12 h, the epoxy benzotriazole derivative was obtained by column chromatography. S4: Epoxybenzotriazole derivative, tert-butyldimethylchlorosilane, triethylamine and 4-dimethylaminopyridine were added to 80 ml of dichloromethane in a mass ratio of 5:8:6:4. After reacting at room temperature under nitrogen protection for 12 h, the hydroxyl-protected epoxybenzotriazole derivative was obtained by column chromatography. S5: Silica nanoparticles modified with (3-aminopropyl)trimethoxysilane coupling agent were added to 60 ml of xylene and sonicated for 30 min to ensure uniform dispersion. Then, a hydroxyl-protected epoxybenzotriazole derivative was added at a mass ratio of 4:1 to the nanoparticles. The reaction was carried out at 110 °C for 12 h under nitrogen protection. The product was centrifuged at 12000 rpm for 15 min, washed once with ethanol, and twice with xylene before being dispersed in xylene. A grafting density of 9 chains / nm was obtained. 2 Benzotriazole derivative grafted silica nanoparticles. Example 3

[0073] The specific steps for preparing benzotriazole derivative-grafted nanoparticle additives are as follows: S1: Add 2 g of silica nanoparticles with a particle size of 100 nm to 100 ml of xylene, and sonicate for 30 min to disperse the nanoparticles evenly in xylene to obtain a silica nanoparticle dispersion. S2: Add 1.2 ml of (3-aminopropyl)trimethoxysilane coupling agent to the silica nanoparticle dispersion. The entire reaction system is heated at 115 °C for 12 h under nitrogen protection. After the reaction is complete, the product is centrifuged, the lower precipitate is washed once with ethanol, washed twice with xylene, and then dispersed in xylene.

[0074] S3: 2-Allyl-6-(2H-benzo[d][1,2,3]triazol-2-yl)-4-methylphenol and m-chloroperoxybenzoic acid (m-CPBA) were added to 50 ml of dichloromethane at a mass ratio of 1:3. After reacting at room temperature under nitrogen protection for 12 h, the epoxy benzotriazole derivative was obtained by column chromatography. S4: Epoxybenzotriazole derivative, tert-butyldimethylchlorosilane, triethylamine and 4-dimethylaminopyridine were added to 80 ml of dichloromethane in a mass ratio of 5:8:6:4. After reacting at room temperature under nitrogen protection for 12 h, the hydroxyl-protected epoxybenzotriazole derivative was obtained by column chromatography. S5: Silica nanoparticles modified with (3-aminopropyl)trimethoxysilane coupling agent were added to 60 ml of xylene and sonicated for 30 min to ensure uniform dispersion. Then, a hydroxyl-protected epoxybenzotriazole derivative was added at a mass ratio of 6:5 to the nanoparticles. The reaction was carried out at 110 °C for 12 h under nitrogen protection. The product was centrifuged at 12000 rpm for 15 min, washed once with ethanol, and twice with xylene before being dispersed in xylene. A grafting density of 3.58 chains / nm was obtained. 2 Benzotriazole derivative grafted silica nanoparticles. Example 4

[0075] The specific steps for preparing benzotriazole derivative-grafted nanoparticle additives are as follows: S1: Add 2 g of silica nanoparticles with a particle size of 100 nm to 100 ml of xylene, and sonicate for 30 min to disperse the nanoparticles evenly in xylene to obtain a silica nanoparticle dispersion. S2: Add 1.2 ml of (3-aminopropyl)trimethoxysilane coupling agent to the silica nanoparticle dispersion. The entire reaction system is heated at 115 °C for 12 h under nitrogen protection. After the reaction is complete, the product is centrifuged, the lower precipitate is washed once with ethanol, washed twice with xylene, and then dispersed in xylene.

[0076] S3: 2-Allyl-6-(2H-benzo[d][1,2,3]triazol-2-yl)-4-methylphenol and m-chloroperoxybenzoic acid (m-CPBA) were added to 50 ml of dichloromethane at a mass ratio of 1:3. After reacting at room temperature under nitrogen protection for 12 h, the epoxy benzotriazole derivative was obtained by column chromatography. S4: Epoxybenzotriazole derivative, tert-butyldimethylchlorosilane, triethylamine and 4-dimethylaminopyridine were added to 80 ml of dichloromethane in a mass ratio of 5:8:6:4. After reacting at room temperature under nitrogen protection for 12 h, the hydroxyl-protected epoxybenzotriazole derivative was obtained by column chromatography. S5: Silica nanoparticles modified with (3-aminopropyl)trimethoxysilane coupling agent were added to 60 ml of xylene and sonicated for 30 min to ensure uniform dispersion. Then, a hydroxyl-protected epoxybenzotriazole derivative was added at a mass ratio of 2.4:1 to the nanoparticles. The reaction was carried out at 110 °C for 12 h under nitrogen protection. The product was centrifuged at 12000 rpm for 15 min, washed once with ethanol, and twice with xylene before being dispersed in xylene. A grafting density of 6.54 chains / nm was obtained. 2 Benzotriazole derivative grafted silica nanoparticles.

[0077] The grafting details of the benzotriazole derivative-grafted nanoparticle additives prepared in Examples 1-4 are shown in Table 2.

[0078]

[0079] The following experimental examples further illustrate the application of the benzotriazole derivative-grafted nanoparticle additive prepared according to the present invention in a polyethylene matrix. However, the embodiments provided herein are merely preferred embodiments of the present invention, and the scope of the present invention is not limited thereto.

[0080] Experimental Example 1 The benzotriazole derivative-grafted silica nanoparticles prepared in Example 1 were added to the polyethylene matrix at a ratio of 0.1 wt%. The specific steps were as follows: 0.1 wt% benzotriazole derivative-grafted silica nanoparticles were added to 40 ml xylene and dispersed for 30 min. The mixture was stirred at room temperature for 6 h to obtain a nanoparticle dispersion. 99.9 wt% polyethylene was added to 40 ml xylene and magnetically stirred at 100 °C for 6 h. The nanoparticle dispersion was then added to a polyethylene xylene solution and mixed at 100 °C for 10 h. The reaction solution was poured into a petri dish and placed on a hot plate at 130 °C to completely evaporate the solvent. A polyethylene composite material with a thickness of 0.2 mm was obtained by hot pressing.

[0081] Experiment Example 2 The benzotriazole derivative-grafted silica nanoparticles prepared in Example 1 were added to the polyethylene matrix at a ratio of 0.5 wt%. The specific steps were as follows: 0.5 wt% benzotriazole derivative-grafted silica nanoparticles were added to 40 ml xylene and dispersed for 30 min. The mixture was stirred at room temperature for 6 h to obtain a nanoparticle dispersion. 99.5 wt% polyethylene was added to 40 ml xylene and magnetically stirred at 100 ℃ for 6 h. The nanoparticle dispersion was added to a polyethylene xylene solution and mixed at 100 ℃ for 10 h. The reaction solution was poured into a petri dish and placed on a hot plate at 130 ℃ to completely evaporate the solvent. A polyethylene composite material with a thickness of 0.2 mm was obtained by hot pressing.

[0082] Experimental Example 3 The benzotriazole derivative-grafted silica nanoparticles prepared in Example 1 were added to the polyethylene matrix at a ratio of 1 wt%. The specific steps were as follows: 1 wt% benzotriazole derivative-grafted silica nanoparticles were added to 40 ml xylene and dispersed for 30 min. The mixture was stirred at room temperature for 6 h to obtain a nanoparticle dispersion. 99 wt% polyethylene was added to 40 ml xylene and magnetically stirred at 100 °C for 6 h. The nanoparticle dispersion was added to a polyethylene xylene solution and mixed at 100 °C for 10 h. The reaction solution was poured into a petri dish and placed on a hot plate at 130 °C to completely evaporate the solvent. A polyethylene composite material with a thickness of 0.2 mm was obtained by hot pressing.

[0083] Experiment Example 4 The benzotriazole derivative-grafted silica nanoparticles prepared in Example 2 were added to the polyethylene matrix at a ratio of 0.1 wt%. The specific steps were as follows: 0.1 wt% benzotriazole derivative-grafted silica nanoparticles were added to 40 ml xylene and dispersed for 30 min. The mixture was stirred at room temperature for 6 h to obtain a nanoparticle dispersion. 99.9 wt% polyethylene was added to 40 ml xylene and magnetically stirred at 100 ℃ for 6 h. The nanoparticle dispersion was added to a polyethylene xylene solution and mixed at 100 ℃ for 10 h. The reaction solution was poured into a petri dish and placed on a hot plate at 130 ℃ to completely evaporate the solvent. A polyethylene composite material with a thickness of 0.2 mm was obtained by hot pressing.

[0084] Experimental Example 5 The benzotriazole derivative-grafted silica nanoparticles obtained in Example 2 were added to the polyethylene matrix at a ratio of 0.5 wt%. The specific steps were as follows: 0.5 wt% benzotriazole derivative-grafted silica nanoparticles were added to 40 ml xylene and dispersed for 30 min. The mixture was stirred at room temperature for 6 h to obtain a nanoparticle dispersion. 99.5 wt% polyethylene was added to 40 ml xylene and magnetically stirred at 100 ℃ for 6 h. The nanoparticle dispersion was added to a polyethylene xylene solution and mixed at 100 ℃ for 10 h. The reaction solution was poured into a petri dish and placed on a hot plate at 130 ℃ to completely evaporate the solvent. A polyethylene composite material with a thickness of 0.2 mm was obtained by hot pressing.

[0085] Experimental Example 6 The benzotriazole derivative-grafted silica nanoparticles prepared in Example 2 were added to the polyethylene matrix at a ratio of 1 wt%. The specific steps were as follows: 1 wt% of benzotriazole derivative-grafted silica nanoparticles were added to 40 ml of xylene and dispersed for 30 min. The mixture was stirred at room temperature for 6 h to obtain a nanoparticle dispersion. 99 wt% of polyethylene was added to 40 ml of xylene and magnetically stirred at 100 ℃ for 6 h. The nanoparticle dispersion was added to a polyethylene xylene solution and mixed at 100 ℃ for 10 h. The reaction solution was poured into a petri dish and placed on a hot plate at 130 ℃ to completely evaporate the solvent. A polyethylene composite material with a thickness of 0.2 mm was obtained by hot pressing.

[0086] Experimental Example 7 The benzotriazole derivative-grafted silica nanoparticles prepared in Example 3 were added to the polyethylene matrix at a ratio of 0.1 wt%. The specific steps were as follows: 0.1 wt% benzotriazole derivative-grafted silica nanoparticles were added to 40 ml xylene and dispersed for 30 min. The mixture was stirred at room temperature for 6 h to obtain a nanoparticle dispersion. 99.9 wt% polyethylene was added to 40 ml xylene and magnetically stirred at 100 °C for 6 h. The nanoparticle dispersion was added to a polyethylene xylene solution and mixed at 100 °C for 10 h. The reaction solution was poured into a petri dish and placed on a hot plate at 130 °C to completely evaporate the solvent. A polyethylene composite material with a thickness of 0.2 mm was obtained by hot pressing.

[0087] Experimental Example 8 The benzotriazole derivative-grafted silica nanoparticles prepared in Example 3 were added to the polyethylene matrix at a ratio of 0.5 wt%. The specific steps were as follows: 0.5 wt% benzotriazole derivative-grafted silica nanoparticles were added to 40 ml xylene and dispersed for 30 min, then stirred at room temperature for 6 h to obtain a nanoparticle dispersion. 99.5 wt% polyethylene was added to 40 ml xylene and magnetically stirred at 100 ℃ for 6 h. The nanoparticle dispersion was added to a polyethylene xylene solution and mixed at 100 ℃ for 10 h. The reaction solution was poured into a petri dish and placed on a hot plate at 130 ℃ to completely evaporate the solvent. A polyethylene composite material with a thickness of 0.2 mm was obtained by hot pressing.

[0088] Experimental Example 9 The benzotriazole derivative-grafted silica nanoparticles prepared in Example 3 were added to the polyethylene matrix at a ratio of 1 wt%. The specific steps were as follows: 1 wt% of benzotriazole derivative-grafted silica nanoparticles were added to 40 ml of xylene and dispersed for 30 min. The mixture was stirred at room temperature for 6 h to obtain a nanoparticle dispersion. 99 wt% of polyethylene was added to 40 ml of xylene and magnetically stirred at 100 ℃ for 6 h. The nanoparticle dispersion was added to a polyethylene xylene solution and mixed at 100 ℃ for 10 h. The reaction solution was poured into a petri dish and placed on a hot plate at 130 ℃ to completely evaporate the solvent. A polyethylene composite material with a thickness of 0.2 mm was obtained by hot pressing.

[0089] Experimental Example 10 The benzotriazole derivative-grafted silica nanoparticles prepared in Example 4 were added to the polyethylene matrix at a ratio of 0.1 wt%. The specific steps were as follows: 0.1 wt% benzotriazole derivative-grafted silica nanoparticles were added to 40 ml xylene and dispersed for 30 min. The mixture was stirred at room temperature for 6 h to obtain a nanoparticle dispersion. 99.9 wt% polyethylene was added to 40 ml xylene and magnetically stirred at 100 °C for 6 h. The nanoparticle dispersion was added to a polyethylene xylene solution and mixed at 100 °C for 10 h. The reaction solution was poured into a petri dish and placed on a hot plate at 130 °C to completely evaporate the solvent. A polyethylene composite material with a thickness of 0.2 mm was obtained by hot pressing.

[0090] Experimental Example 11 The benzotriazole derivative-grafted silica nanoparticles prepared in Example 4 were added to the polyethylene matrix at a ratio of 0.5 wt%. The specific steps were as follows: 0.5 wt% benzotriazole derivative-grafted silica nanoparticles were added to 40 ml xylene and dispersed for 30 min. The mixture was stirred at room temperature for 6 h to obtain a nanoparticle dispersion. 99.5 wt% polyethylene was added to 40 ml xylene and magnetically stirred at 100 ℃ for 6 h. The nanoparticle dispersion was added to a polyethylene xylene solution and mixed at 100 ℃ for 10 h. The reaction solution was poured into a petri dish and placed on a hot plate at 130 ℃ to completely evaporate the solvent. A polyethylene composite material with a thickness of 0.2 mm was obtained by hot pressing.

[0091] Experimental Example 12 The benzotriazole derivative-grafted silica nanoparticles prepared in Example 4 were added to the polyethylene matrix at a ratio of 1 wt%. The specific steps were as follows: 1 wt% of benzotriazole derivative-grafted silica nanoparticles were added to 40 ml of xylene and dispersed for 30 min. The mixture was stirred at room temperature for 6 h to obtain a nanoparticle dispersion. 99 wt% of polyethylene was added to 40 ml of xylene and magnetically stirred at 100 ℃ for 6 h. The nanoparticle dispersion was added to a polyethylene xylene solution and mixed at 100 ℃ for 10 h. The reaction solution was poured into a petri dish and placed on a hot plate at 130 ℃ to completely evaporate the solvent. A polyethylene composite material with a thickness of 0.2 mm was obtained by hot pressing.

[0092] Experimental Example 13 (Preparation of Polyethylene Composite Materials by Blown Film Method) The benzotriazole derivative grafted silica nanoparticle additive obtained in Example 1 was blended with polyethylene at a ratio of 0.5 wt% and blown into a film to obtain a polyethylene composite material with a thickness of 24 μm.

[0093] Comparative Example 1 The final product of this comparative example was polyethylene with 0.1 wt% unmodified silica nanoparticles of 50 nm. The blending method was as follows: unmodified silica with a particle size of 50 nm was added to 40 ml of xylene and dispersed for 30 min, and stirred at room temperature for 6 h to obtain a nanoparticle dispersion; polyethylene was added to 40 ml of xylene and magnetically stirred at 100 °C for 6 h; the nanoparticle dispersion was added to the polyethylene xylene solution and blended at 100 °C for 10 h; the reaction solution was poured into a petri dish and placed on a hot plate at 130 °C to completely evaporate the solvent; and a polyethylene composite material with a thickness of 0.2 mm was obtained by hot pressing.

[0094] Comparative Example 2 The final product of this comparative example was polyethylene with 0.5 wt% unmodified silica nanoparticles of 50 nm. The blending method was as follows: unmodified silica with a particle size of 50 nm was added to 40 ml of xylene and dispersed for 30 min, and stirred at room temperature for 6 h to obtain a nanoparticle dispersion; polyethylene was added to 40 ml of xylene and magnetically stirred at 100 °C for 6 h; the nanoparticle dispersion was added to the polyethylene xylene solution and blended at 100 °C for 10 h; the reaction solution was poured into a petri dish and placed on a hot plate at 130 °C to completely evaporate the solvent; and a polyethylene composite material with a thickness of 0.2 mm was obtained by hot pressing.

[0095] Comparative Example 3 The final product of this comparative example was polyethylene with 1 wt% unmodified silica nanoparticles of 50 nm. The blending method was as follows: unmodified silica with a particle size of 50 nm was added to 40 ml of xylene and dispersed for 30 min, and stirred at room temperature for 6 h to obtain a nanoparticle dispersion; polyethylene was added to 40 ml of xylene and magnetically stirred at 100 °C for 6 h; the nanoparticle dispersion was added to the polyethylene xylene solution and blended at 100 °C for 10 h; the reaction solution was poured into a petri dish and placed on a hot plate at 130 °C to completely evaporate the solvent; and a polyethylene composite material with a thickness of 0.2 mm was obtained by hot pressing.

[0096] Comparative Example 4 The final product of this comparative example was polyethylene with 0.1 wt% unmodified silica nanoparticles of 100 nm. The blending method was as follows: unmodified silica with a particle size of 100 nm was added to 40 ml of xylene and dispersed for 30 min, and stirred at room temperature for 6 h to obtain a nanoparticle dispersion; polyethylene was added to 40 ml of xylene and magnetically stirred at 100 °C for 6 h; the nanoparticle dispersion was added to the polyethylene xylene solution and blended at 100 °C for 10 h; the reaction solution was poured into a petri dish and placed on a hot plate at 130 °C to completely evaporate the solvent; and a polyethylene composite material with a thickness of 0.2 mm was obtained by hot pressing.

[0097] Comparative Example 5 The final product of this comparative example was polyethylene with 0.5 wt% of 100 nm unmodified silica nanoparticles. The blending method was as follows: 100 nm unmodified silica was added to 40 ml of xylene and dispersed for 30 min, then stirred at room temperature for 6 h to obtain a nanoparticle dispersion; polyethylene was added to 40 ml of xylene and magnetically stirred at 100 °C for 6 h; the nanoparticle dispersion was added to the polyethylene xylene solution and blended at 100 °C for 10 h; the reaction solution was poured into a petri dish and placed on a hot plate at 130 °C to completely evaporate the solvent; and a polyethylene composite material with a thickness of 0.2 mm was obtained by hot pressing.

[0098] Comparative Example 6 The final product of this comparative example was polyethylene with 1 wt% unmodified silica nanoparticles of 100 nm. The blending method was as follows: unmodified silica with a particle size of 100 nm was added to 40 ml of xylene and dispersed for 30 min, and stirred at room temperature for 6 h to obtain a nanoparticle dispersion; polyethylene was added to 40 ml of xylene and magnetically stirred at 100 °C for 6 h; the nanoparticle dispersion was added to the polyethylene xylene solution and blended at 100 °C for 10 h; the reaction solution was poured into a petri dish and placed on a hot plate at 130 °C to completely evaporate the solvent; and a polyethylene composite material with a thickness of 0.2 mm was obtained by hot pressing.

[0099] Comparative Example 7 In this comparative example, polyethylene was added to 40 ml of xylene and magnetically stirred at 100°C for 16 h. The reaction solution was then poured into a petri dish and placed on a hot plate at 130°C to completely evaporate the solvent. A polyethylene composite material with a thickness of 0.2 mm was obtained by hot pressing.

[0100] Comparative Example 8 Unlike Experimental Example 2, the silane coupling agent-modified inorganic nanoparticles obtained in step S2 of Example 1 were directly added to the polyethylene matrix at a ratio of 0.5 wt%. The specific steps are as follows: (1) Prepare inorganic nanoparticles modified with silane coupling agent. The preparation method is exactly the same as steps S1 and S2 in Example 1. (2) Add 0.5 wt% silane coupling agent modified inorganic nanoparticles to 40 ml xylene and disperse for 30 min. Stir at room temperature for 6 h to obtain nanoparticle dispersion. Add 99.5 wt% polyethylene to 40 ml xylene and stir magnetically at 100 ℃ for 6 h. Add nanoparticle dispersion to polyethylene xylene solution and mix at 100 ℃ for 10 h. Pour the reaction solution into a petri dish and place it on a hot table at 130 ℃ to evaporate the solvent to obtain the final product.

[0101] The performance of the polyethylene composite materials obtained in Experimental Examples 1-13 and Comparative Examples 1-8 was tested, and the test results are shown in Table 3.

[0102]

[0103] in conclusion: 1. The additive of the present invention can significantly reduce the haze of the film while maintaining high light transmittance. Compared with pure polyethylene matrix (Comparative Example 7, haze 71.6%), unmodified nanoparticles of the same particle size and amount (Comparative Examples 1-6, haze 66.7%-78%), and silane coupling agent modified only (Comparative Example 8, haze 65.7%), the light transmittance of all experimental examples of the present invention is ≥85% (maximum 88.8%), and the haze is <60% (minimum 38.8%), with a significant reduction in haze. Meanwhile, industrial blown film verification (Experimental Example 13) achieved 91.8% light transmittance and 6.9% ultra-low haze, fully meeting the needs of industrial applications.

[0104] 2. The additive of this invention can simultaneously improve the tensile strength of polyethylene, avoiding the common industry problem of reduced permeability and mechanical strength caused by conventional nanofillers: compared with pure polyethylene matrix (Comparative Example 7), unmodified nanoparticle group with the same amount of additive, and silane-modified group, the tensile strength of all experimental examples is significantly improved, proving that grafting modification can significantly improve the interfacial bonding between nanoparticles and matrix, and give full play to the reinforcing effect of inorganic particles.

[0105] 3. The melt flow rate (MI) is evaluated based on the reference value of pure polyethylene matrix (Comparative Example 7, 7.529 g / 10 min). The closer the value is to the reference value and the smaller the absolute deviation, the better the processing stability and adaptability to the production line.

[0106] All experimental examples of this invention showed significantly less negative impact on the processing flowability of polyethylene than the control group of unmodified / silane-modified nanoparticles with the same particle size and addition amount. Among them, the MI value of Experimental Example 8 was almost completely the same as that of pure polyethylene, and the original processing performance was completely preserved.

[0107] This invention fundamentally solves the problem of deteriorated polyethylene processing fluidity caused by conventional nanofillers. It has minimal impact on processing fluidity, requires no modification to existing production lines, and can be directly adapted to industrial blown film, cast film and other mass production processes. It exhibits excellent processing adaptability and production stability.

[0108] In summary, the benzotriazole derivative-grafted nanoparticle additive prepared by this invention completely solves the core problems of poor compatibility between nanoparticles and polyethylene, easy agglomeration, high haze, and poor processing stability in the prior art. It can simultaneously achieve synergistic improvement of the optical, mechanical, and processing properties of materials. The process is controllable and the cost is low, possessing extremely high creativity and industrialization promotion value.

[0109] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing a benzotriazole derivative-grafted nanoparticle additive, characterized in that, Includes the following steps: (1) Preparation of inorganic nanoparticles modified with silane coupling agent; (2) The benzotriazole derivative was subjected to terminal epoxidation and hydroxyl protection treatment in sequence to obtain hydroxyl-protected epoxy benzotriazole derivative; (3) The inorganic nanoparticles modified by the silane coupling agent are reacted with the hydroxyl-protected epoxy benzotriazole derivative to obtain the benzotriazole derivative grafted nanoparticle additive.

2. The preparation method according to claim 1, characterized in that, In step (1), the silane coupling agent is a silane coupling agent with an amino functional group in its molecular structure; Preferably, the silane coupling agent is selected from at least one of (3-aminopropyl)trimethoxysilane, (3-aminopropyl)triethoxysilane, and 3-[2-(2-aminoethylamino)ethylamino]propyl-trimethoxysilane; Preferably, in step (1), the inorganic nanoparticles are silicon dioxide nanoparticles. Preferably, the particle size of the silica nanoparticles is 15~500 nm; more preferably 50~100 nm. Preferably, in step (1), the mass ratio of the inorganic nanoparticles to the silane coupling agent is (2~1): (1~6); more preferably, it is 1: (1~2).

3. The preparation method according to claim 1 or 2, characterized in that, Step (1) includes: dispersing inorganic nanoparticles in a first organic solvent, then adding a silane coupling agent to react and obtain silane coupling agent modified inorganic nanoparticles; Preferably, the first organic solvent is selected from at least one of toluene and xylene; Preferably, in step (1), the inorganic nanoparticles are dispersed in a first organic solvent after ultrasonic treatment; Preferably, in step (1), the ultrasonic treatment time is 0.1~2h; Preferably, in step (1), the reaction temperature is 100~120℃ and the reaction time is 12~24h; Preferably, in step (1), the reaction is carried out under the protection of an inert gas.

4. The preparation method according to claim 1, characterized in that, In step (2), the benzotriazole derivative is a benzotriazole derivative containing an epoxidizable unsaturated bond; Preferably, the benzotriazole derivative is selected from at least one of 2-(2H-benzotriazole-2-yl)-4-methyl-6-(2-methyl-2-propenyl)phenol, 2-allyl-6-(2H-benzo[d][1,2,3]triazole-2-yl)-4-methylphenol, ethyl 2-[3-(2H-benzotriazole-2-yl)-4-hydroxyphenyl]methacrylate, and 1-[(1-vinyl)-3-butenyl]-1H-benzotriazole.

5. The preparation method according to any one of claims 1-4, characterized in that, In step (2), the end-group epoxidation treatment includes: reacting the benzotriazole derivative with the first modifier in a second organic solvent to obtain a benzotriazole derivative with an epoxy group at the end group; Preferably, the first modifier is selected from at least one of m-chloroperoxybenzoic acid, peroxybenzoic acid, and dimethyldioxane; Preferably, the molar ratio of the benzotriazole derivative to the first modifier is 1:(1.0-1.2); Preferably, the second organic solvent is selected from at least one of xylene and dichloromethane; Preferably, in the end-group epoxidation treatment, the reaction temperature is 20-30℃ and the reaction time is 10-15 hours; Preferably, the end-group epoxidation treatment is performed under inert gas protection; Preferably, in the terminal epoxidation treatment, after the reaction is completed, a benzotriazole derivative with an epoxy group at the end is obtained by separation and purification; preferably, the separation and purification is performed by column chromatography.

6. The preparation method according to any one of claims 1-5, characterized in that, In step (2), the hydroxyl protection treatment includes: reacting the benzotriazole derivative treated with terminal group epoxidation with a second modifier in a third organic solvent to obtain a hydroxyl-protected epoxy benzotriazole derivative. Preferably, the second modifier is selected from at least one of tert-butyldimethylchlorosilane, trimethylsilyl, and triethylsilyl; Preferably, the third organic solvent is selected from at least one of xylene and dichloromethane; Preferably, in the hydroxyl protection treatment, the reaction temperature is 20-30°C and the reaction time is 10-15 hours; Preferably, the hydroxyl protection treatment is performed under an inert gas atmosphere; Preferably, in the hydroxyl protection treatment, after the reaction is completed, the hydroxyl-protected epoxybenzotriazole derivative is obtained by separation and purification; preferably, the separation and purification is performed by column chromatography.

7. The preparation method according to any one of claims 1-6, characterized in that, In step (3), the mass ratio of the hydroxyl-protected epoxy benzotriazole derivative to the silane coupling agent modified inorganic nanoparticles is (0.3~1.0): 0.

25.

8. The preparation method according to any one of claims 1-7, characterized in that, Step (3) includes: dispersing the silane coupling agent modified inorganic nanoparticles in a fourth organic solvent, and then adding the hydroxyl-protected epoxy benzotriazole derivative to react and obtain the benzotriazole derivative grafted nanoparticle additive. Preferably, the fourth organic solvent is selected from at least one of toluene and xylene; Preferably, the reaction temperature is 100-120℃ and the reaction time is 10-15 hours; Preferably, in step (3), the reaction is carried out under the protection of an inert gas.

9. A benzotriazole derivative grafted nanoparticle additive prepared by the method according to any one of claims 1-8; Preferably, the grafting density of the benzotriazole derivative in the benzotriazole derivative-grafted nanoparticle additive is 3.6~9.0 chains / nm².

10. A polyethylene composite material, characterized in that, Includes polyethylene and the benzotriazole derivative grafted nanoparticle additive as described in claim 9; Preferably, the benzotriazole derivative-grafted nanoparticle additive in the polyethylene composite material has a mass fraction of 0.1 wt% to 1.0 wt%. Preferably, the polyethylene composite material is prepared by dispersing polyethylene and the benzotriazole derivative grafted nanoparticle additive in an organic solvent and then evaporating the organic solvent to obtain the polyethylene composite material. Preferably, the organic solvent is toluene or xylene; Preferably, the blending temperature is 90~130℃ and the blending time is 10~24h; Preferably, the organic solvent is evaporated at 100~130°C to obtain the polyethylene composite material; Preferably, the polyethylene composite material is a polyethylene film; Preferably, the light transmittance of the polyethylene film is >85%; Preferably, the haze of the polyethylene film is <60%; More preferably, the haze of the polyethylene film is <40%.

Images