A new type of composite gas phase antirust film and its manufacturing method

Abstract

This application relates to the technical field of metal rust-preventive packaging materials, specifically disclosing a novel composite vapor phase rust inhibitor film and its manufacturing method. The novel composite vapor phase rust inhibitor film comprises the following raw materials in parts by weight: 20-30 parts halloysite nanotubes, 15-20 parts phytic acid, 5-8 parts benzotriazole, 3-5 parts ammonium molybdate, 1-3 parts epoxidized soybean oil, 4-6 parts polyethylene grafted with maleic anhydride, 70-80 parts linear low-density polyethylene, and 8-12 parts low-density polyethylene. This application uses halloysite nanotubes as nanocontainers to provide confined space, thereby utilizing the steric hindrance effect of the nanotube cavity to allow corrosion inhibitor components with different volatilization rates to be released through the nanotube opening at similar diffusion rates. This suppresses the rapid escape of highly volatile components and the delayed release of low-volatile components, ensuring that multiple corrosion inhibitors volatilize essentially synchronously throughout the entire service life, achieving balanced protection for various metals such as steel, copper, and aluminum alloys.

Description

Technical Field

[0001] This application relates to the field of metal anti-rust packaging materials technology, and more specifically, it relates to a novel composite vapor phase anti-rust film and its manufacturing method. Background Technology

[0002] Vapor phase corrosion inhibitor film is a functional packaging material made by co-extruding and blow molding a vapor phase corrosion inhibitor into a polyolefin resin. During use, the vapor phase corrosion inhibitor slowly evaporates from the resin matrix into the packaging space, forming a protective layer of monomolecular thickness on the metal surface. This inhibits the contact between the metal and corrosive media such as oxygen and water vapor, achieving non-contact rust prevention protection. Due to its advantages such as ease of use, no residue, and ability to cover complex-shaped workpieces, vapor phase corrosion inhibitor film has been widely used in rust prevention packaging for automotive engine assemblies, gearbox housings, metal assemblies in industrial machinery and equipment, as well as precision machinery and electronic components.

[0003] Existing vapor phase corrosion inhibitors (VPI) are mostly made by directly blending polyethylene resin with vapor phase corrosion inhibitors such as sodium nitrite, sodium benzoate, and dicyclohexylamine octanoate, as well as fillers such as silica, and then blow molding. For example, an automotive engine assembly contains multiple metal parts such as a cast iron cylinder block, copper alloy electrical terminals, and an aluminum alloy cylinder head. However, different vapor phase corrosion inhibitor components have naturally different volatilization rates. When these components are blended and dispersed in a polyolefin matrix, they are released independently according to their own diffusion coefficients and volatilization rates. In the early stages of film use, highly volatile components are released rapidly and reach a high concentration in the packaging space, providing excessive protection to the corresponding metal, while low-volatile components are released insufficiently and cannot form an effective protective concentration for the target metal. As the usage time increases, the highly volatile components are rapidly consumed, and only then do the low-volatile components begin to enter the effective release stage, resulting in an uneven actual protective effect of the VPI on different metals. Summary of the Invention

[0004] To address the issue of uneven protective effects of existing vapor phase corrosion inhibitors on different metals, this application provides a novel composite vapor phase corrosion inhibitor and its manufacturing method.

[0005] This application provides a novel composite vapor phase rust inhibitor film and its manufacturing method, which adopts the following technical solution: In a first aspect, this application provides a novel composite vapor phase rust inhibitor film, which adopts the following technical solution: A novel composite vapor phase rust inhibitor film comprises the following raw materials in parts by weight: halloysite nanotubes 20-30 parts, phytic acid 15-20 parts, benzotriazole 5-8 parts, ammonium molybdate 3-5 parts, epoxidized soybean oil 1-3 parts, polyethylene grafted maleic anhydride 4-6 parts, linear low-density polyethylene 70-80 parts, and low-density polyethylene 8-12 parts.

[0006] By adopting the above technical solution, halloysite nanotubes are used as nanocontainers to provide confined space. Phytic acid, benzotriazole, and ammonium molybdate, as vapor-phase corrosion inhibitors with different volatility characteristics, are jointly loaded in the nanotubes. Epoxidized soybean oil is used as a crosslinking agent to regulate the release channels of the corrosion inhibitors. Polyethylene grafted with maleic anhydride improves the interfacial compatibility between the inorganic filler and the polyethylene matrix. Linear low-density polyethylene and low-density polyethylene together constitute the film-forming matrix. Thus, the steric hindrance effect of the nanotube cavity is utilized to allow corrosion inhibitor components with different volatilization rates to be released through the nanotube opening at similar diffusion rates. This suppresses the rapid escape of high-volatility components and the delayed release of low-volatility components, allowing multiple corrosion inhibitors to volatilize essentially synchronously throughout the entire service life. This achieves balanced protection for multiple metals such as steel, copper, and aluminum alloys, thereby meeting the rust prevention requirements of multi-metal assemblies such as automotive engine assemblies and industrial machinery during long-term storage. This solves the problem of uneven actual protective effects of existing vapor-phase rust inhibitors on different metals.

[0007] Preferably, the phytic acid is an aqueous solution of phytic acid with a mass fraction of 45-55%.

[0008] By adopting the above technical solution, the mass fraction of the phytic acid aqueous solution can ensure that the phytic acid has suitable fluidity and reactivity during the impregnation process. This is conducive to the phytic acid fully entering the halloysite nanotube cavity and coordinating with the aluminum hydroxyl groups on the inner wall of the tube. Combined with the subsequent heat treatment fixation step, a stable and solvent-insoluble three-dimensional cross-linked network can be formed, ensuring that the phytic acid loaded in the inner layer is not washed away during the outer layer impregnation process, thereby maintaining the axial partitioned structure.

[0009] Preferably, the halloysite nanotubes have a diameter of 15-30 nm and a length of 0.5-1.5 μm.

[0010] By adopting the above technical solution, the inner cavity of halloysite nanotubes can accommodate corrosion inhibitor molecules such as phytic acid, benzotriazole and ammonium molybdate. At the same time, the confinement effect of the cavity is sufficient to change the diffusion dynamics of small molecule corrosion inhibitors, so that corrosion inhibitors of different molecular sizes can obtain similar effective diffusion coefficients. In addition, it also has a good aspect ratio, and can be oriented and aligned along the flow direction during the film blow molding process, thereby improving the water vapor barrier performance of the film.

[0011] Preferably, the grafting rate of the polyethylene grafted with maleic anhydride is 0.8-1.2%.

[0012] By adopting the above technical solution, polyethylene grafted with maleic anhydride at a grafting rate of 0.8-1.2% has an appropriate amount of maleic anhydride active groups, which can undergo esterification reaction with the hydroxyl groups on the outer surface of halloysite nanotubes to achieve covalent grafting, so that the outer surface of the filler is covered with polyethylene segments, thereby improving the tensile strength of the film and avoiding the decrease in mechanical properties caused by filler agglomeration.

[0013] Preferably, it also includes 1-2 parts of dispersant and 0.1-0.5 parts of antioxidant.

[0014] By adopting the above technical solutions, the dispersant can promote the uniform dispersion of the composite corrosion inhibitor filler in the polyethylene matrix, avoid the agglomeration of filler to form stress concentration points, thereby maintaining the mechanical properties and appearance quality of the film. The antioxidant can inhibit the thermal oxidative degradation of the polyethylene matrix during processing and use, extend the service life of the film, and enable the film to maintain excellent rust prevention performance while also having good processing stability and long-term reliability.

[0015] Secondly, this application provides a method for manufacturing a novel composite vapor phase rust inhibitor film, which adopts the following technical solution: A method for manufacturing a novel composite vapor phase rust inhibitor film includes the following steps: S1. After acid activation, halloysite nanotubes are subjected to the following steps: inner layer phytic acid loading, intermediate heat treatment fixation, outer layer benzotriazole and ammonium molybdate loading, port epoxidized soybean oil crosslinking sealing, and outer surface polyethylene grafting with maleic anhydride to obtain composite corrosion inhibitor filler. S2. The composite corrosion inhibitor filler is blended and granulated with linear low-density polyethylene, low-density polyethylene, dispersant and antioxidant to obtain rust-preventive masterbatch. S3. The rust-preventive masterbatch is co-extruded and blown into a film to obtain a novel composite vapor phase rust-preventive film.

[0016] By adopting the above technical solution, low-volatility phytic acid is loaded and fixed in the inner layer of nanotubes, and high-volatility benzotriazole and ammonium molybdate are loaded in the outer layer, forming an axial partitioned structure. The port epoxy soybean oil crosslinking sealing layer controls the diffusion and release rate of the corrosion inhibitor, and the outer surface grafting layer improves the compatibility between the filler and the matrix. Together, they ensure the complete structure and function of the composite corrosion inhibitor filler, thereby creating a vapor phase rust inhibitor film that can achieve simultaneous release of multiple components and balanced protection for multiple metals.

[0017] Preferably, in step S1, the acid activation involves adding halloysite nanotubes to a 1.5 mol / L hydrochloric acid solution, stirring and activating at 68-72°C for 2.5-3.5 hours, washing until the pH is 6-7, and then drying. The inner phytic acid loading involves immersing the acid-activated halloysite nanotubes in a phytic acid aqueous solution under a vacuum of -0.095 to -0.098 MPa for 3.5-4.5 hours, and then vacuum drying at 48-52°C. The intermediate heat treatment fixation involves heat treatment at 79-81°C for 2 hours. The outer benzotriazole and ammonium molybdate loading involves immersing the outer benzotriazole and ammonium molybdate in an anhydrous ethanol solution under a vacuum of -0.095 to -0.098 MPa for 2.5-3.5 hours, and then vacuum drying at 43-47°C.

[0018] By adopting the above technical solutions, acid activation can remove impurities on the surface of halloysite nanotubes and expose the hydroxyl groups on the inner and outer surfaces. Vacuum impregnation uses negative pressure to draw the solution into the nanotube cavity, ensuring that phytic acid fully enters the tube. Heat treatment causes phytic acid to undergo cross-linking polymerization, forming a network structure that is insoluble in anhydrous ethanol, preventing the phytic acid from being washed away during subsequent outer layer impregnation. Anhydrous ethanol is used as a solvent for outer layer impregnation, avoiding the swelling and loss of the fixed phytic acid, thus jointly ensuring the formation and stability of the axial partitioned load structure.

[0019] Preferably, in step S1, the port-side epoxidized soybean oil crosslinking and sealing involves dispersing the loaded halloysite nanotubes in anhydrous ethanol to prepare a suspension with a mass fraction of 5-10%, adding a dilute solution of epoxidized soybean oil in anhydrous ethanol, wherein the mass-to-volume ratio of epoxidized soybean oil to anhydrous ethanol is 1g:9-11mL, and the addition time is 30-60 minutes. Then, the temperature is raised to 48-52℃ and the reaction is carried out for 1-1.5 hours. Triethylamine with a weight of 0.3-0.6% of epoxidized soybean oil is added and the reaction is continued for 1.5-2.5 hours. After filtration and washing, the mixture is vacuum dried at 43-47℃.

[0020] By adopting the above technical solution, the loaded nanotubes are formulated into a suspension, which facilitates the uniform contact of epoxidized soybean oil molecules with the nanotubes in the ethanol medium. The dilute solution of epoxidized soybean oil is added dropwise, and the high surface energy of the nanotube ports preferentially adsorbs the epoxidized soybean oil, thereby achieving selective sealing of the end groups. Under the catalytic condition of triethylamine, the epoxy groups in the epoxidized soybean oil undergo a ring-opening cross-linking reaction with the hydroxyl groups at the ports to form a semi-permeable sealing layer. This allows the corrosion inhibitor molecules to diffuse and release slowly, while effectively controlling the release rate of different components, so that phytic acid, benzotriazole, and ammonium molybdate escape through the ports at similar rates.

[0021] Preferably, in step S1, the outer surface polyethylene grafted with maleic anhydride is prepared by reacting the sealed halloysite nanotubes with polyethylene grafted with maleic anhydride in toluene under reflux at 78-82°C for 1.5-2.5 hours, and the mass fraction of the toluene solution of polyethylene grafted with maleic anhydride is 2-3%. After the reaction, the mixture is filtered, washed successively with hot toluene and anhydrous ethanol, and then vacuum dried at 58-62°C.

[0022] By adopting the above technical solution, grafting the outer surface after the port sealing is completed can avoid the grafting reaction affecting the corrosion inhibitor inside the tube. The reflux temperature dissolves the polyethylene-grafted maleic anhydride in toluene, and the maleic anhydride groups in its molecular chain undergo esterification with the hydroxyl groups exposed on the outer surface of the nanotube. The solution concentration can ensure sufficient grafting density, while avoiding excessive viscosity from affecting the uniformity of the reaction. After grafting, washing with hot toluene and anhydrous ethanol in sequence can remove unreacted polyethylene-grafted maleic anhydride and residual solvent. This outer surface grafting layer covers the outer surface of the filler with polyethylene segments, forming good interfacial compatibility with the matrix resin of subsequent blending, improving the dispersion state and interfacial bonding strength of the filler in the film.

[0023] Preferably, in step S2, the temperature of the twin-screw extruder for granulation is 145-160℃ and the screw speed is 180-220rpm; In step S3, the co-extruded blown film includes an inner layer, an intermediate layer, and an outer layer, and the dilution mass ratios of the rust-preventive masterbatch of the inner layer, the intermediate layer, and the outer layer to linear low-density polyethylene are 1:0.8-1.2, 1:1.5-2.5, and 1:3.5-4.5, respectively. The blown film die temperature is 155-170℃, the blow-up ratio is 2.5-3, and the total film thickness is 50-80μm.

[0024] By adopting the above technical solution, the twin-screw extrusion granulation temperature is lower than the thermal decomposition temperature of the vapor phase corrosion inhibitor, avoiding excessive volatilization loss of the corrosion inhibitor during processing. The three-layer co-extrusion blown film adopts a gradient distribution design with high concentration in the inner layer and low concentration in the outer layer. The higher VCI concentration in the inner layer ensures that the packaging space near the metal surface has sufficient effective concentration, while the lower VCI concentration in the outer layer reduces the ineffective volatilization of the corrosion inhibitor into the external environment. The die temperature and blow-up ratio ensure the forming quality and mechanical properties of the film, thereby further optimizing the spatial distribution and utilization efficiency of the corrosion inhibitor, extending the effective rust prevention period while ensuring balanced protection of multiple metals.

[0025] In summary, this application has the following beneficial effects: 1. This application utilizes halloysite nanotubes as nanocontainers to provide confined space. Phytic acid, benzotriazole, and ammonium molybdate, as vapor-phase corrosion inhibitors with different volatility characteristics, are jointly loaded within the nanotubes. Epoxidized soybean oil acts as a crosslinking agent to regulate the release channels of the corrosion inhibitors. Polyethylene grafted with maleic anhydride improves the interfacial compatibility between the inorganic filler and the polyethylene matrix. Linear low-density polyethylene and low-density polyethylene together constitute the film-forming matrix. Thus, by utilizing the steric hindrance effect of the nanotube cavity, corrosion inhibitor components with different volatilization rates are released through the nanotube openings at similar diffusion rates. This suppresses the rapid escape of high-volatility components and the delayed release of low-volatility components, allowing multiple corrosion inhibitors to volatilize essentially synchronously throughout the entire service life. This achieves balanced protection for various metals such as steel, copper, and aluminum alloys, thereby meeting the rust prevention requirements of multi-metal assemblies such as automotive engine assemblies and industrial machinery during long-term storage. This solves the problem of uneven actual protective effects of existing vapor-phase rust inhibitors on different metals.

[0026] 2. This application modifies the outer surface of halloysite nanotubes by grafting maleic anhydride onto polyethylene, thereby covering the outer surface with polyethylene segments that are highly compatible with the polyethylene matrix. This improves the dispersion uniformity and interfacial bonding strength of the composite corrosion inhibitor filler in linear low-density polyethylene and low-density polyethylene matrices. The outer surface graft layer enables the filler to form good interfacial compatibility with the matrix resin, forming a uniformly dispersed reinforcing network and labyrinthine barrier structure in the film. While ensuring rust prevention performance, it effectively improves the mechanical load-bearing capacity and water vapor barrier performance of the film.

[0027] 3. This application uses intermediate heat treatment to fix the phytic acid in the inner layer to undergo cross-linking polymerization, forming a network structure insoluble in anhydrous ethanol. This prevents the phytic acid from being washed away during the outer layer loading process and maintains the integrity of the axial partitioned loading structure. A semi-permeable sealing layer is formed by cross-linking and sealing with epoxy soybean oil at the port, allowing the corrosion inhibitor to be released slowly at a controllable rate. A gradient distribution structure with a high concentration in the inner layer and a low concentration in the outer layer is formed by three-layer co-extrusion blown film. The higher concentration of corrosion inhibitor in the inner layer ensures that the packaging space near the metal surface has a sufficient effective concentration, while the lower concentration in the outer layer reduces ineffective volatilization into the external environment. This not only extends the effective rust prevention period of the film but also avoids the pollution problem caused by the migration and precipitation of corrosion inhibitor to the film surface, allowing the film to maintain stable protective performance and a clean surface condition during long-term use. Attached Figure Description

[0028] Figure 1 This is a flowchart of a method for manufacturing a novel composite vapor phase rust inhibitor provided in this application. Detailed Implementation

[0029] The present application will be further described in detail below with reference to the accompanying drawings and embodiments.

[0030] Technical Concept: Vapor phase corrosion inhibitors are widely used in the field of metal rust prevention packaging. Existing technologies attempt to use a combination of various vapor phase corrosion inhibitors such as phytic acid, benzotriazole, and ammonium molybdate to achieve comprehensive protection for multi-metal assemblies such as steel, copper, and aluminum alloys. However, different vapor phase corrosion inhibitor components have naturally different volatilization rates. Benzotriazole has a small molecular weight and high saturated vapor pressure, so it volatilizes quickly, while phytic acid has a large molecular weight and strong polarity, so it volatilizes relatively slowly. When these components are simply blended and dispersed in a polyolefin matrix, they are released independently according to their own diffusion coefficient and volatilization rate. As a result, there is never a window period in the entire rust prevention cycle during which all corrosion inhibitor components reach an effective protective concentration at the same time. This leads to uneven protective effects of existing broad-spectrum vapor phase corrosion inhibitors on different metals.

[0031] Based on the above findings, this application first loads low-volatility phytic acid onto the inner layer of nanotubes and fixes it through heat treatment to form a cross-linked network insoluble in anhydrous ethanol. Then, highly volatile benzotriazole and ammonium molybdate are loaded onto the outer layer of nanotubes. The ends are sealed with epoxidized soybean oil to form a semi-permeable controlled-release layer. Finally, maleic anhydride is grafted onto the outer surface of polyethylene to improve compatibility with the polyethylene matrix. The combination of these steps enables corrosion inhibitor components with different volatilization rates to be released at a basically synchronous rate throughout the entire service life. In addition, the above-mentioned composite corrosion inhibitor filler is blended with the polyethylene matrix and then subjected to a three-layer co-extrusion blown film process to form a gradient distribution structure with a high concentration in the inner layer and a low concentration in the outer layer. This can further reduce the ineffective volatilization of corrosion inhibitors into the external environment and achieve balanced protection for various metals such as steel, copper, and aluminum alloys. This meets the rust prevention requirements of multi-metal assemblies such as automotive engine assemblies and industrial machinery during long-term storage and solves the problem of uneven actual protection effect of existing vapor phase rust inhibitors on different metals.

[0032] Unless otherwise specified, all experimental methods used below are conventional methods. All materials, reagents, methods, and instruments used, unless otherwise specified, are conventional materials, reagents, methods, and instruments in this field, which can be obtained commercially or prepared according to literature methods by those skilled in the art.

[0033] To better understand the above technical solutions, the technical solutions of the present invention will be clearly and completely described below in conjunction with embodiments.

[0034] Please see the appendix Figure 1 The following is a further description with reference to the embodiments: Example 1: A novel composite vapor phase rust inhibitor film, comprising the following raw materials in parts by weight: 25 parts halloysite nanotubes, 17.5 parts phytic acid, 6.5 parts benzotriazole, 4 parts ammonium molybdate, 2 parts epoxidized soybean oil, 5 parts polyethylene grafted with maleic anhydride, 75 parts linear low-density polyethylene, and 10 parts low-density polyethylene.

[0035] Phytic acid is a 50% (w / w) aqueous solution of phytic acid.

[0036] Halloysite nanotubes have a diameter of 22.5 nm and a length of 1 μm.

[0037] The grafting rate of maleic anhydride onto polyethylene was 1%.

[0038] It also includes 1.5 parts of dispersant and 0.3 parts of antioxidant. The dispersant is polyethylene wax and the antioxidant is antioxidant 1010.

[0039] A method for manufacturing a novel composite vapor phase rust inhibitor film, applicable to the aforementioned novel composite vapor phase rust inhibitor film, includes the following steps: S1. After acid activation, halloysite nanotubes are subjected to the following steps: inner layer phytic acid loading, intermediate heat treatment fixation, outer layer benzotriazole and ammonium molybdate loading, port epoxidized soybean oil crosslinking sealing, and outer surface polyethylene grafting with maleic anhydride to obtain composite corrosion inhibitor filler. The acid activation process involved adding halloysite nanotubes to a 1.5 mol / L hydrochloric acid solution, stirring at 70°C for 3 hours, washing until the pH reached 6-7, and then drying. The inner phytic acid loading process involved immersing the acid-activated halloysite nanotubes in a phytic acid aqueous solution under a vacuum of -0.0965 MPa for 4 hours, followed by vacuum drying at 50°C. The intermediate heat treatment fixation process involved heat treatment at 80°C for 2 hours. The outer benzotriazole and ammonium molybdate loading process involved immersing the nanotubes in an anhydrous ethanol solution of benzotriazole and ammonium molybdate under a vacuum of -0.0965 MPa for 3 hours, followed by vacuum drying at 45°C. The cross-linking and sealing of the port with epoxidized soybean oil was carried out by dispersing the loaded halloysite nanotubes in anhydrous ethanol to prepare a suspension with a mass fraction of 7.5%, adding anhydrous ethanol dilute solution of epoxidized soybean oil dropwise at a mass-volume ratio of 1g:10mL over 45 minutes, then heating to 50℃ and reacting for 1.25 hours, adding 0.45% by weight of triethylamine of epoxidized soybean oil and continuing the reaction for 2 hours, filtering and washing, and then vacuum drying at 45℃. The outer surface of polyethylene grafted with maleic anhydride was prepared by reacting sealed halloysite nanotubes with polyethylene grafted with maleic anhydride in toluene under reflux at 80°C for 2 hours, with the mass fraction of the toluene solution of polyethylene grafted with maleic anhydride being 2.5%. After the reaction, the mixture was filtered, washed successively with hot toluene and anhydrous ethanol, and then vacuum dried at 60°C.

[0040] S2. The composite corrosion inhibitor filler is blended with linear low-density polyethylene, low-density polyethylene, dispersant and antioxidant and granulated to obtain rust-preventive masterbatch. The twin-screw extruder used for granulation operates at a temperature of 152.5℃ and a screw speed of 200 rpm.

[0041] S3. The rust-preventive masterbatch is co-extruded and blown into a film to obtain a novel composite vapor phase rust-preventive film.

[0042] The co-extruded blown film includes an inner layer, an intermediate layer, and an outer layer. The dilution mass ratios of the rust-preventive masterbatch to the linear low-density polyethylene in the inner, intermediate, and outer layers are 1:1, 1:2, and 1:4, respectively. The blown film die temperature is 162.5℃, the blow-up ratio is 2.75, and the total film thickness is 65μm.

[0043] Example 2: This example differs from Example 1 above in that: A novel composite vapor phase rust inhibitor film comprises the following raw materials in parts by weight: 30 parts halloysite nanotubes, 20 parts phytic acid, 8 parts benzotriazole, 5 parts ammonium molybdate, 3 parts epoxidized soybean oil, 6 parts polyethylene grafted with maleic anhydride, 80 parts linear low-density polyethylene, and 12 parts low-density polyethylene.

[0044] Phytic acid is a 55% (w / w) aqueous solution of phytic acid.

[0045] Halloysite nanotubes have a diameter of 30 nm and a length of 1.5 μm.

[0046] The grafting rate of polyethylene grafted with maleic anhydride was 1.2%.

[0047] It also includes 2 parts dispersant and 0.5 parts antioxidant.

[0048] A method for manufacturing a novel composite vapor phase rust inhibitor film, applicable to the aforementioned novel composite vapor phase rust inhibitor film, includes the following steps: S1. After acid activation, halloysite nanotubes are subjected to the following steps: inner layer phytic acid loading, intermediate heat treatment fixation, outer layer benzotriazole and ammonium molybdate loading, port epoxidized soybean oil crosslinking sealing, and outer surface polyethylene grafting with maleic anhydride to obtain composite corrosion inhibitor filler. The acid activation process involved adding halloysite nanotubes to a 1.5 mol / L hydrochloric acid solution, stirring at 72°C for 3.5 hours, washing until the pH reached 7, and then drying. The inner phytic acid loading process involved immersing the acid-activated halloysite nanotubes in a phytic acid aqueous solution under a vacuum of -0.098 MPa for 4.5 hours, followed by vacuum drying at 52°C. The intermediate heat treatment fixation process involved heat treatment at 81°C for 2 hours. The outer benzotriazole and ammonium molybdate loading process involved immersing the nanotubes in an anhydrous ethanol solution of benzotriazole and ammonium molybdate under a vacuum of -0.098 MPa for 3.5 hours, followed by vacuum drying at 47°C. The cross-linking and sealing of the port with epoxidized soybean oil was carried out by dispersing the loaded halloysite nanotubes in anhydrous ethanol to prepare a suspension with a mass fraction of 10%, and then adding a dilute solution of epoxidized soybean oil in anhydrous ethanol at a mass-volume ratio of 1g:11mL over a period of 60 minutes. The temperature was then raised to 52℃ and reacted for 1.5 hours. Triethylamine at a weight of 0.6% of the epoxidized soybean oil was added and the reaction was continued for another 2.5 hours. After filtration and washing, the mixture was vacuum dried at 47℃. The outer surface of polyethylene grafted with maleic anhydride was prepared by reacting sealed halloysite nanotubes with polyethylene grafted with maleic anhydride in toluene under reflux at 82°C for 2.5 hours, with the mass fraction of the polyethylene-grafted maleic anhydride toluene solution being 3%. After the reaction, the mixture was filtered, washed successively with hot toluene and anhydrous ethanol, and then vacuum dried at 62°C.

[0049] S2. The composite corrosion inhibitor filler is blended with linear low-density polyethylene, low-density polyethylene, dispersant and antioxidant and granulated to obtain rust-preventive masterbatch. The twin-screw extruder used for granulation operates at a temperature of 160℃ and a screw speed of 220rpm.

[0050] S3. The rust-preventive masterbatch is co-extruded and blown into a film to obtain a novel composite vapor phase rust-preventive film.

[0051] The co-extruded blown film includes an inner layer, an intermediate layer, and an outer layer. The mass ratios of the rust-preventive masterbatch to linear low-density polyethylene in the inner, intermediate, and outer layers are 1:1.2, 1:2.5, and 1:4.5, respectively. The blown film die temperature is 170℃, the blow-up ratio is 3, and the total film thickness is 80μm.

[0052] Example 3: This example differs from Example 1 above in that: A novel composite vapor phase rust inhibitor film comprises the following raw materials in parts by weight: 20 parts halloysite nanotubes, 15 parts phytic acid, 5 parts benzotriazole, 3 parts ammonium molybdate, 1 part epoxidized soybean oil, 4 parts polyethylene grafted with maleic anhydride, 70 parts linear low-density polyethylene, and 8 parts low-density polyethylene.

[0053] Phytic acid is a 45% (w / w) aqueous solution of phytic acid.

[0054] Halloysite nanotubes have a diameter of 15 nm and a length of 0.5 μm.

[0055] The grafting rate of polyethylene grafted with maleic anhydride was 0.8%.

[0056] It also includes 1 part dispersant and 0.1 part antioxidant.

[0057] A method for manufacturing a novel composite vapor phase rust inhibitor film, applicable to the aforementioned novel composite vapor phase rust inhibitor film, includes the following steps: S1. After acid activation, halloysite nanotubes are subjected to the following steps: inner layer phytic acid loading, intermediate heat treatment fixation, outer layer benzotriazole and ammonium molybdate loading, port epoxidized soybean oil crosslinking sealing, and outer surface polyethylene grafting with maleic anhydride to obtain composite corrosion inhibitor filler. The acid activation process involved adding halloysite nanotubes to a 1.5 mol / L hydrochloric acid solution, stirring at 68°C for 2.5 hours, washing until the pH reached 6, and then drying. The inner phytic acid loading process involved immersing the acid-activated halloysite nanotubes in a phytic acid aqueous solution under a vacuum of -0.095 MPa for 3.5 hours, followed by vacuum drying at 48°C. The intermediate heat treatment fixation process involved heat treatment at 79°C for 2 hours. The outer benzotriazole and ammonium molybdate loading process involved immersing the nanotubes in an anhydrous ethanol solution of benzotriazole and ammonium molybdate under a vacuum of -0.095 MPa for 2.5 hours, followed by vacuum drying at 43°C. The cross-linking and sealing of the port with epoxidized soybean oil was carried out by dispersing the loaded halloysite nanotubes in anhydrous ethanol to prepare a suspension with a mass fraction of 5%, adding anhydrous ethanol dilute solution of epoxidized soybean oil dropwise at a mass-volume ratio of 1g:9mL for 30 minutes, then heating to 48℃ and reacting for 1 hour, adding 0.3% by weight of triethylamine of epoxidized soybean oil and continuing the reaction for 1.5 hours, filtering and washing, and then vacuum drying at 43℃. The outer surface of polyethylene grafted with maleic anhydride was prepared by reacting sealed halloysite nanotubes with polyethylene grafted with maleic anhydride in toluene under reflux at 78°C for 1.5 hours, with the mass fraction of the polyethylene-grafted maleic anhydride toluene solution being 2%. After the reaction, the mixture was filtered, washed successively with hot toluene and anhydrous ethanol, and then vacuum dried at 58°C.

[0058] S2. The composite corrosion inhibitor filler is blended with linear low-density polyethylene, low-density polyethylene, dispersant and antioxidant and granulated to obtain rust-preventive masterbatch. The twin-screw extruder used for granulation operates at a temperature of 145℃ and a screw speed of 180rpm.

[0059] S3. The rust-preventive masterbatch is co-extruded and blown into a film to obtain a novel composite vapor phase rust-preventive film.

[0060] The co-extruded blown film includes an inner layer, an intermediate layer, and an outer layer. The dilution mass ratios of the rust-preventive masterbatch to linear low-density polyethylene in the inner, intermediate, and outer layers are 1:0.8, 1:1.5, and 1:3.5, respectively. The blown film die temperature is 155℃, the blow-up ratio is 2.5, and the total film thickness is 50μm.

[0061] Comparative Example 1: A vapor phase rust inhibitor film comprising the following raw materials in parts by weight: 85 parts of low-density polyethylene, 10 parts of linear low-density polyethylene, 3 parts of sodium nitrite, 2 parts of sodium benzoate, 2 parts of dicyclohexyl octanoate, 1 part of dioctyl phthalate, and 5 parts of silica.

[0062] A method for preparing a vapor phase rust inhibitor film includes the following steps: The above raw materials are added to a high-speed mixer and premixed at 40°C for 10 minutes. The premixed material is then melt-granulated at 160°C using a twin-screw extruder to obtain rust-preventive masterbatch. The rust-preventive masterbatch was blown into shape at 165°C using a single-layer blown film machine with a blow-up ratio of 2.5 to obtain a vapor phase rust-preventive film with a thickness of 65μm.

[0063] Comparative Example 2: This comparative example differs from Example 1 above in that: In step S1, after the outer layer of benzotriazole and ammonium molybdate is loaded, the port of the non-epoxy soybean oil is not cross-linked and sealed, and the outer surface is directly grafted with maleic anhydride onto polyethylene.

[0064] Comparative Example 3: This comparative example differs from Example 1 above in that: Without polyethylene grafting maleic anhydride, in step S1, after completing the epoxy soybean oil crosslinking seal at the port, the outer surface is not grafted with polyethylene maleic anhydride, and the sealed composite corrosion inhibitor filler is directly used in step S2.

[0065] Comparative Example 4: This comparative example differs from Example 1 above in that: In step S1, after the inner phytic acid loading is completed, no intermediate heat treatment is performed for fixation, and the outer benzotriazole and ammonium molybdate loading is performed directly.

[0066] Comparative Example 5: This comparative example differs from Example 1 above in that: The solution containing benzotriazole and ammonium molybdate is free of benzotriazole and ammonium molybdate in step S1, meaning that only anhydrous ethanol is used as the impregnation solvent for blank loading.

[0067] Comparative Example 6: This comparative example differs from Example 1 above in that: Halloysite nanotubes comprise 10 parts, and phytic acid comprises 10 parts.

[0068] Comparative Example 7: This comparative example differs from Example 1 above in that: In step S3, the mass ratio of the rust-preventive masterbatch to linear low-density polyethylene for the inner, middle, and outer layers is 1:2.

[0069] Performance testing: Release rate synchronicity test: The vapor phase rust inhibitor films prepared in Examples 1-3 and Comparative Examples 1-7 were cut into 10cm×10cm samples and placed in a 40℃ constant temperature oven. Samples were taken on the 30th, 90th and 180th days, respectively. The contents of residual phytic acid, benzotriazole and ammonium molybdate in the film were determined by gas chromatography-mass spectrometry, and the remaining percentage of each component relative to the initial content was calculated. The range of the remaining percentages of the three components was used as the release rate synchronicity index. The smaller the range, the more synchronized the release. Neutral salt spray test: The neutral salt spray test was conducted according to GB / T 10125-2021 standard, with a test temperature of 35℃ and a sodium chloride solution concentration of 5%. Q235 carbon steel plate, T2 copper plate and 6061 aluminum alloy plate were used to simulate cast iron or steel parts, copper electrical components and aluminum alloy structural parts commonly used in automobiles and industrial machinery equipment, respectively. Three parallel samples were tested for each metal. The time when the first corrosion point appeared on the sample surface was recorded and the average value was taken as the salt spray resistance time. Water vapor transmission rate test: The water vapor transmission rate of the film was determined by cup method according to GB / T 1037-1988 standard, with a test temperature of 38℃ and a relative humidity of 90%. Mechanical property testing: The longitudinal tensile strength and elongation at break of the film were determined using a universal testing machine according to GB / T 1040.3-2006 standard, with a tensile speed of 200 mm / min. Surface morphology observation: The film sample was accelerated aged in a 60℃ constant temperature oven for 7 days. The presence or absence of white precipitates on the film surface was observed with the naked eye and divided into three levels: no visible precipitates, slight white bloom, and obvious white bloom. The test results are shown in Table 1.

[0070] Table 1: Performance test results of Examples 1-3 and Comparative Examples 1-7 As can be seen from Examples 1 to 3 and Comparative Examples 1 to 7, and Table 1, the axial partitioned loading of halloysite nanotubes, intermediate heat treatment fixation, end epoxy soybean oil crosslinking sealing, outer surface polyethylene grafting with maleic anhydride grafting, and multilayer co-extrusion gradient distribution achieve the synchronous release of multi-component corrosion inhibitors throughout the entire service life of the film, while simultaneously taking into account balanced protection against multiple metals, water vapor barrier, mechanical reinforcement, and surface anti-precipitation performance.

[0071] As can be seen from Example 1 and Comparative Example 2, and Table 1, the port-side epoxy soybean oil crosslinking sealing layer can control the release rate of corrosion inhibitors and achieve simultaneous release of multiple components. The semi-permeable network formed at the nanotube port can inhibit the rapid escape of highly volatile components, allowing corrosion inhibitor components with different volatilization rates to diffuse at similar rates through the same nanotube cavity. When this sealing layer is missing, components such as benzotriazole will be released in large quantities prematurely, resulting in a decrease in release synchronicity and thus affecting the balanced protection capability against multiple metals.

[0072] As can be seen from Example 1 and Comparative Example 3 and Table 1, the grafting of maleic anhydride onto the outer surface of polyethylene can improve the interfacial compatibility between the composite filler and the polyethylene matrix. The outer surface forms polyethylene segments that are highly compatible with the matrix resin, which is beneficial for the uniform dispersion of the filler in the resin matrix. When this grafting layer is missing, the interfacial bonding force between the filler and the matrix is ​​weakened, and the mechanical properties and barrier properties of the film are reduced.

[0073] As can be seen from Example 1 and Comparative Example 4, and Table 1, the intermediate heat treatment fixation after inner layer phytic acid loading can maintain the axial partition structure, causing phytic acid molecules to cross-link and polymerize, forming a network structure insoluble in anhydrous ethanol, preventing phytic acid from being washed away during outer layer loading. When this fixation step is missing, the inner and outer corrosion inhibitors mix, destroying the original design of nanotube axial partition loading and weakening the regulatory effect of confined diffusion on the synchronous release of multiple components.

[0074] As can be seen from Example 1 and Comparative Example 5, and Table 1, the loading of benzotriazole and ammonium molybdate in the outer layer can achieve protection for copper and aluminum alloys. Benzotriazole has a specific adsorption capacity for copper surfaces, and ammonium molybdate can form an oxide passivation film on iron and aluminum surfaces. When the outer layer immersion solution does not contain the above-mentioned corrosion inhibitors, the protective ability of the film for copper and aluminum is significantly reduced. At the same time, due to the lack of high-volatility components to regulate the release flux, the overall release kinetics of the system change, further affecting the release synchronicity.

[0075] As can be seen from Example 1 and Comparative Example 6, and Table 1, halloysite nanotubes can affect the mechanical properties of the film and the loading of the corrosion inhibitor. Halloysite nanotubes form a reinforcing network in the film as a one-dimensional nanofiller, and at the same time provide loading space as a storage container for the corrosion inhibitor. When the amount of nanotubes is insufficient, the total loading of the corrosion inhibitor decreases, the mechanical reinforcing effect of the nanotubes weakens, and the tensile strength of the film decreases.

[0076] Based on Example 1 and Comparative Example 7, and referring to Table 1, it can be seen that the gradient distribution structure of high concentration in the inner layer and low concentration in the outer layer of the multilayer co-extruded blown film is beneficial for the directional release of the corrosion inhibitor to the metal surface. The higher VCI concentration in the inner layer ensures sufficient effective concentration in the packaging space near the metal surface, while the lower VCI concentration in the outer layer reduces ineffective volatilization into the external environment. When the concentrations of the three layers are the same, the difference in release flux of the corrosion inhibitor in different directions decreases, and some corrosion inhibitor diffuses out of the film and is lost, reducing the utilization efficiency of the corrosion inhibitor.

[0077] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A novel composite vapor phase rust inhibitor film, characterized in that, The raw materials include the following parts by weight: halloysite nanotubes 20-30 parts, phytic acid 15-20 parts, benzotriazole 5-8 parts, ammonium molybdate 3-5 parts, epoxidized soybean oil 1-3 parts, polyethylene grafted with maleic anhydride 4-6 parts, linear low-density polyethylene 70-80 parts, and low-density polyethylene 8-12 parts.

2. The novel composite vapor phase rust inhibitor film according to claim 1, characterized in that: The phytic acid is an aqueous solution of phytic acid with a mass fraction of 45-55%.

3. The novel composite vapor phase rust inhibitor film according to claim 1, characterized in that: The halloysite nanotubes have a diameter of 15-30 nm and a length of 0.5-1.5 μm.

4. The novel composite vapor phase rust inhibitor film according to claim 1, characterized in that: The grafting rate of the polyethylene grafted with maleic anhydride is 0.8-1.2%.

5. The novel composite vapor phase rust inhibitor film according to claim 1, characterized in that: It also includes 1-2 parts of dispersant and 0.1-0.5 parts of antioxidant.

6. A method for manufacturing a novel composite vapor phase rust inhibitor film, characterized in that: The novel composite vapor phase rust inhibitor film according to any one of claims 1-5 comprises the following steps: S1. After acid activation, halloysite nanotubes are subjected to the following steps: inner layer phytic acid loading, intermediate heat treatment fixation, outer layer benzotriazole and ammonium molybdate loading, port epoxidized soybean oil crosslinking sealing, and outer surface polyethylene grafting with maleic anhydride to obtain composite corrosion inhibitor filler. S2. The composite corrosion inhibitor filler is blended and granulated with linear low-density polyethylene, low-density polyethylene, dispersant and antioxidant to obtain rust-preventive masterbatch. S3. The rust-preventive masterbatch is co-extruded and blown into a film to obtain a novel composite vapor phase rust-preventive film.

7. The method for manufacturing a novel composite vapor phase rust inhibitor film according to claim 6, characterized in that: In step S1, the acid activation involves adding halloysite nanotubes to a 1.5 mol / L hydrochloric acid solution, stirring and activating at 68-72°C for 2.5-3.5 hours, washing until the pH reaches 6-7, and then drying. The inner phytic acid loading involves immersing the acid-activated halloysite nanotubes in a phytic acid aqueous solution under a vacuum of -0.095 to -0.098 MPa for 3.5-4.5 hours, and then vacuum drying at 48-52°C. The intermediate heat treatment fixation involves heat treatment at 79-81°C for 2 hours. The outer benzotriazole and ammonium molybdate loading involves immersing the outer benzotriazole and ammonium molybdate in an anhydrous ethanol solution under a vacuum of -0.095 to -0.098 MPa for 2.5-3.5 hours, and then vacuum drying at 43-47°C.

8. The method for manufacturing a novel composite vapor phase rust inhibitor film according to claim 6, characterized in that: In step S1, the cross-linking and sealing of the port with epoxidized soybean oil involves dispersing the loaded halloysite nanotubes in anhydrous ethanol to prepare a suspension with a mass fraction of 5-10%, then adding a dilute solution of epoxidized soybean oil in anhydrous ethanol at a mass-to-volume ratio of 1g:9-11mL over a period of 30-60 minutes. The mixture is then heated to 48-52℃ and reacted for 1-1.5 hours. Triethylamine at a weight of 0.3-0.6% of the epoxidized soybean oil is added, and the reaction continues for another 1.5-2.5 hours. After filtration and washing, the mixture is vacuum dried at 43-47℃.

9. The method for manufacturing a novel composite vapor phase rust inhibitor film according to claim 6, characterized in that: In step S1, the outer surface polyethylene grafted with maleic anhydride is prepared by reacting the sealed halloysite nanotubes with polyethylene grafted with maleic anhydride in toluene under reflux at 78-82°C for 1.5-2.5 hours, and the mass fraction of the toluene solution of polyethylene grafted with maleic anhydride is 2-3%. After the reaction, the mixture is filtered, washed successively with hot toluene and anhydrous ethanol, and then vacuum dried at 58-62°C.

10. The method for manufacturing a novel composite vapor phase rust inhibitor film according to claim 6, characterized in that: In step S2, the temperature of the twin-screw extruder used for granulation is 145-160℃ and the screw speed is 180-220rpm; In step S3, the co-extruded blown film includes an inner layer, an intermediate layer, and an outer layer, and the dilution mass ratios of the rust-preventive masterbatch of the inner layer, the intermediate layer, and the outer layer to linear low-density polyethylene are 1:0.8-1.2, 1:1.5-2.5, and 1:3.5-4.5, respectively. The blown film die temperature is 155-170℃, the blow-up ratio is 2.5-3, and the total film thickness is 50-80μm.

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