A label with visible indication of VCI concentration, and a preparation method and gas-phase rust-proof paper thereof

Abstract

The application relates to the cross field of functional packaging materials and sensing technology, and specifically discloses a label with a VCI concentration visual indication function, a preparation method of the label and a gas-phase rust-preventing paper. The label is a multilayer composite structure, and sequentially comprises, from top to bottom, a transparent protective layer, a fluorescent indication function layer, a high-air-permeability hydrophobic isolation layer, a pressure-sensitive adhesive layer and release paper; the fluorescent indication function layer comprises a mesoporous silica composite loaded with pyrene dye; and the high-air-permeability hydrophobic isolation layer is an expanded polytetrafluoroethylene film. The label can specifically and reversibly correspond to the change of the concentration of a benzoic acid VCI gas, and can provide intuitive visual indication through the change of the fluorescence intensity, so that nondestructive and real-time monitoring of the state of the rust-preventing agent in the package is realized.

Description

Technical Field

[0001] This application relates to the intersection of functional packaging materials and sensing technology, and more specifically, it relates to a label with visual indication of VCI concentration, its preparation method, and vapor phase rust-preventing paper. Background Technology

[0002] Vapor phase corrosion inhibitor (VCI) paper, as an important means of preventing atmospheric corrosion of metals, has attracted much attention. VCI paper continuously releases vapor-phase corrosion inhibitor molecules in a closed environment, forming a protective film on the metal surface. This is crucial for protecting metal products and reducing economic losses caused by corrosion. With the widespread application of metal products in various industries, the requirements for the protective effect of VCI paper are becoming increasingly stringent. Its protective effect directly affects the quality and service life of metal products, thus possessing undeniable value in industrial production, transportation, and storage.

[0003] The protective effect of vapor phase corrosion inhibitor (VCI) paper directly depends on whether a sufficient VCI gas concentration can be maintained within the sealed packaging space. Currently, several methods are commonly used to assess the protective status within a sealed packaging space. Some people replace the VCI paper based on the "shelf life" indicated on the product label, assuming that the rust-preventive function is normal within this period. Others only open the packaging for inspection when signs of rust are noticed on the metal. Additionally, in a few cases, an independent humidity indicator is used to infer the rust-preventive effect based on the humidity level inside the packaging, believing that humidity and the rust-preventive ability of VCI paper are related.

[0004] However, existing methods have significant drawbacks. Replacing vapor phase corrosion inhibitor paper based on its "use period" is unscientific and cannot adapt to situations where the vapor phase corrosion inhibitor is abnormally consumed due to poor packaging sealing or changes in environmental conditions. Waiting until the metal rusts before inspection results in damage, failing to promptly guarantee the quality of metal products. Relying on humidity monitoring to judge rust prevention effectiveness also carries a high possibility of misjudgment, as humidity is not a direct factor determining rust prevention effectiveness; the actual concentration of the vapor phase corrosion inhibitor is crucial. Therefore, a technology that can directly, non-destructively, and in real-time monitor the effective concentration of vapor phase corrosion inhibitors within the packaging is currently lacking. Summary of the Invention

[0005] To address the aforementioned technical problems, this application provides a label with a visual indication function for VCI concentration, its preparation method, and a vapor phase rust-preventing paper. This label can specifically and reversibly respond to changes in the concentration of benzoic acid-based VCI gas, and provide an intuitive visual indication through changes in fluorescence intensity, thereby achieving non-destructive, real-time monitoring of the rust-preventing agent status inside the packaging.

[0006] Firstly, this application provides a label with a visual indication function for VCI concentration, which adopts the following technical solution:

[0007] A label with a visual indication function of VCI concentration is provided. The label has a multi-layer composite structure, which includes, from top to bottom, a transparent protective layer, a fluorescent indication functional layer, a highly breathable and hydrophobic isolation layer, a pressure-sensitive adhesive layer, and a release paper. The fluorescent indication functional layer includes a mesoporous silica composite loaded with pyrene dye. The highly breathable and hydrophobic isolation layer is an expanded polytetrafluoroethylene film.

[0008] By adopting the above technical solution, this application can utilize the mesoporous silica composite loaded with pyrene dye in the fluorescent indicator functional layer to specifically and reversibly respond to changes in the concentration of benzoic acid VCI gas. By observing changes in fluorescence intensity, the real-time status of the VCI concentration inside the packaging can be determined intuitively and non-destructively, achieving non-destructive and real-time monitoring of the status of the rust inhibitor inside the packaging. It also features fast response speed, high sensitivity, good reversibility, and strong resistance to moisture interference. At the same time, the expanded polytetrafluoroethylene film can block the migration of liquid water, ions, and solid functional materials, thereby ensuring that the label components will never contaminate or corrode the packaged metal workpiece, achieving intrinsic safety.

[0009] Preferably, in the mesoporous silica composite loaded with pyrene dye, the loading amount of pyrene dye is 1-5% of the mass of the mesoporous silica.

[0010] By adopting the above technical solution, this application controls the loading of pyrene dye to 1-5% of the mass of mesoporous silica, which enables the mesoporous silica to better interact with benzoic acid VCI gas molecules after loading with pyrene dye. This ensures that when benzoic acid VCI gas diffuses through the expanded polytetrafluoroethylene film to the fluorescent indicator functional layer in the sealed packaging, the fluorescence intensity of the pyrene dye can be reversibly quenched, thereby achieving effective monitoring of VCI concentration in the packaging.

[0011] If the pyrene content is too low, the fluorescence change will be insignificant when the fluorescent indicator layer interacts with benzoic acid-based VCI gas molecules, making it difficult to accurately determine changes in VCI concentration within the packaging and reducing the label's sensitivity and response speed. If the pyrene content is too high, excessive pyrene dye will accumulate on the surface of mesoporous silica, affecting its effective contact with VCI gas molecules, degrading the stability of the fluorescent indicator layer, reducing reversibility, and increasing costs.

[0012] Preferably, the specific surface area of ​​the mesoporous silicate is not less than 800 m². 2 / g, with a pore size of 2-5nm.

[0013] By adopting the above technical solution, the high specific surface area and ordered nanopores of the mesoporous silica in this application greatly increase the sensing interface, which can efficiently enrich the target gas molecules and promote their interaction with pyrene dye molecules, thereby achieving rapid response and high sensitivity. This allows the label to dynamically respond to changes in VCI concentration based on a reversible physical adsorption / desorption process, truly reflecting the real-time state changes inside the packaging.

[0014] Preferably, by weight, the raw materials used in the fluorescent indicator functional layer include: 5-15 parts of a mesoporous silica composite loaded with pyrene dye, 15-30 parts of a breathable polymer matrix, and 55-80 parts of a dispersing solvent.

[0015] Preferably, the breathable polymer matrix is ​​an organosilicon resin.

[0016] By adopting the above technical solution, this application uses a mixture of a mesoporous silica composite loaded with pyrene dye, a breathable polymer matrix, and a dispersing solvent in a certain ratio to ensure that the proportions of each component in the fluorescent indicator functional layer are appropriate, so that the mesoporous silica composite loaded with pyrene dye is uniformly dispersed in the breathable polymer matrix. This ensures that the functional layer interacts efficiently with benzoic acid VCI gas molecules, thereby achieving accurate, sensitive, and reversible fluorescent response indication of the VCI concentration in the packaging.

[0017] Preferably, the transparent protective layer is a polyethylene terephthalate film or a polycarbonate film with a thickness of 10-50 μm.

[0018] By adopting the above technical solution, this application sets the transparent protective layer as a polyethylene terephthalate film or a polycarbonate film with a thickness of 10-50 μm, which can protect the fluorescent indicator functional layer, etc., while ensuring a certain degree of light transmittance, so as to facilitate the observation of the fluorescence intensity change of the fluorescent indicator functional layer by ultraviolet light irradiation, so as to intuitively and non-destructively determine the real-time status of VCI concentration inside the packaging.

[0019] Preferably, the expanded polytetrafluoroethylene film has a thickness of 20-100 μm and a porosity greater than 70%.

[0020] By adopting the above technical solution, this application sets the thickness of the expanded polytetrafluoroethylene film to 20-100μm and the porosity to be greater than 70%. This ensures that VCI gas can diffuse smoothly through the film to the fluorescent indicator functional layer, enabling the label to respond normally to changes in VCI concentration. At the same time, its high permeability and hydrophobic properties can be used to block the migration of liquid water, ions and solid functional materials, ensuring that the indicator components will not contaminate or corrode the packaged metal workpiece, thus achieving intrinsic safety.

[0021] Secondly, this application provides a method for preparing a label with a visual indication function of VCI concentration, which adopts the following technical solution:

[0022] A method for preparing a label with visual indication of VCI concentration includes the following steps:

[0023] S1. Preparation of coating solution: The mesoporous silica composite loaded with pyrene dye is mixed with a breathable polymer matrix and solvent and dispersed evenly to prepare a fluorescent indicator functional layer coating solution.

[0024] S2. Coating and curing: The fluorescent indicator functional layer coating liquid is coated onto the release film, and then heated and dried to form a fluorescent indicator functional layer film;

[0025] S3. Lamination: The film used for the transparent protective layer, the film used for the fluorescent indicator functional layer, and the film used for the highly breathable and hydrophobic isolation layer are laminated sequentially.

[0026] S4. Post-processing: A pressure-sensitive adhesive is coated on one side of the expanded polytetrafluoroethylene film of the composite obtained in step S3 to form a pressure-sensitive adhesive layer. Then, release paper is covered and the label is obtained after die-cutting.

[0027] Preferably, the mesoporous silica composite loaded with pyrene dye is prepared by the following method:

[0028] Pyrene dye was dissolved in an organic solvent, and then mesoporous silica was added for ultrasonic dispersion and stirring. After drying, a mesoporous silica composite loaded with pyrene dye was obtained.

[0029] Thirdly, the vapor phase corrosion inhibitor paper provided in this application adopts the following technical solution:

[0030] A vapor phase corrosion inhibitor paper includes a vapor phase corrosion inhibitor paper substrate and a label with a visual indication function of VCI concentration, wherein the label is adhered to the surface of the vapor phase corrosion inhibitor paper substrate through its pressure-sensitive adhesive layer.

[0031] By adopting the above technical solution, this application first attaches a label with VCI concentration visual indication function to the surface of a vapor phase corrosion inhibitor paper substrate through its pressure-sensitive adhesive layer to obtain vapor phase corrosion inhibitor paper. Then, the metal workpiece to be protected is wrapped with the vapor phase corrosion inhibitor paper and placed in a sealed environment such as a transparent PE bag. In this sealed environment, the vapor phase corrosion inhibitor paper continuously releases benzoic acid-based VCI gas to protect the metal workpiece. Benzoic acid-based VCI gas molecules in the sealed environment can diffuse through the micropores of the expanded polytetrafluoroethylene (ePTFE) film into the fluorescent indicator functional layer. In the functional layer, pyrene dye molecules loaded in the high specific surface area channels of mesoporous silica undergo intermolecular interactions such as π-π stacking with the diffused benzoic acid molecules, resulting in a reversible decrease (quenching) in the fluorescence intensity of pyrene. The higher the VCI concentration, the more significant the fluorescence quenching. Users can irradiate the label with a specific wavelength (such as 365nm) of ultraviolet light source and directly determine the relative level and dynamic change process of VCI concentration in the closed environment by observing the changes in fluorescence intensity with the naked eye or detecting the changes with instruments. This enables non-destructive, real-time monitoring of the state of the rust inhibitor inside the sealed packaging.

[0032] In summary, this application has the following beneficial technical effects:

[0033] 1. This application can directly monitor the core parameter of VCI concentration inside a closed package and achieve dynamic response based on a reversible physical adsorption / desorption process, which can truly reflect the real-time state changes inside the closed package;

[0034] 2. The high specific surface area and ordered nanopores of the mesoporous silica in this application greatly increase the sensing interface, which can efficiently enrich target gas molecules and promote their interaction with pyrene dye molecules, thereby achieving rapid response and high sensitivity.

[0035] 3. This application utilizes the specific response of pyrene dye to the aromatic ring structure of benzoic acid and the barrier of ePTFE film to liquid water, making the label insensitive to changes in ambient humidity and effectively avoiding the false alarm problem of traditional humidity indicators;

[0036] 4. This application uses ePTFE film as an isolation layer, which greatly reduces the risk of indicator contact with metal workpieces, and the die-cut label format facilitates integration with existing rust-proof paper production lines, enabling industrial application;

[0037] 5. This application only requires ultraviolet light irradiation to complete the inspection, which is convenient to operate and achieves true non-destructive and rapid condition assessment, greatly improving the efficiency of inventory management and quality traceability. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the layered structure of the label with VCI concentration visual indication function in this application. Detailed Implementation

[0039] The following is in conjunction with the appendix Figure 1 This application will be described in further detail.

[0040] Reference Figure 1 The present application discloses a label with a visual indication function of VCI concentration, which includes, from top to bottom, a transparent protective layer, a fluorescent indication functional layer, a highly breathable and hydrophobic isolation layer, a pressure-sensitive adhesive layer, and a release paper.

[0041] The raw materials used in the fluorescent indicator functional layer include: 5-15 parts of a mesoporous silica composite loaded with pyrene dye, 15-30 parts of a breathable polymer matrix, and 55-80 parts of a dispersing solvent.

[0042] The mesoporous silica composite loaded with pyrene dye was prepared by the following method:

[0043] Pyrene dye was dissolved in an organic solvent, then mesoporous silica was added and ultrasonically dispersed and stirred. After drying, a mesoporous silica composite loaded with pyrene dye was obtained. The loading amount of pyrene dye was 1-5% of the mass of the mesoporous silica, and the specific surface area of ​​the mesoporous silica was not less than 800 m². 2 / g, with a pore size of 2-5nm.

[0044] The breathable polymer matrix is ​​an organosilicon resin.

[0045] The transparent protective layer is a polyethylene terephthalate film or a polycarbonate film with a thickness of 10-50 μm.

[0046] The expanded polytetrafluoroethylene film has a thickness of 20-100 μm and a porosity greater than 70%.

[0047] The preparation method of the above-mentioned label with VCI concentration visual indication function includes the following steps:

[0048] S1. Preparation of coating solution: The mesoporous silica composite loaded with pyrene dye is mixed with a breathable polymer matrix and solvent and dispersed evenly to prepare a fluorescent indicator functional layer coating solution.

[0049] S2. Coating and curing: The fluorescent indicator functional layer coating liquid is coated onto the release film, and then heated and dried to form a fluorescent indicator functional layer film;

[0050] S3. Lamination: The film used for the transparent protective layer, the film used for the fluorescent indicator functional layer, and the film used for the highly breathable and hydrophobic isolation layer are laminated sequentially.

[0051] S4. Post-processing: A pressure-sensitive adhesive is coated on one side of the expanded polytetrafluoroethylene film of the composite obtained in step S3 to form a pressure-sensitive adhesive layer. Then, release paper is covered and the label is obtained after die-cutting.

[0052] After the label is bonded to the surface of the vapor phase rust inhibitor paper substrate through its pressure-sensitive adhesive layer to obtain the vapor phase rust inhibitor paper, the metal workpiece to be protected is wrapped with the vapor phase rust inhibitor paper and placed in a sealed environment such as a transparent PE bag. The relative level and dynamic change process of the VCI concentration in the sealed environment can be directly determined by visual observation or instrument detection of the change in fluorescence intensity. This achieves non-destructive, real-time monitoring of the state of the rust inhibitor inside the sealed packaging.

[0053] The applicant further verified the effectiveness of this application using the following examples and comparative examples. Unless otherwise specified, the raw materials used in this application can be purchased through commercial channels.

[0054] <Example 1>

[0055] The raw material components used in the fluorescent indicator functional layer coating solution include: 0.3 kg of pyrene dye (purity ≥ 98%), and mesoporous silica (BET ≈ 1000 m). 2 / g, pore size≈3.4nm) 10kg, silicone resin (room temperature curing type, viscosity≈5000mPa·s, Dow Corning SYLGARD® 184 or Wacker ELASTOSIL® RT 601 / 602 series can be selected) 25kg, ethyl acetate 64.7kg;

[0056] A method for preparing a label with visual indication of VCI concentration includes the following steps:

[0057] S1. Preparation of coating solution: First, dissolve 0.3 kg of pyrene dye in part of ethyl acetate, then add mesoporous silica powder, and stir for 2 h under ultrasonic assistance to allow the pyrene dye molecules to be fully adsorbed and loaded onto the pores and surface of the mesoporous silica, thus obtaining a mesoporous silica composite loaded with pyrene dye. Then add organosilicon resin and the remaining ethyl acetate, and continue high-speed mechanical stirring for 1 h until the mixture is uniform, thus obtaining a stable fluorescent indicator functional layer coating solution.

[0058] S2. Coating and curing: The fluorescent indicator functional layer coating liquid is coated onto the PET release film using a wire bar coater. The wet film thickness is set to 150 μm. The coated film is then placed in an 80°C forced-air oven to dry for 15 min. After the solvent evaporates and the film is cured, a fluorescent indicator functional layer film with a thickness of about 20 ± 2 μm is obtained.

[0059] S3. Lamination: A 25μm transparent polycarbonate film is covered on top of the fluorescent indicator functional layer film obtained in step S2, and a 50μm ePTFE film is covered on the bottom of the fluorescent indicator functional layer film obtained in step S2. Then, hot-pressing is performed using a laminator at 100℃ and 0.4MPa pressure, with the lamination speed controlled at 3m / min.

[0060] S4. Post-processing: A layer of acrylic pressure-sensitive adhesive is uniformly coated on one side of the expanded polytetrafluoroethylene film of the composite obtained in step S3 to form a pressure-sensitive adhesive layer. Then, release paper is used for protection. Finally, a die-cutting machine is used to cut it into a 25mm×25mm square label.

[0061] When applying, peel off the release paper on the back of the die-cut label and attach it manually or using an automatic labeling machine to the edge of the commercially available sodium benzoate type vapor phase corrosion inhibitor paper to obtain vapor phase corrosion inhibitor paper with VCI concentration visual indication function.

[0062] <Example 2>

[0063] A method for preparing a label with a visual indication function of VCI concentration differs from Example 1 in that the raw material components used in the coating liquid for the fluorescent indicator functional layer include: 0.5 kg of pyrene dye (purity ≥98%) and mesoporous silica (BET≈1000m). 2 10 kg of silicone resin (room temperature curing type, viscosity ≈ 5000 mPa·s), 25 kg of ethyl acetate, and the rest were the same as in Example 1.

[0064] <Example 3>

[0065] A method for preparing a label with a visual indication function of VCI concentration differs from Example 1 in that the raw material components used in the coating liquid for the fluorescent indicator functional layer include: 0.1 kg of pyrene dye (purity ≥98%) and mesoporous silica (BET≈1000m). 2 10 kg of silicone resin (room temperature curing type, viscosity ≈ 5000 mPa·s), 25 kg of ethyl acetate, and the rest were the same as in Example 1.

[0066] <Comparative Example 1>

[0067] The difference from Example 1 is that the step of "covering a 50μm ePTFE film under the fluorescent indicator functional layer film obtained in step S2" in step S3 is removed. Instead, after the fluorescent indicator functional layer film is composited with the transparent polycarbonate film, an acrylic pressure-sensitive adhesive is directly and uniformly coated on the back of the fluorescent indicator functional layer film. The rest is the same as in Example 1.

[0068] <Comparative Example 2>

[0069] The difference from Example 1 is that the mesoporous silica in step S1 is replaced with an equal weight of ordinary precipitated silica (BET≈200m).2 / g, irregular pore structure), the rest is the same as in Example 1.

[0070] <Comparative Example 3>

[0071] The difference from Example 1 is that in step S1, the loading of pyrene dye is 0.5% of the mass of mesoporous silica, that is, the amount of pyrene dye used is 0.05 kg, and the rest is the same as in Example 1.

[0072] <Comparative Example 4>

[0073] The difference from Example 1 is that in step S1, the loading of pyrene dye is 8% of the mass of mesoporous silica, that is, the amount of pyrene dye used is 0.8 kg, and the rest is the same as in Example 1.

[0074] Performance Testing

[0075] The labels prepared in the above embodiments and comparative examples were subjected to relevant performance tests, and the results are shown in Table 1.

[0076] Relevant performance tests include: fluorescence responsiveness, reversibility, resistance to moisture interference, safety (metal contact corrosion), and high-temperature stability.

[0077] Fluorescence responsiveness: The tag was placed in a test chamber with an adjustable atmosphere. A high-concentration VCI environment was simulated by saturated benzoic acid vapor, and a low-concentration environment was simulated by introducing dry air. The fluorescence intensity change of the tag at a wavelength of 395 nm was monitored in real time using a fluorescence spectrophotometer. The time required for the fluorescence intensity to drop to 90% of the stable value (T90, characterizing the response rate) was recorded, and the maximum fluorescence quenching rate was calculated.

[0078] Reversibility: After completing the high-concentration response test, remove the benzoic acid source and purge the test chamber with dry air. Detect and record the proportion of fluorescence intensity that recovers to more than 90% of the initial value.

[0079] Resistance to moisture interference: The label was placed in a constant temperature and humidity chamber at 25℃ and 90% relative humidity (without VCI environment) for 24 hours, and the change rate of its fluorescence intensity was tested.

[0080] Safety (Metal-to-Metal Corrosion): The fluorescent indicator layer during the label manufacturing process was brought into close contact with polished and cleaned 20# carbon steel sheets and H62 brass sheets, and placed in an environment of 40℃ and 90%RH for 7 days. Afterward, the metal sheets were removed and the surface was observed for any rust or discoloration spots.

[0081] High temperature stability: The label was placed in a 60℃ oven for 48 hours for aging treatment. After being removed and cooled to room temperature, its fluorescence response performance was retested and compared with the data before aging. The performance retention rate after aging was recorded.

[0082] Table 1 Performance Test Results

[0083]

[0084] As shown in Table 1, the tags prepared in Examples 1-3 of this application all exhibit excellent overall performance. Specifically, the rapid response (1.5-3.2 h) and high fluorescence quenching (80-92%) are due to the efficient fixation of pyrene dye and the rapid adsorption and conduction of benzoic acid molecules by the ordered nanopores of mesoporous silica. Excellent reversibility demonstrates that its physical mechanism is suitable for dynamic monitoring. The isolating effect of the ePTFE film is crucial, ensuring signal stability (strong anti-interference) in high humidity environments and completely eliminating the risk of corrosion when in contact with metals.

[0085] Comparative Example 1 (without ePTFE membrane): Although the response speed and quenching rate were acceptable, the lack of a crucial moisture barrier layer allowed ambient moisture to directly affect the functional layer, causing drastic and uncontrollable changes in the fluorescence signal and complete failure of its resistance to moisture interference. More seriously, in high-temperature and high-humidity contact tests, organic components and potentially hygroscopic impurities in the functional layer migrated to the metal surface, triggering significant contact corrosion and demonstrating its safety failure.

[0086] Comparative Example 2 (Ordinary SiO2 support): Performance significantly decreased. The low specific surface area and disordered pore structure of ordinary silica cannot effectively load and disperse pyrene dyes, nor can it enrich VCI molecules, resulting in extremely slow response, weak signal changes, and an irreversible process. This demonstrates that the specific nanostructure of mesoporous silica is one of the key elements of this invention.

[0087] Comparative Example 3 (Pyrene dye loading too low): Performance decreased significantly, response was slow, fluorescence quenching rate was low, and reversibility was poor, indicating that the loading was too low and could not effectively respond to changes in VCI concentration.

[0088] Comparative Example 4 (excessive pyrene dye loading): Although the quenching rate was acceptable, the recovery rate decreased and the stability after aging was poor, indicating that excessive loading easily leads to the aggregation of pyrene molecules, affecting reversibility and long-term stability.

[0089] In summary, this application, through the synergistic innovation of a "pyrene dye / mesoporous silica" composite sensing material and an "ePTFE membrane safety isolation" structure, has successfully developed a reliable, safe, and practical VCI concentration visualization label. Integrating this label into vapor phase rust-preventing paper provides the industry with a direct, non-destructive, and real-time effective tool for monitoring the status of rust-preventive packaging, demonstrating significant application value.

[0090] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A label with a visual indication function for VCI concentration, characterized in that, The label has a multi-layer composite structure, which includes, from top to bottom, a transparent protective layer, a fluorescent indicator functional layer, a highly breathable and hydrophobic isolation layer, a pressure-sensitive adhesive layer, and a release paper; the fluorescent indicator functional layer includes a mesoporous silica composite loaded with pyrene dye; the highly breathable and hydrophobic isolation layer is an expanded polytetrafluoroethylene film.

2. A label with VCI concentration visual indication function according to claim 1, characterized in that, In the mesoporous silica composite loaded with pyrene dye, the loading amount of pyrene dye is 1-5% of the mass of the mesoporous silica.

3. A label with VCI concentration visual indication function according to claim 2, characterized in that, The specific surface area of ​​the mesoporous silicate is not less than 800 m². 2 / g, with a pore size of 2-5nm.

4. A label with VCI concentration visual indication function according to claim 1, characterized in that, By weight, the raw materials used in the fluorescent indicator functional layer include: 5-15 parts of a mesoporous silica composite loaded with pyrene dye, 15-30 parts of a breathable polymer matrix, and 55-80 parts of a dispersing solvent.

5. A label with VCI concentration visual indication function according to claim 4, characterized in that, The breathable polymer matrix is ​​an organosilicon resin.

6. A label with VCI concentration visual indication function according to claim 1, characterized in that, The transparent protective layer is a polyethylene terephthalate film or a polycarbonate film with a thickness of 10-50 μm.

7. A label with VCI concentration visual indication function according to claim 1, characterized in that, The expanded polytetrafluoroethylene film has a thickness of 20-100 μm and a porosity greater than 70%.

8. A method for preparing a label with VCI concentration visual indication function as described in any one of claims 1-7, characterized in that, Includes the following steps: S1. Preparation of coating solution: The mesoporous silica composite loaded with pyrene dye is mixed with a breathable polymer matrix and solvent and dispersed evenly to prepare a fluorescent indicator functional layer coating solution. S2. Coating and curing: The fluorescent indicator functional layer coating liquid is coated onto the release film, and then heated and dried to form a fluorescent indicator functional layer film; S3. Lamination: The film used for the transparent protective layer, the film used for the fluorescent indicator functional layer, and the film used for the highly breathable and hydrophobic isolation layer are laminated sequentially. S4. Post-processing: A pressure-sensitive adhesive is coated on one side of the expanded polytetrafluoroethylene film of the composite obtained in step S3 to form a pressure-sensitive adhesive layer. Then, release paper is covered and the label is obtained after die-cutting.

9. A method for preparing a label with a visual indication function of VCI concentration according to claim 8, characterized in that, The mesoporous silica composite loaded with pyrene dye was prepared by the following method: Pyrene dye was dissolved in an organic solvent, and then mesoporous silica was added for ultrasonic dispersion and stirring. After drying, a mesoporous silica composite loaded with pyrene dye was obtained.

10. A vapor phase corrosion inhibitor paper, characterized in that, The label comprises a vapor phase rust inhibitor paper substrate and a label with VCI concentration visual indication function as described in any one of claims 1-7, wherein the label is adhered to the surface of the vapor phase rust inhibitor paper substrate by means of its pressure-sensitive adhesive layer.

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