Vacuum bag film with air leakage self-early warning function and preparation method

Abstract

The invention relates to the field of wind power blade perfusion, and provides a vacuum bag film with an air leakage self-early warning function and a preparation method thereof.The vacuum bag film at least comprises an upper protective layer, a middle layer and a lower protective layer, microcapsules of a core-shell structure are dispersed in the middle layer, the core material of each microcapsule is a gas-sensitive color-changing material, and the lower protective layer is a hollow layer. The wall material of the microcapsule is a temperature response material, and the response temperature of the temperature response material is 45-55 DEG C. According to the vacuum bag film with the air leakage self-warning function, the microcapsule structure endows the vacuum bag film with excellent processing adaptability, so that the vacuum bag film can be randomly cut at normal temperature without damaging the integrity of a functional layer, and the vacuum bag film has long-acting storage stability; in actual use, heat release reaching 45-55 DEG C in the resin filling process is used as an activation signal, so that the microcapsule wall material is broken to release the core material; at the moment, if air leakage occurs, air can invade, and the color of the air-sensitive material is rapidly changed, so that in-situ, visual and accurate early warning of a leakage point is realized, and the scrap rate of the blade is effectively reduced.

Description

Technical Field

[0001] This invention relates to the field of wind turbine blade injection, and more specifically, to a vacuum bag membrane with a self-early warning function for air leakage and its preparation method. Background Technology

[0002] Vacuum-assisted resin infusion molding technology (vacuum infusion for short) is a low-cost, high-efficiency molding technology for high-performance composite materials using vacuum bag film with self-warning leakage function, widely used in the molding and manufacturing of wind turbine blades. Its significant feature is that vacuum bag film (flexible mold, disposable mold) and rigid mold are respectively set on the upper and lower sides of the product. Under the action of internal and external pressure difference, the vacuum bag film deforms and is compressed, resulting in a dense product with low porosity. The airtightness of the vacuum bag film is one of the key indicators for completing vacuum infusion. In actual production, due to the unavoidable presence of micropores inside the vacuum bag film, as the curing temperature rises, the micropores expand, allowing external gas to leak in, causing whitening defects in the product, or even scrapping it. Existing leak detection technologies focus on monitoring sound velocity, air pressure, and the flow of specific gases at the leak point, and there are also highly sensitive technologies such as helium mass spectrometry leak detection. However, for ultra-large blades, leaks are randomly distributed over 500m. 2 In the areas mentioned above, the equipment has a limited range of leak detection and is expensive, making it difficult to apply on a large scale.

[0003] The prior art patent CN201710233228.9 discloses a method for detecting leaks in multilayer vacuum bag films using an oxygen-sensitive substance. This method involves adding the oxygen-sensitive substance to the middle layer of the multilayer vacuum bag film while maintaining its unoxidized state. The multilayer vacuum bag film is then placed in air, and leaks are identified by color changes observed at these points. The oxygen-sensitive substance changes color upon contact with air, and this color change is visible to the naked eye. The multilayer vacuum bag film has at least three layers, and the middle layer refers to any one or more interlayers between the inner and outer surfaces of the vacuum bag film. While this patent can automatically detect the airtightness of the vacuum bag film based on changes in the external oxygen concentration, several technical challenges remain in its preparation, storage, and use.

[0004] 1. The sensitive materials are directly dispersed in the membrane layer, lacking a protective mechanism, making storage difficult. Maintaining oxygen-sensitive substances in an unoxidized state makes the preparation of vacuum bag membranes very challenging, which greatly increases the complexity of production equipment and manufacturing costs.

[0005] 2. Vacuum bag film itself cannot be flexibly cut, resulting in poor practicality: Once the vacuum bag film is cut, the oxygen-sensitive material at its edges immediately comes into contact with oxygen in the air and oxidizes and discolors. This discoloration starts from the cut edge and gradually penetrates and spreads into the interior of the film. This means that with each cut, not only does the cut portion become unusable, but the remaining large roll of material also becomes unusable due to the continuous penetration of the color. This severely limits its application in industrial scenarios that require cutting according to different workpiece sizes (such as the manufacturing of large blades), resulting in a huge waste of materials.

[0006] 3. In actual production, vacuum bag film leakage usually occurs during the heating stage. This technology is a passive and continuous monitoring method, which is prone to generating invalid alarms. It cannot distinguish the key time point when the leakage occurs, nor can it activate the monitoring function only when monitoring is most needed.

[0007] In view of this, the present invention is hereby proposed. Summary of the Invention

[0008] The purpose of this invention is to propose a vacuum bag membrane with a self-early warning function for leaks and its preparation method, so as to solve the problems of existing methods that use oxygen-sensitive materials to detect leaks in multi-layer vacuum bag membranes, such as the difficulty in storing oxygen-sensitive materials, the high difficulty in preparing vacuum bag membranes, and the inability to flexibly cut the vacuum bag membranes themselves, resulting in poor practicality.

[0009] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0010] A vacuum bag film with a self-prevention function for air leakage, the vacuum bag film comprising at least an upper protective layer, a middle layer, and a lower protective layer.

[0011] The intermediate layer contains core-shell structured microcapsules, the core material of which is a gas-sensitive color-changing material, and the wall material of which is a temperature-responsive material with a response temperature of 45~55℃.

[0012] Furthermore, the core material of the microcapsule is a nitrogen dioxide-sensitive system or an oxygen-sensitive system.

[0013] Furthermore, the core material of the microcapsule is a nitrogen dioxide sensitive system, the gas-sensitive color-changing material is 5,10,15,20-tetraphenylporphyrin, the temperature-responsive material is modified polyurea, and the substrate of the intermediate layer is ethylene-vinyl acetate copolymer.

[0014] Furthermore, the core material of the microcapsule is an oxygen-sensitive system, the gas-sensitive color-changing material is reduced methylene blue and glucose, the temperature-responsive material is a cross-linked polyurea / polyurethane shell, and the substrate of the intermediate layer is waterborne polyurethane or VAE emulsion.

[0015] Furthermore, the content of microcapsules in the intermediate layer is 15~35wt%.

[0016] Furthermore, the average particle size of the microcapsules is 9~11 μm.

[0017] Furthermore, the dry film thickness of the intermediate layer is 15~60um.

[0018] Furthermore, both the upper and lower protective layers are made of nylon 6.

[0019] A second aspect of the present invention provides a method for preparing a vacuum bag film with a self-prevention function for leaks, the method being used to prepare a vacuum bag film with a self-prevention function for leaks as described in any one of the present invention, the method comprising the following steps:

[0020] S1. Microcapsule preparation: Microcapsule powder is obtained by in-situ polymerization or interfacial polymerization of the oil phase and aqueous phase;

[0021] S2. Preparation of intermediate layer: Microcapsule powder is added to the substrate of intermediate layer, stirred and dispersed evenly to obtain an aqueous coating solution for coating. The solution is coated on the lower or upper protective layer at <40℃ and dried.

[0022] S3. Multilayer composite: The upper protective layer, middle layer and lower protective layer are composited using dry composite or solvent-free composite process. After completion, the composite is cured at a temperature of <42℃ to obtain a vacuum bag film with leakage self-warning function.

[0023] This invention proposes a vacuum bag film with a self-prevention function for leaks and its preparation method. Compared with the prior art, the vacuum bag film with a self-prevention function and its preparation method described in this invention have the following advantages:

[0024] 1. The present invention provides a vacuum bag membrane with a self-early warning function for air leakage and its preparation method. The temperature-responsive material completely encapsulates the gas-sensitive color-changing material, forming a protective layer for the gas-sensitive color-changing material, making the microcapsules easy to store. Furthermore, the vacuum bag membrane does not require an oxygen-free environment during preparation and can be prepared under conventional conditions, which greatly reduces the difficulty and cost of preparing the vacuum bag membrane.

[0025] 2. The vacuum bag membrane with leakage self-warning function and its preparation method described in this invention allow for arbitrary cutting and use, resulting in high practicality. Because the gas-sensitive material is protected by the microcapsule wall material, even if the microcapsules at the cut surface are exposed to air during cutting, the internal core material will not be oxidized. Only after reaching a specific temperature and the wall material ruptures will the core material be exposed and exhibit color-changing ability. This allows the vacuum bag membrane to be arbitrarily cut and spliced ​​according to the specific size and shape of workpieces such as blades, just like ordinary materials, greatly improving the practicality and convenience of the material and avoiding waste.

[0026] 3. The vacuum bag membrane with leakage self-early warning function and its preparation method described in this invention are specifically designed for leakage caused by temperature rise. The leak detection is intelligently triggered when the temperature is between 45 and 55°C, responding to real leakage risks and accurately aligning with process requirements: the design perfectly matches the curing exothermic curve of the epoxy resin system and automatically starts monitoring at the stage where problems are most likely to occur.

[0027] 4. The vacuum bag membrane with leakage self-early warning function and its preparation method described in this invention can significantly amplify (change color) the leakage signal in situ during the vacuum filling process through the vacuum bag membrane, and can be directly detected by the human eye, thereby enabling efficient detection of leakage and reducing leakage defects and blade scrapping.

[0028] 5. The vacuum bag membrane with self-early warning function and its preparation method described in this invention, compared with equipment-based leak detection methods, adopts an innovative material approach, eliminating the need for setting up detection equipment, and is unaffected by the random distribution and expansion of micropores over a large area of ​​more than 500㎡. It only changes color at the leak point, eliminating the need for manual handheld scanning, and the leak point can be instantly located by the naked eye; the investment cost is extremely low, and the detection effect is excellent.

[0029] 6. The vacuum bag film with leakage self-warning function and its preparation method described in this invention have strong anti-interference ability: the introduction of a temperature switch completely solves the problem of accidental color change of traditional color-changing films during storage and transportation. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the structure of a vacuum bag film with a self-early warning function for air leakage, as described in an embodiment of the present invention.

[0031] Figure 2 This is one of the flowcharts illustrating a method for preparing a vacuum bag film with a self-early warning function for air leakage, as described in an embodiment of the present invention.

[0032] Figure 3 This is a second schematic flowchart of a method for preparing a vacuum bag film with a self-early warning function for air leakage, as described in an embodiment of the present invention.

[0033] Explanation of reference numerals in the attached figures:

[0034] 11. Upper protective layer; 12. Middle layer; 13. Lower protective layer; 4. Microcapsule. Detailed Implementation

[0035] To make the technical means and objectives and effects of the present invention easier to understand, the embodiments of the present invention will be described in detail below with reference to specific illustrations.

[0036] It should be noted that all directional and positional terms used in this invention, such as "up," "down," "left," "right," "front," "back," "vertical," "horizontal," "inner," "outer," "top," "lower," "lateral," "longitudinal," and "center," are only used to explain the relative positional relationships and connections between components in a specific state (as shown in the accompanying drawings). They are merely for the convenience of describing the invention and do not require the invention to be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on the invention. Furthermore, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated.

[0037] In the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0038] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0039] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0040] Example 1

[0041] The prior art patent CN201710233228.9 discloses a method for detecting leaks in multilayer vacuum bag films using an oxygen-sensitive substance. This method involves adding the oxygen-sensitive substance to the middle layer of the multilayer vacuum bag film while maintaining its unoxidized state. The multilayer vacuum bag film is then placed in air, and leaks are identified by color changes observed at these points. The oxygen-sensitive substance changes color upon contact with air, and this color change is visible to the naked eye. The multilayer vacuum bag film has at least three layers, and the middle layer refers to any one or more interlayers between the inner and outer surfaces of the vacuum bag film. While this patent can automatically detect the airtightness of the vacuum bag film based on changes in the external oxygen concentration, several technical challenges remain in its preparation, storage, and use.

[0042] 1. The sensitive materials are directly dispersed in the membrane layer, lacking a protective mechanism, making storage difficult. Maintaining oxygen-sensitive substances in an unoxidized state makes the preparation of vacuum bag membranes very challenging, which greatly increases the complexity of production equipment and manufacturing costs.

[0043] 2. Vacuum bag film itself cannot be flexibly cut, resulting in poor practicality: Once the vacuum bag film is cut, the oxygen-sensitive material at its edges immediately comes into contact with oxygen in the air and oxidizes and discolors. This discoloration starts from the cut edge and gradually penetrates and spreads into the interior of the film. This means that with each cut, not only does the cut portion become unusable, but the remaining large roll of material also becomes unusable due to the continuous penetration of the color. This severely limits its application in industrial scenarios that require cutting according to different workpiece sizes (such as the manufacturing of large blades), resulting in a huge waste of materials.

[0044] 3. In actual production, vacuum bag film leakage usually occurs during the heating stage. This technology is a passive and continuous monitoring method; it cannot distinguish the key time point when leakage occurs, nor can it activate the monitoring function only when monitoring is most needed.

[0045] To solve the above-mentioned technical problems, in this embodiment, as follows: Figures 1-3 As shown, a vacuum bag membrane with a self-early warning function for air leakage is proposed. The vacuum bag membrane includes at least an upper protective layer 11, an intermediate layer 12 and a lower protective layer 13. Core-shell structured microcapsules 4 are dispersed in the intermediate layer 12. The core material of the microcapsules 4 is a gas-sensitive color-changing material, and the wall material of the microcapsules 4 is a temperature-responsive material with a response temperature of 45~55℃.

[0046] The vacuum bag film with leakage self-early warning function described in this embodiment has the following advantages:

[0047] First, the temperature-responsive material completely encapsulates the gas-sensitive color-changing material, forming a protective layer for the gas-sensitive color-changing material, making the microcapsule 4 easy to store; and the vacuum bag film does not require an oxygen-free environment during preparation, but can be prepared under normal conditions, which greatly reduces the difficulty of vacuum bag film preparation and reduces costs.

[0048] II. Vacuum bag film can be cut and used arbitrarily, offering high practicality: Because the gas-sensitive material is protected by the microcapsule 4 wall material, even if the microcapsule 4 at the cut surface is exposed to air during cutting, the internal core material will not be oxidized; only after reaching a specific temperature and the wall material ruptures will the core material be exposed and possess the ability to change color. This allows the vacuum bag film to be cut and spliced ​​arbitrarily according to the specific size and shape of workpieces such as blades, just like ordinary materials, greatly improving the practicality and convenience of the material and avoiding waste.

[0049] Third, specifically designed for leaks caused by temperature rise, it intelligently triggers leak detection when the temperature is between 45 and 55°C, responding to real leak risks and accurately aligning with process requirements: This design perfectly matches the actual physical phenomenon of leakage caused by orifice enlargement after temperature rise, making the sensitive period of monitoring completely synchronized with the high-incidence period of leaks.

[0050] This embodiment describes a vacuum bag membrane with a self-early warning function for leaks. The microcapsule structure gives the vacuum bag membrane excellent processing adaptability, allowing it to be arbitrarily cut at room temperature without damaging the integrity of the functional layers, and providing long-term storage stability. In practical use, this invention utilizes the exothermic reaction during resin infusion, reaching 45-55°C, as an activation signal to cause the microcapsule wall material to rupture and release the core material. If a leak occurs at this point, causing air intrusion, the gas-sensitive material rapidly changes color, achieving in-situ, visual, and precise early warning of leaks, effectively reducing blade scrap rates.

[0051] Furthermore, the core material of the microcapsule 4 is a nitrogen dioxide sensitive system or an oxygen sensitive system.

[0052] In this embodiment, the core material of the microcapsule 4 is a nitrogen dioxide-sensitive system, the gas-sensitive color-changing material is 5,10,15,20-tetraphenylporphyrin (TPP), and the temperature-responsive material is modified polyurea with a response temperature of 45~55℃; the substrate of the intermediate layer 12 is ethylene-vinyl acetate copolymer (EVA). When the vacuum bag film leaks, the observed color change is from purple to green.

[0053] In this embodiment, the vacuum bag film is purple at 25°C. After the leaf infusion is complete, the product temperature gradually rises to 45-55°C, causing the wall material of microcapsule 4 to rupture and releasing the gas-sensitive color-changing material from the core. When air enters through a micropore, the gas-sensitive color-changing material rapidly changes color, thus accurately locating the leak point. This serves as a leak warning, allowing personnel to observe the color change area and initiate emergency leak handling procedures.

[0054] Nitrogen dioxide is present in low concentrations in the air, so it needs to be introduced into the air during leaf irrigation.

[0055] Specifically, the content of microcapsules 4 in the intermediate layer 12 is 15~35wt%.

[0056] Preferably, the content of microcapsules 4 in the intermediate layer 12 is 20~30wt%.

[0057] In this embodiment, the content of microcapsules 4 in the intermediate layer 12 is 20 wt%.

[0058] Specifically, both the upper protective layer 11 and the lower protective layer 13 are made of nylon 6 (PA6).

[0059] Furthermore, the vacuum bag film is a multilayer composite film, and the number of layers in the vacuum bag film is ≥3.

[0060] like Figure 1 As shown, in this embodiment, the vacuum bag film has 3 layers.

[0061] Furthermore, there is no specific limitation on the number of layers of the upper protective layer 11. The number of layers of the upper protective layer 11 can be one, two, or three, etc., and is not limited to this.

[0062] like Figure 1 As shown, in this embodiment, the upper protective layer 11 is a single layer.

[0063] Furthermore, the number of layers of the lower protective layer 13 is not specifically limited. The number of layers of the lower protective layer 13 can be one, two, or three, etc., and is not limited to this.

[0064] like Figure 1 As shown, in this embodiment, the lower protective layer 13 is a single layer.

[0065] Furthermore, the dry film thickness of the intermediate layer 12 is 15~60μm.

[0066] Preferably, in this embodiment, the dry film thickness of the intermediate layer 12 is 20~25μm.

[0067] Furthermore, the average particle size of the microcapsule 4 is 9~11 μm.

[0068] In this embodiment, the average particle size of microcapsules 4 is 10 μm.

[0069] This invention also provides a method for preparing a vacuum bag film with a self-early warning function, such as... Figure 2As shown, the preparation method is used to prepare a vacuum bag membrane with a leakage self-early warning function as described in any one of the claims. The preparation method includes the following steps:

[0070] The preparation method includes the following steps:

[0071] S1. Preparation of microcapsules 4: Microcapsule 4 powder was obtained by in-situ polymerization or interfacial polymerization of the oil phase and aqueous phase.

[0072] S2, Preparation of intermediate layer 12: Microcapsule 4 powder is added to the substrate of intermediate layer 12, stirred and dispersed evenly to obtain an aqueous coating solution for coating, which is then coated on the lower protective layer 13 or the upper protective layer 11 at <40℃ and dried.

[0073] S3. Multilayer composite: The upper protective layer 11, the middle layer 12 and the lower protective layer 13 are composited using a dry composite or solvent-free composite process. After completion, the composite is cured at a temperature of <42℃ to obtain a vacuum bag film with a leakage self-warning function.

[0074] The method for preparing the vacuum bag membrane with self-early warning function described in this invention has steps S1 to S3 that are interconnected. The temperature of the entire preparation process is <42℃ to prevent premature triggering of the microcapsule 4.

[0075] Specifically, the process of obtaining microcapsules from the oil phase and aqueous phase using in-situ polymerization or interfacial polymerization includes the following steps:

[0076] First, the oil phase and aqueous phase were pre-degassed under vacuum conditions. After pre-degassed, a vacuum emulsion was prepared in a vacuum reactor by dripping the oil phase into the aqueous phase while continuously stirring. Then, low-temperature interfacial polymerization was carried out by raising the reactor temperature to 35°C, maintaining a vacuum of 0.08 MPa, stirring at a constant speed of 300 rpm for 2-3 hours. After the reaction, the vacuum was maintained and the temperature was lowered to 25°C. The microcapsule phase 4 was separated by centrifugation at 3000 rpm for 5 minutes and then transferred to a vacuum drying oven and dried at 35°C for 4 hours to obtain microcapsule phase 4 powder.

[0077] More specifically, the vacuum degree during the pre-degassing treatment is 0.09 MPa, the stirring speed during the pre-degassing treatment is 300 rpm, and the pre-degassing treatment time is 30 min.

[0078] More specifically, in step S1, the oil phase comprises the following components by weight percentage: core material 0.5-5%, wall material monomer A 10-25%, and oil phase substrate 70-85%, and the aqueous phase comprises the following components by weight percentage: water 85-95%, emulsifier 1-5%, wall material monomer B 0.5-5%, and modifier 0-2%, and the mass ratio of the oil phase to the aqueous phase is 1:2 to 1:5.

[0079] The modifier can be adipic acid dihydrazide.

[0080] In this embodiment, the oil phase comprises the following components by weight percentage: 2% core material, 20% wall material monomer A, and 78% oil phase substrate; the aqueous phase comprises the following components by weight percentage: 92% water, 3% emulsifier, and 5% wall material monomer B; and the mass ratio of the oil phase to the aqueous phase is 1:3.

[0081] Specifically, in step S1, the core material is 5,10,15,20-tetraphenylporphyrin, the wall material monomer A is isophorone diisocyanate (IPDI), the oil phase substrate is liquid paraffin with a melting point of 46°C, the emulsifier is Tween-80, and the wall material monomer B is ethylenediamine.

[0082] Specifically, in step S2, in this embodiment, the microcapsule 4 powder is added to the ethylene-vinyl acetate copolymer, stirred and dispersed evenly to obtain an aqueous coating liquid, which is then coated on the lower protective layer 13 at 38°C and dried.

[0083] In step S2, the coating amount in the dry weight state is 15 ~ 50 g / m².

[0084] In step S2, in this embodiment, the coating amount in the dry weight state is 30 g / m².

[0085] In step S3, a solvent-free lamination process is used to laminate the upper protective layer 11, the middle layer 12 and the lower protective layer 13 using a composite roller. After completion, the lamination is cured at 38°C for 24 hours to obtain a vacuum bag film with a self-early warning function for air leakage.

[0086] Specifically, in step S3, the solvent-free adhesive is a polyurethane adhesive.

[0087] Example 2

[0088] In this embodiment, unlike Embodiment 1, the core material of the microcapsule 4 is an oxygen-sensitive system, the gas-sensitive color-changing material is reduced methylene blue and glucose, the temperature-responsive material is a cross-linked polyurea / polyurethane shell, and the substrate of the intermediate layer 12 is waterborne polyurethane. When the vacuum bag film leaks, the observed color change is from milky white or translucent to dark blue.

[0089] In this embodiment, the vacuum bag film is milky white or translucent at 25°C. When the leaf filling is completed, the product temperature gradually rises to 45-55°C, causing the wall material of microcapsule 4 to rupture and releasing the gas-sensitive color-changing material in the core. When air enters through a micropore, the gas-sensitive color-changing material turns dark blue upon contact with oxygen, serving as a leak warning. Personnel then proceed to the area where the color has changed to perform emergency leak handling.

[0090] In this embodiment, the content of microcapsules 4 in the intermediate layer 12 is 25 wt%.

[0091] More specifically, the process of obtaining microcapsules 4 by in-situ polymerization or interfacial polymerization of the oil and aqueous phases includes the following steps:

[0092] An oil phase was prepared and deoxygenated; an aqueous phase was also prepared and deoxygenated. Under an inert atmosphere or in the absence of oxygen, the oil phase was dispersed in the aqueous phase to prepare an emulsion, which was then subjected to low-temperature interfacial polymerization at 40°C. The interfacial polymerization was carried out under a vacuum of 0.08 MPa and stirred at a constant speed of 300 rpm for 3 hours. After the interfacial polymerization was completed, the microcapsule phase 4 was separated by centrifugation at 3000 rpm for 5 minutes and then transferred to a vacuum drying oven and dried at 35°C for 4 hours to obtain microcapsule phase 4 powder.

[0093] The emulsifier is styrene-maleic anhydride copolymer (SMA), the wall material monomer A is isophorone diisocyanate (IPDI), and the wall material monomer B is diethylenetriamine (DETA).

[0094] More specifically, the preparation of the oil phase and the deoxygenation treatment of the oil phase include the following steps: take 78% liquid paraffin (melting point 46℃) as the oil phase base, purge with high-purity nitrogen for 15 minutes to remove dissolved oxygen, and under continuous nitrogen protection and light-proof conditions, add 2% reduced methylene blue and 20% isophorone diisocyanate (IPDI), stir evenly, at this time the oil phase is colorless or pale yellow and transparent.

[0095] More specifically, the preparation and deoxygenation of the aqueous phase includes the following steps: Take 92% deionized water, add 3% styrene-maleic anhydride copolymer (SMA) and 5% diethylenetriamine (DETA). The aqueous phase is then subjected to ultrasonic degassing or nitrogen purging.

[0096] More specifically, in this embodiment, under a nitrogen atmosphere, the oil phase is dispersed in the aqueous phase and emulsified at a high speed of 3000 rpm for 5 minutes to prepare an emulsion; then the stirring speed is reduced and the interfacial polymerization reaction is carried out at 40°C for 3 hours.

[0097] In step S2, the microcapsule 4 powder is dispersed in waterborne polyurethane (WPU).

[0098] Example 3

[0099] In this embodiment, unlike in embodiment 2, the substrate of the intermediate layer 12 is a VAE emulsion.

[0100] The content of microcapsules 4 in the intermediate layer 12 is 30 wt%.

[0101] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A vacuum bag film with a self-prevention function for air leakage, characterized in that, The vacuum bag film includes at least an upper protective layer (11), a middle layer (12), and a lower protective layer (13). The core-shell structured microcapsules (4) are dispersed in the intermediate layer (12). The core material of the microcapsules (4) is a gas-sensitive color-changing material, and the wall material of the microcapsules (4) is a temperature-responsive material with a response temperature of 45~55℃.

2. The vacuum bag film with leakage self-warning function according to claim 1, characterized in that, The core material of the microcapsule (4) is a nitrogen dioxide sensitive system or an oxygen sensitive system.

3. A vacuum bag film with a self-prevention function for air leakage as described in claim 2, characterized in that, The core material of the microcapsule (4) is a nitrogen dioxide sensitive system, the gas-sensitive color-changing material is 5,10,15,20-tetraphenylporphyrin, the temperature-responsive material is modified polyurea, and the substrate of the intermediate layer (12) is ethylene-vinyl acetate copolymer.

4. A vacuum bag film with a self-prevention function for air leakage as described in claim 2, characterized in that, The core material of the microcapsule (4) is an oxygen-sensitive system, the gas-sensitive color-changing material is reduced methylene blue and glucose, the temperature-responsive material is a cross-linked polyurea / polyurethane shell, and the substrate of the intermediate layer (12) is waterborne polyurethane or VAE emulsion.

5. A vacuum bag film with a self-prevention function for air leakage as described in claim 1, characterized in that, The content of microcapsules (4) in the intermediate layer (12) is 15~35wt%.

6. A vacuum bag film with a self-prevention function for air leakage as described in claim 1, characterized in that, The average particle size of the microcapsules (4) is 9~11 μm.

7. A vacuum bag film with a self-prevention function for air leakage as described in claim 1, characterized in that, The dry film thickness of the intermediate layer (12) is 15~60um.

8. A vacuum bag film with a self-prevention function for air leakage as described in claim 1, characterized in that, The upper protective layer (11) and the lower protective layer (13) are both made of nylon 6.

9. A method for preparing a vacuum bag film with a self-prevention function for air leakage, characterized in that, The preparation method is used to prepare a vacuum bag membrane with a leakage self-early warning function as described in any one of claims 1 to 8, and the preparation method includes the following steps: S1. Preparation of microcapsules (4): Microcapsule (4) powder was obtained by in-situ polymerization or interfacial polymerization of oil phase and aqueous phase; S2, Preparation of intermediate layer (12): Microcapsule (4) powder is added to the substrate of intermediate layer (12), stirred and dispersed evenly to obtain an aqueous coating liquid. The coating is applied to the lower protective layer (13) or upper protective layer (11) at <40℃ and then dried. S3, Multilayer composite: The upper protective layer (11), the middle layer (12) and the lower protective layer (13) are composited and then cured at a temperature of <42℃ to obtain a vacuum bag film with a self-warning function for air leakage.

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