Moisture-proofing method for a wave-transparent material

Abstract

This invention provides a method for moisture-proofing a microwave-transparent material, comprising the following steps: S1. applying a hydrophobic coating to the outer surface of the microwave-transparent material; S2. hot-pressing a hot melt adhesive film onto the outer surface of the hydrophobic coating; S3. hot-pressing a high-barrier film onto the outer surface of the hot melt adhesive film; S4. curing the microwave-transparent material treated in step S3 to complete the moisture-proofing treatment. This moisture-proofing method uses a hot melt adhesive film with adhesive properties to bond a high-barrier film to the surface of the microwave-transparent material via hot pressing. The high-barrier film effectively blocks moisture, significantly reducing the moisture absorption rate of the microwave-transparent material. The method is simple to operate, has strong adhesion, and the hot melt adhesive film and high-barrier film have good dielectric properties, without affecting the microwave-transparent performance of the material.

Description

Technical Field

[0001] This invention belongs to the field of wave-transparent material technology, and specifically relates to a moisture-proof treatment method for wave-transparent materials. Background Technology

[0002] As a crucial component for the normal operation of radar antenna systems, wave-transparent materials must possess stable wave-transmitting performance. Currently, the wave-transmitting materials successfully applied both domestically and internationally mainly include quartz fiber / resin-based composite materials, quartz ceramic materials, and quartz fiber-reinforced ceramic matrix composite materials. However, all of these materials suffer from the drawback of absorbing moisture. Because water has a very high dielectric constant and dielectric loss (approximately 76 dielectric constant and 12 dielectric loss tangent at 25℃), moisture absorption in wave-transmitting materials leads to an increase in their dielectric constant and loss angle, resulting in reduced wave-transmitting performance and consequently, radar aiming errors.

[0003] Currently, there are generally two methods to solve the moisture absorption problem of microwave-transparent materials: one is to prepare a moisture-proof coating on its surface; the other is to attach a high-barrier film to its surface. For general microwave-transparent materials, preparing a moisture-proof coating can meet their moisture-proof requirements, with a 7-day moisture absorption rate of less than 0.03%. However, for some microwave-transparent materials with extremely high requirements for both microwave transmission performance and moisture resistance, the 7-day moisture absorption rate must be less than 0.01%. Therefore, preparing a coating is no longer sufficient to meet the moisture-proof requirements, and it is necessary to attach a high-barrier film with good water barrier properties for moisture protection. However, since high-barrier films do not have adhesive properties, they cannot be directly attached to the surface of microwave-transparent materials. Adheding the high-barrier film to the surface of the microwave-transparent material using adhesives not only results in poor adhesion and easy detachment of the high-barrier film, but also significantly affects the overall microwave transmission performance of the material. Summary of the Invention

[0004] The technical problem solved by this invention is to provide a moisture-proof treatment method for microwave-transparent materials. A high-barrier film is bonded to the surface of the microwave-transparent material by hot pressing with a hot melt adhesive film that has an adhesive effect. The high-barrier film can effectively block water vapor, greatly reduce the moisture absorption rate of the microwave-transparent material, and the operation is simple, with strong adhesion. The hot melt adhesive film and the high-barrier film have good dielectric properties and do not affect the microwave transmission performance of the material.

[0005] To address the above problems, this invention provides a method for moisture-proofing a wave-transparent material, comprising the following steps:

[0006] S1. Apply a hydrophobic coating to the outer surface of the wave-transparent material;

[0007] S2. Hot melt adhesive film is hot-pressed onto the outer surface of the hydrophobic coating;

[0008] S3. A high-barrier film is hot-pressed onto the outer surface of the hot melt adhesive film;

[0009] S4. Cure the microwave-transparent material after step S3 to complete the moisture-proof treatment of the microwave-transparent material.

[0010] Preferably, the hydrophobic coating is made of an organosilicon polymer hydrophobic material or an alkane compound hydrophobic material.

[0011] Preferably, the hot melt adhesive film is made of at least one of polyurethane, polyamide, polyethersulfone, ethylene-vinyl acetate copolymer, and propylene oxide.

[0012] Preferably, the high-barrier film is at least one of PA / PE co-extruded film, ethylene-vinyl alcohol copolymer film, and high-density polyethylene film.

[0013] Preferably, the thickness of the hot melt adhesive film is 0.04-0.3 mm; and the thickness of the high barrier film is 0.04-0.2 mm.

[0014] Preferably, step S4 specifically involves wrapping the microwave-transparent material treated in step S3 entirely in a vacuum bag and curing it for 2-4 hours at a pressure below -0.08 MPa and a temperature of 80-150°C.

[0015] Preferably, the dielectric constant of the hot melt adhesive film and / or the high barrier film is 2.0-3.0, and the dielectric loss tangent is ≤0.005.

[0016] Preferably, the aging failure period of the hot melt adhesive film and / or the high barrier film is greater than 30 years.

[0017] Preferably, in steps S2 and S3, the hot pressing is performed using at least one of an iron, a steam iron, a high-frequency machine, and an infrared heater.

[0018] Preferably, before step S2, the hot melt adhesive film and the high barrier film are designed according to the shape and structure of the wave-transparent material, and the hot melt adhesive film and the high barrier film are cut using a fabric cutting machine according to the cutting and unfolding diagram.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] The moisture-proofing method for the wave-transparent material of this invention employs a barrier film for moisture protection. Compared to a moisture-proof coating, this film has a more uniform texture and stronger barrier properties. The moisture-proofed wave-transparent material exhibits excellent wave transmission performance, mechanical properties, and environmental resistance. A hot-melt adhesive film is used to bond the wave-transparent material and the barrier film, resulting in good adhesion and a more reliable bond between the barrier film and the wave-transparent material substrate. A hydrophobic coating is also applied between the hot-melt adhesive film and the wave-transparent material, further enhancing the moisture-proofing effect. Furthermore, the high-barrier film and the hot-melt adhesive film have good conformability, allowing them to conform to wave-transparent materials of various shapes, thereby improving bonding strength. In addition, this moisture-proofing method is simple in process, convenient to operate, low in cost, highly practical, and has broad application prospects. Detailed Implementation

[0021] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] Using a moisture-proof coating to treat the wave-transparent material cannot meet the requirements of wave-transparent materials with extremely high requirements for wave transmission and moisture-proof performance. Using a high-barrier film to treat the wave-transparent material can meet higher moisture-proof requirements, but the high-barrier film cannot be directly applied to the surface of the wave-transparent material.

[0023] Therefore, embodiments of the present invention provide a method for moisture-proofing a wave-transparent material, comprising the following steps:

[0024] S1. Apply a hydrophobic coating to the outer surface of the wave-transparent material;

[0025] S2. Hot melt adhesive film is hot-pressed onto the outer surface of the hydrophobic coating;

[0026] S3. A barrier film is hot-pressed onto the outer surface of the hot melt adhesive film;

[0027] S4. Cure the microwave-transparent material after step S3 to complete the moisture-proof treatment of the microwave-transparent material.

[0028] The moisture-proof treatment method for the wave-transparent material in this embodiment of the invention uses a barrier film for moisture protection. Compared with a moisture-proof coating, the barrier film has a more uniform texture and stronger barrier properties. The wave-transparent material after moisture-proof treatment has excellent wave transmission performance, mechanical properties, and environmental resistance. A hot melt adhesive film is used to bond the wave-transparent material and the barrier film, resulting in good adhesion and a more reliable bond between the barrier film and the wave-transparent material substrate. A hydrophobic coating is also applied between the hot melt adhesive film and the wave-transparent material, which can further improve the moisture-proof effect of the wave-transparent material.

[0029] In some embodiments, the hydrophobic coating can be made of various existing hydrophobic materials, such as organosilicon polymer hydrophobic materials or alkane compound hydrophobic materials. The organosilicon polymer hydrophobic material can be methylsiloxane, vinyl acetate-acrylate-silane copolymer, etc. The most preferred hydrophobic coating is a vinyl acetate-acrylate-silane copolymer.

[0030] In some embodiments, the hot melt adhesive film refers to a resin hot melt adhesive film. The material of the hot melt adhesive film can be at least one of polyurethane, polyamide, polyethersulfone, ethylene-vinyl acetate copolymer, and propylene oxide. Preferably, the hot melt adhesive film is at least one of polyamide, polyethersulfone, and ethylene-vinyl acetate copolymer. Using the above-mentioned hot melt adhesive film allows for a stronger bond between the wave-transparent material and the high-barrier film. After hot pressing, the hot melt adhesive film and the high-barrier film are approximately fused together, exhibiting strong adhesion. The most preferred hot melt adhesive film is an ethylene-vinyl acetate copolymer film.

[0031] In some embodiments, a high-barrier film refers to a multilayered film formed by simultaneously extruding a material with strong gas barrier properties and a polyolefin with strong heat-sealing and moisture barrier properties. The high-barrier film can be at least one of PA / PE co-extruded film, ethylene-vinyl alcohol copolymer film, and high-density polyethylene film. Preferably, the high-barrier film is a PA / PE co-extruded film, an ethylene-vinyl alcohol copolymer film, or a high-density polyethylene film. When using the above-mentioned hot melt adhesive film, the wave-transparent material can be effectively and firmly bonded to the high-barrier film without affecting the wave-transparent performance of the material. The most preferred high-barrier film is an ethylene-vinyl alcohol copolymer film.

[0032] The thickness of the hydrophobic coating directly affects the wave transmittance of the wave-transmitting material. If the hydrophobic coating is too thick, it will negatively impact the wave transmittance performance of the material. In some embodiments, the thickness of the hydrophobic coating is ≤0.05mm; the preferred thickness is 0.02mm-0.04mm. Using a hydrophobic coating within this thickness range allows it to exhibit superior hydrophobic effects without reducing the wave transmittance of the material due to excessive thickness. The most preferred thickness of the hydrophobic coating is 0.04mm.

[0033] The thickness of the hot melt adhesive film directly affects the wave transmittance of the wave-transparent material. If the hot melt adhesive film is too thick, it will be detrimental to the wave transmittance performance of the material. In some embodiments, the thickness of the hot melt adhesive film is 0.04-0.3 mm; the preferred thickness is 0.06 mm-0.2 mm. Using a hot melt adhesive film within this thickness range allows the wave-transparent material to be effectively and firmly bonded to the high-barrier membrane without affecting the wave transmittance performance of the material. The most preferred thickness of the hot melt adhesive film is 0.16 mm.

[0034] The thickness of the high-barrier membrane directly affects the wave transmittance of the wave-transmitting material. If the high-barrier membrane is too thick, it will negatively impact the wave transmittance performance of the material; if it is too thin, it will reduce its moisture-proof performance. In some embodiments, the thickness of the high-barrier membrane is 0.04-0.2 mm; preferably, it is 0.06 mm-0.15 mm. Using a high-barrier membrane within this thickness range allows the moisture-proof membrane to provide moisture protection while maintaining the wave transmittance performance of the wave-transmitting material. The most preferred thickness of the high-barrier membrane is 0.10 mm.

[0035] In some embodiments, the dielectric constant of the hot melt adhesive film and / or the high-barrier film is 2.0-3.0, and the dielectric loss tangent is ≤0.005. Using the hot melt adhesive film and high-barrier film with the above properties ensures effective and firm adhesion between the wave-transparent material and the high-barrier film, maintains good wave-transmitting performance of the wave-transparent material, and effectively provides moisture protection.

[0036] In some embodiments, the aging failure period of the hot melt adhesive film and / or the high-barrier film is greater than 30 years. Using the hot melt adhesive film and high-barrier film with the above-described properties ensures that the moisture-proof film remains intact and effective during product storage, preventing failure due to aging, which would reduce the moisture-proof effect and affect the wave transmission performance of the product during use.

[0037] In some embodiments, in step S1, a hydrophobic coating is formed on the outer surface of the wave-transparent material by spraying.

[0038] In some embodiments, before step S2, a cutting and unfolding diagram of the hot melt adhesive film and the high barrier film is designed according to the shape and structure of the wave-transparent material, and the hot melt adhesive film and the high barrier film are cut using a fabric cutting machine according to the cutting and unfolding diagram.

[0039] In some embodiments, in steps S2 and S3, the hot pressing is performed using at least one of an iron, a heat press, a high-frequency machine, and an infrared heater. By hot pressing, the hot melt adhesive film and the high-barrier film can be pre-pressed and bonded together. The hot pressing direction is from one side to the other, which helps to expel as much air as possible between the hot melt adhesive film, the high-barrier film, and the wave-transparent material.

[0040] In some embodiments, step S4 specifically involves encasing the microwave-transparent material treated in step S3 entirely in a vacuum bag and curing it for 2-4 hours at a pressure below -0.08 MPa and a temperature of 80-150°C. Under certain temperature and pressure, the vacuum bag method can remove air bubbles between the membranes and between the membrane and the microwave-transparent material, further strengthening the adhesion between the high-barrier membrane, the hot melt adhesive film, and the microwave-transparent material, so that the high-barrier membrane and the hot melt adhesive film are firmly bonded to the surface of the microwave-transparent material. Example 1

[0041] The moisture-proofing treatment method for the wave-transparent material in this embodiment includes the following steps:

[0042] S1. Spray a hydrophobic coating onto the outer surface of the wave-transparent material. The hydrophobic coating is made of vinyl acetate-acrylate-silane copolymer and has a thickness of 0.04 mm.

[0043] S2. Design the cutting and unfolding diagrams of the hot melt adhesive film and the high barrier film according to the shape and structure of the wave-transparent material. Cut the hot melt adhesive film and the high barrier film using a fabric cutting machine according to the cutting and unfolding diagrams. Then, use a heat press machine to hot press the hot melt adhesive film onto the outer surface of the hydrophobic coating of the wave-transparent material. The material of the hot melt adhesive film is ethylene-vinyl acetate copolymer, the thickness of the hot melt adhesive film is 0.16mm, the dielectric constant of the hot melt adhesive film is 2.2, and the dielectric loss tangent is ≤0.005.

[0044] S3. A high-barrier film is hot-pressed onto the outer surface of the hot melt adhesive film using a heat press machine. The high-barrier film is made of ethylene-vinyl alcohol copolymer film and has a thickness of 0.10 mm.

[0045] S4. Wrap the microwave-transparent material treated in step S3 entirely in a vacuum bag and cure it for 3 hours at a pressure below -0.08 MPa and a temperature of 150°C.

[0046] S5. After curing is complete, remove the vacuum bag to obtain the moisture-proof transparent material. Example 2

[0047] The moisture-proofing treatment method for the wave-transparent material in this embodiment includes the following steps:

[0048] S1. Spray a hydrophobic coating onto the outer surface of the wave-transparent material. The hydrophobic coating is made of vinyl acetate-acrylate-silane copolymer and has a thickness of 0.03 mm.

[0049] S2. Design the cutting and unfolding diagrams of the hot melt adhesive film and the high barrier film according to the shape and structure of the wave-transparent material. Cut the hot melt adhesive film and the high barrier film using a fabric cutting machine according to the cutting and unfolding diagrams. Then, use a heat press machine to hot press the hot melt adhesive film onto the outer surface of the hydrophobic coating of the wave-transparent material. The material of the hot melt adhesive film is polyamide, the thickness of the hot melt adhesive film is 0.12mm, the dielectric constant of the hot melt adhesive film is 2.6, and the dielectric loss tangent is ≤0.005.

[0050] S3. A high-barrier film is hot-pressed onto the outer surface of the hot melt adhesive film using a heat press machine. The high-barrier film is made of PA / PE co-extruded film and has a thickness of 0.12mm.

[0051] S4. Wrap the microwave-transparent material treated in step S3 entirely in a vacuum bag and cure it for 4 hours at a pressure below -0.08 MPa and a temperature of 120°C.

[0052] S5. After curing is complete, remove the vacuum bag to obtain the moisture-proof transparent material. Example 3

[0053] The moisture-proofing treatment method for the wave-transparent material in this embodiment includes the following steps:

[0054] S1. Spray a hydrophobic coating onto the outer surface of the wave-transparent material. The hydrophobic coating is made of vinyl acetate-acrylate-silane copolymer and has a thickness of 0.02 mm.

[0055] S2. Design the cutting and unfolding diagrams of the hot melt adhesive film and the high barrier film according to the shape and structure of the wave-transparent material. Cut the hot melt adhesive film and the high barrier film using a fabric cutting machine according to the cutting and unfolding diagrams. Then, use a heat press machine to hot press the hot melt adhesive film onto the outer surface of the hydrophobic coating of the wave-transparent material. The material of the hot melt adhesive film is polyethersulfone, the thickness of the hot melt adhesive film is 0.10mm, the dielectric constant of the hot melt adhesive film is 2.3, and the dielectric loss tangent is ≤0.005.

[0056] S3. A high-barrier film is hot-pressed onto the outer surface of the hot melt adhesive film using a heat press machine. The high-barrier film is made of high-density polyethylene film and has a thickness of 0.08mm.

[0057] S4. Wrap the microwave-transparent material treated in step S3 entirely in a vacuum bag and cure it for 4 hours at a pressure below -0.08 MPa and a temperature of 100°C.

[0058] S5. After curing is complete, remove the vacuum bag to obtain the moisture-proof transparent material. Example 4

[0059] The moisture-proof treatment method for the wave-transparent material in this embodiment is the same as that in Embodiment 1, except that the thickness of the hot melt adhesive film is 0.2 mm. Example 5

[0060] The moisture-proof treatment method for the wave-transparent material in this embodiment is the same as that in Embodiment 1, except that the thickness of the hot melt adhesive film is 0.06 mm. Example 6

[0061] The moisture-proof treatment method for the wave-transparent material in this embodiment is the same as that in Embodiment 1, except that the thickness of the hot melt adhesive film is 0.04 mm. Example 7

[0062] The moisture-proof treatment method for the wave-transparent material in this embodiment is the same as that in Embodiment 1, except that the thickness of the hot melt adhesive film is 0.3 mm. Example 8

[0063] The moisture-proof treatment method for the wave-transparent material in this embodiment is the same as that in Embodiment 1, except that the thickness of the high-barrier film is 0.06 mm. Example 9

[0064] The moisture-proof treatment method for the wave-transparent material in this embodiment is the same as that in Embodiment 1, except that the thickness of the high-barrier film is 0.15 mm. Example 10

[0065] The moisture-proof treatment method for the wave-transparent material in this embodiment is the same as that in Embodiment 1, except that the thickness of the high-barrier film is 0.04 mm. Example 11

[0066] The moisture-proof treatment method for the wave-transparent material in this embodiment is the same as that in Embodiment 1, except that the thickness of the high-barrier film is 0.2 mm.

[0067] The moisture-proof performance of the microwave-transparent materials after moisture-proof treatment in the above embodiments and the adhesion strength between the high-barrier film and the microwave-transparent materials were measured. The results are shown in the table below. As can be seen from the data in Table 1, the difference between Embodiment 1 and Embodiments 4-7 is the thickness of the hot melt adhesive film. When the thickness of the hot melt adhesive film increases to a certain value, the adhesion strength of the microwave-transparent materials does not increase significantly with the increase in the thickness of the hot melt adhesive film, but the microwave transmission performance of the microwave-transparent materials decreases significantly. When the thickness of the hot melt adhesive film decreases to a certain value, the microwave transmission performance of the microwave-transparent materials does not increase significantly with the decrease in the thickness of the hot melt adhesive film, but the adhesion strength decreases significantly. Embodiments 1, 4, and 5 represent preferred hot melt adhesive film thickness ranges. Compared to Examples 8-11, Example 1 differs in the thickness of the high-barrier film. When the thickness of the high-barrier film increases to a certain value, the improvement in the moisture-proof performance of the wave-transparent material is not significant, but the wave-transmitting performance decreases significantly. When the thickness of the high-barrier film decreases to a certain value, the improvement in the wave-transmitting performance of the wave-transparent material is not significant, but the moisture-proof performance decreases significantly. Examples 1, 8, and 9 represent preferred high-barrier film thickness ranges. Example 1 is the most preferred embodiment, in which the wave-transparent material simultaneously possesses better moisture-proof performance, wave-transmitting performance, and adhesive strength.

[0068] Table 1

[0069]

[0070] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A moisture-proofing method for a wave-transparent material, characterized by, Includes the following steps: S1. A hydrophobic coating is applied to the outer surface of the wave-transparent material. The hydrophobic coating is made of vinyl acetate-acrylate-silane copolymer and has a thickness of 0.04 mm. S2. A hot melt adhesive film is hot-pressed onto the outer surface of the hydrophobic coating. The hot melt adhesive film is made of ethylene-vinyl acetate copolymer; the thickness of the hot melt adhesive film is 0.16 mm; the dielectric constant of the hot melt adhesive film is 2.2, and the dielectric loss tangent is ≤0.

005. S3. A high-barrier film is hot-pressed onto the outer surface of the hot melt adhesive film. The high-barrier film is an ethylene-vinyl alcohol copolymer film. The thickness of the high-barrier film is 0.10 mm. The aging failure period of the hot melt adhesive film and the high-barrier film is greater than 30 years. S4. Curing the microwave-transparent material after step S3 to complete the moisture-proof treatment of the microwave-transparent material; Specifically, step S4 involves wrapping the microwave-transparent material after step S3 entirely in a vacuum bag and curing it for 3 hours at a pressure below -0.08 MPa and a temperature of 150°C. In steps S2 and S3, the hot pressing is performed using at least one of an iron, a steam iron, a high-frequency machine, and an infrared heater. Before step S2, the cutting and unfolding diagrams of the hot melt adhesive film and the high barrier film are designed according to the shape and structure of the wave-transparent material, and the hot melt adhesive film and the high barrier film are cut using a fabric cutting machine according to the cutting and unfolding diagrams.