A method of packaging an ionic polymer hydrophone

Abstract

The application provides a packaging method of an ion polymer hydrophone, and belongs to the technical field of underwater acoustic sensing. A sensitive film used in the ion polymer hydrophone is provided first. The size of the sensitive film is used to design the size of a corresponding upper cover plate, a lower cover plate, an insert and a pouring space. The upper cover plate and the lower cover plate are buckled and fixedly connected through screws. The insert is fixed in a sliding table structure groove of the upper cover plate and the lower cover plate. A prepared polyurethane solution is injected, and an ion polymer hydrophone pressure-resistant shell is obtained after solidification. The inner wall of the ion polymer hydrophone pressure-resistant shell is arranged with a positive copper sheet electrode and a negative copper sheet electrode. A dry sensitive film is inserted between the positive copper sheet electrode and the negative copper sheet electrode. Water is injected into the ion polymer hydrophone pressure-resistant shell, so that the dry sensitive film is fully swelled into a swelled sensitive film. The cavity bubbles are discharged through a vacuum negative pressure method. Finally, the upper cover plate and the lower cover plate are sealed and solidified by using the polyurethane solution to form a polyurethane sealing layer.

Description

Technical Field

[0001] This invention relates to the field of underwater acoustic sensing technology, and more particularly to a packaging method for an ion polymer hydrophone. Background Technology

[0002] Underwater acoustic detection technology plays a crucial role in ocean exploration. In recent years, with the gradual expansion of national defense and the marine economy into the deep sea, new demands have been placed on underwater acoustic detection technology, making the development of high-sensitivity, low-frequency underwater acoustic detection technology in the deep sea extremely important. Ion polymer materials consist of a polymer network and a solvent, containing one or more ions that can move freely over long distances in the solvent. Typical examples of ion polymers include hydrogels, ionogels, and ion exchange resins, with water or ionic liquids as the solvent. Through special structural design, ion polymers can achieve an equivalent piezoelectric coefficient of 5–10 nC / N, which is 1–2 times higher than that of piezoelectric single crystals. They are formed through polymer solution coating or casting, without requiring high electric field polarization of the membrane material, resulting in a simple manufacturing process and low costs for raw materials and molding equipment. Therefore, they have enormous application potential in low-frequency, high-sensitivity hydrophones.

[0003] However, ionomers are special polymer materials that exhibit excellent underwater acoustic sensing performance only when they contain moisture, and they can also withstand high hydrostatic pressure. Traditional hydrophones typically use vulcanized rubber encapsulation, which involves a high-temperature vulcanization process. Applying traditional encapsulation methods to ionomer hydrophones makes it difficult to guarantee the internal moisture content, affecting their sensing performance and pressure resistance. Summary of the Invention

[0004] The purpose of this invention is to provide a packaging method for ion polymer hydrophones, which can solve the problem of water retention packaging of hydrophones, while ensuring their high sensitivity and resistance to high hydrostatic pressure.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A method for encapsulating an ionomer hydrophone, characterized by comprising the following steps: S1. Mold Design: First, a sensitive membrane for use in an ion polymer hydrophone is provided. Based on the size of the sensitive membrane, the corresponding dimensions of the upper cover plate, lower cover plate, insert and casting space are designed. The upper cover plate and lower cover plate have the same shape and structure. Both the upper cover plate and lower cover plate are provided with a sliding table structure. Grooves are provided on the upper cover plate, lower cover plate and sliding table structure.

[0006] S2. Casting and molding: The upper and lower cover plates are snapped together and fixed with screws. The insert is fixed in the groove of the slide structure of the upper and lower cover plates. The prepared polyurethane solution is injected and cured to obtain the pressure-resistant housing of the ion polymer hydrophone.

[0007] S3. Component assembly: Positive and negative copper electrodes are arranged on the inner wall of the pressure-resistant housing of the ion polymer hydrophone. Leads are provided on both the positive and negative copper electrodes. A dry sensitive membrane is inserted between the positive and negative copper electrodes.

[0008] S4. Water Injection Encapsulation: Water is injected into the pressure-resistant housing of the ion polymer hydrophone, so that the dry sensitive membrane is fully swollen into a swollen sensitive membrane. The swollen sensitive membrane is in full contact with the positive copper electrode and the negative copper electrode. Air bubbles in the cavity are removed by vacuum negative pressure method. Finally, polyurethane solution is used to seal and cure the upper and lower cover plates to form a polyurethane seal layer.

[0009] Furthermore, in step S4, the dry-state sensitive membrane is allowed to fully swell for no less than 4 hours.

[0010] Furthermore, in step S2, the pressure-resistant housing of the ion polymer hydrophone has a flat structure with a feature size of 5mm-60mm, the thickness L1 of the insert is 0.3mm-2mm, and the thickness between the insert and the inner walls on both sides of the upper and lower cover plates is not less than 2mm.

[0011] Furthermore, in step S3, the materials of the positive copper electrode and the negative copper electrode are metal sheets, gold-plated materials, or carbon-based conductive films, and the thickness of the positive copper electrode and the negative copper electrode does not exceed 0.1 mm.

[0012] Furthermore, in step S3, the thickness of the dry-state sensitive membrane is L2, where L2 ≤ L1 - 0.2 mm.

[0013] Furthermore, in step S2, the material of the insert includes Teflon, acrylic sheet, and metal sheet.

[0014] Furthermore, in steps S2 and S4, the polyurethane solution is cured by room temperature curing and heat curing.

[0015] Furthermore, in step S1, the manufacturing methods of the upper cover plate, the lower cover plate, and the insert include additive manufacturing and machining.

[0016] Further, in step S1, a release agent is sprayed onto the upper cover plate, the lower cover plate, and the insert.

[0017] Furthermore, in step S2, the upper cover plate and the lower cover plate are connected by 3-5 screws.

[0018] Advantages of this invention: 1. The encapsulation method of the present invention utilizes the swelling property of the film to form an interference fit with the reserved space for fixation, thereby overcoming the problem of excessive contact causing polymer extrusion deformation, which leads to poor sensor sensitivity and short measurement range. 2. The encapsulation method of the present invention avoids the damage to the aqueous environment in which the sensitive membrane works by heating in the traditional vulcanization process by first casting a pressure-resistant shell mold with reserved space and then placing the sensitive membrane. 3. The encapsulation method of the present invention ensures that the signal from the water is minimized during transmission through the water-polyurethane-water-sensitive membrane by controlling the water injection time and removing air bubbles in the water. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the assembly of the upper cover plate, lower cover plate, and insert piece in this invention; Figure 2 This is a schematic diagram of the structure of the positive copper electrode and the negative copper electrode inserted into the dry-state sensitive membrane in this invention; Figure 3 This is a schematic diagram showing the combination of the swollen state sensitive membrane with the positive and negative copper electrodes in this invention. Figure 4 This is a schematic diagram of the sealed ion polymer hydrophone in this invention; In the diagram: 1. Top cover plate, 2. Bottom cover plate, 3. Insert plate, 4. Ion polymer hydrophone pressure-resistant housing, 5. Positive copper electrode, 6. Negative copper electrode, 7. Dry state sensitive membrane, 8. Swelling state sensitive membrane, 9. Polyurethane sealing layer. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention.

[0021] A method for encapsulating an ionomer hydrophone includes the following steps: S1. Mold design: such as Figure 1 As shown, a sensitive membrane for use in an ionomer hydrophone is first provided. The dimensions of the upper cover plate 1, lower cover plate 2, insert 3, and casting space are designed according to the size of the sensitive membrane. The upper cover plate 1 and lower cover plate 2 have the same shape and structure. Both the upper cover plate 1 and lower cover plate 2 are provided with a sliding table structure, and grooves are provided on the upper cover plate 1, lower cover plate 2, and sliding table structure. By setting the sliding table structure, a narrow slit space is naturally formed between the upper cover plate 1 and lower cover plate 2, which facilitates the insertion piece 3 to pass through.

[0022] S2. Casting and molding: The upper cover plate 1 and the lower cover plate 2 are fastened together and fixed with screws. The insert 3 is fixed in the groove of the sliding structure of the upper cover plate 1 and the lower cover plate 2. The insert 3 is a gap reserved for placing the dry sensitive membrane 7 in the pressure-resistant housing 4 of the encapsulated ion polymer hydrophone. The prepared polyurethane solution is injected and cured to obtain the pressure-resistant housing 4 of the ion polymer hydrophone.

[0023] S3. Component assembly: such as Figure 2 As shown, a positive copper electrode 5 and a negative copper electrode 6 are arranged on the inner wall of the pressure-resistant housing 4 of the ion polymer hydrophone. Leads are provided on both the positive copper electrode 5 and the negative copper electrode 6. A dry sensitive membrane 7 is inserted between the positive copper electrode 5 and the negative copper electrode 6.

[0024] S4. Water-filled encapsulation: such as... Figure 3 As shown, water is injected into the pressure-resistant housing 4 of the ionomer hydrophone. In an aqueous environment, the sensitive membrane absorbs water and swells, causing the dry sensitive membrane 7 to fully swell into a swollen sensitive membrane 8. This enhances the sensing performance of the sensitive membrane. The swollen sensitive membrane 8 makes full contact with the positive copper electrode 5 and the negative copper electrode 6. Air bubbles in the cavity are removed by vacuuming to avoid unnecessary losses during sound wave propagation and ensure reliable sound transmission. Figure 4 As shown, the upper cover plate 1 and the lower cover plate 2 are finally sealed and cured with polyurethane solution to form a polyurethane seal layer 9.

[0025] In a preferred embodiment of the present invention, in step S2, the sensitive membrane is placed in the air for 8 hours to dehydrate and form a dry sensitive membrane 7.

[0026] In a preferred embodiment of the present invention, in order to provide a sufficiently uniform aqueous environment, the dry-state sensitive membrane 7 should not touch the bottom of the ion polymer hydrophone pressure-resistant housing 4.

[0027] In a preferred embodiment of the present invention, in step S4, the time for the dry-state sensitive membrane 7 to fully swell is not less than 4 hours.

[0028] In a preferred embodiment of the present invention, in step S2, the pressure-resistant housing 4 of the ion polymer hydrophone has a flat structure with a characteristic size of 5mm-60mm, the thickness L1 of the insert 3 is 0.3mm-2mm, and the thickness between the insert 3 and the inner walls on both sides of the upper cover plate 1 and the lower cover plate 2 is not less than 2mm.

[0029] In a preferred embodiment of the present invention, in step S3, the positive copper electrode 5 and the negative copper electrode 6 are made of metal sheets with good conductivity and corrosion resistance, gold-plated materials or carbon-based conductive films, and the thickness of the positive copper electrode 5 and the negative copper electrode 6 does not exceed 0.1 mm. They are attached to the inner wall of the pressure-resistant housing 4 of the ion polymer hydrophone.

[0030] In a preferred embodiment of the present invention, in step S3, the thickness of the dry state sensitive membrane 7 is L2, where L2 ≤ L1 - 0.2 mm.

[0031] In a preferred embodiment of the present invention, in step S2, the material of the insert 3 includes Teflon, acrylic sheet and metal sheet.

[0032] In a preferred embodiment of the present invention, in steps S2 and S4, the polyurethane solution is cured by room temperature curing and heat curing. The curing conditions are: 24 hours at room temperature (25°C); 60°C for 60-90 minutes; and 80°C for 45-65 minutes.

[0033] As a preferred embodiment of the present invention, the polyurethane solution is prepared by mixing AB glue in a certain weight ratio, for example, by mixing and stirring in a weight ratio of 5:1. The polyurethane solution will have obvious bubbles when it is first prepared, and needs to be left to stand until the obvious bubbles are no longer visible to the naked eye.

[0034] As a preferred embodiment of the present invention, since the injection mold is small in size, in order to ensure that the polyurethane solution is evenly distributed in the mold, a dispensing bottle and a filling needle are used to evenly inject the polyurethane solution into the mold.

[0035] In a preferred embodiment of the present invention, in step S1, the upper cover plate 1, the lower cover plate 2 and the insert 3 are manufactured by additive manufacturing and machining.

[0036] In a preferred embodiment of the present invention, in step S1, a release agent is sprayed onto the upper cover plate 1, the lower cover plate 2, and the insert 3 to prevent difficulties in demolding. The release agent is a 717 epoxy resin high-temperature resistant release agent. Before use, it should be shaken thoroughly and sprayed evenly from a distance of about 20-30cm from the mold, after which it can be used.

[0037] In a preferred embodiment of the present invention, in step S2, the upper cover plate 1 and the lower cover plate 2 are connected by 3-5 screws.

[0038] Example 1: The upper cover plate 1 and the lower cover plate 2 are fixed with four screws of 4mm diameter. The dimensions of the upper cover plate 1 and the lower cover plate 2 (without the slide structure) are 5mm wide, 60mm long, and 40mm deep. The slide structure is a rectangular structure with dimensions of 15mm on both sides. The dimensions of the casting space are 4mm wide, 50mm long, and 35mm deep. A groove with a depth of 0.6mm is pre-reserved on the slide structure and the upper cover plate 1 and the lower cover plate 2. Through the mutual cooperation of the cover plates, a narrow slit space of 55mm long and 1.2mm thick, completely penetrating the mold, is naturally formed between the two cover plates. A Teflon sheet insert 3, 60mm long and 1.2mm thick, completely penetrating the mold, is inserted into this space for subsequent sensitive... Space is provided for the placement of the sensing membrane. The prepared polyurethane solution is poured into the mold and cured at room temperature for 24 hours. The pressure-resistant housing 4 of the ion polymer hydrophone is obtained using a release agent. Positive copper electrode 5 and negative copper electrode 6 are attached to both sides of the pre-reserved gap in the mold as electrodes. The dry sensing membrane 7 is placed in the mold and water is injected into the mold for 8 hours to make the dry sensing membrane 7 completely immersed in an aqueous environment. The dry sensing membrane 7 expands into a swollen sensing membrane 8 under the swelling effect and adheres to the electrode sheets. Air bubbles in the water are removed by pressurization to ensure that the signal from the water is transmitted through the water-polyurethane-water-sensing membrane with minimal loss. Finally, the upper cover plate 1 and the lower cover plate 2 are sealed and cured with polyurethane solution to form a polyurethane seal layer 9.

[0039] Example 2: The upper cover plate 1 and the lower cover plate 2 are fixed with four screws of 4mm diameter. The dimensions of the upper cover plate 1 and the lower cover plate 2 (without the slide structure) are 5mm wide, 60mm long, and 40mm deep. The slide structure is a rectangular structure with a length and width of 15mm. The casting space is 4mm wide, 50mm long, and 35mm deep. A groove with a depth of 0.5mm is reserved on the slide structure and the upper cover plate 1 and the lower cover plate 2. Through the mutual cooperation of the cover plates, a narrow space of 55mm long and 1mm thick, which completely penetrates the mold, is naturally formed between the two cover plates. A Teflon sheet insert 3 with a length of 60mm and a thickness of 1mm, which completely penetrates the mold, is inserted into this space to provide space for the subsequent placement of the sensitive membrane. By pouring the prepared polyurethane solution into the mold and heating it at 60°C for 60 minutes, the pressure-resistant housing 4 of the ion polymer hydrophone is obtained using a release agent. A conductive solution is sprayed on both sides of the dry-state sensitive membrane 7 to enhance conductivity. The sprayed dry-state sensitive membrane 7 is then placed in the mold, and water is injected into the mold for 12 hours to ensure that the dry-state sensitive membrane 7 is completely in an aqueous environment. After the dry-state sensitive membrane 7 expands under the swelling effect, it becomes a swollen sensitive membrane 8 that adheres to the electrode sheet. Air bubbles in the water are removed by pressurization to ensure that the signal from the water is transmitted through the water-polyurethane-water-sensitive membrane with minimal loss. Finally, the upper cover plate 1 and the lower cover plate 2 are sealed and cured with polyurethane solution to form a polyurethane seal layer 9.

[0040] In summary, this invention avoids the impact of high temperatures on the performance of the sensitive membrane by directly inserting the sensitive membrane into the pressure-resistant housing of the ionomer hydrophone; it overcomes the problem of reduced sensor sensitivity and shortened measurement range caused by excessive contact leading to polymer extrusion deformation by utilizing the swelling property of the membrane to form an interference fit with the reserved space for fixation; and it ensures that the membrane is completely immersed in an aqueous environment by controlling the water injection time and removing air bubbles in the water by pressurization, thus minimizing signal loss during the transmission process from the water through the polyurethane-water-sensitive membrane.

[0041] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art can still adjust the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Therefore, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention also intends to include these modifications and variations.

Claims

1. A method for encapsulating an ionomer hydrophone, characterized in that, Includes the following steps: S1. Mold design: First, a sensitive membrane for use in an ion polymer hydrophone is provided. The dimensions of the upper cover plate (1), lower cover plate (2), insert (3) and casting space are designed according to the size of the sensitive membrane. The upper cover plate (1) and lower cover plate (2) have the same shape and structure. Both the upper cover plate (1) and lower cover plate (2) are provided with a sliding table structure. The upper cover plate (1), lower cover plate (2) and sliding table structure are provided with grooves. S2. Casting: The upper cover plate (1) and the lower cover plate (2) are fastened together and fixed with screws. The insert (3) is fixed in the groove of the sliding structure of the upper cover plate (1) and the lower cover plate (2). The prepared polyurethane solution is injected and cured to obtain the pressure-resistant housing (4) of the ion polymer hydrophone. S3. Component assembly: Positive copper electrode (5) and negative copper electrode (6) are arranged on the inner wall of the pressure-resistant housing (4) of the ion polymer hydrophone. Lead wires are provided on both the positive copper electrode (5) and the negative copper electrode (6). A dry sensitive membrane (7) is inserted between the positive copper electrode (5) and the negative copper electrode (6). S4. Water injection and encapsulation: Water is injected into the pressure-resistant housing (4) of the ion polymer hydrophone so that the dry state sensitive membrane (7) is fully swollen into the swollen state sensitive membrane (8). The swollen state sensitive membrane (8) is in full contact with the positive copper electrode (5) and the negative copper electrode (6). The air bubbles in the cavity are discharged by vacuum negative pressure method. Finally, the upper cover plate (1) and the lower cover plate (2) are sealed and cured with polyurethane solution to form a polyurethane seal layer (9).

2. The encapsulation method for an ionomer hydrophone according to claim 1, characterized in that: In step S4, the dry-state sensitive membrane (7) is allowed to fully swell for no less than 4 hours.

3. The encapsulation method for an ionomer hydrophone according to claim 2, characterized in that: In step S2, the pressure-resistant housing (4) of the ion polymer hydrophone is a flat structure with a feature size of 5mm-60mm. The thickness L1 of the insert (3) is 0.3mm-2mm. The thickness between the insert (3) and the inner walls on both sides of the upper cover plate (1) and the lower cover plate (2) is not less than 2mm.

4. The encapsulation method for an ionomer hydrophone according to claim 3, characterized in that: In step S3, the positive copper electrode (5) and the negative copper electrode (6) are made of metal sheet, gold-plated material or carbon-based conductive film, and the thickness of the positive copper electrode (5) and the negative copper electrode (6) does not exceed 0.1 mm.

5. The encapsulation method for an ionomer hydrophone according to claim 4, characterized in that: In step S3, the thickness of the dry state sensitive membrane (7) is L2, where L2 ≤ L1 - 0.2 mm.

6. The encapsulation method for an ionomer hydrophone according to claim 5, characterized in that: In step S2, the materials of the insert (3) include Teflon, acrylic sheet and metal sheet.

7. The encapsulation method for an ionomer hydrophone according to claim 6, characterized in that: In steps S2 and S4, the polyurethane solution is cured by room temperature curing and heat curing.

8. The encapsulation method for an ionomer hydrophone according to claim 7, characterized in that: In step S1, the manufacturing methods of the upper cover plate (1), the lower cover plate (2) and the insert (3) include additive manufacturing and machining.

9. The encapsulation method for an ionomer hydrophone according to claim 8, characterized in that: In step S1, release agent is sprayed onto the upper cover plate (1), the lower cover plate (2) and the insert (3).

10. The encapsulation method for an ionomer hydrophone according to claim 9, characterized in that: In step S2, the upper cover plate (1) and the lower cover plate (2) are connected by 3-5 screws.

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