Body of electroacoustic transducer diaphragm, and electroacoustic transducer diaphragm

Abstract

A body of a diaphragm for an electroacoustic transducer, comprising a base layer containing pulp and a resin layer containing an imide-based resin, the base layer and the resin layer being bonded together with an adhesive.

Description

[Technical Field]

[0001] The present disclosure relates to a body of a diaphragm for an electroacoustic transducer and a diaphragm for an electroacoustic transducer. [Background technology]

[0002] Electric vehicles, which are driven by electric motors, produce quieter noise while running than vehicles driven by internal combustion engines. This makes it difficult for pedestrians to recognize approaching vehicles, posing a risk of causing a car accident. Therefore, there is a growing trend to equip electric vehicles with acoustic vehicle alerting systems (AVAS), which emit artificially generated warning sounds outside the vehicle to alert pedestrians of approaching vehicles. For example, Patent Document 1 describes an electric vehicle equipped with an acceleration sensor that detects and outputs a driving state, a warning sound generator that generates a sound based on the detected driving state, and a controller that controls the operation of the warning sound generator.

[0003] Patent document 1: Japanese Patent Application Laid-Open No. 11-27810 Summary of the Invention [Problem to be solved by the invention]

[0004] The vehicle approaching warning device is equipped with a speaker that emits a warning sound. The speaker of the vehicle approaching warning device is installed on the outside of the vehicle body, such as behind the bumper. Therefore, there is a possibility that the speaker may come into contact with chemical products used for cleaning and maintenance of the vehicle body. Therefore, the speaker of the vehicle approaching warning device must have excellent resistance to chemical products. Furthermore, there is a demand for the ability to reproduce a wider variety of sounds, such as artificially generated warning sounds, as well as simulated engine and horn sounds. In view of the above circumstances, an object of one embodiment of the present disclosure is to provide a body of an electroacoustic transducer diaphragm that has excellent chemical resistance and acoustic characteristics, and an electroacoustic transducer diaphragm that includes this body. [Means for solving the problem]

[0005] Specific means for solving the above problems include the following aspects. <1> A body of a diaphragm for an electroacoustic transducer, comprising a base layer containing pulp and a resin layer containing an imide-based resin, the base layer and the resin layer being bonded together with an adhesive. <2> The value of X / Y calculated from the thickness X of the base material layer and the thickness Y of the resin layer is 1 or more. <1> The fuselage described in <3> <1> or <2> A diaphragm for an electroacoustic transducer, comprising the body according to claim 1. <4> An edge is disposed around the fuselage, and a resin layer of the fuselage and the edge are integrally molded. <3> The diaphragm for an electroacoustic transducer according to claim 1. <5> an edge disposed around the fuselage, the fuselage and the edge being separate members; <3> The diaphragm for an electroacoustic transducer according to claim 1. <6> a cap disposed at the center of the body, wherein the resin layer of the body and the cap are integrally molded; <3> The diaphragm for an electroacoustic transducer according to claim 1. <7> Further comprising a damping material; <3> ~ <6> 10. The diaphragm for an electroacoustic transducer according to claim 9, wherein the diaphragm is a diaphragm for an electroacoustic transducer. [Effects of the Invention]

[0006] According to one embodiment of the present disclosure, there are provided a body of an electroacoustic transducer diaphragm having excellent chemical resistance and acoustic characteristics, and an electroacoustic transducer diaphragm including this body. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a cross-sectional view that schematically shows an example of the configuration of an electro-acoustic transducer to which the body of the present disclosure is applied. [Figure 2] FIG. 2 is a partial enlarged view of the body 1 and the edge 2 of the electroacoustic transducer shown in FIG. [Figure 3] FIG. 3 shows a modification of the body 1 and edge 2 shown in FIG. [Figure 4] FIG. 4 shows a modification of the body 1 and edge 2 shown in FIG. [Figure 5] FIG. 5 shows a modification of the body 1 and edge 2 shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments according to the present disclosure will be described. These descriptions and examples are intended to exemplify embodiments according to the present disclosure and are not intended to limit the scope of the invention.

[0009] In the present disclosure, a numerical range indicated using "to" indicates a range that includes the numerical values ​​before and after "to" as the lower and upper limits, respectively.

[0010] In the numerical ranges described in stages in this disclosure, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, in the numerical ranges described in this disclosure, the upper or lower limit value of that numerical range may be replaced with a value shown in the examples.

[0011] In the present disclosure, each component may contain multiple corresponding substances. When referring to the amount of each component in a composition in the present disclosure, if multiple substances corresponding to each component are present in the composition, the total amount of the multiple substances present in the composition is meant unless otherwise specified.

[0012] When describing embodiments of the present disclosure with reference to the drawings, the embodiments of the present disclosure are not limited to the configurations shown in the drawings. The dimensions, shapes, etc. of the components shown in the drawings are conceptual, and the embodiments of the present disclosure are not limited thereto.

[0013] <Body of diaphragm for electroacoustic transducer> The body of the electroacoustic transducer diaphragm of the present disclosure includes a base layer containing pulp, a resin layer containing an imide-based resin, and an adhesive layer disposed between the base layer and the resin layer.

[0014] In this disclosure, an electroacoustic transducer refers to a device that converts an electrical signal into sound (a speaker) or a device that converts sound into an electrical signal (a microphone). An electroacoustic transducer diaphragm refers to a component that vibrates in response to an electrical signal received by the electroacoustic transducer and radiates sound waves into the air. In the present disclosure, the body of the diaphragm for an electroacoustic transducer refers to a plate-like member that vibrates in response to an electric signal among the members that make up the diaphragm. Hereinafter, the electroacoustic transducer diaphragm may be simply referred to as the "diaphragm," and the body of the electroacoustic transducer diaphragm may be simply referred to as the "body."

[0015] The imide-based resin contained in the resin layer of the body of the present disclosure exhibits excellent chemical resistance and long-term heat resistance. However, the acoustic characteristics of a diaphragm using a body containing an imide-based resin leave room for improvement. Factors that affect the acoustic characteristics of a diaphragm include the speed of sound, which is an indicator of the speed at which vibrations travel through the diaphragm; internal loss, which is an indicator of how easily vibrations are contained; and rigidity, which is an indicator of the reproduction of high-amplitude sounds and adaptability to changes in pressure (air pressure, water pressure, etc.). As will be shown in the examples described later, when a resin layer containing an imide-based resin is combined with a base layer containing pulp, the sound velocity and internal loss increase, and the rigidity also increases, compared to the resin layer containing an imide-based resin alone. In other words, the acoustic properties are improved by combining a base layer containing pulp with a resin layer.

[0016] As described above, the fuselage of the present disclosure has an imide-based resin in the resin layer, which achieves excellent chemical resistance and increases the degree of freedom in designing the fuselage to match the performance required of the electro-acoustic transducer, which contributes to realizing a larger fuselage, for example. Furthermore, the fuselage of the present disclosure is expected to have improved acoustic characteristics as well as improvements in the feasibility and cost of the manufacturing process.

[0017] Furthermore, as shown in the examples described below, a laminate combining a resin layer containing an imide-based resin and a base layer containing pulp has a lower density and a higher Young's modulus than a resin layer containing an imide-based resin alone. In other words, the fuselage of the present disclosure can achieve weight reduction and improved strength in addition to improved chemical resistance and acoustic properties.

[0018] (resin layer) The resin layer includes an imide-based resin. In the present disclosure, the imide resin refers to a resin containing an imide bond in the molecular chain, and examples of the imide resin include polyimide (PI), polyetherimide (PEI), and polyamideimide (PAI). Among the imide resins, polyetherimide is preferred from the viewpoint of relatively high flexibility and excellent processability. If necessary, the resin layer may contain additives such as a colorant and an ultraviolet absorber.

[0019] The thickness of the resin layer is not particularly limited, and can be set depending on the use, scale, etc. of the electroacoustic transducer to which the body is applied. From the viewpoint of imparting sufficient chemical resistance to the body, the thickness of the resin layer is preferably 15 μm or more, more preferably 20 μm or more, and even more preferably 30 μm or more. From the viewpoint of maintaining good acoustic properties, the thickness of the resin layer is preferably 300 μm or less, more preferably 200 μm or less, and even more preferably 100 μm or less.

[0020] (base material layer) The substrate layer includes pulp. In this disclosure, pulp refers to a fibrous material obtained from plant materials such as wood or non-plant materials. Non-plant materials include resins such as aramid, polyester, and polyvinyl alcohol, carbon, and glass. Pulp may also be recycled pulp obtained from waste paper. If necessary, the substrate layer may contain additives such as minerals, colorants, binders, etc. Examples of minerals include mica and zirconia. The thickness of the base material layer is not particularly limited, and can be set depending on the use, size, etc. of the electroacoustic transducer to which the body is applied. From the viewpoint of ensuring the rigidity of the fuselage, the thickness of the base material layer is preferably 0.1 mm or more, more preferably 0.15 mm or more, and even more preferably 0.2 mm or more. From the viewpoint of reducing the weight of the fuselage, the thickness of the base material layer is preferably 2.0 mm or less, more preferably 1.0 mm or less, and even more preferably 0.5 mm or less.

[0021] The base material layer and the resin layer are bonded together with an adhesive. The adhesive used to bond the base material layer and the resin layer can be selected from known adhesives such as hot melt adhesives, urethane adhesives, epoxy adhesives, polyethylene adhesives, acrylic adhesives, and silicone adhesives.

[0022] (How to make the body) The fuselage of the present disclosure is produced, for example, by bonding a component that will become the base layer and a component that will become the resin layer with an adhesive. This method allows for efficient production of a fuselage in which the thickness of each layer is precisely controlled. Furthermore, methods in which the resin layer is formed by applying a resin layer material to the surface of a base layer may result in alteration of the base layer and deterioration of quality. By bonding the base layer and resin layer with an adhesive, the fuselage of the present disclosure can be produced without deteriorating the quality of the base layer and resin layer. Furthermore, because the resin layer material does not impregnate the base layer, the fuselage of the present disclosure maintains a good balance of properties achieved by the combination of the resin layer and base layer.

[0023] The base layer member used to produce the body may be a pulp-containing sheet formed into the shape of the body. The base layer member may consist of only the part corresponding to the body, or may include the part corresponding to the body and parts corresponding to the edge or cap. The member that becomes the resin layer used to produce the body may be a sheet containing an imide resin that is molded into the shape of the body. The member that becomes the resin layer may consist of only the part that corresponds to the body, or may include the part that corresponds to the body and parts that correspond to the edge or cap.

[0024] (Layer structure of the body) The layer configuration of the body of the present disclosure may be a layer configuration in which a resin layer is disposed on one side of a base layer, a layer configuration in which resin layers are disposed on both sides of a base layer, etc. From the viewpoint of achieving sufficient chemical resistance, it is preferable that the resin layer is disposed at least on the front side of the body (the side that comes into contact with the external environment when the body is mounted on an electro-acoustic transducer).

[0025] The thickness of the body is not particularly limited, and can be set depending on the use, size, etc. of the electroacoustic transducer to which the body is applied. From the viewpoint of ensuring the rigidity of the body, the thickness of the body is preferably 0.1 mm or more, more preferably 0.15 mm or more, and even more preferably 0.2 mm or more. From the viewpoint of reducing the weight of the fuselage, the thickness of the fuselage is preferably 2.0 mm or less, more preferably 1.0 mm or less, and even more preferably 0.5 mm or less.

[0026] From the viewpoint of the balance between chemical resistance and acoustic properties, it is preferable that the value of X / Y calculated from the thickness X of the base material layer included in the fuselage and the thickness Y of the resin layer be equal to or greater than 1. In other words, it is preferable that the thickness of the resin layer included in the fuselage be equal to or smaller than the thickness of the base material layer.

[0027] From the viewpoint of maintaining good acoustic characteristics, the value of X / Y is preferably 1.5 or more, more preferably 2 or more, and even more preferably 5 or more. From the viewpoint of imparting sufficient chemical resistance to the body, the value of X / Y is preferably 20 or less, more preferably 15 or less, and even more preferably 10 or less.

[0028] The shape of the body is not particularly limited, and can be set depending on the application, size, etc. of the electroacoustic transducer to which the body is applied. The body may be generally conical in shape with an opening in the center.

[0029] <Diaphragm for electroacoustic transducer> The diaphragm for an electroacoustic transducer of the present disclosure includes the body described above. The diaphragm of the present disclosure may include an edge disposed around the periphery of the body or a cap disposed in the center of the body. The edge is a member that attaches the body to the electro-acoustic transducer. The cap is a member that prevents dust from entering the inside of the electro-acoustic transducer through the opening in the body.

[0030] The body and the edge included in the diaphragm may be separate members, or at least a portion of the body and the edge may be integrally formed. The state in which the body and the edge are at least partially molded as one piece includes (1) a state in which the body and the edge are completely molded as one piece, and (2) a state in which the body and the edge are partially molded as one piece. The state in which the body and the edge are completely integrally molded in (1) includes a state in which the body and the edge include a base layer and a resin layer in common. In this case, the body and the edge may have the same or different thicknesses. A preferred example of the (2) state in which the body and the edge are partially integrally molded is a state in which the resin layer of the body and the edge are integrally molded. For example, the body and the edge may both include a resin layer, but only the body may include a base layer. In this case, the edge may be made of only the resin layer, or may be made of the resin layer and a separate material. If the body and at least a part of the edge are integrally molded, it is advantageous in that it prevents the penetration of chemicals into the interface between the body and the edge, simplifies the manufacturing process, and improves product yield.

[0031] When the body and the edge included in the diaphragm are separate members, the material of the edge is not particularly limited and can be selected from commonly used materials such as rubber, resin, cloth, paper, etc. When the electro-acoustic transducer is used outdoors, the edge is preferably made of rubber or resin in consideration of properties such as weather resistance (especially heat resistance and cold resistance) and water resistance.

[0032] Examples of rubbers used as edge materials include ethylene-propylene rubber (EPDM), butyl rubber (IIR), acrylonitrile-butadiene rubber (NBR), and fluorinated silicone rubber (FVMQ).

[0033] The thickness of the edge is not particularly limited and can be selected depending on the size of the diaphragm, the purpose of use, etc. The thickness of the edge may be selected from the range of 15 μm to 5 mm, for example.

[0034] The method for joining the body and the edge is not particularly limited and can be selected taking into consideration the material of the edge, etc. For example, the body and the edge may be joined using an adhesive.

[0035] The body and cap included in the diaphragm may be separate members, or at least a portion of the body and cap may be integrally molded. The state in which the body and the cap are at least partially molded integrally includes (1) a state in which the body and the cap are completely molded integrally, and (2) a state in which the body and the cap are partially molded integrally. The state in which the body and the cap are completely integrally molded in (1) includes a state in which the body and the cap commonly include a base material layer and a resin layer. In this case, the body and the cap may have the same or different thicknesses. A preferred example of the partially integrally molded body and cap (2) is a body in which the resin layer of the body and the cap are integrally molded. For example, the body and the cap may both include a resin layer, but only the body may include a base material layer. In this case, the cap may consist of only the resin layer, or may consist of the resin layer and a separate member. If the body and at least a part of the cap are integrally molded, it is advantageous in terms of preventing seepage of chemical products at the interface between the body and the cap, simplifying the manufacturing process, and improving product yield.

[0036] When the body and cap included in the diaphragm are separate members, the material of the cap is not particularly limited and can be selected from commonly used materials such as rubber, resin, metal, etc. When the electroacoustic transducer is used outdoors, the material of the cap is preferably rubber, resin, or metal, taking into consideration properties such as weather resistance (particularly heat resistance and cold resistance) and water resistance.

[0037] Examples of rubber that can be used as the material for the cap include ethylene-propylene rubber (EPDM), butyl rubber (IIR), acrylonitrile-butadiene rubber (NBR), and fluorinated silicone rubber (FVMQ).

[0038] The thickness of the cap is not particularly limited and can be selected depending on the size of the diaphragm, the purpose of use, etc. The thickness of the cap may be selected from, for example, 15 μm to 2 mm.

[0039] The method for joining the body and the cap is not particularly limited and can be selected taking into consideration the material of the cap, etc. For example, the body and the cap may be joined using an adhesive.

[0040] The diaphragm of the present disclosure may further include a damping material. Damping material is a component attached to the diaphragm for the purpose of adjusting acoustic characteristics (increasing internal loss, improving distortion, etc.). Specific examples of the material for the damping material include resin, rubber, etc. Examples of resin include polyurethane, polystyrene, polyolefin, etc. The damping material may be in the form of foam, fiber, etc. The damping material is disposed, for example, on the entire surface or part of the back side of the diaphragm (the side that does not come into contact with the external environment when the diaphragm is mounted on an electroacoustic transducer). The damping material may be located behind either the fuselage or the edges, or behind both the fuselage and the edges.

[0041] <Configuration example of electroacoustic transducer> An example of the configuration of an electroacoustic transducer to which the fuselage of the present disclosure is applied is shown in Fig. 1. The electroacoustic transducer shown in Fig. 1 includes a fuselage 1, an edge 2 arranged around the fuselage 1, a cap 3 arranged in the center of the fuselage 1, a damper 4, a voice coil 5, and a frame 6.

[0042] 1, the body 1 and the edge 2 are depicted as being different members, but the body 1 and the edge 2 may be made of at least a portion of the same member. The edge 2 may have a convex shape when observed from the voice coil 5 side as shown in FIG. 1, or may have a concave shape when observed from the voice coil 5 side. If the edge 2 has a convex shape when observed from the voice coil 5 side, it is less susceptible to sudden changes in air pressure, water pressure, etc.

[0043] 1, the body 1 and the cap 3 are depicted as different members, but the body 1 and the cap 3 may be made of at least a portion of the same member. The cap 3 may have a convex shape when observed from the voice coil 5 side as shown in FIG. 1, or may have a concave shape when observed from the voice coil 5 side. If the cap 3 has a convex shape when observed from the voice coil 5 side, it is less susceptible to sudden changes in air pressure, water pressure, etc.

[0044] Although the body 1 is depicted in FIG. 1 as a flat member, the body 1 may be curved towards either the front or back side.

[0045] Fig. 2 is a partial enlarged view of the body 1 and the edge 2 of the electroacoustic transducer shown in Fig. 1. As shown in Fig. 2, the body 1 includes a resin layer a and a base layer b.

[0046] Fig. 3 shows a modification of the body 1 and the edge 2 shown in Fig. 2. As shown in Fig. 3, the body 1 and the edge 2 are integrally molded, and each includes a resin layer a and a base layer b.

[0047] Fig. 4 shows a modification of the body 1 and edge 2 shown in Fig. 2. As shown in Fig. 4, the body 1 and edge 2 are at least partially molded as a single unit. Specifically, the body 1 and edge 2 both include a resin layer a, but only the body 1 includes a base layer b.

[0048] FIG. 5 is a diagram showing a modified example of the body 1 and edge 2 shown in FIG. 2, in which a damping material c is arranged on the back side of the body 1 and edge 2. In FIG.

[0049] The frame, damper, voice coil and other members included in the electroacoustic transducer can be selected without particular limitation from appropriate members depending on the application, scale and the like of the electroacoustic transducer.

[0050] An electroacoustic transducer employing a body portion according to the present disclosure has excellent resistance to chemicals, making it suitable for applications that emit sound toward the outside of a vehicle cabin, such as a vehicle approach warning device. [Example]

[0051] Hereinafter, embodiments of the present disclosure will be described in detail with reference to examples, although the present disclosure is not limited to these examples. In the following examples, the measurements (calculated values) of sound velocity, internal loss, density and Young's modulus were carried out by the vibrating reed method.

[0052] <Evaluation of acoustic characteristics> (Preparation of test specimen) PEI films (Mitsubishi Chemical Corporation, Superior UT) with thicknesses of 38 μm, 75 μm, 100 μm, and 188 μm were attached to the adhesive (polyurethane adhesive)-coated surface of the papermaking sheet and hot-pressed to produce a laminate containing a resin layer containing PEI and a base layer containing pulp. This laminate was cut into pieces measuring 40 mm long and 5 mm wide to produce test pieces for Examples 1 to 4. The paper sheet used was made by beating wood pulp (NUKP) to a degree of beating of 25°SR and then making it into a flat sheet. As a test piece for Comparative Example 1, a PEI film (Superio UT, manufactured by Mitsubishi Chemical Corporation) having a thickness of 300 μm was cut into a size of 40 mm length×5 mm width and used. As a test piece for Comparative Example 2, a paper sheet cut into a size of 40 mm length x 5 mm width was used. The thickness of the paper sheet used to prepare the test specimen was adjusted so that the mass per unit area of ​​the test specimen was constant.

[0053] (Measurement of sound velocity and internal loss) The sound velocity (m / s) and internal loss (tan δ) of the test specimens were measured under conditions of 20°C and relative humidity of 65% (n=6). The results are shown in Table 1. It can be determined that the greater the sound velocity and internal loss, the better the acoustic characteristics will be when used as a diaphragm. [Table 1]

[0054] As shown in Table 1, the test pieces of Examples 1 to 4, which include a resin layer and a substrate layer, have both higher sound velocities and internal losses than the test piece of Comparative Example 2, which consists of only a resin layer. Among Examples 1 to 4, the test piece of Example 4 exhibits an internal loss equivalent to that of the test piece of Comparative Example 2 consisting of only a papermaking sheet. The above results suggest that by configuring the body of the diaphragm for an electroacoustic transducer to include a base layer containing pulp and a resin layer containing an imide-based resin, it is possible to achieve both improved chemical resistance and improved sound reproducibility.

[0055] (Measurement of density and Young's modulus) Density of the test piece (g / cm 3 The tensile strength (MPa) and Young's modulus (GPa) were measured at 20°C and a relative humidity of 65% (n=6). The results are shown in Table 2.

[0056] [Table 2]

[0057] As shown in Table 2, the test pieces of Examples 1 to 4, which include a resin layer and a base layer, have a lower density than the test piece of Comparative Example 2, which consists only of a resin layer. The above results suggest that by configuring the body of the diaphragm for an electroacoustic transducer to include a base layer containing pulp and a resin layer containing an imide-based resin, it is possible to achieve both improved chemical resistance and weight reduction.

[0058] As shown in Table 2, the test pieces of Examples 1 to 4, which include a resin layer and a base layer, have a larger Young's modulus than the test piece of Comparative Example 2, which consists only of a resin layer. The above results suggest that by configuring the body of the diaphragm for an electroacoustic transducer to include a base layer containing pulp and a resin layer containing an imide-based resin, it is possible to achieve both improved chemical resistance and improved strength.

[0059] <Evaluation of chemical resistance> The following test was conducted to verify whether chemical resistance is improved by configuring the body of a diaphragm for an electroacoustic transducer to include a base layer containing pulp and a resin layer containing an imide-based resin.

[0060] (Preparation of test specimen) A 50 μm or 75 μm thick PEI film (Mitsubishi Chemical Corporation, Superior UT) was attached to the adhesive (polyurethane adhesive) coated surface of the papermaking sheet and hot-pressed to produce a laminate containing a resin layer containing PEI and a base layer containing pulp. This laminate was cut into a circle with a diameter of 100 mm and then cut into four equal parts radially from the center. The resulting fan-shaped test pieces were used as test pieces for Examples 5 and 6. In Comparative Example 3, a paper sheet having a thickness of 0.62 mm was cut into a circle having a diameter of 100 mm, and the circle was cut into four equal parts radially from the center to obtain a fan-shaped test piece. In Comparative Examples 4 and 5, a PEI film (Superio UT, manufactured by Mitsubishi Chemical Corporation) having a thickness of 50 μm or 75 μm was cut into a circle having a diameter of 100 mm, and then cut into four equal parts radially from the center to obtain fan-shaped test pieces. The paper sheet used was made by beating wood pulp (NUKP) to a degree of beating of 25°SR and then making it into a flat sheet.

[0061] (Chemical impregnation) A chemical product (50 μL) was dropped onto one side of the test piece and left for 22 hours under conditions of 22-23°C and a relative humidity of 10-20%. For the test pieces of Examples 5 and 6, the chemical product was dropped onto the PEI film side. 22 hours after dropping, the test piece was washed with toluene and dried. Brake fluid, an oil-based chemical product, was used as the chemical product.

[0062] The mass A (g) of the test piece before the chemical product was dropped and the mass B (g) of the test piece after washing and drying were measured, and the difference C (g) and the rate of change D (%) were calculated using the following formula. The results are shown in Table 3. C=BA D = (C / A) × 100

[0063] [Table 3]

[0064] As can be seen from the results of Comparative Example 3, the test piece consisting of only a paper sheet showed a large change in mass when it was brought into contact with a chemical product. This is thought to be because oil-based chemical products are difficult to volatilize and tend to remain in the paper sheet. As can be seen from the results of Comparative Examples 4 and 5 and Examples 5 and 6, the mass change of the test piece containing the PEI film is sufficiently small when it comes into contact with chemical products. These results show that, among organic materials that are generally prone to phenomena such as swelling, deformation, adhesive peeling, and softening when in contact with chemical products, by selecting an imide resin as the material for the resin layer, it is possible to improve the chemical resistance of the body of the diaphragm for electroacoustic transducers. Furthermore, even though the test pieces of Examples 5 and 6 contained a paper sheet, the change in mass when they came into contact with chemical products was sufficiently small. The above results show that even if the body of the diaphragm for an electroacoustic transducer contains a base layer containing pulp, sufficient chemical resistance can be achieved by further containing a resin layer containing an imide-based resin.

[0065] The disclosure of Japanese Patent Application No. 2023-221906 is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards mentioned herein are incorporated by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. A body of a diaphragm for an electroacoustic transducer, comprising a base layer and a resin layer arranged on the surface of the base layer, the base layer being made of pulp obtained from plant raw materials molded into the shape of the body, and the resin layer being made of a sheet-like material made of an imide-based resin molded into the shape of the body, and the body being bonded together with an adhesive.

2. 2. The fuselage according to claim 1, wherein the thickness of the base material layer is 0.15 mm or more and 0.5 mm or less, and the thickness of the resin layer is 20 μm or more and 200 μm or less.

3. A fuselage as described in claim 1, wherein the base layer is made from paper.

4. A fuselage as described in claim 1, wherein the imide-based resin is polyetherimide.

5. A diaphragm for an electroacoustic transducer, comprising the body according to any one of claims 1 to 4.

6. 6. The diaphragm for an electroacoustic transducer according to claim 5, further comprising an edge disposed around the body, wherein a resin layer of the body and the edge are integrally molded.

7. A diaphragm for an electroacoustic transducer as described in Claim 6, wherein only the body includes the base material layer.

8. 6. The diaphragm for an electro-acoustic transducer according to claim 5, further comprising an edge disposed around the body, the body and the edge being separate members.

9. 6. The diaphragm for an electroacoustic transducer according to claim 5, further comprising a cap disposed at the center of said body, wherein said resin layer of said body and said cap are integrally molded.

10. A vehicle approach notification device comprising the fuselage described in claim 1.

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