Acoustic device comprising high density polyethylene film, electronic device comprising said acoustic device, method of manufacturing an acoustic device and use of high density polyethylene film in an acoustic device

Abstract

The present disclosure relates to acoustic devices that include high density polyethylene films. The present disclosure also relates to electronic devices that include acoustic devices, methods for making acoustic devices, and the use of high density polyethylene films in acoustic devices.

Description

[Technical Field]

[0001] FIELD OF THE INVENTION The present disclosure relates to an acoustic device comprising a high density polyethylene film. The present disclosure also relates to an electronic device comprising said acoustic device, a method for manufacturing an acoustic device, and the use of high density polyethylene film in an acoustic device. [Background technology]

[0002] Background technology Electronic products such as smartwatches include acoustic devices such as microphones. In acoustic devices, an acoustic transducer is held in a housing having an opening through which acoustic waves pass. During use of the electronic product, if water (including water vapor), dust (including fine dust), or other contaminants enter the housing through the opening, this can cause the acoustic device to malfunction and generate undesirable noise.

[0003] Therefore, the opening in the housing is typically covered with a membrane that allows sound to propagate through the housing while preventing water, dust, and / or other contaminants from entering the housing. For the membrane to function during a particular use in which external pressure is applied to the membrane, the membrane must be strong enough to allow sound to propagate through the membrane without significant sound transmission loss, yet not rupture or be damaged by the external pressure. The membrane must also be elastic, returning to or near its original position when the external pressure is removed. For example, external pressure may be applied to an acoustic device during use, such as when submerged in water.

[0004] Membranes are typically porous to prevent the intrusion of water vapor and / or fine dust particles. However, when non-porous membranes are used in acoustic devices, the thickness of the membrane becomes a more important factor in sound propagation because there are no interconnected pores through which sound can pass. Thicker membranes typically suffer from sound propagation losses more than thinner membranes. This is especially true for dense (non-porous) membranes.

[0005] Currently, acoustic devices use PTFE membranes to prevent the intrusion of water, dust, and / or other contaminants. Typically, non-porous PTFE membranes strong enough for practical use under external pressure require relatively thick membranes. However, the required thickness of non-porous PTFE can adversely affect sound propagation, resulting in significant sound transmission loss.

[0006] Therefore, there is a need for an improved membrane for acoustic devices that is strong enough to withstand external pressure and that prevents the ingress of water (including water vapor), dust (including fine dust), and other contaminants without causing significant sound transmission loss.

[0007] The present disclosure solves the above problems. Summary of the Invention

[0008] Abstract In a first aspect, an acoustic device includes a housing including at least one opening communicating with the outside of the acoustic device, an acoustic transducer disposed within the housing, and a high-density polyethylene film covering the at least one opening communicating with the outside of the acoustic device, wherein the high-density polyethylene film has a first direction and a second direction, the second direction being perpendicular to the first direction, the high-density polyethylene film having a thickness of about 0.5 μm to about 3.0 μm, the first direction and the second direction being perpendicular to the thickness direction, and the high-density polyethylene film having an average mass per area of ​​about 0.4 g / m 2 ~about 3g / m 2 wherein the high-density polyethylene film has a geometric mean five-point modulus of elasticity of at least about 1500 MPa, and the high-density polyethylene film is formed from a polyethylene polymer comprising ultra-high molecular weight polyethylene (UHMWPE).

[0009] The film is formed from a polyethylene polymer including ultra-high molecular weight polyethylene, and (i) has a thickness of about 0.5 μm to about 3.0 μm, and (ii) has an average mass per area of ​​about 0.4 g / m 2 ~about 3g / m2 It has been surprisingly discovered that a high-density polyethylene film having (i) a tensile strength of 0.1 MPa and (ii) a geometric mean five-point elastic modulus of at least about 1500 MPa possesses an ideal balance of properties for use in acoustic devices. Specifically, when used to cover an opening in an acoustic device, this high-density polyethylene film effectively prevents water (including water vapor), dust (including fine dust), and other contaminants (collectively referred to herein as "contaminants") from entering the acoustic device. Furthermore, the high-density polyethylene film has high strength, allowing it to withstand external pressure without damage and / or rupture. Additionally, this high-density polyethylene film does not result in significant sound transmission loss.

[0010] Specifically, the thickness is about 0.5 μm to about 3.0 μm, and the average mass per area is about 0.4 g / m 2 ~about 3g / m 2 A high-density polyethylene membrane having a thickness of about 0.5 μm to about 3.0 μm ensures that the membrane does not introduce significant sound transmission loss. Typically, thicker membranes have a higher sound transmission loss compared to thinner membranes. This is particularly true for dense (or non-porous) membranes. Thus, membranes having a thickness of about 0.5 μm to about 3.0 μm are beneficial for sound transmission. Similarly, a membrane with a higher average mass per area typically has a higher sound transmission loss compared to a membrane with a lower average mass per area. Again, this is particularly true for dense (or non-porous) membranes. Thus, a membrane with an average mass per area of ​​about 0.4 g / m 2 ~about 3g / m 2 A membrane with a thickness of 1000 Å is beneficial for sound transmission.

[0011] High density polyethylene films having a geometric mean five-point modulus of at least about 1500 MPa exhibit good strength properties and have a thickness of less than 3.0 μm and an average mass per area of ​​3 g / m 2 It has been found that a geometric mean five-point modulus of less than 1000 kJ / cm can be achieved for high-density polyethylene membranes. This geometric mean five-point modulus ensures that the membrane can withstand external pressure.

[0012] Compared to state-of-the-art membranes for acoustic devices, such as PTFE membranes, high-density polyethylene membranes with the above characteristics offer an improved balance of properties for use as acoustic covers. Specifically, when comparing high-density polyethylene membranes and high-density PTFE membranes of the same thickness, the high-density polyethylene membrane generally exhibits improved properties, as indicated by the geometric mean five-point modulus. To achieve the same or comparable mechanical strength properties, the high-density PTFE membrane must be thicker than the high-density polyethylene membrane, which adversely affects sound transmission loss. Furthermore, PTFE has a skeletal density approximately twice that of polyethylene, which further adversely affects sound transmission loss in high-density membranes.

[0013] In one embodiment, the high-density polyethylene membrane can have an average five-point modulus in a first in-plane direction of at least about 1500 MPa. In another embodiment, the high-density polyethylene membrane can have an average five-point modulus in a second, orthogonal in-plane direction of at least about 1000 MPa. The geometric mean five-point modulus is the square root of the product of the average five-point modulus in the first direction and the average five-point modulus in the second direction. Thus, the average five-point modulus in the first direction and the average five-point modulus in the second direction are related to the geometric mean five-point modulus, and these values ​​result in excellent mechanical properties for the high-density polyethylene membrane.

[0014] In one embodiment, the high-density polyethylene membrane can have a mean matrix tensile strength (MTS) in a first in-plane direction of at least about 200 MPa. In another embodiment, the high-density polyethylene membrane can have a mean matrix tensile strength (MTS) in a second, orthogonal in-plane direction of at least about 150 MPa. In another embodiment, the high-density polyethylene membrane can have a geometric mean matrix tensile strength (MTS) of at least about 175 MPa. The geometric mean matrix tensile strength is the square root of the product of the mean matrix tensile strength (MTS) in a first direction and the mean matrix tensile strength (MTS) in a second direction. Thus, the mean matrix tensile strength (MTS) in a first direction and the mean matrix tensile strength (MTS) in a second direction are related to the geometric mean matrix tensile strength (MTS), and these values ​​result in superior mechanical properties for the high-density polyethylene membrane.

[0015] In one embodiment, the high density polyethylene membrane has a water vapor permeability coefficient of about 0.0001 g-mm / m 2 / day ~ approx. 0.3g-mm / m 2 In this case, the high-density polyethylene film is almost impermeable to water vapor, so that the acoustic device can be protected from damage by water.

[0016] In one embodiment, the high density polyethylene film has a density of at least about 0.88 g / cm 3 It can be.

[0017] In one embodiment, the high density polyethylene film may have substantially no measurable airflow, which helps prevent contaminants from entering the acoustic device.

[0018] In one embodiment, the acoustic device has an average delta transmission loss (dB) of less than about 3 dB, where the average delta transmission loss is calculated by subtracting the measured transmission loss before the pressure test from the measured transmission loss 24 hours after the pressure test, where the pressure test is an open hole load of 1 bar, and the sound frequency is 3 KHz.

[0019] In one embodiment, the high-density polyethylene film has a thickness of about 0.7 μm to about 2.8 μm, and in some cases, about 0.8 μm to 2.4 μm. An excessively thin film may lack mechanical strength.

[0020] In one embodiment, the high density polyethylene film has an average mass per area of ​​about 0.6 g / m 2 ~Approx. 2.8g / m 2 , in some cases, about 0.7 g / m 2 ~approx. 2.4g / m 2 It can be.

[0021] In one embodiment, the acoustic device may further include a reinforcing plate for providing support to the high-density polyethylene membrane. The reinforcing plate may be selected from a perforated metal plate, a woven fabric, a non-woven fabric, a mesh, a net, a sponge, a foam, and a porous body made of metal or resin. The function of the reinforcing plate is to provide mechanical support to the membrane when an external pressure is applied to the acoustic device. The reinforcing plate may cover at least one opening in the housing. The reinforcing plate may be disposed between the high-density polyethylene membrane and the acoustic transducer. The acoustic device may have an average delta transmission loss (dB) of less than about 3 dB, where the average delta transmission loss is calculated by subtracting the measured transmission loss before the pressure test from the measured transmission loss 24 hours after the pressure test, where the pressure test is at a load of 10 bar (with the reinforcing plate) and the acoustic frequency is 3 kHz.

[0022] In one embodiment, the acoustic device may further include a coating layer on the surface of the high-density polyethylene film. The high-density polyethylene film may be disposed between the coating layer and the acoustic transducer. Alternatively, the coating layer may be disposed between the high-density polyethylene film and the acoustic transducer, or may coexist on both sides of the high-density polyethylene film. The coating layer may include one or more of the group consisting of metal, carbon, and electronically conductive polymer. The coating layer may be an antistatic layer. The antistatic layer may include an antistatic component. The antistatic component may be selected from one or more of the group consisting of metal, carbon, and electronically conductive polymer.

[0023] In one embodiment, the high-density polyethylene film can further include an additive. The additive can be selected from one or more of the group consisting of metal, carbon, and electronically conductive polymers. The additive can be present in the high-density polyethylene film. The additive can be an antistatic component. The antistatic component can be selected from one or more of the group consisting of metal, carbon, and electronically conductive polymers. In one embodiment, the acoustic transducer can be positioned within the housing such that the opening directs sound to the acoustic transducer.

[0024] In one embodiment, the ultra-high molecular weight polyethylene polymer has an average molecular weight of from 1,000,000 g / mol to 10,000,000 g / mol. Optionally, the ultra-high molecular weight polyethylene polymer has an average molecular weight of from 2,000,000 g / mol to 10,000,000 g / mol.

[0025] The method for producing the high-density polyethylene film is not particularly limited. In one embodiment, the high-density polyethylene film can be produced by the following method: dissolving a polyethylene polymer in a solvent to form a solution, forming the solution into a tape at a temperature above the dissolution temperature of the polyethylene polymer, cooling the tape to a temperature below the dissolution temperature to gel the tape, removing the solvent from the gelled tape, and biaxially stretching the gelled tape at a temperature above the melting temperature to form a high-density polyethylene film.

[0026] In one embodiment, a high-density polyethylene film can be produced by a process of: providing a paste comprising a polyethylene polymer and a lubricant; forming the paste into a tape; removing the lubricant from the tape to form a dry polyethylene tape; compressing the dry polyethylene tape below the melting temperature of the polyethylene polymer; and stretching the polyethylene tape in at least two directions at a temperature above the melting temperature of the polyethylene polymer to form a high-density polyethylene film.

[0027] In one embodiment, the acoustic device can be a microphone or a speaker.

[0028] In a second aspect, an electronic device includes the acoustic device of the present disclosure. The electronic device can be a smartwatch, a mobile phone, a buzzer, a voice recorder, or any other device in which an acoustic device can find use. In one embodiment, a smartwatch includes the acoustic device of the present disclosure.

[0029] In a third aspect, there is provided a method of manufacturing an acoustic device of the present disclosure, the method comprising the steps of: (i) providing a housing, an acoustic transducer, and a high-density polyethylene film, wherein the housing includes at least one opening communicating with an exterior of the acoustic device; (ii) disposing the acoustic transducer within the housing; and (iii) covering at least one opening of the housing that communicates with the exterior of the acoustic device with the high-density polyethylene film.

[0030] In one embodiment, the method of manufacturing an acoustic device can further include forming a high density polyethylene film by the process described above.

[0031] In one embodiment, the method for manufacturing an acoustic device can further include the step of securing the high-density polyethylene film to the housing, for example, using an adhesive. Optionally, the method for manufacturing an acoustic device can further include the step of hermetically sealing the high-density polyethylene film to the housing, thereby forming a waterproof seal and thus preventing the ingress of contaminants into the acoustic device through the interface between the high-density polyethylene film and the housing.

[0032] In one embodiment, the method for manufacturing an acoustic device can further include providing a stiffening plate and disposing the stiffening plate to cover at least one opening in the housing that communicates with the exterior of the acoustic device, thereby providing support for the high-density polyethylene film. In one embodiment, the high-density polyethylene film is disposed between the opening in the housing and the stiffening plate.

[0033] In one embodiment of the method for manufacturing an acoustic device, the step of providing a high-density polyethylene film can include providing a high-density polyethylene film having a coating layer on a surface of the high-density polyethylene film. In one embodiment, the high-density polyethylene film is disposed between the coating layer and the acoustic transducer. In other embodiments, the coating layer can be disposed between the high-density polyethylene film and the acoustic transducer, or can coexist on both sides of the high-density polyethylene film. The coating layer can be as described above. For example, the coating layer can be an antistatic layer, e.g., the antistatic layer can include an antistatic component. In an embodiment, the antistatic layer can be disposed between the coating layer and the acoustic transducer, between the high-density polyethylene film and the acoustic transducer, or coexist on both sides of the high-density polyethylene film.

[0034] In one embodiment of the method for manufacturing an acoustic device, the step of providing a high-density polyethylene film can include providing a high-density polyethylene film containing an additive. The additive can be as described above. The additive can be present in the high-density polyethylene film. For example, the additive can be an antistatic component.

[0035] In a fourth aspect, there is provided a use of the high-density polyethylene film of the present disclosure in an acoustic device, which can be used to cover an opening in a housing to prevent the intrusion of water (including water vapor), dust (including fine dust), and other contaminants into the acoustic device.

[0036] The present disclosure also provides an acoustic device comprising: a housing including at least one opening communicating with the outside of the acoustic device; an acoustic transducer, wherein the acoustic transducer is disposed within the housing; and a high-density polyethylene film covering the at least one opening communicating with the outside of the acoustic device, wherein the high-density polyethylene film has a first direction and a second direction, the second direction being perpendicular to the first direction, the high-density polyethylene film having a thickness of about 0.5 μm to about 7.0 μm, the first direction and the second direction being perpendicular to the thickness direction, and the high-density polyethylene film having an average mass per area of ​​about 0.4 g / m. 2 ~about 7g / m 2 The acoustic device is provided, wherein the high-density polyethylene film has a geometric mean five-point modulus of elasticity of at least about 1500 MPa and is formed from a polyethylene polymer including ultra-high molecular weight polyethylene. The high-density polyethylene film can have a thickness of about 0.5 μm to about 6 μm, or about 0.5 μm to about 5 μm, or about 0.5 μm to about 4 μm.

[0037] The above-described embodiments should not be construed as limiting or narrowing the scope of the inventive concepts otherwise provided by this disclosure. While multiple embodiments are disclosed, other embodiments will become apparent to those skilled in the art from the following description and drawings. Accordingly, the description and drawings should be considered illustrative and not restrictive. [Brief explanation of the drawings]

[0038] BRIEF DESCRIPTION OF THE DRAWINGS [Figure 1] Drawing 1 (FIG. 1) is a schematic diagram of an acoustic device according to an embodiment of the present disclosure.

[0039] [Figure 2] Drawing 2 (FIG. 2) is a schematic diagram of the acoustic device of FIG. 1 further including a perforated stiffener plate, according to an embodiment of the present disclosure.

[0040] [Figure 3]Drawing 3 (FIG. 3) is a schematic diagram of the acoustic device of FIG. 1 further including an antistatic layer, according to an embodiment of the present disclosure.

[0041] [Figure 4] Drawing 4 (FIG. 4) shows a schematic of an exemplary setup for pressure testing.

[0042] [Figure 5] FIG. 5 shows a scanning electron micrograph of a high density polyethylene film with a physical vapor deposition tantalum layer that can be used in the acoustic devices of the present disclosure.

[0043] [Figure 6] Figure 6 (Figure 6) shows a plot of the sound transmission loss for ultra-high molecular weight polyethylene without a tantalum layer (deposition time 0 seconds) and for samples with a tantalum layer deposited for 1 second, 2 seconds, and 5 seconds, and no reinforcing plate at the initial time point.

[0044] It should be noted that the accompanying drawings referred to herein are not necessarily drawn to scale and may be exaggerated for purposes of illustrating various aspects of the present disclosure, and in that regard, they should not be construed as limiting. DETAILED DESCRIPTION OF THE INVENTION

[0045] Detailed Description The present disclosure provides an acoustic device comprising: a housing including at least one opening communicating with the outside of the acoustic device; an acoustic transducer, wherein the acoustic transducer is disposed within the housing; and a high-density polyethylene film covering the at least one opening communicating with the outside of the acoustic device, wherein the high-density polyethylene film has a first direction and a second direction, the second direction being perpendicular to the first direction, the high-density polyethylene film having a thickness of about 0.5 μm to about 3.0 μm, the first direction and the second direction being perpendicular to the thickness direction, and the high-density polyethylene film having an average mass per area of ​​about 0.4 g / m.2 ~about 3g / m 2 wherein the high-density polyethylene film has a geometric mean five-point modulus of elasticity of at least about 1500 MPa, and the high-density polyethylene film is formed from a polyethylene polymer including ultra-high molecular weight polyethylene.

[0046] As described above, it has been surprisingly discovered that such a high-density polyethylene film has an ideal balance of properties for use in acoustic devices. Specifically, by using this high-density polyethylene film to cover the opening of an acoustic device, it is possible to effectively prevent water (including water vapor), dust (including fine dust), and other contaminants from entering the acoustic device. Furthermore, the high-density polyethylene film has high strength, allowing it to withstand external pressure without damage and / or rupture. Furthermore, the high-density polyethylene film does not result in significant sound transmission loss.

[0047] [Components of acoustic devices]

[0048] The acoustic device includes a housing, an acoustic transducer, and a high-density polyethylene membrane.

[0049] The housing is hollow and includes an acoustic cavity, and the acoustic transducer is housed within the housing. The housing also has at least one opening communicating with the exterior of the acoustic device, through which sound passes and is received by the acoustic transducer. The sound passes through the acoustic cavity within the housing to reach the acoustic transducer.

[0050] The material from which the housing is made is not particularly limited and can be any suitable material known in the art, such as a resin, a polymer, a metal, etc. The housing protects the acoustic transducer from contaminants. Any suitable housing known in the art can be used in the present disclosure.

[0051] The acoustic transducer is not particularly limited, and its function can be to convert sound into an electrical signal. Any suitable acoustic transducer known in the art can be used in the present disclosure.

[0052] At least one opening of the housing that communicates with the exterior of the acoustic device is covered by a high-density polyethylene film. In one embodiment, the high-density polyethylene film completely covers the at least one opening to prevent the intrusion of contaminants. Thus, the high-density polyethylene film, in combination with the housing, protects the acoustic transducer from contaminants. This helps improve the performance of the acoustic device, as contaminants affect the performance of the acoustic transducer.

[0053] The high-density polyethylene membrane may be secured to the housing to cover the at least one opening. The membrane may form an airtight seal with the housing to cover the at least one opening. The airtight seal ensures that water and other contaminants cannot penetrate into the acoustic device through the seal. The seal between the housing and the high-density polyethylene membrane may be formed by an adhesive layer. The adhesive is not particularly limited, and any suitable adhesive known in the art may be used.

[0054] Drawing 1 (FIG. 1) shows an example of an acoustic device (100) including a housing (110) with an opening (112) communicating with the exterior of the device (101), an acoustic transducer (120), and a high-density polyethylene membrane (130) covering the opening. The high-density polyethylene membrane completely covers the opening and is secured to the housing by adhesive (140). The acoustic transducer (120) is disposed within the housing (114). In the illustrated embodiment, the acoustic transducer (120) is supported on a device body (116) that is disposed within the housing.

[0055] The acoustic device may further include a reinforcing plate for providing support to the polyethylene film. The reinforcing plate may be selected from a perforated metal plate, a woven fabric, a nonwoven fabric, a mesh, a net, a sponge, a foam, and a porous body made of metal or resin. The reinforcing plate may be a perforated metal plate.

[0056] The function of the stiffener plate is to act as a support for the high-density polyethylene membrane, pushing the membrane toward the inside of the acoustic device or housing when external pressure is applied to the acoustic device. Typically, the high-density polyethylene membrane is disposed between the opening of the housing and the stiffener plate, such that when external pressure is applied to the acoustic device, the high-density polyethylene membrane deforms toward the inside of the housing and presses against the stiffener plate. Thus, the stiffener plate provides mechanical support to the membrane and prevents further deformation. When no external pressure is applied to the acoustic device, the stiffener plate is not in contact with the high-density polyethylene membrane. The stiffener plate can be spaced from the high-density polyethylene membrane by a distance of at least about 30 μm. For example, this distance can be about 30 μm to about 100 μm, about 30 μm to 70 μm, or about 50 μm.

[0057] The stiffener plate can be porous or can include holes or openings through the thickness of the plate so that it does not significantly affect sound transmission, hi one embodiment, there is little or no sound transmission loss caused by the stiffener plate.

[0058] An example of a stiffening plate in an acoustic device is shown in Figure 2 (Figure 2). In Figure 2, the stiffening plate (210) is a perforated metal plate. When external pressure is applied, the high-density polyethylene membrane deforms toward the inside of the acoustic device and presses against the stiffening plate. Thus, the stiffening plate provides mechanical support to the high-density polyethylene membrane.

[0059] A coating layer can be provided on the surface of the high-density polyethylene film. The coating layer can include one or more of the group consisting of metal, carbon, and electronically conductive polymer. Preferred metals can be aluminum or tantalum. Preferred carbon can be graphite, carbon nanotubes, graphene, or carbon black. Preferred electronically conductive polymers can be poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS).

[0060] The coating layer can improve one or both of the gas and moisture permeability of the high-density polyethylene membrane, for example, by reducing the membrane's gas and / or moisture permeability. Such a coating layer can comprise a metal, e.g., a physical vapor deposition (PVD) metal layer such as aluminum or tantalum. The thickness of such a layer can be in the range of 10 to 150 nanometers, preferably in the range of 20 to 100 nanometers, e.g., 20 nanometers or 35 nanometers. The PVD layer can be deposited by known methods, such as the method disclosed in "Metallization of polymers and composites: State-of-the-art approaches," Materials & Design, 221, (2022) 110958.

[0061] The high-density polyethylene film can be disposed between the coating layer and the acoustic transducer, with the coating layer facing the exterior of the device and the high-density polyethylene film facing the interior of the device. The coating layer can facilitate adhesion of the high-density polyethylene film to the housing with an adhesive.

[0062] The coating layer may also improve the durability of the high-density polyethylene film, for example, by reducing degradation due to ultraviolet light. Such coating layers may include one or both of a metal and carbon. Preferred metals and carbons may be of the type described above for the coating layer.

[0063] The coating layer can also improve the handleability of the high-density polyethylene film, for example, when the coating layer contains an antistatic component. Thus, the high-density polyethylene film can be a static-dissipative film. Thus, the coating layer can be an antistatic layer. Thus, the static-dissipative film can include a high-density polyethylene film and an antistatic layer. The antistatic layer can include an antistatic component. The antistatic component can be an electronically conductive component. The antistatic component can be selected from one or more of the group consisting of metals, carbon, and electronically conductive polymers. Preferred metals, carbon, and electronically conductive polymers can be the same types as those described above for the coating layer. The thickness of the antistatic layer can be in the range of 10 to 150 nanometers, preferably in the range of 20 to 100 nanometers, e.g., 20 nanometers or 35 nanometers. The antistatic layer can account for 35 wt% or less, preferably 25 wt% or less, of the total mass of the static-dissipative film, i.e., the combined mass of the antistatic layer and the high-density polyethylene film. Maintaining the antistatic layer at 35 wt% or less of the total mass of the static-dissipative film ensures that the acoustic properties of the film are not substantially affected. The antistatic layer can be present in the range of 1-35 wt% of the total mass of the static-dissipative film, or in the range of 5-25 wt% of the total mass of the static-dissipative film.

[0064] The additive can be incorporated into the high-density polyethylene film, for example, within the bulk of the high-density polyethylene film. The additive can be one or more of the group consisting of metal, carbon, and electronically conductive polymer. The additive can be an antistatic component, such as an electrically conductive component. Thus, the high-density polyethylene film can include polyethylene and an antistatic component. Thus, the high-density polyethylene film can be a static dissipative film. The antistatic component can be selected from one or more of the group consisting of metal, carbon, and electronically conductive polymer. Preferred metal, carbon, and electronically conductive polymers can be of the type described above for the coating layer. The antistatic component can be present in an amount of up to 35 wt% of the total mass of the high-density polyethylene film, such as the antistatic component and polyethylene, for example, in a range of 1 to 35 wt% of the total mass of the high-density polyethylene film, or in a range of 5 to 25 wt% of the total mass of the high-density polyethylene film.

[0065] The static dissipative film has a lower surface resistivity than a high-density polyethylene film that does not contain an antistatic component and / or has no antistatic layer on the surface. The presence of the antistatic component and / or antistatic layer reduces static charge on the film.

[0066] Drawing 3 (FIG. 3) shows an acoustic device (100) including a coating layer (150) on a surface of a high-density polyethylene film (130). The high-density polyethylene film (130) can be disposed between the coating layer (150) and the acoustic transducer (120). The high-density polyethylene film can have opposing first and second surfaces. The coating layer can be disposed on the first surface of the high-density polyethylene film, which can face the exterior of the housing (114). The second surface of the high-density polyethylene film, if present, can be disposed on the stiffener plate (210) and can face the acoustic transducer (120). The coating layer (150) can be secured to the housing (114) by adhesive (140), as described for the embodiment of FIG. 1.

[0067] In some embodiments, the acoustic device is a microphone or a speaker. In one embodiment, the acoustic device is a microphone.

[0068] [High-density polyethylene film]

[0069] A high-density polyethylene membrane covers at least one opening in the housing. To function most effectively as a barrier to contaminants, the membrane should be non-porous. In the context of this disclosure, the term "high-density" refers to a non-porous or substantially non-porous polyethylene membrane, meaning that there are substantially no pores that would allow fluid communication between a first major surface of the membrane and a second major surface opposite the first surface. For example, a membrane that has an air permeability between one major surface and the other major surface below a detectable level, as measured using the ATEQ test described herein, is said to be a high-density or non-porous membrane. A "high-density" membrane in the context of this invention is one having a membrane density of at least about 0.88 g / cm. 3 It can also mean that.

[0070] The high-density polyethylene film has a first direction and a second direction, the second direction being perpendicular to the first direction. The high-density polyethylene film has a thickness of about 0.5 μm to about 3.0 μm, and the first direction and the second direction are each perpendicular to the thickness direction. A film thickness of about 0.5 μm to about 3.0 μm is beneficial for sound transmission. This is because, generally, the thinner the film, the better the sound transmission through the film. For example, a film with a thickness of 5 μm will generally have a higher sound transmission loss than an identical film except that it is thinner than about 3.0 μm.

[0071] The high density polyethylene film has a thickness of at least 0.5 μm. An excessively thin film has poor mechanical and strength properties.

[0072] In some embodiments, the high density polyethylene film has a thickness of about 0.6 μm to about 3.0 μm, or about 0.7 μm to about 2.9 μm, or about 0.7 μm to about 2.8 μm, or about 0.7 μm to about 2.7 μm, or about 0.7 μm to about 2.6 μm, or about 0.7 μm to about 2.5 μm, or about 0.8 μm to about 2.4 μm, or about 0.8 μm to about 2.3 μm, Alternatively, the thickness may be about 0.8 μm to about 2.2 μm, about 0.8 μm to about 2.1 μm, about 0.8 μm to about 2.0 μm, about 0.8 μm to about 1.9 μm, about 0.8 μm to about 1.8 μm, about 0.8 μm to about 1.7 μm, about 0.9 μm to about 1.6 μm, about 0.9 μm to about 1.6 μm, or about 1.0 μm to about 1.5 μm. Such a thickness provides excellent sound transmission properties.

[0073] Film thickness is measured as indicated in the test methods described herein.

[0074] The key to sound transmission loss is the average mass per area of ​​the membrane. High density polyethylene membranes have an average mass per area of ​​about 0.4 g / m 2 ~about 3g / m 2 The average mass per area of ​​the membrane is about 0.4 g / m 2 ~about 3g / m 2 This is because the lower the average mass per area of ​​the membrane, the lower the sound transmission loss. For example, an average mass per area of ​​5 g / m 2 The average mass per area of ​​the membrane is 3g / m 2 The sound transmission loss will generally be higher compared to an identical membrane that differs only by less than 1000 MPa.

[0075] In some embodiments, the high density polyethylene film has an average mass per area of ​​about 0.5 g / m 2 ~about 3g / m 2 , or about 0.6 g / m 2 ~approx. 2.9g / m 2 , or about 0.7 g / m 2 ~Approx. 2.8g / m 2 , or about 0.6 g / m 2 ~Approx. 2.7g / m 2 , or about 0.6 g / m2 ~Approx. 2.6g / m 2 , or about 0.6 g / m 2 ~about 2.5g / m 2 , or about 0.7 g / m 2 ~approx. 2.4g / m 2 , or about 0.7 g / m 2 ~Approx. 2.3g / m 2 , or about 0.7 g / m 2 ~Approx. 2.2g / m 2 , or about 0.7 g / m 2 ~Approx. 2.1g / m 2 , or about 0.7 g / m 2 ~about 2g / m 2 , or about 0.7 g / m 2 ~approx. 1.9g / m 2 , or about 0.7 g / m 2 ~Approx. 1.8g / m 2 , or about 0.7 g / m 2 ~Approx. 1.7g / m 2 , or about 0.8 g / m 2 ~Approx. 1.6g / m 2 , or about 0.9 g / m 2 ~Approx. 1.5g / m 2 Such an average mass per area of ​​the membrane provides excellent sound transmission properties.

[0076] The average mass per area of ​​the membrane is measured as shown in the test methods described herein. For a given polyethylene density, the average mass per area is related to the thickness of the membrane.

[0077] High-density polyethylene membranes have a geometric mean five-point modulus of at least about 1500 MPa. This ensures that the membrane has adequate strength properties to function effectively as an acoustic cover. A geometric mean five-point modulus of at least about 1500 MPa ensures that the membrane will not deform excessively under external pressure. Specifically, the membrane is strong enough to withstand external pressures, such as those experienced when immersed in water. Membranes with excessively low geometric mean five-point modulus have poor mechanical and strength properties.

[0078] Additionally, the membrane should be elastic so that when the external pressure is released, the membrane can deform back to its original position or a position close to its original position without being permanently stretched.

[0079] In some embodiments, the high-density polyethylene membrane may have a geometric mean five-point modulus of at least about 1550 MPa, or at least about 1600 MPa, or at least about 1700 MPa, or at least about 1800 MPa, or at least about 1900 MPa, or at least about 2000 MPa, or at least about 2100 MPa, or at least about 2200 MPa, or at least about 2300 MPa, or at least about 2400 MPa, or at least about 2500 MPa. The high-density polyethylene film can have a geometric mean five-point modulus of about 1500 MPa to about 5000 MPa, or about 1550 MPa to about 5000 MPa, or about 1600 MPa to about 4500 MPa, or about 1700 MPa to about 4500 MPa, or about 1800 MPa to about 4500 MPa, or about 1900 MPa to about 4500 MPa, or about 2000 MPa to about 4500 MPa, or about 2100 MPa to about 4000 MPa, or about 2200 MPa to about 4000 MPa, or about 2300 MPa to about 4000 MPa.

[0080] The geometric mean five-point modulus is defined as the square root of the product of the mean five-point modulus in a first direction and the mean five-point modulus in a second direction.

number

[0081] Thus, the average five-point modulus in a first direction and the average five-point modulus in a second direction are related to the geometric mean five-point modulus.

[0082] In some embodiments, the high-density polyethylene film can have an average five-point modulus in a first direction of at least about 1500 MPa, or at least about 1750 MPa, or at least about 2000 MPa, or at least about 2250 MPa, or at least about 2500 MPa, or at least about 2750 MPa, or at least about 3000 MPa, or from about 1500 MPa to about 4500 MPa, or from about 1750 MPa to about 4500 MPa, or from about 2000 MPa to about 4500 MPa, or from about 2250 MPa to about 4500 MPa, or from about 2500 MPa to about 4500 MPa.

[0083] In some embodiments, the high-density polyethylene film can have an average five-point modulus in the second direction of at least about 1000 MPa, or at least about 1250 MPa, or at least about 1500 MPa, or at least about 2000 MPa, or from about 1000 MPa to about 3500 MPa, or from about 1250 MPa to about 3500 MPa, or from about 1500 MPa to about 3500 MPa, or from about 1750 MPa to about 3500 MPa, or from about 2000 MPa to about 3500 MPa.

[0084] The average 5-point modulus in each direction is calculated as set forth in the test methods described herein.

[0085] High-density polyethylene films are formed from polyethylene polymers, including ultra-high molecular weight polyethylene. In the context of the present disclosure, ultra-high molecular weight polyethylene refers to polyethylene having an average molecular weight of about 1,000,000 g / mol to about 10,000,000 g / mol. The average molecular weight may refer to the viscosity-average molecular weight calculated from the intrinsic viscosity, as described, for example, in Pure Appl. Chem. 2020; 92(9):1469-1483. In some embodiments, the ultra-high molecular weight polyethylene polymer has an average molecular weight of about 1,500,000 to about 10,000,000 g / mol, or about 2,000,000 g / mol to about 10,000,000 g / mol, or about 4,000,000 g / mol to about 8,000,000 g / mol.

[0086] In some embodiments, the high-density polyethylene membrane can have an average matrix tensile strength (MTS) in a first direction of at least about 200 MPa, or from about 200 MPa to about 700 MPa, or from about 225 MPa to about 600 MPa, or from about 250 MPa to about 550 MPa.

[0087] In some embodiments, the high-density polyethylene membrane can have an average matrix tensile strength (MTS) in the second direction of at least about 150 MPa, or from about 150 MPa to about 600 MPa, or from about 175 MPa to about 550 MPa, or from about 200 MPa to about 500 MPa.

[0088] In some embodiments, the high-density polyethylene membrane can have a geometric mean matrix tensile strength (MTS) of at least about 175 MPa, or from about 175 MPa to about 600 MPa, or from about 200 MPa to about 550 MPa, or from about 200 MPa to about 500 MPa.

[0089] Geometric mean matrix tensile strength (MTS) = square root of the product of the average MTS in a first direction and the average MTS in a second direction.

number

[0090] The average matrix tensile strength in each direction is calculated as indicated in the test methods described herein.

[0091] In some embodiments, the high density polyethylene membrane has a water vapor permeability coefficient of about 0.0001 g-mm / m 2 / day ~ approx. 0.3g-mm / m 2 / day, or approximately 0.0001 g-mm / m 2 / day ~ approx. 0.2g-mm / m 2 / day, or approximately 0.0001 g-mm / m 2 / day ~ approx. 0.1g-mm / m 2 / day. In some embodiments, the high density polyethylene membrane is substantially water impermeable.

[0092] The water vapor transmission coefficient is measured as set forth in the test methods described herein.

[0093] In some embodiments, the high density polyethylene film has a density of at least about 0.88 g / cm 3 , or at least about 0.89 g / cm 3 , or at least about 0.90 g / cm 3 , or at least about 0.91 g / cm 3 , or at least about 0.92 g / cm 3 , or at least about 0.93 g / cm 3 , or at least about 0.94 g / cm 3 In some embodiments, the high density polyethylene film can have a density of about 0.88 g / cm 3 ~Approx. 1.0g / cm 3 , or about 0.88 g / cm 3 ~Approx. 0.98g / cm 3 , or about 0.88 g / cm 3 ~Approx. 0.96g / cm 3 , or about 0.89 g / cm 3 ~Approx. 0.95g / cm 3 In the context of this disclosure, density refers to bulk density (as opposed to skeletal density).

[0094] In one embodiment, the high-density polyethylene membrane can have substantially no measurable airflow. In one embodiment, the air permeability of the high-density polyethylene membrane, when evaluated according to the ATEQ test described herein, is substantially zero (or undetectable), indicating substantially no airflow through the membrane. This helps prevent the ingress of contaminants, particularly water vapor, into the acoustic device, thereby protecting the acoustic device from water damage. Preventing water vapor from entering the acoustic device is important because water vapor can condense and cause the device to malfunction.

[0095] In some embodiments, the acoustic device can have an average delta transmission loss of less than about 3 dB, where the average delta transmission loss is calculated by subtracting the measured transmission loss before the pressure test from the measured transmission loss 24 hours after the pressure test, where the pressure test is a 30-minute test with an open-hole load of 1 bar and the sound frequency is 3 KHz. The acoustic device can have an average delta transmission loss of less than about 2.1 dB, or less than about 2.0 dB, or less than about 1.9 dB, or less than about 1.5 dB, or less than about 1.0 dB.

[0096] When a stiffener plate is used in an acoustic device, the acoustic device can have an average delta transmission loss of less than about 3 dB, where the average delta transmission loss is calculated by subtracting the measured transmission loss before the pressure test from the measured transmission loss 24 hours after the pressure test, where the pressure test is a 10 bar load for 15 minutes and the sound frequency is 3 KHz.

[0097] Figure 4 shows an example of a setup for pressure testing. Pressure testing can be performed by placing a sample membrane (300) between two rigid supports (302, 304). A selected level of either air or water pressure can then be applied to the membrane, causing it to deform into a dome shape (306). Pressure testing can also involve a stiffening plate positioned between the membrane (300) and the rigid support (302), but not in direct contact with the membrane when no pressure is applied. For example, the separation distance between the high-density polyethylene membrane and the stiffening plate can be approximately 50 μm. The arrow indicates the direction of pressure.

[0098] The average delta transmission loss (dB) is measured as set forth in the test methods described herein.

[0099] In one embodiment, the high-density polyethylene film has a thickness of about 0.7 μm to about 2.8 μm and an average mass per area of ​​about 0.6 g / m 2 ~Approx. 2.8g / m 2, and a geometric five-point modulus of elasticity of at least about 1500 MPa.

[0100] In another embodiment, the high density polyethylene film has a thickness of about 0.8 μm to about 2.4 μm and an average mass per area of ​​about 0.7 g / m 2 ~approx. 2.4g / m 2 , and a geometric five-point modulus of elasticity of at least 1500 MPa.

[0101] In another embodiment, the high density polyethylene film has a thickness of about 0.9 μm to about 1.6 μm and an average mass per area of ​​0.8 g / m 2 ~1.6g / m 2 , and a geometric five-point modulus of elasticity of at least about 1500 MPa.

[0102] [High-density polyethylene film manufacturing method]

[0103] The method for producing the high-density polyethylene film is not particularly limited, and any method known in the art can be used as long as the film has the required properties.

[0104] One method known in the art for producing porous polyethylene membranes is the wet or gel process. In this process, polyethylene is mixed with a hydrocarbon liquid and other additives. The mixture is heated onto a polymer melt and extruded into a sheet. The sheet can then be biaxially stretched before and / or after extraction of the hydrocarbon liquid to produce a microporous membrane. Details of various processes are known, such as those disclosed in U.S. Pat. Nos. 5,248,461, 4,873,034, 5,051,183, and 6,566,012, each of which is incorporated herein by reference in its entirety. Additional discussions include "Casting and Stretching of Filled and Unfilled UHMW Polyethylene Films" (Ir. FH Assinck, Centre for polymers and composites, Eindhoven University of Technology, Nov 1995) and "Porous Biaxially Oriented UHMWPE Films" (HM Fortuin, DSM Research BV, Department of Materials Technology-Fifth Int. Conf. of Environmental Ergonomics).

[0105] The high-density polyethylene membrane of the present disclosure can be produced by the "gel process" for producing high-density polyethylene film, which is described in numerous documents, such as U.S. Patent No. 4,948,544. For example, the high-density polyethylene membrane can be formed by dissolving a polyethylene polymer in a solvent to form a solution, forming the solution into a tape or sheet at a temperature above the solution temperature of the polyethylene polymer, cooling the tape or sheet to a temperature below the solution temperature to gel the tape or sheet, removing the solvent from the gelled tape or sheet, and biaxially stretching the gelled tape or sheet at a temperature above the melting temperature to form the high-density polyethylene membrane.

[0106] Alternatively, high density polyethylene films can be formed by the "paste process," which involves processing a polyethylene polymer into a tape or film, which is then subjected to processing conditions suitable for forming a dense film. Such processing conditions can include heat compression and / or biaxial stretching of the tape or film.

[0107] High-density polyethylene films can be formed by (i) forming a polyethylene tape from a polyethylene polymer, (ii) compressing the polyethylene tape below the melting temperature of the polyethylene polymer, and (iii) stretching the polyethylene tape in at least two directions above the melting temperature of the polyethylene polymer to form a high-density polyethylene film. The polyethylene polymer can have an average molecular weight of about 1,000,000 g / mol to about 10,000,000 g / mol, the compression temperature can be 120°C to 135°C, the compression pressure can be at least 1 MPa, and the stretching temperature can be 140°C to 170°C. The polyethylene tape can be formed by providing a paste containing a polyethylene polymer and a lubricant, forming the paste into a tape, and removing the lubricant to form a dry polyethylene tape. For example, polyethylene polymer particles can be first mixed with a suitable lubricant (such as an isoparaffinic hydrocarbon) according to the general method described in U.S. Pat. No. 9,926,416 B2. The lubricated polymer particles are then formed into a tape, sometimes called a sheet, which is then dried (to remove the lubricant) before being formed into a high-density polyethylene film using heat compression, biaxial stretching, or a combination thereof.

[0108] Those skilled in the art will understand that the exact conditions, process steps and amounts of each component will depend on the nature of the polyethylene polymer and the desired properties of the resulting high density polyethylene film.

[0109] High-density polyethylene films are formed from polyethylene polymers, including ultra-high molecular weight polyethylene. As noted above, in the context of this disclosure, ultra-high molecular weight polyethylene refers to polyethylene having an average molecular weight of about 1,000,000 g / mol to about 10,000,000 g / mol. In some embodiments, the ultra-high molecular weight polyethylene polymer has an average molecular weight of about 1,500,000 to about 10,000,000 g / mol, or about 2,000,000 g / mol to about 10,000,000 g / mol, or about 4,000,000 g / mol to about 8,000,000 g / mol.

[0110] The ultra-high molecular weight polyethylene polymer can be a homopolymer of ethylene or a copolymer of ethylene and at least one comonomer. Suitable copolymers include α-olefins or cyclic olefins having 3 to 20 carbon atoms, such as 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, cyclohexene, and dienes having up to 20 carbon atoms. The comonomer can be present in the polyethylene copolymer in an amount of 0.001 mol % to 10 mol %, or 0.01 mol % to 5 mol %, or 0.1 mol % to 1 mol %.

[0111] The polyethylene polymer can also include a blend of ultra-high molecular weight polyethylene and relatively low molecular weight polyethylene (eg, polyethylene having an average molecular weight less than about 1,000,000 g / mol).

[0112] The high density polyethylene film may also be treated, e.g., coated, etc. For the avoidance of doubt, the film thickness, average mass per area, geometric modulus and other properties referred to herein refer to the properties of the high density polyethylene film without any treatment or coating.

[0113] [Acoustic device manufacturing method]

[0114] The present disclosure provides a method for manufacturing an acoustic device as described herein, the method comprising the steps of providing a housing, an acoustic transducer, and a high-density polyethylene film, wherein the housing includes at least one opening communicating with the exterior of the acoustic device, disposing the acoustic transducer within the housing, and covering the at least one opening in the housing communicating with the exterior of the acoustic device with the polyethylene film.

[0115] The method may further include forming a high density polyethylene film by the "gel method" or "paste method" described above.

[0116] In some embodiments, the method can further include securing the high-density polyethylene membrane to the housing, for example, with an adhesive. In some embodiments, the method can further include hermetically sealing the high-density polyethylene membrane to the housing to provide a waterproof seal between the housing and the high-density polyethylene membrane. In this manner, the periphery of the high-density polyethylene membrane is sealed to the housing, covering the opening.

[0117] In some embodiments, the method may further include providing a stiffening plate and positioning the stiffening plate over the opening in the housing so that the stiffening plate provides support to the high-density polyethylene membrane when external pressure is applied to the acoustic device. The stiffening plate may be the same as described above. In one embodiment, the high-density polyethylene membrane is positioned between the opening in the housing and the stiffening plate.

[0118] [Use of high-density polyethylene films in acoustic devices]

[0119] The present disclosure provides for the use of the high-density polyethylene film described herein in an acoustic device. The high-density polyethylene film is used to cover an opening in a housing, preventing the ingress of water (including water vapor), dust (including fine dust), and other contaminants into the acoustic device and providing a barrier against these contaminants. This protects the acoustic transducer and, combined with the strength and acoustic properties of the high-density polyethylene film, ensures superior performance of the acoustic device.

[0120] In one embodiment, the high density polyethylene film can be used as a cover for a microphone or speaker. In another embodiment, the high density polyethylene film can be used as a cover for a microphone.

[0121] [Electronic devices including acoustic devices]

[0122] The electronic device may include the acoustic device of the present disclosure. The electronic device is not particularly limited and may include a smartwatch, a mobile phone, a digital camera, headphones, earphones, a voice recorder, etc. In one embodiment, the electronic device is a smartwatch.

[0123] [Test method]

[0124] These test methods are referenced above and in the Examples section below.

[0125] Mass per area: The sample is placed on a surface with a radius of 5.64 cm (area = 100 cm 2 Each sample was weighed using a Mettler Toledo ME104TE analytical balance, and the average of six samples was measured over a test area of ​​100 cm. 2 Divide by 100 and multiply by 100 to get the mass per area (g / m 2 The amount of oxidized carbon dioxide (CO2) was calculated.

[0126] Bulk Density: Using the thickness measured using a Mitutoyo Litematic thickness gauge (see description below), the bulk density of the sample was calculated using the following formula:

number

[0127] Therefore, bulk density includes the pore space within the sample in a volumetric measurement.

[0128] Bone Density: As specified in ASTM D3766, skeletal density is the ratio of the mass of a solid material to the sum of its volume and the volume of all closed (or blind) pores within the solid material. Therefore, the skeletal density of a solid is calculated by excluding all open pores but including the volume of internal (or blind) pores. When the thickness and mass of a polyethylene film are accurately known, the skeletal density cannot be lower than the true bulk density calculated by directly measuring the mass and volume. The skeletal density of polyethylene was assumed to be ρ(polymer) = 0.94 g / cc. The skeletal density of polyethylene can vary depending on the ratio of amorphous to crystalline regions in the polyethylene, which may be due to the polymer manufacturing process. The skeletal density of polyethylene films, including high-density polyethylene membranes, can be measured by gas pycnometry. Gas pycnometry instruments, such as the Micrometrics AccuPyc II 1340, can measure the skeletal volume of a material by helium gas displacement using Boyle's law volume-pressure relationship.

[0129] Air Flow: The ATEQ airflow test typically measures the laminar volumetric flow rate of air through membrane and film samples. This measurement is used to demonstrate that polyethylene films are non-porous with respect to measurable airflow. Each film sample is measured at a 2.99 cm cross-flow rate. 2The film was sandwiched between two plates to seal the area of ​​the film. An ATEQ® (ATEQ Corp., Livonia, Michigan) Premier D Compact Flow Tester was used to apply a differential air pressure of 1.2 kPa (12 mbar) across the film to determine whether the air flow rate was below the instrument's detection limit of 0.5 L / hr. The instrument was operated with a calibrated 30 L flow tube to ensure that no air flow was detected below the instrument's detection limit of 0.5 L / hr. If no air flow was detected, the film was determined to be non-porous.

[0130] Thickness: The contact thickness of the film was measured using a Mitutoyo Litematic VL-50S motorized height gauge (commercially available from Mitutoyo Corporation, Kawasaki, Japan). Optical measurements were performed by gently placing the sample film on a polished, flat granite block and lowering the contact probe to apply a force of 1 gram. The average of 12 measurements was used.

[0131] Transmission loss: Transmission loss and phase angle testing was performed by Impedance Tube Transfer Matrix Testing (ITTMT). The ITTMT is a modified version of ASTM-E2611-09, a standard test method for measuring transmission loss and phase of normally incident sound based on a four-microphone transfer matrix technique. All modifications to ASTM-E2611-09 are noted herein. The transfer matrix of the assembly was measured. The T12 element of the transfer matrix was used as the acoustic impedance value for all assemblies described in the examples.

[0132] Measurements were performed using an impedance tube over the frequency range of 500 Hz to 20,000 Hz. The tube had an inner diameter of 8 mm. The impedance tube was designed in accordance with ASTM E1050-12 and ASTM E2611-09. A JBL 2426H compression driver was attached to one end of the tube and driven by a Bruel and Kjaer Type 2735 amplifier connected to a 31-band ART 351 graphic equalizer. The measurement system included four Bruel and Kjaer Type 4138 microphones connected to a four-channel Bruel and Kjaer Type 3160-A-042 LAN-XI front end, including the generator output. Data were acquired and processed using Bruel and Kjaer PULSE Labshop and Type 7758 acoustic materials testing software, version 21.

[0133] The sample assembly used in the test had an inner diameter of 1.5 mm, which was smaller than the inner diameter of the impedance tube, so a pair of cone adapters was required to mount the sample assembly. The converging cone had an inlet diameter of 8 mm and an outlet diameter of 1.5 mm. The diverging cone had an inlet diameter of 1.5 mm and an outlet diameter of 8 mm.

[0134] When using a conical adapter, additional data processing was required to account for the converging shape of the cone. Theoretical formulas for calculating the transfer matrix of a conical adapter have been derived and can be found in the literature (Hua, X. and Herrin, D., "Practical Considerations When Using the Two-Load Method to Determine Transmission Loss of Mufflers and Silencers," SAE Int. J. Passeng. Cars-Mech. Syst. 6(2):1094-1101, 2013 and Mechel, FP (2008). Formulas of Acoustics. New York, NY: Springer).

[0135] Average 5-point modulus: To determine the average five-point modulus, polyethylene film samples were cut longitudinally and transversely using either an ASTM D638 Type V die (D638) (e.g., for 3.5-inch long dogbone samples) or an ASTM D412 Type F die (D412F) (e.g., for 5-inch long dogbone samples). Tensile load as a function of displacement was measured at a frequency of 50 Hz using an INSTRON® 5565 (Illinois Tool Works Inc., Norwood, Massachusetts) tensile tester with flat grips and a 100 N load cell. The grip separation distance for the ASTM D638V test was set to 3.18 cm, and a strain rate of 0.127 cm / s or 16.7% / s was used, using the ASTM-specified gauge length of 0.76 cm. The grip separation distance for ASTM D412F testing was set at 8.26 cm, and a strain rate of 0.847 cm / sec or 14.4% / sec was used, using the ASTM-specified gauge length of 5.89 cm. After placing the sample in the grips, the sample was pulled back 1.27 cm to obtain a baseline value, after which the tensile test was performed at the aforementioned strain rate. Three samples per condition were tested separately in each orthogonal direction (e.g., longitudinal and transverse). For each test, the maximum tensile modulus was measured using a maximum linear approximation, as described further below, and the respective average values ​​were reported.

[0136] The maximum linear fit was determined by importing the raw data obtained from the tensile tester into a data analysis program. The tensile modulus was calculated by a series of linear fits of stress vs. strain for each successive group of five data points collected by the tensile tester. The largest slope within each group of five data points was the five-point modulus for that sample. Three samples were tested for each orthogonal direction (e.g., longitudinal and transverse), and the average value was reported as the average five-point modulus. The larger of the two average five-point moduli determined for the two orthogonal directions was designated the modulus for the first direction. The smaller of the two average five-point moduli determined for the two orthogonal directions was designated the modulus for the second direction. Different data acquisition rates and different numbers of data points may be used to calculate the modulus, as long as the data region for fitting the slope is substantially linear and is not substantially affected by noise in both the stress and strain measurements.

[0137] Matrix Tensile Strength: To determine matrix tensile strength (MTS), polyethylene film samples were cut longitudinally and transversely using either an ASTM D638 Type V die (D638) or an ASTM D412 Type F die (D412F). Tensile load as a function of displacement was measured using an INSTRON® 5565 (Illinois Tool Works Inc., Norwood, MA) tensile tester with flat grips and a 100 N load cell. The grip separation distance for the ASTM D638V test was set at 3.18 cm, and a strain rate of 0.127 cm / s or 16.7% / s was used, using an ASTM-specified gauge length of 0.76 cm. The grip separation distance for the ASTM D412F test was set at 8.26 cm, and a strain rate of 0.847 cm / s or 14.4% / s was used, using an ASTM-specified gauge length of 5.89 cm. After placing the sample in the grips, the sample was pulled back 1.27 cm to obtain a baseline value, followed by tensile testing at the aforementioned strain rate. Three samples for each condition were tested separately in each orthogonal direction (e.g., longitudinal and transverse), and the respective average values ​​were reported.

[0138] Ultimate tensile strength was measured by an Instron load cell and is defined as the maximum load reached during each test divided by the cross-sectional area of ​​the center of the die-cut dogbone. Data was exported to a data analysis program. Three samples were tested in each orthogonal direction (e.g., longitudinal and transverse), and the average value for each was reported. The larger of the two average maximum tensile moduli measured in the two orthogonal directions was taken as the modulus for the first direction. The smaller of the two average maximum tensile moduli measured in the two orthogonal directions was taken as the modulus for the second direction.

[0139] Matrix tensile strength (MTS) is used to describe the tensile strength of the polymer that makes up a porous or non-porous article and is calculated using the following formula:

number

[0140] Transmission loss test before and after pressure test: The sample assemblies were subjected to the following pressure test procedure. The purpose of this test was to replicate the pressure experienced by the membrane assembly in a device immersed in water at a given depth for a given time. The permeation loss was measured before the pressure test and again 24 hours after the pressure test. The change in permeation loss due to the pressure test was calculated by subtracting the permeation loss before the test from the permeation loss after the test.

[0141] Biaxial pressure test: To apply a load pressure to the membrane sample, a flat membrane sheet was sandwiched between two aligned FR4 epoxy laminate sheets, each with a 1.6 mm diameter orifice, and bonded using a pressure-sensitive adhesive (tesa® 4983). The entire assembly was secured in a metal fixture containing a metal top plate with a 1.6 mm orifice aligned with the orifice in the FR4 sheet. The top plate was fastened with screws. The metal fixture was connected to a pressure vessel containing air. The pressure vessel was connected to a control box containing programmable functions allowing pressure ramping and pressure control of the air. The control box was programmed to ramp the incoming pressure at a ramp rate of 0.5 psi / s until a maximum gauge pressure of 14.5 psi (1 bar) was reached. This target pressure (e.g., 14.5 psi) represents an industry-standard submersion depth rating of 10 meters. When tested at 14.5 psi, the sample was held at the target pressure for 30 minutes. Alternatively, a gauge pressure of 145 psi (10 bar) was used, representing a submersion depth rating of 100 meters. When tested at 145 psi, samples were tested for 15 minutes and in combination with a stiffener plate.

[0142] FIG. 4 shows an example pressure test setup. A "pressure test" can be performed by placing a sample membrane 100 between two rigid supports 102, 104. A selected level of pressurized air can then be applied to the membrane. For example, a pressure test can involve applying 1 bar of air pressure to the membrane 100 for 30 minutes, or applying 10 bar of air pressure to the membrane 100 for 30 minutes in combination with the use of a stiffener plate. After the test period is over, pressure is no longer applied, allowing the membrane 100 to return to its original state.

[0143] Water vapor transmission coefficient: The determination of the water vapor permeability coefficient of the materials was carried out in accordance with ASTM method F-1249. The instrument used for the water vapor permeability testing of the materials was a MOCON Permatran-W Model 3 / 34 G (Ametek MOCON Inc., Minneapolis, MN). The permeation medium used was water vapor (55.3 mmHg) at 90% RH, the carrier gas was 100% nitrogen, dry, at atmospheric pressure, and the temperature at which the test was carried out was 40.0°C. The test area was approximately 5.0 cm. 2 or 50cm 2 The sample was cut out to a size of 1 / 2" x 1 / 2", masked, and fixed in the diffusion cell of the instrument. The water vapor transmission rate, or MVTR, was measured by the instrument in g / m 2 The water vapor transmission coefficient for each sample was calculated by multiplying the water vapor transmission rate by the thickness of the test sample. Results are reported in units of g-mm / m 2 Report in / day.

[0144] The sample assemblies described herein and the comparative sample assemblies were prepared as follows.

[0145] All example and comparative sample assemblies consisted of two adhesive-backed glass fiber sample carriers used to construct a sandwich structure containing a flat sheet membrane, hereafter referred to simply as the glass fiber sample carrier. The glass fiber sample carrier was fabricated by applying a double-sided pressure-sensitive adhesive (tesa® 4983) to one side of a glass fiber sheet (purchased from McMaster-Carr, product number 1331T37). The glass fiber / adhesive sheet was then laser cut into coupons. A central aperture approximately 1.6 mm in diameter was fabricated to align with the hole in the impedance tube and correspond to the active area of ​​the sample being measured.

[0146] All example and comparative sample assemblies fabricated with a stiffener plate for acoustic testing consisted of an adhesive-backed glass fiber sample carrier and a 300-micron-thick brass plate with an array of 150-200 micron diameter holes with an approximately 25% aperture ratio within an approximately 1.5 mm aperture, used to form a sandwich structure containing the flat membrane. The single-sided glass fiber sample carrier was prepared as described in the previous paragraph. Double-sided pressure-sensitive adhesive (Nitto Denko® 5605BN) with a pre-cut array of holes, including a 1.6 mm aperture aligned with the active area of ​​the sample to be measured, was applied to one side of the brass stiffener plate. The total thickness of the adhesive layer was approximately 50 microns, so that the membrane was approximately 50 microns away from the stiffener plate during acoustic testing. The approximately 1.6 mm diameter central aperture was aligned with the inner diameter of the impedance tube, corresponding to the active area of ​​the sample to be measured.

[0147] The adhesive membrane strip, placed in a four-sided rectangular cardboard frame, was partially cut away from two adjacent sides of the frame to release residual tension and placed on a smooth, level surface to ensure the membrane was flat and wrinkle-free. The adhesive release liner was peeled off from a pre-cut glass fiber sample carrier to expose the adhesive layer. With the adhesive layer exposed, the sample carrier was gently placed on top of the membrane, and excess membrane was trimmed from around the sample carrier. The sample carrier was then placed on the alignment jig with the membrane side facing up. The release liner was peeled off from a second glass fiber sample carrier and placed on the alignment jig with the membrane facing up and the adhesive side facing down. Light (i.e., by hand) pressure was applied to bond the bottom and top sample carriers together, forming an assembly with one of the following laminate structures: (1) glass fiber sample carrier / adhesive / membrane / adhesive / glass fiber sample carrier, or (2) glass fiber sample carrier / adhesive / membrane / adhesive / perforated brass stiffener plate. [Example]

[0148] [Example]

[0149] The present disclosure will be described in more detail with reference to examples, but the present disclosure is not limited to the following examples.

[0150] Example 1

[0151] Powder preparation:

[0152] 300 g of ultra-high molecular weight polyethylene (UHMWPE) powder with a molecular weight of approximately 7,000,000 g / mol (manufactured by Mitsui Chemicals, Inc., as described in WO2012053261) was placed in a 2-liter screw-cap jar. 180 mL of isoparaffinic hydrocarbon lubricant (Isopar™ V, Exxon Mobil Chemical Company, Spring, Texas) was added and mixed at 30 rpm for 15 minutes at room temperature. The mixture was preheated to 60°C before calendering.

[0153] Tape Calendering:

[0154] Calender rolls with a diameter of 20.3 cm were preheated to 121°C, and the gap between the rolls was set at 0.2 mm. Lubricated polymer was fed into the gap using a feeder, producing a continuous tape 15.2 cm wide at a line speed of 2.0 m / min. The tape was opaque, flexible, and approximately 0.21 mm thick.

[0155] Lubricant removal:

[0156] The tape was passed roll-to-roll through a large bath containing a low aromatic hydrocarbon solvent (Isopar™ G, Exxon Mobil Chemical Company, Spring, Texas) and dried at 50°C after which the Isopar V™ was replaced with Isopar™ G.

[0157] Heat compression:

[0158] After removing the lubricant, the dried tape was re-calendered between 30.5 cm diameter rolls preheated to 130° C., with a roll gap of 0.09 mm and a line speed of 0.3 mm / min. The resulting compressed tape was translucent and flexible.

[0159] Biaxial stretching:

[0160] Samples were cut from the tape and placed in a Karo IV biaxial stretching machine (commercially available from Bruckner Group GmbH, Siegsdorf, Germany) and simultaneously stretched according to the following procedure. 1. Preheat the sample to 145°C for 120 seconds. 2. Stretch at 145°C 6.0 times at 37.5% / sec in the calendar direction and 9.0 times at 37.5% / sec in the transverse direction (perpendicular to the calendar).

[0161] The properties of the resulting membrane are shown in Table 1. The resulting membrane was non-porous and had a pressure of 12 mbar, 2.99 cm 2 The air flow at is less than 0.5 L / hr. Matrix tensile strength and average 5-point modulus were calculated using the ASTM D638 Type V Dogbone method.

[0162] Example 2

[0163] The same hot-pressed paste-treated ultra-high molecular weight polyethylene (UHMWPE) tape described in Example 1 was treated as follows.

[0164] Biaxial stretching:

[0165] Samples were cut from the tape and placed in a Karo IV biaxial stretching machine (commercially available from Bruckner Group GmbH, Siegsdorf, Germany) and simultaneously stretched according to the following procedure. 1. Preheat the sample to 145°C for 120 seconds. 2. Stretch at 145°C 9.5 times in the calendar direction at 37.5% / sec and 9.5 times in the transverse direction (perpendicular to the calendar) at 37.5% / sec.

[0166] The properties of the resulting membrane are shown in Table 1. The resulting membrane was non-porous and had a pressure of 12 mbar, 2.99 cm 2 The air flow at is less than 0.5 L / hr. Matrix tensile strength and average 5-point modulus were calculated using ASTM D638 Type V Dogbone.

[0167] Example 3

[0168] In this example, the mass per area is 2.44 g / m 2 , 12 mbar, 2.99 cm 2 A gel-processed ultra-high molecular weight polyethylene (UHMWPE) membrane with an air flow of 4.9 L / h at 1000 W / s, a thickness of 9.6 μm, an ultimate tensile strength of 76 MPa in a first direction, and an ultimate tensile strength of 65 MPa in a second direction (orthogonal to the first direction) was used as the precursor. According to the supplier, the starting resin used to fabricate the membrane had a molecular weight of 4,300,000 g / mol.

[0169] The membrane was stretched in the longitudinal / machine direction between roll banks at a gap distance of 19 cm and a running speed of 3.0 m / min on a heated plate set at 130° C. The speed ratio between the second roll bank and the first roll bank, i.e., the stretch ratio, was 2:1.

[0170] The longitudinally stretched membrane was then stretched in the transverse direction at a ratio of 3.2:1 at a temperature of about 145° C., a strain rate of 3.7% / sec, and a dwell time of 3.5 minutes.

[0171] The properties of the resulting membrane are shown in Table 1. The resulting membrane was non-porous and had a pressure of 12 mbar, 2.99 cm 2 The air flow at is less than 0.5 L / hr. Matrix tensile strength and average 5-point modulus were calculated using ASTM D412F type dogbone.

[0172] Example 4

[0173] In this example, the mass per area is 3.92 g / m 2 , 12 mbar, 2.99 cm 2A gel-processed ultra-high molecular weight polyethylene (UHMWPE) membrane with an air flow of 3.3 L / hr at 1000 W / m², a thickness of 10.8 μm, an ultimate tensile strength of 107 MPa in a first direction, and an ultimate tensile strength of 85 MPa in a second direction (orthogonal to the first direction) was used as the precursor. According to the supplier, the starting resin used to fabricate the membrane had a molecular weight of 4,300,000 g / mol.

[0174] The membrane was stretched in the longitudinal / machine direction between roll banks at a gap distance of 36 cm and a running speed of 4.6 m / min on a heated plate set at a temperature of 130° C. The speed ratio between the second roll bank and the first roll bank, i.e. the stretch ratio, was 2:1.

[0175] The longitudinally stretched membrane was then stretched in the transverse direction at a ratio of 3.0:1 at approximately 145°C, with a stretching speed of 2 m / min, a strain rate of 3.5% / sec, and a dwell time of 2.5 min, followed by a restrained heat treatment at 150°C for 1.0 min.

[0176] The properties of the resulting membrane are shown in Table 1. The resulting membrane was non-porous and had a pressure of 12 mbar, 2.99 cm 2 The air flow at the temperature was less than 0.5 L / hr. Matrix tensile strength and average five-point modulus were calculated using an ASTM D412F dogbone testing machine.

[0177] Example 5

[0178] A gel-treated ultra-high molecular weight polyethylene (UHMWPE) membrane identical to that described in Example 4 was treated as follows.

[0179] The membrane was stretched in the longitudinal / machine direction between roll banks at a gap distance of 36 cm and a running speed of 4.6 m / min on a heated plate set at a temperature of 130° C. The speed ratio between the second roll bank and the first roll bank, i.e. the stretch ratio, was 2:1.

[0180] The longitudinally stretched membrane was then stretched transversely at a ratio of 3.35:1 at a temperature of approximately 145°C, a running speed of 2 m / min, a strain rate of 3.9% / sec, and a residence time of 2.5 min, followed by a restrained heat treatment at 150°C with a residence time of 1.0 min.

[0181] The properties of the resulting membrane are shown in Table 1. The resulting membrane was non-porous and had a pressure of 12 mbar, 2.99 cm 2 The air flow at is less than 0.5 L / hr. Matrix tensile strength and average 5-point modulus were calculated using ASTM D412F type dogbone.

[0182] Example 6

[0183] Using a Karo IV biaxial pantograph apparatus (commercially available from Bruckner Group GmbH, Siegsdorf, Germany), a gel-processed initial membrane identical to that used in Example 3 was heated to 150°C for 60 seconds while restrained in both the longitudinal and transverse directions. The sample was then stretched simultaneously in both directions at a constant rate of 0.7% / sec, resulting in a stretching ratio of 1.7 x 1.7.

[0184] The properties of the resulting membrane are shown in Table 1. The resulting membrane was non-porous and had a pressure of 12 mbar, 2.99 cm 2 The airflow rate at this temperature is less than 0.5 L / hr. Matrix tensile strength and average 5-point modulus were calculated using ASTM D638 V-type dogbone.

[0185] Example 7

[0186] A gel-treated ultra-high molecular weight polyethylene (UHMWPE) membrane identical to that described in Example 3 was treated as follows.

[0187] The membrane was stretched in the longitudinal / machine direction between a series of rolls at a gap distance of 19 cm and a running speed of 3.0 m / min on a heated plate set at 130° C. The speed ratio between the second roll group and the first roll group, i.e., the stretch ratio, was 2.5:1.

[0188] The longitudinally stretched membrane was then stretched in the transverse direction at a temperature of about 147° C. using a stretch ratio of 3.2:1, a strain rate of 3.7% / sec, and a residence time of 3.5 minutes.

[0189] The properties of the resulting membrane are shown in Table 1. The resulting membrane was non-porous and had a pressure of 12 mbar, 2.99 cm 2 The air flow is less than 0.5 L / hr. Matrix tensile strength and average 5-point modulus were calculated using ASTM D412F type dogbone.

[0190] Comparative Example 1

[0191] Using a Karo IV biaxial pantograph apparatus, a 13 micron LDPE film (available from Ace Hardware, part number 11165, manufacturer part number 626206) was heated to 85°C for 60 seconds while restrained in both the longitudinal and transverse directions with the diffuser in the off position. The sample was then stretched simultaneously in both directions at a constant rate of 0.7% / sec by a 1.4 x 1.4 ratio.

[0192] The properties of the resulting membrane are shown in Table 1. The resulting membrane was non-porous and had a pressure of 12 mbar, 2.99 cm 2 with an air flow of less than 0.5 L / hr. Matrix tensile strength and average 5-point modulus were calculated using ASTM D412F type dogbone.

[0193] Comparative Example 2

[0194] Using a Karo IV biaxial pantograph apparatus, the same 13 micron commercial LDPE micron film used in Comparative Example 1 was heated to 115°C for 60 seconds while restrained in both the longitudinal and transverse directions with the diffuser in the off position. The sample was then stretched simultaneously in both directions at a constant rate of 0.7% / sec by a ratio of 1.8 x 1.8.

[0195] The resulting membrane was bifurcated into thin and thick striations. After removing the samples, the thickness and sound transmission loss were measured using samples selected only from the thick region of the membrane.

[0196] The properties of the thick region of the membrane are shown in Table 1. The resulting membrane was non-porous and had a pore size of 12 mbar, 2.99 cm 2 The air flow at is less than 0.5 L / hr. Matrix tensile strength and average 5-point modulus were calculated using ASTM D412F type dogbone.

[0197] Comparative Example 3

[0198] A PTFE high density film was produced according to the specification of U.S. Patent No. 7,521,010 (B2). The properties of the resulting membrane are shown in Table 1. The resulting membrane was non-porous and had a viscosity of 12 mbar, 2.99 cm 2 The air flow at is less than 0.5 L / hr. Matrix tensile strength and average 5-point modulus were calculated using ASTM D412F type dogbone. [Table 1]

[0199] Examples 1-7 represent membranes according to the present disclosure. Comparative Examples 1-3 represent membranes not according to the present disclosure.

[0200] Examples 1 to 7 each have a higher geometric mean five-point elastic modulus than Comparative Examples 1 to 3, and therefore have excellent strength properties despite their smaller film thickness and average mass per area.

[0201] Transmission Loss Test:

[0202] Sample assemblies containing the membranes of Examples 1-7 and comparative sample assemblies containing the membranes of Comparative Examples 1-3 were constructed according to the method described above. The permeation loss and delta permeation loss of the membranes of Examples 1-7 and Comparative Examples 1-3 were tested according to the test method described above. Table 2 shows the 3 kHz delta permeation loss (dB) for a 30-minute pressure test at 1 bar with an open-hole load (as shown in Figure 4) without a reinforcing plate. Table 2 also shows the 3 kHz delta permeation loss (dB) for a 15-minute pressure test at 10 bar with a reinforcing plate positioned between the membrane (300) and the rigid support (102) but not in contact with the membrane when no pressure is applied. The separation gap between the reinforcing plate and the high-density polyethylene membrane is approximately 50 μm. [Table 2]

[0203] The membranes of Examples 1 to 7 had significantly lower initial and delta transmission losses in both 1 bar and 10 bar tests (with stiffener) compared to the membranes of Comparative Examples 1 and 3, and the membrane of Comparative Example 2 failed during the test at 10 bar. Therefore, the membranes of Examples 1 to 7 are more suitable for acoustic devices.

[0204] Thus, from the examples it is clear that the high-density polyethylene film prevents the intrusion of water (including water vapor), dust (including fine dust) and other contaminants into the acoustic device, the high-density polyethylene film is strong enough to withstand external pressure, and the high-density polyethylene film does not result in significant sound transmission loss.

[0205] Example 8

[0206] In this example, the mass per area is 3.65 g / m 2 , 12 mbar, 2.99 cm 2A gel-processed ultra-high molecular weight polyethylene (UHMWPE) membrane was used as the precursor, with a thickness of 11.8 μm, a tensile strength of 78.4 MPa in a first direction, and a tensile strength of 63.3 MPa in a second direction (perpendicular to the first direction). According to the supplier, the starting resin used to fabricate the membrane had a molecular weight of 4,300,000 g / mol.

[0207] The membrane was stretched in the transverse direction at a ratio of 1.9:1 at a temperature of about 135° C., with a running speed of 2 m / min, a strain rate of 1.6% / sec, and a residence time of 2.5 minutes. This was followed by an additional transverse stretch at a ratio of 1.2:1 at a temperature of about 150° C., with a running speed of 2 m / min, a strain rate of 0.8% / sec, and a residence time of 0.5 minutes. This was followed by a restrained heat treatment at 150° C. with a residence time of 0.5 minutes.

[0208] The properties of the resulting membrane are detailed in Table 3. The resulting membrane was non-porous and had a pore size of 12 mbar and 2.99 cm 2 with an air flow of less than 0.5 L / hr. Matrix tensile strength and average 5-point modulus were calculated using ASTM D412F type dogbone. [Table 3]

[0209] A physical vapor deposition layer of tantalum was formed on an ultra-high molecular weight polyethylene film using a Denton Vacuum Explore™-14 sputtering system containing a Kurt J. Lesker 99.95% pure, 3.00-inch diameter x 0.250-inch thick tantalum target, krypton (99.9%) (Airgas) process gas, and an argon / oxygen mixture (containing 2% O) (Airgas) vent gas, using the following process. The UHMWPE film sample with a Kapton backer was secured to the sample stage of the sputtering system with Kapton tape. Cathode 1 was used during deposition, and the target was positioned in a confocal setup so that the center of the target was approximately 9 cm above the sample stage. To achieve a thickness of the Ta coating deposited on the film in the nanometer range, the following conditions were used: chamber pressure 60 mTorr, Kr process gas flow rate 40 standard cubic cm / min, power (DC) 300 W, and deposition times of 1, 2, and 5 seconds.

[0210] Figure 5 (Figure 5) shows a scanning electron microscope (SEM) photograph of a cross section of UHMWPE coated with tantalum using a 5-second deposition time. The SEM was prepared by directly mounting the surface sample on double-sided carbon tape (Ted Pella, California) attached to an SEM mount. The cross section was prepared using a Gatan® Illion2 broad beam ion mill (Gatan, California). The sample was coated with a thin layer of platinum using a Cressington® 208HR sputter coater (Cressington, UK), and SEM analysis was performed using a Hitachi® SU8230 field emission electron microscope (FESEM) (Hitachi, Japan).

[0211] The average thickness of the deposited tantalum layer was determined to be 18 nm as the average of 14 measurements. The density of tantalum was 16.65 g / cm 3 , the mass per area of ​​UHMWPE is 1.4 g / m 2 Assuming this, the mass per area of ​​tantalum metal is 0.3 g / m 2The presence of the tantalum layer increases the mass density by 21% compared to UHMWPE without the tantalum layer.

[0212] Figure 6 (Figure 6) shows the sound transmission loss of UHMWPE without a tantalum layer (deposition time 0 seconds) and samples with a tantalum layer deposited for 1 second, 2 seconds, and 5 seconds (no reinforcing plate at the initial time).

[0213] Error bands were constructed using the minimum and maximum measurements for each of the three replicate test coupons and condition. The range of each data curve for the four individual deposition conditions indicates that the initial sound transmission loss is substantially unaffected by the presence of tantalum layers up to approximately 20 nanometers thick.

[0214] All ranges described herein are exemplary in nature and include all values ​​therebetween. As used herein, the terms "substantially," "approximately," and "about" are used interchangeably and refer to measurements, including the stated measurement and any measurement reasonably close to the stated measurement. A measurement reasonably close to the stated measurement deviates from the stated measurement by a reasonably small amount, to the extent that it would be understood and easily ascertained by one of ordinary skill in the relevant art. Such deviations may result from measurement error, differences in the calibration of measuring and / or manufacturing equipment, human error in reading and / or setting measurements, fine-tuning made to optimize performance and / or structural parameters given variations in measurements associated with other components, specific implementation scenarios, imprecise adjustment and / or manipulation of objects by humans or machines. If it is determined that such a reasonably small deviation would not be easily ascertainable by one of ordinary skill in the relevant art, the terms "about" and "approximately" may be understood to mean plus or minus 10% of the stated value.

[0215] Throughout this specification and claims, terms have the meanings expressly defined herein unless the context clearly dictates otherwise.

[0216] As used herein, phrases such as "in one embodiment," "in an embodiment," and "in some embodiments" do not necessarily refer to the same embodiment, but may. Additionally, as used herein, the phrases "in another embodiment" and "in some other embodiments" do not necessarily refer to different embodiments, but may. All embodiments of the present disclosure are intended to be combinable.

[0217] The terms "comprises" and "comprising" mean including, but not limited to, that additional features may be present. These terms can also mean "consistent of."

[0218] All references and test methods cited herein are incorporated by reference in their entirety.

Claims

1. An acoustic device (100), a housing (110) including at least one opening (112) communicating with the exterior of the acoustic device; an acoustic transducer (120); and a high density polyethylene film (130) covering said at least one opening communicating with the exterior of said acoustic device; Including, The acoustic transducer is disposed in a housing (114); the high-density polyethylene film has a first direction and a second direction, the second direction being perpendicular to the first direction; the high-density polyethylene film has a thickness of about 0.5 μm to about 3.0 μm, the first direction and the second direction are each perpendicular to the thickness direction; The high density polyethylene film has an average mass per area of ​​about 0.4 g / m ２ ~Approx. 3g / m ２ and the high-density polyethylene film has a geometric mean five-point modulus of at least about 1500 MPa; and An acoustic device (100), wherein the high density polyethylene film is formed from a polyethylene polymer, including ultra-high molecular weight polyethylene.

2. The acoustic device of claim 1 , wherein said high-density polyethylene film has an average five-point modulus in said first direction of at least about 1500 MPa.

3. 3. The acoustic device of claim 1 or claim 2, wherein the high-density polyethylene film has an average five-point modulus in the second direction of at least about 1000 MPa.

4. The acoustic device of any one of claims 1 to 3, wherein the high-density polyethylene film has an average matrix tensile strength (MTS) in the first direction of at least about 200 MPa.

5. The acoustic device of any one of claims 1 to 4, wherein the high-density polyethylene film has an average matrix tensile strength (MTS) in the second direction of at least about 150 MPa.

6. The acoustic device of any one of claims 1 to 5, wherein the high-density polyethylene film has a geometric mean matrix tensile strength (MTS) of at least about 175 MPa.

7. The high density polyethylene film has a water vapor permeability coefficient of about 0.0001 g-mm / m ２ / day ~ approx. 0.3g-mm / m ２ The acoustic device according to any one of claims 1 to 6, wherein the acoustic device has a power consumption of 100 W / day.

8. The high density polyethylene film has a density of at least about 0.88 g / cm ３ The acoustic device according to any one of claims 1 to 7,

9. An acoustic device according to any one of claims 1 to 8, wherein the high density polyethylene film is substantially free of measurable airflow.

10. 10. The acoustic device of any one of claims 1-9, wherein the acoustic device has an average delta transmission loss (dB) of less than about 3 dB, wherein the average delta transmission loss is calculated by subtracting the measured transmission loss before a pressure test from the measured transmission loss 24 hours after a pressure test, wherein the pressure test is an open hole load of 1 bar and the acoustic frequency is 3 KHz.

11. An acoustic device according to any one of claims 1 to 10, wherein the high density polyethylene film has a thickness of from about 0.7 μm to about 2.8 μm, or optionally from about 0.8 μm to about 2.4 μm.

12. The high density polyethylene film has an average mass per area of ​​about 0.6 g / m ２ ~Approx. 2.8g / m ２ , or in some cases about 0.7 g / m ２ ~ about 2.4 g / m ２ The acoustic device according to any one of claims 1 to 11,

13. An acoustic device according to any one of claims 1 to 12, further comprising a stiffening plate (210) for supporting said polyethylene membrane.

14. 14. The acoustic device according to claim 13, wherein the reinforcing plate is selected from the group consisting of a perforated metal plate, a woven fabric, a nonwoven fabric, a mesh, a net, a sponge, a foam, and a porous metal or resin body.

15. 15. The acoustic device of claim 13 or 14, wherein the acoustic device has an average delta transmission loss (dB) of less than about 3 dB, wherein the delta transmission loss is calculated by subtracting the measured transmission loss before a pressure test from the measured transmission loss 24 hours after a pressure test, wherein the pressure test is at a load of 10 bar and the acoustic frequency is 3 KHz.

16. The acoustic device of any one of claims 1 to 15, further comprising a coating layer on the surface of the high-density polyethylene film.

17. The acoustic device of claim 16 , wherein the high-density polyethylene film is disposed between the coating layer and the acoustic transducer.

18. 18. An acoustic device according to claim 16 or claim 17, wherein the coating layer comprises an anti-static component.

19. The acoustic device of any one of claims 1 to 18, wherein the high density polyethylene film further comprises an antistatic component within the high density polyethylene film.

20. 20. An acoustic device according to claim 18 or 19, wherein the antistatic component is selected from one or more of the group consisting of metals, carbon and electronically conductive polymers.

21. An acoustic device according to any preceding claim, wherein the acoustic transducer is disposed within the housing such that the opening directs sound to the acoustic transducer.

22. 22. The acoustic device of any one of claims 1 to 21, wherein the ultra-high molecular weight polyethylene has an average molecular weight of from about 1,000,000 g / mol to about 10,000,000 g / mol, optionally from about 2,000,000 g / mol to about 10,000,000 g / mol.

23. The high density polyethylene film can be prepared by the following method: dissolving a polyethylene polymer in a solvent to form a solution; casting the solution into a tape at a temperature above the solution temperature of the polyethylene polymer; cooling the tape to a temperature below the solution temperature to gel the tape; removing the solvent from the gelled tape; and biaxially stretching the gelled tape at a temperature above the melting temperature to form a high density polyethylene film; 23. The acoustic device of claim 1, manufactured by

24. The high density polyethylene film can be prepared by the following method: providing a paste comprising a polyethylene polymer and a lubricant; forming the paste into a tape; removing the lubricant from the tape to form a dry polyethylene tape; compressing the dry polyethylene tape at a temperature below the melting temperature of the polyethylene polymer; and stretching the polyethylene tape in at least two directions at a temperature above the melting temperature of the polyethylene polymer to form a high density polyethylene film; 23. The acoustic device of claim 1, manufactured by

25. The acoustic device according to any one of claims 1 to 24, wherein the acoustic device is a microphone or a speaker.

26. An electronic device comprising an acoustic device according to any one of claims 1 to 25, optionally being a smartwatch.

27. A method for manufacturing an acoustic device (100) according to any one of claims 1 to 25, comprising the steps of: (i) providing a housing (110), an acoustic transducer (120), and a high-density polyethylene film (130), wherein the housing includes at least one opening (112) communicating with the exterior of the acoustic device; (ii) disposing the acoustic transducer within a housing (114); and (iii) covering the at least one opening in the housing that communicates with the exterior of the acoustic device with the high-density polyethylene film; A method comprising the steps of:

28. The method of claim 27, further comprising securing the high density polyethylene film to the housing with an adhesive (140).

29. 29. The method of claim 27 or 28, further comprising hermetically sealing the high density polyethylene membrane to the housing.

30. The method of any one of claims 27 to 29, further comprising providing a stiffening plate (210) and positioning said stiffening plate over at least one opening in said housing to provide support for said high density polyethylene membrane.

31. Use of a high density polyethylene film (130) in an acoustic device (100), comprising: the high-density polyethylene film has a first direction and a second direction, the second direction being perpendicular to the first direction; the high-density polyethylene film has a thickness of about 0.5 μm to about 3.0 μm, the first direction and the second direction are each perpendicular to the thickness direction; The high density polyethylene film has an average mass per area of ​​about 0.4 g / m ２ ~Approx. 3g / m ２ and the high-density polyethylene film has a geometric mean five-point modulus of at least about 1500 MPa; and 1. Use of a high density polyethylene membrane (130), wherein said high density polyethylene membrane is formed from a polyethylene polymer including ultra-high molecular weight polyethylene.

32. 32. The use of claim 31, wherein the acoustic device comprises a housing (110) including at least one opening (112) communicating with the outside of the acoustic device and an acoustic transducer (120), the acoustic transducer being disposed within a housing (114), and the high-density polyethylene film being used to cover the at least one opening of the housing, thereby preventing the ingress of water, dust and / or other contaminants.

Images