CN111935605B - Composite diaphragm of sound production device, preparation method of composite diaphragm and sound production device - Google Patents

Composite diaphragm of sound production device, preparation method of composite diaphragm and sound production device Download PDF

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CN111935605B
CN111935605B CN202011010813.0A CN202011010813A CN111935605B CN 111935605 B CN111935605 B CN 111935605B CN 202011010813 A CN202011010813 A CN 202011010813A CN 111935605 B CN111935605 B CN 111935605B
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diaphragm
composite
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rubber layer
composite diaphragm
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CN111935605A (en
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周厚强
闫付臻
李春
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Goertek Inc
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Goertek Inc
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R7/00—Diaphragms for electromechanical transducers; Cones
    • H04R7/02—Diaphragms for electromechanical transducers; Cones characterised by the construction
    • H04R7/04—Plane diaphragms
    • H04R7/06—Plane diaphragms comprising a plurality of sections or layers
    • H04R7/10—Plane diaphragms comprising a plurality of sections or layers comprising superposed layers in contact
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B25/00—Layered products comprising a layer of natural or synthetic rubber
    • B32B25/04—Layered products comprising a layer of natural or synthetic rubber comprising rubber as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B25/08—Layered products comprising a layer of natural or synthetic rubber comprising rubber as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B25/00—Layered products comprising a layer of natural or synthetic rubber
    • B32B25/16—Layered products comprising a layer of natural or synthetic rubber comprising polydienes homopolymers or poly-halodienes homopolymers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/28—Layered products comprising a layer of synthetic resin comprising synthetic resins not wholly covered by any one of the sub-groups B32B27/30 - B32B27/42
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/34—Layered products comprising a layer of synthetic resin comprising polyamides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/36—Layered products comprising a layer of synthetic resin comprising polyesters
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/36—Layered products comprising a layer of synthetic resin comprising polyesters
    • B32B27/365—Layered products comprising a layer of synthetic resin comprising polyesters comprising polycarbonates
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R31/00—Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor
    • H04R31/003—Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor for diaphragms or their outer suspension
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R2231/00—Details of apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor covered by H04R31/00, not provided for in its subgroups
    • H04R2231/001—Moulding aspects of diaphragm or surround
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R2307/00—Details of diaphragms or cones for electromechanical transducers, their suspension or their manufacture covered by H04R7/00 or H04R31/003, not provided for in any of its subgroups
    • H04R2307/025—Diaphragms comprising polymeric materials

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Manufacturing & Machinery (AREA)
  • Multimedia (AREA)
  • Laminated Bodies (AREA)

Abstract

The invention discloses a composite diaphragm of a sound generating device, a preparation method thereof and the sound generating device, wherein the composite diaphragm comprises the following steps: compounding the nitrile rubber layer and the engineering plastic layer together to form a composite film; and carrying out molding treatment on the composite membrane to form a composite diaphragm, wherein in the molding treatment, the engineering plastic layer is attached to a molding die. According to the composite diaphragm, the nitrile rubber layer and the engineering plastic layer are compounded to form a composite structure, and the inventor finds that the composite structure generates function complementation and synergy, obtains unexpected technical effects and effectively improves the sensitivity; and the composite diaphragm is in the forming treatment, the engineering plastic layer is attached to the forming die, so that the problem of difficult demoulding of the single-layer diaphragm of the nitrile rubber layer in the forming process is solved, the warping deformation of the diaphragm product is reduced, and the appearance size of the diaphragm meets the design and use requirements.

Description

Composite diaphragm of sound production device, preparation method of composite diaphragm and sound production device
Technical Field
The invention relates to the field of acoustic products, in particular to a composite vibrating diaphragm of a sound generating device, a preparation method of the composite vibrating diaphragm and the sound generating device.
Background
Sound generators are important acoustic devices for consumer electronics that convert electrical signals into sound. In recent years, consumer electronics have been developed rapidly, and the performance requirements of consumers on the electronics are higher and higher, and the application fields and environments of the electronics are more and more complicated. Under such application requirements, the performance of the sound emitting device also needs to be improved. The existing sound generating device usually adopts a vibrating diaphragm as a vibration sound generating element, and the vibrating diaphragm plays a crucial role in the sound reproduction performance of the sound generating device and determines the conversion quality from electric energy to sound energy of the sound generating device.
The vibrating diaphragm of the existing sound generating device mostly adopts a nitrile rubber single-layer vibrating diaphragm which has higher damping property and rebound resilience, and the rubber layer adopts a chemical crosslinking structure, so that the temperature resistance and the waterproof performance are excellent, and the nitrile rubber single-layer vibrating diaphragm is widely applied to sound generating device products.
However, in the process of implementing the embodiments of the present application, the inventors of the present application found that the above-mentioned technology has at least the following technical problems: (1) the nitrile rubber single-layer vibrating diaphragm product is easy to warp and deform, so that the size of the vibrating diaphragm is changed, the flatness is poor, and the yield of the product is reduced; (2) the sensitivity of the single-layer ethylene propylene rubber diaphragm is limited.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention mainly aims to provide the composite diaphragm of the sound generating device, the preparation method of the composite diaphragm and the sound generating device, so that the warping deformation of a nitrile rubber single-layer diaphragm product is reduced, the appearance size of the diaphragm is ensured to meet the design and use requirements, and meanwhile, the sensitivity of the diaphragm is effectively improved.
The technical problem to be solved by the invention is realized by the following technical scheme:
the invention provides a preparation method of a composite diaphragm of a sound generating device, which comprises the following steps:
compounding the nitrile rubber layer and the engineering plastic layer together to form a composite film;
and carrying out molding treatment on the composite membrane to form a composite diaphragm, wherein in the molding treatment, the engineering plastic layer is attached to a molding die.
Optionally, the butadiene-acrylonitrile rubber layer is made of butadiene-acrylonitrile copolymer, wherein the mass of acrylonitrile is 20-40% of the total mass of the butadiene-acrylonitrile copolymer.
Optionally, the preparation method of the nitrile rubber layer comprises the following steps: preparing a membrane body through a coating process, and drying the membrane body at low temperature to form an uncrosslinked rubber layer or a semi-crosslinked rubber layer; or the membrane body is made by a calendaring process, and the membrane body is an uncrosslinked rubber layer.
Optionally, the molding process is air pressure molding or compression molding.
Optionally, the butadiene-acrylonitrile copolymer is further mixed with an inorganic filler reinforcing agent, and the inorganic filler reinforcing agent adopts at least one of silicon oxide, silicate, carbonate and amorphous carbon.
Optionally, the mass of the inorganic filler reinforcing agent is 0-50% of the total amount of the butadiene-acrylonitrile copolymer.
Optionally, the butadiene-acrylonitrile copolymer is further mixed with a cross-linking agent, and the cross-linking agent comprises at least one of a sulfur-type cross-linking agent, a peroxide-based cross-linking agent, an alkyl phenol resin cross-linking agent and thiuram polysulfide.
Optionally, the mass of the cross-linking agent is 0.5-10% of the total mass of the butadiene-acrylonitrile copolymer.
Optionally, the thickness of the nitrile rubber layer is 5-100 μm.
Optionally, the nitrile rubber layer has a hardness of 25-75A.
Optionally, the engineering plastic layer is made of at least one of polyamide, polycarbonate, polyformaldehyde, polyethylene terephthalate, polybutylene terephthalate, polyarylsulfone, polyethersulfone, polyimide, polyphenylene sulfide, polyarylate, polyphenyl ester, polyaryletherketone and polyetheretherketone.
Optionally, the engineering plastic layer has a thickness of 1-30 μm.
Optionally, the composite diaphragm includes two engineering plastic layers and a nitrile rubber layer, and the two engineering plastic layers are respectively disposed on two surfaces of the nitrile rubber layer.
Optionally, the composite diaphragm further includes a thermoplastic elastomer layer, where the thermoplastic elastomer layer is one of the surface layers of the diaphragm, and the thermoplastic elastomer layer is connected to the nitrile rubber layer.
Optionally, the material of the thermoplastic elastomer layer is at least one selected from polyester thermoplastic elastomers, polyurethane thermoplastic elastomers, polyamide thermoplastic elastomers, polystyrene thermoplastic elastomers, and polyolefin thermoplastic elastomers.
According to another aspect of the invention, a composite diaphragm of a sound generating device is provided, which is prepared by the preparation method.
According to another aspect of the present invention, a sound generating apparatus is provided, which includes the composite diaphragm.
The invention has the following beneficial effects:
according to the composite diaphragm, the nitrile rubber layer and the engineering plastic layer are compounded to form a composite structure, and the inventor finds that the composite structure generates function complementation and synergy, obtains unexpected technical effects and effectively improves the sensitivity; and the composite diaphragm is in the forming treatment, the engineering plastic layer is attached to the forming die, so that the problem of difficult demoulding of the single-layer diaphragm of the nitrile rubber layer in the forming process is solved, the warping deformation of the diaphragm product is reduced, and the appearance size of the diaphragm meets the design and use requirements.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a composite diaphragm in embodiment 1 of the present invention;
fig. 2 is a schematic structural diagram of a composite diaphragm in embodiment 2 of the present invention;
fig. 3 is a schematic structural diagram of a composite diaphragm in embodiment 3 of the present invention;
fig. 4 is a graph showing FR curves of diaphragms in example 2 of the present invention and comparative example 1.
Detailed Description
The raw materials and equipment used in the invention are common raw materials and equipment in the field if not specified; the methods used in the present invention are conventional in the art unless otherwise specified.
Unless otherwise defined, terms used in the present specification have the same meaning as those generally understood by those skilled in the art, but in case of conflict, the definitions in the present specification shall control.
The use of "including," "comprising," "containing," "having," or other variations thereof herein, is meant to encompass the non-exclusive inclusion, as such terms are not to be construed. The term "comprising" means that other steps and ingredients can be added that do not affect the end result. The term "comprising" also includes the terms "consisting of …" and "consisting essentially of …". The compositions and methods/processes of the present invention comprise, consist of, and consist essentially of the essential elements and limitations described herein, as well as any of the additional or optional ingredients, components, steps, or limitations described herein.
All numbers or expressions referring to quantities of ingredients, process conditions, etc. used in the specification and claims are to be understood as modified in all instances by the term "about". All ranges directed to the same component or property are inclusive of the endpoints, and independently combinable. Because these ranges are continuous, they include every value between the minimum and maximum values. It should also be understood that any numerical range recited herein is intended to include all sub-ranges within that range.
As described in the background art, most of the diaphragms of the sound generating devices in the prior art adopt nitrile rubber single-layer diaphragms, and such nitrile rubber single-layer diaphragms are prone to warping and deformation, so that the diaphragm size changes, the flatness deteriorates, the product yield is reduced, and the sensitivity of the diaphragms is reduced, but this problem is not noticed by people, the reason for this problem is not clear, and the inventor finds out that the reason is: when the shaping formed the vibrating diaphragm, nitrile rubber vulcanizes under high temperature high pressure, closely laminates with forming die and causes the vibrating diaphragm drawing of patterns difficulty, and at the drawing of patterns in-process, the vibrating diaphragm is dragged the deformation easily, makes the vibrating diaphragm size change, and the roughness variation leads to the product yield to reduce. According to the invention, the nitrile rubber layer and the engineering plastic layer are compounded together to form a composite film; and (2) carrying out molding treatment on the composite membrane to form the composite diaphragm, wherein the engineering plastic layer is attached to a molding die in the molding treatment, so that the problem is solved.
In a first aspect, a method for preparing a composite diaphragm of a sound generating device is provided, which includes the following steps:
compounding the nitrile rubber layer and the engineering plastic layer together to form a composite film;
and carrying out molding treatment on the composite membrane to form a composite diaphragm, wherein in the molding treatment, the engineering plastic layer is attached to a molding die.
In the embodiment of the application, the nitrile rubber layer is made of butadiene-acrylonitrile copolymer, wherein the mass of acrylonitrile is 20-40% of the total mass of the butadiene-acrylonitrile copolymer, such as 20%, 22%, 25%, 28%, 30%, 32%, 35%, 38%, 40% and any value therebetween. According to the invention, the mass of acrylonitrile is controlled to be 20-40% of the total amount of the butadiene-acrylonitrile copolymer, so that the diaphragm has good low-temperature resilience and chemical resistance. If the content of the monomer is more than 40%, the glass transition temperature of the butadiene-acrylonitrile copolymer is easily increased, the low-temperature resilience of the butadiene-acrylonitrile copolymer is reduced, and the low-temperature service life of a diaphragm product is influenced; if less than 20%, the chemical resistance of the butadiene-acrylonitrile copolymer decreases, the vulcanization efficiency decreases, the modulus decreases, and the long-term use temperature decreases.
Specifically, the molecular structure of the butadiene-acrylonitrile copolymer is as follows:
Figure 254833DEST_PATH_IMAGE001
in the above formula, x, y, z are natural numbers.
In the embodiment of the application, the butadiene-acrylonitrile rubber layer is made of butadiene-acrylonitrile copolymer through a cross-linking reaction to form a cross-linked polymer, so that the damping property and the resilience of the composite diaphragm can be improved, the deformation and damage of the production process of the product can be reduced, and the listening quality of the product can be improved.
In the embodiment of the application, the butadiene-acrylonitrile copolymer is further mixed with an inorganic filler reinforcing agent, and the strength of the vibrating diaphragm can be enhanced by adding the inorganic filler reinforcing agent. The inorganic filler reinforcing agent is at least one of silica, silicate, carbonate and amorphous carbon, but is not limited thereto, and may be other inorganic filler reinforcing agents not listed in the embodiment but known to those skilled in the art.
In the embodiment of the present application, when the mass fraction of the butadiene-acrylonitrile copolymer is 100 parts, the mass fraction of the inorganic filler reinforcing agent is 0 to 50 parts, that is, the mass of the inorganic filler reinforcing agent is 0 to 50% of the total amount of the butadiene-acrylonitrile copolymer. If the elastic modulus is more than 50%, the low-temperature rebound resilience of the nitrile rubber layer is easy to reduce, and the vibrating diaphragm folding ring is easy to damage and lose efficacy in the low-temperature use process.
In the embodiment of the application, a cross-linking agent is also mixed in the butadiene-acrylonitrile copolymer, and the addition of the cross-linking agent is helpful for forming cross-linking points in the butadiene-acrylonitrile copolymer and improving the cross-linking degree of the copolymer.
In the examples of the present application, the kind of the crosslinking agent is not particularly limited, and may be a general crosslinking agent known to those skilled in the art, and the crosslinking agent includes at least one of a sulfur-type crosslinking agent, a peroxide-type crosslinking agent, an alkyl phenol resin crosslinking agent, and a thiuram polysulfide, for example.
In the embodiment of the present application, when the mass fraction of the butadiene-acrylonitrile copolymer is 100 parts, the mass fraction of the crosslinking agent is 0.5 to 10 parts, that is, the mass of the crosslinking agent is 0.5 to 10% of the total amount of the butadiene-acrylonitrile copolymer. If the mass of the cross-linking agent is less than 0.5%, the vulcanization efficiency of the nitrile rubber layer is low, the production efficiency of the product is affected, the cross-linking degree is small, and the product is easy to deform in an unrecoverable manner in the vibration process, so that the product fails; if the mass of the cross-linking agent is more than 10%, the cross-linking degree is easily too high, and the film is easily broken and fails in the low-temperature reliability verification process of the product.
In the embodiment of the application, other auxiliary agents can be mixed in the butadiene-acrylonitrile copolymer, and the other auxiliary agents can be a vulcanization auxiliary agent, an anti-aging agent, a plasticizer, a coloring agent and the like.
The butadiene-acrylonitrile copolymer is 100 parts by mass, and the other additives are 0.5-15 parts by mass, that is, the content of the other additives is 0.5-15% of the total amount of the butadiene-acrylonitrile copolymer, such as 0.5%, 2%, 5%, 8%, 10%, 12%, 15% and any value therebetween.
The vulcanization aid mainly improves the vulcanization efficiency of the nitrile rubber and reduces the vulcanization time. In the examples of the present application, the kind of the vulcanization aid is not particularly limited, and may be a general vulcanization aid known to those skilled in the art, and the vulcanization aid is at least one of 2-mercaptobenzothiazole, dibenzothiazyl disulfide, N-cyclohexyl-2-benzothiazylsulfenamide, tetramethylthiuram disulfide, bis 1, 5 pentylenethiuram tetrasulfide, zinc diethyldithiocarbamate, zinc dibutyldithiocarbamate, and diphenylguanidine.
The anti-aging agent is mainly used for improving the thermal oxidation/photo-oxidation aging performance of the nitrile rubber and prolonging the service life of the nitrile rubber. In the present embodiment, the kind of the antioxidant is not particularly limited, and may be a kind of a commonly used antioxidant known to those skilled in the art, and the antioxidant may include at least one of antioxidant N-445, antioxidant 246, antioxidant 4010, antioxidant SP, antioxidant RD, antioxidant ODA, antioxidant OD, and antioxidant WH-02, for example.
The plasticizer is mainly used for improving the mixing property of the nitrile rubber and improving the processability of the nitrile rubber. The kind of the plasticizer is not particularly limited, and may be a general plasticizer known to those skilled in the art.
The coloring agent is added according to the color requirements of different products.
More specifically, the preparation method of the nitrile rubber layer comprises the following steps: preparing a membrane body by adopting butadiene-acrylonitrile copolymer through a film forming process, and drying the membrane body at low temperature to form an uncrosslinked rubber layer or a semi-crosslinked rubber layer; or the membrane body is made by a calendaring process, and the membrane body is an uncrosslinked rubber layer.
In the examples of the present application, the film formation process is not particularly limited, and a film formation process known to those skilled in the art can be used. Preferably, the film forming process may employ a calendaring process or a coating process.
Specifically, the nitrile rubber layer can be made into a membrane body by adopting a calendering process, the membrane body is an uncrosslinked rubber layer, and the membrane body is attached to an engineering plastic layer to form a composite membrane; or dissolving the nitrile rubber in a solvent, preparing a membrane body through a coating process, drying the membrane body at low temperature to form an uncrosslinked rubber layer or a semi-crosslinked rubber layer, and attaching the rubber layer or the semi-crosslinked rubber layer to an engineering plastic layer to form a composite membrane; or dissolving the nitrile rubber in a solvent, and directly coating the nitrile rubber on an engineering plastic film to form the composite film. It is understood that the compounding method includes, but is not limited to, the above-listed compounding methods, and other compounding methods not listed in the present embodiment but known to those skilled in the art may be used.
In the embodiment of the present application, the specific drying temperature for the low-temperature drying is not particularly limited, and those skilled in the art can set the drying temperature according to actual needs as long as the film body is not chemically crosslinked or semi-chemically crosslinked during the drying process. Preferably, the temperature of the low-temperature drying is 80-100 ℃, and more preferably, the temperature of the low-temperature drying is 85-90 ℃.
In the embodiment of the application, the nitrile rubber layer is formed by adopting a coating process or a rolling process, so that chemical crosslinking or semi-chemical crosslinking is not generated; and in the process of forming the composite membrane, chemical crosslinking and shaping are carried out. The nitrile rubber layer is in an uncrosslinked or semi-crosslinked state when the engineering plastic and the nitrile rubber layer are bonded, and the nitrile rubber is not in a net structure but in a linear structure, so that the nitrile rubber is more easily infiltrated with the engineering plastic; and the nitrile rubber layer is vulcanized in the vibrating diaphragm forming process, and can be further infiltrated in the vulcanizing process, so that the bonding force of the nitrile rubber layer and the vibrating diaphragm is further increased. Therefore, the composite vibrating diaphragm can obviously increase the bonding force between the engineering plastic layer and the nitrile rubber layer, improves the reliability of the conventional composite vibrating diaphragm structure, and does not have the problem of layering and even breaking after long-term vibration. Compared with the traditional composite diaphragm of an engineering plastic layer and a glue film layer, the stripping force is obviously improved, and an unexpected technical effect is achieved.
In the embodiment of the application, the shaping is handled for atmospheric pressure shaping or compression molding, just in the shaping, the laminating of engineering plastic layer has improved the problem of nitrile rubber individual layer vibrating diaphragm drawing of patterns difficulty in the forming process through above-mentioned setting on forming die, reduces the deflection when the vibrating diaphragm drawing of patterns, guarantees that the overall dimension of vibrating diaphragm satisfies design and operation requirement.
In the prior art, in order to solve the problem of mold sticking of rubber in the molding process, an internal mold release agent is usually added into the rubber to improve the processability of the rubber. However, when the amount of the internal mold release agent is small, the problem of improving the mold sticking is difficult to achieve, and when the amount of the internal mold release agent is too large, the performance of the manufactured diaphragm is adversely affected, so that the operation is complicated, and the quality of the product is difficult to control. The invention changes the tradition, creatively selects to compound the nitrile rubber layer and the engineering plastic layer together to form a composite film; the composite membrane is formed into a composite diaphragm through molding treatment, and the engineering plastic layer is attached to a molding die in the molding treatment, so that the method is simple and convenient to operate, and the quality of a diaphragm product is easy to control.
The air pressure molding or the compression molding can be selected according to the structure of the composite diaphragm.
In the air pressure molding, there is only one air pressure molding die provided in a shape corresponding to the structure of the diaphragm. In the press molding, a molding die generally includes an upper die and a lower die.
If the composite vibrating diaphragm is of a 2-layer structure, namely the composite vibrating diaphragm consists of a butyronitrile rubber layer and an engineering plastic layer, the molding treatment is air pressure molding, specifically, firstly, a composite film is placed on a molding die, so that the engineering plastic layer in the composite film is attached to the molding die, and the butyronitrile rubber layer is positioned on one side, away from the molding die, of the engineering plastic layer; then, the molding die is placed in a closed cavity, and the closed cavity is charged with gas, such as air, nitrogen, or the like, and heated to perform high-temperature, high-pressure molding.
If the composite diaphragm is of a structure with more than 2 layers, the molding treatment can be air pressure molding or compression molding.
In the examples of the present application, the thickness of the nitrile rubber layer is 5-100 μm, such as 5 μm, 10 μm, 15 μm, 30 μm, 50 μm, 60 μm, 80 μm, 90 μm, 100 μm and any value therebetween.
Repeated research shows that the thickness of the nitrile rubber layer has important influence on the performance of the composite diaphragm, if the thickness of the nitrile rubber layer is less than 5um, the damping performance of the composite diaphragm is reduced, and THD (Total Harmonic Distortion) is increased; if the thickness of the nitrile rubber layer is larger than 100um, the weight of the composite diaphragm is too large, and the sensitivity is poor. Therefore, the thickness of the nitrile rubber layer is controlled within a specific range of 5-100 mu m, and the composite diaphragm has good damping performance and high sensitivity.
In the embodiment of the application, the hardness of the nitrile rubber layer is 25-75A. If the hardness of the nitrile rubber layer is lower than 25A, the modulus is small, and the high-temperature resistance is poor; if the hardness of the nitrile rubber layer is higher than 75A, the product is easy to fail due to easy film breaking in low-temperature reliability verification, and the defects are caused by excessive fillers in the formula.
According to the invention, the vibrating diaphragm compounds the ethylene propylene rubber layer and the engineering plastic layer to form a composite structure, and the inventor finds that the composite structure has complementary functions and synergistic interaction, obtains unexpected technical effects, can obviously reduce the polarization of the vibrating diaphragm, can improve the modulus of the composite vibrating diaphragm to 30-2000MPa, can reduce the thickness of the vibrating diaphragm to 6-100 mu m, reduces the quality of the composite vibrating diaphragm, and effectively improves the sensitivity of the vibrating diaphragm.
In the embodiment of the present application, the material of the engineering plastic layer is not particularly limited, and a common engineering plastic known to those skilled in the art may be used, and the material of the engineering plastic layer is at least one of polyamide, polycarbonate, polyoxymethylene, polyethylene terephthalate, polybutylene terephthalate, polyarylsulfone, polyethersulfone, polyimide, polyphenylene sulfide, polyarylate, polyphenylene ether, polyaryletherketone, and polyetheretherketone, for example.
In the embodiment of the application, the thickness of the engineering plastic layer is 1-30 μm, such as 1 μm, 5 μm, 8 μm, 10 μm, 12 μm, 15 μm, 18 μm, 20 μm, 25 μm, 30 μm and any value therebetween. If the thickness of the engineering plastic layer is less than 1 mu m, the production process of the engineering plastic is difficult to control, the mass production is poor, and the thickness uniformity is difficult to ensure; if the thickness of the engineering plastic layer is more than 30 mu m, the composite diaphragm has high modulus, the product F0 is high, and the low-frequency performance of the diaphragm is poor.
In the embodiment of the present application, the composite diaphragm may have a 2-layer, 3-layer or multi-layer structure, wherein at least one layer is a nitrile rubber layer, and at least one layer is an engineering plastic layer, and those skilled in the art can select a more preferable number of layers according to actual needs.
Specifically, in an embodiment of the present application, the diaphragm has a 2-layer structure, and the diaphragm is composed of a layer of nitrile rubber layer and a layer of engineering plastic layer.
In another embodiment of the present application, the diaphragm is of a 3-layer structure, and the diaphragm includes a layer of nitrile rubber layer and two layers of engineering plastic layers, wherein the engineering plastic layers are respectively disposed on the upper and lower surfaces of the nitrile rubber layer.
The thicknesses of the two engineering plastic layers can be the same or different.
In another embodiment of the present application, the diaphragm may further include a thermoplastic elastomer layer, where the thermoplastic elastomer layer is one of the surface layers of the composite diaphragm, and the thermoplastic elastomer layer is connected to the nitrile rubber layer.
In the embodiment of the present application, the material of the thermoplastic elastomer layer is at least one selected from polyester thermoplastic elastomers, polyurethane thermoplastic elastomers, polyamide thermoplastic elastomers, polystyrene thermoplastic elastomers, and polyolefin thermoplastic elastomers.
In a second aspect, a composite diaphragm of a sound generating device is provided, which is prepared by the preparation method of the first aspect.
In a third aspect, a sound generating device is provided, which includes a sound generating device main body and a composite diaphragm in the first aspect, wherein the composite diaphragm is disposed on the sound generating device main body, and the composite diaphragm is configured to generate sound by vibration.
In order to better understand the technical solutions, the technical solutions will be described in detail with reference to specific examples, which are only preferred embodiments of the present invention and are not intended to limit the present invention.
Example 1
As shown in fig. 1, a composite diaphragm of a sound generating device is composed of an engineering plastic layer 101 and a nitrile rubber layer 102 which are sequentially laminated.
The preparation method of the composite diaphragm comprises the following steps:
s1, attaching a nitrile rubber layer 102 and an engineering plastic layer 101 to form a composite film; the nitrile rubber layer 102 is made of butadiene-acrylonitrile copolymer through a calendering process to form a membrane body, and the membrane body is an uncrosslinked rubber layer;
s2, carrying out air pressure forming treatment on the composite membrane, wherein in the air pressure forming, the engineering plastic layer 101 is attached to a forming mold, and the nitrile rubber layer 102 is located on one side, away from the forming mold, of the engineering plastic layer 101.
The thickness of the nitrile rubber layer 102 is 50 μm; the hardness of the nitrile rubber layer 102 is 50A.
The engineering plastic layer 101 is made of polycarbonate; the thickness of the engineering plastic layer 101 is 5 μm.
Example 2
As shown in fig. 2, a composite diaphragm of a sound generating apparatus includes a first engineering plastic layer 201, a nitrile rubber layer 202, and a second engineering plastic layer 203, which are sequentially stacked.
The preparation method of the diaphragm comprises the following steps:
s1, attaching a first engineering plastic layer 201, a nitrile rubber layer 202 and a second engineering plastic layer 203 to form a composite film; the butadiene-acrylonitrile rubber layer 202 is prepared into a membrane body by adopting butadiene-acrylonitrile copolymer through a coating process, and the membrane body is dried at low temperature to form an uncrosslinked rubber layer or a semi-crosslinked rubber layer; the low-temperature drying temperature is 80 ℃;
s2, right the composite film is subjected to compression molding treatment, and in the compression molding, the first engineering plastic layer 201 is attached to a forming die.
The thickness of the nitrile rubber layer 202 is 30 μm; the hardness of the nitrile rubber layer 202 is 25A.
The first engineering plastic layer 201 is made of polyether-ether-ketone, and the second engineering plastic layer 203 is made of polybutylene terephthalate.
The thickness of the first engineering plastic layer 201 is 5 μm; the thickness of the second engineering plastic layer 203 is 5 μm.
Example 3
As shown in fig. 3, a composite diaphragm of a sound generating apparatus includes an engineering plastic layer 301, a nitrile rubber layer 302, and a thermoplastic elastomer layer 303, which are sequentially stacked.
The preparation method of the diaphragm comprises the following steps:
s1, attaching an engineering plastic layer 301, a nitrile rubber layer 302 and a thermoplastic elastomer layer 303 to form a composite film; the nitrile rubber layer 302 is prepared into a membrane body by adopting butadiene-acrylonitrile copolymer through a coating process, and the membrane body is dried at low temperature to form an uncrosslinked rubber layer or a semi-crosslinked rubber layer; the low-temperature drying temperature is 85 ℃;
s2, carrying out air pressure forming treatment on the composite film, wherein in the air pressure forming, the engineering plastic layer 301 is attached to a forming die.
The thickness of the nitrile rubber layer 302 is 100 micrometers; the hardness of the nitrile rubber layer 302 is 75A.
The engineering plastic layer 301 is made of polyamide and polyarylsulfone.
The thickness of the engineering plastic layer 301 is 5 μm.
The thermoplastic elastomer layer 303 is made of polyester thermoplastic elastomer.
The thickness of the thermoplastic elastomer layer 303 is 20 μm.
Comparative example 1
Based on example 2, the difference is only that: comparative example 1 contained no engineering plastic layer.
Comparative example 2
Based on example 1, the difference is only that: in the air pressure molding in comparative example 2, the nitrile rubber layer 102 was attached to a molding die.
Test example
In order to verify the product performance of the invention, the warpage degree of the diaphragms in examples 1-3 and comparative examples 1-2 was tested, and the specific test method was as follows: the tester comprises three parts: the device comprises a test probe, a display and a granite platform, wherein the test probe is a non-contact displacement sensor; the product is placed on three supporting points of a granite platform, an upper test probe and a lower test probe synchronously scan the product according to the same track, the distance from the test probes to the nearest surface of the product is recorded, the difference value of the two test probes of each test point is obtained, wherein one half of the difference value is the test value of the warping degree of the test point, and the test value of the maximum warping degree in each test point is defined as the warping degree of the product. 100 parallel products were produced for each example according to the production methods of examples 1 to 3 and comparative examples 1 to 2, the warpage of each parallel product was measured, and the distribution of the warpage of each parallel product was counted, and the measurement results are shown in table 1.
TABLE 1 results of diaphragm warpage
Warping degree of diaphragm is less than 3 filaments Diaphragm warping degree 3-5 silk 5-8 silk of diaphragm warpage Diaphragm warping degree 8-10 silk The warping degree of the diaphragm is more than 10 filaments
Example 1 17% 61% 14% 5% 3%
Example 2 20% 63% 12% 4% 1%
Example 3 18% 60% 15% 5% 2%
Comparative example 1 4% 7% 15 38% 36%
Comparative example 2 6% 8% 20% 36% 30%
As can be seen from the table 1, the composite diaphragm is in the molding process, the engineering plastic layer is attached to the molding die, the problem that the composite diaphragm is difficult to demold in the molding process is solved through the arrangement, and the deformation of the diaphragm during demolding is reduced.
In order to verify the product performance of the invention, the normal temperature modulus tests of the diaphragms in the examples 1 to 3 and the comparative example 1 are carried out, and the test results show that the normal temperature modulus of the diaphragms in the examples 1 to 3 and the comparative example 1 is 546MPa, 717MPa, 730MPa and 19MPa respectively.
To verify the performance of the product of the present invention, FR curves of the diaphragms in example 2 and comparative example 1 are tested, and specific results are shown in fig. 4, where fig. 4 is a frequency response curve (FR curve) of the diaphragm provided in example 2 of the present invention and the diaphragm in comparative example 1, a dotted line is the FR curve of the diaphragm provided in example 2 of the present invention, and a solid line is the FR curve of the diaphragm in comparative example 1.
As can be seen from fig. 4, the sensitivity of the composite diaphragm of the present invention is significantly improved compared to the single-layer diaphragm of comparative example 1.
The above-mentioned embodiments only express the embodiments of the present invention, and the description is more specific and detailed, but not understood as the limitation of the patent scope of the present invention, but all the technical solutions obtained by using the equivalent substitution or the equivalent transformation should fall within the protection scope of the present invention.

Claims (12)

1. A preparation method of a composite diaphragm of a sound production device is characterized by comprising the following steps:
compounding the nitrile rubber layer and the engineering plastic layer together to form a composite film;
forming the composite membrane to form a composite vibrating membrane, wherein the engineering plastic layer is attached to a forming mold in the forming process;
the butadiene-acrylonitrile rubber layer is made of butadiene-acrylonitrile copolymer, wherein the mass of acrylonitrile is 20-40% of the total mass of the butadiene-acrylonitrile copolymer.
2. The method for preparing the composite diaphragm of the sound generating device according to claim 1, wherein the method for preparing the nitrile rubber layer comprises the following steps: preparing a membrane body through a coating process, and drying the membrane body at low temperature to form an uncrosslinked rubber layer or a semi-crosslinked rubber layer; or the membrane body is made by a calendaring process, and the membrane body is an uncrosslinked rubber layer.
3. The method for preparing a composite diaphragm of a sound generating apparatus according to claim 1, wherein the molding process is air pressure molding or compression molding.
4. The method for preparing a composite diaphragm of a sound generating device according to claim 1, wherein the butadiene-acrylonitrile copolymer is further mixed with an inorganic filler reinforcing agent, and the inorganic filler reinforcing agent is at least one of silicon oxide, silicate, carbonate and amorphous carbon; the inorganic filler reinforcing agent accounts for 0-50% of the total weight of the butadiene-acrylonitrile copolymer.
5. The method for preparing a composite diaphragm of a sound generating device according to claim 1, wherein the butadiene-acrylonitrile copolymer is further mixed with a cross-linking agent, and the cross-linking agent comprises at least one of a sulfur type cross-linking agent, a peroxide cross-linking agent, an alkyl phenol resin cross-linking agent, and thiuram polysulfide; the mass of the cross-linking agent is 0.5-10% of the total mass of the butadiene-acrylonitrile copolymer.
6. The method for preparing a composite diaphragm of a sound generating apparatus according to claim 1, wherein the thickness of the nitrile rubber layer is 5 to 100 μm; the hardness of the nitrile rubber layer is 25-75A.
7. The method for preparing a composite diaphragm of a sound generating device according to claim 1, wherein the engineering plastic layer is made of at least one of polyamide, polycarbonate, polyoxymethylene, polyethylene terephthalate, polybutylene terephthalate, polyarylsulfone, polyethersulfone, polyimide, polyphenylene sulfide, polyarylate, polyphenylene ether, polyaryletherketone, and polyetheretherketone; the thickness of the engineering plastic layer is 1-30 μm.
8. The method for preparing a composite diaphragm of a sound generating device according to claim 1, wherein the composite diaphragm comprises two engineering plastic layers and a nitrile rubber layer, and the two engineering plastic layers are respectively disposed on two surfaces of the nitrile rubber layer.
9. The method for preparing a composite diaphragm of a sound generating device according to claim 1, wherein the composite diaphragm further comprises a thermoplastic elastomer layer, the thermoplastic elastomer layer is one of the surface layers of the diaphragm, and the thermoplastic elastomer layer is connected with the nitrile rubber layer.
10. The method for manufacturing a composite diaphragm of a sound generating apparatus as claimed in claim 9, wherein the thermoplastic elastomer layer is made of at least one of a polyester-based thermoplastic elastomer, a polyurethane-based thermoplastic elastomer, a polyamide-based thermoplastic elastomer, a polystyrene-based thermoplastic elastomer, and a polyolefin-based thermoplastic elastomer.
11. A composite diaphragm for a sound-generating apparatus, which is produced by the production method according to any one of claims 1 to 10.
12. A sound generating device comprising the composite diaphragm of claim 11.
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