CN111923527A

CN111923527A - Composite diaphragm of loudspeaker, preparation method of composite diaphragm and loudspeaker

Info

Publication number: CN111923527A
Application number: CN202011012751.7A
Authority: CN
Inventors: 周厚强; 闫付臻; 李春
Original assignee: Goertek Inc
Current assignee: Goertek Inc
Priority date: 2020-09-23
Filing date: 2020-09-23
Publication date: 2020-11-13

Abstract

The invention discloses a composite diaphragm of a loudspeaker, a preparation method thereof and the loudspeaker, wherein the preparation method comprises the following steps: compounding the polysulfide rubber layer and the thermoplastic elastomer layer together to form a composite film; and carrying out molding treatment on the composite membrane to form the composite diaphragm, wherein in the molding treatment, the thermoplastic elastomer layer is attached to a molding die. According to the composite diaphragm, the polysulfide rubber layer and the thermoplastic elastomer layer are compounded to form the composite structure, the inventor finds that the composite structure has complementary functions and synergistic interaction, an unexpected technical effect is obtained, the problem that demolding is difficult due to the fact that the polysulfide rubber single-layer diaphragm is easily attached to a mold in the forming process can be solved, the medium-frequency sensitivity is remarkably improved, the composite diaphragm has good resilience and rigidity, the composite diaphragm can be automatically recovered after stressed contact deformation in the turnover process, and the yield of the diaphragm turnover process is remarkably improved.

Description

Composite diaphragm of loudspeaker, preparation method of composite diaphragm and loudspeaker

Technical Field

The invention relates to the field of acoustic products, in particular to a composite diaphragm of a loudspeaker, a preparation method of the composite diaphragm and the loudspeaker.

Background

A loudspeaker for converting electrical energy into acoustic energy generally comprises a housing having a basin-like structure, and a vibration system and a magnetic circuit system accommodated in an inner cavity defined by the housing, the vibration system including a diaphragm and a voice coil connected together. The loudspeaker diaphragm is the main component of the loudspeaker, and the loudspeaker (especially a midbass loudspeaker) converts electromagnetic force to the diaphragm tightly connected with the loudspeaker diaphragm through a voice coil at the center of the diaphragm to form mechanical force so as to generate sound to complete the electric-force-sound conversion. The diaphragm is the central mechanical part and the most important part in the electro-acoustic-electro-acoustic conversion process, and can affect the acoustic performance of the loudspeaker.

The diaphragm of the existing loudspeaker mostly adopts polysulfide rubber single-layer diaphragm, the polysulfide rubber single-layer diaphragm has the characteristics of good oil resistance, heat resistance, abrasion resistance, damping property, rebound resilience, waterproofness and the like, and the processing technology is simple, so that the polysulfide rubber single-layer diaphragm is widely applied to the existing loudspeaker products.

However, the polysulfide rubber single-layer diaphragm at least has the following technical problems: the polysulfide rubber single-layer diaphragm is easy to be tightly attached to a mold in the molding process, so that the diaphragm is difficult to take out, and meanwhile, the diaphragm is stretched and deformed in the film taking process, so that the yield of products is seriously influenced; in addition, the modulus of the polysulfide rubber is 0.7-10 MPa, the modulus is small, and when the polysulfide rubber is used in a loudspeaker, the thickness of F0 required by the polysulfide rubber is usually thick, so that the weight is too heavy, and the medium-frequency sensitivity of a product is reduced.

In order to solve the technical problems, researchers point out that the polysulfide rubber layer and the engineering plastic layer are compounded to form the composite vibrating diaphragm, so that the problem that demolding is difficult due to the fact that the polysulfide rubber single-layer vibrating diaphragm is easily attached to a mold in the molding process can be solved, and the sensitivity of the vibrating diaphragm is improved.

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: the composite diaphragm formed by compounding the polysulfide rubber layer and the engineering plastic layer has low elongation at break and poor rebound resilience, so that the waterproof performance of the diaphragm product is reduced; and the vibrating diaphragm is easy to produce unrecoverable deformation in the process of turnover, the reject ratio is high, and the product cost is increased invisibly.

Therefore, provide a composite diaphragm, not only can improve polysulfide rubber individual layer vibrating diaphragm and easily lead to the difficult problem of drawing of patterns with the mould laminating in forming process, improve sensitivity, have had resilience and rigidity concurrently moreover, reduce the deformation of vibrating diaphragm turnover in-process, guarantee the quality, reduce the defective rate, become the technological problem that this field is waited for to solve urgently.

Disclosure of Invention

In order to overcome the defects of polysulfide rubber diaphragms in the prior art, the invention mainly aims to provide a composite diaphragm of a loudspeaker, a preparation method thereof and the loudspeaker.

The technical problem to be solved by the invention is realized by the following technical scheme:

in a first aspect of the present invention, a method for preparing a composite diaphragm of a speaker is provided, which includes the following steps:

compounding the polysulfide rubber layer and the thermoplastic elastomer layer together to form a composite film;

and carrying out molding treatment on the composite membrane to form the composite diaphragm, wherein in the molding treatment, the thermoplastic elastomer layer is attached to a molding die.

Optionally, the polysulfide rubber layer is made of a copolymer obtained by polycondensation of an organic chlorine monomer and an inorganic polysulfide.

Alternatively, the molecular structure of the copolymer is as follows:

in the above molecular structural formula, R is a divalent organic group; l is a polysulfide rubber molecular chain segment; x is any one of thiol, hydroxyl, halogen, amino and amide; m is 1 or 2.

Alternatively, the R comprises any one of the following divalent organic groups:

、

、

。

optionally, a cross-linking agent is further mixed in the polysulfide rubber, the cross-linking agent is at least one of metal oxide, peroxide and oxidant, and the mass of the cross-linking agent is 0.5-5% of that of the polysulfide rubber.

Optionally, the polysulfide rubber is also mixed with a filler, and the filler adopts at least one of carbon materials, silicon oxide, silicate, carbonate, sulfate and metal oxide; the filler accounts for 0.1-50% of the mass of the polysulfide rubber.

Optionally, an auxiliary agent is further mixed in the polysulfide rubber, and the auxiliary agent comprises at least one of an anti-aging agent, a plasticizer, a tackifier and a coloring agent; the content of the auxiliary agent is 1-15% of the polysulfide rubber.

Optionally, the hardness of the polysulfide rubber layer is 20-85A, the loss factor of the polysulfide rubber at room temperature is 0.1-1, and the storage modulus of the polysulfide rubber layer at room temperature is 1-15 MPa.

Alternatively, the material of the thermoplastic elastomer layer includes at least one of a styrene-based thermoplastic elastomer, an olefin-based thermoplastic elastomer, a diene-based thermoplastic elastomer, a vinyl chloride-based thermoplastic elastomer, a urethane-based thermoplastic elastomer, an ester-based thermoplastic elastomer, an amide-based thermoplastic elastomer, an organic fluorine-based thermoplastic elastomer, a silicone-based thermoplastic elastomer, and an ethylene-based thermoplastic elastomer.

Optionally, the preparation method of the polysulfide 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 surface of the thermoplastic elastomer layer is subjected to a surface activation treatment.

Optionally, the polysulfide rubber layer and the thermoplastic elastomer layer are compounded together by thermal bonding, or the polysulfide rubber layer is directly coated on the surface of the thermoplastic elastomer layer and compounded together after drying to form the composite film.

Optionally, the molding process is air pressure molding or compression molding.

According to another aspect of the present invention, there is provided a composite diaphragm for a loudspeaker, which is prepared by the above preparation method.

According to another aspect of the present invention, there is provided a loudspeaker including the composite diaphragm described above.

The invention has the following beneficial effects:

according to the composite diaphragm, the polysulfide rubber layer and the thermoplastic elastomer layer are compounded to form the composite structure, the inventor finds that the composite structure has complementary functions and synergistic interaction, an unexpected technical effect is obtained, the problem that demolding is difficult due to the fact that the polysulfide rubber single-layer diaphragm is easily attached to a mold in the forming process can be solved, the medium-frequency sensitivity is remarkably improved, the composite diaphragm has good resilience and rigidity, the composite diaphragm can be automatically recovered after stressed contact deformation in the turnover process, and the yield of the diaphragm turnover process is remarkably improved.

Drawings

FIG. 1 is a graph showing the effect of the mass of filler on the tensile strength and elongation at break of a polysulfide rubber;

FIG. 2 is a total harmonic distortion test curve of the diaphragm provided in example 1 of the present invention and the diaphragm in comparative example 1

Fig. 3 is a test curve of loudness of different frequencies of the diaphragm provided in example 1 of the present invention and the diaphragm in 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, in the prior art, the composite diaphragm formed by compounding the polysulfide rubber layer and the engineering plastic layer has low elongation at break and poor rebound resilience, which leads to the decrease of the waterproof performance of the diaphragm product; and the vibrating diaphragm is easy to generate unrecoverable deformation in the process of turnover, the reject ratio is high, and the product cost is increased virtually, but the problem is not noticed. In order to solve the technical problem, the invention provides a composite diaphragm of a loudspeaker, a preparation method of the composite diaphragm and the loudspeaker.

In a first aspect, a method for preparing a composite diaphragm of a loudspeaker is provided, which includes the following steps:

In the invention, the polysulfide rubber layer and the thermoplastic elastomer layer are compounded by the composite vibrating diaphragm to form a composite structure, and the thermoplastic elastomer layer is attached to a forming die in the forming treatment. Because the thermoplastic elastomer is high in modulus at normal temperature and good in temperature resistance, the thermoplastic elastomer layer is adhered to the forming die for forming, the problem that the polysulfide rubber layer is adhered to the forming die can be effectively avoided, the die is easy to take, the tensile deformation of the vibrating diaphragm in the die taking process is reduced, and the yield of products is improved.

According to the composite vibrating diaphragm, the polysulfide rubber layer and the thermoplastic elastomer layer are compounded to form the composite structure, the inventor finds that the composite structure has complementary functions and synergistic interaction, an unexpected technical effect is achieved, the modulus of the vibrating diaphragm is greatly improved, the thickness of the vibrating diaphragm is effectively reduced, the medium-frequency sensitivity is effectively improved, meanwhile, the composite vibrating diaphragm has good resilience and rigidity, the composite vibrating diaphragm can automatically recover after stressed contact deformation in the turnover process, and the yield of the vibrating diaphragm in the turnover process is remarkably improved.

In the invention, the polysulfide rubber layer is made of a copolymer, wherein the copolymer is formed by polycondensation of an organic chlorine monomer and an inorganic polysulfide.

In the present invention, the kind of the organic chloride monomer is not particularly limited, and may be a general one known to those skilled in the art, and preferably, the organic chloride monomer includes at least one of dichloroethane, dichloropropane, dichlorodiethyl ether, dichloroethylformal, dichlorobutylformal, dichlorobutyl ether, and trichloropropane.

In the present invention, the kind of the inorganic polysulfide is not particularly limited, and may be a general inorganic polysulfide known to those skilled in the art, and preferably, the inorganic polysulfide is sodium polysulfide.

In the present invention, the molecular structural formula of the copolymer is as follows:

Wherein R comprises any one of the following divalent organic groups:

、

、

。

as can be seen from the molecular structural formula of the above copolymer: the molecular chain of the copolymer is saturated, and the main chain of the copolymer has sulfur atoms. The diaphragm prepared by adopting the copolymer to prepare the polysulfide rubber layer has good oil resistance, solvent resistance, aging resistance, low air permeability and good temperature resistance, the use temperature can reach-50 to 150 ℃, and the diaphragm can be used for a long time at 130 ℃ in a dye oil medium.

In the present invention, a crosslinking agent is further mixed in the copolymer. The addition of the crosslinking agent helps to form crosslinking points in the copolymer and increases the degree of crosslinking of the copolymer.

In the present invention, the kind of the crosslinking agent is not particularly limited, and may be any crosslinking agent used in a general polysulfide rubber known to those skilled in the art, and the crosslinking agent is preferably at least one of a metal oxide, a peroxide, and an oxidizing agent, but is not limited thereto, and may be any other crosslinking agent not listed in the present embodiment but known to those skilled in the art.

In the present invention, since the molecular chain of the copolymer is saturated, sulfur cannot be used as a crosslinking agent.

As the metal oxide, zinc oxide, lead oxide, magnesium oxide, calcium oxide, barium oxide, iron oxide, cobalt oxide, copper oxide can be given as examples. As the peroxide, there can be exemplified zinc peroxide, lead dioxide, magnesium peroxide, calcium peroxide, manganese dioxide, tellurium dioxide, selenium dioxide, hydrogen peroxide, iron peroxide, arsenic peroxide, antimony trioxide, antimony pentoxide, tin dioxide, lead tetraoxide, potassium peroxide, benzoyl peroxide, dicumyl peroxide, cumene peroxide, t-butyl perbenzoic acid, methyl ethyl ketone peroxide. As the oxidizing agent, there may be exemplified sodium chromate, potassium chromate, sodium dichromate, potassium dichromate, ammonium dichromate, sodium chlorate, potassium chlorate, barium chlorate, sodium borate, ammonium borate, nitrobenzene, dinitrobenzene, trinitrobenzene, trinitrotoluene, p-benzoquinone dioxime.

In the present invention, the mass of the crosslinking agent is 0.5 to 5% of the mass of the polysulfide rubber, for example, 0.5%, 0.8%, 1%, 2%, 3%, 4%, 5%, and any value therebetween. If the mass of the cross-linking agent is less than 0.5 percent of the total amount of the copolymer, the cross-linking degree of the polysulfide rubber layer is low, the rebound resilience is poor, and the polysulfide rubber layer is easy to deform and lose efficacy in a large-amplitude vibration process; if the mass of the cross-linking agent is more than 5% of the total amount of the copolymer, the crosslinking degree of the polysulfide rubber layer is too high, the low-temperature resilience is poor, and the elongation at break is small, so that the low-temperature performance of the vibrating diaphragm is poor, and the diaphragm is easy to break and lose efficacy in the low-temperature reliability process.

In the present invention, the polysulfide rubber is further mixed with a filler. As the polysulfide rubber belongs to amorphous polymers, the self-strength is low, the tensile strength is only 0.5-1.0 MPa, and the self-reinforcing property is not generated in the stretching process. In the invention, the tensile strength, the tearing strength, the wear resistance, the hardness and the like of the polysulfide rubber can be improved by adding the filler.

In the present invention, the filler is at least one of a carbon-based material, silica, silicate, carbonate, sulfate, and metal oxide, but is not limited thereto, and may be other fillers that are not listed in the present embodiment but are known to those skilled in the art.

Among them, carbon-based materials include, but are not limited to, carbon black (furnace black, channel black, thermal black), graphite, graphene, carbon nanotubes, carbon fibers, and the like; for silica, including but not limited to fumed silica, precipitated silica, and the like; for silicates, including but not limited to talc, bentonite, kaolin, china clay, wollastonite, diatomaceous earth, mica, glass fiber; for carbonates, including but not limited to calcium carbonate, magnesium carbonate; for sulfates, including but not limited to calcium sulfate, barium sulfate; for metal oxides, including but not limited to alumina, magnesia, titania.

In the present invention, the mass of the filler is 0.1 to 50% of the mass of the polysulfide rubber, for example, 0.1%, 5%, 8%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, and any value therebetween. As shown in FIG. 1, the effect of the quality of the filler on the tensile strength and elongation at break of the polysulfide rubber is shown. The inventor finds in research that as the content of the filler increases, the hardness, tensile strength, elongation at break, storage modulus, tear property and abrasion resistance of the polysulfide rubber layer increase, but the glass transition temperature increases and the low temperature property becomes worse. In the invention, the mass of the filler is controlled to be 0.1-50% of the total amount of the copolymer, and the good hardness, tensile strength, storage modulus, elongation at break and temperature resistance of the polysulfide rubber layer can be considered.

In the invention, the polysulfide rubber is also mixed with an auxiliary agent, and the auxiliary agent comprises at least one of an anti-aging agent, a plasticizer, a tackifier and a coloring agent. The mass of the auxiliary agent is 1-15% of the mass of the polysulfide rubber, such as 1%, 2.5%, 5%, 8%, 10%, 12%, 15% and any value therebetween.

The anti-aging agent is mainly used for stopping the reaction of free radicals and rubber molecules of polysulfide rubber molecules under the action of thermal oxygen light, so that the service life of the rubber is obviously prolonged, and the performance reduction of the rubber is reduced. In the present invention, the kind of the antioxidant is not particularly limited, and may be any of the usual antioxidants known to those skilled in the art, and examples of the antioxidant include at least one of antioxidant N-445, antioxidant 246, antioxidant 4010, antioxidant SP, antioxidant RD, antioxidant ODA, antioxidant OD and antioxidant WH-02; the mass of the anti-aging agent is 0.5-3% of the total amount of the copolymer.

The plasticizer is mainly used for improving the mixing property of the polysulfide rubber, increasing the molecular chain spacing, reducing the system viscosity and improving the plasticity of the polysulfide rubber. The type of the plasticizer is not particularly limited in the present invention, and may be any of the types of commonly used plasticizers known to those skilled in the art, and preferably, the plasticizer includes at least one of coumarone resin, alkyd resin, liquid polysulfide rubber, coal tar, dibutyl phthalate, dioctyl sebacate, tricresyl phosphate, dioctyl adipate, and epoxidized soybean oil.

The mass of the plasticizer is 1-15% of that of the polysulfide rubber. The larger the mass of the plasticizer is, the better the plasticity of the polysulfide rubber is, but the plasticizer may be caused to migrate to the surface of the rubber to affect the product quality, and the more the plasticizer is, the greater the compression set of the rubber is; if the mass of the plasticizer is small, the plasticity of the polysulfide rubber is poor, and the kneading process is difficult.

The tackifier is used for improving the adhesive force of the polysulfide rubber and avoiding the product failure caused by the delamination of the polysulfide rubber and the thermoplastic elastomer. The kind of the tackifier is not particularly limited in the present invention, and may be any of the kinds of commonly used tackifiers well known to those skilled in the art, and preferably, the tackifier is at least one of methyl methacrylate, butyl methacrylate, vinyl acetate, organotin compound polyester, cyano carboxylate, carbon 5 resin, carbon 9 resin, rosin, and terpene resin.

In the present invention, the material of the thermoplastic elastomer layer is not particularly limited, and may be a common thermoplastic elastomer well known to those skilled in the art, and examples of the material of the thermoplastic elastomer layer include at least one of a styrene-based thermoplastic elastomer, an olefin-based thermoplastic elastomer, a diene-based thermoplastic elastomer, a vinyl chloride-based thermoplastic elastomer, a urethane-based thermoplastic elastomer, an ester-based thermoplastic elastomer, an amide-based thermoplastic elastomer, an organic fluorine-based thermoplastic elastomer, a silicone-based thermoplastic elastomer, and an ethylene-based thermoplastic elastomer.

The F0 of the loudspeaker is related to the Young modulus and the weight of the material, and the F0 of the diaphragm can be adjusted by adjusting the Young modulus of the material and the thickness of the diaphragm, wherein the calculation formula of F0 is as follows:

wherein Mms is the equivalent vibration mass of the sounding device, and Cms is the equivalent compliance of the sounding device. The Young modulus of the material has positive correlation with the hardness of the material, and the higher the modulus of the material is, the higher the hardness of the material is; in order to ensure that the response performance of the diaphragm at low frequency is improved, F0 is generally required to be lower, but the diaphragm also needs to be ensured to have certain rigidity, so that the distortion caused by polarization generated in the vibration process of the large diaphragm is avoided. In the invention, the hardness of the polysulfide rubber layer is 20-85A, and the room-temperature storage modulus of the polysulfide rubber layer is 1-15 MPa, so that the vibrating diaphragm F0 can reach 500-1500 hz, and the low-frequency performance is excellent.

The polysulfide rubber diaphragm has improved damping performance, effectively inhibits the polarization of the diaphragm in the vibration process, and has excellent vibration consistency at each point, so the loss factor of the polysulfide rubber is preferably 0.1-1.0.

In the present invention, the polysulfide rubber layer is formed by a calendering process or a coating process. Specifically, the polysulfide rubber layer is prepared by uniformly mixing a copolymer, a cross-linking agent, a filler and an auxiliary agent, preparing a film body through a coating process, and drying the film body at low temperature to form an uncrosslinked rubber layer or a semi-crosslinked rubber layer; or, the membrane body is made through a calendaring process, and the membrane body is an uncrosslinked rubber layer.

In the invention, the polysulfide rubber layer is molded by adopting a coating process or a calendering 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. Because the polysulfide rubber layer is in an uncrosslinked or semi-crosslinked state when the thermoplastic elastomer layer and the polysulfide rubber layer are attached, the polysulfide rubber is not in a net structure but in a linear structure, and is easier to infiltrate with the thermoplastic elastomer; and the polysulfide 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 polysulfide rubber layer and the vibrating diaphragm is further increased. Therefore, the composite vibrating diaphragm can obviously increase the bonding force between the thermoplastic elastomer layer and the polysulfide rubber layer, improves the reliability of the traditional composite vibrating diaphragm structure, and does not have the problem of layering and even breaking after long-term vibration.

In the present invention, before compounding, the surface of the thermoplastic elastomer layer is subjected to a surface activation treatment. The surface of the thermoplastic elastomer layer is subjected to surface activation treatment, and the polysulfide rubber layer can be better adhered to the surface of the thermoplastic elastomer layer.

The specific process of the surface activation treatment in the present invention is not particularly limited, and various surface activation methods known to those skilled in the art, such as plasma surface activation treatment, can be used.

In the present invention, the polysulfide rubber layer and the thermoplastic elastomer layer may be further compounded together by thermal lamination; the polysulfide rubber layer can also be directly coated on the surface of the thermoplastic elastomer layer and compounded together after being dried to form a 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 invention, the composite diaphragm can be of a 2-layer, 3-layer or multi-layer structure, wherein at least one layer is a polysulfide rubber layer, and at least one layer is a thermoplastic elastomer layer, and a person skilled in the art can select a more optimal number of layers according to actual needs.

Specifically, in one embodiment of the present invention, the composite diaphragm has a 2-layer structure, and the diaphragm is composed of a polysulfide rubber layer and a thermoplastic elastomer layer.

In another embodiment of the present invention, the composite diaphragm has a 3-layer structure, and the diaphragm includes a polysulfide rubber layer and two thermoplastic elastomer layers, wherein the thermoplastic elastomer layers are respectively disposed on the upper and lower surfaces of the polysulfide rubber layer.

The thickness of the two thermoplastic elastomer layers may be the same or different.

It should be noted that, depending on the structure of the composite diaphragm, the air pressure or the compression molding method may be selected, as long as the polysulfide rubber layer is not directly contacted with the molding die.

In the air pressure forming, only one air pressure forming die is provided, and the composite film is completely attached to the die under the action of temperature and pressure to form a shape corresponding to the die. In compression molding, a molding die generally comprises an upper die and a lower die, and a composite film is placed between the two dies to form a diaphragm structure under the action of temperature and pressure.

In a second aspect, a composite diaphragm of a loudspeaker is provided, which is prepared by the preparation method of the first aspect.

In a third aspect, a loudspeaker is provided, comprising the composite diaphragm of the second aspect.

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

A composite vibrating diaphragm of a loudspeaker is composed of a polysulfide rubber layer and a thermoplastic elastomer layer which are sequentially laminated.

The preparation method of the composite diaphragm of the loudspeaker comprises the following steps:

compounding the polysulfide rubber layer and the thermoplastic elastomer layer together through thermal bonding to form a composite film;

and carrying out air pressure forming treatment on the composite membrane to form a composite diaphragm, wherein in the air pressure forming treatment, the thermoplastic elastomer layer is attached to a forming mould.

The preparation method of the polysulfide rubber layer comprises the following steps: the copolymer, the cross-linking agent, the filler and the auxiliary agent are uniformly mixed, and a film body is formed through a calendering process, wherein the film body is an uncrosslinked rubber layer.

The copolymer is formed by polycondensation of an organic chlorine monomer and an inorganic polysulfide, the mass of the cross-linking agent is 3% of that of the polysulfide rubber, the mass of the filler is 30% of that of the polysulfide rubber, and the mass of the auxiliary agent is 12% of that of the polysulfide rubber.

The cross-linking agent is zinc oxide; the filler is graphite; the auxiliary agent comprises an anti-aging agent and a plasticizer, wherein the anti-aging agent is anti-aging agent N-445, and the plasticizer is coumarone resin.

The thermoplastic elastomer layer is made of polyurethane thermoplastic elastomer.

Example 2

The preparation method of the polysulfide rubber layer comprises the following steps: the copolymer, the cross-linking agent, the filler and the auxiliary agent are uniformly mixed, a film body is prepared through a coating process, and the film body is dried at low temperature to form an uncrosslinked rubber layer or a semi-crosslinked rubber layer.

The copolymer is formed by polycondensation of an organic chlorine monomer and an inorganic polysulfide, the mass of the cross-linking agent is 0.5% of that of the polysulfide rubber, the mass of the filler is 0.1% of that of the polysulfide rubber, and the mass of the auxiliary agent is 3% of that of the polysulfide rubber.

The cross-linking agent is zinc peroxide and magnesium peroxide; the filler is fumed silica; the auxiliary agent comprises an anti-aging agent, and the anti-aging agent comprises an anti-aging agent 246 and an anti-aging agent 4010.

The material of the thermoplastic elastomer layer is a styrene thermoplastic elastomer.

Example 3

A composite diaphragm of a loudspeaker is composed of a first thermoplastic elastomer layer, a polysulfide rubber layer and a second thermoplastic elastomer layer which are sequentially laminated.

compounding the first thermoplastic elastomer layer, the polysulfide rubber layer and the second thermoplastic elastomer layer together through thermal bonding to form a composite film;

and carrying out compression molding treatment on the composite membrane to form a composite diaphragm, wherein in the compression molding treatment, the first thermoplastic elastomer layer is attached to a forming mold.

The preparation method of the polysulfide rubber layer comprises the following steps: the copolymer, the cross-linking agent, the filler and the auxiliary agent are uniformly mixed, and then a film body is formed through a calendering process, wherein the film body is an uncrosslinked rubber layer.

The copolymer is formed by polycondensation of an organic chlorine monomer and an inorganic polysulfide, the mass of the cross-linking agent is 0.5% of that of the polysulfide rubber, the mass of the filler is 15% of that of the polysulfide rubber, and the mass of the auxiliary agent is 5% of that of the polysulfide rubber.

The cross-linking agent is magnesium oxide and ferric peroxide; the filler is carbon black and calcium carbonate; the auxiliary agent comprises a plasticizer, and the plasticizer comprises dibutyl phthalate and dioctyl phthalate.

The first thermoplastic elastomer layer and the second thermoplastic elastomer layer are both made of a urethane thermoplastic elastomer.

Comparative example 1

Based on example 1, the difference is only that: comparative example 1 did not contain a thermoplastic elastomer layer.

Comparative example 2

Based on example 1, the difference is only that: in comparative example 2 the thermoplastic elastomer layer was replaced with an engineering plastic layer.

In order to verify the performance of the product of the invention, 100 parallel products were manufactured for each example according to the preparation methods of examples 1 to 3 and comparative examples 1 to 2, and the manufactured diaphragms were subjected to yield loss tests, wherein the yield loss of the diaphragms mainly includes yield loss caused by the adhesive film, yield loss in the turnaround process, and yield loss in the assembly process, and the test results are shown in table 1.

It should be noted that the yield loss caused by the adhesive film means that in the forming process of the vibrating diaphragm, the vibrating diaphragm is difficult to take the film due to the fact that the vibrating diaphragm is tightly attached to the mold, and the yield loss of the product is caused by the stretching deformation in the demolding process of the vibrating diaphragm.

Turnover process yield loss means the vibrating diaphragm drawing of patterns back, at the transfer vibrating diaphragm in-process, because the vibrating diaphragm atress contact produces the yield loss that the deformation that can not resume caused the product.

The yield loss in the assembling process refers to the yield loss of products caused by the difficulty in positioning in the process of assembling the vibrating diaphragm to the sound generating device.

TABLE 1

	Mucosa-caused yield loss%	Turnover process yield loss/%)	Assembly processYield loss/%)	Production yield%
					Example 1	1	1	1	97
Example 2	1	1	1	97
					Example 3	1	0	1	98
Comparative example 1	10	1	3	86
					Comparative example 2	1	6	1	92

As can be seen from table 1, the polysulfide rubber single-layer diaphragm in comparative example 1 is tightly attached to the forming mold, so that the diaphragm is easily stretched and deformed during the mold removing process, and a certain yield loss is caused. Compared with the prior art, the polysulfide rubber and engineering plastic composite film in the comparative example 2 has high modulus at normal temperature, small elongation at break and poor rebound resilience, and when the vibrating diaphragm deforms under external force, creases are easily generated, so that the turnover yield loss is large; the composite film has rebound resilience and rigidity, and the production yield is optimal.

To verify the performance of the product of the present invention, total harmonic distortion test curves of the diaphragms in the embodiment 1 and the comparative example 1 are tested, and specific results are shown in fig. 2, where fig. 2 is a total harmonic distortion test curve of the diaphragm provided in the embodiment 1 of the present invention and the diaphragm in the comparative example 1, a dotted line is a total harmonic distortion test curve of the diaphragm provided in the comparative example 1, and a solid line is a total harmonic distortion test curve of the diaphragm in the embodiment 1. As can be seen from fig. 2, the diaphragm of example 1 of the present invention has a lower THD (total harmonic distortion) than the diaphragm of comparative example 1. This shows that the diaphragm of embodiment 1 of the present invention has better polarization resistance and better sound quality.

In order to verify the performance of the product of the present invention, the test curves (SPL curves) of the loudness of the diaphragms in example 1 and comparative example 1 at different frequencies were tested, with the frequency (Hz) on the abscissa and the loudness on the ordinate. Specific results referring to fig. 3, fig. 3 is a test curve of loudness of the diaphragm of example 1 of the present invention at different frequencies from the diaphragm of comparative example 1, the solid line is the test curve of loudness of the diaphragm of example 1 at different frequencies, and the dotted line is the test curve of loudness of the diaphragm of comparative example 1 at different frequencies.

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

1. A preparation method of a composite diaphragm of a loudspeaker is characterized by comprising the following steps:

2. The method of claim 1, wherein the polysulfide rubber layer is made of a copolymer obtained by polycondensation of an organic chlorine monomer and an inorganic polysulfide.

3. The method for preparing a composite diaphragm of a loudspeaker according to claim 2, wherein the molecular structural formula of the copolymer is as follows:

4. The method for preparing a composite diaphragm of a loudspeaker according to claim 2, wherein a cross-linking agent is further mixed in the polysulfide rubber, the cross-linking agent is at least one of a metal oxide, a peroxide and an oxidizing agent, and the mass of the cross-linking agent is 0.5-5% of that of the polysulfide rubber.

5. The method for preparing a composite diaphragm of a loudspeaker according to claim 2, wherein the polysulfide rubber is further mixed with a filler, and the filler is at least one of a carbon material, silicon oxide, silicate, carbonate, sulfate and metal oxide; the filler accounts for 0.1-50% of the mass of the polysulfide rubber.

6. The method for preparing a composite diaphragm of a loudspeaker according to claim 1, wherein the polysulfide rubber layer has a hardness of 20 to 85A, a loss factor of 0.1 to 1 at room temperature, and a storage modulus of 1 to 15MPa at room temperature.

7. The method of claim 1, wherein the thermoplastic elastomer layer is made of at least one thermoplastic elastomer selected from the group consisting of styrene-based thermoplastic elastomers, olefin-based thermoplastic elastomers, diene-based thermoplastic elastomers, vinyl chloride-based thermoplastic elastomers, urethane-based thermoplastic elastomers, ester-based thermoplastic elastomers, amide-based thermoplastic elastomers, organic fluorine-based thermoplastic elastomers, silicone-based thermoplastic elastomers, and ethylene-based thermoplastic elastomers.

8. The method for preparing a composite diaphragm of a loudspeaker according to claim 1, wherein the method for preparing the polysulfide 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.

9. The method of claim 1, wherein the polysulfide rubber layer and the thermoplastic elastomer layer are laminated together by thermal bonding, or the polysulfide rubber layer is directly coated on the surface of the thermoplastic elastomer layer, and then dried and laminated together to form the composite membrane.

10. The method of claim 1, wherein the molding process is air pressure molding or compression molding.

11. A composite diaphragm for a speaker, characterized in that it is produced by the production method of any one of claims 1 to 10.

12. A loudspeaker comprising a composite diaphragm as claimed in claim 11.