JP6394662B2 - Diaphragm edge material for electroacoustic transducer, diaphragm for electroacoustic transducer, and microspeaker diaphragm - Google Patents

Description

  The present invention relates to a diaphragm edge material for an electroacoustic transducer used for various acoustic devices, and more particularly, suitable as a speaker diaphragm, heat resistance, durability at high output, reproduction from low to high sounds. In particular, the present invention relates to a diaphragm for an electroacoustic transducer that has excellent properties and secondary workability.

  With the spread of small electronic devices (for example, mobile phones, PDAs, notebook computers, DVDs, liquid crystal TVs, digital cameras, portable music devices, etc.), small speakers (usually called micro speakers) used in these electronic devices. In addition, there is an increasing demand for small electroacoustic transducers such as microphones and earphones.

  In general, the speaker diaphragm has a low density to maintain the sound radiation sound pressure level, a high rigidity to suppress distortion and maintain a large allowable input, and a tension to widen the reproduction frequency band. It is required that the elastic modulus is in a specific range and that the internal loss is large in order to suppress the divided vibration of the diaphragm and flatten the frequency characteristics. In addition, when used in the vicinity of a voice coil that is the driving source of a speaker or a vehicle-mounted speaker, the diaphragm is exposed to a high temperature for a long time. It becomes.

  On the other hand, in recent years, with the background of mobile society, ubiquitous society, and digitization of music sources, various small electronic devices have been improved in function and performance. Also in the speakers used for these, for example, the input / output resistance level required for the speaker diaphragm of a mobile phone is about 0.3 W for general-purpose models, and 0.5 to 0.6 W for high-output models. More than about (the upper limit at present is about 1.2 W) has been improved. However, at present, there are many models of about 0.6 to 0.8 W, and the ratio of models exceeding 1.0 W is low.

  For such problems, Patent Document 1 discloses a diaphragm formed by molding a polyimide resin film, and the member has toughness, dimensional stability, corrosion resistance, heat and cold resistance, weather resistance, There is a description that it is excellent in properties such as strength. However, the polyimide resin used for the member has a drawback that it is thermosetting and is inferior in film productivity. Moreover, since the thermosetting polyimide resin has an elastic modulus that is too high, it has a drawback that it is not suitable for low-pitched sound reproduction.

  Patent Document 2 discloses a speaker diaphragm formed by molding a polyetherimide resin, and describes that the member is excellent in heat resistance, internal loss, and rigidity. Polyetherimide resin is thermoplastic, so it has excellent film productivity, which is a drawback of the thermosetting polyimide resin. It also has a high glass transition temperature and excellent heat resistance, but it also has a high elastic modulus. Too low for bass playback.

JP-A 51-006014 JP 60-055797 A

  The present invention relates to an edge material that can be used for a diaphragm for an electroacoustic transducer having excellent heat resistance, durability at high output, reproducibility from low to high sounds, and secondary workability, and the edge material It aims at providing the diaphragm for electroacoustic transducers which used the.

  As a result of intensive studies, the present inventor has found that the above problems can be solved by using a crystalline polyimide resin having a specific structure, and has reached the present invention.

  That is, the first aspect of the present invention is based on a crystalline polyimide resin (A) comprising a tetracarboxylic acid component (a-1) and a diamine component (a-2) containing an aliphatic diamine as a main component. It is the diaphragm edge material for electroacoustic transducers to contain.

  1st aspect of this invention WHEREIN: It is preferable that the said diamine component (a-2) contains a C4-C12 linear aliphatic diamine at least.

  1st aspect of this invention WHEREIN: It is preferable that the said diamine component (a-2) contains an alicyclic diamine at least.

  In the first aspect of the present invention, the alicyclic diamine is preferably 1,3-bis (aminomethyl) cyclohexane.

  The diaphragm edge material for an electroacoustic transducer according to the first aspect of the present invention is preferably made of a film having a tensile modulus of elasticity of 1000 MPa or more and less than 2500 MPa in accordance with JIS K7127.

  The diaphragm edge material for an electroacoustic transducer according to the first aspect of the present invention is preferably made of a film having a folding strength of 1000 times or more according to JIS P8115.

  The diaphragm edge material for an electroacoustic transducer according to the first aspect of the present invention is preferably made of a film having a tensile elongation at breakage of 200% or more according to JIS K7127.

  The diaphragm edge material for an electroacoustic transducer according to the first aspect of the present invention preferably has a crystal melting enthalpy (ΔHm) of 25 J / g or more.

  The diaphragm edge material for an electroacoustic transducer according to the first aspect of the present invention is preferably made of a film having a thickness of 1 μm or more and 200 μm or less.

  The diaphragm edge material for an electroacoustic transducer according to the first aspect of the present invention includes an acrylic adhesive, a rubber-based adhesive, a silicone-based adhesive, and a urethane-based adhesive plate for the electroacoustic transducer. At least one pressure-sensitive adhesive layer selected from pressure-sensitive adhesives may be disposed in the intermediate layer.

  A second aspect of the present invention is an electroacoustic transducer diaphragm using the electroacoustic transducer diaphragm edge material according to the first aspect of the present invention.

A third aspect of the present invention is a micro speaker diaphragm using the diaphragm edge material for an electroacoustic transducer according to the first aspect of the present invention.

  According to the present invention, the vibration for an electroacoustic transducer is excellent in heat resistance, durability at high output, reproducibility from low to high sounds, and secondary workability, and can be suitably used when used in various acoustic devices. A plate edge material and an electroacoustic transducer diaphragm using the edge material can be provided.

It is sectional drawing which shows the structure of the micro speaker diaphragm 1 which concerns on one Embodiment of this invention. It is a top view of micro speaker diaphragm 1 'concerning other embodiments of the present invention.

  Hereinafter, the present invention will be described in detail, but the present invention is not limited to the embodiments described below. Unless otherwise specified, the notation “A to B” for numerical values A and B means “A to B”. In this notation, when a unit is attached to only the numerical value B, the unit is also applied to the numerical value A.

  The diaphragm edge material for electroacoustic transducers of the present invention contains a crystalline polyimide resin (A) as a main component. Here, “main component” means that the proportion of the crystalline polyimide resin (A) contained in the diaphragm edge material for an electroacoustic transducer exceeds 50 mass%. The proportion of the crystalline polyimide resin (A) contained in the diaphragm edge material for an electroacoustic transducer is important to exceed 50% by mass, preferably 60% by mass or more, and 70% by mass or more. More preferably, it is more preferably 80% by mass or more, particularly preferably 90% by mass or more, and especially all of the components (100% by mass) constituting the diaphragm edge material for electroacoustic transducers are crystalline polyimide. The resin (A) is particularly preferable.

[Crystalline polyimide resin (A)]
The crystalline polyimide resin (A) used in the present invention is obtained by polymerizing a tetracarboxylic acid component and a diamine component.

  The tetracarboxylic acid component (a-1) constituting the crystalline polyimide resin (A) is cyclobutane-1,2,3,4-tetracarboxylic acid, cyclopentane-1,2,3,4-tetracarboxylic acid, Cycloaliphatic tetracarboxylic acid such as cyclohexane-1,2,4,5-tetracarboxylic acid, 3,3 ′, 4,4′-diphenylsulfonetetracarboxylic acid, 3,3 ′, 4,4′-benzophenone tetra Examples thereof include carboxylic acid, biphenyltetracarboxylic acid, naphthalene-1,4,5,8-tetracarboxylic acid, pyromellitic acid and the like. Moreover, these alkyl ester bodies can also be used.

  Especially, it is preferable that the component exceeding 50 mol% among tetracarboxylic acid components (a-1) is pyromellitic acid. When the tetracarboxylic acid component (a-1) contains pyromellitic acid as a main component, the diaphragm edge material for an electroacoustic transducer of the present invention is excellent in heat resistance, secondary workability, and low water absorption. From this viewpoint, among the tetracarboxylic acid component (a-1), pyromellitic acid is more preferably 60 mol% or more, further preferably 80 mol% or more, and 90 mol% or more. In particular, it is particularly preferable that all (100 mol%) of the tetracarboxylic acid component (a-1) is pyromellitic acid.

  It is important that the diamine component (a-2) constituting the crystalline polyimide resin (A) is mainly composed of an aliphatic diamine. That is, it is important that the component exceeding 50 mol% of the diamine component (a-2) is an aliphatic diamine, more preferably 60 mol% or more, and still more preferably 80 mol% or more. 90 mol% or more is particularly preferable, and it is particularly preferable that all (100 mol%) of the diamine component (a-2) is an aliphatic diamine. Thereby, heat resistance, low water absorption, moldability, and secondary workability can be imparted to the diaphragm for electroacoustic transducers of the present invention. The aliphatic diamine in the present invention includes alicyclic diamines.

  The aliphatic diamine contained in the diamine component (a-2) is not particularly limited as long as it is a diamine component having amine groups at both ends of the hydrocarbon group. It is preferable to include an alicyclic diamine having an amine group at the terminal of the amount of hydrogen. Specific examples of the alicyclic diamine include 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, 4,4′-diaminodicyclohexylmethane, 4,4′-methylenebis (2- Methylcyclohexylamine), isophoronediamine, norbornanediamine, bis (aminomethyl) tricyclodecane and the like. Among these, 1,3-bis (aminomethyl) cyclohexane is preferably used from the viewpoint of achieving both heat resistance, moldability, and secondary processability.

  On the other hand, in the diaphragm for electroacoustic transducers of the present invention, when emphasizing moldability and secondary processability, the amount of linear hydrocarbon as the aliphatic diamine contained in the diamine component (a-2) It preferably contains a linear aliphatic diamine having an amine group at the terminal. The linear aliphatic diamine is not particularly limited as long as it is a diamine component having amine groups at both ends of the alkyl group. Specific examples include ethylene diamine (carbon number 2), propylene diamine (carbon number 3), Butanediamine (carbon number 4), pentanediamine (carbon number 5), hexanediamine (carbon number 6), heptanediamine (carbon number 7), octanediamine (carbon number 8), nonanediamine (carbon number 9), decanediamine ( 10 carbon atoms, undecane diamine (11 carbon atoms), dodecane diamine (12 carbon atoms), tridecane diamine (13 carbon atoms), tetradecane diamine (14 carbon atoms), pentadecane diamine (15 carbon atoms), hexadecane diamine (carbon) 16), heptadecanediamine (carbon number 17), octadecanediamine (carbon number 18) Nona decane diamine (19 carbon atoms), eicosane (20 carbon atoms), triacontane (30 carbon atoms), Tetorakontan (40 carbon atoms), pentacontanoic (number 50 atoms) and the like. Among these, C4-C12 linear aliphatic diamine is mentioned from a viewpoint that it is excellent in a moldability, secondary workability, and low hygroscopicity. These linear aliphatic diamines may have a branched structure having 1 to 10 carbon atoms.

  As a component other than the aliphatic diamine contained in the diamine component (a-2), another diamine component may be included. Specifically, 1,4-phenylenediamine, 1,3-phenylenediamine, 2,4-toluenediamine, 4,4′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 4,4′-diaminodiphenylmethane, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, α, α'-bis (4-aminophenyl) ) 1,4′-diisopropylbenzene, α, α′-bis (3-aminophenyl) -1,4-diisopropylbenzene, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 4,4 '-Diaminodiphenylsulfone, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) Enyl] sulfone, 2,6-diaminonaphthalene, 1,5-diaminonaphthalene, aromatic diamine components such as p-xylylenediamine, m-xylylenediamine, polyethylene glycol bis (3-aminopropyl) ether, polypropylene glycol bis Examples include ether diamine components such as (3-aminopropyl) ether, siloxane diamines, and the like.

  The diamine component (a-2) may contain either or both of an alicyclic diamine and a linear aliphatic diamine, but since it has an excellent balance between heat resistance and moldability, It is preferable to contain both chain aliphatic diamines. When both an alicyclic diamine and a linear aliphatic diamine are included, the content of each is preferably in the range of alicyclic diamine: linear aliphatic diamine = 99: 1 to 1:99 mol%. 90:10 to 10:90 mol%, more preferably 80:20 to 20:80 mol%, still more preferably 70:30 to 30:70 mol%, 60 : 40 to 40: 60 mol% is particularly preferable. If the ratio of the alicyclic diamine and the linear aliphatic diamine contained in the diamine component (a-2) is within such a range, the diaphragm edge material for an electroacoustic transducer of the present invention has a balance between heat resistance and moldability. Excellent.

  The crystal melting temperature of the crystalline polyimide resin (A) is preferably 260 ° C. or higher and 340 ° C. or lower, more preferably 270 ° C. or higher and 335 ° C. or lower, and 280 ° C. or higher and 330 ° C. or lower. Further preferred. When the crystalline melting temperature of the crystalline polyimide resin (A) is 260 ° C. or higher, the heat resistance of the diaphragm edge material for electroacoustic transducers is sufficient. For example, the heat resistance which can endure the reflow process whose peak temperature is 260 degreeC can be provided. On the other hand, if the crystal melting temperature is 340 ° C. or lower, for example, it is possible to perform secondary processing at a relatively low temperature using a general-purpose facility in the melt molding of a film used for the diaphragm edge material for an electroacoustic transducer of the present invention. preferable.

[Diaphragm edge material for electroacoustic transducers]
The diaphragm edge material for an electroacoustic transducer according to the present invention can be applied to any material used for an electroacoustic transducer such as a speaker, a receiver, a microphone, an earphone or the like, and particularly as a microspeaker diaphragm for a mobile phone or the like. It can be used suitably.

  The glass transition temperature (Tg) of the diaphragm edge material for an electroacoustic transducer is preferably 150 ° C. or higher, more preferably 160 ° C. or higher, and further preferably 170 ° C. or higher. If the glass transition temperature of the diaphragm edge material for an electroacoustic transducer is 150 ° C. or higher, sufficient heat resistance can be maintained.

  The crystal melting enthalpy (ΔHm) of the diaphragm edge material for an electroacoustic transducer is preferably 25 J / g or more, more preferably 30 J / g or more, and further preferably 35 J / g or more. If the crystal melting enthalpy (ΔHm) is 25 J / g or more, a highly crystalline film or molded product can be obtained, and the electroacoustic transducer diaphragm not only has excellent heat resistance, but can also ensure high-frequency reproducibility. It is preferable because an elastic modulus of 2 is obtained.

  The crystal melting temperature of the diaphragm edge material for an electroacoustic transducer is preferably 260 ° C or higher and 340 ° C or lower, more preferably 270 ° C or higher and 335 ° C or lower, and 280 ° C or higher and 330 ° C or lower. Further preferred. If the crystal melting temperature of the diaphragm edge material for an electroacoustic transducer is 260 ° C. or higher, sufficient heat resistance can be imparted. On the other hand, if the crystal melting temperature of the diaphragm edge material for an electroacoustic transducer is 340 ° C. or lower, the moldability during melt molding is excellent.

  In addition, the diaphragm edge material for electroacoustic transducers of this invention can be obtained by carrying out the secondary process of the film provided with the preferable characteristic shown below by the method mentioned later.

  The film used for the diaphragm edge material for an electroacoustic transducer of the present invention preferably has a tensile modulus of elasticity of 1000 MPa or more and less than 2500 MPa in accordance with JIS K7127. If the tensile modulus is 1000 MPa or more, reproducibility in a high temperature range is ensured, and it has sufficient rigidity as a diaphragm edge material for an electroacoustic transducer. From this viewpoint, the tensile elastic modulus is more preferably 1500 MPa or more, and particularly preferably 1800 MPa or more. On the other hand, if the tensile elastic modulus is less than 2500 MPa, for example, in the case of a diaphragm of a micro speaker, the minimum resonance frequency (f0) can be obtained even if a film having a thickness of 20 to 40 μm excellent in handling property and durability at high output is used. : F-zero) is sufficiently low, low-frequency reproduction is ensured, and sound quality is good, which is preferable. From this viewpoint, the tensile elastic modulus is more preferably 2400 MPa or less, and particularly preferably 2300 MPa or less.

  The film used for the diaphragm edge material for an electroacoustic transducer of the present invention preferably has a folding endurance of 1000 times or more, more preferably 1500 times or more according to JIS P8115. If the bending strength is within the range, durability at high output is excellent, and the diaphragm is less likely to crack or break.

  The film used for the diaphragm edge material for an electroacoustic transducer of the present invention preferably has a tensile elongation at breakage of 200% or more, more preferably 250% or more in accordance with JIS K7127. As long as the tensile elongation at break is within the range, troubles such as breakage can be prevented and secondary processing can be stably performed even in various shapes, for example, shapes requiring deep drawability.

  Further, the film used for the diaphragm edge material for electroacoustic transducers of the present invention includes other resins, fillers, various additives, for example, heat, in the range not exceeding the gist of the present invention, in addition to the components described above. Stabilizers, ultraviolet absorbers, light stabilizers, nucleating agents, colorants, lubricants, flame retardants and the like may be appropriately blended.

  As a method for forming a film used in the diaphragm edge material for an electroacoustic transducer of the present invention, a known method such as an extrusion casting method using a T-die, a calendar method, or a casting method can be employed. Although not particularly limited, an extrusion casting method using a T die is preferably used from the viewpoint of film productivity and the like. The molding temperature in the extrusion casting method using a T-die is appropriately adjusted depending on the flow characteristics and film forming properties of the composition used, but is generally 280 ° C. or higher and 350 ° C. or lower. For melt-kneading, generally used single-screw extruders, twin-screw extruders, kneaders, mixers, and the like can be used, and are not particularly limited.

  In the case of the extrusion casting method using a T-die, the obtained film may be rapidly cooled and collected in an amorphous state, or may be crystallized by heating with a casting roll, or after being collected in an amorphous state. You may extract | collect in the state which gave the heat processing and crystallized. In general, amorphous films are excellent in durability and secondary processability, and films after crystallization are excellent in heat resistance and rigidity (koshi). is important.

  When using a crystallized film, it is preferable to crystallize by heating with a casting roll from the viewpoint of productivity and cost. In general, when a thin film is collected by crystallization with a casting roll, it is necessary to increase the line speed, and since the time for the film to contact the casting roll is short, the crystallization is not completed sufficiently, and the desired crystallinity is obtained. There is a case where a film having the above cannot be obtained. Since the crystalline polyimide resin (A) used in the present invention has a very high crystallization rate, a thin film having sufficient crystallinity can be obtained by heat treatment with a casting roll.

  As a standard for making the crystallization rate preferable, the crystalline polyimide resin (A) is heated to a temperature equal to or higher than the crystal melting temperature using a differential scanning calorimeter (DSC) at a heating rate of 10 ° C./min. When the temperature of the crystallization peak when the temperature is lowered at 10 ° C./min after the crystal is melted is defined as the temperature-lowering crystallization temperature, the difference between the crystal melting temperature and the temperature-lowering crystallization temperature is preferably 70 ° C. or less. The temperature is preferably 60 ° C. or lower, and more preferably 50 ° C. or lower. If the crystallization peak in the temperature lowering process is within such a temperature range, the crystallization speed is sufficiently high, and a thin film having sufficient crystallinity can be obtained by heat treatment with a casting roll.

  Although the thickness of the film used for the diaphragm edge material for electroacoustic transducers of the present invention is not particularly limited, it is usually 1 to 200 μm as the diaphragm edge material for electroacoustic transducers. It is also important to form a film so that the anisotropy of the physical properties in the flow direction (MD) from the film extruder (MD) and its orthogonal direction (TD) is as small as possible.

  The film thus obtained is further subjected to secondary processing as a diaphragm edge material for an electroacoustic transducer. The secondary processing method is not particularly limited. For example, in the case of a speaker diaphragm, the film is heated in consideration of its glass transition temperature and softening temperature, and the dome shape or the like is formed by press molding or vacuum molding. Secondary processed into a cone shape. Moreover, the shape of the diaphragm is not particularly limited, and is arbitrary, and a circular shape, an elliptical shape, an oval shape, or the like can be selected. FIG. 1 is a diagram showing the structure of a micro speaker diaphragm 1 according to an embodiment of the present invention, which is a cross-sectional view of a circular micro speaker diaphragm 1 cut in a plane passing through the center line of a circle in plan view. is there. As shown in FIG. 1, the microspeaker diaphragm 1 has a dome (body) 1a as a center, a recessed fitting portion 1b attached to the voice coil 2, a peripheral edge (edge) 1c, and a frame or the like attached to the outer periphery thereof. It has the external sticking part 1d to attach.

  Since the film used for the diaphragm edge material for electroacoustic transducers of the present invention has a tensile modulus that is not too high, the reproducibility in the low range is ensured particularly when used for a diaphragm edge material for small electroacoustic transducers. This is preferable because the sound quality is improved. Here, as the size of the diaphragm, those having a maximum diameter of 25 mm or less, preferably 20 mm or less, and a lower limit of usually about 5 mm are suitably used. The maximum diameter is a diameter when the diaphragm is circular, and a long diameter when the diaphragm is elliptical or oval.

  A groove having a V-shaped cross section called a so-called tangential edge can be appropriately provided on the diaphragm surface. FIG. 2 is a plan view of a micro speaker diaphragm 1 ′ according to another embodiment of the present invention. The micro speaker diaphragm 1 ′ is provided with a tangential edge portion 1g provided with a plurality of tangential edges 1e and a plurality of tangential edges 1f on an outer peripheral edge portion of a circular dome portion (body) 1a ′. A tangential edge portion 1h. In the form having a tangential edge, the average thickness of the film is preferably 3 to 40 μm, more preferably 5 to 38 μm, since the thickness is sufficiently secured, the handling property is good, and the time per unit such as press molding is good. This is preferable because secondary workability and secondary work accuracy (shape reproducibility) are easily improved.

  Further, the diaphragm edge material for an electroacoustic transducer of the present invention may be a laminate having the diaphragm edge material for an electroacoustic transducer in front and back layers and an adhesive layer having a high damping effect (internal loss) in an intermediate layer. Good. By adopting such a laminated structure, in addition to the heat resistance, rigidity, durability, and moldability of the diaphragm edge material for electroacoustic transducers in the front and back layers, it is possible to impart excellent damping characteristics possessed by the intermediate layer. . The method for producing a diaphragm edge material for an electroacoustic transducer that is a laminate is not particularly limited. For example, a pair of films having the above-mentioned preferable characteristics are secondarily processed to produce diaphragm edges for electroacoustic transducers constituting a surface layer and a back layer, and these are bonded via an adhesive used for an intermediate layer Or a method of producing a laminated film by adhering a pair of films having the above-mentioned preferable properties via an adhesive used for an intermediate layer, and then subjecting the laminated film to secondary processing by the above method, etc. Can be mentioned. In this case, examples of the pressure-sensitive adhesive used for the intermediate layer include acrylic pressure-sensitive adhesives, rubber pressure-sensitive adhesives, silicone-based pressure-sensitive adhesives, urethane-based pressure-sensitive adhesives and the like. It is preferable to use a system adhesive. In this case, the thickness of the surface layer and the back layer is preferably 1 μm or more and 30 μm or less, more preferably 2 μm or more and 25 μm or less, and further preferably 3 μm or more and 20 μm or less. On the other hand, the intermediate layer thickness is preferably 3 μm or more and 50 μm or less, more preferably 5 μm or more and 40 μm or less, and further preferably 10 μm or more and 30 μm or less. When the material type of the intermediate layer and the thickness of each layer are applied, a diaphragm having excellent damping characteristics while maintaining various mechanical characteristics and molding can be obtained.

  Furthermore, for the secondary processing suitability and dustproof of the diaphragm, the adjustment of the acoustic characteristics and the improvement of the design, etc., the film used for the diaphragm edge material for the electroacoustic transducer of the present invention or the surface of the molded diaphragm Coating or laminating antistatic agents and various elastomers (for example, urethane, silicone, hydrocarbon, fluorine, etc.), depositing metal, sputtering or coloring (black, white, etc.) These processes may be performed as appropriate. Furthermore, lamination with a metal such as aluminum or another film, or combination with a non-woven fabric may be performed as appropriate.

  The diaphragm edge material for an electroacoustic transducer of the present invention is excellent in durability at high output when used for a speaker diaphragm. For example, in a mobile phone, it is possible to cope with an output withstand level of about 0.6 to 1.0 W applicable to a high output model, as compared to about 0.3 W of a general-purpose model. Films containing crystalline polyimide resin (A) as a main component are not only the basic acoustic properties of speaker diaphragms, especially microspeaker diaphragms, but also heat resistance and molding during diaphragm secondary processing. Also excellent in properties.

  In general, "film" is a thin flat product whose thickness is extremely small compared to the length and width and whose maximum thickness is arbitrarily limited, and is usually supplied in the form of a roll. (JIS K6900) In general, the term “sheet” refers to a product that is thin according to the definition in JIS, and whose thickness is small for the length and width but flat. However, since the boundary between the sheet and the film is not clear and it is not necessary to distinguish the two in terms of the present invention, in the present invention, even when the term “film” is used, the term “sheet” is included and the term “sheet” is used. In some cases, “film” is included.

  Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto. In addition, the various measurement about the film used for the raw material described in this specification and the diaphragm edge material for electroacoustic transducers of this invention was performed as follows.

(1) Glass transition temperature, crystal melting temperature, crystal melting enthalpy, crystallization temperature at the time of temperature reduction Various raw materials and the obtained film were measured by a differential scanning calorimeter (DSC) measurement at a heating rate of 10 ° C./min according to JIS K7121. The glass transition temperature, crystal melting temperature, and crystal melting enthalpy in the temperature rising process were measured. Then, about the crystalline material, the temperature of the crystallization peak (temperature-falling crystallization temperature) at the time of temperature-falling at 10 degreeC / min was measured, and the crystallization speed was evaluated from the difference with crystal melting temperature.

(2) Tensile modulus The obtained film was measured under the condition of a temperature of 23 ° C. according to JIS K7127.

(3) Folding strength The obtained film was measured in accordance with JIS P8115 at a temperature of 23 ° C.

(4) Tensile elongation at break The obtained film was measured in accordance with JIS K7127 under conditions of a temperature of 23 ° C. and a test speed of 200 mm / min.

1. Crystalline polyimide resin (A)
(A) -1: crystalline polyimide resin (Mitsubishi Gas Chemical Co., Ltd., trade name: Surprim TO65S, tetracarboxylic acid component: pyromellitic acid = 100 mol%, diamine component: 1,3-bis (aminomethyl) cyclohexane / Octamethylenediamine = 60/40 mol%, crystal melting temperature: 322 ° C., crystal melting enthalpy: 40 J / g, glass transition temperature: 185 ° C.)

Example 1
(A) -1 as a crystalline polyimide resin (A) is melt-kneaded at 340 ° C. using a Φ40 mm single-screw extruder, then extruded from a T die, and then heated and crystallized with a casting roll at about 200 ° C., A crystallized film having a thickness of 25 μm was prepared. The obtained films (1) to (4) were measured. The results are shown in Table 1.

(Comparative Example 1)
Instead of the crystalline polyimide resin (A), (N) -1: polyetherimide 1000 (SABIC Innovative Plastics Co., Ltd., Ultem 1000, amorphous resin, glass transition temperature: 220 ° C.) is used, and the molding temperature is changed. A film was prepared and measured in the same manner as in Example 1 except that the temperature was 380 ° C. The results are shown in Table 1.

(Comparative Example 2)
Instead of the crystalline polyimide resin (A), (N) -2: polyetherimide 5000 (manufactured by SABIC Innovative Plastics, Ultem CRS 5001, amorphous resin, glass transition temperature: 230 ° C.) is used, and the molding temperature is changed. A film was prepared and measured in the same manner as in Example 1 except that the temperature was 380 ° C. The results are shown in Table 1.

(Comparative Example 3)
(N) -3: crystalline polyimide resin (Mitsui Chemicals, trade name: Aurum PL450C, tetracarboxylic acid component: pyromellitic acid = 100 mol%, diamine component: 4 instead of crystalline polyimide resin (A) , 4′-bis (3-aminophenoxy) biphenyl = 100 mol%, crystal melting temperature: 387 ° C., crystal melting enthalpy: 34 J / g, glass transition temperature: 245 ° C.), casting temperature 400 ° C., casting A film was prepared and measured in the same manner as in Example 1 except that the roll temperature was 230 ° C. and an amorphous film was collected. The results are shown in Table 1.

  In Example 1, a film mainly composed of the crystalline polyimide resin (A) of the present invention is used in a crystallized state. Since the film has a tensile elastic modulus in an appropriate range, it has not only excellent rigidity and handling properties but also excellent low-frequency reproduction. Further, since the toughness of the crystallized film usually decreases, the value of the bending strength and the tensile elongation at break tends to decrease. However, even if the film is in a crystallized state, these items are sufficient. Excellent value, and as a result, excellent durability at high output. Further, since the crystal melting enthalpy, the crystal melting temperature, the bending strength, and the tensile elongation at break are within preferable ranges, the heat resistance, durability at high output, and secondary workability are excellent. Furthermore, since the difference between the crystal melting temperature and the crystallization temperature at the time of temperature drop is small, the crystallization speed is sufficiently high, and a 25 μm film having sufficient crystallinity is obtained by heat treatment with a casting roll.

  On the other hand, in Comparative Examples 1 and 2, a film made of polyetherimide, which is a heat-resistant amorphous resin, is used. Since the film uses an amorphous resin, it does not have a melting point and is inferior in heat resistance. In addition, the tensile modulus is high and the reproducibility of the bass is inferior, and the bending strength and tensile elongation at break are low, so that the durability and secondary workability at high output are not sufficient.

  In Comparative Example 3, a film made of a crystalline polyimide resin containing pyromellitic acid and 4,4′-bis (3-aminophenoxy) biphenyl as main components is used. The obtained amorphous film does not reach a level sufficient for mechanical properties such as elastic modulus, bending strength, and tensile elongation at break to be used as a diaphragm. In addition, since the raw material has a large difference between the crystal melting temperature and the crystallization temperature when the temperature is lowered (crystallization speed is low), a crystallized film is not obtained by heat treatment with a casting roll, but a crystallized film is obtained. In general, the elastic modulus is improved by crystallizing the film, and the bending strength and tensile elongation at break tend to be lowered. Therefore, physical properties suitable for use as a diaphragm cannot be obtained. Is obvious. Furthermore, since the raw material has a very high melting point, it is necessary to set the temperature of the molding machine to 400 ° C. or higher in order to obtain sufficient fluidity during film formation, which is not only disadvantageous in terms of energy, but also the discharge amount. The productivity is inferior because there are few.

1, 1 'speaker diaphragm 1a, 1a' dome part (body)
1b Recessed part 1c Peripheral part (edge)
1d External pasting part 1e, 1f Tangential edge 1g, 1h Tangential edge part 2 Voice coil

Claims (12)

  Diaphragm edge material for electroacoustic transducers containing as a main component a crystalline polyimide resin (A) comprising a tetracarboxylic acid component (a-1) and a diamine component (a-2) containing an aliphatic diamine as a main component. .   The diaphragm edge material for electroacoustic transducers according to claim 1, wherein the diamine component (a-2) contains at least a linear aliphatic diamine having 4 to 12 carbon atoms.   The diaphragm edge material for an electroacoustic transducer according to claim 1 or 2, wherein the diamine component (a-2) contains at least an alicyclic diamine.   4. The diaphragm edge material for an electroacoustic transducer according to claim 3, wherein the alicyclic diamine is 1,3-bis (aminomethyl) cyclohexane. The diaphragm edge material for an electroacoustic transducer according to any one of claims 1 to 4 , wherein the diaphragm elastic material comprises a film having a tensile modulus of elasticity of 1000 MPa or more and less than 2500 MPa in accordance with JIS K7127.   The diaphragm edge material for electroacoustic transducers according to any one of claims 1 to 5, characterized in that it comprises a film having a bending strength of 1000 times or more in accordance with JIS P8115.   The diaphragm edge material for an electroacoustic transducer according to any one of claims 1 to 6, wherein the diaphragm edge material is made of a film having a tensile elongation at breakage of 200% or more in accordance with JIS K7127.   The diaphragm edge material for an electroacoustic transducer according to any one of claims 1 to 7, wherein the crystal melting enthalpy (ΔHm) is 25 J / g or more.   The diaphragm edge material for an electroacoustic transducer according to any one of claims 1 to 8, wherein the diaphragm edge material comprises a film having a thickness of 1 µm or more and 200 µm or less.   The diaphragm edge material for an electroacoustic transducer according to any one of claims 1 to 9, wherein the front and back layers are at least one selected from an acrylic adhesive, a rubber adhesive, a silicone adhesive, and a urethane adhesive. A diaphragm edge material for an electroacoustic transducer, characterized in that a pressure-sensitive adhesive layer is disposed on an intermediate layer.   The diaphragm for electroacoustic transducers using the diaphragm edge material for electroacoustic transducers of any one of Claims 1-10. The micro speaker diaphragm using the diaphragm edge material for electroacoustic transducers of any one of Claims 1-10.

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