JP6628783B2 - Method for manufacturing film for speaker diaphragm - Google Patents

Description

  The present invention relates to a method for manufacturing a film for a diaphragm of a speaker having excellent heat resistance and sound quality characteristics.

  2. Description of the Related Art A small speaker called a micro speaker is built in a portable device such as a mobile phone, a portable game device, and a smartphone. A diaphragm for generating sound waves of a speaker called a micro speaker generally includes (1) metal foil, (2) paper, woven fabric, nonwoven fabric made of natural resin, or (3) resin film made of synthetic resin. It is an important part that determines the sound quality.

  In the case where the diaphragm is not (1) or (2) but a synthetic resin resin film of (3), a polyolefin resin such as polyethylene (PE) resin or polypropylene (PP) resin, polyethylene terephthalate has been used. Resin films made of (PET) resin, polyester resin such as polyethylene naphthalate (PEN) resin, polyphenylene sulfide (PPS) resin, polyetherimide (PEI) resin and the like are used (see Patent Documents 1 and 2). .

  By the way, in recent years, loudspeakers have been increasingly improved in function and performance. Therefore, the required characteristics of the speaker diaphragm are becoming more and more severe. The required characteristics of the diaphragm include light weight (low density or specific gravity), moderate rigidity (Young's modulus and elastic modulus), excellent thickness accuracy, loss tangent (both internal loss and , Tan δ) and excellent heat resistance. In addition, it also has excellent moisture resistance, water resistance, and moldability (press molding, vacuum molding, pressure molding, etc.).

However, when the diaphragm of the speaker is the metal foil of (1), although the heat resistance and the water resistance are excellent, the rigidity is large, so the minimum resonance frequency (f ₀ ) is high, and the bass reproduction characteristics are insufficient. . Further, since the important loss tangent (also referred to as internal loss, also referred to as tan δ) for the diaphragm is small, the diaphragm resonates, the acoustic characteristics are disturbed, high performance cannot be expected, and a problem occurs in sound quality. . Further, since the density is high, the vibration propagation speed becomes slow and the reproduction frequency band becomes narrow, which causes a problem in acoustic characteristics.

  In the case where the diaphragm of the speaker is made of natural resin paper, woven fabric or non-woven fabric of (2), although the density is low and the weight is low, the rigidity is low, so that a problem occurs in reproduction in a high frequency region, and it is important. Since the loss tangent is also small, the sound quality still has a problem. In addition, it becomes difficult to obtain sufficient moisture resistance, water resistance, and heat resistance, and the manufacturing process of the speaker becomes complicated.

  On the other hand, when the diaphragm of the speaker is a resin film made of a synthetic resin of (3), a change in the material of the synthetic resin allows selection of a loss tangent, etc. Since it is suitable for thinning, weight reduction, and mass production, it is most suitable for incorporating small and lightweight portable devices. In view of these points, a diaphragm made of a synthetic resin resin film is used for a speaker built in a portable device in recent years.

  By the way, recently, due to a change in lifestyle associated with the sophistication of mobile devices, many users want to enjoy television programs, music, games, and the like on mobile devices regardless of time and place. Specifically, a single portable device can be used in public transportation when commuting, beaches and ski resorts where the temperature changes drastically, recreational facilities during noisy vacations, running while swinging up, down, back and forth, and left and right. There are many users who want to enjoy TV programs, music, games, etc., and use their time effectively to enrich their lives.

  In order to meet the needs of such users, the performance of the speaker should be taken into account, taking into account the special circumstances that the speaker is not built into stationary audio equipment used in a stable environment but is built into portable equipment. It is necessary to improve or increase the output. Specifically, on the premise that the portable device is used for a long time in an unfavorable use environment or the external output is increased and the loud volume is used for a long time, the heat resistance of the speaker diaphragm is further improved, There is a need to improve speaker durability.

Since the synthetic resin resin film has insufficient heat resistance, when used as a diaphragm for a speaker, if the external output is increased, high heat generated by high vibration of the voice coil causes deformation of the diaphragm, or There is a problem in durability such as damage.
In recent years, a resin film made of polyetheretherketone (PEEK) resin has been proposed and used as a diaphragm film for a speaker (see Patent Document 3).

JP-A-60-139098 JP-A-64-067099 JP-A-58-222699

  The resin film made of polyetheretherketone resin has a glass transition point of 150 ° C. or more and less than 160 ° C. (measurement method: dynamic viscoelasticity method) and a melting point of 330 ° C. or more and 350 ° C. or less (measurement method: differential scanning calorimetry) Method) and excellent heat resistance.

  However, it is said that a speaker of a portable device with high functionality and high output generates heat due to high vibration of a voice coil at the time of output, and the temperature of the diaphragm reaches about 160 ° C. Since the resin film made of polyetheretherketone resin has a glass transition temperature of about 150 ° C., when used for a diaphragm of a speaker of a portable device, the diaphragm is deformed due to high heat accompanying high vibration of a voice coil, Or it may be damaged.

  The present invention has been made in view of the above, and an object of the present invention is to provide a method for manufacturing a film for a speaker diaphragm, which can ensure heat resistance of 160 ° C. or higher and can improve the durability of the diaphragm. And

  The present inventors have conducted intensive studies to solve the above problems, and as a result, focused on a thermoplastic polyimide resin having a very high glass transition point, and produced a film having excellent heat resistance using a molding material containing the thermoplastic polyimide resin. Thus, the present invention has been completed.

That is, in the present invention, in order to solve the above-mentioned problems, a method for manufacturing a film for a diaphragm of a speaker, which forms a film using a resin-containing molding material,
A molding material containing a thermoplastic polyimide resin is melt-kneaded, a film is continuously extruded from a die into a band shape using the molding material, and the extruded film is brought into contact with a roll and cooled, thereby cooling. The thickness of the film is 2 μm or more and 110 μm or less,
The film after cooling has a tensile modulus at 23 ° C. of not less than 1000 N / mm ^{2 and not} more than 3000 N / mm ^2, a glass transition point of not more than 160 ° C. after cooling, and a first change in the storage modulus of the film after cooling. The inflection point temperature is from 160 ° C to 240 ° C, the tensile modulus at 160 ° C of the cooled film is from 700 N / mm ^{2 to} 2000 N / mm ^2, and the specific gravity of the cooled film is from 1.2 to 1 0.4 or less, and the loss tangent at 20 ° C. of the film after cooling is 0.010 or more and 0.4 or less.

An extruder for melting and kneading the molding material is provided, and the molding material is supplied while supplying an inert gas to the extruder.
It is preferable that the rolls be a pressure roll and a cooling roll that sandwich the film, and that the temperature of at least the cooling roll of the pressure roll and the cooling roll be adjusted to 50 ° C or more and 240 ° C or less.
In addition, when forming fine irregularities on the peripheral surface of the cooling roll and cooling the film by sandwiching the film between the pressure roll and the cooling roll, the fine irregularities of the cooling roll can be transferred to the film to reduce the friction coefficient. it can.

Alternatively, the cooled film may be laminated and adhered to an elastomer layer having a thickness of 10 μm or more and 100 μm or less, and the film and the elastomer layer may be thermoformed.
In addition, it is possible to laminate and adhere the cooled film to at least one of the two surfaces of the elastomer layer via a primer, and to form them by thermoforming.

It is also possible to use a plurality of films after cooling, and to hold the elastomer layer between the plurality of films via a primer.
Furthermore, the durometer hardness when the elastomer layer is made of a silicone resin and measured with a durometer type A according to JIS K 6253 can be A10 or more and A90 or less.

  Here, the speaker in the claims is mainly built in a portable device, and this portable device includes at least a mobile phone, a portable music device, a portable game device, a smartphone, a tablet PC, a notebook personal computer, and the like. It is. The thickness tolerance of the cooled film is preferably within a range of an average value ± 10%. Further, the number of pressure rolls and cooling rolls, which are rolls, can be increased or decreased as needed.

  Downstream of the pressure roll, a film winder is installed, and between these pressure rolls and the winder, a slit blade for forming a slit in the film to facilitate processing is arranged. A tension roll that applies tension to the film can be rotatably supported between the slit blade and the winder. The diaphragm film is used exclusively for a speaker, and the speaker is mainly of a direct radiating type that directly emits sound into the atmosphere from a diaphragm having a size approximately equal to the wavelength of sound. However, in addition to the direct radiation type, a horn type may be used. Further, the number of the elastomer layers may be one or plural.

According to the present invention, not a polyetheretherketone resin, but a thermoplastic polyimide resin having a higher glass transition temperature than this resin, a resin film is extruded, and the tensile modulus at 23 ° C. of the cooled film is determined. 1000 N / mm ² or more and 3000 N / mm ² or less, the glass transition point of the film after cooling is 160 ° C. or more, the first inflection point temperature of the storage elastic modulus after cooling is 160 ° C. or more, and the film after cooling is cooled. The tensile modulus at 160 ° C. is 700 N / mm ² or more and 2000 N / mm ² or less, the specific gravity of the film after cooling is 1.2 or more and 1.4 or less, and the loss tangent at 20 ° C. of the film after cooling is 0. Since it is 0.010 or more, heat resistance of at least 160 ° C. or more can be imparted to the film.

ADVANTAGE OF THE INVENTION According to this invention, there exists an effect that the heat resistance of 160 degreeC or more can be ensured, and the durability of a diaphragm can be improved. Further, since the glass transition point of the film after cooling is 160 ° C. or higher and the first inflection point temperature of the storage elastic modulus of the film after cooling is 160 ° C. or higher and 240 ° C. or lower, sufficient heat resistance is imparted to the film. When the diaphragm obtained from the film is used for a speaker, the high heat generated by the high vibration of the voice coil suppresses the deformation, cracking and breakage of the diaphragm obtained from the film. be able to.

  According to the second aspect of the present invention, since the inert gas is supplied during the production of the film, it is possible to prevent oxidative deterioration and oxygen crosslinking of the molding material. Further, since the temperature of the cooling roll is at least 50 ° C. or more and 240 ° C. or less, it is possible to eliminate the possibility that the film being manufactured adheres to the cooling roll and breaks. Can be expected.

  According to the third aspect of the present invention, a diaphragm obtained by laminating a film obtained from a molding material containing a thermoplastic polyimide resin on an elastomer layer having excellent sound quality characteristics and compression characteristics is manufactured. Therefore, even if the portable device is used for a long time in an unfavorable use environment for a long time, and the high power of the speaker or the like generates high heat due to the high vibration of the voice coil, the durability and sound quality characteristics of the diaphragm Can be improved. Further, since the thickness of the elastomer layer is in the range of 10 μm or more and 100 μm or less, it is possible to reduce the weight and improve the acoustic characteristics.

According to the fourth aspect of the present invention, since a silicone resin is used for the elastomer layer, it is possible to obtain a diaphragm excellent in heat resistance, weather resistance, flame retardancy, sound quality characteristics, and compression characteristics. In addition, since the durometer hardness of the silicone resin is in the range of A10 or more and A90 or less, it is possible to prevent the compression set characteristic of the silicone resin from deteriorating, and prevent the vibration propagation speed of the diaphragm from decreasing and adversely affecting sound quality. It becomes possible. Furthermore, it is possible to loss tangent may decrease, preventing the performance deterioration of the diaphragm with increasing f ₀ value.

FIG. 3 is an overall explanatory view schematically showing an embodiment of a method for manufacturing a film for a diaphragm of a speaker according to the present invention. It is sectional explanatory drawing which shows typically the diaphragm in embodiment of the manufacturing method of the film for diaphragms of the speaker which concerns on this invention. It is a graph which shows typically the relationship between 1st inflection point temperature and storage elastic modulus in the Example of the manufacturing method of the film for diaphragms of the speaker which concerns on this invention.

  Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings. A method of manufacturing a film for a diaphragm of a speaker according to the present embodiment uses a resin-containing molding material 1 as shown in FIG. This is a manufacturing method of forming a film 2 for a diaphragm. A molding material 1 containing a thermoplastic polyimide resin having excellent heat resistance in a high temperature region is melt-kneaded by a melt extruder 10, and a T-die 13 is formed by using the molding material 1. , A thin film 2 is continuously extruded, and the extruded film 2 is sandwiched between a pair of pressure rolls 17 and a cooling roll 18 and cooled to reduce the thickness of the cooled film 2 to 2 μm. The thickness is set to not less than 110 μm.

  The thermoplastic polyimide resin of the molding material 1 is not particularly limited as long as it is a crystalline polyimide resin having thermoplasticity. However, preferably, it is disclosed in Japanese Patent No. 5365672, Japanese Patent No. 6024859, or Japanese Patent No. 6037088. The polyimide resin having thermoplasticity described in the publication, and more preferably the polyimide resin having thermoplasticity described in Japanese Patent No. 6024859 or Japanese Patent No. 6037088 are preferred. Specific examples of the thermoplastic polyimide resin include a product name: Surprim series manufactured by Mitsubishi Gas Chemical Company, which has excellent strength and crystallinity, has heat resistance of 160 ° C. or more, and has a low molding temperature.

  The melting point of the thermoplastic polyimide resin is from 280 ° C to 370 ° C, preferably from 290 ° C to 350 ° C, more preferably from 300 ° C to 330 ° C. Further, the glass transition point of the thermoplastic polyimide resin is from 160 ° C to 240 ° C, preferably from 170 ° C to 210 ° C, more preferably from 170 ° C to 190 ° C.

  The reason why the melting point of the thermoplastic polyimide resin is in the range of 280 ° C. or more and 370 ° C. or less is that when the melting point of the thermoplastic polyimide resin is less than 280 ° C., the film 2 having heat resistance of 160 ° C. or more cannot be obtained. . On the other hand, when the melting point of the thermoplastic polyimide resin exceeds 370 ° C., the production temperature of the film 2 becomes 400 ° C. or more, so that the production of the film 2 becomes difficult, and moreover, usable melt extrusion molding is performed. This is because there is a problem that the machine 10 is limited.

  Further, the glass transition point of the thermoplastic polyimide resin is in the range of 160 ° C. or more and 240 ° C. or less, when the glass transition point of the thermoplastic polyimide resin is less than 160 ° C., a film 2 having heat resistance of 160 ° C. or more is obtained. Because they can't do that. On the other hand, when the glass transition point of the thermoplastic polyimide resin exceeds 240 ° C., the melting point of the thermoplastic polyimide resin exceeds 370 ° C., so that the production temperature of the film 2 becomes 400 ° C. or higher and the film 2 This is because there is a problem in the production of the melt extruder and the usable melt extruder 10 is limited.

The apparent shear viscosity of the thermoplastic polyimide resin is in the range of 1 × 10 ² Pa · s to 1 × 10 ⁴ Pa · s when the apparent shear rate at a temperature of 350 ° C. is 1 × 10 ² sec ⁻¹ , It is preferably in the range of 5 × 10 ² Pa · s to 5 × 10 ³ Pa · s, more preferably in the range of 7 × 10 ² Pa · s to 1 × 10 ³ Pa · s. This is because the apparent shear viscosity of the thermoplastic polyimide resin at a temperature of 350 ° C. and an apparent shear rate of 1 × 10 ² sec ⁻¹ is within a range of 1 × 10 ² Pa · s to 1 × 10 ⁴ Pa · s. This is because good melt extrusion can be achieved.

  As a method for producing a thermoplastic polyimide resin, a production method described in Japanese Patent No. 5,365,762, Japanese Patent No. 6024859, Japanese Patent No. 6037088, or the like is used. In addition, the thermoplastic polyimide resin, a random copolymer with other copolymerizable monomers, an alternating copolymer, a block copolymer, or a modified product may be used as long as the effects of the present invention are not impaired. Is possible. The shape of the thermoplastic polyimide resin may be any shape such as powder, flake, pellet, and lump.

  The molding material 1 containing a thermoplastic polyimide resin includes, in addition to the thermoplastic polyimide resin, a polyimide resin such as a polyimide (PI) resin, a polyamideimide (PAI) resin, and a polyetherimide (PEI) resin other than those described in the present invention. Polyamide 4T (PA4T) resin, polyamide 6T (PA6T) resin, modified polyamide 6T (PA6T) resin, polyamide 9T (PA9T) resin, polyamide 10T (PA10T) resin, polyamide 11T (PA11T) resin, polyamide 6 (PA6) resin, Polyamide resins such as polyamide 66 (PA66) resin and polyamide 46 (PA46) resin; polyester resins such as polyethylene terephthalate (PET) resin, polybutylene terephthalate (PBT) resin and polyethylene naphthalate (PEN) resin; Ketone (PEK) resin, polyether ether ketone (PEEK) resin, polyether ether ether ketone (PEEEK) resin, polyether ketone ketone (PEKK) resin, polyether ether ketone ketone (PEEKK) resin, polyether ketone ether ketone ketone (PEKEKK) resin such as polyarylene ether ketone resin, polysulfone (PSU) resin, polyethersulfone (PES) resin, polysulfone resin such as polyphenylsulfone (PPSU) resin, polyphenylene sulfide (PPS) resin, polyphenylene sulfide ketone Resin, polyarylene sulfide resin such as polyphenylene sulfide sulfone resin, polyphenylene sulfide ketone sulfone resin, liquid crystal polymer (LCP), polycarbonate PC) resin, optionally a polyarylate (PAR) resin, can be added.

  In addition, the molding material 1 contains, in addition to the above resins, an antioxidant, a light stabilizer, an ultraviolet absorber, a plasticizer, a lubricant, a flame retardant, an antistatic agent, a heat resistance improver, in addition to the above-mentioned resins, as long as the properties of the present invention are not impaired. Inorganic compounds, organic compounds and the like can be selectively added.

When a film 2 for a diaphragm is manufactured using such a molding material 1 containing a thermoplastic polyimide resin, a known manufacturing method such as a melt extrusion molding method, a calendar molding method, or a casting molding method is employed. be able to.
However, from the viewpoint of improving the thickness accuracy of the film 2, the productivity, the handling properties, and the simplification of the equipment, it is preferable to continuously extrude the thin film by the melt extrusion molding method. Here, as shown in FIG. 1, the melt extrusion method involves melting and kneading a molding material 1 using a melt extrusion molding machine 10, and a film 2 for a diaphragm from a T-die 13 of the melt extrusion molding machine 10. This is a molding method that extrudes continuously.

  The melt-extrusion molding machine 10 includes, for example, a single-screw extruder or a twin-screw extruder, and functions to melt-knead the injected molding material 1. A raw material inlet 11 for the molding material 1 is provided at the upper rear of the melt extrusion molding machine 10. The raw material inlet 11 has helium gas, neon gas, argon gas, krypton gas, nitrogen gas, carbon dioxide gas. An inert gas supply pipe 12 for supplying an inert gas (see arrows in FIG. 1) as necessary is connected, and the inert gas supplied from the inert gas supply pipe 12 causes the molding material 1 to flow. Oxidation deterioration and oxygen crosslinking are effectively prevented.

  As the melt extruder 10 such as a single screw extruder or a twin screw extruder, it is preferable to use a melt extruder 10 having a vent hole. By melting and kneading under reduced pressure using these vent holes, it becomes easy to sufficiently deaerate moisture and sublimated organic substances contained in the molding material 1. Further, it is not necessary to adjust the water content of the molding material 1 before the melt-kneading.

  The temperature of the thermoplastic polyimide resin during melt-kneading of the melt extrusion molding machine 10 is a temperature at which the thermoplastic polyimide resin can be melted, and is not particularly limited as long as the thermoplastic polyimide resin is not decomposed. A range from the melting point to the thermal decomposition temperature is preferred. Specifically, the temperature is adjusted to 280 ° C to 400 ° C, preferably 300 ° C to 380 ° C, more preferably 320 ° C to 360 ° C. This is because if the melting point of the thermoplastic polyimide resin is less than the melting point, the thermoplastic polyimide resin-containing molding material 1 cannot be melt-extruded. This is because the molding material 1 may be severely decomposed.

  The T-die 13 is attached to the distal end of the melt extrusion molding machine 10 via a connecting pipe 14, and functions to continuously extrude the belt-shaped film 2 downward. The temperature at the time of extrusion of the T-die 13 is in the range from the melting point of the thermoplastic polyimide resin to the thermal decomposition temperature. Specifically, the temperature is adjusted to 280 ° C to 400 ° C, preferably 300 ° C to 380 ° C, more preferably 320 ° C to 360 ° C. If the melting point is lower than the melting point of the thermoplastic polyimide resin, it will hinder the melt extrusion of the molding material 1 containing the thermoplastic polyimide resin. This is based on the reason that the molding material 1 may be severely decomposed.

  It is preferable that a gear pump 15 and a filter 16 are respectively mounted on the connection pipe 14 upstream of the T die 13. The gear pump 15 transfers the molding material 1 melt-kneaded by the melt extrusion molding machine 10 to the T-die 13 through the filter 16 at a constant flow rate and with high precision. In addition, the filter 16 separates the gel, foreign matter, and the like of the molten molding material 1 and transfers the molten molding material 1 to the T-die 13.

  The filter 16 is made of, for example, a circular shape having a large number of holes in a concentric circle, a sintered metal having a large number of holes, or a metal mesh, and is 0.5 to 6 times the average thickness of the film 2, preferably It has a plurality of small openings of 0.5 times or more and 4 times or less, more preferably 0.5 times or more and 3.8 times or less. The reason why the opening of the filter 16 is 0.5 times or more is that when the opening is less than 0.5 times, the extrusion pressure of the molding material 1 is increased, so that the filter 16 may be damaged, and the productivity is significantly reduced. Because you do.

  The pair of pressure rolls 17 is rotatably supported below the T-die 13 and slidably holds the cooling roll 18. A winding tube 20 of a winder 19 for winding the film 2 is rotatably installed further downstream of the downstream pressure roll 17 of the pair of pressure rolls 17. A slit blade 21 that forms a slit on the side of the film 2 is arranged between the winding blade 20 and the winding tube 20 so that the slit blade 21 can move up and down. A required number of rotatable tension rolls 22 for applying a tension to the film 2 and smoothly winding the film 2 are supported.

  A rubber layer of at least a natural rubber, an isoprene rubber, a butadiene rubber, a silicone rubber, a fluorine rubber, or the like is provided on the peripheral surface of each of the press rolls 17 as necessary from the viewpoint of improving the adhesion between the film 2 and the cooling roll 18. A film is formed, and an inorganic compound such as silica or alumina is selectively added to the rubber layer. Among these, it is preferable to use silicone rubber or fluorine rubber having excellent heat resistance.

  As the pressing roll 17, a metal elastic roll having a metal surface is used as necessary. When this metal elastic roll is used, the film 2 having a surface having excellent smoothness can be formed. Specific examples of the metal elastic roll include, for example, a metal sleeve roll, an air roll (product name manufactured by Dimco), and a UF roll (product name manufactured by Hitachi Zosen Corporation).

  Such a pressure roll 17 is adjusted to a temperature of 240 ° C. or less, preferably 50 ° C. or more and 220 ° C. or less, more preferably 130 ° C. or more and 200 ° C. or more, and still more preferably 160 ° C. or more and 200 ° C. or less. This is pressed against the cooling roll 18. The range of the temperature of the pressure roll 17 is that when the temperature of the pressure roll 17 exceeds 240 ° C., the film 2 being manufactured is stuck to the pressure roll 17 and the film 2 is broken or coated on the pressure roll 17. It is based on the reason that the formed rubber layer may be thermally decomposed.

  Conversely, if the temperature of the pressure-bonding roll 17 is lower than 50 ° C., the pressure-bonding roll 17 is condensed, which is not preferable. Examples of the method of adjusting the temperature and cooling of the pressing roll 17 include a method using a heat medium such as air, water, and oil, or an electric heater or a dielectric heating roll.

  The cooling roll 18 is made of, for example, a metal roll having a diameter larger than that of the pressing roll 17. The cooling roll 18 is rotatably supported below the T-die 13 and holds the extruded film 2 between the cooling roll 18 and the pressing roll 17. The function is to control the thickness of the film 2 within a predetermined range while cooling the film 2 together with the roll 17. This cooling roll 18 is adjusted to a temperature of 240 ° C. or less, preferably 50 ° C. or more and 220 ° C. or less, more preferably 130 ° C. or more and 200 ° C. or more, and still more preferably 160 ° C. or more and 200 ° C. or less, like the pressure roll 17; It comes into sliding contact with the film 2.

  The reason why the temperature of the cooling roll 18 is adjusted to 50 ° C. or more and 240 ° C. or less is that when the temperature of the cooling roll 18 exceeds 240 ° C., the film 2 being manufactured adheres to the cooling roll 18 and the film 2 is broken. This is because the rubber layer of the pressure roll 17 may be thermally decomposed in the case of the pressure roll 17 having the rubber layer coated thereon. On the other hand, if the temperature of the cooling roll 18 is lower than 50 ° C., condensation of the cooling roll 18 is caused, which is not preferable. The method of adjusting the temperature and cooling of the cooling roll 18 may be a method using a heat medium such as air, water, or oil, or an electric heater or induction heating.

  In the above, when manufacturing the film 2 for a diaphragm, as shown in FIG. 1, first, a molding material 1 containing a thermoplastic polyimide resin is supplied to a raw material inlet 11 of a melt extrusion molding machine 10 by an arrow in the figure. Is supplied while supplying an inert gas indicated by (1), the molding material 1 is melt-kneaded in a heated and pressurized state by a melt extruder 10, and the thin film 2 is continuously extruded from the T-die 13 into a band shape.

  At this time, the water content of the molding material 1 containing the thermoplastic polyimide resin before melt extrusion is adjusted to 2000 ppm or less, preferably 1000 ppm or less, more preferably 100 ppm or more and 500 ppm or less. This is because if the moisture content of the thermoplastic polyimide resin before melt extrusion exceeds 2000 ppm, the film 2 may foam immediately after being extruded from the T-die 13. The lower limit of the water content of the molding material 1 before melt-kneading is not particularly limited, but is preferably 100 ppm or more.

  After the belt-shaped film 2 is extruded, the film 2 is sequentially wound around a pair of pressure rolls 17, a cooling roll 18, a tension roll 22, and a winding tube 20 of a winder 19, and the film 2 is cooled by the cooling roll 18. By cutting both side portions of each of them with a slit blade 21 and winding them sequentially around a winding tube 20, a film 2 for a diaphragm made of a thermoplastic polyimide resin can be manufactured. During the production of the film 2, fine irregularities are formed on the surface of the film 2 as long as the effects of the present invention are not lost, and the friction coefficient of the surface of the film 2 can be reduced.

  As a method of forming fine irregularities, (1) a method of forming the fine irregularities by sandwiching the film 2 between a cooling roll 18 having fine irregularities and a pressing roll 17 having fine irregularities, (2) A method of spraying an inorganic compound such as zirconia, glass, stainless steel, or the like, a polycarbonate resin, a polyamide resin, or an organic compound such as a seed of a plant on the film 2 to form fine unevenness; Press molding with a provided die to form fine irregularities. Among these methods, the method (1) is preferable from the viewpoint of simplification of equipment, accuracy of unevenness size, uniformity of unevenness formation, ease of unevenness formation, and continuous formation of unevenness.

  The method (1) will be described in more detail. (1-1) A molding material 1 containing a thermoplastic polyimide resin is formed from a T-die 13 of a melt extruder 10 on a cooling roll 18 having fine irregularities on its peripheral surface. A method in which the discharged material is sandwiched between a cooling roll 18 and a pressure roll 17 having fine irregularities on its peripheral surface, and is formed simultaneously with the melt extrusion of the film 2; There is a method of forming the unevenness by sandwiching between a cooling roll 18 having fine irregularities on the peripheral surface and a pressure roll 17 having fine irregularities on the peripheral surface, and from the viewpoint of simplification of equipment, (1-1) Is preferred.

  The thickness of the thermoplastic polyimide resin film 2 after cooling is in the range of 2 μm to 110 μm, preferably 5 μm to 100 μm, more preferably 8 μm to 75 μm. This is because if the thickness of the film 2 is less than 2 μm, the mechanical strength of the film 2 is significantly reduced, and it becomes difficult to form the film 2. Conversely, if the thickness of the film 2 exceeds 110 μm, the diaphragm becomes thick and large, and the size of the speaker also increases, which makes it unsuitable for a speaker for a portable device. The thickness of the film 2 can be measured by various contact-type thickness gauges.

  The thickness tolerance of the film 2 is preferably within a range of an average value ± 10%, and more preferably within a range of an average value ± 5%. This is because if the thickness intersection of the film 2 is out of the range of the average value ± 10%, the sound quality varies. The thickness tolerance of the film 2 can be obtained by a predetermined formula.

The mechanical properties of the thermoplastic polyimide resin film 2 after cooling can be evaluated by the tensile modulus at 23 ° C. Tensile modulus at 23 ° C. of the thermoplastic polyimide resin film 2 after cooling, 1000 N / mm ² or more 3000N / mm ² or less, preferably in the range of 1500 N / mm ² or more 2500N / mm ^2, more preferably in the range of 1700 N / mm ² or more 2300N / mm ² or less in the range is optimal.

This is based on the reason that when the tensile elastic modulus of the film 2 is less than 1000 N / mm ² , the high-band resonance frequency (f _H ) of the diaphragm of the film 2 is low, and high-frequency sound reproduction is insufficient. If it exceeds 3000 N / mm ² , it is based on the reason that the lowest resonance frequency (f ₀ ) of the diaphragm obtained from the film 2 is high and bass reproduction becomes insufficient.

  The heat resistance of the thermoplastic polyimide resin film 2 after cooling can be evaluated by the glass transition point, the first inflection point temperature of the storage modulus, and the tensile modulus at 160 ° C. The glass transition point of the thermoplastic polyimide resin film 2 after cooling is 160 ° C. or higher, preferably 165 ° C. or higher, and more preferably 170 ° C. or higher. This is because, when the glass transition point of the film 2 is lower than 160 ° C., the heat resistance of the film 2 is insufficient, so that when the diaphragm obtained from the film 2 is used for a speaker, the voice coil has high vibration. This is because the generated high heat causes a problem in durability, such as causing deformation, cracking or breakage of the diaphragm obtained from the film 2. The upper limit of the first inflection point temperature of the storage modulus of the film 2 is not particularly limited, but is preferably 240 ° C. or lower.

  The first inflection point temperature of the storage modulus of the thermoplastic polyimide resin film 2 after cooling is 160 ° C. or higher, preferably 165 ° C. or higher, and more preferably 170 ° C. or higher. This is because when the first inflection point temperature of the storage elastic modulus of the film 2 is less than 160 ° C., the heat resistance of the film 2 becomes insufficient, and when the diaphragm obtained from the film 2 is used as a speaker, This is because the high heat generated by the high vibration of the coil causes the deformation, cracking, or breakage of the diaphragm obtained from the film 2 to cause a decrease in durability. The upper limit of the first inflection point temperature of the storage modulus of the film 2 is not particularly limited, but is preferably 240 ° C. or lower.

The tensile modulus at 160 ° C. of the thermoplastic polyimide resin film 2 after cooling is 700 N / mm ² or more and 2000 N / mm ² or less, preferably 900 N / mm ² or more and 1800 N / mm ² or less, more preferably 1000 N / mm ² or more. ^The optimum range is ² or more and 1600 N / mm ² or less.

This is because when the tensile modulus at 160 ° C. of the film 2 is less than 700 N / mm ² , the heat resistance of the film 2 is insufficient, so that when the diaphragm obtained from the film 2 is used for a speaker, This is based on the reason that the high heat generated by the high vibration of the coil causes a problem in durability, such as deformation, cracking or breakage of the diaphragm obtained from the film 2. In addition, the high-band resonance frequency of the film 2 made of the diaphragm (f _H) is low, because the treble reproduction becomes insufficient. On the other hand, if it exceeds 2000 N / mm ² , it is based on the reason that the lowest resonance frequency (f ₀ ) of the diaphragm obtained from the film 2 is high and bass reproduction becomes insufficient.

  The acoustic characteristics of the thermoplastic polyimide resin film 2 after cooling can be evaluated by the specific gravity of the film 2 at 23 ° C. and the loss tangent of the film 2 at 20 ° C. The specific gravity of the cooled film 2 is preferably 1.2 or more and 1.4 or less. This is because, in such a range, the density is small, so that a reduction in weight can be expected, the vibration propagation speed is increased, and the reproduction frequency band is widened, so that good sound quality and acoustic characteristics can be obtained.

  The loss tangent at 20 ° C. of the thermoplastic polyimide resin film 2 after cooling is 0.010 or more, preferably 0.011 or more, and more preferably 0.012 or more. This is because when the loss tangent is less than 0.010, the sound quality characteristics vary due to the occurrence of resonance. The upper limit of the loss tangent is not particularly limited, but is preferably 0.4 or less.

  Although the manufactured film 2 can be used as it is as a diaphragm of a speaker, from the viewpoint of obtaining excellent sound quality characteristics, compression characteristics, and loss tangent, it is used as a part of the laminated intermediate 3 shown in FIG. Preferably, the body 3 is formed to be a diaphragm of a speaker. As shown in FIG. 2, the laminated intermediate 3 has an elastomer layer 4 having a thickness of 10 μm or more and 100 μm or less that determines the sound quality, and a pair of upper and lower layers which are respectively laminated and adhered to the front and back surfaces of the elastomer layer 4 via the primer 5. The film 2 is provided in a multilayer structure, and is mainly used for incorporating a portable device.

  Examples of the elastomer used for the elastomer layer 4 include a silicone resin, a urethane resin, an acrylic resin, a fluorine resin, a polyester resin, a polyamide resin, a hydrocarbon resin, a styrene resin, a vinyl chloride resin, and a vinyl acetate resin. Among these elastomers, silicone resins are preferred because they are excellent in heat resistance, weather resistance, flame retardancy, sound quality characteristics, compression characteristics and the like.

  The silicone resin used for the elastomer layer 4 is made of a silicone resin composition, and the silicone resin composition is preferably a heat-curable silicone resin from the viewpoint of suitability for production of the laminated intermediate 3 and storage suitability after production. Examples of the heat-curable silicone resin include an addition-curable millable silicone resin and an addition-curable liquid silicone resin.

  The addition-curable millable silicone resin is usually composed of an organopolysiloxane, a silica-based filler, and a curing agent (a curing agent obtained by combining a known platinum-based catalyst with an organohydrogenpolysiloxane, and an organic oxide). ) And various additives such as silica fine powder.

In contrast, an addition-curable liquid silicone resin contains an organopolysiloxane containing at least two alkenyl groups bonded to silicon atoms in one molecule, and an organopolysiloxane containing at least two hydrogen atoms bonded to silicon atoms in one molecule. And inorganic fillers having an average particle diameter of 1 μm or more and 30 μm or less and a bulk density of 0.1 g / cm ³ or more and 0.5 g / cm ³ or less (diatomaceous earth, pearlite, pulverized expanded pearlite) , Mica, calcium carbonate, glass flakes, hollow fillers, etc.) and addition reaction catalysts (platinum black, platinum chloride, chloroplatinic acid, reactants of chloroplatinic acid and monohydric alcohol, chloroplatinic acid and olefins) With platinum complex, platinum bisacetoacetate, palladium-based catalyst, rhodium-based catalyst, etc.) It is.

  The silicone resin composition to be used as the silicone resin is prepared by using a kneader such as a calender roll such as a two-roller or a three-roller, a roll mill, a Banbury mixer, or a dough mixer (kneader), and, if desired, various additives. Until it is uniformly mixed, for example, for several minutes to several hours, preferably for 5 minutes to 1 hour, by kneading at room temperature or under heating. The ordinary temperature here refers to a temperature range of about 0 to 50 ° C.

  The thickness of the elastomer layer 4 is optimally 10 μm or more and 100 μm or less, preferably 20 μm or more and 80 μm or less, more preferably 50 μm or more and 75 μm or less, from the viewpoint of obtaining excellent acoustic characteristics by weight reduction. The thickness here refers to the thickness after curing when a silicone resin is used for the elastomer layer 4.

  The durometer hardness of the silicone resin when the silicone resin is used for the elastomer layer 4 is A10 or more and A90 or less, preferably A20 or more and A70 or less, more preferably A20 or more and A70 or less when measured with a durometer type A in accordance with JIS K6253. The range from A20 to A50 is optimal. This is because, if the durometer hardness is less than A10, the compression set characteristic of the silicone resin layer is deteriorated, and the vibration propagation speed of the diaphragm is reduced, causing a problem in sound quality. On the other hand, if the durometer hardness exceeds A90, the loss tangent becomes small, and the performance as a diaphragm is deteriorated.

  The primer 5 is interposed between the elastomer layer 4 and the film 2 made of a thermoplastic polyimide resin, and functions to firmly adhere them. The primer 5 is not particularly limited as long as it can bond the silicone resin and the film 2 made of a thermoplastic polyimide resin. Examples of the primer 5 include alkyd resins and alkyd resins such as phenol-modified and silicone-modified. Modified products, oil-free alkyd resins, acrylic resins, silicone resins, epoxy resins, fluororesins, phenolic resins, silane coupling agents, titanate coupling agents, aluminum coupling agents, mixtures thereof, and the like. Examples of the crosslinking agent for curing and / or crosslinking these resins include isocyanate compounds, melamine compounds, epoxy compounds, peroxides, phenol compounds, hydrogen siloxane compounds, silane compounds and the like.

  The primer 5 is used in a state of a mixture comprising the above compound and an organic solvent. As the organic solvent, a solvent which is easy to volatilize is preferable. For example, alcohol solvents such as methanol, ethanol or isopropanol, aromatic hydrocarbon solvents such as xylene or toluene, n-hexane, cyclohexane, methylcyclohexane, or dimethylcyclohexane And ketone solvents such as acetone and methyl ethyl ketone, and ester solvents such as ethyl acetate and butyl acetate. These organic solvents may be used alone or in combination of two or more. The amount of the organic solvent to be added is appropriately adjusted to an appropriate concentration according to the method of applying the primer 5.

  The primer 5 may be applied to any of the opposing surfaces of the silicone resin and the thermoplastic polyimide resin film 2 by, for example, a spray method, a brush coating method, a gravure coating method, a die coating method, a bar coater (Meyer bar) method, an impregnation coating method. A thin layer is formed after the organic solvent is volatilized by a known method such as the method described above.

  The primer 5 of the thin film layer has a thickness of 0.1 μm or more and 5 μm or less, preferably 1 μm or more and 3 μm or less. This is because if the thickness of the primer 5 is less than 0.1 μm, the adhesion between the elastomer layer 4 and the film 2 becomes insufficient, and the primer 5 may be peeled off during molding into a diaphragm or during use. Because. On the other hand, if the thickness of the primer 5 exceeds 5 μm, the secondary formability to the diaphragm or the acoustic characteristics may be adversely affected.

  When it is desired to improve and improve the wettability of the primer 5 with respect to the elastomer layer 4 and the film 2, the surfaces of the elastomer layer 4 and the film 2 are treated by various surface treatment methods as long as the properties of the present invention are not impaired. Just do it. Examples of various surface treatment methods include known methods such as corona irradiation treatment, ultraviolet irradiation treatment, plasma irradiation treatment, excimer laser treatment, flame treatment, flame treatment, and itro treatment.

  The thickness of the pair of films 2 may be different on both surfaces of the elastomer layer 4 or may be equal, but preferably equal. This is because when the thickness of the pair of films 2 is different, the heat shrinkage of the films 2 is different, and the diaphragm may be curled after molding.

  As a method for producing such a laminated intermediate 3, first, an elastomer used for the elastomer layer 4 is formed into a sheet shape, and this elastomer and a pair of films 2 already formed are interposed via a primer 5. Laminate. As a method for forming the elastomer into a sheet, a known production method such as a normal temperature extrusion molding method, a melt extrusion molding method, a calendar molding method, or a casting molding method can be employed.

  When there is a problem in handling properties such as low mechanical properties of the elastomer used for the elastomer layer 4 or severe stickiness, the elastomer is coated on a non-stretchable base sheet such as a polyethylene terephthalate (PET) resin sheet. May be divided into a predetermined thickness. The ordinary temperature here refers to a temperature range of 0 to 50 ° C.

  When the elastomer of the elastomer layer 4 is, for example, a silicone resin, first, a silicone resin composition is prepared and kneaded by using two or three calender rolls, and the kneaded silicone resin composition is made of a non-stretchable material such as a polyethylene terephthalate resin sheet. Is separated into a sheet having a predetermined thickness by a calender roll on the base sheet of the above, and a film 2 made of a thermoplastic polyimide resin, which has been already molded, is placed on the exposed surface of the silicone resin composition through a primer 5. Laminate.

  Next, the base sheet is placed on the film 2 side, the base sheet is peeled off to expose the adhesive surface of the silicone resin composition, and the exposed surface of the silicone resin composition is coated with another film 2 made of thermoplastic polyimide resin. Are laminated via the primer 5, the laminated intermediate 3 can be produced.

  When the laminated intermediate 3 is manufactured, the laminated intermediate 3 is formed into a diaphragm by a known thermoforming method such as press molding using a mold, vacuum forming, vacuum pressure forming method, or pressure forming. A small speaker diaphragm without wrinkles can be manufactured. At this time, when a silicone resin is used for the elastomer layer 4, the silicone resin is cured at the same time as the formation of the diaphragm, and if the silicone resin is adjusted to a predetermined size and shape, a small-sized speaker diaphragm without wrinkles is manufactured. can do.

  The thermoforming temperature of the laminated intermediate 3 is equal to or higher than the glass transition point and lower than the melting point of the thermoplastic polyimide resin film 2 from the viewpoint of moldability into a diaphragm. Specifically, the temperature is from 160 ° C to 300 ° C, preferably from 180 ° C to 280 ° C. This is because when the thermoforming temperature is lower than the glass transition point temperature of the film 2, it is difficult to form the laminated intermediate 3 into a diaphragm, and when the thermoforming temperature is higher than the melting point of the film 2, This is because the film 2 is melted to lower the shape, or the elastomer used for the elastomer layer 4 is thermally decomposed or denatured.

According to the above, the film 2 is melt-extruded with a thermoplastic polyimide resin in a high-temperature range, and the tensile elasticity at 23 ° C. of the cooled film 2 is set to 1000 N / mm ² or more and 3000 N / mm ² or less. The glass transition point of the film 2 is 160 ° C. or more and 240 ° C. or less, the first inflection point temperature of the storage elastic modulus of the film 2 after cooling is 160 ° C. or more and 240 ° C. or less, and the 160 ° C. , The tensile modulus of the film 2 after cooling is 700 N / mm ² or more and 2000 N / mm ² or less, the specific gravity of the film 2 after cooling is 1.2 or more and 1.4 or less, and the loss tangent at 20 ° C. of the film 2 after cooling is 0.010 As described above, at least heat resistance of 160 ° C. or more, generally 170 ° C. or more can be imparted to the film 2.

  Therefore, even if the film 2 is used as a diaphragm of a speaker, the risk of deformation or breakage of the diaphragm due to high heat associated with high vibration of the voice coil can be effectively eliminated.

  Further, a pair of thermoplastic polyimide resin films 2 are laminated on the elastomer layer 4 having excellent sound quality characteristics and compression characteristics to manufacture a diaphragm having both of these characteristics. The durability and sound quality characteristics of the diaphragm can be improved even when the speaker is used for a long time and the external output increases with the enhancement of the function and the output of the speaker, and the heat generated by the high vibration of the voice coil is generated.

  In particular, a silicone resin having excellent heat resistance, weather resistance, flame retardancy, sound quality characteristics, compression characteristics, and the like is used for the elastomer layer 4, and a pair of thermoplastic polyimide resin films 2 is laminated on the silicone resin to obtain these characteristics. If a diaphragm with both the above characteristics is manufactured, even if the portable device is used for an unfavorable use environment for a long time, the external output increases with the high performance and high output of the speaker, and the high heat due to the high vibration of the voice coil is reduced. Even if this occurs, the heat resistance and acoustic characteristics of the diaphragm can be significantly improved.

  In the above-described embodiment, the diaphragm has a multilayer structure including the elastomer layer 4 and the films 2 laminated and bonded to both surfaces of the elastomer layer 4 via the primers 5, but the invention is not limited to this. Not something. For example, only the film 2 may be used, and the elastomer layer 4 may be omitted. Further, on the surface of the film 2, various antistatic agents, various kinds of elastomers such as silicone resin, acrylic resin, urethane resin and the like are applied as long as the effects of the present invention are not lost, or aluminum, tin, nickel, copper, etc. Various metals may be deposited. Further, a plurality of discs, meshes, and the like of the filter 16 are selectively laminated as needed. The opening shape of the filter 16 is not particularly limited to a circle, an ellipse, a rectangle, a polygon, or the like.

Hereinafter, examples of the method for manufacturing a film for a diaphragm of a speaker according to the present invention will be described together with comparative examples.
[Example 1]
First, a commercially available thermoplastic polyimide resin (Mitsubishi Gas Chemical Co., Ltd. product name: Surprim TO-65) was prepared as a molding material, and the thermoplastic polyimide resin was dried for 12 hours with a hot air dryer heated to 160 ° C., and dried. After confirming that the moisture content of the formed molding material is 300 ppm or less, the dried thermoplastic polyimide resin is set in a φ40 mm single-screw extruder equipped with a T-die having a width of 900 mm, and melt-kneaded. The thermoplastic polyimide resin thus obtained was continuously extruded from a T-die of a single screw extruder to extrude a thermoplastic polyimide resin film as a diaphragm film into a 6.2 μm-thick strip.

  The glass transition point of the thermoplastic polyimide resin was determined by using a differential scanning calorimeter (manufactured by SII NanoTechnology Inc .: product name high-sensitivity differential scanning calorimeter X-DSC7000) according to JIS K7121, and the temperature rising rate was 10 ° C. / Min. Further, the melting point (also referred to as melting temperature) of the thermoplastic polyimide resin was determined by the same method as the glass transition temperature. The glass transition point of this thermoplastic polyimide resin was 173 ° C, and the melting point was 324 ° C.

  At this time, the moisture content of the thermoplastic polyimide resin was measured by a Karl Fischer titration method using a trace moisture measuring device [Model CA-100, manufactured by Mitsubishi Chemical Corporation]. The single-screw extruder was L / D = 32, compression ratio: 2.5, and screw: full flight screw type. The temperature of the single-screw extruder was adjusted to 340 ° C. to 355 ° C., the temperature of the T-die was adjusted to 355 ° C., and the temperature of the connecting pipe connecting the single-screw extruder and the T-die was adjusted to 355 ° C.

  A gear pump and a filter were attached to the connecting pipe, and the temperature of the gear pump was adjusted to 355 ° C. When the thermoplastic polyimide resin was charged into the single screw extruder, 18 L / min of nitrogen gas was supplied. The temperature of the molten thermoplastic polyimide resin was 353 ° C. when the resin temperature at the entrance of the T-die was measured.

  The apparent shear viscosity of the thermoplastic polyimide resin was measured using a twin-capillary rheometer R6000 (trade name, manufactured by IMATEK) after drying the thermoplastic polyimide resin at 160 ° C. for 12 hours. Specifically, first, at a capillary die: φ1.0 mm × 16 mm (long die), φ1.0 mm × 0.25 mm (short die), barrel diameter: 15 mm, temperature: 350 ° C., a thermoplastic polyimide resin is placed in the barrel. 40 g was charged, and the piston was pushed at a speed of 50 mm / min until the long die side: 0.9 MPa and the short die side: 0.3 MPa. When the pressure reached a predetermined value, the state was maintained for 6 minutes.

Thereafter, the piston is again pushed at a speed of 50 mm / min until the long die side: 0.9 MPa and the short die side: 0.3 MPa, and when the pressure reaches a predetermined value, a predetermined apparent shear rate (10, 20, 30, 50, 80, 100, 200, 300, and 800 sec ^-1 ), and the apparent shear viscosity was determined. The apparent shear viscosity of the thermoplastic polyimide resin when the apparent shear rate was 100 sec ^-1 was 1320 Pa · s.

  After extrusion molding of the thermoplastic polyimide resin film, both sides of the continuous thermoplastic polyimide resin film are cut with slit blades and sequentially wound around a winding tube of a winding machine, and the length is 100 m and the width is 650 mm. A film made of a thermoplastic polyimide resin was manufactured. At this time, the film is sequentially wound around a pair of pressure rolls made of silicone rubber, a metal roll which is a cooling roll at 150 ° C. having irregularities on the peripheral surface, and a 3-inch winding pipe located downstream of these. , Between a pressure roll and a metal roll.

  When a film made of a thermoplastic polyimide resin, which is a film for a diaphragm, was obtained, the film thickness, film thickness crossing, mechanical properties, heat resistance properties, and acoustic properties of this film were evaluated, and the results are shown in Table 1. . The mechanical properties are the tensile modulus of the film at 23 ° C, the heat resistance is the glass transition point of the film, the first inflection point of the storage modulus and the tensile modulus of the film at 160 ° C, and the acoustic properties are the film at 23 ° C. Evaluation was made based on the specific gravity and the loss tangent at 20 ° C. of the film.

・ Film thickness of the film The thickness of the film having a film thickness of 10 μm or less is measured using a contact-type thickness gauge [product of Marh, product name: Millimar 1240, a compact amplifier equipped with a millimar inductive probe 1301]. did. On the other hand, the thickness of the film having a film thickness of more than 10 μm to 110 μm or less was measured using a micrometer [Mitutoyo Co., Ltd. product name: coolant proof micrometer code MDC-25PJ].

  In the measurement, the thickness at a predetermined position where the extrusion direction of the film and the width direction (the direction perpendicular to the extrusion direction) intersect was measured at 20 points, and the average value was defined as the film thickness. The measurement points in the extrusion direction were 100 mm, 200 mm, 300 mm, 400 mm, and 500 mm from the leading end of the film. On the other hand, the measurement point in the width direction is 25 mm from the left end of the film, and then 55 mm, 85 mm, 115 mm, 145 mm, 175 mm, 205 mm, 235 mm, 265 mm, 295 mm, 325 mm, 355 mm, 385 mm, 415 mm, 445 mm at intervals of 30 mm. 475 mm, 505 mm, 535 mm, 565 mm, and 595 mm.

-Film thickness tolerance The film thickness tolerance was determined from the following equation.
Film thickness tolerance [%] = {(MAX or MIN) − (AVE)} / (AVE) × 100
Here, MAX: maximum value of film thickness
MIN: minimum value of film thickness
AVE: Average value of film thickness When the obtained film thickness tolerance was within ± 5%, it was evaluated as A, when it was within ± 5-10%, B, and when it exceeded ± 10%, it was evaluated as NG.

-Tensile modulus at 23 ° C of the film The tensile modulus at 23 ° C of the film was measured in the extrusion direction and the width direction (perpendicular to the extrusion direction) of the film. This tensile modulus was measured in accordance with JIS K7127 under the conditions of a tensile speed of 50 mm / min and a temperature of 23 ° C.

-Glass transition point of film Regarding the glass transition point of the film, the loss elastic modulus (E ") of the film was measured, and the temperature at which the measured value reached a maximum was taken as the glass transition point. The loss modulus was measured in the extrusion direction and the width direction (perpendicular to the extrusion direction), and the loss modulus was measured in the extrusion direction and the width direction (perpendicular to the extrusion direction).

  Specifically, when measuring the loss elastic modulus in the extrusion direction of the film, the extrusion direction is 60 mm × 6 mm in the width direction, and when the loss elastic modulus in the width direction is measured, the extrusion direction is 6 mm × 60 mm in the width direction. It was cut out and measured. In the measurement of the loss elastic modulus, the frequency was 1 Hz, the strain was 0.1%, and the heating rate was 3 in a tensile mode using a viscoelastic spectrum meter (trade name: RSA-G2 manufactured by TS Instrument Japan). C./min, measurement temperature range: -60 to 360.degree.

-The first inflection point temperature of the storage elastic modulus (E ') of the film The first inflection point temperature of the storage elastic modulus of the film was measured in the extrusion direction and the width direction (perpendicular to the extrusion direction) of the film. Specifically, when measuring the storage elastic modulus in the extrusion direction of the film, the extrusion direction is 60 mm × width direction 6 mm. When the storage elastic modulus in the width direction is measured, the extrusion direction is 6 mm × width direction 60 mm. It was cut out and measured.

  In the measurement of the storage elastic modulus, a frequency of 1 Hz, a strain of 0.1%, and a heating rate were measured in a tensile mode using a viscoelastic spectrum meter (trade name: RSA-G2 manufactured by TS Instrument Japan Co., Ltd.). The measurement was performed at 3 ° C./min, a measurement temperature range of −60 to 360 ° C., and a distance between chucks of 21 mm.

  As shown in FIG. 3, the first inflection point temperature was the temperature at the intersection of two straight line portions extending from the storage elastic modulus change curve. Specifically, first, the straight line portion before the storage elastic modulus suddenly drops first is extended to the high temperature side, and the first straight line (a) is drawn. Next, a straight line (b) is drawn by extending the straight line portion after the storage elastic modulus has sharply dropped first to the low temperature side. Then, a vertical line at the intersection of both lines (a) and (b) was drawn on the horizontal temperature axis, and the temperature was determined as the first inflection point temperature.

-Tensile modulus at 160 ° C of the film The tensile modulus at 160 ° C of the film was measured in the extrusion direction and the width direction (perpendicular to the extrusion direction) of the film. As a test piece for measurement, JIS K71603 type was used. Specifically, a test piece was cut out from the film in the form of JIS K71603, and the test piece was attached to a tensile tester equipped with a constant temperature bath heated at 160 ° C. in advance and measured at a pulling speed of 50 mm / min in accordance with JIS K7127. . The measurement was performed after the test piece was attached to the knob of the tensile tester in the thermostat, the door of the thermostat was closed, and after the temperature of the thermostat reached 160 ± 2 ° C., the test piece was left for 3 minutes.

-Specific gravity of the film The specific gravity of the film at 23 ° C was measured at a temperature of 23 ° C in accordance with the measurement method of JIS K7112 (Method A).

-Loss tangent of the film The loss tangent of the film was measured in the extrusion direction and the width direction (perpendicular to the extrusion direction). Specifically, when measuring the loss tangent in the extrusion direction of the film, the extrusion direction is 60 mm × 6 mm in the width direction, and when measuring the loss tangent in the width direction, the film is 6 mm in the extrusion direction × 60 mm in the width direction. It was cut out and measured. When measuring the loss tangent, the frequency was 1 Hz, the strain was 0.1%, and the heating rate was 3 in a tensile mode using a viscoelastic spectrometer (trade name: RSA-G2, manufactured by TS Instruments Japan). The measurement was carried out under the conditions of ° C / min, a measurement temperature range of -60 to 360 ° C, and a check interval of 21 mm, and a loss tangent at 20 ° C was determined.

[Example 2]
In the case of Example 1, the molding material was continuously extruded from the T-die of the single screw extruder to extrude a 6.2 μm-thick thermoplastic polyimide resin film. Extruded a film having a thickness of 12.6 μm. The other parts were the same as in Example 1.
When a film was obtained, the film thickness, film thickness tolerance, mechanical properties, heat resistance properties, and acoustic properties of this film were evaluated in the same manner as in Example 1, and the results are shown in Table 1.

[Example 3]
In the case of Example 1, the molding material was continuously extruded from the T-die of the single screw extruder to extrude a thermoplastic polyimide resin film having a thickness of 6.2 μm. Extruded a film having a thickness of 30.3 μm. Further, in the case of Example 1, the temperature of the metal roll, which is a cooling roll having irregularities on the peripheral surface, was set to 150 ° C., but in the case of Example 3, the temperature of the metal roll was changed to 160 ° C. . The other parts were the same as in Example 1.
When a film was obtained, the film thickness, film thickness tolerance, mechanical properties, heat resistance properties, and acoustic properties of this film were evaluated in the same manner as in Example 1, and the results are shown in Table 1.

[Example 4]
In the case of Example 1, the molding material was continuously extruded from the T-die of the single screw extruder to extrude a thermoplastic polyimide resin film having a thickness of 6.2 μm. Extruded a film having a thickness of 74.9 μm. Further, in the case of Example 1, the temperature of the metal roll, which is a cooling roll having irregularities on the peripheral surface, was set to 150 ° C., but in the case of Example 4, the temperature of the metal roll was changed to 180 ° C. . The other parts were the same as in Example 1.
When a film was obtained, the film thickness, film thickness tolerance, mechanical properties, heat resistance properties, and acoustic properties of this film were evaluated in the same manner as in Example 1, and the results are summarized in Table 1.

[Example 5]
In the case of Example 1, the molding material was continuously extruded from the T-die of the single screw extruder to extrude a thermoplastic polyimide resin film having a thickness of 6.2 μm. Extruded a 100 μm thick film. The temperature of the metal roll, which is a cooling roll having irregularities on the peripheral surface, was set to 180 ° C. as in Example 4, and the other parts were set to the same as in Example 1.
When a film was obtained, the film thickness, film thickness tolerance, mechanical properties, heat resistance properties, and acoustic properties of this film were evaluated in the same manner as in Example 1, and the results are summarized in Table 1.

[Comparative Example 1]
First, a commercially available polyetheretherketone resin (Victrex Corporation product name: Victrex Peak 381G (hereinafter abbreviated as "381G")) was prepared as a molding material, and the molding material was dried with hot air in the same manner as in Example 1. After drying at 160 ° C. for 12 hours with a machine and confirming that the moisture content of the dried molding material was 300 ppm or less, the dried polyetheretherketone resin was subjected to the same single-screw extruder as in Example 1. A belt-shaped film made of polyetheretherketone resin was extruded by using a T die.

  The temperature of the single-screw extruder was adjusted to 380 to 400 ° C, the temperature of the T-die was adjusted to 400 ° C, and the temperature of the connecting pipe connecting the single-screw extruder and the T-die was adjusted to 400 ° C. A gear pump and a filter were mounted on the connecting pipe, and the temperature of the gear pump and the filter was adjusted to 400 ° C. The water content of the polyetheretherketone resin was measured in the same manner as in Example 1. Regarding the temperature of the molten polyetheretherketone resin, the resin temperature at the inlet of the T-die was measured, and it was 397 ° C.

  After extrusion-molding a film made of polyetheretherketone resin, both sides of the continuous film are cut with a slit blade and sequentially wound around a winding tube of a winder, and are 100 m long and 650 mm wide polyetheretherketone. A resin diaphragm film was manufactured. At this time, the film is sequentially wound around a pair of pressure-bonding rolls made of silicone rubber, a metal roll which is a 210 ° C. cooling roll having irregularities on the peripheral surface, and a 3-inch winding tube located downstream of these rolls. , Between the pressure roll and the metal roll.

  When a film made of polyetheretherketone resin, which is a film for a diaphragm, was obtained, the film thickness, film thickness tolerance, heat resistance and acoustic characteristics of this polyetheretherketone resin film were measured in the same manner as in Example 1. And the results are shown in Table 2.

[Comparative Example 2]
The polyether ether ketone resin used in Comparative Example 1 was changed to Vestakeep 3300G (hereinafter abbreviated as “3300G”) [product name manufactured by Daicel Evonik Co.] A band-shaped film made of polyetheretherketone resin was extruded by using a die.

  The temperatures of the single-screw extruder, the T-die, the connecting pipe connecting the single-screw extruder and the T-die, and the gear pump were the same as those in Comparative Example 1. The temperature of the molten polyetheretherketone resin was 396 ° C. when the resin temperature at the entrance of the T-die was measured. The temperature of the metal roll as the cooling roll was 210 ° C. as in Comparative Example 1.

  When a film made of a polyetheretherketone resin, which is a film for a diaphragm, was obtained, the film thickness, film thickness tolerance, heat resistance, and acoustic characteristics of the polyetheretherketone resin film were measured in the same manner as in Example 1. The results were evaluated and the results are shown in Table 2.

[Comparative Example 3]
The same as in Example 1 except that the polyetheretherketone resin used in Comparative Example 1 was changed to KetaSpire PEEK KT-851NL SP (hereinafter abbreviated as “KT-851NL SP”) (product name manufactured by Solvay Specialty Polymers). By using a single screw extruder and a T die, a belt-shaped film made of polyetheretherketone resin was extruded.

  The temperatures of the single-screw extruder, the T-die, the connecting pipe connecting the single-screw extruder and the T-die, and the gear pump were the same as those in Comparative Example 1. The temperature of the molten polyetheretherketone resin was 395 ° C. when the resin temperature at the inlet of the T-die was measured. The temperature of the metal roll as the cooling roll was changed to 200 ° C.

  When a film made of polyetheretherketone resin, which is a film for a diaphragm, was obtained, the film thickness, film thickness tolerance, heat resistance, and acoustic characteristics of this film were evaluated in the same manner as in Example 1, and the results were tabulated. 2

[Evaluation]
The film made of the thermoplastic polyimide resin in each of the examples has a glass transition point of 170 ° C. or higher, a tensile modulus at 160 ° C. of 700 N / mm ^{2 to} 2000 N / mm ² , and a specific gravity of 1.2 to 1.4. hereinafter, a tensile modulus at 23 ° C. is 1500 N / mm ² or more 2500N / mm ² or less, a loss tangent at 20 ° C. was 0.010 or more. Therefore, the film made of the thermoplastic polyimide resin in each of the examples had high heat resistance, and thus had excellent durability and also exhibited excellent acoustic characteristics. Further, the thickness tolerance of the film was within ± 10%, and no problem was found in the suitability for forming the film.

In contrast, the film made of the polyetheretherketone resin in the comparative example has a specific gravity of 1.2 or more and 1.4 or less, a tensile modulus at 23 ° C. of 1000 N / mm ² or more and 3000 N / mm ² or less, and a loss at 20 ° C. The tangent was 0.010 or more, and the film thickness tolerance was within ± 10%, and no problems were recognized in acoustic characteristics and film forming suitability. However, since the glass transition point is less than 160 ° C. and the tensile modulus at 160 ° C. is less than 700 N / mm ² , the heat resistance of the film is low, and the durability when used as a diaphragm of a speaker of a portable device. Had a problem.

  The method for manufacturing a film for a diaphragm of a speaker according to the present invention is used at least in the field of manufacturing a speaker built in a portable device or the like.

Reference Signs List 1 molding material 2 film 3 laminated intermediate 4 elastomer layer 5 primer 10 melt extrusion molding machine (extrusion molding machine)
12 Inert gas supply pipe 13 T dice (die)
17 Crimping roll (roll)
18 Cooling roll (roll)
19 Winding machine 20 Winding tube 21 Slit blade 22 Tension roll

Claims (4)

A method for producing a film for a diaphragm of a speaker in which a film is formed using a resin-containing molding material,
A molding material containing a thermoplastic polyimide resin is melt-kneaded, a film is continuously extruded from a die into a band shape using the molding material, and the extruded film is brought into contact with a roll and cooled, thereby cooling. The thickness of the film is 2 μm or more and 110 μm or less,
The film after cooling has a tensile modulus at 23 ° C. of not less than 1000 N / mm ^{2 and not} more than 3000 N / mm ^2, a glass transition point of not more than 160 ° C. after cooling, and a first change in the storage modulus of the film after cooling. The inflection point temperature is from 160 ° C to 240 ° C, the tensile modulus at 160 ° C of the cooled film is from 700 N / mm ^{2 to} 2000 N / mm ^2, and the specific gravity of the cooled film is from 1.2 to 1 0.4 or less, and the loss tangent at 20 ° C. of the film after cooling is 0.010 or more and 0.4 or less. Equipped with an extruder that melts and kneads the molding material, while feeding the molding material while supplying an inert gas to the extruder,
2. The production of a film for a diaphragm of a speaker according to claim 1, wherein the rolls are a pressure roll and a cooling roll for sandwiching the film, and at least the temperature of the cooling roll among the pressure roll and the cooling roll is adjusted to 50 ° C. or more and 240 ° C. or less. Method.   3. The method according to claim 1, wherein the cooled film is laminated and adhered to an elastomer layer having a thickness of 10 μm or more and 100 μm or less, and the film and the elastomer layer are thermoformed.   4. The method for producing a film for a speaker diaphragm according to claim 3, wherein the durometer hardness of the elastomer layer made of a silicone resin when measured with a durometer type A according to JIS K 6253 is from A10 to A90.

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