JP2890789B2 - Manufacturing method of diaphragm - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbonaceous diaphragm used for audio equipment and the like, and more particularly to a method for manufacturing a diaphragm having characteristics optimal for a speaker, a microphone, and the like. .

2. Description of the Related Art In recent years, audio equipment has almost been digitized, and the quality of sound has been dramatically improved. Since then, the required performance of a speaker for provisional vibration has become increasingly severe. Such a diaphragm is required to have a small deformation due to external force and a small sound distortion, and to have a wide reproduction sound range and a clear sound quality. Excellent things are required. To summarize this as a condition for specific physical property values, the Young's modulus (E) is large.

The density (ρ) is small.

High sound velocity (sound propagation velocity V).

Appropriate internal loss of vibration (tanδ).

And so on. Where V, E, and ρ There is a relationship. It goes without saying that, in addition to these conditions, ease of processing, solderability, rust resistance, stability against external conditions such as heat and humidity are also important.

Conventionally, as such a diaphragm material, paper, plastic, aluminum, titanium, magnesium, beryllium, boron, silica and the like have been used. These have been used in various forms, either alone or as a composite with glass fiber or carbon fiber, or as a metal alloy. However, paper and plastic do not have sufficient properties such as Young's modulus, density, and sound velocity as a diaphragm, and the frequency characteristics particularly in the high frequency band are extremely poor, and these materials are clearly used as diaphragms such as tweeters. It was difficult to obtain a good sound quality.
Although aluminum, magnesium, titanium and the like have a very high sound velocity, the internal loss of vibration is small, so that a high-frequency resonance phenomenon occurs, which also has insufficient characteristics as a high-frequency diaphragm. Was. On the other hand, boron, beryllium, and the like have excellent physical property values as compared with the above-mentioned materials, and can exhibit good sound quality as a diaphragm. However, boron and beryllium have the disadvantage that they are extremely expensive and have extremely poor workability.

A diaphragm using a carbon material has been developed with the aim of overcoming the above-mentioned drawbacks of the conventional diaphragm material, having excellent high-frequency characteristics, and reproducing a high-quality tone. This utilizes the excellent physical properties of carbon and graphite (graphite) and uses it as a diaphragm. Such techniques include: (1) a composite type comprising graphite powder and a polymer resin.

(2) A graphite / carbon composite type in which a composite material composed of graphite powder and a polymer resin is further sintered.

(3) A method of carbonizing and graphitizing a polymer film alone.

and so on.

Among these, as a representative of the method (1),
There is a diaphragm in which a polyvinyl chloride resin is used as a matrix and a graphite powder is combined with the matrix. Although this is known as a diaphragm having excellent properties, its humidity and temperature characteristics are inferior, and its vibration characteristics are significantly deteriorated at 30 ° C. or higher.

As the method (2), a graphite powder is mixed with a crude oil cracked pitch liquid crystal component and then heat-treated and carbonized, or a thermosetting resin monomer or an initial material is used as a raw material of a carbonized binder for binding the graphite powder to the graphite powder. There is known a method of carbonizing by heat treatment using a thermoplastic resin having a functional group which decomposes upon heating with a polymer and reacts with each other to crosslink and cure. These methods have been developed for the purpose of increasing the carbon yield as an organic material to prevent shrinkage and deformation during heat treatment, and can provide a diaphragm having excellent characteristics. However, these are extremely disadvantageous for industrial mass production due to the complicated manufacturing process. Furthermore, although the diaphragm obtained by this method has extremely excellent characteristics not found in the past,
Its properties are slightly inferior to beryllium, which is currently said to be the best, and the theoretical elastic modulus of graphite single crystals
That was far below 1020 GPa.

As the method (3), several polymer films have been studied. However, since all of them are non-graphitizable materials, the properties as expected at first cannot be obtained, and the carbon yield of the plastic material used is low, so that the dimensional shrinkage during heat treatment is large. There is a drawback that cracks and the like often occur.

Therefore, the present inventors have repeatedly studied the non-graphitizable material by focusing on a polymer material that is an easily graphitizable material.
Polyoxadiazole, polybenzothiazole, polybenzobisthiazole, polybenzoxazole, polybenzobisoxazole, aromatic polyimide, aromatic polyamide, polyphenylene benzoimidazole, polyphenylene benzobisimidazole having a thickness of μm or less When a polymer film of, polythiazole, and polyparaphenylene vinylene is heat-treated at a specific temperature, it is possible to obtain graphite having a higher graphitization ratio more easily than any conventionally known polymer material. confirmed. As a result, it has become clear that carbonaceous and graphite-based diaphragms having excellent properties can be obtained and that they can be manufactured in a short time.

Problems to be Solved by the Invention However, a method of obtaining a carbonaceous and graphite-based diaphragm using the special polymer film described above is an easy and very excellent method. As a result of the examination, it became clear that there were the following problems.

The first problem is distortion caused by heat treatment of the polymer film or unevenness of the surface. This distortion and surface non-uniformity not only degrade the excellent properties obtained by the heat treatment, but also impair the appearance. In addition, when the distortion becomes large, the surface of the diaphragm foams, and in some cases, it is broken.

The second problem is that the heat treatment of polymer film
Since a high temperature of 1600 ° C. or more, more preferably 2500 ° C. or more, is required, the price of the diaphragm becomes high.

The present invention solves such problems of the conventional diaphragm, and is very simple and excellent in mass productivity, and furthermore, has a carbonaceous and graphite material having characteristics superior to any conventional diaphragm. It is an object of the present invention to provide an inexpensive method for manufacturing a diaphragm.

Means for Solving the Problems In order to achieve the above object, a method of manufacturing a diaphragm of the present invention is a method of laminating a plurality of polymer films, these are heated at a temperature of 1600 ° C. or more in a vacuum or an inert gas. the pressure of 10 kg / cm ² and heat treated from the application Shinano from 0.1 kg / cm ² only to the extent, then, is obtained so as to obtain a diaphragm separating the plurality of polymer film one by one.

Action According to the above-described production method, it becomes possible to produce a diaphragm made of a large amount of polymer film having excellent properties at one time, and therefore, it becomes possible to produce a very inexpensive production compared to the conventional production method. is there.

Examples Hereinafter, examples of the present invention will be described in detail.

The present inventors, for the purpose of obtaining an ideal carbonaceous and graphite-based diaphragm, laminated a plurality of polymer films,
The carbonization and graphitization were attempted. As a result, 1600 ° C
By applying pressure only in the above temperature range, it has been found that peeling can be performed one by one at room temperature.
It was also found that the pressure applied at this time was closely related to the number and thickness of the polymer films laminated.

Table 1 shows that, as an example, a plurality of polymer films made of polypyromellitimide having a thickness of 50 μm are laminated, and these are heat-treated at 2900 ° C. while applying pressure only at 2000 ° C. or higher, and the pressure is changed. It shows the sound speed value when the sound is turned on.

As is evident from Table 1, the optimum pressure value increases as the number of polymer film layers increases. The optimum pressure when the number of laminated polymer films was 500 was 200 kg / cm ² , and the optimum pressure was 200 kg / cm ² even when the number of polymer films was increased thereafter. On the other hand, when the number of sheets is one, the optimum pressure is 0.1 kg / cm ² , and therefore, it has been found that this optimum pressure has a specific range.

Table 2 shows an example of laminating 10 polymer films made of polypyromellitimide of various thicknesses.
It shows the sound velocity value when heat treatment is performed at 2900 ° C. while applying pressure only at 1800 ° C. or higher.

As is apparent from Table 2, the optimum pressure value increases as the thickness of the polymer film increases.
Further, it can be seen that the sound velocity characteristics are improved as the thickness of the polymer film as the raw material is reduced. The thinner the polymer film as a raw material, the better the properties are. However, in consideration of handleability, strength as a diaphragm, and durability, the thickness is preferably 12.5 to 75 μm.

The polymer film used in the present invention is 400 μm
Polyoxadiazole, polybenzothiazole, polybenzobisthiazole, polybenzoxazole, polybenzobisoxazole, aromatic polyimide, aromatic polyamide, polyphenylene benzoimidazole, polyphenylene benzobisimidazole having the following thickness: It is selected from polythiazole and polyparaphenylenevinylene. Here, various aromatic polyimides are polyimides represented by the following general formula.

Where R ₁ is R ₂ It is.

The various aromatic polyamides are polyamides represented by the following general formula.

Where R ₃ is R ₄ It is.

Hereinafter, the present invention will be described by specific examples,
It goes without saying that the present invention is not limited to these.

(Example 1) A laminate of 100 polyimide films (trade name: Kapton H film) manufactured by Dubon Co. having a thickness of 25 µm is sandwiched between graphite plates, and in a nitrogen gas,
The temperature was raised at a rate of 5 ° C. per minute, and heat treatment was performed at 1000 ° C. for 1 hour. The heat-treated film thus obtained is sandwiched between graphite substrates, and is heated at a rate of 10 ° C./min.
And heat at 3000 ° C. for 1 hour, every minute
The temperature was lowered at a rate of 20 ° C. At that time, only at 2500 ℃ or higher
A pressure of kg / cm ² was applied. After cooling to room temperature, the samples were taken out, 100 sheets were punched at a time to a diameter of 27 mm, and peeled off one by one. Its characteristics are sound speed 17.8km / sec,
The internal loss was 0.17.

Example 2 Ten polyimide films (Kapton H film, manufactured by DuPont) having a thickness of 75 μm were cut to a diameter of 90 mm, and the same heat treatment as in Example 1 was performed at a pressure of 1 kg / cm ² . However, wrinkles are seen in various places on the surface, and the sound velocity value is
The value was as low as 3 km / sec. Therefore, the pressure is 10kg / cm
^When the same heat treatment was performed in place of 2, the surface properties were remarkably improved, and the sound speed was 15.4 km / sec.

In the above embodiment, the heat treatment is performed in an inert gas such as a nitrogen gas or an argon gas. However, the heat treatment may be performed in a vacuum.

Advantages of the Invention As is clear from the description of the above embodiment, the method for manufacturing a diaphragm according to the present invention comprises stacking a plurality of polymer films, and lining them in a vacuum or in an inert gas at a temperature range of 1600 ° C. or more. the pressure of 10 kg / cm ² while heat treatment applied from 0.1 kg / cm ² only, then, since to obtain a diaphragm separating the plurality of polymer film one by one, traditional method A diaphragm made of a polymer film with properties far superior to those made by a diaphragm can be mass-produced at a time, and it can be mass-produced at a low cost. The diaphragm obtained by this manufacturing method is optimal for audio equipment such as a speaker and a microphone.

────────────────────────────────────────────────── ─── Continuing on the front page (72) Mutsumi Murakami, Inventor 3-10-1, Higashi-Mita, Tama-ku, Kawasaki, Kanagawa Prefecture Inside Matsushita Giken Co., Ltd. (72) Inventor Kazuhiro Watanabe 3 Higashi-Mita, Tama-ku, Kawasaki-shi, Kanagawa No. 10-1 Matsushita Giken Co., Ltd. (58) Field surveyed (Int. Cl. ⁶ , DB name) H04R 7/00 H04R 31/00

Claims (2)

(57) [Claims] 1. A stacking a plurality of polymer films, a heat treatment while applying a pressure from 0.1 kg / cm ² for 10 kg / cm ² only these in a temperature range above 1600 ° C. In or in an inert gas vacuo Then, a diaphragm is obtained by peeling a plurality of polymer films one by one to obtain a diaphragm. 2. A polymer film having a thickness of 400 μm or less, such as polyoxadiazole, polybenzothiazole,
Polybenzobisthiazole, polybenzoxazole,
2. The vibration according to claim 1, wherein the vibration is at least one selected from polybenzobisoxazole, aromatic polyimide, aromatic polyamide, polyphenylene benzoimidazole, polyphenylene benzobisimidazole, polythiazole, and polyparaphenylene vinylene. Plate manufacturing method.