JPH01185098A - Manufacture of vitreous hard carbonaceous diaphragm having compressional construction - Google Patents

Abstract

PURPOSE:To inexpensively obtain an excellent acoustic characteristic by constructing a carbon porous material layer which is a non-dense construction in a diaphragm composed of a dense construction carbon. CONSTITUTION:A film, in which a vitreous dense construction carbon can be obtained by a baking in an inert gas atmosphere, is formed, an organic porous material film, in which a vitreous non-dense construction carbon can be obtained by the baking in the inert gas atmosphere, is formed, and the dense construction film and the film for the non-dense construction are laminate-joined. The obtained laminated film is formed in the required shape of the diaphragm. For the formed body to be demolded, contained solvent and plasticizer are volatilized by being heated in an air oven, simultaneously, a cross-linking reaction is completed, and the body can be made into a baked precursor not to be deformed even by the heating thereafter. It is heated in the inert gas atmosphere, and a baked body can be obtained. For the vitreous hard carbonaceous diaphragm having the compressional construction to be obtained in such a way, the shape at the time of forming can be maintained with a high accuracy, and simultaneously, the functional characteristic of a vitreous carbon material can be exerted to the highest degree.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of manufacturing a diaphragm for an audio device made entirely of carbon. Specifically, the present invention can be used as a diaphragm for speakers and microphones because it is lighter and more elastic than conventional diaphragm materials, has a faster sound transmission speed, and has excellent rigidity, so it can be used as a diaphragm for speakers and microphones. The present invention relates to a method for producing an all-carbon diaphragm for audio equipment, which is suitable for the digital audio era and has little deformation, low sound distortion, a wide playback range, and can produce clear sound quality.

(Prior Art) Generally, it is desirable that a diaphragm for a speaker etc. satisfy the following conditions.

(1) Low density.

(2) Young's coefficient is large.

(3) The propagation speed of longitudinal waves is high.

(4) The internal loss of vibration is appropriately large, and (5) it is stable against changes in outside air conditions and does not deform or change in quality.

(6) The manufacturing method is simple and inexpensive.

In other words, it has a wide range of sound that can be faithfully reproduced over a wide range of frequency bands, is efficient, has high rigidity to produce clear sound quality, has no distortion such as creep due to external stress, and has a low sound propagation speed. Large is required.

V-(E/ρ)1'' [However, ■: velocity of sound; E: Young's modulus; ρ: density] In order to increase the sound velocity, a material with low density and high Young's modulus is required. Paper (
Pulp), plastics and their materials as base materials, composites of glass fibers and carbon fibers, aluminum, titanium, magnesium, beryllium,
Metals such as boron, alloys of these metals, and processed materials such as nitrides, carbides, and borides were used.

However, paper (pulp), plastics, and their composite materials have a small ratio of Young's modulus to density, and therefore the sound velocity is slow. This makes it difficult to obtain clear sound quality, and it is also susceptible to external environments such as temperature and humidity, resulting in deterioration of the quality of the material and fatigue over time, resulting in deterioration of characteristics. have.

On the other hand, when metal plates such as aluminum, titanium, and magnesium are used, the speed of sound is faster than that of paper or plastic, and they have excellent performance, but they still have a small E/ρ value.
In addition, since the internal loss of vibration is small, there are disadvantages such as sharp resonance phenomena in high frequency bands and degradation of characteristics due to fatigue over time such as material creep.Beryllium and boron also have excellent physical constants. Squawkers and tweeters that use these materials for their diaphragms have a reproduction limit that extends beyond the audible frequency range, allowing them to correctly reproduce signals in the audible range without transient phenomena, resulting in natural sound quality. can be expressed. However, these materials are scarce in resources and extremely expensive, making it impractical to use conventional diaphragm manufacturing methods using roll rolling and press forming.
Since the process has to rely on vapor deposition methods that require advanced techniques such as .

(Problems to be Solved by the Invention) In view of the above-mentioned drawbacks of conventional diaphragm materials, an object of the present invention is to utilize the excellent physical properties of carbon to industrially produce a diaphragm with excellent acoustic properties. The purpose is to provide a method of manufacturing at low cost.

(Means for Solving the Problems) In order to achieve the above object, the inventors of the present application have conducted extensive research and found that thermosetting resin is used as a raw material, and after preforming it into a film shape, the diaphragm shape is He invented a method for manufacturing a glass-like hard carbon diaphragm for acoustic equipment, which is obtained by shaping the diaphragm into a diaphragm and firing it in an inert gas atmosphere, and filed a patent application (Japanese Patent Laid-Open No. 61-65596). The diaphragm according to the present invention can be produced industrially at low cost and has excellent physical properties, but as a result of intensive research to further improve the physical properties of this diaphragm, the inventor of the present invention found that the Young's modulus remained large. ,
In order to reduce the density and increase the internal loss of the diaphragm, we focused on the fact that it is beneficial to construct a carbon porous layer with a loose structure in the diaphragm made of dense carbon. By creating a carbon diaphragm in which a carbon layer and a dense structure carbon layer are integrated, a diaphragm with better acoustic characteristics than glassy hard carbon diaphragms for audio equipment has been invented.

The inventor of the present application has developed a dense carbon layer made of glassy carbon that has high hardness, high elastic modulus, high precision, and high workability, and a sparse carbon layer that is important for reducing density and increasing internal loss of vibration. We ingeniously devised ways to form composite carbon into any desired shape.

Next, a method of manufacturing a glassy hard carbonaceous diaphragm having a dense and dense structure according to the present invention will be explained.

First, a film containing glassy dense carbon is produced by firing in an inert gas atmosphere. This is a film made of thermosetting resin. The thermosetting resins used here include furan resin, phenol resin, xylene resin, epoxy resin, and bismaleimide resin, but they have a high degree of freedom in shaping and do not require complicated pretreatment during carbonization. Since this is not necessary, furan resins such as furfuryl alcohol/furfural type, furfural/phenol type, furfural/elia type, resol type, novolac type phenol resins, or mixed resins thereof are preferred.

Next, by firing in an inert gas atmosphere, a perforated porous film from which glassy loosely structured carbon is obtained is produced. This is an organic material porous film made of organic material particles with point adhesion between them.

The organic material particles used here are particles of chlorinated vinyl, polyacrylonitrile, polydivinyl alcohol, polyphenylene ether, polydivinylbenzene, etc., and monomers or initial condensates such as furan, phenol, bisyareimide/triazine, etc., to the extent that they can be thermally deformed. Particles that have been hardened to a pulp, gum tragacanth, gum arabic, I!
Natural polymer particles having fused polycyclic aromatics such as m in the basic structure of the molecule, petroleum asphalt, coal tar pinch,
These particles are one type or a mixture of two or more types of particles obtained by heat-treating carbonized pitch such as a synthetic resin at 300 to 500°C and removing low-molecular compounds with a solvent.

Next, the dense structure film and the sparse structure film are laminated and bonded. In this method, a laminated integrated film is obtained by thermal fusion or adhesion using a liquid composition that leaves a high carbon residue by firing in an inert gas atmosphere. The liquid composition here is composed of a combination of thermoplastic resins such as polyvinyl chloride and polyacrylonitrile, thermosetting resins such as phenol and furan, natural polymeric substances such as gum tragacanth, pitches, etc., and is in a liquid state at room temperature. If this does not occur, use an initial condensate of the resin or one dissolved in a solvent. The obtained laminated film is molded into the desired shape of a diaphragm by hot press molding, vacuum molding, blow molding, or the like.

The demolded product is heated in an air oven to volatilize the solvent and plasticizer contained therein, and at the same time, completes the crosslinking reaction, resulting in a fired precursor that does not deform even with subsequent heating. This is heated in an inert gas atmosphere such as nitrogen gas or argon at a temperature of 500°C or higher, preferably 1000°C or higher.
Heat to 1500'C, 2500' if necessary
A fired body is obtained by heating to a temperature higher than c.

The glassy hard carbonaceous diaphragm having the dense and dense structure thus obtained maintains the shape at the time of shaping with high precision and exhibits the functional characteristics of the glassy carbon material to the highest degree.

(Examples) The present invention will be explained in detail below using Examples, but the present invention is not limited by the Examples.

Real AI (+lI 1 Furfuryl alcohol/Furfural initial N compound (VF302 manufactured by Hitachi Chemical) 100% by weight as a curing agent P-) Luenesulfone 950% methanol solution 4
After adding % by weight and thoroughly stirring, a 40 μm thick plastic dense structured film was prepared using a coater equipped with a doctor blade. On the other hand, chlorinated vinyl chloride resin powder (manufactured by Nippon Carbide) was placed in a pie-break container.
A porous film having a thickness of 60 μm formed by point fusion was obtained by holding the film in a heating oven at 180° C. using the following method.

Next, a dense structure film, a porous film, and a dense structure film were laminated in this order to obtain a laminated film. At this time, furfuryl alcohol/furfural initial condensate was used as a bonding agent. The obtained laminated film was shaped into a dome shape with a diameter of 50 mm using a vacuum forming machine, heated to 180° C. in a mold, precured, and then demolded. Next, this molded body was heat-treated to 250°C in an air oven, and after being completely cured, it was fired to 1000°C in a firing furnace in a nitrogen gas atmosphere to obtain a glass-like hard carbonaceous diaphragm having a dense and dense structure. . The obtained diaphragm had a film thickness of 70 μm and a diameter of 40 mm. Physical properties include density 1.10g/cm, Young's modulus 74GPa, sound velocity 8200m/sec, and internal loss Jan δ.
It was 0.06.

Soil Comparison - Physical properties of the glassy hard carbonaceous diaphragm that was created and fired by creating and firing the diaphragm consisting only of the dense structure film in Example 1 were: density 1.40 g/cm3, Young's modulus 75 GPa, and sound velocity 73.
00 m/sec, and the internal loss tan δ was 0.03.

From Example 1 and Comparative Example 1, it was found that the glass-like hard carbonaceous diaphragm having a loose and dense structure with a porous layer inside had better physical properties.

Disaster treatment 1 Novolac phenolic resin (-Gunei Chemical Industry PS-
A mixture of 137,085% by weight and 15% by weight of PG8-450,000 was put into an extrusion molding machine using a T-type die to produce a dense structure film having plasticity and a film thickness of 400 μm. On the other hand, crushed purified tragacanth gum powder 9
After putting 6% by weight and 4% by weight of purified water into a Henschel mixer and dispersing and mixing, put the wet powder into a flat container using a pie breaker, and after evaporating the water in a 110℃ oven, it was heated to 180℃.
"C" was heated in an oven to obtain a porous film with a thickness of 600 μm.Next, a dense structure film, a porous film, and a dense structure film were laminated in this order to obtain a laminated film.Here, the same as in Example 1 was used as a bonding agent. A liquid composition was used.The obtained laminated film was formed into a dome shape with a diameter of 35 cm using a vacuum forming machine, heated to 180° C. in a mold, cured, and then demolded.

Next, after heat-treating this molded body to 230"c,
It was fired to 100° C. in a firing furnace in a nitrogen gas atmosphere to obtain a glassy hard carbonaceous diaphragm having a dense and dense structure.

The obtained diaphragm has a film thickness of 1000 μm and a diameter of 26 cI11.
Met. Also, the physical properties are density 1.0'9 g/am
3. Young's modulus was 64 GPa, sound velocity was 7400 m/sec, and internal loss JAN was 60.08.

Comparison - Also, the physical properties of the glass-like hard carbon diaphragm obtained by preparing and firing the diaphragm made of only a dense structure film in Example 2 are as follows.
The density was 1.37 g/cm3, the Young's modulus was 62 GPa, the sound velocity was 6700 m/sec, and the internal loss tan δ was 0604.

In both Example 2 and Comparative Example 2, it was found that the glass-like hard carbonaceous diaphragm having a dense structure with a porous layer inside had better physical properties.

Claims (5)

[Claims] (1) A film made of a thermosetting resin that produces glassy dense carbon with high hardness and impermeability by firing in an inert gas atmosphere, and a glassy loose carbon that is produced by firing in an inert gas atmosphere. A composite film having a desired thickness obtained by laminating and integrating the obtained organic porous film is formed into a designed diaphragm shape, and then treated in heated air to proceed with a curing reaction and exhibit thermal deformation. A method for manufacturing a glass-like hard carbonaceous diaphragm having a dense and dense structure, which comprises curing the diaphragm in an inert gas atmosphere. (2) The thermosetting resin includes furfuryl alcohol resin,
The non-condensing material according to item 1 selected from furan resins such as furfuryl alcohol/furfural co-condensed resins, furfural/phenol co-condensed resins, phenolic resins such as resol-based and novolak-based resins, xylene resins, toluene resins, resorcinol resins, etc. A method for manufacturing a glass-like hard carbonaceous diaphragm having a structure. (3) The organic porous body is a thermosetting resin such as particles of thermoplastic resin such as chlorinated vinyl chloride, polyacrylonitrile, polyvinyl alcohol, polyphenylene ether, and polydivinylbenzene, furan resin, phenol resin, and bismaleimide/triazine resin. Particles obtained by pulverizing resin monomers or initial condensates cured to the extent that they can be thermally deformed, natural polymer particles having a condensed polycyclic aromatic group such as gum tragacanth, gum arabic, or saccharides in the basic structure of the molecule, or Synthetic polymer particles with a diameter or maximum side of 2 mm that have a fused polycyclic aromatic group in the basic structure of the molecule that is not included in the above.
A mixture of one or two or more particles having the following properties and in which the diameter or maximum side of 90% or more of the particles is 30 μm or more is melted by heating or melted by a solvent to melt the surface layer and cause point adhesion. 2. The method for manufacturing a glass-like hard carbonaceous diaphragm having a dense and dense structure according to item 1, which comprises performing an infusible treatment after bonding the particles. (4) The lamination and integration process consists of adhering to one or a mixture of two or more organic polymeric substances that leave a high carbon residue using a liquid composition to which a solvent is added, if necessary. A method for manufacturing a glassy hard carbonaceous diaphragm having a dense and dense structure according to item 1. (5) The method for manufacturing a glassy hard carbonaceous diaphragm having a dense and dense structure according to item 1, wherein the firing is performed at a temperature of 500° C. or higher.