JP3025542B2 - Diaphragm for carbonaceous acoustic equipment and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diaphragm for carbonaceous acoustic equipment and a method for manufacturing the same. More specifically, as a diaphragm for a speaker and a microphone, a carbonaceous acoustic device having high hardness, high strength, a high elastic modulus, and light weight and excellent acoustic characteristics as compared with a conventional diaphragm material. And a method of manufacturing the same.

[0002]

2. Description of the Related Art Generally, it is desirable that a diaphragm such as a speaker satisfy the following conditions. Low density. High Young's modulus. Longitudinal wave propagation speed is high. Moderately large internal loss of vibration.
It is stable against changes in outside air conditions, and has no deformation or deterioration. The manufacturing method is simple and inexpensive.

That is, in order to reproduce a wide frequency band faithfully, to have good energy conversion efficiency of electric sound and to express clear sound quality, it is required to have high rigidity and light weight without distortion such as creep due to external stress. From the equation of V = (E / ρ) (where V: sound velocity E: Young's coefficient ρ = density), a material having a small density and a high Young's modulus is required to increase the sound velocity.

Conventional diaphragm materials include paper (pulp), plastic, aluminum, titanium, beryllium, boron and the like as a base material, which are further combined with glass fibers or carbon fibers, or metal alloys. What has been processed into metal carbide, metal boride and the like has been used.

However, paper, plastic, and their materials have a small ratio of Young's modulus to density and low rigidity, so that split vibration occurs in a specific mode, and the frequency characteristics particularly in a high frequency band are remarkably deteriorated. It is difficult to obtain clear sound quality, and furthermore, it is easily affected by external environment such as temperature and humidity, and has the disadvantages that the quality of the material is deteriorated and the fatigue with time occurs to deteriorate the characteristics. . Also,
Carbon fiber reinforced plastic (CFRP) is a composite material that has high strength, high elasticity, and excellent properties such as high sound propagation speed in the fiber orientation direction. And physical characteristics in other directions are significantly different.

On the other hand, when a metal plate made of aluminum, titanium, or the like is used, the sound speed is high and excellent properties are obtained.
There is a disadvantage that the internal damage of the diaphragm is small, a sharp resonance phenomenon occurs in a high frequency region, and fatigue occurs with time such as creep of a material, thereby deteriorating characteristics. In addition, boron, beryllium and their nitrides, carbides, borides, etc. are materials having excellent physical properties. Because of the extension, the high-frequency distortion exceeds the audible frequency band, so that a signal in the audible frequency band can be faithfully reproduced and natural sound quality can be exhibited.

[0007] However, these materials are extremely expensive and extremely difficult to process industrially. Therefore, the conventional method of manufacturing a diaphragm by roll rolling and press molding is not practical. V. D. And P.A. V. D. Since it has to rely on the evaporation method that requires advanced technology such as
Processing costs are extremely high, and there are drawbacks such as difficulty in manufacturing a large speaker for reproducing low-frequency sound.

As is well known, carbon has an extremely wide range of physical and chemical properties, from crystalline carbon of diamond and graphite to amorphous carbon such as carbon black and charcoal. The present inventors have conducted intensive studies to design and combine these carbon materials according to required functions so as to express various desired functional characteristics.

First, the theoretical elastic modulus of graphite is 1020.
Focusing on the fact that GPa has an extremely high modulus and a low density compared to the elastic modulus of other materials and that glassy carbon has higher physical properties than resins and metallic materials, A method of manufacturing a carbonaceous diaphragm composed entirely of graphite / carbon composite material having excellent physical properties by incorporation of carbon powder such as natural graphite having an elastic modulus was invented, and a patent application was filed (Japanese Patent Application Laid-open No. Sho 60/1985). −121895
No.).

Furthermore, attention is paid to the fact that vitreous hard carbon made of only resin as a raw material has high precision and free workability, and glass that can be mass-produced industrially and can be manufactured at low cost. Invented a method for manufacturing a rigid carbonaceous acoustic diaphragm, and filed a patent application (JP-A-61-65596). However, a carbonaceous diaphragm made of a graphite / carbon composite material has extremely excellent physical properties, but has a drawback that it is somewhat poor in shapeability and lacks industrial mass productivity. Although a carbonaceous diaphragm made of only hard carbon can be easily mass-produced industrially, it has a drawback that physical properties are inferior to those of a carbonaceous diaphragm made of a graphite / carbon composite material. .

[0011]

SUMMARY OF THE INVENTION In view of the above-mentioned drawbacks of the conventional diaphragm material, the object of the present invention is to take advantage of the excellent physical properties of carbon and to be independent of external environments such as temperature and humidity. Also, we have provided a diaphragm that can faithfully reproduce a wide frequency range from the low frequency range to the high frequency range without causing fatigue over time such as creep of the material, and can express clear sound quality. An object of the present invention is to provide an inexpensive manufacturing method.

[0012]

Means for Solving the Problems The inventors of the present application have conducted further intensive studies to obtain a method of manufacturing a carbonaceous diaphragm which can be easily mass-produced industrially and has excellent physical characteristics. As a result, on the surface of the vibrating plate base made of vitreous hard carbon, graphite with crystals with high modulus of elasticity developed and oriented in the plane direction to form a carbonaceous vibrator made of vitreous hard carbon. It has better physical properties than plate.
The present inventors have completed a diaphragm for carbonaceous acoustic equipment of the present invention, which has higher mass productivity than a carbon diaphragm made of a carbon composite material, and a method of manufacturing the same.

More specifically, the present invention provides (1) a carbonaceous acoustic material in which graphite having a crystal having a high elastic modulus is oriented in a plane direction and fixedly formed on the surface of a diaphragm base material made of glassy hard carbon. It is a diaphragm for equipment,

(2) A monomer and / or precondensate of a thermosetting resin is shaped into a diaphragm, and a mixture of highly crystalline graphite having an average particle size of 1.0 to 200 μm and a thermosetting resin is formed on the surface thereof. Is applied or cast in a mold, and a curing reaction is allowed to proceed to obtain a formed form. After the formed form is subjected to a carbon precursor treatment, the temperature is controlled in an inert atmosphere at a rate of 900 ° C.
A method for producing a diaphragm for carbonaceous acoustic equipment, characterized in that the carbonized material is heated and carbonized at a temperature of at least ℃.

(3) A film of a monomer and / or a precondensate of a thermosetting resin, a highly crystalline graphite having an average particle size of 1.0 to 200 μm, and a thermosetting resin on a back sheet having a release agent on the surface. A composite film with a film of the mixture is prepared and pre-cured to obtain a pre-formed sheet having still soft plasticity, the back sheet is removed, the pre-formed sheet is shaped into a diaphragm, and the curing reaction proceeds. To obtain the generated form,
Manufacturing a diaphragm for a carbonaceous acoustic device, wherein the formed body is subjected to a carbon precursor treatment and then heated to 900 ° C. or more and carbonized in an inert atmosphere while controlling a heating rate. Is the way.

In the present invention, a vibrating plate base made of glassy hard carbon is prepared using only a thermosetting resin as a raw material. This means that by using a thermosetting resin as a raw material, the degree of freedom during shaping can be increased, molding can be performed extremely easily, firing distortion and the like can be easily eliminated, and after firing. Density of glassy hard carbon is 1.35 ~
1.50 g / cm ^{3, which} is extremely small, making it possible to reduce the weight of the diaphragm, making it possible to use many shaping means industrially, and simplifying the process without complicated pretreatment required for carbonization. Is possible.

On the other hand, the graphite layer on the surface of the diaphragm base material is prepared by using graphite powder and a thermosetting resin binding the graphite powder as raw materials. This is because it is possible to obtain a diaphragm exhibiting high physical properties by using graphite powder with extremely high theoretical elastic modulus compared to other materials, and to mix graphite by using thermosetting resin. This is because the degree of freedom during shaping can be maintained, molding can be easily performed, and graphite can be oriented.

Next, a method for manufacturing a diaphragm for a carbonaceous acoustic device according to the present invention will be specifically described. In the present invention, as a raw material for the diaphragm base material, a predetermined amount of a curing agent is added to a thermosetting resin as needed, and dispersion is performed using a high-speed agitator or the like, and then bubbles are removed by a vacuum degassing apparatus. Is used.

On the other hand, as a raw material for the graphite layer on the surface of the diaphragm substrate, graphite powder, a thermosetting resin, a high-speed agitator or a three-roll mill are used, and they are sufficiently kneaded and dispersed. Is added, and the mixture is dispersed again. Then, a mixture obtained by removing bubbles by a vacuum degassing apparatus is used.

Here, usable thermosetting resins include phenolic resins, furan resins, xylene resins, toluene resins, copna resins, and the like, and particularly preferred are monomers and / or precondensates thereof, which flow when heated. At the same time, a material which causes intermolecular cross-linking, is three-dimensionally cured, and has a high carbon residue yield without a special carbon precursor treatment is used.

As the highly crystalline graphite, crystalline natural graphite, quiche graphite, highly oriented gas-phase decomposed graphite, graphite whisker and the like are preferable.
２００200 μm is used.

In the present invention, as a method of forming and shaping into a diaphragm shape, there are a hand lay-up method, a spray-up method, a cast molding method, which is a usual plastic shaping method.
A simple and rapid molding means such as an injection molding method, a vacuum molding method, and a blow molding method is used alone or in combination.

At this time, when a hand lay-up method, a spray-up method, a cast molding method, an injection molding method, or the like is used as a method for forming and shaping the diaphragm, first, a vitreous hard carbon layer portion is formed. The raw material liquid obtained for the part to be formed is applied on the surface of the mold or poured into the mold, and the curing reaction proceeds at room temperature or under heating to solidify, and then obtained for the part to be the graphite layer part from above. The raw material liquid is applied to the surface of the mold or poured into the mold, and after the curing reaction is sufficiently advanced at room temperature or under heating, the molded product is obtained by releasing the mold.

When a vacuum forming method, a blow molding method, or the like is used, a glassy hard carbon layer is first obtained by using a coater or a calender roll on a back sheet having a release agent on its surface. A film consisting of a layer having a desired thickness composed of the raw material liquid and a layer having a desired thickness composed of the raw material liquid obtained for the graphite layer portion is preliminarily formed, and then the film is still cured. Without plasticity (B
In step (stage), the back sheet is removed, and a desired diaphragm shape is formed using each forming method. At this time,
The plasticity can be increased by appropriately heating or the curing reaction can be advanced. After the material is sufficiently cured, it is released from the mold and the formed product is taken out.

Next, the obtained shaped body is subjected to a carbon precursor treatment in a room temperature or heated air oven, and then housed in a firing vessel and placed in an inert atmosphere such as nitrogen gas or argon gas. To control the heating rate
After heating to ℃ or more to complete the carbonization, the natural graphite is allowed to cool and the firing is completed, so that the graphite with a high modulus of elasticity developed on the surface of the diaphragm base material made of vitreous hard carbon. Thus, a diaphragm for carbonaceous acoustic equipment which is oriented and formed in the plane direction can be obtained. If necessary, further heat treatment is performed from 2500 ° C. to 3000 ° C. in a vacuum or in an argon gas phase to make the whole graphite.

[0026]

The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples. (Example 1) As a raw material liquid for a glassy hard carbon layer portion, 100% by weight of an initial condensate of furfuryl alcohol / furfural resin (VF-302 manufactured by Hitachi Chemical Co., Ltd.) and p- Toluenesulfonic acid (3% by weight) and methanol solution (3% by weight) were added, and a degassing operation was performed under reduced pressure while sufficiently stirring at room temperature using a high-speed homomixer.

As the raw material liquid for the graphite layer, 85% by weight of an initial condensate of furfuryl alcohol / furfural resin (VF-302 manufactured by Hitachi Chemical Co., Ltd.), natural scaly graphite with well-developed crystals (average particle size) 5 μm) 15% by weight
To a mixture sufficiently kneaded and dispersed using a three-roll mill, 5% by weight of p-toluenesulfonic acid and 5% by weight of a methanol solution are added as curing agents, and defoaming under reduced pressure with sufficient stirring at room temperature using a high-speed homomixer. Prepared one after operation.

Next, using a coater having a doctor blade part capable of multi-layer coating, a 100 μm thick film made of a raw material liquid for a glassy hard carbon layer part and graphite were placed on a back sheet provided with a release film on the surface. A composite film with a film having a thickness of 15 μm made of the raw material liquid for the layer portion was prepared and pre-cured to obtain a preformed sheet having sufficiently flexible plasticity (B-stage state).

Next, the back sheet of the obtained film was removed, formed into a dome shape by a vacuum forming machine using a dome-shaped forming die having a diameter of 30 mmφ, and cured by heating with hot air at 80 ° C. The molded form was obtained.

The molded body is further subjected to a post-curing treatment in an air oven at 150 ° C. for 5 hours, and then placed in a baking case and heated in a nitrogen gas atmosphere furnace to 500 ° C. at a rate of 15 ° C./hour. 50 ° C / 1000 ° C to 50 ° C /
Heating was performed at the temperature rising rate at the time, and the temperature was maintained at 1000 ° C. for 3 hours, followed by natural cooling to complete the firing.

A vibrating plate for a carbonaceous acoustic device in which graphite obtained by development of crystals having a high modulus of elasticity is oriented in the plane direction on the surface of the vibrating plate base material made of vitreous hard carbon thus obtained. Has a diameter of 24 mm, a thickness of 55 μm, and a weight of 30
mg, Young's modulus 102 GPa, sound velocity 8.3 km / sec, density 1.46 g / cm ³ , and internal loss tan δ of 0.01.

(Example 2) A resol type phenol resin (RM-300A manufactured by Asahi Organic Materials Co., Ltd.) was prepared as a raw material liquid for the glassy hard carbon layer portion, and a transfer type injection molding machine was used by using this. As a result, a dome-shaped living body having a diameter of 60 mmφ was obtained.

Next, as a raw material liquid for the graphite layer portion, a resol type phenol resin (RM-30 manufactured by Asahi Organic Materials Co., Ltd.) was used.
0A) 85% by weight, 15% by weight of natural crystalline graphite (average particle size: 5 μm) with well-developed crystals was subjected to defoaming under reduced pressure with sufficient stirring at room temperature using a high-speed homomixer.

Then, the obtained shaped body was held on a jig capable of planetary movement, and an even layer made of the raw material liquid for the graphite layer portion was constructed on the surface thereof by a spray-up method.

Thereafter, the formed body is further subjected to a post-curing treatment in an air oven at 180 ° C. for 5 hours, and then placed in a baking case to 15 ° C./500° C. in a nitrogen gas atmosphere furnace.
Heating at the heating rate of
Heating was carried out at a heating rate of 0 ° C./hour, the temperature was maintained at 1000 ° C. for 3 hours, and then the product was naturally cooled to complete firing.

The thus obtained diaphragm for carbonaceous acoustic equipment having a vibrating plate made of vitreous hard carbon and having a graphite layer on which a crystal having a high elastic modulus has been formed is formed on the surface of the diaphragm base material. , Thickness 105 μm, weight 600 mg, Young's modulus 91 GPa, sound velocity 8.0 km / sec, density 1.41
g / cm ³ and an internal loss tan δ of 0.015 in all directions.

[0037]

According to the diaphragm for a carbonaceous acoustic device of the present invention and the method for producing the same, a highly crystalline graphite powder layer exhibiting a high elastic modulus is oriented and constructed on the surface of the substrate of the diaphragm. A diaphragm having excellent physical properties can be obtained. Since a thermosetting resin is used as a main raw material for forming the diaphragm, many shaping means can be used industrially, and the industrial mass productivity is excellent. Since a thermosetting resin is used as the main raw material, complicated pretreatment is not required for carbonization, the process can be simplified, firing distortion and the like can be easily eliminated, and quality control is easy.

Therefore, the diaphragm of the present invention makes it possible to exhibit the performance of a digital audio device having clear sound quality and a wide dynamic range with high performance. In addition, the manufacturing method can be manufactured at a very low cost by a simple process, so that the industrial effect is great.

Claims (3)

(57) [Claims] 1. A diaphragm for carbonaceous acoustic equipment in which graphite having a crystal having high elasticity is oriented in a plane direction and fixedly formed on a surface of a diaphragm base material made of glassy hard carbon. 2. A monomer and / or precondensate of a thermosetting resin is shaped into a vibrating plate, and the surface thereof has an average particle size of 1.
After a mixture of 0 to 200 μm of highly crystalline graphite and a thermosetting resin is applied or cast in a mold, a curing reaction is allowed to proceed to obtain a formed product, and the formed product is subjected to a carbon precursor treatment. ,
A method for producing a diaphragm for carbonaceous acoustic equipment, comprising heating to 900 ° C. or more and carbonizing while controlling a temperature rising rate in an inert atmosphere. 3. A film of a monomer and / or precondensate of a thermosetting resin, a highly crystalline graphite having an average particle size of 1.0 to 200 μm, and a thermosetting resin on a back sheet having a release agent on its surface. Create a composite film with the mixture film, pre-cured, obtain a pre-formed sheet with still soft plasticity, remove the back sheet, shape the pre-formed sheet into a diaphragm shape, and proceed with the curing reaction A carbonaceous material obtained by subjecting the green compact to a carbon precursor treatment by subjecting the green compact to a carbon precursor treatment and then heating the carbon to a temperature of 900 ° C. or more in an inert atmosphere while controlling the temperature rising rate. Manufacturing method of diaphragm for equipment.