JPH0475717B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvement of a diaphragm for an electroacoustic transducer, and more particularly to a diaphragm using an inorganic scale material.

Conventionally, various types of diaphragms made of inorganic scale material and thermosetting resin have been devised and put into practical use.

The reason for this is that the diaphragm has a higher Young's modulus and a larger specific modulus of elasticity than conventional diaphragms made of paper pulp or synthetic resin, for example.
Furthermore, it has excellent moisture resistance and flame retardancy.

Conventionally, such diaphragms mainly made of inorganic scale material are produced by (1) crushing the inorganic scale material to an appropriate particle size, dispersing it in papermaking water, and forming it into a predetermined shape of the diaphragm, such as a cone shape, by a normal papermaking method. The diaphragm was deposited on a paper mesh, impregnated with a thermosetting resin and a curing agent, and press-formed using a diaphragm-shaped heating mold.(2) The thermosetting resin, curing agent, and inorganic scale material were kneaded There is a diaphragm made by forming a prepreg into a sheet and curing it to the B stage, and then press-molding this in a heating mold with a predetermined diaphragm shape.

However, such conventional diaphragms have the following drawbacks.

The diaphragm according to (1) requires the above-mentioned work for each diaphragm, which makes it extremely difficult to mass-produce, and unlike paper pulp fiber, the inorganic scale material has almost no intertwining with each other, so the diaphragm shape It is extremely difficult to form a molded diaphragm, and there are large variations in the shape and physical properties of the molded diaphragm.

When the diaphragm according to (2) is press-molded into the shape of a diaphragm, the inorganic scale materials in the sheet are hardly intertwined with each other, so the layers of the inorganic scale materials easily peel off from each other, especially for dome-shaped diaphragms. Layer delamination is likely to occur at the rising portion or at the top of the cone-shaped diaphragm.

Furthermore, when an impact is applied to the molded product, delamination of the inorganic scale material occurs in a part of the molded product.

The present invention is a diaphragm that solves the above-mentioned drawbacks, and includes a high elastic fiber woven fabric layer, a layer mainly containing an inorganic scale material having high density and low elastic modulus layered on the woven fabric, and The present invention relates to a diaphragm comprising a layer mainly containing an inorganic scale material having a low density and high elastic modulus, and a thermosetting resin impregnated in each layer, and a method for manufacturing the same.Examples will be described in detail below. .

Graphite powder (density 2.30g/cm ³ , Young's modulus 3.43×10 ¹²
dyn/cm ² , average particle size 60 μm) and mica powder (density 2.85 g/cm ³ ,
Young's modulus 1.72×10 ¹² dyn/cm ² , average particle size 200 μm)
The material is then uniformly dispersed in water and allowed to naturally accumulate on a glass fiber woven fabric for about 30 minutes as a highly elastic fiber woven fabric, after which the water from the woven fabric is discharged under reduced pressure.

Next, the laminate obtained in each of the above steps was impregnated with a mixture of an epoxy resin and a curing agent, and cured to the B stage to obtain a sheet-like prepreg.

The prepreg was molded using a cone-shaped press mold (temperature: 170°C, press pressure: 10 kg/cm ² , time: 20 minutes) to obtain a cone-shaped diaphragm.

As shown in FIG. 1, the diaphragm 1 is made of an inorganic scale material 1b, which is mainly composed of low elasticity and high density mica powder and contains some high elasticity and low density graphite powder, on a glass fiber woven base layer 1a. However, an inorganic scale material layer 1c mainly composed of high elasticity and low density graphite powder and containing some low elasticity and high density graphite powder is further layered thereon, and these are integrated with epoxy resin. It has a similar configuration.

The composition of the diaphragm 1 was 30 wt% mica, 30 wt% graphite, 30 wt% epoxy resin, and 10 wt% glass fiber woven fabric.

As mentioned above, this structure was achieved by utilizing the difference in sedimentation speed in water during papermaking due to the difference in density and particle size of the two types of inorganic scale materials.

Next, a test piece was cut from the earlier diaphragm and its physical properties were measured, and it was found that the density was 1.95 g/cm ³ and the Young's modulus was 6.96.
The following values were obtained: ×10 ¹¹ dyn/cm ² , specific elastic modulus 3.6, and tan δ 0.010.

This value is the Young's modulus of the conventional example (1) of 5 to 6×
It has physical properties better than 10 ¹¹ dyn/cm ² .

This is because high elastic modulus layers are arranged on the upper and lower surfaces of the diaphragm, and a layer with a lower elastic modulus is interposed between them, thereby adding structural strength due to the Sanderch structure.

Further, according to the manufacturing method of the present invention, since there is no clear boundary between the mica layer and the graphite layer, it is possible to prevent deterioration of bending rigidity due to slippage at the boundary surface in this type of sandwich structure.

Furthermore, since the high elastic fiber woven fabric is used as the base layer, it is possible to prevent the inorganic scale material from peeling off when the sheet is molded into the shape of a diaphragm, and it is also possible to prevent partial peeling due to impact or the like.

In addition, in the method for manufacturing a diaphragm of the present invention, in order to fully utilize the difference in the settling speed of two types of inorganic scale materials in water, the particle size of the low-density inorganic scale material is reduced, and the particle size of the high-density inorganic scale material is reduced. It is desirable to select a large particle size of the scale material.

As explained above, the present invention includes a high elastic fiber woven fabric layer, a layer mainly containing an inorganic scale material having high density and low elastic modulus layered on the high elastic modulus fiber woven fabric layer, and A diaphragm and a high density diaphragm for an electroacoustic transducer characterized by comprising a layer mainly containing an inorganic scale material having a low density and high elastic modulus layered thereon, and a thermosetting resin impregnated in each layer. A process of dispersing an inorganic scale material with a low elastic modulus and an inorganic scale material with a low density and a high elastic modulus in water; A process of naturally depositing inorganic scale material on a highly elastic fiber woven fabric;
A vibration for an electroacoustic transducer characterized by comprising a step of impregnating the laminate obtained in the first step with a thermosetting resin and a curing agent to obtain a prepreg, and a step of heating and pressing the first prepreg to obtain a diaphragm. The present invention is a method for manufacturing a diaphragm, which allows a diaphragm with good physical properties to be obtained by an extremely simple manufacturing method, and has excellent practical effects.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and woven fabrics such as carbon fibers can also be employed as the high elastic fiber woven fabrics.

Alternatively, a highly elastic fiber woven fabric may be previously formed into a diaphragm shape, and the inorganic scale material may be deposited on this.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a diaphragm according to an embodiment of the invention. 1a is a high elastic fiber woven fabric layer, 1b is a layer mainly containing an inorganic scale material having high density and low elastic modulus,
1c is a layer mainly containing inorganic scale material having low density and high elastic modulus.

Claims (1)

[Claims] 1. A highly elastic fiber woven fabric layer 1a, a layer 1b mainly containing an inorganic scale material having high density and a low elastic modulus layered on the woven fabric layer 1a, and a layer 1b layered on the layer 1b. A diaphragm for an electroacoustic transducer, comprising a layer 1c mainly containing an inorganic scale material having a low density and a high elastic modulus, and a thermosetting resin impregnated in each layer. 2. The electroacoustic transducer according to claim 1, wherein the inorganic scale material having high density and low elastic modulus is mica, and the inorganic scale material having low density and high elastic modulus is graphite. diaphragm. 3. A process of cutting and dispersing inorganic scale material having high density and low elastic modulus and inorganic scale material having low density and high elastic modulus in water, and dispersing the inorganic scale material having high density and low elastic modulus in water. a step of naturally depositing an inorganic scale material having a high elastic modulus on a high elastic fiber woven fabric; a step of impregnating the laminate obtained in the step with a thermosetting resin and a curing agent to obtain a prepreg;
A method for manufacturing a diaphragm for an electroacoustic transducer, comprising the step of press-molding the prepreg into a diaphragm shape.