JP2001145189A - Diaphragm for loudspeaker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a diaphragm for a loudspeaker in which internal loss can be increased without sacrificing its flexural rigidity, by using special pulp which is called zerolite pulp and is prepared by depositing zeolite on a cellulose base material. SOLUTION: A diaphragm for this loudspeaker is constituted by manufacturing a sheet by using an inorganic porous crystal-hydrophilic high polymer composite material composed of a hydrophilic polymer base material containing inorganic porous crystals in its body, independently or together with another fibrous material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a paper speaker diaphragm for an electroacoustic transducer.

[0002]

2. Description of the Related Art Physical properties required of a diaphragm for a speaker include a low density, a high elasticity and a moderate internal loss,
In addition, there is no mechanical fatigue and good weather resistance and the like.

Various polymer materials, metals, ceramics, and the like have been proposed and used to satisfy the above physical properties, but all of them are expensive due to physical property control and manufacturing problems.

On the other hand, paper diaphragms are often used at present because of easy control of physical properties and easy production. The mechanical properties of the paper diaphragm are determined by the physical properties of the single fibers used, the bonding strength between the fibers, and the bonding area.

Currently used paper diaphragm materials are made of wood pulp or non-wood pulp alone, or mixed with natural fibers such as hemp or cotton or chemical fibers such as carbon or aramid to control physical properties. I went.

[0006]

These materials are used for improving the elastic modulus or bending stiffness, the internal loss, and reducing the density. For example, in the case of carbon or aramid fiber, the improvement of the elastic modulus, the density, etc. Can be reduced.
However, when used for low-pitched sound reproduction, it is effective to reduce the density, but it is reproduced up to the high-pitched sound region due to the improvement in the elastic modulus, and is unsuitable for use in combination with, for example, a tweeter. In the case of natural fibers, cotton such as linter is mainly used to reduce the propagation speed for reproducing low-pitched sound.
There has been a problem that the next higher harmonic distortion increases, which tends to be unfavorable in the sense of hearing.

The present invention has been proposed in view of the above, and an object thereof is to impair the bending rigidity by using a special pulp material in which zeolite 2 is supported on a cellulose substrate 1. It is an object of the present invention to provide a speaker diaphragm capable of measuring an increase in internal loss without any problem.

[0008]

According to the present invention, there is provided an inorganic porous crystal-hydrophilic polymer composite in which a hydrophilic polymer base material has an inorganic porous crystal in the substance itself, Alternatively, the above-mentioned object is achieved by being mixed with another fiber material. Further, it is characterized in that zeolite 2 is used for the inorganic porous crystal and cellulose substrate 1 is used as the hydrophilic polymer substrate. further,
The cellulose substrate 1 is characterized by being based on wood pulp or non-wood pulp.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The pulp material used in the present invention is as follows.
An inorganic porous crystal-hydrophilic polymer composite as disclosed in JP-A-10-120923, which is called zeolite cellulose or zeolite pulp, and has an average zeolite particle diameter of 2 to 3 μm according to the development of Rengo Co., Ltd.
m.

That is, in this pulp material, a hydrophilic polymer base material such as cellulose made of wood pulp is composed of an inorganic porous crystal-hydrophilic polymer composite having an inorganic porous crystal therein, that is, an inorganic porous crystal inside. Say.

Examples of the inorganic porous crystal include an inorganic ion exchanger crystal having an ion exchange capacity such as zeolite (porous silicate hydrate such as aluminum and calcium). There is no particular limitation as long as it does not dissolve, decompose or disintegrate the material.

The substance of the hydrophilic polymer substrate is, for example,
When the substrate is cellulose, it means the inside of the polymer material constituting the cellulose substrate, and having inorganic porous crystals in the entity means that the inside of the cellulose substrate 1 is, as shown in FIG. This is a state in which zeolite 2, which is an inorganic porous crystal, is packed in a honeycomb shape. FIG. 2 is a schematic view of a conventional composite of cellulose and zeolite, in which zeolite 2 adheres only to the surface of cellulose substrate 1 and has a slightly flat shape.

In the zeolite-cellulose composite of the present invention, since a large number of zeolites 2 are present inside the cellulose substrate 1, the cross-sectional shape is rounder than that shown in FIG. As a result, bending rigidity is improved as a physical characteristic. For this reason, when this pulp material is formed to produce a diaphragm for a speaker, there is an advantage that the distortion sound on the audibility due to friction between fibers is improved.

[0014] In addition, since zeolite has a high chemical bonding property with cellulose fiber as a basic chemical property, as a general rule of physical properties, if the pulp fiber diaphragm material is made bulky, the Young's modulus decreases, so It is possible to prevent a large decrease in speed.

[0015] Such an inorganic porous crystal-hydrophilic polymer composite is prepared by combining a plurality of water-soluble compounds and a basic substance with a hydrophilic polymer in the presence of a swollen hydrophilic polymer substrate. It can be produced by reacting in the body of the base material.

In the following, the inorganic porous crystal is zeolite,
The production method when the hydrophilic polymer is a cellulose substrate will be specifically described.

First, a cellulose substrate is impregnated with an aqueous solution of a silicon compound such as sodium metasilicate. The cellulose substrate impregnated for a predetermined time and the amount of the solution is adjusted is immersed in a mixed aqueous solution of an aluminum compound such as sodium aluminate and a basic substance such as sodium hydroxide at a predetermined temperature for a predetermined time.

Through the above steps, zeolite is generated in the body of the cellulose substrate, and a zeolite-cellulose composite can be obtained.

The silicon compound, aluminum compound, and basic substance are not limited to those described above, and various combinations are possible.

Further, the manufacturing method is not limited to the above-described steps.
The cellulose substrate may be impregnated with an aqueous solution of an aluminum compound first, and then immersed in a mixed aqueous solution of a silicon compound and a basic substance, and further mixed with an aqueous solution of a silicon compound or an aluminum compound and a basic substance. May be impregnated with a cellulose substrate, and then immersed in another remaining aqueous solution.

Among the zeolite-cellulose composites thus obtained, those using a pulp material as a cellulose substrate (hereinafter simply referred to as zeolite pulp) are used in the present invention.

This zeolite pulp can be used alone as a diaphragm material, and can be easily mixed with other pulp materials and the like at an arbitrary mixing ratio. When the speaker diaphragm is used for full-band reproduction, when a conventional material, for example, wood pulp (NBKP) is 100%, or when chemical fibers such as carbon and aramid are mixed and used, the propagation speed Has a shortcoming, but has a drawback that a peak is formed in a high frequency range due to low internal loss.

However, when the zeolite pulp used in the present invention is used as a speaker diaphragm, it is possible to increase the internal loss without significantly lowering the propagation speed and suppress the peak in the high-frequency range. , Very good characteristics can be obtained.

For low-frequency range reproduction, it is desirable to increase the bending rigidity (lower the density) than the propagation speed and to increase the internal loss without increasing the propagation speed. Conventionally, linters and the like have been mainly used, but they have never been satisfactory due to low bending rigidity.

When zeolite pulp is used for bass reproduction, bending rigidity can be increased by lowering the density. When a nitrocellulose-based lacquer is impregnated, the internal loss can be further increased without impairing the bending rigidity, and the treble peak can be reduced.

In the case of a chemical fiber such as carbon fiber, the fiber itself is not impregnated, so that the effect of impregnation is small. However, since zeolite pulp has a higher water absorption of lacquer than other materials, the effect of the impregnating agent is greater than other materials, and it is possible to obtain not only the diaphragm material but also such a secondary effect. It is a material suitable for a diaphragm material, and the present invention has been made by focusing on these matters.

[0027]

Embodiment 1 The manufacturing method of the present invention will be described below. The zeolite pulp was manufactured using Rengo Co., Ltd. (average zeolite particle diameter of 2-3 μm). First, a zeolite pulp alone was formed into a speaker diaphragm. As a result, the bending stiffness is improved, and the propagation speed of the diaphragm is not increased and is not greatly reduced. Therefore, it is possible to obtain a diaphragm having good sound quality over the entire range from the low band to the high band. it can.

[0028]

Example 2 Next, a disintegrated zeolite pulp was mixed with wood pulp (NBKP) beaten at 19 ° SR at a ratio of 30%, and after hand-making, a hot-pressed paper sheet was prepared. Physical properties were evaluated by the method.

As a comparison, wood pulp (NBKP) 100
%, Wood pulp (NBKP) mixed with 30% carbon fiber, wood pulp (NBKP) mixed with 30% linter, wood pulp (NBKP) 7
A mixture of 0% and 30% carbon fiber was simultaneously prepared and measured.

Table 1 shows the results of A to D.

[Table 1]

A diaphragm is manufactured from the pulp material having the above specifications.
A speaker having a diameter of 20 cm was manufactured, and its frequency characteristics were measured. The result is shown in FIG. In this figure, as shown in B, it can be seen that a mixture of wood pulp (NBKP) mixed with zeolite pulp at 30% yielded good sound quality while suppressing dips and peaks in the middle and high frequencies.

[0032]

Example 3 A diaphragm was manufactured from a pulp material obtained by mixing 10% of zeolite pulp with wood pulp (NBKP), a speaker having a diameter of 10 cm was manufactured, and its frequency characteristics were measured. FIG. 4 shows the results. In the figure, E shows the characteristics in the case of wood pulp (NBKP) + 10% zeolite pulp in the present invention according to Example 3 and F shows the characteristics in the case of wood pulp (NBKP) 100%. As is apparent from FIG. 4, the sound quality is better when the zeolite pulp is mixed.

In the above embodiment, wood pulp (NBK)
30% or 10% zeolite pulp based on P)
Although two mixed examples have been described, the present invention is not limited to these two examples, and the sound quality can be improved as compared with the case of 100% wood pulp (NBKP) if mixed within a range of 1 to 70%. .

In addition to wood pulp (NBKP),
Non-wood pulp such as kenaf and banana may be mixed together, and in this case, almost the same characteristics can be obtained. It is preferable to use non-wood pulp from the viewpoint of preventing natural destruction such as protection of forest resources.

Further, by appropriately mixing a chemical fiber material such as aramid or carbon with these, physical properties can be controlled, and a diaphragm having desired characteristics can be obtained.

[0036]

As described above, according to the present invention, the use of zeolite pulp does not lower the propagation speed of the diaphragm, and therefore suppresses the high-frequency peak without lowering the high-frequency limit. This was realized.

Further, since the bending rigidity can be improved without increasing the propagation speed of the diaphragm and the internal loss can be increased, low-frequency reproduction is excellent, and a diaphragm material excellent as a full-range speaker can be obtained. I was able to.

[Brief description of the drawings]

FIG. 1 shows a schematic diagram of an inorganic porous crystal-hydrophilic polymer composite used in the present invention.

FIG. 2 is a schematic view of a conventional example corresponding to the present invention.

FIG. 3 shows a comparison of frequency characteristics between a second example of the present invention and a conventional example in a speaker having a diameter of 20 cm.

FIG. 4 shows a comparison of frequency characteristics between a third embodiment of the present invention and a conventional example in a speaker having a diameter of 10 cm.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cellulose base material 2 Zeolite B, E The present invention

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kotoshi Sugiyama 4-1-1, Okai, Fukushima-ku, Osaka-shi, Osaka Inside Rengo Co., Ltd. (72) Inventor Naoaki Hashimoto 4-chome, Okai, Fukushima-ku, Osaka-shi, Osaka No.1-1186 Inside Rengo Co., Ltd. Central Research Laboratory (72) Inventor Motoomi Okabe 4-1-1 Okai, Fukushima-ku, Osaka-shi, Osaka Prefecture Inside Rengo Co., Ltd. Central Research Laboratory (72) Inventor Kiyotaka Miyashita Musashino, Akishima-shi, Tokyo F-term (reference) in 3-2-35, Fostex, Inc. 5D016 CA05 CA07 EA03 EA05 EB02 EB08 JA01

Claims (3)

[Claims] An inorganic porous crystal-hydrophilic polymer composite in which a hydrophilic polymer base material has an inorganic porous crystal in its body is formed alone or mixed with another fiber material. A diaphragm for a speaker, comprising: 2. A cellulose substrate (1) using zeolite (2) as an inorganic porous crystal and a hydrophilic polymer substrate.
The diaphragm for a speaker according to claim 1, wherein the diaphragm is used. 3. The diaphragm for a speaker according to claim 2, wherein the cellulose substrate (1) is made of wood pulp or non-wood pulp.