JPS63246098A - Diaphragm for speaker - Google Patents

Abstract

PURPOSE:To obtain the speaker with a satisfactory characteristic by using a diaphragm to mix, heat and mould a polyamide epichlorohydrin resin having chitosan and epoxy radical to deacetylate a craft pulp and a chitin. CONSTITUTION:A solution to dissolve chitosan to deasetylate a craft paper and chitin, which is a natural high polymer, to a weak acid solution is mixed so that a pair pulp weight ratio can be 5wt% at a solid. Further, an epichlorohydrin polyamide resin solution is mixed so that the pair pulpe weight ratio can be 3wt% at the solid, paper-making is executed by a cylinder system, a heating processing is executed at 130 deg.C and simultaneously, molding is executed to a diaphragm shape. Thus, fibers are chemically linked and compared with a structure by the entanglement of the fibers like the conventional paper pulp, etc., a strength becomes larger very much and a rigidity becomes higher, an excellent raw material is obtained as the diaphragm and a speaker having a satisfactory acoustic characteristic can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a diaphragm for a speaker used in sound output equipment and the like.

Conventional technology In recent years, in the cassette tape recorder, micro cassette tape recorder, and high-fidelity stereo industries, there has been a demand for speakers with better output sound pressure, distortion rate, and flatness than before in terms of the acoustic characteristics of speakers used as audio output equipment. Speaker diaphragms, which influence acoustic characteristics, are becoming increasingly important.

A speaker consists of a vibration system such as a diaphragm, a voice coil bobbin, and a voice coil, and a magnetic circuit system (not shown) that includes a magnet, a ball, a plate, and a yoke. When an audio current flows through a voice coil in a uniform magnetic field, a vertical force is generated in the voice coil, causing it to vibrate. This vibration is transmitted correctly to the vibration of the diaphragm and is emitted as a sound wave (for example, Toshio Hayasaka: Introduction to Acoustic Engineering, Nikkan Kogyo Shimbun).

Problems to be Solved by the Invention However, ideally, the diaphragm of a speaker should make a piston movement over the frequency band used, but if the diaphragm deforms during vibration or split vibration occurs, the sound pressure-frequency characteristics will deteriorate. , distortion rate, phase characteristics, etc. deteriorate, and high-fidelity reproduction is hindered. In addition, conventional paper cone diaphragms and plastic stationary plates have low high-frequency resonant frequencies because the diaphragm material has a small E/ρ (E2 modulus of elasticity, ρ: density).
The drawback was that the speakers could not reproduce high frequencies.

In view of the above-mentioned problems, the present invention provides a diaphragm for a speaker that does not cause deformation of the diaphragm or split imaging during vibration, and has a high high-frequency resonant frequency.

Means for Solving the Problems To achieve this object, the speaker diaphragm of the present invention is made of a mixture of kraft pulp, chitosan, which is a natural polymer that has deacetylated chitin, and polyamide/epichlorohydrin resin. A thermoformed sheet is used as the imaging plate.

Function The diaphragm of the present invention is made of chitosan, which is a natural polymer material with a high elastic modulus, kraft pulp, which has a high mechanical internal loss, and a polyamide/epichlorohydrin resin for crosslinking the two materials using epoxy groups. Because it is mixed and heat-formed, unlike conventional paper pulp, the fibers are not only intertwined, but also chemically bonded together, increasing their strength. In addition, the effect of kraft pulp increases mechanical internal loss, so
It is possible to obtain a speaker with few flaws in frequency characteristics and excellent sound pressure-frequency characteristics, distortion rate, and phase characteristics. Furthermore, since the diaphragm material of the present invention uses a material whose main component is kraft pulp, it can be manufactured by conventional papermaking methods, and is therefore extremely suitable for mass production.

EXAMPLE A speaker diaphragm according to an example of the present invention will be described below.

A speaker diaphragm according to an embodiment of the present invention uses Sheetla, which is a mixture of kraft pulp, chitosan (deacetylated chitin, which is a natural polymer), and polyamide/epichlorohydrin resin having an epoxy group, and then heated and molded.

The method for manufacturing the speaker diaphragm of this example will be described below.

First, kraft pulp and a solution of chitosan, which is a natural polymer deacetylated chitin, dissolved in a weakly acidic solution (solid content 3%) were mixed so that the weight ratio of solid content to the pulp was 5 wt%. Furthermore, an epichlorohydrin polyamide resin solution was mixed so that the solid content was 3 wt% based on the weight of the pulp, and the paper was made using a circular mesh method.
At the same time, it was heat-treated for 0 minutes and molded into a diaphragm shape.

The physical properties of the diaphragm molded as described above were such that the elastic modulus of the diaphragm increased when the mixing ratio of chitosan was Swt% and the epichlorohydrin polyamide resin was 3wt%.

Further, if the mixing ratio is increased further, the density becomes higher and the specific elastic modulus decreases.

In actual use, the mixing ratio can be arbitrarily adjusted depending on the physical properties required of the diaphragm.

As described above, according to this example, a diaphragm made of a mixture of kraft pulp, chitosan (deacetylated chitin, which is a natural polymer), and polyamide/epichlorohydrin resin and heat-molded can be used in place of a conventional paper cone diaphragm. In comparison, since the fibers are chemically bonded to each other, the rigidity becomes cylindrical, suppressing the deformation of the diaphragm and suppressing one-division resonance, resulting in good acoustic characteristics.

In addition, in this example, the shape of the image pickup plate may be a cone shape instead of a dome shape to obtain the same effect, and good results can also be obtained when used as the surface material of a flat plate image pickup plate with a sandwich structure. That's what you get.

Effects of the Invention As described above, the present invention uses as a diaphragm a material obtained by thermoforming a mixture of kraft pulp, chitosan obtained by deacetylating chitin, which is a natural polymer, and polyamide/epichlorohydrin resin having an epoxy group. The epoxy groups react with the hydroxyl groups of pulp fibers and the amino groups of chitosan to chemically bond the fibers together, and because chitosan molecules have positive polarity and pulp fibers have negative polarity, electrical This makes it much stronger and more rigid than conventional structures such as paper pulp, which are made up of intertwined fibers, making it an ideal material for making diaphragms.

Furthermore, since there is also slippage between the fibers, the internal loss is large, and a speaker with good acoustic characteristics can be realized.

In addition, the mechanical internal loss is reduced by the effect of kraft pulp, so there are few fluctuations in frequency characteristics, and it is possible to obtain a speaker with excellent sound pressure-frequency characteristics, distortion rate, and phase characteristics. Further, since the diaphragm element of the present invention uses a material whose main component is kraft pulp, it can be manufactured by conventional papermaking methods, and is therefore extremely suitable for mass production.

Claims (1)

[Claims] A speaker diaphragm characterized by using a heat-formed sheet made from a mixture of kraft pulp, chitosan which is a deacetylated natural polymer chitin, and polyamide/epichlorohydrin resin having an epoxy group.