JPS5986993A - Diaphragm for loudspeaker - Google Patents

Abstract

PURPOSE:To reproduce satisfactorily a high-pitched sound by using a resin obtained by graft-polymerizing stylene on polyether which polymerizes 2,6-dimethl phenol. CONSTITUTION:A compound film which compounds talc to resin obtained by graft-polymerizing stylene on 2,6-dimethyl-1,4-phenylene ether or resin which mainly consists of said resin is formed in the shape of a diaphragm. The resin which compounds talc has a high elastic modulus and also a large specific elastic modulus, therefore, as for a loudspeaker diaphragm using this resin, its high band resonance frequency is high,and reproducing of a high-pitched sound becomes good. Also, the flexural ridgidity becomes high, and the distortion factor is reduced. Also, it is excellent in a water resisting property and a hot water resisting property, and also excellent in weather resistance, therefore, a loudspeaker using a diaphragm of this resin is suitable for use in the open air.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a diaphragm for a speaker in an electroacoustic transducer.

Conventional Structure and Problems Polyethylene terephthalate film (hereinafter referred to as polyester) has conventionally been used as a speaker diaphragm made of plastic.

However, polyester has a small elastic modulus (19000+
W/C11) In the case of a full-range speaker, the high-frequency resonant frequency (fH) is low and high-pitched sound reproduction is not necessarily good. Furthermore, although the elastic modulus of polyester is improved by applying biaxial stretching, there is a problem in that since the polyester is stretched, it shrinks when heated, making it difficult to form it into a predetermined shape of a diaphragm. OBJECTS OF THE INVENTION An object of the present invention is to provide a diaphragm for a speaker that has a high modulus of elasticity and is advantageous for high-frequency sound reproduction, and also has excellent moldability.

Structure of the Invention The speaker diaphragm of the present invention is made of a resin obtained by rough raft polymerization of styrene into poly(2,6-dimethyl-1,4-phenylene) ether obtained by polymerizing 2,6-dimethylphenol, or a resin obtained by polymerizing the resin. This is a composite film made by combining talc with resin as the main component, and molded into a predetermined diaphragm shape.

Thereby, it is possible to obtain a speaker diaphragm with a high elastic modulus, good high-frequency sound reproduction, and excellent moldability.

The elastic modulus, density, specific modulus, and bending rigidity of the resin composited with 20 wt% of talc are shown in Table 1 together with the resin containing no talc and polyester.

Table 1 ■Weight 100 f/n? As shown in Table 1, this talc composite resin has a high elastic modulus and a high specific elastic modulus, so speaker diaphragms using this resin have a high high resonance frequency (IH) and good high-frequency sound reproduction. Become something. Furthermore, since the bending rigidity is high, the strain rate is reduced. This talc composite resin has excellent water resistance, hot water resistance, and weather resistance, so a speaker using a diaphragm made of this resin is suitable for outdoor use. Moreover, since it is self-extinguishing in a heat resistance test, a diaphragm made of this film has flame retardancy. In addition, this resin film is easy to mold and can be vacuum formed, pressure formed, vacuum pressure formed, and hot press molded, and is excellent in mass production.

Description of Examples [Example 1] A resin for molding a diaphragm was obtained by graft polymerizing styrene to poly(2,6-dimethyl-1,4-phenylene) ether obtained by polymerizing 2,6-dimethylphenol. A composite film containing 20 wt% of Merck in resin was used. The elastic modulus of this film is 39.0OOIj/□j
The elastic modulus of the film without talc (24, ooo
KV/ctl) was 1.6 times or more. This film was molded into a diaphragm shape by air pressure molding to obtain a cone-shaped diaphragm with a diameter of 40 mm and a thickness of 100 μm. Figure a shows the acoustic characteristics using this diaphragm, Figure b shows the acoustic characteristics using the talc-free resin diaphragm with the same diameter and thickness, and Figure C shows the polyester vibration with the same diameter and thickness. This shows the acoustic characteristics using a board. As is clear from the figure, the speaker using the composite film diaphragm of this example has a high elastic modulus and a high specific elastic modulus, so the high frequency resonance frequency f
H was high and high-pitched sound reproduction was good.0 [Example 2] Talc was added to the above-mentioned resin for 1. The elastic modulus of the Owt% composite film was 26, OOO(+(IP/cA)).

In the same manner as in Example 1, the frequency characteristics of a speaker in which this composite film was molded into a diaphragm shape were compared with those in which a diaphragm of the above-mentioned ILM without talc and a diaphragm of a polyester film were used. Similar to No. 1, the high-frequency resonant frequency fH was high and high-pitched sound reproduction was good.

[Example 3] The elastic modulus of a composite film in which 60 wt % of talc was combined with the above-mentioned resin was 61,000 KfAd. Example 1
In the same way as in Example 1, the frequency characteristics of a speaker with a diaphragm made of this composite film are similar to those of a speaker with a diaphragm made of the above film without talc composite and a diaphragm made of polyester film. The high-frequency resonant frequency fH was high and high-pitched sound reproduction was good.

In the above examples, PoIJ (2,6-dimethyl-1.
A resin obtained by rough raft polymerization of styrene to 4-phenylene) ether is used.In addition to this, the base material may be one in which a thermoplastic resin is added to the above-mentioned resin to improve its own properties.

For example, polyarylate is added to improve heat resistance, polyethylene, polypropylene, polyethylene terephthalate, or polybutylene terephthalate is added to improve solvent resistance, and polyethylene is added to improve moldability. It may be one to which vinyl chloride or bolyate is added.

Effects of the Invention As detailed above, according to the present invention, poly(2,6-dimethyl-1.4
-7 enylene) A speaker diaphragm with good high-frequency sound reproduction and excellent moldability because it uses a resin obtained by graft polymerizing styrene to ether or a composite film made by combining Merck with a resin mainly composed of that resin. can be obtained.

[Brief explanation of drawings]

The figure is a comparative curve diagram of frequency characteristics of an embodiment of the present invention and a conventional speaker.

Claims (1)

[Claims] Poly(2,6-
A diaphragm for a speaker, characterized in that a composite film is formed of a resin obtained by graft polymerizing styrene to (cymethyl-1,4-phenylene) ether, or a composite film composed of talc and a resin mainly composed of the resin.