JPS5975797A - Diaphragm for speaker - Google Patents

Abstract

PURPOSE:To obtain a speaker diaphragm which has high elasticity, high sound reproduction characteristics, and superior formability and solvent resistance, by forming resin obtained by mixing a small amount of carbon with polyether. CONSTITUTION:This invented speaker diaphragm is manufactured by forming the resin obtained by mixing a small amount of carbon with polyether produced by condensation reaction between sodium salt of bisphenol A and 4.4'-dichlorodiphenylsulfone in a specific diaphragm shape. A polyether film has a high elastic modulus and high specific elasticity, so the speaker diaphragm using this polyether film provides excellent high-frequency-range reproduction. The polyether film superior watertightness and resistance to hot water and is formed easily because a small amount of carbon is incorporated although its formability is inferior; vacuum forming, pressure forming, vacuum pressure forming, and hot press forming are possible and the mass-productivity is improved as compared with when the polyester film and a polyether film are used indepently.

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 (1900 to 9
/cA'), in the case of a full-range speaker, the high-frequency resonant frequency (fa) is low and high-frequency sound reproduction is not necessarily good. Furthermore, although the elastic modulus of polyester is improved by biaxial stretching, heating of the stretched polyester causes shrinkage, making it difficult to form the polyester into a predetermined shape for use as a diaphragm. there were.

OBJECTS OF THE INVENTION An object of the present invention is to provide a speaker diaphragm that has a high modulus of elasticity and is excellent in reproducing high-pitched sounds, as well as having excellent moldability and solvent resistance.

Structure of the Invention The speaker diaphragm of the present invention is made by forming a resin into a predetermined diaphragm shape by combining a small amount of carbon with a polyether obtained by a condensation reaction of a sodium salt of bisphenol and 4,4'-dichlorodiphenylsulfone. It is molded. As a result, it is possible to obtain a speaker diaphragm that has a high elastic modulus, good high-frequency sound, and excellent moldability and solvent resistance.

The elastic modulus and density of this polyether film.

The specific elastic modulus 1 bending rigidity is shown in Table 1 together with the polyester.

Table 1 (*): 11th visit 1oofl/I The polyether film is as shown in Table 1.

Because the elastic modulus is high and the specific elastic modulus is large, speaker diaphragms using this polyether have a resonance frequency in the 1t-ii region (
fH) is high, and high-frequency sound reproduction is good.

In addition, since it has a lower density than polyester, its efficiency as a diaphragm is higher, and its rigidity is higher, so the distortion rate is reduced.

In addition, the polyether film has water resistance and lT1. It has excellent hydrothermal properties and is self-extinguishing in flame resistance tests, so diaphragms made of this film have excellent flammability. Moreover, although polyether films have difficulty in forming, they contain carbon, which makes them easy to form, and vacuum forming, pressure forming, vacuum pressure forming, and hot press forming are possible, making polyester films and polyether films easy to form. Superior hanging and productivity compared to ether film alone.

Unfortunately, the above polyether is easily attacked by aromatic and ketone solvents, but its solvent compatibility is improved by adding carbon to it. The elastic modulus of the polyether after adding 10 molecules of toluene and atom at room temperature decreased by about 40%, but the elastic modulus of the polyether film composited with Iwt% carbon decreased by only about 25%.

FIG. 1 shows the relationship between heating time and carbon content during vacuum forming of a polyether film.

In this case, the heating time means the time until the vacuum forming can be carried out sufficiently while keeping the heating temperature constant at 2808C. As is clear from FIG. 1, when the carbon content was 0.1 wt%, the carbon content began to decrease during heating.At 1 wt%, no rapid decrease in the heating time was observed. Incidentally, if the carbon content exceeds 6.t%, conductivity will be imparted. For this reason, it is desirable that carbon be contained within a range not exceeding 15 wt%.

Description of Examples As 1ml l1li for diaphragm molding, bisphenol A
The polyether obtained by the condensation reaction of the sodium salt of and 4,4'-dichlorodiphenyl sulfone is
A resin composited with Swt% carbon was used. The diaphragm was formed using the vacuum forming method, with a positive diameter of 40 mmφ and a thickness of 1.
A cone jW diaphragm with a diameter of 00 μm was obtained.

Figure 2 a shows the acoustic characteristics of a speaker using this diaphragm.
b in Figure 2 shows the acoustic characteristics using a polyester diaphragm with the same diameter and thickness.As is clear from Figure 2, a speaker using a polyether film containing carbon as a diaphragm is Since the elastic modulus is high and the specific elastic modulus is high, the field resonant frequency fH is high, and high-pitched sound reproduction is improved.Efficiency is also high.

Effects of the Invention As detailed above, according to the present invention, a small amount of carbon is combined with a polyether obtained by a condensation reaction of a sodium salt of bisphenol and 4,4'-dichlorodiphenyl sulfone. It is possible to improve moldability while taking advantage of its physical properties. Therefore, the treble "4" is good, the efficiency is high, and the frequency characteristics are excellent.
Students will also learn the advantage of being able to obtain a speaker diaphragm with excellent moldability and solvent distribution property.

[Brief explanation of the drawing]

Figure 1 shows 1; l used in the speaker diaphragm of the present invention.
Figure 2 shows the relationship between heating time and carbon content in tll-r, and Figure 2 is a comparison diagram of the frequency characteristics of a speaker diaphragm according to the present invention and a speaker using a conventional polyester diaphragm.

Claims (1)

[Claims] Bispheno-11 sodium salt, 4.4'--
) A diaphragm for a speaker, characterized in that it is formed by molding a resin in which a small amount of carbon is combined with polyether obtained by a condensation reaction of chlorodiphenyl sulfone.