JPH0492599A - Acoustic diaphragm member - Google Patents

Abstract

PURPOSE:To obtain an acoustic diaphragm member with fast acoustic velocity and big internal loss whose characteristic doesn't change or fluctuate with lapse of time by using an aromatic copolymerized amide film having >=900kg/mm<2> tensile modulus. CONSTITUTION:This acoustic diaphragm member is prepared after forming the film having tensile modulus more than 900kg/mm<2>, by a hot press formation, and the film is substaintially constituted of an aromatic copolymerized amide shown in formula I or/and II (where Ar1-Ar3 are 1 or >=2 kinds selected from groups of lower alkyl and halogen substituted product), and has 1.45-1.60g/cm<3> density. That is, an appropriate flexiblity is imparted to the para oriented aromatic copolymerized amide having a rigid molecular structure by the introduction of an ether linkage. Thus, a residual stress in the body formed by the hot press formation is small so that the acoustic diaphragm members whose characteristic is superior and hardly change with the lapse of time and under various circumstances, can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an acoustic vibration system member molded from a resin film, and more particularly to an acoustic vibration system member with significantly improved acoustic performance.

[Prior art] Acoustic vibration system members include diaphragms, voice coil bobbins, center caps, suspensions (edges, dampers, etc.), but recently, diaphragms made of resin film have become popular. It is used to heat-form a film of polyester, polypropylene, polyether sulfone, polyimide, etc. into a predetermined shape.

However, these conventionally used resin films have the following drawbacks.

That is, the conventional film described above has a speed of sound propagation (hereinafter referred to as "
There are few things that have high internal losses (
(hereinafter referred to as "r tan δ") is small and tends to resonate in the used frequency band, which often deteriorates the characteristics. In addition, a polypropylene film or the like with a large tan δ is sometimes used, but those with a large tan δ have the disadvantage that the speed of sound is slow and the high frequency reproduction limit frequency is low.

Aromatic polyamide films are known as films with a high sound velocity; for example, JP-A No. 63-278491
No. 1-78496, and JP-A-1-1-1
Japanese Patent No. 35297 discloses an acoustic vibration system member made of an aromatic polyamide film. These devices have a wide sound reproduction band and low distortion due to split vibration.

However, although the vibration system members described in the examples of these prior art have the above-mentioned characteristics, they have poor creep resistance, and the sound characteristics often slightly change after molding.
In addition, dissatisfaction remained that the design was poor because it was difficult to color.

[Problem to be solved by the invention]

The purpose of the present invention is to solve the above-mentioned drawbacks of the conventional acoustic vibration system members, and by using an aromatic copolyamide film with a special chemical composition, the speed of sound is extremely high and the internal loss is large. It is an object of the present invention to provide an acoustic vibration system member whose characteristics do not change or vary over time, which can be easily colored, and which has an excellent design.

(Means for solving the problem) As a result of intensive research to solve this problem, it was discovered that an excellent acoustic vibration system member could be provided by using an aromatic copolyamide film having a specific ether bond. This invention was made based on this knowledge.

That is, the present invention provides an acoustic vibration system member formed by thermoforming a film having a tensile modulus of 900 kg/- or more into a predetermined shape, in which the film substantially satisfies the following formula (1) or/and (2). Aromatic copolyamide; NHArt N
HCOArz CO (1) NHAr,, c
o (2) (However, A r
1-A r 3 is one or two selected from the group consisting of Xφ>-@← or/and alkyl and halogen substituents, in which 5 to 50 mol% of the total of A r , ~A, r 3 is
More than a species. ), and has a density of 1.45 to 1.60 g/cTl.

In the present invention, it is important to use an aromatic copolyamide film having a tensile modulus of 900 kg/- or more. A film with a high tensile elastic modulus has a high acoustic wave elastic modulus in −C, and the sound velocity in the film also increases, so that the frequency range that can be used as a vibrating member is widened.

The tensile modulus of the film is preferably 1000 kg/lI
It is more than I.

The film used in the present invention consists essentially of an aromatic copolyamide, and it is essential that the aromatic copolyamide contain specific ether bonds. That is,
The film of the present invention substantially has the following formula (1) or/and (
2) Aromatic polyamide; -NH-A, r, -NHCO
-Arz-CO-(1)NH-Ar, -CO-(2
) (However, A r 1 to A r 3 are A r + ~
It is one or more selected from the group consisting of 5 alkyl and halogen substituted products of A r 3 in total. ). It is well known that a film made of aromatic polyamide with disorientation is used for high-speed acoustic diaphragms, but the aromatic copolyamide film of the present invention containing a specific amount of specific ether bonds has a unique property. It was found that it has the following properties. In other words, the individually oriented aromatic polyamide film maintains its inherent high sound velocity and high internal loss, and these characteristics do not change at all over time.
It has also been found that coloring is easy and the material can be used as an acoustic vibration system member with excellent design. These favorable characteristics are due to the fact that the introduction of ether bonds imparts appropriate flexibility to the discrete aromatic copolyamide, which has a rigid molecular structure, and this reduces the stress remaining in the hot-press molded product. This is presumed to be due to the fact that the characteristics change or vary less. Furthermore, the ease of coloring is thought to be related to the ease of molecular movement.

The acoustic vibration system member of the present invention is formed by hot-pressing a specific film, and the film has a diameter of 1.45 to 1.
It is necessary to have a density of 60 g/afl.

Such a density belongs to a relatively high level for an aromatic polyamide. In other words, the crystallinity is quite high or/
It has structural characteristics such as halogen substitution and high electron density.

Such characteristics are one of the requirements for the aromatic polyamide used in the present invention to have a high sound velocity even though it is a copolymer.

In the present invention, thermoforming may be carried out by, for example, press-molding the film in a mold heated to at least 200'C or higher, cooling the mold to an appropriate temperature in the pressed state, and then demolding the film. Can be molded.

Acoustic vibration system members in the present invention include diaphragms for speakers, microphones, and earphones, center camps for speakers, voice coil bobbins for speakers, suspensions for speakers, edges, etc., and are not limited to these single members. , it is also possible to integrally mold two or more parts that should be adjacent to each other.

Furthermore, a vibration system member having a laminated structure can also be obtained by adhering the aromatic copolyamide film of the present invention with an adhesive in advance and then thermoforming it.

The vibration system member of the present invention has excellent characteristics such as a sound velocity of at least 2800 m/sec or more and a tan δ (internal loss) of 0.03 or more, and these characteristics also change over time.
It hardly changes even under various environments.

In addition, in order to adjust the surface properties, moldability, and acoustic properties, glass fibers, carbon fibers, carbon particles, carbon whiskers, talc, silica, etc. may be added, or voids may be added by using a foaming method. You may let them.

The film used in the present invention is, for example,
It can be manufactured by the methods disclosed in JP-A No. 7886, JP-A-52-84245, JP-A-56-104937, and the like.

〔Example〕

Example 1 Example 1 is an example of molding a cone-shaped diaphragm. Using a press mold consisting of a male mold and a female mold each provided with a cooling medium passage, the female mold is 350"C1 the male mold is 250°
C, the thickness is approximately 38 μm, and the tensile modulus is 1.
030kg/mj, elongation 5o%, density 1.50g/aa
A cone-shaped diaphragm was obtained by press-molding a film having a sound velocity of 3000 va/sec and a JAN60.046.

This film is an aromatic copolyamide with the following chemical structure.

When 10 speakers were made from the obtained diaphragm and a frequency characteristic diagram of the speakers was created, no differences were found among the 10 speakers, and there was no change even after leaving them for about a month.

Comparative Example 1 Similarly to Example 1, a cone-shaped diaphragm was made from a film having the following characteristics.

The film used has the following chemical structure: thickness of approximately 38 μm, tensile modulus of 1200 kg/mj, elongation of 40%, and density of 1.50 g/m.
cJ, the sound velocity was 3100 m1 sec, and the tan δ was 0.032.

In addition, during molding, the female mold was heated to 380°C and the male mold to 300°C.
Each test was carried out by heating to °C.

As in the example, a frequency characteristic diagram was created, but there were slight differences among the five speakers, and when remeasured one month later, a slight shift toward the lower frequency side was observed.

A film was made by a wet method from an aromatic copolyamide having the chemical structure of Example 2, and the film in a water-containing state before drying was mixed with an organic dye containing 5% by weight of cationic dye Guiacryl Red GLN (manufactured by Mitsubishi Chemical Industries, Ltd.). It was immersed in a solvent for 5 minutes to incorporate the dye and then stretched and dried to obtain a red film. This film has a thickness of 50 μm and a tensile modulus of 9
50 kg/d, elongation 90%, density 1.45 g/ci,
A dome-shaped diaphragm was obtained by press-molding the film at a sound speed of 2800 m/sec and an electric an δ of 0.039 using a mold heated to 300°C for a female mold and 230°C for an A-type. The diaphragm was bright red.

Comparative Example 2 The film used in Comparative Example 1 was dyed in the same manner as in Example 2 during wet film formation. The characteristics of the slightly red-colored film and the characteristics of the diaphragm (speaker) made from it were almost the same as in Comparative Example 1, but the obtained diaphragm had black to red corners and had a poor appearance. Ta.

〔Effect of the invention〕

Since the acoustic vibration system member of the present invention is made of a specially selected aromatic polyamide, it has a high sound velocity and a high internal loss (tan δ). Therefore, since the bending vibration in the high frequency band is reduced, it is possible to prevent split vibration, and it becomes easy to obtain flatness in this band, and a peak is less likely to occur in the high frequency band.

In addition to these features, the acoustic vibration system member of the present invention has the following features:
These preferred characteristics do not change over time, and there is little variation in characteristics. Therefore, good sound quality can be stably obtained.

In addition, it is easy to color the vibration system members, and the design of the subica is excellent.

Furthermore, the acoustic vibration system member of the present invention has excellent moldability; for example, compared to conventionally known para-oriented aromatic polyamide films and polyimide films, it can be hot-press molded at a lower temperature and has a lower molding yield. It is excellent.

Patent applicant: Asahi Kasei Industries, Ltd.

Claims (1)

[Claims] In an acoustic vibration system member formed by hot-pressing a film having a tensile modulus of 900 kg/mm^2 or more into a predetermined shape, the film substantially satisfies the following formula (1) or/and ( 2)
aromatic copolyamide; -NH-Ar_1-NHCO-Ar_2-CO-(1)
-NH-Ar_3-CO-(2) (However, Ar_1 to Ar_3 are Ar_1 to Ar_3
5 to 50 mol% of the total is ▲There are mathematical formulas, chemical formulas, tables, etc.▼ or/and ▲There are mathematical formulas, chemical formulas, tables, etc.▼, and 95 to 50
Mol% is ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ Mathematical formulas ,Chemical formula,
There is a table etc.▼, and 1 selected from the group consisting of these lower alkyl and halogen substituted products.
species or two or more species. ), and has a density of 1.45 to 1.60 g/cm^3.