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JPH0492599

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DESCRIPTION JPH0492599
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
acoustic vibration system member molded of a resin film, and more particularly to an acoustic
vibration system member having remarkably improved acoustic performance. [Prior Art] A
vibration system member for sound includes a diaphragm, a voice coil bobbin, a center cap, a
suspension (edge, damper, etc.), etc. In terms of the diaphragm, a resin film has recently been
molded. It is used, and a film of polyester, polypropylene, polyether sulfone, polyimide or the like
is thermoformed into a predetermined shape. However, these resin films conventionally used
have the following disadvantages. That is, since the above-mentioned conventional films have few
high speed of sound propagation (hereinafter referred to as "sound velocity"), moreover, they
have small internal loss (hereinafter referred to as r tan δ) and easily resonate in the used
frequency band Many things get worse. In addition, although a polypropylene film or the like
having a large tan δ may be used, those having a large tan δ have a low sound velocity and
have a low high-frequency reproduction limit frequency. As a film having a large sound velocity,
an aromatic polyamide film is known. For example, JP-A-63-278491, JP-A-1-78496 and JP-A-1135297 disclose aromatic polyamide films. An acoustic vibration system member is disclosed.
And these have the characteristics that the reproduction | regeneration band of sound is wide
and distortion by division vibration is small. However, while the vibration-based members
described in these prior art examples have the above-mentioned characteristics, they have poor
creep resistance and often have subtle changes in the characteristics of the sound after molding,
and coloring Dissatisfaction remained that it was inferior to design because it was difficult to
SUMMARY OF THE INVENTION The object of the present invention is to eliminate the drawbacks
of the above-mentioned conventional acoustic vibration system members and to use the aromatic
copolyamide 'film of a special chemical composition, so that the speed of sound is extremely fast.
In addition, it is an object of the present invention to provide an acoustic vibration system
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member which has a large internal loss, does not change or disperse its characteristics with time,
and is further excellent in design with easy coloring. (Means for Solving the Problems) As a result
of earnest studies to solve the problems, it has been found that excellent vibration-based acoustic
members can be provided by using an aromatic copolyamide film having a specific ether bond.
The present invention has been made based on the findings. That is, according to the present
invention, in the vibration-based acoustic member formed by heat-pressing a film having a tensile
modulus of 900 kg /-or more into a predetermined shape, the film substantially has the following
formula (1) or / and (2) Aromatic copolyamide; NHArt NHCOArz CO (1) NHAr ,, co (2) (where Ar
1-Ar 3 is 5 to 50 mole% of the total of Ar, ~ A, r 3 but Xφ> -@ <-Or / and one or more selected
from the group consisting of alkyl and halogen substitution products.
And 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 having a large tensile
elastic modulus has a large sonic elastic modulus at -C, and the speed of sound in the film is
large, and the usable frequency range as a vibrating member is broadened. The tensile modulus
of the film is preferably at least 1000 kg / lII. The film used in the present invention consists
essentially of an aromatic copolyamide, but it is important that the aromatic copolyamide
contains a specific ether bond. That is, the film of the present invention is substantially an
aromatic polyamide of the following formula (1) or / and (2); -NH-A, r, -NHCO-Arz-CO- (1) NH-Ar,CO- (2) (wherein A r 1 to A r 3 is one or more selected from the group consisting of 5 alkyl and
halogen substitution products in total of A r + to A r 3). )からなっている。 Although it is known
to use a film made of an aromatic polyamide having the same homogeneity as a high sound
velocity acoustic diaphragm, the so-called aromatic copolyamide film containing a specific
amount of a specific ether bond of the present invention is unique It turned out that it has a
property. That is, while maintaining the inherent high sound velocity and high internal loss of the
rose-oriented aromatic polyamide film, these characteristics do not change at all over time, and
the coloring is facilitated, which is excellent for design. It was found to be a vibration system
member. Such a preferred feature is that the introduction of ether bonds imparts a suitable
flexibility to the loosely arranged aromatic copolyamides having a rigid molecular structure,
thereby reducing the residual stress in the hot-pressed molding, Because of this, it is assumed
that the characteristics change or become less variable. Also, the ease of coloring is considered to
be related to the ease of molecular movement. The vibration-based vibration member of the
present invention is formed by hot pressing of a specific film, and the film needs to have a
density of 1.45 to 1.60 g / afl. Such densities belong to relatively high levels for aromatic
polyamides. That is, they have structural features such as high crystallinity and / or halogen
substitution and high electron density. Such a feature is one of the requirements for high sound
velocity despite the fact that the aromatic polyamide used in the present invention is a
copolymer.
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In the present invention, as heat pressure molding, for example, the film is press molded with a
mold heated to at least 200'C, and the mold is cooled to an appropriate temperature as it is in a
pressed state and then demolded. It can be molded. The vibration system members for sound in
the present invention include diaphragms for speakers, microphones and earphones, center
camps for speakers, voice coil bobbins for speakers and suspensions for speakers, and edges, etc.
Alternatively, two or more parts to be adjacent to each other may be integrally formed. In
addition, the vibration co-member having a laminated structure can also be obtained by bonding
the aromatic copolyamide film of the present invention in advance with an adhesive and
thermoforming it. The vibration system member of the present invention has excellent
characteristics such as tan δ (internal loss) of at least 2800 m / sec and an internal loss of 0.03
or more, and these characteristics are also under various environments over time. But it hardly
changes. In addition, glass fibers, carbon fibers, carbon particles, carbon whiskers, talc, silica, etc.
may be added to adjust the surface property, moldability, and acoustic properties, and voids are
contained by adopting a foaming method or the like. You may The film used in the present
invention can be produced, for example, by the method disclosed in JP-B-57-17886, JP-A-5284245, JP-A-56-104937 and the like. EXAMPLE 1 Example 1 is an example of forming a coneshaped diaphragm. The female mold is heated to 250 ° C. using a male and female press mold
provided with a cooling medium passage, and the tensile modulus is 1030 kg with a thickness of
about 38 μm. A cone-shaped diaphragm was obtained by press-forming a film of / mj,
elongation 5 o%, density 1.50 g / aa, sound velocity 3000 va / sec, and jan 60.046. This film is
an aromatic copolyamide having the following chemical structure: When 10 speakers were made
from the obtained diaphragm and frequency characteristics of this speaker were created, no
difference was found among the 10 speakers, and there was no change after leaving for about 1
month. Comparative Example 1 As in Example 1, a cone-shaped diaphragm was made of a film
having the following characteristics. The film used had the following chemical structure, and had
a thickness of about 38 μm, a tensile modulus of 1200 kg / mj, an elongation of 40%, a density
of 1.50 g / cJ, a speed of sound of 3100 m1 sec, and a tan δ of 0.032.
In molding, the female mold was heated to 380 ° C. and the male mold was heated to 300 ° C.
As in the example, a frequency characteristic diagram was created, but there was a slight
difference between the five speakers, and when it was measured again one month later, a slight
shift toward the low frequency side was observed. A film is formed from the aromatic
copolyamide having the chemical structure of Example 2 by a wet method, and the film in a
water-containing state before drying is an organic containing 5% by weight of cationic dye Gui
Acrylic Red GLN (made by Mitsubishi Chemical Industries, Ltd.) The film was immersed in a
solvent for 5 minutes to contain the dye and then stretched and dried to obtain a red film. This
film has a thickness of 50 μm, a tensile modulus of elasticity of 950 kg / d, an elongation of
90%, a density of 1.45 g / ci, a speed of sound of 2800 m / sec, an an δ of 0.039 and a 0 film. It
was press-molded with a mold heated to an a-type 230 ° C. to obtain a dome-shaped diaphragm.
The diaphragm had a bright red color. Comparative Example 2 The film used in Comparative
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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 therefrom were almost the same as in Comparative Example 1, but the obtained diaphragm
is black to red, and has a poor appearance. The [Effect of the Invention] Since the vibration-based
vibration member of the present invention is made of a specially selected aromatic polyamide,
the sound velocity is large and the internal loss (tan δ) is also large. For this reason, since the
flexural vibration in the high frequency band is reduced, the divided vibration can be prevented,
and it becomes easy to obtain the flatness of this band and it becomes difficult to generate a peak
in the high frequency band. In addition to these characteristics, the vibration-based vibration
member of the present invention is characterized in that such preferable characteristics do not
change with the passage of time, and that the variation of the characteristics is small. Therefore,
good sound quality can be obtained stably. In addition, the coloring of the vibration system
member is easy, and the design as a SVIKA is excellent. Furthermore, the vibration-based acoustic
member of the present invention is excellent in moldability, and can be hot-pressure molded at a
low temperature, for example, as compared to conventionally known para-oriented aromatic
polyamide films and polyimide films. It is excellent. Patent applicant Asahi Kasei Kogyo Co., Ltd.
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