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JPS58137395

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DESCRIPTION JPS58137395
[0001]
The present invention relates to a method of manufacturing a speaker diaphragm mainly
composed of a thermoplastic resin, and an object of the present invention is to provide a method
of manufacturing a speaker diaphragm which is capable of mass production by enabling
continuous sheet production. It is in. In general, a paper cone has often been used for the speaker
diaphragm. This is due to the low density of the paper cone (about 0.69 / ca) and moderate
modulus and internal loss, density is efficiency (sound pressure). The distortion and the input
resistance, the elastic modulus is related to the reproduction frequency band, and the internal
loss is related to the flatness of the frequency characteristic. In recent years, attempts have been
made to use metal materials such as aluminum and polyethylene, and polymer materials such as
polyethylene and polypropylene as materials to replace paper cones, but metal materials have a
high elastic modulus, but their density is high. Moreover, since the internal loss is also small, the
application is almost limited to the tweeter. On the other hand, although the polymer material
has a high internal tA loss, it is mainly used only for the woofer because the elastic modulus is
low. In order to replace the paper cone, a material having a low density, a high elastic modulus,
and a large internal loss is desired. In particular, among polymer materials, thermoplastic resins
can be produced by continuous sheets, and non-woven fabrics composed mainly of these
thermoplastic resin fibers can contain a large amount of air layers in the diaphragm itself as a
molded product by thermoforming It can be said that it is an advantageous material in addition
to low density. However, the non-woven fabric mainly composed of thermoplastic resin fibers is
simply an aggregate of fibers itself, and there is a phenomenon that spring banking occurs after
thermoforming, so that it is difficult to repeat thermoforming for reproducibility. . The present
invention solves such conventional defects, and thermoforming is carried out with a heated mold
of a non-woven fabric mainly composed of thermoplastic resin fibers to which fibers are fixed by
a heat fusion method, and then 1 -The compounding mold is cooled and the diaphragm molded
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into a predetermined shape is taken out. After thermoforming a non-woven fabric mainly
composed of the thermoplastic resin rim m and then cooling the die of the thermoforming dam
and then taking out a diaphragm as a molding, the spring bank of the non-thermoformed nonwoven fabric can be prevented The area density can be kept constant. In addition, since the nonwoven fabric mainly composed of thermoplastic resin fibers is fixed by the heat melting method
prior to the thermoforming, the spring bank is in a state of being suppressed in advance during
the thermoforming. In preventing the later spring bank, it is possible to greatly reduce the
variation in surface density, Ii.
Therefore, the production method of the present invention has the advantage of being able to
achieve low density reproducibly and continuously. Here, the non-woven fabric may be prepared
by any method such as a wet method, a direct method such as pan bond method, or a dry method
such as card type or random universal type, but heat fusion method The fiber must be fixed.
Other methods of fixing fibers of non-woven fabric include an adhesive method, needle punch
method, slat method, etc. In these methods, the surface density of the non-woven fabric itself
becomes uneven, which means that it is in thermoforming. Since the spring back can not be
sufficiently suppressed, variations in the surface density of the diaphragm itself occur.
Hereinafter, examples of the present invention will be described. [Example 1] A carded nonwoven
fabric comprising 20 wt% of 2 deniers, 6 adII of fiber length (KevLar-29 manufactured by
Dupont) and 2 deniers, 80 wt% of 2 deniers, 6 length of curled polyethylene terephthalate fibers
Made by a non-woven fabric manufacturing machine. And, fixation of the fiber was performed
through a 180-220'C heat roll. Here, as shown in FIG. 1, the card type non-woven fabric
manufacturing machine loosens the raw material fibers by using a measuring wire machine,
mixes them with a cotton blender, and supplies this from the feeder 1 to the feeder 2 to transfer
it. The machine 2 is configured to transfer it to the rotary comb-like 3 and 4 to catch the fibers to
make a sheet (web), and the above-mentioned rotary comb-like 3 and 4 has the cylinder 5 and
the fanci 6 as shown in FIG. , Woofer 7, stripper 8 and the like. The web prepared by such a nonwoven fabric manufacturing machine was subjected to fixing of fibers by passing it through a
heat roll 9 as shown in FIG. The non-woven fabric thus produced was molded into a diaphragm of
10 cm in diameter with a molding die 12 ° 13 having band heaters 10 and 11 for heating on
the outer periphery as shown in FIG. The mold temperature at this thermoforming is suitably
180 to 240 'C. If it is 180' C or less, deformation due to Sugelinda back occurs, and if it is 240 C
or more, the polyester fiber is completely melted and molds 12, 13 Therefore, the temperature
was set at 22 ° C. The diaphragm thermoformed by the molding die 12.13 was carried out after
the cooling water was passed through the cooling pipes 14.15 provided on the dies 12, 13 at the
time of removal thereof to make the die temperature 80 'C or less. In the case of thermoforming,
the non-woven fabric sheet was slightly heated beforehand by the far-infrared heater 16. As
described above, if preheating is performed in advance to the thermoforming, the formability at
the time of thermoforming with the forming dies 12-13 can be improved.
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In addition, when the molding die 12.13 is cooled after the thermoforming, it is possible to
prevent the springback of the formed diaphragm, that is, the non-woven fabric. Physical
properties of the non-woven fabric composed of the above-mentioned aramid fiber and polyester
fiber are shown in the following table. In addition, as apparent from the table of diameter 1 Qcm
using the diaphragm made as described above, the nonwoven fabric of this example has a density
of o, tsey / r, f 9 'and an elasticity ratio of 2, 5 x 1010 dyn / cJ. Specific modulus is 4, 46 'X I C)
10c! / 5 ec2, the internal loss is 0.068, and it shows excellent physical property value compared
to the conventional paper cone, and a speaker with a diameter of 1 ocrlL using a paper cone of
the same weight as apparent from FIG. 5 The reproduction frequency band is wider than the
above, and its frequency characteristics are flat and low in distortion. In FIG. 5, A indicates the
sound pressure frequency characteristic of the present embodiment, B indicates the conventional
sound pressure frequency characteristic, C indicates the second-order distortion characteristic of
the present embodiment, and D indicates the conventional second-order distortion characteristic.
. The content of aramid fibers affects the modulus of elasticity and the formability of the nonwoven fabric mixed with polyester fibers. Therefore, the content of aramid fibers must be
determined appropriately in consideration of these. FIG. 6 shows the relationship between the
aramid fiber content and the elastic modulus. It can be seen from FIG. 6 that the content of
aramid fibers is not very effective at 10 wt% or less. Further, at 30 wt% or more, the elastic
modulus becomes low F and the aramid fiber does not stretch, which causes a problem in
formability. Therefore, as a content rate of an aramid fiber, 10 to 30 wt% is desirable. As
described above, in the physical properties of the speaker diaphragm made of the non-woven
fabric of the present embodiment, the density is almost as low as that of the paper, and the
internal loss and the elastic modulus are high. It is also excellent in water resistance and heat
resistance, and can be produced by continuous sheets instead of sheet-by-sheet forming like
conventional paper cones in mass productivity. The adhesion was also good because the surface
of the sheet was rough. [Example 2] A non-woven fabric comprising 20 wt% of 2 deniers, curled
aramid fibers of 6 fiber lengths and 6 wt% of 2 deniers, 80 wt% of curled methylpentene polymer
fibers of 5 m in fiber length It is made by the card type non-woven fabric manufacturing machine
described above. And fixation of the fiber was performed through a 180-220'C heat roll. The
non-woven fabric thus produced was thermally formed under the same conditions as in Example
1 using the molding die 12.13 described above. Then, the temperature of the molding die was 80
C or less (2 C), and the molded product and the t-C diaphragm were extracted by IIM.
In the case of thermoforming, the non-woven fabric sheet was preheated beforehand with a far
infrared heater. The nonwoven fabric of this example has a density of Q 2, a 60 S '/' CJ N elastic
modulus of 2.3 × 10 4 clyn / crl, a specific elastic modulus of 4.6 × 10 10 cr I / 5 e C 2 and an
internal loss of 0.070. As is apparent from FIG. 7, the reproduction frequency band is wider and
the frequency is wider than a speaker of diameter 1 ocWL using a paper cone of the same
weight, as shown in FIG. The characteristics are also flat and low Φ. In FIG. 7, A indicates the
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sound pressure frequency characteristic of the present embodiment, B indicates the conventional
sound pressure frequency characteristic, C indicates the second-order distortion characteristic of
the present embodiment, and D indicates the conventional second-order distortion characteristic.
. As described above, according to the present invention, a mold formed by heating a non-woven
fabric mainly made of thermoplastic resin fibers to which fibers are fixed by heat fusion is
thermally formed, and then 1-blending type is cooled. Since the diaphragm molded into a
predetermined shape is taken out, it is physically superior to conventional paper cones, and it
reproduces a speaker diaphragm with high efficiency, a wide operating frequency band and low
distortion. It can be manufactured sexually continuously.
[0002]
Brief description of the drawings
[0003]
1 is a block diagram of a non-woven fabric manufacturing machine for a speaker diaphragm
according to the present invention, FIG. 2 and FIG. 3 are enlarged views of main parts of the
same manufacturing machine, and FIG. Explanatory drawing of the thermoforming process of a
board, FIG. 5 is a comparative characteristic view of the speaker diaphragm of one embodiment
of the present invention and the conventional speaker diaphragm, and FIG. 6 is aramid fiber in
the speaker diaphragm of the present invention. FIG. 7 is a characteristic curve of a speaker
diaphragm according to another embodiment of the present invention and a conventional
speaker diaphragm according to the present invention.
12, 13, ..., molding dies, 10, 11, ...,. ヒータ。 Name of Agent Attorney Nakao Toshio and 1 other
person Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 15 Fig. 5 Fig. 15 Fig. 1-<and (// Z116 Fig. 1 entry 1 · Korea 4
shoulder Prison (wt stain)
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