JP2000197184

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DESCRIPTION JP2000197184
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
speaker member. More particularly, the present invention relates to a speaker member
simultaneously having excellent heat resistance, flexibility, moisture resistance, internal loss and
aspect ratio.
[0002]
2. Description of the Related Art Conventionally, various materials such as cloth, resin, elastomer,
rubber and metal foil are known as materials for constituting a speaker member. For example, as
the speaker edge, a polyurethane elastomer or a polyamide elastomer is used. Further, for
example, as a diaphragm for a high frequency speaker (TW), a coating cloth, a polyamide-based
elastomer, or a metal foil is mainly used, and among them, a coating cloth or a polyamide-based
elastomer is used as a diaphragm for a soft dome. ing. These materials can be appropriately
selected according to their properties (that is, according to their purpose), but each has
advantages and disadvantages. For example, polyamide-based elastomers are excellent in heat
resistance and flexibility but have poor rubber elasticity. Moreover, although a polyurethane-type
elastomer is excellent in mechanical strength, the weather resistance and the low temperature
characteristic are inadequate. Thus, for example, heat resistance, weatherability and flexibility are
expected for applications intended to be used in harsh (eg, hot and humid and / or cold)
environments such as automotive audio equipment. In the conventional materials which can not
simultaneously satisfy these characteristics, there is a problem that high quality acoustic
characteristics can not be realized. The coated cloth is formed by coating a urethane resin or an
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acrylic resin on the surface of a cotton fabric impregnated with a phenol resin. Such a coated
fabric is insufficient in moisture resistance because the cotton fabric is made of natural fibers.
Furthermore, the coated fabric is impregnated with a thermosetting resin such as a phenolic
resin, so that the internal loss is small, and as a result, distortion is likely to occur. In addition,
anisotropy occurs because the aspect ratio (MD / CD ratio) increases due to the structure of the
cotton fabric.
[0003]
As described above, a speaker member having simultaneously excellent heat resistance,
flexibility, moisture resistance, internal loss and aspect ratio has not yet been obtained.
[0004]
SUMMARY OF THE INVENTION The present invention has been made to solve the abovementioned conventional problems, and the object of the present invention is to have excellent
heat resistance, flexibility, moisture resistance, internal loss and longitudinal and lateral
dimensions. It is an object of the present invention to provide a speaker member having a ratio
simultaneously.
[0005]
[Means for Solving the Problems] As a result of intensive studies on materials constituting a
speaker member, the present inventors use a thermoplastic elastomer containing a combination
of a hard segment and a soft segment having a specific chemical structure. As a result, it has
been found that a speaker member simultaneously having excellent heat resistance, flexibility,
moisture resistance, internal loss and aspect ratio can be obtained, and the present invention has
been completed.
[0006]
The speaker member of the present invention is formed from an elastomer composition
containing, as a main agent, a thermoplastic elastomer having a hard segment consisting of a
wholly aromatic amide moiety and a soft segment consisting of a polyoxyalkylene moiety.
[0007]
In a preferred embodiment, the above-mentioned elastomer composition further contains a
polyurethane-based thermoplastic elastomer and / or a polyolefin-based thermoplastic elastomer.
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In a preferred embodiment, the elastomer composition contains 20 to 50 parts by weight of the
polyurethane-based thermoplastic elastomer with respect to 100 parts by weight of the
thermoplastic elastomer.
In a preferred embodiment, the elastomer composition contains 5 to 20 parts by weight of the
polyolefin-based thermoplastic elastomer with respect to 100 parts by weight of the
thermoplastic elastomer.
In a preferred embodiment, the polyoxyalkylene moiety is derived from polytetramethylene
glycol.
In a preferred embodiment, the speaker member of the present invention is selected from a
diaphragm, an edge, a voice coil bobbin, a speaker center cap, a speaker frame and a speaker
cabinet.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION The speaker member of the present invention
is formed of an elastomer composition. This elastomer composition is a thermoplastic elastomer
having a hard segment consisting of a wholly aromatic amide moiety and a soft segment
consisting of a polyoxyalkylene ether moiety (hereinafter referred to as an aramid-based
thermoplastic elastomer). ) As a main ingredient. Examples of the amide which forms the abovementioned wholly aromatic amide moiety include poly-p-phenylene phthalamide, poly-pphenylene isophthalamide, and poly-p-phenylene terephthalamide. The polyoxyalkylene moiety is
typically derived from a polyoxyalkylene ether. Representative examples of such ethers include
polytetramethylene ether glycol (PTMG), polypentamethylene ether glycol, and
polyhexamethylene ether glycol. The aramid-based thermoplastic elastomer can be prepared, for
example, by the following procedure. By copolymerizing p-phenylenediamine and a divalent acid
chloride by any appropriate method (for example, the interfacial weight of an aqueous solution of
an amine and a solution of the acid chloride in a water-immiscible solvent under high-speed
stirring conditions) Condensation) gives an amide which forms a wholly aromatic amide moiety.
As the acid chloride, phthaloyl chloride is used to synthesize poly-p-phenylene phthalamide,
isophthaloyl chloride is used to synthesize poly-p-phenylene isophthalamide, and poly-p-
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phenylene terephthalamide is synthesized In the case terephthaloyl chloride is used. Examples of
the non-water miscible organic solvent include benzene and cyclohexanone. The preferred nonwater miscible organic solvent is cyclohexanone. Next, the aramid-based thermoplastic elastomer
is obtained by copolymerizing the above-mentioned amide and polyoxyalkylene ether (preferably,
further with dicarboxylic acid such as terephthalic acid) by any appropriate method (for example,
solution polymerization). can get. This reaction is typically represented by the following reaction
formula.
[0010]
The molar ratio of hard segment to soft segment in the aramid type thermoplastic elastomer is
preferably 60/40 to 80/20. If there are too few hard segments, heat resistance is often
insufficient. If there are too many hard segments, it will be too hard, so the internal loss will be
small. Preferably, the elastomeric composition further contains a polyurethane-based
thermoplastic elastomer and / or a polyolefin-based thermoplastic elastomer. The polyurethanebased thermoplastic elastomer is contained in the elastomer composition in a ratio of preferably
20 to 50 parts by weight, more preferably 30 to 50 parts by weight, with respect to 100 parts by
weight of the aramid-based thermoplastic elastomer. If the content of the polyurethane-based
thermoplastic elastomer is less than 20 parts by weight, the effect of improving the internal loss
often does not appear. If the content exceeds 50 parts by weight, the weather resistance may be
lowered, and the weight of the obtained speaker member will increase. The polyolefin-based
thermoplastic elastomer is contained in the elastomer composition in a proportion of preferably
5 to 20 parts by weight, and more preferably 10 to 20 parts by weight with respect to 100 parts
by weight of the aramid-based thermoplastic elastomer. If the content of the polyolefin-based
thermoplastic elastomer is less than 5 parts by weight, the effect of improving the internal loss
often does not appear. If the content is more than 20 parts by weight, the compatibility and
adhesion with the aramid-based thermoplastic elastomer often decrease.
[0011]
If necessary, the elastomer composition may further contain an antioxidant, an ultraviolet light
stabilizer, a colorant, a filler and the like. The content of these additives may be appropriately set
depending on the purpose. The member for a speaker of the present invention makes the abovementioned elastomer composition into any appropriate shape (for example, cone shape, dome
shape, edge shape) by any appropriate method (for example, extrusion molding, injection
molding, heat press molding) It is obtained by molding. For example, when the present invention
is applied to a diaphragm for a speaker, the above-mentioned elastomer composition is formed
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into a sheet by extrusion, and then this sheet is molded into a mold having a predetermined
shape (for example, cone shape, dome shape) Heat press molding using Also, for example, when
the present invention is applied to a speaker edge, a procedure similar to that of the diaphragm
may be adopted except that a mold having a predetermined edge shape is used. As extrusion
conditions and heat press conditions, any appropriate conditions may be adopted depending on
the purpose.
[0012]
The speaker member of the present invention includes a diaphragm, an edge, a voice coil bobbin,
a speaker center cap, a speaker frame and a speaker cabinet. Particularly preferred applications
of the inventive speaker member are diaphragms and edges.
[0013]
Hereinafter, the operation of the present invention will be described. According to the present
invention, a thermoplastic elastomer (aramid-based thermoplastic elastomer) having a hard
segment consisting of a wholly aromatic amide moiety and a soft segment consisting of a
polyoxyalkylene moiety is used. Such aramid-based thermoplastic elastomers have a high melting
point and a low glass transition point due to their chemical structure. That is, the aramid-based
thermoplastic elastomer has a high melting point because the hard segment has a rigid allaromatic amide structure, and has a low glass transition point because the soft segment has a
polyoxyalkylene structure. Therefore, since the member for speakers obtained has a very wide
rubber elastic region, it is excellent in heat resistance and excellent in flexibility (embrittle
resistance) at low temperature. Moreover, the aramid thermoplastic elastomer is lightweight.
Therefore, the resulting speaker member is lightweight and highly elastic, and has high acoustic
characteristics because vibrations from the drive system are linearly transmitted. As a result, it is
possible to obtain a speaker member capable of maintaining high acoustic characteristics even in
applications used in a harsh (for example, high temperature and humidity and / or cold)
environment such as in-vehicle acoustic devices.
[0014]
In addition, since the aramid thermoplastic elastomer has a high degree of crystallinity (about
60%; for example, a polyamide of 20 to 30%), the water absorption is low (that is, excellent in
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moisture resistance). Furthermore, since the aramid thermoplastic elastomer has high phase
separation between the hard segment and the soft segment, the strength MD / CD ratio is small,
and deformation during molding is prevented.
[0015]
In a preferred embodiment, an aramid-based thermoplastic elastomer and a polyurethane-based
or polyolefin-based thermoplastic elastomer are used in combination. By using the aramid
thermoplastic elastomer in combination with the polyurethane or polyolefin thermoplastic
elastomer, the internal heat resistance is improved while maintaining the excellent heat
resistance, flexibility, moisture resistance and aspect ratio of the aramid thermoplastic elastomer.
It can be done. That is, the polyurethane-based or polyolefin-based thermoplastic elastomer can
reflect its own excellent internal loss to the speaker member without impairing the
characteristics of the aramid-based thermoplastic elastomer. As a result, in the member for a
speaker obtained, generation of abnormal noise can be suppressed at the time of high volume,
and clear sound quality can be achieved.
[0016]
EXAMPLES The present invention will be explained specifically by the following examples, but
the present invention is not limited to these examples.
[0017]
EXAMPLE 1 p-phenylenediamine was dissolved in water.
Meanwhile, phthaloyl chloride was dissolved in cyclohexanone. The resulting two solutions were
mixed with high speed stirring, and the mixed solution was heated with stirring. Interfacial
polycondensation was performed while maintaining this state to obtain poly-p-phenylene
phthalamide. The resulting poly-p-phenylene phthalamide was gradually dissolved in
concentrated sulfuric acid and this solution was mixed with polytetramethylene ether glycol.
Terephthalic acid was added to the resulting mixture and heated. Solution polymerization was
carried out by maintaining this state to obtain an aramid thermoplastic elastomer. The resulting
aramid thermoplastic elastomer was pelletized. Such aramid thermoplastic elastomers are
commercially available from Tosoh. An elastomer composition is prepared by adding 5 parts by
weight of an antioxidant, 2 parts by weight of an ultraviolet light stabilizer, and 1 part by weight
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of carbon black to 100 parts by weight of aramid thermoplastic elastomer pellets, and using an
extrusion molding machine, It was formed into a sheet under the conditions shown in Table 1.
The obtained sheet was hot press-molded under the conditions shown in the following Table 1
using an edge mold of a predetermined shape to obtain an edge for a speaker.
[0019]
The density ρ, the melting point Tm, the glass transition temperature Tg, the elongation at
break, and the internal loss tan δ of the obtained edge were measured by a conventional
method. The results are shown in Table 2 together with the results of Examples 2 to 3 and
Comparative Example 1 described later.
[0021]
Example 2 The same procedure as in Example 1 was carried out except that 30 parts by weight
of polyurethane thermoplastic elastomer (Elastolan black ET 593-10, manufactured by Takeda
Burdiche Urethane Co., Ltd.) was added to the elastomer composition. The speaker edge was
obtained. The obtained edge was subjected to the same measurement as in Example 1. The
results are shown in Table 2.
[0022]
Example 3 A speaker edge was obtained in the same manner as in Example 2 except that the
amount of the polyurethane-based thermoplastic elastomer added was 50 parts by weight. The
obtained edge was subjected to the same measurement as in Example 1. The results are shown in
Table 2.
[0023]
Comparative Example 1 A polyamide-based thermoplastic elastomer having a hard segment
consisting of an aliphatic polyamide (Diamide-PAE, manufactured by Daicel-Huls, Ltd.) was used
instead of the aramid-based thermoplastic elastomer, and heat press A speaker edge was
obtained in the same manner as in Example 1 except that the temperature was set to 170 to 180
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° C. The obtained edge was subjected to the same measurement as in Example 1. The results are
shown in Table 2. As apparent from Table 2 above, the edges of Examples 1 to 3 have high Tm
and low Tg (that is, a wide elastic region) as compared with the edges of Comparative Example 1.
As a result, the edge of Examples 1 to 3 is significantly superior to the edge of Comparative
Example 1 in breaking elongation. Furthermore, as apparent from the results of Examples 2 and
3, the addition of the polyurethane-based thermoplastic elastomer can improve the internal loss
(that is, improve the acoustic properties) while maintaining excellent elongation at break. It
becomes possible.
[0024]
Example 4 A loudspeaker diaphragm was obtained in the same manner as in Example 1 except
that a diaphragm mold having a predetermined shape was used. The internal loss, the aspect
ratio of strength (MD / CD ratio), and the water absorption were measured for the obtained
diaphragm. The results are shown in Table 3 together with the results of Examples 5 to 8 and
Comparative Examples 2 to 3 described later.
[0026]
EXAMPLE 5 A loudspeaker diaphragm was obtained in the same manner as in Example 2 except
that a diaphragm mold having a predetermined shape was used. The obtained diaphragm was
subjected to the same measurement as in Example 4. The results are shown in Table 3.
[0027]
Example 6 A speaker diaphragm was obtained in the same manner as in Example 3 except that a
diaphragm mold having a predetermined shape was used. The obtained diaphragm was subjected
to the same measurement as in Example 4. The results are shown in Table 3.
[0028]
(Example 7) A diaphragm for a speaker in the same manner as in Example 5 except that 10 parts
by weight of a polyolefin-based thermoplastic elastomer (manufactured by Mitsubishi Resins Co.,
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Ltd., Thermolan) was used instead of 30 parts by weight of a polyurethane-based thermoplastic
elastomer. I got The obtained diaphragm was subjected to the same measurement as in Example
4. The results are shown in Table 3.
[0029]
(Example 8) A speaker diaphragm was obtained in the same manner as in Example 7 except that
the amount of the polyolefin-based thermoplastic elastomer added was 20 parts by weight. The
obtained diaphragm was subjected to the same measurement as in Example 4. The results are
shown in Table 3.
[0030]
Comparative Example 2 A speaker diaphragm was obtained in the same manner as Comparative
Example 1 except that a diaphragm mold having a predetermined shape was used. The obtained
diaphragm was subjected to the same measurement as in Example 4. The results are shown in
Table 3.
[0031]
Comparative Example 3 10 parts by weight of phenol resin was impregnated with 100 parts by
weight of cotton fabric, and 5 parts by weight of acrylic resin was coated as an undercoat, and 10
parts by weight of urethane resin was coated as a top coat. This coated cloth was heat-pressed
for 10 seconds at 180 ° C. and 350 kgf using a diaphragm mold of a predetermined shape to
obtain a diaphragm for a speaker. The obtained diaphragm was subjected to the same
measurement as in Example 4. The results are shown in Table 3. As is apparent from Table 3
above, the diaphragms of Examples 4 to 8 are both superior in the aspect ratio of the strength
and the water absorption rate than the diaphragms of Comparative Examples 2 and 3. From this,
it can be seen that according to the diaphragm of the present invention, there is no deformation
at the time of molding and no deformation due to humidity, and no gap failure occurs.
Furthermore, as is apparent from the results of Examples 5 to 8, the addition of the polyurethane
or polyolefin thermoplastic elastomer improves internal loss while maintaining excellent aspect
ratio and water absorption (that is, acoustic characteristics). Can be improved).
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[0032]
(Example 9) The amount of the polyurethane thermoplastic elastomer added to the elastomer
composition was changed, and in the same manner as in Example 4, an edge for a speaker was
produced. The relationship between the addition amount of the polyurethane-based
thermoplastic elastomer and the internal loss (tan δ) was examined. The results are shown in the
graph of FIG.
[0033]
Example 10 The edges of Examples 4 to 6 and an edge formed of a polyurethane thermoplastic
elastomer alone were subjected to a humidity deterioration test. The humidity degradation test
was performed by measuring the time-dependent change of the tensile strength retention under
the conditions of a temperature of 60 ° C. and a relative humidity of 95%. The results are shown
in the graph of FIG. As shown in FIGS. 1 and 2, in consideration of the balance between the
internal loss and the weather resistance, the amount of the polyurethane-based thermoplastic
elastomer added is in the range of 20 to 50 parts by weight with respect to 100 parts by weight
of the aramid-based thermoplastic elastomer. It is understood that is preferable.
[0034]
Example 11 The amount of the polyolefin thermoplastic elastomer added to the elastomer
composition was changed, and in the same manner as in Example 4, an edge for a speaker was
produced. The relationship between the addition amount of the polyolefin-based thermoplastic
elastomer and the internal loss (tan δ) and the Young's modulus E (dyn / cm 2) was examined.
The results are shown in the graph of FIG. As shown in FIG. 3, in consideration of the balance
between the internal loss and the Young's modulus, the addition amount of the polyolefin-based
thermoplastic elastomer is preferably in the range of 5 to 20 parts by weight with respect to 100
parts by weight of the aramid-based thermoplastic elastomer. I understand.
[0035]
According to the present invention, by using an aramid thermoplastic elastomer, a speaker
member simultaneously having excellent heat resistance, flexibility, moisture resistance, internal
loss and aspect ratio can be obtained.
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