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JP2007295239

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DESCRIPTION JP2007295239
[PROBLEMS] To provide a resin molded body for acoustic equipment parts having vibration
suppression / noise control characteristics, acoustic characteristics, dimensional accuracy, heat
resistance, and surface smoothness. An amorphous thermoplastic resin is contained, and a loss
coefficient (η) of a secondary resonance peak measured by a half value width method in one end
fixed steady vibration method at 23 ° C is 0.02 or more. The resin molding for acoustic devices
formed by shape ¦ molding a resin composition. 【Selection chart】 None
Resin molding for audio equipment
[0001]
The present invention relates to a resin molded body for an audio device such as a speaker for
home appliances, automobiles and the like.
[0002]
Metal, wood, paper, resin, etc. are used as materials for audio equipment such as home
appliances such as audio equipment, game consoles and radios, and audio equipment such as
speakers such as audios for vehicles and videos. It is most common to use resin-made moldings
for reasons of freedom, lightness and the like.
[0003]
The parts for these audio equipment are required to have damping for sound quality
improvement, noise control characteristics and acoustic characteristics, dimensional accuracy,
heat resistance that can withstand high temperature atmosphere in the car, and more excellent
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surface appearance. At present, molded articles made of polypropylene resin, ABS resin, PBT
resin, modified polyphenylene ether resin, polycarbonate resin and the like are used.
[0004]
In Patent Documents 1 and 2, a resin composition in which a specific glass fiber and an inorganic
filler are mixed with a polypropylene resin is used for a speaker frame, and a resin composition
in which mica is mixed in a polymer alloy of a polyphenylene ether resin and a polyamide resin.
Has been disclosed for use in molded articles for acoustic devices, but it is not sufficient in
particular in terms of dimensional accuracy and surface appearance.
[0005]
Further, Patent Document 3 discloses a speaker diaphragm in which an inorganic filler is blended
in a polymer alloy of polyphenylene ether resin and polystyrene resin.
The speaker diaphragm disclosed in Patent Document 3 satisfies the required performance such
as dimensional accuracy, heat resistance, and surface appearance, and has high performance.
However, the demand for parts for acoustic devices has recently been increased. In terms of
vibration damping, noise control characteristics and acoustic characteristics, it can not be said
that they have sufficient performance.
[0006]
Therefore, at present, there is an increasing demand for parts for acoustic devices that have
damping / noise control characteristics, acoustic characteristics and dimensional accuracy, heat
resistance, and surface smoothness.
[0007]
JP-A-2001-119791 JP-A-9-302222 JP-A-2006-33024
[0008]
An object of the present invention is to provide a resin molded body for acoustic device parts
having both vibration suppression and noise control characteristics, acoustic characteristics,
dimensional accuracy, heat resistance, and surface smoothness.
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[0009]
As a result of intensive studies to solve the above problems, the present inventors have found
that the above problems can be solved when a specific resin composition containing an
amorphous thermoplastic resin is used as a material. The present invention has been made.
[0010]
That is, the resin molded article for acoustic devices of the present invention contains an
amorphous thermoplastic resin, and the loss coefficient of the secondary resonance peak
measured by the half-width method in one-end fixed steady-state vibration method at 23 ° C. It
is characterized in that it is formed by molding a resin composition having a η) of 0.02 or more.
[0011]
The resin molded product for audio equipment of the present invention has damping and noise
control characteristics and acoustic characteristics, as well as dimensional accuracy, heat
resistance, and surface smoothness, and the performance of the audio equipment such as
household appliances and speakers for automobiles etc. It greatly contributes to the
improvement.
[0012]
In the present invention, the resin molded product for audio equipment refers to a speaker
casing, a speaker frame, a speaker bottom plate, a speaker horn, an equalizer, and the like used
for audio equipment such as speakers used in home appliances, game machines, personal
computers, automobiles and the like. It says generically and resin parts such as diaphragm and
speaker grille.
[0013]
The resin composition used in the present invention contains an amorphous thermoplastic resin,
and the loss coefficient (η) of the secondary resonance peak measured by the half-width method
at 0 ° C. in 23 ° C. in the fixed-fixed steady-state excitation method is 0. Or more, preferably
0.03 or more, and more preferably 0.03 to 0.09.
If the loss factor is 0.02 or more, parts having excellent vibration control, noise control
characteristics and acoustic characteristics can be obtained, and sound quality improvement such
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as a speaker becomes possible.
In addition, a loss coefficient said here can be measured by the method of JISG0602-1993, using
a 127 mm x 12.7 mm x 3.2 mm strip test piece as a test piece.
[0014]
The resin composition used in the present invention preferably has a deflection temperature
under load of 90 ° C. or higher measured under a stress of 1.82 MPa according to ASTM-D648.
When the deflection temperature under load is 90 ° C. or higher, it is possible to obtain a
component which does not cause thermal deformation even in a high temperature environment
such as the inside of a car.
[0015]
The amorphous thermoplastic resin contained in the resin composition used in the present
invention includes, for example, polystyrene resin, rubber reinforced polystyrene resin (high
impact-polystyrene resin), styrene resin such as ABS resin; polycarbonate resin, polycarbonate
resin / Polycarbonate resins such as ABS resin alloy, polycarbonate resin / polybutylene
terephthalate resin alloy: Modified polyphenylene ether resin (polyphenylene ether resin and
polystyrene resin, or alloy of high impact polystyrene resin), polyphenylene ether resin /
polypropylene resin alloy, Polyphenylene ether resin such as polyphenylene ether resin /
polyphenylene sulfide resin alloy can be used.
Among these, polycarbonate resins and polyphenylene ether resins are preferable, and
polyphenylene ether resins are more preferable in terms of heat resistance, dimensional
accuracy, surface appearance, and weight reduction.
[0016]
The resin to be contained other than the amorphous thermoplastic resin is not particularly
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limited, but a block copolymer composed of a vinyl aromatic compound polymer block and a
conjugated diene compound polymer block (hereinafter, "block copolymer") And polyolefin
compounds are preferable because they can improve the loss factor.
Specifically, the following compositions (1) and (2) can be mentioned as preferable examples.
[0017]
(1) A resin composition comprising 97 to 70 parts by weight of an amorphous thermoplastic
resin and 3 to 30 parts by weight of a block copolymer.
[0018]
(2) A resin composition comprising 96.9 to 50 parts by weight of an amorphous thermoplastic
resin, 3 to 30 parts by weight of a block copolymer, and 0.1 to 20 parts by weight of a polyolefin
compound.
[0019]
Here, as a vinyl aromatic compound which comprises the vinyl aromatic compound polymer
block of a block copolymer, 1 type, or 2 or more types are chosen from styrene, alphamethylstyrene, vinyl toluene etc., for example, Styrene is particularly preferred.
In addition, as the conjugated diene compound constituting the conjugated diene compound
polymer block, for example, one or more selected from isoprene, butadiene, 1,3-pentadiene etc.,
among which isoprene and butadiene are preferable, and isoprene is preferable. Particularly
preferred.
[0020]
The mass ratio of the vinyl aromatic compound polymer block to the conjugated diene compound
polymer block (vinyl aromatic compound polymer block / conjugated diene compound polymer
block) of the block copolymer is preferably 5/95 to 60/40. And more preferably 10/90 to
30/70.
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When the mass ratio of the vinyl aromatic compound polymer block exceeds 60%, the loss factor
may not be sufficiently increased. Conversely, if it is less than 5%, the compatibility with the
amorphous thermoplastic resin to be a matrix becomes a matrix. May deteriorate and mechanical
properties may drop.
[0021]
In addition, the conjugated diene compound polymer block portion of the block copolymer is
preferably selectively hydrogenated to an extent that the degree of unsaturation does not exceed
60% from the viewpoint of thermal stability, and the degree of unsaturation is It is particularly
preferable to be hydrogenated to 20 to 50%.
[0022]
The content of the block copolymer is 3 to 30 parts by weight, preferably 4 to 20 parts by
weight, and more preferably 5 to 15 parts by weight in the resin component.
If the content of the block copolymer is less than 3 parts by weight, the loss factor may not be
sufficiently increased, and if it exceeds 30 parts by weight, the mechanical strength may be
reduced.
[0023]
Examples of polyolefin-based compounds include homopolymers of olefin-based monomers such
as polyethylene, polypropylene, polybutylene and polyisobutylene, and co-polymers containing
olefin-based monomers such as ethylene-propylene-based copolymers and ethylene-ethylene
acrylate-based copolymers. Although a polymer can be mentioned, a polypropylene and an
ethylene-propylene type copolymer are preferable.
[0024]
The content of the olefin-based compound is 0.1 to 20 parts by weight, preferably 3 to 15 parts
by weight, and more preferably 5 to 10 parts by weight in the resin component.
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When the content of the olefin compound exceeds 20 parts by weight, there is a possibility that
the mechanical strength is lowered and the surface of the molded article is peeled off.
[0025]
When the amorphous thermoplastic resin is a polyphenylene ether resin, a block copolymer
comprising a conjugated diene monomer unit and a vinyl aromatic monomer unit having a
coupling structure is hydrogenated. Hydrogenated copolymer which is obtained by
hydrogenating a (non-hydrogenated) random copolymer block consisting of a conjugated diene
monomer unit and a vinyl aromatic monomer unit. A hydrogenated copolymer having a
copolymer block (hereinafter referred to as "hydrogenated copolymer").
) Is also preferable because it can improve the loss factor.
Specifically, the following composition (3) is mentioned as a preferable example.
[0026]
(3) A resin composition comprising 70 to 95 parts by weight of a polyphenylene ether resin and
5 to 30 parts by weight of a hydrogenated copolymer.
[0027]
The content of the hydrogenated copolymer is 5 to 30 parts by weight, preferably 7 to 25 parts
by weight, more preferably 10 to 20 parts by weight in consideration of the balance between the
improvement of the loss factor and the mechanical strength.
[0028]
The resin composition used in the present invention is 2 to 40 parts by weight, preferably 10 to
30 parts by weight of at least one of talc and clay per 100 parts by weight of resin when rigidity
and strength are required of parts. You may contain in part.
By strengthening with talc and clay, a molded article with good surface smoothness can be
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obtained.
If the content of talc and clay is less than 2 parts by weight, the rigidity and strength may hardly
be improved, and if it exceeds 40 parts by weight, the material may become brittle and the
surface smoothness may also be reduced.
The average particle size of talc used is preferably 20 μm or less, and the average particle size of
clay is preferably 1.0 μm or less.
[0029]
The resin composition used in the present invention is blended with additives which are added to
conventional thermoplastic resins as required, such as heat stabilizers, UV absorbers, flame
retardants, mold release agents, lubricants, dyes, pigments and the like. There is no particular
restriction on what to do.
[0030]
Although the resin composition used by this invention can be adjusted using conventionally wellknown techniques, such as a bra bender, a kneader, a Banbury mixer, an extruder, it is preferable
to adjust using an extruder.
[0031]
The resin molded article for acoustic devices of the present invention can be obtained by molding
by a known molding method such as general injection molding, injection press molding, gas
injection molding and the like.
In addition, the surface decoration such as painting on the molded article is not particularly
limited.
[0032]
Hereinafter, the present invention will be described in detail based on examples, but the present
invention is not limited by these examples.
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[0033]
The components used in the examples and comparative examples are as follows.
[0034]
(1) Amorphous thermoplastic resin 1) Polyphenylene ether resin Poly 2,6-dimethyl-1,4phenylene ether 2) High impact, which has an intrinsic viscosity [η] of 0.52 (30 ° C. in
chloroform) -Polystyrene resin "PSJ polystyrene H9405", manufactured by PS Japan 3)
Polystyrene resin "PSJ polystyrene 685", manufactured by PS Japan 4) Polycarbonate resin
"Panlite K-1300", manufactured by Teijin Chemicals Ltd.
[0035]
(2) Block copolymer Hydrogenated styrene-isoprene block copolymer ("HYBLER 7125",
manufactured by Kuraray Co., Ltd.)
[0036]
(3) Polyolefin-based compound Polypropylene resin ("Novatec PP EA9BT" manufactured by
Nippon Polypropylene Co., Ltd.)
[0037]
(4) Hydrogenated copolymer <Preparation of hydrogenation catalyst> A hydrogenation catalyst
used for a hydrogenation reaction was manufactured as follows.
[0038]
Into a nitrogen-substituted reaction vessel, 2 liters of dried and purified cyclohexane was
charged, and 40-poly (bis (.eta.-cyclopentadienyl))-di-p-tolyl titanium and 1,2-polybutadiene (1,1
having a molecular weight of about 1,000) After dissolving 150 g of 2-vinyl bond content, add a
cyclohexane solution containing 60 mmol of n-butyllithium, react for 5 minutes at room
temperature, immediately add 40 mmol of n-butanol and stir The hydrogenation catalyst was
obtained by carrying out.
[0039]
<Preparation of Hydrogenated Copolymer> Copolymerization was carried out according to the
following method using a stirrer with an internal volume of 10 liters and a jacketed tank reactor.
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[0040]
After 10 parts by weight of cyclohexane is charged into the reactor and adjusted to a
temperature of 80 ° C., 0.076% by weight based on the weight of all monomers (total amount of
butadiene monomer and styrene monomer charged into the reactor) And a cyclohexane solution
containing 22 parts by weight of N, N, N ', N'-tetramethylethylenediamine in an amount of 0.4
mol with respect to 1 mol of n-butyllithium and then 11 parts by weight of styrene as a monomer
Was added over about 6 minutes, and reacted for 30 minutes while adjusting the temperature in
the reactor to about 80.degree.
[0041]
Next, a cyclohexane solution (monomer concentration 22% by weight) containing 33 parts by
weight of butadiene and 56 parts by weight of styrene was continuously fed to the reactor at a
constant rate for 60 minutes.
During this time, the temperature inside the reactor was adjusted to about 80 ° C. to obtain a
copolymer.
The styrene content of the obtained copolymer was 67% by weight, the content of the styrene
polymer block was 11% by weight, and the vinyl bond content of the butadiene portion was 18%
by weight.
[0042]
Next, 0.6 mol of dimethyldichlorosilane was added to 1 mol of n-butyllithium used for the
obtained copolymer, and coupling reaction was performed for 10 minutes.
[0043]
Furthermore, 100 weight ppm of titanium as the above-mentioned hydrogenation catalyst was
added with respect to the weight of the copolymer, and the hydrogenation reaction was
performed at a hydrogen pressure of 0.7 MPa and a temperature of 65 ° C.
[0044]
After completion of the reaction, methanol is added, and then octadecyl-3- (3,5-di-t-butyl-4-
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hydroxyphenyl) propionate as a stabilizer is added at 0.3% by weight based on the weight of the
polymer, A hydrogenated block copolymer was obtained.
[0045]
The weight average molecular weight of the obtained hydrogenated block copolymer was
200,000, the hydrogenation rate was 99%, and the peak temperature of tan δ (loss tangent) was
10 ° C.
Moreover, as a result of differential scanning calorimetry (DSC measurement), there was no
crystallization peak.
[0046]
(5) Talc "HITRON A", manufactured by Takeuchi Chemical Industry Co., Ltd.
[0047]
(6) Flame Retardant Aromatic phosphate ester flame retardant
Co., Ltd.
CR741
, Daihachi Chemical
[0048]
<Examples 1 to 8 and Comparative Examples 1 to 3> A twin-screw extruder ("ZSK-40"
manufactured by WERNER & PFLEIDERE, in which each component of the composition shown in
Table 1 is set to a temperature of 290 to 320 ° C and a screw rotation speed of 500 rpm The
mixture was melt-kneaded in accordance with the above to obtain resin composition pellets.
[0049]
Using this pellet, injection molding is performed at a cylinder temperature of 280 to 300 ° C
and a mold temperature of 60 to 100 ° C, and a test piece for evaluating the physical properties
of the composition and a speaker horn simulated molded article shown in FIG. Various tests were
conducted by the following methods.
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The evaluation results are shown in Table 1.
[0050]
(1) Physical Properties of Composition 1) Loss Coefficient η Measured in accordance with JIS
G0602-1993.
[0051]
That is, using a loss factor measurement device (manufactured by Matsushita Intertechno Co.,
Ltd.) at 23 ° C., a test piece (a strip test piece of 127 mm × 12.7 mm × 3.2 mm) is subjected to
electromagnetic vibration by a steady state fixed excitation method at one end. The response
speed was read to obtain the transfer function.
Next, the frequency at a point 3 dB below the absolute value of the secondary resonance peak
was read, and the loss factor η was determined from the half width method.
[0052]
2) Deflection temperature under load Measured according to ASTM D-648 (load: 1.82 MPa).
[0053]
3) Specific gravity Measured in accordance with ASTM D-792.
[0054]
4) Flexural modulus Measured according to ASTM D-790 (23 ° C.).
[0055]
(2) Evaluation of Molded Article The following characteristics were evaluated for the speaker
horn simulated molded article.
[0056]
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1) Sound quality evaluation (damping and noise reduction characteristics, acoustic
characteristics) The molded product was incorporated into an actual speaker, and the sound
quality was evaluated after assembly, and evaluated according to the following criteria.
◎: The sound quality is very good.
○: Sound quality is good.
Δ: General sound quality.
[0057]
2) Warpage The warpage of the molded product was visually evaluated and evaluated according
to the following criteria.
○: Warpage can not be confirmed.
Fair: slight warpage can be confirmed.
X: The warp can be clearly confirmed.
[0058]
3) Heat resistance The molded articles were visually evaluated for deformation after being left in
an oven at 80 ° C. for 24 hours, and evaluated according to the following criteria.
○: The deformation can not be confirmed.
Fair: some deformation can be confirmed.
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X: The deformation can be clearly confirmed.
[0059]
4) Surface smoothness (surface appearance) The surface smoothness of the molded product was
visually evaluated, and evaluated according to the following criteria.
◎: Surface roughness such as filler floating can not be confirmed at all, and the surface condition
is very good.
○: Surface roughness such as filler floating can hardly be confirmed and surface condition is
good.
X: Surface roughening can be clearly confirmed due to filler floating, and surface condition is
poor.
[0060]
[0061]
As shown in Table 1, it can be seen that the molded article of the present invention has both
sound quality, dimensional accuracy, heat resistance, and surface smoothness.
[0062]
On the other hand, in the molded articles of Comparative Examples 1 and 3 in which the resin
composition having a loss factor of less than 0.02 was used, no improvement in the sound quality
was observed.
Moreover, although the molded product of Comparative Example 2 using the resin composition
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containing no amorphous thermoplastic resin was found to have the effect of improving the
sound quality, it was insufficient in terms of warping and heat resistance of the molded product. .
[0063]
The resin molded product for audio equipment of the present invention has damping and noise
control characteristics, acoustic characteristics, dimensional accuracy, heat resistance, and
surface smoothness, and is used for home appliances, game machines, personal computers,
automobiles, etc. It is possible to improve the performance of parts such as a speaker housing, a
speaker frame, a speaker bottom plate, a speaker horn, an equalizer, a diaphragm, a speaker grill,
and the like that are used for audio equipment such as speakers.
[0064]
It is a figure which shows the shape of the speaker horn simulation molded article used for
evaluation in the Example.
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