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JP2012175678

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DESCRIPTION JP2012175678
The present invention is to provide a composition for a speaker edge having adequate flexibility
and excellent mechanical strength, low temperature adhesion and durability while having
sufficient internal loss. SOLUTION: (A) Polystyrene-hydrogenated polybutadiene-polystyrene
triblock copolymer (a-1), polystyrene-hydrogenated polyisoprene-polystyrene triblock copolymer
(a-2) and polystyrene-hydrogenated Containing at least one kind of 100 parts by mass selected
from butadiene / isoprene copolymer-polystyrene triblock copolymer (a-3), (B) 2 to 30 parts by
mass of polyolefin, and (C) 70 to 300 parts by mass of oil A speaker edge composition
characterized in that the weight average molecular weight of the component (A) is more than
400,000 and not more than 1,000,000 and the pour point of the component (C) is -30.degree. C.
or less . 【Selection chart】 None
Composition for speaker edge
[0001]
The present invention relates to a composition for a speaker edge which has adequate internal
loss, moderate flexibility, and excellent mechanical strength, low temperature adhesion and
durability.
[0002]
The diaphragm of the speaker is supported by the speaker edge.
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Conventionally, urethane foam, paper, cloth, etc. have been used for the speaker edge, but the
speaker edge is not required in that it is required to have a high internal loss so as to be able to
absorb the extra vibration of the diaphragm. It was enough. As a speaker edge material using a
thermoplastic elastomer, for example, a composition containing ethylene-acrylic acid ester
copolymer rubber (see Patent Document 1), a composition containing polyurethane foam (see
Patent Document 2), a styrene system Composition comprising a thermoplastic elastomer based
on a mixture of a thermoplastic elastomer and polypropylene (see Patent Document 3), a
composition comprising an ethylene-propylene-diene compound copolymer rubber (see Patent
Document 4), softening Thermoplastic resin composition forming a matrix phase including a
thermoplastic resin (A) whose point is a certain temperature or more and a polymer (B) whose
internal loss (tan δ) peak temperature is in a certain temperature range (see Patent Document 5)
), (A) Polystyrene-hydrogenated polybutadiene-polystyrene triblock copolymer, polys 100 parts
by mass of at least one selected from triblock copolymers of styrene-hydrogenated polyisoprenepolystyrene and triblock copolymers of polystyrene-hydrogenated butadiene / isoprene
copolymer-polystyrene, (B) polyolefin 2 to 20 The composition (refer patent document 6) etc.
which contain a mass part and 70-300 mass parts of (C) oil are disclosed.
[0003]
JP-A 08-275288 JP-A 08-033095 JP-A 2004-269756 JP-A 11-286567 JP-A 2001-59057 JP-A
2009-65476
[0004]
However, none of the materials described in Patent Documents 1 to 4 have sufficient internal
loss, and if the flexibility is increased to increase the followability to the diaphragm, the
compression set becomes large and the durability is increased. There is a problem that the
acoustic characteristics can not be maintained for a long time because
In addition, the materials described in Patent Document 5 also have insufficient durability and
low temperature adhesion (for example, adhesion at -45 ° C). The materials described in Patent
Document 6 are excellent in internal loss, flexibility and durability, and are suitable for speaker
edge applications, but their mechanical strength and durability have room for further
improvement. The Therefore, an object of the present invention is to provide a composition for a
speaker edge having appropriate flexibility and excellent mechanical strength, low temperature
adhesion and durability while having sufficient internal loss. .
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[0005]
As a result of extensive research to achieve the above object, the present inventors identified (A)
a specific hydrogenated styrenic elastomer, (B) a polyolefin and (C) a specific oil, and specified
each component. It has been found that if the composition is mixed at a ratio, the above problem
can be solved. The present invention has been completed based on such findings.
[0006]
That is, the present invention relates to the following [1] to [8]. [1] (A) Polystyrene-hydrogenated
polybutadiene-polystyrene triblock copolymer (a-1), polystyrene-hydrogenated polyisoprenepolystyrene triblock copolymer (a-2) and polystyrene-hydrogenated butadiene And / or 100
parts by mass of at least one selected from isoprene copolymer-polystyrene triblock copolymer
(a-3), (B) 2 to 30 parts by mass of polyolefin, and (C) 70 to 300 parts by mass of oil And the
component (A) has a weight average molecular weight of more than 400,000 and not more than
1,000,000, and a pour point of the component (C) of -30 ° C. or less. [2] The above-mentioned
[1], wherein the kinematic viscosity at 40 ° C. of the component (C) is 1,000 to 1,500 mm <2> /
s, and the weight average molecular weight is 1,500 to 3,000. The composition for speaker edge
as described. [3] The composition for a speaker edge according to the above [1] or [2], wherein
the component (B) is polypropylene. [4] The composition for a speaker edge according to any one
of the above [1] to [3], wherein the component (C) is a liquid polyolefin oligomer. [5] The
composition for a speaker edge according to the above [4], wherein the liquid polyolefin oligomer
is a copolymer of ethylene and an α-olefin. [6] The composition for a speaker edge according to
any one of the above [1] to [5], further containing (D) polyphenylene ether. [7] For the speaker
edge according to the above [6], wherein the component (D) is at least one selected from
polyphenylene ether / polystyrene based alloy, polyphenylene ether / polypropylene based alloy,
and polyphenylene ether / polyamide based alloy Composition. [8] The composition for a speaker
edge according to the above [6] or [7], wherein a content of the component (D) is 10 to 100 parts
by mass with respect to 100 parts by mass of the component (A).
[0007]
According to the present invention, it is possible to provide a composition for a speaker edge that
has adequate flexibility and has excellent mechanical strength, low temperature adhesion and
durability while having sufficient internal loss. Moreover, the heat resistance of the said
composition can be improved by containing the polyphenylene ether as a component (D) in the
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composition for speaker edges of this invention.
[0008]
In an Example and a comparative example, it is a schematic diagram for demonstrating the
method to evaluate durability of a diaphragm.
[0009]
<Composition for speaker edge> The composition for speaker edge of the present invention is a
triblock copolymer (hereinafter referred to as SEBS) of (A) polystyrene-hydrogenated
polybutadiene-polystyrene described later.
Component (a-1)], polystyrene-hydrogenated polyisoprene-polystyrene triblock copolymer
[hereinafter referred to as SEPS. Component (a-2)] and polystyrene-hydrogenated butadiene /
isoprene copolymer-polystyrene triblock copolymer [hereinafter referred to as SEEPS. It is a
composition which contains at least 1 sort (s) chosen from a component (a-3), (B) polyolefin
mentioned later, and (C) oil mentioned later by a specific ratio.
[0010]
[Component (A)] (Component (a-1): SEBS) As the SEBS, known components can be used as long as
the weight average molecular weight (Mw) exceeds 400,000 and 1,000,000 or less, and there is
no particular limitation. If the weight average molecular weight is 400,000 or less, a composition
having the above-mentioned desired properties can not be obtained. Those having a weight
average molecular weight exceeding 1,000,000 are difficult to obtain. A preferable weight
average molecular weight is more than 400,000 and 800,000 or less, more preferably 410,000
to 600,000, still more preferably 410,000 to 500,000, and particularly preferably 42 to 46,000.
The content of polystyrene block in SEBS is preferably 10 to 70% by mass, more preferably 20 to
65% by mass, and the hydrogenation rate of polybutadiene block is preferably 50% by mol or
more, more preferably 70 to 100 mol %. There is no restriction | limiting in particular about the
manufacturing method of this SEBS, A conventionally well-known method can be used. Moreover,
as SEBS, a commercial item can also be used. In addition, the weight average molecular weight is
gel permeation chromatography (GPC) [Tosoh "HLC-8020", column: Tosoh "GMH-XL" (two in
series), detector: differential refractometer (RI)] The value is obtained in terms of polystyrene of
each polymer based on monodispersed polystyrene, and so forth.
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[0011]
(Component (a-2): SEPS) As SEPS, if a weight average molecular weight (Mw) exceeds 400,000
and is 1,000,000 or less, a well-known thing can be used and there is no restriction | limiting in
particular. If the weight average molecular weight is 400,000 or less, a composition having the
above-mentioned desired properties can not be obtained. Those having a weight average
molecular weight exceeding 1,000,000 are difficult to obtain. A preferable weight average
molecular weight is more than 400,000 and 800,000 or less, more preferably 410,000 to
600,000, still more preferably 410,000 to 500,000, and particularly preferably 42 to 46,000.
The content of polystyrene block in SEPS is preferably 10 to 70% by mass, more preferably 10 to
40% by mass, and the hydrogenation rate of polyisoprene block is preferably 50% by mol or
more, more preferably 70 to 100%. It is mol%. There is no restriction | limiting in particular
about the manufacturing method of this SEPS, A conventionally well-known method can be used.
Moreover, a commercial item can also be used as SEPS.
[0012]
(Component (a-3): SEEPS) As SEEPS, if a weight average molecular weight (Mw) exceeds 400,000
and is 1,000,000 or less, a well-known thing can be used and there is no restriction | limiting in
particular. If the weight average molecular weight is 400,000 or less, a composition having the
above-mentioned desired properties can not be obtained. Those having a weight average
molecular weight exceeding 1,000,000 are difficult to obtain. A preferable weight average
molecular weight is more than 400,000 and 800,000 or less, more preferably 410,000 to
600,000, still more preferably 410,000 to 500,000, and particularly preferably 42 to 46,000.
The content of the polystyrene block is preferably 10 to 70% by mass, more preferably 20 to
40% by mass, and the hydrogenation ratio of the butadiene / isoprene copolymer block is
preferably 50% by mol or more, more preferably 70 to 70%. It is 100 mol%. There is no
restriction | limiting in particular about the manufacturing method of this SEEPS, A
conventionally well-known method can be used. Moreover, a commercial item can also be used as
SEEPS.
[0013]
In the present invention, as the component (A), one of SEBS, SEPS, and SEEPS described above
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may be used alone, or two or more thereof may be used in combination. As the component (A),
SEEPS is preferred from the viewpoint of flexibility, mechanical strength, low temperature
adhesion and durability.
[0014]
[Component (B)] The polyolefin of component (B) is, for example, polyethylene, polypropylene,
ethylene / propylene copolymer, propylene / 4-methyl-1-pentene copolymer, poly (4-methyl-1pentene) , Polybutene-1 and the like. Among them, melt flow rate (hereinafter abbreviated as
MFR) measured according to JIS K 7210 [190 ° C., 21.18 N (2.16 kgf)] from the viewpoint of
processability and heat resistance. It is preferable to use a polyolefin of 0.1 to 100 g / 10 min,
more preferably a polyolefin of 0.5 to 80 g / 10 min, and a polyolefin of 10 to 60 g / 10 min. It is
further preferred to use, and it is particularly preferred to use a polyolefin which is 30 to 60 g /
10 min. Moreover, it is preferable that a component (B) is a polypropylene. Such polyolefins are
commercially available and, for example, "Novatec (registered trademark) BC05B" (trade name,
component: polypropylene, manufactured by Nippon Polypropylene Corporation), "M1600"
(trade name, component: polypropylene, manufactured by Sun Aroma Co., Ltd.) , "Buelon"
(registered trademark, component; polybutene-1, manufactured by Mitsui Chemicals, Inc.), and
the like, and these may be used. The content of the component (B) in the composition for a
speaker edge of the present invention is 2 to 30 parts by mass with respect to 100 parts by mass
of the component (A) from the viewpoint of obtaining the composition having the abovementioned desired properties. And, from the viewpoint of processability, is preferably 5 to 25
parts by mass, more preferably 10 to 25 parts by mass, and still more preferably 10 to 20 parts
by mass.
[0015]
In addition, a polystyrene can be used together to a component (B) in order to improve
processability and heat resistance. As the polystyrene, those obtained by known production
methods can be used, and they may be produced by any of radical polymerization method and
ion polymerization method. The weight average molecular weight of the polystyrene is preferably
5,000 to 500,000, more preferably 10,000 to 200,000, and the molecular weight distribution is
preferably 5 or less. Examples of the polystyrene include polystyrene, styrene-butadiene block
copolymer having a styrene unit content of 60% by mass or more, rubber-reinforced polystyrene,
poly α-methylstyrene, poly p-t-butylstyrene and the like. One of these may be used alone, or two
or more may be used in combination. When using polystyrene together, it is preferable that it is
polyolefin / polystyrene = 95/5-85/15 (mass ratio).
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[0016]
[Component (C)] The oil of component (C) is not particularly limited as long as it has a pour point
of -30 ° C or lower, and, for example, paraffin oil, naphthene oil, silicone oil, aromatic oil, plant
oil Oil or the like can be used. Among these, paraffin oil and silicone oil are preferable from the
viewpoint of compatibility. The pour point can be measured by the method defined in JIS K 2269.
Component (C), particularly paraffinic oil, preferably has a kinematic viscosity at 40 ° C. of
1,000 to 1,500 mm <2> / s, and 1,100 to 1,400 mm from the viewpoint of bleed suppression
and the like. It is more preferable that it is <2> / s, and it is further more preferable that it is
1,100 to 1,300 mm <2> / s. The kinematic viscosity can be measured in accordance with JIS
K2283. Further, the weight average molecular weight (Mw) of the component (C) is preferably
1,500 to 3,000, and more preferably 2,000 to 3,000, from the viewpoint of processability and
bleed suppression. Preferably, it is more preferably 2,200 to 2,600. As a paraffinic oil, for
example, “LUCUANT (registered trademark) HC-100” (trade name, manufactured by Mitsui
Chemicals, Inc., molecular weight: 2,400, dynamic viscosity (40 ° C.): 1,300 mm <2> / s) Etc. As
the naphthenic oil, for example, one having a pour point of −30 ° C. or less among Diana
Process Oil Series manufactured by Idemitsu Kosan Co., Ltd. can be used. As silicone oil, straight
silicone oil and modified silicone oil whose pour point is -30 ° C or less can be used. Examples
of vegetable oils include castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil,
coconut oil, peanut oil, wax, pine oil, olive oil and the like, and the pour point is -30 ° C. The
following can be used: As the component (C), one type may be used alone, or two or more types
may be used in combination as long as the compatibility is good. The pour point of the
component (C) is -30 ° C or less as described above, preferably -30 to -40 ° C, more preferably
-30 to -35 ° C, still more preferably -32 to -35 ° It is C. The content of the component (C) in the
composition for a speaker edge of the present invention is 70 to 300 parts by mass with respect
to 100 parts by mass of the component (A) from the viewpoint of obtaining the composition
having the above-mentioned desired properties. In consideration of flexibility, processability,
mechanical strength, hardness, low temperature adhesion, durability, and suppression of bleed
due to long-term use of the speaker edge, etc., 70 to 270 parts by mass The amount is preferably
70 to 150 parts by mass, more preferably 70 to 120 parts by mass, and particularly preferably
70 to 100 parts by mass.
When the content of the component (C) is less than 70 parts by mass with respect to 100 parts
by mass of the component (A), the hardness of the composition for a speaker edge of the present
invention becomes too high and functions as a speaker edge. It disappears. In addition, when the
content of the component (C) exceeds 300 parts by mass with respect to 100 parts by mass of
the component (A), the hardness becomes too low, and when assembled as a speaker, buffer with
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other parts.
[0017]
In the composition for a speaker edge of the present invention, polyphenylene ether can be
contained as the component (D) as needed for the purpose of improving heat resistance and the
like. [Component (D)] The polyphenylene ether of component (D) has the following repeating unit
[0018]
<img class = "EMIRef" id = "205522897-00002" /> (wherein, R <1>, R <2>, R <3> and R <4> are
each independently a hydrogen atom or halogen Represents an atom, an alkyl group having 1 to
5 carbon atoms, or a phenyl group. Or a copolymer containing the repeating unit, and in the
present invention, it also includes an alloy with polystyrene, polypropylene or polyamide.
[0019]
As a halogen atom which R <1> -R <4> represents in the said repeating unit, a chlorine atom, a
bromine atom, an iodine atom etc. are mentioned, for example. Moreover, as a C1-C5 alkyl group
which R <1> -R <4> represents, a methyl group, an ethyl group, a propyl group, a butyl group, a
pentyl group is mentioned, for example. As the polyphenylene ether, known ones can be used,
and as a homopolymer, for example, poly (2,6-dimethyl-1,4-phenylene ether), poly (2-methyl-6ethyl-1) , 4-phenylene ether), poly (2,6-diphenyl-1,4-phenylene ether), poly (2-methyl-6-phenyl1,4-phenylene ether), poly (2,6-dichloro-1) And 4-phenylene ether). As the copolymer, for
example, 2,6-dimethylphenol and a monovalent phenol (eg, 2,3,6-trimethylphenol or 2-methyl-6butylphenol) And polyphenylene ether copolymers such as copolymers thereof. As the
component (D), for example, commercially available products such as “Zyron (registered
trademark)” manufactured by Asahi Kasei Chemicals Co., Ltd. and “Noryl (registered
trademark)” manufactured by Japan GE Plastics Co., Ltd. can be used. By including the
component (D) in the composition for a speaker edge of the present invention, the heat
resistance of the composition is improved. When the component (D) is contained, the content
thereof is not particularly limited, but it is preferably 10 to 100 parts by mass with respect to
100 parts by mass of the component (A).
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[0020]
[Other Optional Components] In the composition for a speaker edge of the present invention,
other additives may be added in addition to the components (A) to (D) within the range that the
object of the present invention is not impaired. . Examples of such additives include pigments
such as ceramic, carbon black, amber, shenna, kaolin, nickel titanium yellow, cobalt blue,
pramaster gray, quinophthalone, diketopyrrolopyrrole, quinacridone, dioxazine, phthalocyanine
blue, phthalocyanine green, etc. Flame retardant: Antiaging agent: Antistatic agent: Antibacterial
agent: Antioxidant: Talc, silica, calcium carbonate, magnesium carbonate, aluminum hydroxide,
barium sulfate, glass fiber, glass powder, inorganic hollow filler such as glass balloon, ceramic
powder , Inorganic fillers such as mica: organic fillers such as cork powder, wood powder,
graphite etc: release agents such as stearic acid: light stabilizers: tackifiers such as rosin
derivatives (tackifier): "Leostomer (registered trademark) ) B (Trade name, Riken Technos Co.,
Ltd.) adhesive elastomers, such as: coumarone resins, coumarone - indene resins, and phenolic
terpene resins. When such an additive is added, the amount thereof used is preferably 20 parts
by mass or less, more preferably 10 parts by mass or less, per 100 parts by mass of component
(A), and 5 parts by mass It is more preferable that it is the following.
[0021]
[Method of Preparing Composition] There is no particular limitation on the method of preparing
the composition for speaker edge of the present invention, and a conventionally known method
can be adopted, but preparing a pellet-like composition by the following method preferable.
Component (A) to (C) and component (D) and the additive as required are mixed, for example,
using a single-screw kneader, twin-screw kneader, Banbury mixer, Brabender, kneader, high
shear type mixer, etc. The mixture is melt-kneaded at preferably 100 to 300 ° C. (more
preferably 120 to 250 ° C.) to prepare a pellet composition. Here, in order to sufficiently mix
the oil of the component (C) with each component, it is not particularly limited, but it may be
mixed by the following method. For example, a twin screw kneader having a total screw length /
cylinder diameter = 30 or more, preferably 50 to 70, and a ratio of the length of the kneading
zone to the total screw length of 30% or more, preferably 40 to 70% is prepared. A polymer of a
twin-screw kneader prepared by adding a part or all of the component (C) to the components (A)
and (B) and, if necessary, the component (D) and the additive, and mixing them beforehand
Bleeding in which the component (C) is sufficiently mixed into the composition by feeding from
the inlet and, if there is the remaining component (C), melt-kneading by feeding from the
polymer inlet or the side feed port It is possible to obtain difficult pellets. In addition, a part or all
of the component (C) may be simultaneously added to the components (A) and (B) and, if
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necessary, the component (D) and the additive without mixing. It may be fed from a polymer
inlet.
[0022]
The composition of the present invention thus obtained has a hardness (Shore A) of 30 to 55
degrees, preferably 35 to 50 degrees, has appropriate flexibility, and is excellent in
processability. In addition, the glass transition temperature is -60 to -46 ° C, preferably -60 to 48 ° C, more preferably -55 to -48 ° C, and the adhesiveness is also low temperature (for
example, about -45 ° C) Can be maintained. In addition, a molded body obtained by molding the
composition of the present invention has a tear strength of about 6 to 9 N / mm, preferably 7 to
9 N / mm, measured by the method described in the Examples, and mechanical strength
Excellent. Furthermore, the molded article obtained by molding the composition of the present
invention has a number of cracks measured by the method described in the examples of 0 (zero),
and has excellent durability. Therefore, the composition obtained as described above is
particularly suitable as a material for a speaker edge. The composition for a speaker edge
according to the present invention may be formed, for example, by injection molding (molding
conditions: preferably a mold temperature of 30 to 100 ° C., preferably a resin temperature of
150) using the pellet-like composition obtained as described above. C.) and the like.
[0023]
EXAMPLES The present invention will next be described in more detail by way of examples,
which should not be construed as limiting the invention thereto. In addition, the various
characteristics in each case were calculated | required according to the method shown below. (1)
Hardness Shore A hardness was measured according to JIS K6253 (Type A durometer) about the
pellet-like composition prepared by the Example or the comparative example. (2) Internal loss
(tan δ) The pellet-like composition prepared in Example or Comparative Example was injectionmolded under conditions of a mold temperature of 80 ° C. and a resin temperature of 170 ° C.
to measure 40 mm long and 5 mm wide. , 2 mm thick sheet was produced. About this sheet,
using a visco-elastic spectrometer "RDA III" (manufactured by Rheometric Scientific F Co., Ltd.),
measurement of distance between chucks 2 mm, dynamic strain 1%, frequency 1 Hz,
measurement temperature 25 ° C. Under the conditions, the dynamic viscoelasticity
measurement was performed to measure the internal loss (tan δ). (3) Glass transition
temperature (Tg) The pellet composition prepared in Example or Comparative Example was
injection molded under conditions of a mold temperature of 80 ° C. and a resin temperature of
170 ° C. to measure 40 mm long, 5 mm wide, and thickness A 2 mm sheet was made. The
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measurement temperature of this sheet was measured using a viscoelastic spectrometer “RDA
III” (manufactured by Rheometric Scientific F Co., Ltd.) under a measurement condition of a
distance between chucks of 2 mm, a dynamic strain of 1%, and a frequency of 1 Hz. Dynamic
viscoelasticity measurement was performed in the range of −60 to 150 ° C. to measure internal
loss (tan δ). At this time, the measurement temperature when tan δ became the largest was
taken as the glass transition temperature. (4) Tear strength The pellet-like composition prepared
in Examples or Comparative Examples was injection molded under conditions of a mold
temperature of 80 ° C. and a resin temperature of 170 ° C., and a tourer-shaped test piece was
produced according to JIS K6252 The tear strength was measured at a standard test temperature
specified in JIS K6250, and used as an index of mechanical strength. (5) Durability (Number of
Cracks) The pellet-like composition prepared in the example or the comparative example was
injection-molded at a resin temperature of 230 ° C. to produce an edge material for test. Next,
as shown in FIG. 1, the outer frame is fixed to the vibrating portion 4 of the vibrator 3 by the
screw 6 with the diaphragm 1 joined to the test edge material 10 and joined to the test edge
material 10. 2 was fixed to the vibrator base 5. The vibration plate 1 was vibrated with JIS
C5532 noise by the vibrator 3, and after a predetermined time, the number of cracks generated
in the test edge material 10 was observed by an optical microscope.
[0024]
Examples 1 and 2 and Comparative Examples 1 to 8 Each component is mixed in advance
according to the composition shown in Table 1, and then a twin-screw kneader (TEM 58 BS type
manufactured by Toshiba Machine Co., Ltd., total screw length / cylinder diameter = 62.5, The
mixture was kneaded at 180 ° C. at a ratio of the length of the kneading zone to the total screw
length = 62%), and was extruded with a cutter and cut into a strand to prepare each pellet
composition. The various characteristics described above were determined using each pellet-like
composition. The results are shown in Table 1.
[0025]
[0026]
Each component in Table 1 will be described in detail below.
1) "SEPTON 4077": SEPPS, manufactured by Kuraray Co., Ltd., polystyrene-hydrogenated
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butadiene / isoprene copolymer-polystyrene triblock copolymer, weight average molecular
weight about 300,000, polystyrene block content 30 mass% 2) “Septon 4099”: SEEPS,
manufactured by Kuraray Co., Ltd., polystyrene-hydrogenated butadiene / isoprene copolymerpolystyrene triblock copolymer, weight average molecular weight about 440,000, polystyrene
block content 30 mass% 3) “Novatec BC05B ": polypropylene, manufactured by Japan
Polypropylene Corporation, MFR 50 g / 10 min 4)" Diana Process Oil PW 380 ": Paraffin oil, pour
point -15 ° C, kinematic viscosity (40 ° C) 409 mm <2> / s, weight Average molecular weight
750, manufactured by Idemitsu Kosan Co., Ltd. 5) "Lucant HC-100": Paraffin oil, pour point -32.5
° C, dynamic viscosity (40 ° C) 1,300 mm <2> / s, molecular weight 2,400, Mitsui Chemicals,
Inc. 6) "Plastic Master gray ": pigment, made by Dainippon Ink and Chemicals, Inc.
[0027]
From Table 1, it can be seen that the composition for a speaker edge of the present invention has
adequate flexibility while having sufficient internal loss, and is excellent in mechanical strength,
low temperature adhesion and durability. On the other hand, in the composition obtained in
Comparative Example 1, since the weight average molecular weight of the component (A) is
400,000 or less, both the mechanical strength and the durability are low. Similarly, the
composition obtained in Comparative Example 2 also has low durability. In the compositions
obtained in Comparative Examples 3 to 8, the pour point of the component (C) exceeds -30 ° C.,
and the mechanical strength and / or the durability are lowered, and the glass transition
temperature (Tg) is further reduced. ) Is −40 ° C. or higher, and it can be seen that the
adhesion at lower temperatures (about −45 ° C.) is poor.
[0028]
The composition of the present invention, while having sufficient internal loss, has adequate
flexibility and is excellent in mechanical strength, low temperature adhesion and durability, and
is useful as a material for a speaker edge.
[0029]
1 diaphragm 2 outer frame 3 vibrator 4 vibrator 5 vibrator base 6 screw 10 edge material for
test
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