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The present invention relates to a polyurethane foam for a speaker edge (hereinafter referred to
as a foam for a speaker edge, which is particularly excellent in physical properties such as
strength, elongation, hardness and the like after compression molding). ). The present invention
also relates to a foam for a speaker edge, which is excellent in properties such as moisture heat
aging and ozone resistance deterioration and also has excellent water barrier properties.
2. Description of the Related Art A speaker comprises a cone paper, a voice coil connected to the
cone paper, a voice coil for driving the cone paper, a magnet for driving the voice coil, and a
frame for fixing the magnet. ing. And a speaker edge is a member for connecting cone paper and
a frame, and enabling free vibration of cone paper. At present, as this member, one obtained by
press forming polyurethane foam, one obtained by impregnating a fabric with a resin and
thermoforming it, and one obtained by forming a sheet of rubber or thermoplastic resin are used.
The speaker edge is required to have the following various functions. To be flexible enough not
to interfere with the free vibration of the cone paper, hold the cone paper in place, prevent
contact between the voice coil and the magnet frame, and maintain the linear vibration. It is
flexible in the direction and has rigidity to support the weight of the speaker cone and voice coil
in the lateral direction, and it isolates the sound inside and outside of the speaker box, reduces
the sound circulation effect, and sounds in the low frequency range Low air permeability of the
speaker edge itself in order to improve the pressure and improve the sound quality of the
playback sound of the speaker,
The speaker edge made of polyurethane foam has the various advantages described above and
has the following advantages over the speaker edge made of other materials. Since it is
lightweight and flexible, the reproduction efficiency does not decrease when it is used for a small
aperture speaker. In addition, since the generation of sound from the edge portion is small, it is
possible to obtain good-quality reproduced sound with less noise.
Three-dimensional shaping is possible and can cope with a wide range of amplitudes. Since the
stretchability of the material itself is excellent, there is little deterioration of the sound quality
due to the creep of the edge at the time of high volume reproduction. At the same time, the cone
paper can follow even at the time of high output in the low frequency range, and a large volume
can be obtained even with a relatively small aperture speaker. The hardness, strength and the
like can be easily changed by the compression ratio at the time of compression molding. In
addition, by changing the compression ratio, it is possible to adjust the weight of each member
and the minimum resonance frequency generated due to other variations. Raw materials and
compression molding do not require much cost.
Polyurethane foams are foams obtained using polyester polyols (hereinafter referred to as ester
foams). And a foam obtained using a polyether polyol (hereinafter referred to as an ether-based
foam). There are two types of). And, as a material of the speaker edge, an ester foam is mainly
used. The speaker edge is usually obtained by cutting out a sheet about 10 mm thick from soft
slab foam and compression molding it by a molding machine whose temperature is adjusted to
about 200 ° C., and bonding it to cone paper and a frame to use Be done.
PROBLEM TO BE SOLVED BY THE INVENTION Ester-based foams have fine cells and are
excellent in tensile strength, elongation and the like, and have been widely used as materials for
speaker edges. In particular, the elongation after compression molding is very superior to ether
foams. However, ester-based foams have the major problem of reduced strength due to
hydrolysis of ester bonds due to the polyester polyol used for foam formation. Hereinafter, the
ability to suppress this hydrolysis is referred to as moisture heat aging resistance.
In recent years, audio systems have come to be installed in automobiles, and in particular, longterm durability has been strongly demanded, and conventional ester foams can not be used. In
particular, the adoption of a door structure in which a speaker is installed on the door trim of a
car has recently been increasing. However, moisture such as rain intrudes from between the door
trim and the outer plate, resulting in higher internal humidity than expected. Therefore, it has
become clear that the wet heat deterioration becomes a serious problem when a speaker edge
made of ester type foam is used.
On the other hand, ether foams are very superior to ester foams in terms of hydrolysis. However,
the decrease in strength and elongation due to compression molding is large. In addition, ozone
deterioration is also significantly inferior to ester foams. Therefore, although there is an
advantage of being difficult to hydrolyze and being excellent in wet heat aging resistance, in
reality, ester foams are often used at present. Hereinafter, suppression of the above-mentioned
ozone deterioration is referred to as ozone deterioration resistance.
Furthermore, ether-based foams are said to be resistant to ultraviolet light (hereinafter referred
to as weatherability being capable of suppressing the deterioration of ultraviolet light. ) Is also
inferior to ester foams. Therefore, a speaker using a speaker edge made of ether-based foam can
not be used as an on-vehicle type installed in a rear tray of a car. Further, as described above,
there is intrusion of rain water or the like inside the door, so that the speaker edge is also
required to be waterproof. However, polyurethane foam, which is a porous material, can not
obtain the required waterproofness even if it is heated and compressed, whether it is ester-based
or ether-based.
The following methods have been proposed to solve the above waterproofing problem. Flexible
polyurethane foam (hereinafter referred to as flexible foam). Provide a waterproof film on the
surface of). The flexible foam is impregnated with an emulsion of fluoroplastic and dried to
remove water and form a water repellent foam.
However, it is difficult to form a uniform film having no water permeability on the surface of a
flexible foam in which many micropores are opened. In addition, the material for forming the film
is often low in heat resistance, and the film may be softened, melted and destroyed during heat
compression. Furthermore, this method is expensive. On the other hand, in the method of (1), it is
quite difficult to uniformly impregnate a fluoroplastic emulsion with a flexible foam having low
air permeability in order to enhance waterproofness. Moreover, even if it can be impregnated, it
is difficult to completely remove water from the foam, and the waterproofness tends to be
uneven. Furthermore, the fluororesin emulsion is very expensive, and the resulting foam is
The present invention solves the above-mentioned problems, and by using a polyester polyether
polyol and a specific polymer polyol in combination, a foam for a speaker edge which is excellent
in physical properties such as strength, elongation, hardness and the like particularly after
compression molding. Intended to provide. Further, the present invention is excellent in the
above-mentioned physical properties, and also excellent in heat and moisture aging resistance,
ozone deterioration resistance and weather resistance, and further, has adequate air
permeability, good moldability and excellent stop. It is an object of the present invention to
provide a speaker edge foam having water-based properties.
The foam for a speaker edge according to the first aspect of the present invention is a
polyurethane foam obtained by reacting a composition containing a polyisocyanate and a polyol
component, wherein the polyol component is a polyester polyether polyol, And a polymer polyol
containing a styrene component.
The above-mentioned "polyol component" contains, in addition to various polyols, a foaming
agent, a catalyst, a foam stabilizer and the like.
Moreover, an aromatic secondary amine compound, a terminal monofunctional compound, etc.
can also be mix | blended as needed. Although water is mainly used as a foaming agent,
dichloromethane etc. can also be used together for the purpose of suppression of heat
generation, etc. As the catalyst, usually, an amine-based catalyst, particularly a tertiary amine,
and an organic tin compound such as stannas octoate, dibutyltin diacetate, dibutyltin dilaurate
and the like are used in combination. In addition, as a foam stabilizer, a block copolymer of
general-purpose dimethylpolysiloxane and polyether is used. In addition to this, colorants, fillers
and the like can also be blended.
As said "polyisocyanate", what is generally used for manufacture of a flexible foam can be used
without being restrict | limited in particular. For example, toluene diisocyanate (TDI),
diphenylmethane diisocyanate (MDI) and a mixture of TDI and MDI, or a modified product such
as TDI or MDI can be used. Other than these, aromatic polyisocyanates such as polymeric MDI,
1,5-naphthalene diisocyanate, tolidine diisocyanate, paraphenylene diisocyanate, xylylene
diisocyanate (XDI), tetramethylxylene diisocyanate and lysine diisocyanate can be used. In
addition, aliphatic or alicyclic polyisocyanates such as hexamethylene diisocyanate, hydrogenated
MDI (H12 MDI), isophorone diisocyanate, hydrogenated XDI, and cyclohexyl diisocyanate can
also be used.
As the polyol, "polyester polyether polyol" and "polymer polyol component containing styrene
component" are used in combination. The use of this polyester polyether polyol greatly improves
the strength, the elongation, particularly the elongation after compression molding. Further, the
combined use of the polymer polyol component can further improve the strength and improve
other properties such as hardness. Furthermore, since the polyester polyether polyol has a
polyester portion and a polyether portion in its molecule, the resistance to ozone degradation of
the resulting foam is improved as compared to the ether foam. In addition, heat and humidity
resistance is also improved to the same extent as ether foams.
The polymer polyol component is obtained by graft polymerizing acrylonitrile, styrene or the like
to polyether polyol or the like. In addition to the graft polymer, the polymer polyol component
usually includes polyether polyols and the like not grafted and polymers such as acrylonitrile and
styrene. In the present invention, as the polymer polyol component, one containing at least a
styrene component is used. The styrene component is, as described above, the one obtained by
graft polymerization or the one obtained by polymerization alone. When the total amount of the
graft-polymerized product is a styrene component, it is not preferable because the strength,
elongation and hardness of the resulting foam become insufficient.
In addition, when the total amount of the graft-polymerized product is acrylonitrile, the strength
and the like can be improved, but the foam is thermally decomposed at the time of compression
molding, so that it can not be used. For this reason, as the polymer polyol component,
particularly, as in the second invention, a polymer polyol component having a weight ratio of a
styrene component to an acrylonitrile component of 80/20 to 50/50 is preferable.
In addition, when the solid content in the polymer polyol component is low, it is necessary to
blend a large amount of this polyol in order to sufficiently improve the strength, hardness and
the like of the resulting foam. In that case, the compounding amount of the polyester polyether
polyol has to be reduced, and the improvement of the strength and particularly the elongation
becomes insufficient. Therefore, the solid content in the polymer polyol component is preferably
30% by weight or more when the polymer polyol component is 100% by weight as in the third
The quantitative ratio of the polyester polyether polyol to the polymer polyol component is not
particularly limited. However, in order to improve the strength, elongation, hardness, etc. after
compression molding in a well-balanced manner, it is preferable to set the weight ratio of
polyester polyether polyol to polymer polyol component to about 80/20 to 40/60. . Moreover, as
a polyol, what is normally used for manufacture of a flexible foam can also be used together. For
example, polyester polyol, polyether polyol, etc. can be used in an amount ratio of about 40% by
weight or less, particularly about 30% by weight or less, when the total amount of the polyol is
100% by weight.
As described above, the ozone resistance to aging and the resistance to wet heat aging of the
foam obtained using the polyester polyether polyol are improved. However, this polyester
polyether polyol alone is not particularly resistant to ozone degradation. Therefore, as in the
fourth invention, a specific amount of aromatic secondary amine compound can be blended in
the composition. As a result, it is possible to obtain a foam for a speaker edge having both
excellent ozone deterioration resistance and wet heat aging resistance without particularly using
polyester polyol or polyether polyol in combination.
The above "aromatic secondary amine compound" (hereinafter referred to as "secondary amine
compound"). As phenyl) -naphthylamine, alkylated diphenylamine, N, N'-diphenyl-pphenylenediamine, p- (p-toluenesulfonylamido) diphenylamine, 4,4 '-(α, α-dimethylbenzyl)
Diphenylamine, mixed diallyl-p-phenylenediamine, octylated diphenylamine and the like can be
mentioned. In addition, amine-ketone compounds such as poly (2,2,4-trimethyl-1,2dihydroquinoline) and 6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline are used. It can also be
These secondary amine compounds are used as anti-aging agents such as rubber. However, it is
not known that these compounds have the effect of suppressing the ozone degradation and
hydrolysis of polyurethane foam. When used as an anti-aging agent for rubber, etc., the
compounding amount thereof is usually about several hundred to several thousand ppm and at
most about 5000 ppm with respect to the rubber.
On the other hand, in the present invention, it is blended in a large amount of 1 part by weight or
more, particularly 3 parts by weight or more, and further 5 parts by weight or more with respect
to the polyol. Even if this is converted into the compounding amount with respect to the foam, it
becomes 7,000 ppm or more, particularly 2 parts by weight, further 3.5 parts by weight or more.
Thus, in the present invention, the secondary amine compound is not only known for its action
and effect, but is used in a large amount far exceeding the conventional usual blending amount.
The above secondary amine compounds may be used alone or in combination of two or more. If
the compounding amount of this compound is less than 1 part by weight, the improvement of the
resistance to ozone deterioration and the resistance to wet heat aging is not sufficient. Moreover,
when this compounding quantity exceeds 25 weight part, it is difficult to react and harden a
composition, and a normal foam | form may not be obtained. The amount of the secondary amine
compound is particularly preferably in the range of 1 to 10 parts by weight. With this
compounding amount, a foam for a speaker edge having excellent resistance to ozone
deterioration is obtained, and at the same time, reaction and curing are easy, and there is no
problem in operation, which is preferable.
Further, the addition of this secondary amine compound particularly improves the resistance to
ozone deterioration and also improves the weather resistance. However, in order to further
improve the weather resistance, it is preferable to add a UV absorber. As the UV absorber,
various types such as benzotriazole type, benzophenone type, salicylic acid type and the like can
be used. Furthermore, specific piperidine-based UV absorbers can also be used. The content of
the ultraviolet absorber is preferably about 0.1 to 3% by weight, particularly about 0.5 to 1.5% by
weight, based on 100% by weight of the polyol. The secondary amine compound and the
ultraviolet light absorber may be added in advance to the polyol component or the
polyisocyanate, or may be added simultaneously when the polyol component and the
polyisocyanate are mixed.
As described above, when the foam for a speaker edge according to the present invention is
installed in a door trim of a car, moisture, such as rain water, which intrudes into the interior is a
problem. An indicator of waterproofness required for a speaker edge used for such an on-vehicle
speaker is that there is no water leakage and water permeation for 12 hours or more at a water
pressure of 30 mm. In order to satisfy this required performance, the water absorption measured
by the method described later is 10% or less at 50% compression, 2% or less at 80%
compression, and foam before compression molding (thickness: 10 mm) The air permeability
measured according to JIS L 1096) should be 0.5 to 10 cc / cm 3 · sec, and the air permeability
of the foam after compression molding measured according to JIS P 8117 (Method A) should be
20 seconds or more.
If the water absorption rate of the foam exceeds the upper limit value of each compression rate,
the waterproofness is insufficient and it can not be used as an edge material of a speaker
disposed especially inside a door trim of a car. In addition, since the temperature for compression
molding of the speaker edge foam is a considerably high temperature in view of the heat
resistance of the foam, the molding needs to be performed quickly. When the forming speed is
high, if the air permeability of the foam is too low, the air in the foam cushions to make the
forming difficult, and the obtained speaker edge may be deformed. If the air permeability is too
high, the air permeability will not be sufficiently low even if compressed at a high rate beyond
the practical range, and the waterproofness will be insufficient.
As in the fifth aspect of the invention, it has a hydrocarbon group having 6 or more carbon atoms
at one end or an intermediate part, and the other end contains one active group that reacts with
the isocyanate group contained in the above polyisocyanate, or the above polyol One active
group which reacts with the active hydrogen group contained in the polyol in the component
(these active groups are bonded to the carbon atom at the end of the molecular chain or the
carbon atom next to the carbon atom at the end). By using a composition containing a terminal
monofunctional compound having a), a foam for a speaker edge having excellent waterproofness
as described above can be obtained.
The “hydrocarbon group” of the above “terminal monofunctional compound” may be a
linear group or a branched group, and may be a saturated group or an unsaturated group.
Furthermore, in addition to the aliphatic group, it may contain an aromatic group, an alicyclic
group or these groups. The terminal monofunctional compound may have one of these various
hydrocarbon groups, or may be a mixture of two or more hydrocarbon groups.
The carbon number of the hydrocarbon group is preferably 6 to 48, and more preferably 8 to 36.
These are suitably used in consideration of the required waterproofness, ease of handling, and
the like. Furthermore, as the terminal monofunctional compound, one kind of a compound having
the above “one active group which reacts with an isocyanate group or an active hydrogen
group” may be used, or two or more kinds of various kinds may be used in combination May be
The above-mentioned terminal monofunctional compound means that the above-mentioned
active group is bound to only one of the plurality of molecular terminals of a compound having a
plurality of molecular terminals, For example, -NH-, -O-, -S-, -CO- and -N (R)-(R is an alkyl group.
And compounds having a group such as) are also included. In addition, the carbon number of at
least one of the hydrocarbon groups bonded to both sides of these groups may be 6 or more.
As the terminal monofunctional compound, monoisocyanate such as octadecyl isocyanate or
monoisocyanate derived from a mixture of hexadecylamine and octadecylamine can be used. In
addition, mono-alcohols such as 1-octanol, 1-decanol, lauryl alcohol, oleyl alcohol, other
branched higher alcohols, and monoalcohols having -O-, -S- or the like on the terminal side (for
example, ROCH2-CH2-OH etc.) Alcohol can also be used. Further, octylamine, laurylamine,
octadecylamine and monoamine having -O-, -S- or the like on the terminal side can be
exemplified. In addition, the silicone type foam stabilizer which has a hydroxyl group at the
terminal can also be combined as this terminal monofunctional compound.
The compounding amount of the terminal monofunctional compound is 0.1 to 35 parts by
weight, preferably 0.1 to 25 parts by weight, particularly preferably 0. 25 parts by weight, based
on 100 parts by weight of the total amount of polyisocyanate and polyol. A range of 3 to 10
parts by weight is preferred. The compounding amount is determined by the required
waterproofness in consideration of the carbon number of the hydrocarbon group of the terminal
monofunctional compound to be added, the type of functional group, and the difference in
reactivity with the main component polyisocyanate and polyol. Be done. When the amount is less
than 0.1 parts by weight, sufficient waterproofness can not be obtained. On the other hand, when
the amount is more than 35 parts by weight, it is not preferable because molding of the foam
itself becomes difficult, and properties of the foam originally obtained, such as physical
properties of the resulting foam, are impaired.
Although the waterproofness of the resulting foam is sufficiently excellent by the incorporation
of the terminal monofunctional compound, in order to further improve the waterproofness, the
main components such as polyisocyanate and polyol are also more hydrophobic than the
hydrophilic ones. The sex effect is more waterproof. Further, since it is preferable to increase the
surface area of the foam as much as possible for the waterproof effect to be large, the foam cell is
preferably finer, and the number of cells is preferably 50/25 mm or more, particularly 55/25
mm or more. If the number of cells is less than 50/25 mm, stable water blocking may not be
The terminal monofunctional compound may be blended beforehand with monoalcohol,
monoamine and the like in the polyol component, and monoisocyanate in the polyisocyanate.
Moreover, when mixing a polyol component and polyisocyanate, you may add simultaneously.
Furthermore, since this terminal monofunctional compound has lower reactivity than polyols,
polyisocyanates, etc., it does not inhibit foam formation at all even if it is added after the reaction
start of urethane formation.
BEST MODE FOR CARRYING OUT THE INVENTION Soft slabs are prepared according to a
conventional method using compositions comprising polyisocyanates, polyols, catalysts, foam
stabilizers and the like shown in Tables 1-2 (comparative examples) and Tables 3-5 (examples). I
made a foam. The details of each component are as follows.
(1) Polyol trade name "N2200" (manufactured by Nippon Polyurethane Co., Ltd.): polyester
polyol obtained by condensing diethylene glycol and trimethylolpropane with adipic acid,
hydroxyl value (OHV); 60 trade name "PPG 3000" (manufactured by Sanyo Kasei Co., Ltd.) :
Propylene oxide-based trifunctional polyether polyol starting from glycerin, OHV;56
Trade name "3P56B" (made by Takeda Pharmaceutical Co., Ltd.): 75/70 of polyester polyether
polyol obtained by adding phthalic acid and propylene glycol to trade name "PPG1500" (made by
the same company, polyether polyol) and PPG 3000 mentioned above Mixture of 25 (weight
ratio) ratio, OHV; 56 trade name "FA 728" (manufactured by Sanyo Chemical Industries, Ltd.):
100% by weight of acrylonitrile component polymer polyol, solid content; 30% by weight, OHV;
28 trade name “3445” (manufactured by Mitsui Toatsu Chemicals Co., Ltd.): Polymer polyol
having a styrene component and an acrylonitrile component of 50% by weight, solid content:
20% by weight, OHV;45
Brand name "POP-30" (manufactured by Asahi Denka Kogyo Co., Ltd.): 100% by weight of
polymer component of styrene component, solid content: 20% by weight, OHV; 30 trade name
"CP3943" (manufactured by Mitsubishi Kasei Dow Co., Ltd.): styrene 70% by weight of the
component and 30% by weight of an acrylonitrile-based polymer polyol, solid content; 42% by
weight, OHV;28
(2) Polyisocyanate; trade name “TDI 80” (manufactured by Nippon Polyurethane Industry Co.,
Ltd.) (3) Catalyst: amine-based catalyst manufactured by Nippon Emulsifier Co., Ltd., trade name
“LV33”, metal catalyst manufactured by Johoku Chemical Co., Ltd., Stanus Octoate (SO) (4)
Stabilizers; trade names "L532", "L520" and "SZ1919" (all manufactured by Nippon Unicar Co.,
Ltd.) (5) Secondary amine compounds; trade name "NOCRACK CD" Chemical industry Co., Ltd.
product, 4,4 '-(α, α-dimethylbenzyl) diphenylamine (6) UV absorber; trade name "Sanol LS-744"
(manufactured by Sanko Co., Ltd.), 4-benzoyloxy-2, 2,6,6-Tetramethylpiperidine
A test piece was cut out of the obtained foam for a speaker edge, and the density (kg / m 3), the
25% hardness (g / cm 2) according to JIS K 6401, and the number of cells (piece / 25 mm)
according to JIS K 6402.
Further, tensile strength (kg / cm 2) and elongation (%) were evaluated according to JIS K6301.
Furthermore, air permeability (cc / cm 2 · second) was measured according to JIS L 1096, and air
permeability (second) after compression molding was measured according to JIS P 8117 (method
The water absorption rate, water fastness, wet heat aging resistance, ozone aging resistance and
weather resistance were evaluated by the following methods.
Water absorption rate: A foam of 50 × 50 × 20 (thickness) mm is compressed at a compression
rate of 50% or 80% in the thickness direction, and this compressed test piece is heated at a water
temperature of 23 ° C. and 10 cm below the water surface Measure the increase in weight when
immersed for 24 hours.
The rate of this weight increase is expressed as a percentage based on the volume of the test
piece at 50% compression and at 80% compression. Water absorption rate (%) = [{weight change
before and after immersion (g) / volume of test piece at 50% or 80% compression (cm3)} × 100]
Water-resistant (time): An acrylic resin cylinder with an inner diameter of 30 mm was placed
horizontally, and a speaker edge foam compression-molded at a compression ratio of 14 was
placed on this upper end surface, Place the cylinder in a position corresponding to the lower
cylinder. After that, water in an amount to achieve a water depth of 30 mm is placed inside the
upper cylinder, and the presence or absence of water leakage and water permeation is visually
observed. The goal is that there is no water leakage from the interface between the top surface of
the speaker edge foam and the lower end face of the upper cylinder and no water permeation of
the foam itself after 12 hours.
Moisture resistance to thermal degradation: The tensile strength is measured according to JIS
K6301 at a temperature of 80 ° C. and temperature and humidity controlled to a relative
humidity of 95% for 400, 800, 1600 and 2400 hours of exposure. Ozone resistance: the tensile
strength is measured according to JIS K6301 when exposed to ozone for 200, 400, 600 and 800
hours according to the ozone deterioration test of JIS K6301.
Weather resistance; when exposed to ultraviolet light for 100, 200, 300 and 400 hours at a black
panel temperature of 63 ° C. using an ultraviolet long life fade meter (manufactured by Suga
Test Instruments Co., Ltd., type “FAL-31”) Measure the tensile strength according to JIS
K6301. The above evaluation results are shown in Tables 1 to 5.
According to the results in Tables 1 and 2, the ester foam of Comparative Example 1 is excellent
in the initial tensile strength and elongation of the compressed product and relatively good in
ozone deterioration resistance, but the moist heat aging is It turns out that sex is inferior. On the
other hand, it is understood that although the ether foam of Comparative Example 2 is good in
heat and humidity resistance, the strength and elongation of the compressed product are small,
and the ozone resistance is also inferior. Further, in Comparative Examples 3 to 6 in which the
polyether polyol and the polyester polyether polyol are used in combination, no improvement in
strength and elongation is observed, and improvements in moisture heat resistance and ozone
resistance are not sufficient. Furthermore, as shown in Comparative Examples 7 to 9, it can be
seen that the foam physical properties are not improved at all even if the polyester polyether
polyol is used in combination with a polymer polyol containing only an acrylonitrile component.
On the other hand, according to the results of Tables 3 to 5, in Examples 1 to 6 in which the
polyester polyether polyol and the polymer polyol specified in the present invention are used in
combination, the foam strength and elongation tend to be improved. In particular, in Examples 3
to 4 in which the polymer polyol corresponding to the third invention is used, it can be seen that
an excellent-performance speaker edge foam having both the advantages of ester foam and ether
foam can be obtained. In FIG. 1, the results of wet heat aging of the foams of Comparative
Examples 1 and 2 and Example 4 are shown as a graph. This figure also shows that, in the foam
of Example 4, the initial strength is considerably higher than that of the ether-based foam, and
moreover, the resistance to wet heat aging is also as excellent as that of the ether-based foam.
Further, in Examples 7 to 9 corresponding to the third and fourth inventions, although the
resistance to wet heat aging is equivalent to that in Example 6 etc., the resistance to ozone
deterioration is greatly improved, and the weather resistance is Improvement is also seen. On the
other hand, in Examples 10 to 12 in which the ultraviolet light absorber is blended, the
improvement of the ozone resistance is not observed, but the weather resistance is considerably
improved. Furthermore, Examples 14 and 15 corresponding to the fifth invention (in this case,
the foam stabilizer silicone SZ1919 acts as a terminal monofunctional compound. In the case (1),
the air permeability and the compressive water absorption of the foam are greatly reduced, and
the air permeability of the compressed product is also in the preferable range, and it can be seen
that a foam for a speaker edge excellent in water resistance can be obtained. In this case, as in
Example 15, when the amount of the metal catalyst is increased, the air permeability tends to be
too low, so it is necessary to keep this in mind in compounding.
With regard to the air permeability and air permeability, as shown in Table 6, it is preferable that
the air permeability before compression is in an appropriate range, particularly as in Example 14.
In the case of Comparative Example 1 also, the air permeability and the air permeability are good
results, but when the air permeability is very high as in Comparative Example 2, the air
permeability after compression is too high regardless of the compression rate. (As the air
permeability is 3 seconds or less, the smaller the numerical value, the easier the air is vented),
and the foam becomes inferior in water blocking property.
Also, the air permeability and air permeability of the foam of Example 15 is the lower limit, and
when the air permeability etc. becomes smaller than this, the air in the foam acts as a cushion
and the foam deforms during compression molding. is there. In each comparative example, the
number of cells may be 50/25 mm or less, and the foam cells are relatively large. On the other
hand, in each embodiment, the number of cells is 50/25 mm or more, and in many cases 55/25
mm or more, and the foam cell is relatively small. From this point as well, it can be seen that
stable foams are easily obtained in the speaker edge foam of the present invention.
According to the first aspect of the present invention, the strength and the elongation of the
obtained foam for a speaker edge are improved by using a polyester polyether polyol and a
specific polymer polyol in combination as a polyol. In particular, by using the polymer polyol
specified in the third invention, a foam with higher strength and elongation can be obtained.
Further, according to the fourth invention, the ozone resistance to deterioration of the foam can
be improved by using a specific secondary amine compound. Furthermore, according to the fifth
invention, by blending a specific terminal monofunctional compound, it is possible to greatly
reduce the water absorption rate and the air permeability, and to obtain a foam having an
appropriate air permeability. Thereby, it is possible to obtain a foam for a speaker edge which is
particularly excellent in water blocking properties.
Brief description of the drawings
1 is a graph showing the heat and moisture aging resistance of the foams of Comparative
Examples 1 and 2 and Example 4.
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