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JPH118897

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DESCRIPTION JPH118897
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
polyurethane foam speaker edge which is particularly excellent in cold resistance and acoustic
characteristics and excellent in physical properties such as strength, elongation and hardness.
Furthermore, the present invention relates to a polyurethane foam speaker edge having
properties such as good heat and humidity aging and ozone resistance deterioration.
[0002]
A speaker comprises a cone paper, a voice coil connected to the cone paper, a voice coil for
driving the cone paper, a magnetic circuit comprising a magnet and a plate for driving the voice
coil, and the magnetic circuit It is comprised by the frame for fixing. 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.
[0003]
The speaker edge is required to have the following various functions. Be flexible enough not to
disturb the free vibration of the cone paper. In order to hold the cone in place, prevent contact
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between the voice coil and the magnetic circuit, and to maintain linear vibration, it is flexible in
the longitudinal direction and in the lateral direction the speaker cone and voice coil. Have
rigidity to support weight. The air permeability of the speaker edge itself is low to isolate the
inside of the speaker box and the outside, reduce the sound circulation effect, improve the sound
pressure of the low frequency range, and improve the sound quality of the reproduced sound of
the speaker. Lightweight to increase sound pressure. This weight reduction makes it possible to
reduce the size of the magnet, which is advantageous in cost. Also, in the case of the same
magnet, the sound pressure is high and the volume is high.
[0004]
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.
[0005]
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.
[0006]
Polyurethane foam is a foam obtained by using a polyester polyol (hereinafter referred to as
"ester foam". And a foam obtained using a polyether polyol (hereinafter referred to as "etherbased 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
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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.
[0007]
SUMMARY OF THE INVENTION An ester foam is excellent in physical properties such as tensile
strength and hardness and in moldability and the like, and a speaker edge excellent in acoustic
characteristics can be obtained. However, there is a problem that the strength is reduced due to
hydrolysis of the ester bond, that is, so-called moisture heat aging resistance is poor. On the
other hand, although ether foams are excellent in this moist heat aging resistance, they are
inferior in weather resistance, ozone deterioration resistance and the like, and also tend to be
inferior in acoustic characteristics as compared with ester foams. The cause of the sound quality
deterioration is presumed to be that the material strength is low, which causes an increase in
edge resonance, a deterioration in followability at large input, and the like.
[0008]
As described above, each of the ester-based foam and the ether-based foam has problems caused
by its chemical structure, and development of a foam having the advantages of both foams is
desired. In JP-A-8-33095, by using a polyester polyether polyol having an ester group and an
ether group in one molecule, a speaker edge having excellent weather resistance and moisture
resistance and good sound quality can be obtained. ,Have been described.
[0009]
However, the cold resistance is not always good at this speaker edge. That is because the abovementioned polyester polyether polyol is obtained by reacting an anhydride of an aromatic
polycarboxylic acid with a cyclic ether group, and has an aromatic polycarboxylic acid residue in
its molecule. That is, it is considered that polarization is likely to occur because an ester group,
which is a polar group, is bonded next to the aromatic ring. Moreover, its main chain is located in
a plane, and it has a rigid molecular structure by the repetition of aromatic ring and ester group,
and it is considered that the cold resistance is so good because there are few molecular chains
that can move at low temperature. Absent.
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[0010]
By the way, with regard to the cold resistance of the speaker edge, the necessity is particularly
increased due to the change of the following situation. That is, in recent years, audio systems
have come to be installed in automobiles, and their durability has been strongly demanded. Then,
a speaker mounted on a rear tray or the like at the rear of the rear seat at the beginning is often
attached particularly to a door trim. In this case, the speaker is susceptible to the ambient air
noise, and in particular, if a large volume of reproduced sound is sent to the speaker after
parking for a long time in winter, a load is rapidly applied to the speaker edge, resulting in
acoustic characteristics or durability. It has become clear that major problems such as decline
occur.
[0011]
The present invention solves the above-mentioned problems, and uses a high molecular weight
polyether polyol for improving cold resistance. However, that alone does not improve the
acoustic characteristics. Therefore, polymer polyols are used to improve foam hardness and
improve acoustical properties. In the present invention, by combining the specific polyether
polyol and the polymer polyol in this way, a speaker edge made of polyurethane foam is provided
which is excellent in cold resistance and acoustic characteristics and also has good weather
resistance, moisture resistance and the like. The purpose is to
[0012]
A speaker edge made of polyurethane foam according to the first aspect of the present invention
is a speaker edge made of polyurethane foam obtained by reacting a composition containing a
polyisocyanate and a polyol component, wherein the polyol component has a molecular weight
of It is characterized in that it contains a 3500 to 9,000 polyether polyol and a polymer polyol
component containing a styrene component.
[0013]
As said "polyisocyanate", what is generally used for manufacture of a flexible foam can be used
without being restrict | limited in particular.
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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. Besides, aromatic
polyisocyanates such as polymeric MDI, 1,5-naphthalene diisocyanate, tolidine diisocyanate,
paraphenylene diisocyanate, xylylene diisocyanate (XDI) and tetramethylxylene diisocyanate can
be used. In addition, aliphatic or alicyclic polyisocyanates such as hexamethylene diisocyanate,
hydrogenated XDI (H6 XDI), hydrogenated MDI (H12 MDI), isophorone diisocyanate, cyclohexyl
diisocyanate and lysine diisocyanate can also be used.
[0014]
As the above-mentioned "polyol component", a "polyether polyol" having a high molecular weight
of "average molecular weight 3500 to 9000" and a "polymer polyol component" containing a
"styrene component" are used in combination. The molecules of this polyether polyol are linear
and have a movable structure. As a result, the cold resistance of the resulting foam is improved,
and moreover, the high molecular weight causes little decrease in strength. In addition, the
combined use of the polymer polyol component further improves the strength and also improves
other properties such as hardness.
[0015]
As this high molecular weight polyether polyol, it is a normal polyether polyol which the alkylene
oxide added to alcohol, amines, ammonia etc., Comprising: Especially high molecular weight thing
can be used. Examples of alcohols include monohydric alcohols such as methanol, ethanol and
butanol, and dihydric alcohols such as ethylene glycol, propylene glycol and 1,6-hexanediol. In
addition, trihydric alcohols such as glycerin and trimethylolpropane, tetrahydric alcohols such as
pentaerythritol and methylglucoxide, pentahydric alcohols such as 2,2,6,6-tetrakis
(hydroxymethyl) cyclohexanol, and sorbitol And hexavalent alcohols such as sucrose and the like.
[0016]
Furthermore, examples of amines include monovalent amines such as dimethylamine and
diethylamine, and divalent amines such as methylamine, ethylamine and aniline. Further,
trivalent amines such as monoethanolamine, diethanolamine and triethanolamine, tetravalent
amines such as ethylenediamine and hexamethylenediamine, and pentavalent amines such as
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diethylenetriamine can also be mentioned. Furthermore, as the alkylene oxide, ethylene oxide
(hereinafter abbreviated as "E0"), propylene oxide (hereinafter abbreviated as "PO"), 1,2-, 1,4- or
2,3-butylene oxide Etc. can be mentioned. One of these alkylene oxides may be used alone, or two
or more thereof may be used in combination. Particularly preferred alkylene oxides are EO and
PO, and those obtained by adding ethylene and propylene moieties in block or random are
preferable.
[0017]
As the high molecular weight polyether polyol, one having an average functional group number
of “2.0 to 4.0” and a hydroxyl value of “20 to 50” is particularly preferable as in the second
invention. The hydroxyl value is more preferably in the range of 25 to 45, particularly 30 to 45.
Further, as this polyether polyol, it is preferable to use polyhydric alcohols such as glycerin and
trimethylolpropane as alcohols and to which PO is added, or to which PO and EO are added in a
block or at random or the like. It is.
[0018]
When the average number of functional groups is less than 2.0 or the hydroxyl value is less than
20, the cells become unstable at the time of foaming and it becomes difficult to produce a foam.
On the other hand, when the average number of functional groups is more than 4.0 or the
hydroxyl value is more than 50, the cells become closed cell at the time of foaming and the foam
may be shrunk to fail to obtain a normal foam. Furthermore, the foam tends to be too hard and
the cold resistance tends to decrease. Further, the content of the oxyethylene unit in the high
molecular weight polyether polyol is preferably 20% by weight or less, particularly 10% by
weight or less. When the content of the oxyethylene unit exceeds 20% by weight, the resulting
foam becomes hydrophilic, and the speaker edge is likely to absorb water, and further, the
crystallinity becomes high and the cold resistance is lowered, which is not preferable.
[0019]
The polymer polyol component is obtained by graft-polymerizing vinyl monomers such as
acrylonitrile and methyl methacrylate in addition to styrene to polyether polyol and 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 styrene and acrylonitrile. In the present invention,
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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.
[0020]
When the total amount of graft-polymerized products 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
third invention, a polymer having a weight ratio of a styrene component to an acrylonitrile
component of 80/20 to 50/50, particularly 80/20 to 60/40. Polyol components are preferred.
[0021]
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 blending amount of polyether polyol has to be
reduced, and the improvement of the cold resistance 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.
[0022]
The main object of the present invention is to improve the cold resistance of the obtained
speaker edge, but the polyurethane foam constituting this speaker edge has a glass transition
point (Tg) of “-as in the sixth invention. Those having a temperature of 30 ° C. or less,
particularly −35 ° C. or less are preferable. By using a foam with a low Tg in this manner, the
speaker edge can be made less susceptible to embrittlement even at low temperatures, without
loss of flexibility, and deterioration of acoustic characteristics at low temperatures can also be
suppressed.
[0023]
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Furthermore, in the present invention, as in the fourth invention, the polyol component is
referred to as a "hydroxy compound having an ether bond and an ester bond in one molecule"
(hereinafter referred to as a "specific hydroxy compound"). ) Can also be contained. As this
specific hydroxy compound, polyester polyether polyol is mentioned as a typical example. The
polyester polyether polyol has a polyester moiety and a polyether moiety in its molecule.
[0024]
Therefore, the ozone resistance to deterioration of the resulting foam is improved as compared to
the ether foam. In addition, heat and humidity resistance can be made comparable to that of
ether foams. As the polyester polyether polyol, for example, one obtained by ring-opening
polymerization of an aromatic polycarboxylic acid anhydride such as phthalic anhydride and PO
with polyoxypropylene triol formed by adding PO to glycerin is used. be able to. The use of this
polyester polyether polyol also improves the strength, elongation, in particular the elongation
after compression molding, of the foam obtained.
[0025]
The quantitative ratio of the high molecular weight polyether polyol to the polymer polyol
component is not particularly limited. However, in order to improve cold resistance and strength,
elongation, hardness, etc. of the speaker edge in a well-balanced manner, the weight ratio of the
high molecular weight polyether polyol to the polymer polyol component is set to about 1/1 to
2/1. Is preferred. In the present invention, as the polyol, one usually used for producing a flexible
foam can be used in combination. For example, polyester polyol, a general-purpose polyether
polyol having a molecular weight of less than 3500, particularly 3,000 or less, is used in an
amount ratio of about 40 wt% or less, particularly about 30 wt% or less, when the total amount of
polyol is 100 wt%. be able to.
[0026]
When a specific hydroxy compound is used, as in the fifth invention, when the total amount of
the polyol contained in the polyol component is 100 parts by weight, the high molecular weight
polyether polyol is “20 to 60 parts by weight The polymer polyol component is preferably "10
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to 50 parts by weight", and the specific hydroxy compound is preferably "10 to 35 parts by
weight". As for these quantitative ratios, it is more preferable to use 25 to 45 parts by weight of a
high molecular weight polyether polyol, 25 to 45 parts by weight of a polymer polyol
component, and 20 to 35 parts by weight of a specific hydroxy compound. When these polyols
are used at the above-mentioned quantitative ratio, cold resistance, strength, elongation and the
like are sufficiently improved, and ozone resistance, moisture heat resistance and the like are also
improved.
[0027]
The 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. In addition, fluorocarbon compounds or other halogenated
hydrocarbons can also be used as necessary. As a catalyst, metal salts of carboxylic acids such as
sodium acetate, lead octylate, zinc octylate, cobalt naphthenate and stannas octoate can be used.
[0028]
As the catalyst, alkoxides or phenoxides of alkali metals or alkaline earth metals such as sodium
methoxide and sodium phenoxide can also be used. In addition, amine catalysts such as
triethylenediamine and its formate, dimethylethanolamine, tetramethylhexamethylenediamine, Nmethylmorpholine, N-ethylmorpholine, dimethylaminomethylphenol and pyridine can also be
used. As the 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.
[0029]
Further, as described above, when the specific hydroxy compound is used in combination, the
ozone resistance to deterioration of the foam and the heat and humidity resistance are improved.
However, this particular hydroxy compound alone may not be particularly resistant to ozone
degradation, in which case the composition may also be formulated with a specific amount of an
aromatic secondary amine compound. As a result, it is possible to obtain a polyurethane foam
speaker edge having both of the ozone resistance against ozone degradation and the heat and
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humidity resistance.
[0030]
The aromatic secondary amine compounds include phenyl-1-naphthylamine, alkylated
diphenylamine, N, N′-diphenyl-p-phenylenediamine, p- (p-toluenesulfonylamide) diphenylamine,
and 4,4′- Examples include (α, α-dimethylbenzyl) diphenylamine, mixed diallyl-pphenylenediamine, octylated diphenylamine and the like. In addition, amine-ketone compounds
such as poly (2,2,4-trimethyl-1,2-dihydroquinoline) and 6-ethoxy-1,2-dihydro-2,2,4trimethylquinoline are used. It can also be done.
[0031]
These aromatic secondary amine compounds can be blended in a large amount such as 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. When this is converted to 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. The aromatic secondary amine compound 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 may
not be 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 aromatic secondary amine compound is particularly preferably in the range of 1 to
10 parts by weight. With this compounding amount, a polyurethane foam speaker edge with
excellent ozone resistance can be obtained, and at the same time, reaction and curing of foam
formation are easy, and there is no problem in operation.
[0032]
In addition, the combination of this aromatic secondary amine compound improves not only the
resistance to ozone deterioration but also the improvement of the weather resistance, but in
order to further improve the weather resistance, it is necessary to add an ultraviolet absorber. Is
preferred. 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,
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particularly about 0.5 to 1.5% by weight, based on 100% by weight of the polyol. The aromatic
secondary amine compound and the ultraviolet light absorber may be previously added to the
polyol component or the polyisocyanate, or may be added simultaneously when mixing the
polyol component and the polyisocyanate. .
[0033]
Moreover, when the speaker edge made of polyurethane foam is installed in the door trim of a
car, moisture, such as rain water, which enters inside becomes a problem. In the speaker edge
used for such an on-vehicle speaker, excellent waterproofness is required, and it is necessary to
use a foam having low water absorption and low air permeability. When the water absorption of
the foam is high, the waterproofness is insufficient and, in particular, it can not be used as an
edge material of a speaker disposed inside a door trim of a car. 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.
[0034]
In order to obtain a speaker edge excellent in waterproofness, it has a hydrocarbon group having
6 or more carbon atoms or a group containing a hetero atom at one end or in the middle, and
reacts with the isocyanate group contained in the polyisocyanate at the other end. Active group
or one active group which reacts with active hydrogen groups contained in the polyol in the
above-mentioned polyol component (these active groups are carbon atoms at the end of the
molecular chain or carbons next to the carbon atom at the end) Bonded to an atom. Foams
obtained by reacting compositions containing terminal monofunctional compounds having) can
be used.
[0035]
The hydrocarbon group or hetero atom-containing group of the terminal monofunctional
compound may be a linear group or a branched group, and may be a saturated group or an
unsaturated group. Furthermore, the hydrocarbon group may contain an aromatic group, an
alicyclic group or these groups in addition to the aliphatic group. The terminal monofunctional
compound may have one of these various hydrocarbon groups or a group containing a hetero
atom, or may be a mixture of two or more hydrocarbon groups and the like. The number of
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carbon atoms or hetero atoms such as hydrocarbon groups is preferably 6 to 48, and more
preferably 8 to 36, and these are appropriately used in consideration of the required
waterproofness, ease of handling, and the like. Furthermore, as the terminal monofunctional
compound, one type of a compound having one active group that reacts with an isocyanate
group or an active hydrogen group may be used, or various types may be used in combination .
[0036]
Here, the terminal monofunctional compound means that the active group is bonded to only one
of the plurality of molecular terminals of the compound having a plurality of molecular terminals.
In addition, as a group containing a hetero atom, for example, -NH-, -O-, -S-, -CO- and -N (R)-(R is
an alkyl group. And the like. The carbon number of at least one of hydrocarbon groups bonded to
both sides of these active groups may be 6 or more.
[0037]
As the terminal monofunctional compound, octadecyl isocyanate, monoisocyanate derived from a
mixture of hexadecylamine and octadecylamine, and the like can be used. In addition, 1-octanol,
1-decanol, lauryl alcohol, oleyl alcohol, others, branched higher alcohols, and monoalcohols
having -O-, -S- or the like on the terminal side (eg, ROCH2-CH2-OH etc.), etc. It 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.
[0038]
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 required to be waterproof, taking into
consideration the carbon number of hydrocarbon groups and the like of the terminal
monofunctional compound to be added, and the kind of functional group, the reactivity with the
main component polyisocyanate and polyol, etc. Determined by When the amount is less than 0.1
parts by weight, sufficient waterproofness can not be obtained. On the other hand, if the amount
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is more than 35 parts by weight, it is not preferable because molding of the foam itself becomes
difficult or the properties inherent to the foam such as physical properties of the resulting foam
are impaired.
[0039]
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.
[0040]
BEST MODE FOR CARRYING OUT THE INVENTION A flexible slab foam was produced according
to a conventional method using a polyol component containing a polyol shown in Table 1
(Comparative Example) and Table 2 (Example). The details of each component are as follows.
[0041]
(1) Polyol trade name "GP3000" (manufactured by Sanyo Chemical Industries, Ltd.): Glycerinbased propylene oxide adduct, average functional group number; 3, average molecular weight;
3000, hydroxyl value (OHV); 56 trade name "N2200" (Nippon Polyurethane Co., Ltd. Made from:
polyester polyol obtained by condensing diethylene glycol and trimethylolpropane with adipic
acid, OHV;60
[0042]
Prototype “# 3500”: glycerin-based propylene oxide adduct, average functional group number;
3, average molecular weight; 3500, OHV; 48 trade name “GP4000” (manufactured by Sanyo
Chemical Industries, Ltd.): glycerin-based propylene oxide adduct, Average functional group
number; 3, average molecular weight; 4000, OHV; 42 trade name "35-34" (made by Takeda
Pharmaceutical Co., Ltd.): Glycerin-based propylene oxide adduct, average functional group
number: 3, average molecular weight: 5000, OHV ;34
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[0043]
Trade name "CP3943" (Mitsubishi Kasei Dow Co., Ltd.): 70% by weight of styrene component and
30% by weight of acrylonitrile, polymer polyol, solid content: 42% by weight, OHV; 28 "polyester
polyether polyol": PO with glycerin Those obtained by ring opening polymerization of phthalic
anhydride and PO with polyoxypropylenetriol having an average molecular weight of 1,500
added and having an average molecular weight of 3000, OHV;56
[0044]
In addition, as a polyisocyanate, a catalyst, and a foam stabilizer, the following thing was used by
the following amount ratio of all the Examples and comparative examples.
The compounding amount of each component is “parts by weight” when the total amount of
polyols is 100 parts by weight excluding polyisocyanate.
(2) Polyisocyanate: Nippon Polyurethane Co., Ltd., trade name "TDI 80" (TDI, isocyanate index;
110) (3) Catalyst: Nippon Emulsifier Co., Ltd., trade name "LV 33" (amine based catalyst, 0.3
parts by weight), And Johoku Chemical Co., Ltd., Stanas Octoate (metal catalyst, 0.3 parts by
weight) (4) Foam control agent: Nippon Unicar Co., Ltd., trade name "L520" (block copolymerization of dimethylpolysiloxane and polyether Polymer, 1.2 parts by weight)
[0045]
Physical properties, acoustic performance and the like were evaluated by the following method
using the obtained soft slab foam, or a speaker edge made of this foam and a speaker using this
speaker edge.
It calculated | required from the peak temperature of loss elastic modulus G '' of a viscoelastic
spectrum. Measuring device; Dynamic viscoelasticity measuring device, manufactured by
Rheometrics, model "RDA-700"
[0046]
b) Cold acoustic resistance test A voice coil having a voice coil diameter of 26.2 mm, a cone outer
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diameter of 106 mm, and a weight of 3.3 g, made of polypropylene paper, was joined to the
speaker edge molded using the foam of Example and Comparative Example, and the same voice
coil Assemble the same magnetic circuit speaker (Matsushita Electronics Co., Ltd., product
number "14PL05A"), add rated input of 15 W white noise under low temperature of -20 ° C and
-30 ° C, and continuously for 48 hours The operation test was conducted.
[0047]
c) Sound pressure frequency characteristics and harmonic distortion characteristics The cone
paper produced under the same conditions as in the above b) was joined to the speaker edge, and
this was assembled to the above b) speaker and measured according to JIS C 5531.
In addition, these tests were implemented about comparative example 1, 2 and each Example. d)
Durability Acoustic Test Using the same speaker as in b) above, a music source was input at a
peak input of 50 W, at an average level of 25 W, and a continuous operation test for 96 hours at
normal temperature was conducted. This test was also performed for Comparative Examples 1
and 2 and each Example.
[0048]
e) Thermoforming (thermoforming time) Sheets of 7 mm thickness of each of the soft slab foams
of Examples and Comparative Examples were hot-pressed into the following roll edge shape. Roll
diameter: 4 mm, roll inner diameter: 107 mm, roll outer diameter: 125 mm, total roll height: 6.4
mm, molding thickness: 0.6 mm Note that the heat press condition is a mold temperature of 210
± 5 ° C., total pressure of 1 ton And The thermoforming property was evaluated by the molding
time required to reliably form a predetermined shape.
[0049]
f) Hydrolysis In the same manner as in the above b), the speaker edge to which cone paper was
bonded was immersed in a 1 N aqueous solution of sodium hydroxide, and changes in shape etc.
were visually observed. g) Form hardness conforms to ILD JIS K 6401. When a load of 4.9 N is
applied to a sample of 300 × 300 × 50 (thickness) mm, the original thickness is 75% against
the original thickness at a compression speed of 400 mm / min using a disc with a diameter of
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15
200 mm. The hardness after 20 seconds from immediately after compression by 25% was
measured.
[0050]
h) Lowest resonance frequency (F0) A cone paper prepared under the same conditions as above
was joined to a speaker edge and this was measured as a test piece. In Comparative Example 1,
since F0 was too small, in order to obtain F0 equivalent to Comparative Example 2 and each
example, it was necessary to increase the thickness of the test piece to 8 mm. The results are
shown in Table 1 and Table 2.
[0051]
According to the results of Tables 1 and 2, although the foam of Comparative Example 1 has no
problem in thermoforming, etc., it has a high Tg, and a cold acoustic test and a durable acoustic
test at -30.degree. It can also be seen that there is a problem of tearing of the edge. In addition,
the lowest resonance frequency is also low, and in order to be equal to that of the embodiment,
the thickness needs to be 8 mm. In the ester foam of Comparative Example 2, although the edge
fracture is somewhat improved, the harmonic distortion is large and the thermoforming property
is also reduced. Furthermore, the hydrolyzability was very poor, and it almost decomposed and
did not retain the shape of the edge. Further, in the ether-based foam of Comparative Example 3,
the Tg is low and there is no problem with cold acoustic characteristics, but the hardness is
lowered, the thermoformability, the lowest resonance frequency and the like are considerably
inferior, and the reproducible range is very narrow. It turns out that it becomes. On the other
hand, in the foam of each example, Tg is -35 ° C. or less, and the cold acoustic characteristics
and the like are excellent in cold resistance, and there are no particular problems in other
characteristics such as the thermoforming property. It can be seen that it is a polyurethane foam
or speaker edge of excellent performance.
[0052]
With respect to the foams of Comparative Example 1 and Example 5, the temperature
dependency of 25% CLD hardness, tensile strength and elongation at -40 to 20 ° C was
evaluated. The results are shown in Table 3. Moreover, about 25% CLD hardness, the
measurement result in 60 degreeC and 140 degreeC was also added, and temperature
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dependence was evaluated. The results are shown in Table 4. The measuring methods of this
25% CLD hardness, tensile strength, and elongation are as follows. i) 25% CLD hardness It
conforms to JIS K 6401. When a load of 4.9 N is applied to a sample of 50 × 50 × 15
(thickness) mm, this is the original thickness, which is compressed by 25% at a compression
speed of 50 mm / min by a disc with a diameter of 100 mm. The hardness was measured. j)
Tensile strength, elongation According to JIS K 6301.
[0053]
According to the results in Tables 3 and 4, the temperature dependency of tensile strength and
elongation is not so much different between the foams of Comparative Example 1 and Example 5.
However, it can be seen that the 25% CLD hardness of the foam of Example 5 is relatively low
and is relatively flexible at low temperatures, especially at low temperatures of -40 ° C. Further,
it can be seen that there is no difference in the temperature dependence of the hardness of the
foams of Comparative Example 1 and Example 5 at high temperatures, and the foam of Example
5 does not lose its hardness particularly at high temperatures.
[0054]
In addition, FIG. 1 is the result of having measured the sound pressure frequency characteristic
and the harmonic distortion characteristic using the speaker edge obtained using the foam | form
of Example 5, the comparative example 2, and the comparative example 1. FIG. The measurement
frequency is 20 to 20000 Hz, but here a frequency range of 500 to 2000 Hz is illustrated.
According to FIG. 1, in Comparative Example 2, a large peak dip occurs in the so-called edge
resonance region of 1000 to 1500 Hz, and the peak dip difference of the edge resonance is 8.7
dB. On the other hand, in Example 5, the characteristics are almost flat, and it can be seen that
the peak-dip difference is as small as 2.7 dB. Also in Comparative Example 1, although the
characteristics are substantially flat, a peak dip occurs, and the sound pressure in this band is
lowered by 4.2 dB. Furthermore, the harmonic distortion in the edge resonance region of 700 to
1500 Hz is also large in Comparative Example 2 and small in Example 5 and Comparative
Example 1. As described above, it is understood that the fifth embodiment is low in distortion and
excellent in the sound quality and sound pressure of the midrange that is deeply involved in
human voice reproduction.
[0055]
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According to the first aspect of the present invention, the combination of a high molecular weight
polyether polyol and a specific polymer polyol as a polyol improves cold resistance, acoustic
characteristics, strength, elongation and the like of the obtained speaker edge. Do. Further, by
using the specific hydroxy compound of the fourth invention in combination, it is possible to
improve the resistance to ozone deterioration and the resistance to moist heat aging of the
speaker edge.
[0056]
Brief description of the drawings
[0057]
1 is a graph showing the results of measuring the sound pressure frequency characteristics and
the harmonic distortion characteristics of the speaker edge comprising the foams of Comparative
Example 2 and Comparative Example 1 and Example 5.
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