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DESCRIPTION JPH05260591

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DESCRIPTION JPH05260591
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
method of manufacturing speaker constituent members such as speaker diaphragms, sub cones,
center caps, etc., which is made mainly of wood pulp, and more particularly to a speaker
construction for achieving flame resistance of these The present invention relates to a method of
manufacturing a member.
[0002]
2. Description of the Related Art Most of the speakers currently in practical use are occupied by
electrodynamic speakers. This is because the electrodynamic loudspeaker can extend the bass
reproduction limit to obtain a large amplitude, and can achieve a considerable efficiency
depending on the design.
[0003]
FIG. 1 shows a cone speaker as an example of an electrodynamic speaker, and a ring-shaped
magnet 3 is fixed to an upper portion of a yoke 2 having a center pole 1. A ring-shaped plate 4 is
fixed to the top of the magnet 3. In a gap formed by the plate 4 and the center pole 1, a coil
bobbin 6 around which a voice coil 5 is wound is disposed.
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[0004]
A vibrating plate (cone) 7 is attached to the coil bobbin 6. Inside the diaphragm 7, a center cap 8
is disposed. The outer peripheral edge of the diaphragm 7 is held via the edge 9 at the opening
edge of the frame 10 attached to the plate 4. In the figure, 11 indicates a ring-shaped packing,
and 12 indicates a damper.
[0005]
By the way, the above-mentioned diaphragm 7 and center cap 8 grade | etc., Which are vibration
parts of a speaker are manufactured with wood pulp in many cases. This is because when the
main component is wood pulp, the vibrating part has a small mass, a relatively large Young's
modulus, and an appropriate internal loss, and can be produced by paper-making. This is because
there is an advantage that it is possible to form even complex shapes.
[0006]
However, since the above-described vibrating parts are mainly made of wood pulp and are
combustibles, they have the disadvantage of being vulnerable to fire. In particular, when an
excessive current flows through the voice coil 5 or when the voice coil 5 is installed at a high
temperature such as near a transformer of a television, there is a risk of ignition.
[0007]
For these reasons, flame retardants such as boric acid, boron, halogenated hydrocarbons, and
phosphoric acid compounds have conventionally been used.
[0008]
However, while boric acid and boron exhibit their effects due to heat absorption and melt
coating, they have a high hygroscopicity and have the disadvantage that the physical properties
of the diaphragm mainly composed of wood pulp are significantly reduced.
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In addition, halogenated hydrocarbons are not so effective for cellulose fibers and need to be
added in large amounts.
[0009]
On the other hand, phosphoric acid compounds are known to be effective for cellulose fibers in a
small amount due to their dewatering and carbonizing action.
[0010]
From such a thing, many phosphoric acid type compounds are used with respect to a wood pulp,
and what was melt | dissolved in water or the organic solvent is provided by impregnation, a
spray, surface coating, etc.
[0011]
However, in the case of providing a water-soluble flame retardant, the product is deformed in the
subsequent drying step, and therefore, there is a problem that the material has to be dried while
being pressed by a mold or the like.
In addition, in the case of applying a flame retardant dissolved in an organic solvent, an
explosion-proof structure is required for the drying device, and a local exhaust device is also
needed to improve the working environment, and special equipment is required. There is.
[0012]
For this reason, it is considered to apply a flame retardant to wood pulp by a method similar to
sizing and dyeing conventionally performed.
However, at present, this method has not been put to practical use because there is no fixing
agent to be fixed efficiently to wood pulp.
[0013]
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The present invention has been made to cope with such a situation, and a speaker component
made incombustible by a simple process and equipment by efficiently applying a flame retardant
to a material mainly composed of wood pulp. An object of the present invention is to provide a
method of manufacturing a speaker component that can be easily obtained.
[0014]
SUMMARY OF THE INVENTION In order to achieve the above object, the method for producing a
speaker component of the present invention comprises suspending fine particles of a flame
retardant in a sodium alginate dope and flash spinning it. The present invention is characterized
in that the inclusive alginic acid fiber obtained by the above method is blended with a raw
material mainly composed of wood pulp and formed into a paper to obtain a speaker component.
[0015]
In the method for producing a speaker component according to the present invention, fine
particles of a flame retardant which is insoluble or poorly soluble in water are suspended in an
aqueous solution of sodium alginate, and this is spun in a coagulation bath to obtain fibers. In
addition, fibrillated fibers are obtained by the flash spinning method.
[0016]
That is, the alginic acid fiber coagulated by the coagulating solution becomes insoluble in water,
and the flame retardant entrapped inside does not fall off.
Further, since it is in the form of fibers, it can be easily mixed with wood pulp, and can be
handled in the same manner as wood pulp. Thus, it is possible to easily obtain a flame retardant
speaker component using conventional processes and equipment.
[0017]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be
described in detail with reference to the drawings.
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FIG. 2 is a view showing the concept of a flash spinning method according to an embodiment of
the method of manufacturing a speaker constituent member of the present invention, and a
pressure tank 20, a coagulation bath 30, and a circulation tank 40 are provided.
[0018]
The pressurizing tank 20 is provided with an injection nozzle 21 whose injection port is directed
into the coagulation bath 30.
[0019]
Inside the coagulating bath 30, a stirring blade 32 attached to a rotating shaft 31 is disposed.
A discharge pipe 33 whose discharge port is directed to the inside of the circulation tank 40 is
provided on the side of the coagulation bath 30.
[0020]
The circulation tank 40 is provided with a filtration tank 41 for filtering the spun fibers
discharged from the discharge port of the discharge pipe 33.
Further, a circulation pump 42 is provided in the circulation tank 40, and the filtrate filtered by
the filtration tank 41 is circulated in the coagulation bath 30 by a circulation pipe 43.
[0021]
The speaker component is manufactured as follows. First, dissolve sodium alginate in water and
prepare a 1% aqueous solution. To this is added, for example, a powder of melamine phosphate
as a flame retardant as a ratio of sodium alginate to 100%, and sufficiently dispersed by stirring.
Next, calcium chloride is dissolved in water as a coagulating solution to prepare a 10% aqueous
solution.
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[0022]
An aqueous solution of sodium alginate in which a flame retardant is dispersed (hereinafter
referred to as a dope) is placed in a pressure tank 20. An air pressure of about 3 to 4 kgf / cm 2
is applied to the pressure tank 20. In addition, although a sodium salt is used as an alkali alginate
in this example, the present invention is not limited to this, and lithium, potassium and ammonia
salts of alginic acid may be used.
[0023]
The dope pressurized in the pressurization tank 20 is vigorously extruded from the injection port
of the injection nozzle 21 into the coagulation bath 30. The coagulation bath 30 is filled with an
aqueous solution of calcium chloride.
[0024]
The dope discharged into the coagulation bath 30 is reacted in an aqueous solution of calcium
chloride in the coagulation bath 15 to obtain fibrillated fibers.
[0025]
Here, fiberization is sufficient if there is a metal ion capable of forming an insoluble salt to
alginate, and calcium ion is used in this embodiment, but not limited thereto, strontium, barium,
aluminum, tin, lead, Other ions such as manganese, chromium, iron, cobalt, nickel, copper, zinc,
silver and the like may be used.
[0026]
Alginic acid is a polysaccharide mainly contained in brown algae.
It has a molecular structure close to that of cellulose fibers mainly composed of β-1,4 bonds of
D-mannuronic acid and L-guluronic acid, and has inter-fiber bonding by hydrogen bonding like
cellulose fibers.
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[0027]
For this reason, when mixed with wooden pulp fibers, the paper strength is exhibited as with the
wooden pulp fibers.
[0028]
The fibrillated fibers are discharged from the discharge port of the discharge pipe 33 into the
filtration tank 41, and the filtration tank 41 separates the fibers and the aqueous solution of
calcium chloride.
The separated aqueous solution of calcium chloride is circulated into the coagulation bath 30 by
the circulation pump 42.
[0029]
The flame retardant-containing calcium alginate fiber obtained through the above steps is
blended with wood pulp fiber.
That is, for example, NUKP (softwood unbleached kraft pulp) is adjusted to a wood freeness of 20
degrees SR as a wood pulp fiber, and 30% of a flame retardant-containing calcium alginate fiber
is blended in this adjusted stock. Then, after forming a sheet with a wire net of a predetermined
shape, it was heated and pressurized to obtain a speaker diaphragm.
[0030]
In the present embodiment, the case where the concentration of the sodium alginate aqueous
solution is 1% is described, but not limited to this example, it may be about 0.5 to 2%, and the
strength and fibrillation of the spun fiber are within this range. The strength of the paper when
mixed with wood pulp can be adjusted by adjusting the degree of. In addition, the flame retardant
to be dispersed is not limited to the above-mentioned melanin phosphate, and if it is uniformly
dispersed in sodium alginate dope and does not affect the spinning, other kind of flame retardant
inclusion fiber It can be applied to flame retardancy of materials other than wood pulp.
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[0031]
Furthermore, in the present embodiment, although the present invention has been described for
the case of manufacturing the speaker diaphragm, the present invention is not limited to this and
may be applied to the case of manufacturing other speaker vibrating members such as a sub
cone and a center cap. In this case, the members can be made flame retardant.
[0032]
As described above, according to the method for producing a speaker component of the present
invention, fine particles of a flame retardant which is insoluble or poorly soluble in water are
suspended in an aqueous solution of sodium alginate, Fibers were obtained by spinning in a
coagulation bath, and fibrillated fibers were obtained by a flash spinning method.
[0033]
Therefore, the alginic acid fiber coagulated by the coagulating solution becomes insoluble in
water, and the flame retardant contained inside does not fall off, and since it is in fiber form,
mixing with wood pulp is easy, and wood Since the same handling as pulp can be performed, it is
possible to easily obtain a speaker component flame-retardant by conventional processes and
equipment.
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