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JPS6346900

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DESCRIPTION JPS6346900
[0001]
The present invention relates to a diaphragm for a speaker. <Problems to be Solved by the Prior
Art and the Invention> Generally, the material of the speaker diaphragm is made lighter in order
to improve the reproduction sound pressure level, that is, the density (ρ) is low. In order to
lower the reproduced sound pressure frequency, the higher specific elasticity y $ [present]) and
the high sound speed (undershoot 7A), and low distortion and resistance to input In order to
achieve the improvement of (1), higher rigidity (high bending rigidity) is required. Further, in
practical use, it is also required to have physical properties VC-) such as heat resistance and
water resistance. At present, it is considered that a foam made of a thermoplastic resin containing
a large amount of air layer has physical properties such as light weight, high rigidity, and high
specific elastic modulus, and is used as a speaker diaphragm. This foam contains a large amount
of air layer by adding a foaming agent to the thermoplastic resin and thermally foaming from the
viewpoint of the production process to make it contain a large amount of air layer, such as
optical polyethylene foam, pyripropylene foam, polystyrene foam, etc. The gas can be roughly
classified into urethane foam and the like containing a large amount of air layer using a gas
generated upon reaction. However, in the case of the former foam using the second foaming
agent described above, it is necessary to obtain a foam whose foaming temperature is preferably
several tens of degrees higher than the melting point of the thermoplastic resin. Since there is
almost no high temperature blowing agent (at most 180 ° C), the heat resistance temperature of
the obtained foam is determined by the melting point of the thermoplastic resin used, and it is
about 9 ° C or 140 ° C and is heat resistant. Can not obtain a large foam, so the heat resistance
of the speaker diaphragm? There was a limit to raise ['cVi selfishly. On the other hand, in the
case of the latter foam using the two-component reaction gas, uniform foaming is difficult if it is
made thin, and the sheet thickness required for the speaker diaphragm is 0.5 m or less. It can not
be applied to the diaphragm for use. Also, a proposal has been made in which air bubbles are
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mechanically inserted into a thermoplastic resin having a melting point of 150 ° C. or more, and
the air bubble filled thermoplastic resin is molded to obtain a diaphragm for a speaker (JP-A-5869197). Gazette). However, these conventional resin foams have insufficient rigidity. In general,
the diaphragm of the speaker has the same phase over the entire frequency band to be used, that
is, it is ideal that the piston vibrates, and if the diaphragm is deformed or split vibration occurs
during vibration, the sound pressure frequency characteristic or distortion Rate, phase
characteristics, etc. are degraded, which hinders high fidelity reproduction.
In order to solve these problems, flat diaphragms using a honeycomb zan P-inch structure or the
like have recently been adopted. However, a plane diaphragm i-! With a honeycomb structure is
used. Because the construction is complicated, manufacturing error that requires several tens of
processes and multi-eight member members are required f: How expensive is it ?, cheaper than
conventional corn paper etc.) C It was difficult. Oh! ? : There is a problem in that it is difficult to
quantify the yield of the diaphragm because the material thickness of the constituent material is
limited in manufacturing, and the efficiency of the fly-car is low. Also, Arami 4) and carbon fibers,
which are suitable as highly rigid materials to be bonded to the flat surface of honeycomb
materials, are suitable as a cloth, so that their mechanical properties are perfectly isotropic 360
degrees in the plane, and they are good. However, there is a dissatisfaction that even if the
isotropy can be reduced by making the synthetic paper or the non-woven fabric by means of
making the fibers into short fibers and making them into paper, the rigidity becomes insufficient.
In order to solve the above-mentioned problems, the present invention comprises the following
constitution. The present invention! -1: A foam of an aromatic polymer which forms a liquid
crystal phase in a molten state] on both sides of the layer consisting of an aromatic polymer, the
initial modulus of the surface Q in any direction is slightly expressed as 600 to. H) 4 ') Non-lough
Enylene Tele 7 (hereinafter referred to as PPT people) One or two or more films adhered from a
polymer are adhered to form a structure. Speaker diaphragm. The aromatic polymers that form
liquid crystals in the molten state, that is, thermotropic liquid crystal polymers, used in the
present invention are polymers that are liquid crystalline (ie, anisotropic) in the melt phase. The
polymers of this class have been described in various terms, including 'liquid crystalline', 'liquid
crystalline' and 'anisotropic'. As stated in the tube section, the polymer of this strain is considered
to take a regular one-hundred line array of molecular chains. The molecules are arranged in this
manner to be in the * state, and the liquid crystal state is called the nematic phase of the liquid
crystal substance. このよう′! j: The polymer 1 is generally elongated and flat, with a high
degree of cleavage along the long axis of the molecule, usually either normal or not. 11) It is 11
from a monomer having 7 or more chain extension-length bonds. Such polymers do not readily
form liquid crystals in the melt phase and thus S (ie, exhibit anisotropy). Such properties can be
confirmed by conventional polarization inspection using orthogonal polarizers. More specifically,
confirmation of the anisotropic melting phase can be carried out by using a polarizing
microscope and observing the sample placed on the hot stage under a nitrogen atmosphere at a
magnification of 40 times.
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The polymers of the present invention are optically anisotropic. That is, light is transmitted when
inspected between orthogonal polarizers. If the sample is optically anisotropic, it transmits
polarized light, even in the quiescent state. As such a thermotropic liquid crystal tracker,
polyethylene terephthalate is melt-exchanged 12 with p-hydroxybenzoic acid @ for
transesterification reaction: obtained by a method, Tff, a method of copolymerizing both, Z)
copolymer weight The combination is famous, and it has been announced by Kodak under the
development name of X-7G. In addition, many copolymerization compositions (-) aromatic
polyesters mainly composed of p-hy-l 'Elf Gicibenzoic acid and 2-pyroxy naphthaline-G-cari 7
acid, and ami P 5 aromatic aromatics + y which introduced the bond, Nistel proposed it, and
recently, a few compositions have been marketed. That is, Dartco, Inc. under the trademark Xyd
Red, and Celanese, under the trademark ectra, announced it. As another thermotropic liquid
crystal, JP-A-51-138800 and other aromatic polyazomethines are used, and the jAK of the
present invention is used. Aromatic polymers suitable for use in the present invention tend to be
substantially insoluble in common solvents 17, and are unsuitable for solution processing.
Alternatively, these polymers can be processed into articles by conventional melt processing
methods. Fully aromatic suitable for use in the present invention? The polyester generally has a
weight average molecular weight of about 2,000 to 200,000, preferably about i, ooo to 50,000,
particularly preferably about 20.000 to 25,000 "c. The foam layer of the thermotropic liquid
crystal polymer of the present invention can be formed by any suitable conventional method
such as extrusion, injection molding and the like. For example, pellets of the thermotropic liquid
crystal polymer are mixed with a powdered foaming agent7, and this mixture is extruded at a
temperature higher than the melting temperature of the polymer used and extruded from a
suitable orifice (eg, slit die). The body can be formed 7 by screw extrusion. The blowing agent
decomposes at the extrusion temperature and a gas such as nitrogen or carbon dioxide is evolved
inside the extruded polymer melt, thereby forming a foam. The extruded foamed polymer is
quenched and cooled by a suitable means like a forced air flow. The type of extrusion device used
is not particularly limited, and any suitable surface device can be used. The temperature and
pressure conditions under which the liquid crystal polymer can be extruded are not particularly
limited in the method of the present invention, and those skilled in the art can easily determine
these conditions.
Generally, extrusion of the thermotropic liquid crystal polymer foam is at a temperature in the
range of about 250-390 ° C. (depending on the melting temperature of the polymer) and a
pressure in the range of about 7.0-350 / cyn " You can go below. The thermotropic liquid crystal
polymers of the present invention generally have a density of about 0.1 to 0.7517 cm "after
foaming. Preferably, the density of such foamed polymers is in the range of about 0.3 to 0.75 f /
cm. Also, the melting point of the foamed thermotropic liquid crystal polymer of the present
invention will fall within the range of about 250-370 ° C. depending on the ± 2 trimer used.
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The method of producing the foam layer which forms the diaphragm for a speaker according to
the present invention includes the method of first extruding the foam 2 in a foot shape, and then
shaping the reed into a predetermined shape, There is a method of injection molding directly into
the mold of the diaphragm for a speaker, and any one of them can be selected from the diameter
of the intended speaker, performance, the number of production, and the like. Conventional high
temperature blowing agents can be used to produce the foam IJ-r of the present invention. For
example, suitable blowing agents include those marketed under the following trade names
(although limited to the following): Expandax 5PT (which is derived from 5-phenyl tothrazole;
sold S tepan Ohemie Resistant Co,), Ftcel THT () consisting of Ririch Ria, Khun; selling pinofls
engineering ndustrjalOhemlcals), Oetogen HT550 (h '?? Consists of Ladine derivatives: Sold
Uniroyal Ohmical) and Kemtec 500 (Sherwln-Williams Chemicals). Such force blowing agents
decompose at temperatures within the range of about 240-310 ° C. The decomposition of the
blowing agent depends on temperature as well as time. It is important to match the
decomposition temperature with the processing temperature of the 19 lmer. If the blowing agent
decomposes before the lymer dissolves sufficiently, the cell structure may be poor and an
unsatisfactory surface appearance may be obtained. The need for a blowing agent will generally
be in the range of about 0.1% to a few percent by weight y, depending on the gassing rate of the
blowing agent and the desired rate of density loss. Preferably, the amount of blowing agent used
will be in the range of about 0.2 to 0.5% by weight. Also a chemical blowing agent? Properly
selected 7, temperature and / or 7+, I ′ ′ ii pressure (with more foaming can be controlled.
Temperature control of the foaming action is more reliable than pressure control, and the use of
the chemical blowing agent is preferred.
It is also possible to blow a suitable amount of gas into the molten polymer to form a foamed
polymer. But by the way it takes! 7 It is difficult to secure sufficient gas dispersion. Various fillers
and reinforcements may be used to enhance the various properties of the foamed polymer. For
example, the foam can be reinforced using suitable reinforcements such as glass fibers, carbon
fibers, Arami Fl fibers, and the like. Such reinforcements may generally be used in amounts of up
to about 50% by weight, preferably about 10 to 50% by weight, based on the weight of the foam.
Fillers such as pigments, antioxidants and nucleating agents may be added. The typical amount of
filler required is in the range of about 0.2 to 10% by weight, preferably about O, S to 2% by
weight. However, the foam of the thermotropic liquid crystal polymer of the present invention is
self-reinforcing and has mechanical properties comparable to fiber reinforced polymer materials.
The orientation of the polymer molecules around the closed cell Δ pull is caused by the field of
the biaxially extensible flow of the 膨 張 expanding non-roll during the foaming process. The rodlike molecules of the liquid crystal polymer can be easily oriented by the flow field, and the
obtained biaxial orientation can be maintained. After being shaped, it is also preferable to apply a
heat treatment, and in the preferred embodiment, along with removing anisotropy of molecular
orientation at the time of molding, the effect of increasing molecular weight is known in these
thermotropic liquid crystal polymers. Can be expected to have an effect of increasing strength,
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improving crystallinity, and melting point, that is, improving heat resistance. The heat treatment
of the foam can be carried out in an inert atmosphere (e.g. nitrogen, carbon dioxide, albine,
helium) or a flowing oxygen-containing atmosphere (e.g. air). The use of a non-oxidizing
atmosphere is preferred to avoid the possibility of thermal degradation. For example, the foam
may be heated to a temperature about 10-30 ° C. lower than the melting temperature of the
foamed liquid crystal polymer, at which temperature the foam remains a solid substance. The
heat treatment temperature is preferably as high as possible without exceeding the melting
temperature of the polymer. As the melting temperature of the polymer rises during the heat
treatment, it is particularly preferred that the heat treatment temperature 1 be gradually
increased accordingly. The heat treatment time is generally in the range of several minutes to
several days (or more), for example, 0.5 to 200 hours or more. Preferably the heat treatment is
conducted for 1 to 48 hours, typically about 5 to 30 hours. Generally, the heat treatment time
varies depending on the heat treatment temperature, and the higher the heat treatment
temperature used, the shorter the treatment time.
Thus, a polymer with a high melting point can be reduced in time for one heat treatment because
higher heat treatment temperatures can be applied without melting the polymer. Another
configuration of the imaging plate for a speaker according to the present invention is a
composite structure in which one or two or more films composed of PPTA-based polymer are
laminated on both sides with the above-mentioned foam layer sandwiched, And, the film is
characterized in that it has an initial modulus of at least 6001 g / ran "in any direction in the
plane direction. Here, a PPTA-based polymer refers to a polymer in which the repeating unit of
PPTA is 90 mol% or more, and is substituted by a substituent such as 50 mol X or less X of a
paraphenylene ring, halogen, etc. It may be The degree of polymerization of the polymer is
preferably as high as 3.5 or more, more preferably 4.5 or more, since the degree of
polymerization of the polymer is as low as possible because a film with good mechanical
properties can not be obtained. .2 is selected to give a degree of polymerization which gives a
value of 9) measured at 30.degree. C. by dissolving f. The PPT human-based film of the present
invention, when used alone, has two or more layers of the film laminated and used as a laminated
film group in any direction in the plane direction. However, having an initial modulus of at least
600 k / ran 2 is necessary as a good speaker diaphragm, and more preferably 700 Kf / m or
more. More preferably, the sum of the initial modulus in the direction orthogonal to the direction
showing the lowest initial modulus is i + s o o h /-or more. Thus, films exhibiting high initial
modulus in either direction can not be obtained with conventional materials, but are first
obtained with PPT-based polymers, preferably films of PPTA. In addition, these films show a
large value of about 15 h / rat "in the tensile strength in any direction in the plane direction, and
they are easy to be machined for compounding, and even if they are used in actual use. It is also
an advantage that it is very durable. It is preferable that the PPT human-based film used in the
present invention has a plane orientation defined by a crystal orientation angle by X-ray
diffraction described below. The incidence of the X 'ray is divided into a case of incidence at right
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angles to the film surface (hereinafter referred to as Tv force direction) and a case of incidence in
parallel to the surface (hereinafter referred to as Sv direction). The film used in the present
invention has a thick table diffraction peak at 2θ # 23 ° by X-rays in the direction of TV force,
and the crystal orientation angle at this 20 # 23 ° is preferably 30 ′ or more, and more
preferably More preferably, it is 50 'or more.
Furthermore, a large diffraction peak of 2θ gradient 18 ° appears on the equatorial line by the
incidence from the KSV direction, but it is preferable that the crystal orientation angle in this 20
# 18 ° is 60 ° or less. Although the film of the present invention has a structure of so-called
plane orientation when both of these crystal orientation angles are satisfied, the diffraction
pattern of TV is almost completely 360 ° equal plane orientation as a De Noi ring. It exhibits a
high degree of initial modulus due to its orientation and orientation in any of the plane
directions. A publicly known method can be adopted as a measuring method of the crystal
orientation angle, and for example, it is carried out by the following method. Place the counter at
a predetermined 20 angles and rotate the film 180 ° to obtain a diffraction intensity curve. In
the TV, around the highest intensity, it is rotated between 90 ° back and forth. The arc length in
the diffractogram, which corresponds to a point showing half the intensity relative to the
baseline drawn between the lowest intensity points of this white line, in degrees (ie 50% of the
highest intensity baseline Measure the angle) with respect to the point, and let it be the crystal
orientation angle of the sample. At the time of measurement, the film can be measured as small
as it is necessary to measure the diffraction intensity. Next, a method for obtaining this more
PPTA film will be described. That is, pp'r person's optical anisotropy r-p is prepared using a
solvent such as sulfuric acid, and if necessary degassing and filtration are carried out, after which
it is discharged from a die and flowed onto a flat body. Stretch, then apply moisture and
optionally apply heat to make cast P-p fraction isostatic, solidify the r-p, wash and dry while
limiting shrinkage. Stones can be manufactured by doing. And optionally, for example, when a
film having high strength and high Young's modulus in one direction is desired, it can be
achieved by uniaxially stretching the wet film after washing, and has high strength and high
Young's modulus in all directions. If a film is desired, it can be achieved, for example, by biaxially
stretching the wet film, and if a film with good dimensional stability is desired, it can also be
heat-treated, for example, after drying. When these PPTA films are laminated, they are attached
to the foam layer, and in advance, in order to increase the adhesive strength, plasma treatment,
electron beam treatment, sulfonylaceh P compound, or alkoxy compound etc. are reacted. That
pre-processing is performed may be preferably performed as long as it does not impair the
above-mentioned patent configuration requirements. Similarly, with regard to the foam layer, it is
preferable that a treatment for enhancing adhesion be applied.
The adhesive used to bond the film is not particularly limited, and is usually an epoxy resin, a
phenol resin, an unsaturated polyethyl resin, a melamine resin, a diallyl phthalate resin, a
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maleimide r-based resin, which is generally used. Etc. are used. The film and the foam layer
should be bonded with these resins and at the same time be heated / cured if necessary, and be
shaped like a flat plate, in some cases a cone, or a necessary rim structure. May be done.
Operation of the Invention In the present invention, a film made of pprA-based polymer, which is
a new material having a high degree of isotropy in all directions in a special plane, is wound in a
sun-p-wich shape. In addition to being light weight suitable as a speaker material, it provides
high specific rigidity and is isotropic in all directions in a plane. Therefore, undesirable
phenomena such as divided vibration are less likely to occur. Also, the foam layer itself is
characterized by the high degree of crystallinity due to the rigidity of the molecular chain, and
the molecule which is easily high due to the shear force and the elongation force due to the flow,
as a feature of the aromatic primer which forms a liquid crystal phase in the molten state. By
orienting and giving molded articles of high strength and high modulus, the foam cell walls are
highly oriented by foaming the primer so that the preferred specific weight as a speaker
diaphragm and simultaneously high specific modulus, naturally high degree It exhibits isotropy
and promotes the features of the invention described above. Next, the present invention will be
described by way of examples. (Reference example) Production of PPTA film A PPT human
polymer with lnlnh of 5.5 was melted in 99.7% sulfuric acid at a polymer concentration of 11.5%,
and a dope with optical anisotropy was obtained at 60 ° C. . After degassing under vacuum,
carefully pass through the tank flutter filter, keep the 1.5 m curved tube at about 70 ° C to
reach the die through the gear pump, and have a 0.15 m x 300 m slit. Polished tantalum bell)
(777! Cast at about 90 ° C with relative humidity of 85% and cast r-p? It was optically isotropic
and was introduced into water at 5 ° C. and solidified with the belt. The coagulated film was
then peeled from the belt and run in warm water at about 40 ° C. for cleaning. The film after
cleaning is not dried but is stretched 1.1 times in the film forming direction with a roll, and then
the film forming direction is stretched at a constant length of 1.2 times in the film forming
direction using a tenter at 240 ° C. Hot air dried. Is the film obtained 15 μm thick? Do you
have an X-ray diffraction pattern in the TV direction?
Indicated, orientation angle is 55 °! The +, SV force direction indicates an orientation angle of
38 °, and it can be said that it exhibits a rough surface orientation. The initial modulus of the
film is 1 + 340! l-y / m 2, width direction 7% 1,410 Kf / wn, “t”, regardless of the direction of
the film, be sure to enter between these figures. Also, for reference, the strength is 9 / rm "in the
film forming direction 32 and 2 / Wr in the width direction 34. n2, Elongation is 20% and 15%
respectively. Example 1 Logarith viscosity (25 g% of 2-hydroxy-2-naphthoyl units and 75 mol%
of p-oxybenzoyl units), when dissolved in pentafluorophenol at 60 ° C. in a concentration of 0.1
wt-J1% ( η Inh) t /: /) to 8.5 thermotropic liquid crystal polymer (2) mixed with 0.5 wt 2
powdered Kemtec 500 blowing agent and 1.0 wt% talc (nucleating agent) . The mixture was
extruded at 307 ° C. to produce a sheet. A static mixer was used just prior to extruding the
mixture from the die to ensure uniform mixing of the blowing agent and the melt. The PPTA film
shown in the comparative example was adhered to both sides of the obtained foam sheet with an
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epoxy resin, and was formed into a flat plate shape by a hot press while being heat cured to
produce a diaphragm. This diaphragm has a density C1, 59S '/-and a specific elastic modulus of
4, 3 x 10 <1> Odyne / (1'), a speed of sound (V1), 2, 70 x 105 cm / sec. To soak in, conventional
corn paper is dense! 0.4 to 0.8, specific elastic modulus 0, 8 to 2, 5 × 10 10 dynes 7 cm 2,
sound velocity 0.5 to 1 × 10 5 σ // C. (Effects of the Invention) The speaker diaphragm of the
present invention has a high specific elastic modulus in the amount of @ and a conventional
honeycomb core? Since a homogeneous diaphragm can be formed more easily than in the case of
use, a speaker with a desirable sound quality can be manufactured while ensuring stable
performance.
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