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The present invention relates to an improvement of a loudspeaker diaphragm, in particular to an
improvement of a honeycomb diaphragm. There is a conventional honeycomb diaphragm shown
in FIG. In FIGS. 1A and 1B, (llk '! A surface material with high barrier properties such as FRP
composed of aluminum or reinforcing fiber and thermosetting resin, (2) a core material formed
in a honeycomb structure with aluminum foil, (3rd surface material It is an adhesive that bonds
(1) and the core material (2). The conventional honeycomb diaphragm configured in this manner
has a very low apparent density of the core material, so that a large embedding can be obtained
as the core material, and the conventional material is used because the 111114 property is used
as the surface material. Compared to corn paper. It is praised as a diaphragm '4! The specific
modulus Vp (cnr '/ air 2), which is one of the lIJ's, has the advantage of being about 3 to 4 times
more likely. Therefore, the speaker using this honeycomb diaphragm has a reproduction limit of
the high region about twice that of the speaker using cone paper, and the flexural rigidity of the
diaphragm itself is extremely high due to its large thickness, and the reproduction band is It has
the advantage that the spread and the harmonic distortion can be greatly reduced. However, the
conventional honeycomb diaphragm having such excellent t · f property, which is constituted by
the surface play and the stone side of a light metal such as aluminum, has high internal
resonance because the internal loss of the diaphragm itself is extremely small. However, there is
a disadvantage that the usable reproduction band is limited. Also, if the diaphragm made of FRP
(Fiber Reinforced Plastics) is used as the surface material and the diaphragm made of aluminum
on the stone side also has a large internal loss compared with metal, it is not enough yet, and
thermosetting resin is used as plastic. There is a drawback that it takes time to mold because of
Also, as a countermeasure against the above drawbacks. It is conceivable to use a thermoplastic
resin having a very large internal loss, such as polypropylene, but polypropylene has poor
adhesion and stretchability, making practical use difficult. The present invention has been made
to eliminate the disadvantages of the conventional honeycomb diaphragm as described above,
and is a modified polypropylene obtained by reacting non-specific phase carbon with a surface or
core and a surface material, or the modified polypropylene. Using a honeycomb diaphragm
obtained by combining a mixture of polypropylene and a non-modified polypropylene, having a
large internal loss possessed by conventional polypropylene, and at the same time greatly
improving the adhesion and providing a diaphragm which can be easily formed It is an object.
Hereinafter, an embodiment of the present invention will be described.
Example 1 Polypropylene powder too Ny part with an intrinsic viscosity of 1.5 Add 0.2 parts of
maleic anhydride as unsaturated carboxylic acid as a unsaturated carboxylic acid, add 03 parts of
benzoyl peroxide as a peroxide, After mixing, it is fed to a pot and extruded at 230 ° C. for 7
minutes. Sheets of 0, 2 + m thick were obtained. Denatured under the same conditions-(nonpolypropylene 0.2 dance sheet made for comparison. In order to make a honeycomb diaphragm,
the number and the contact strength (shear strength) of each of the upper sheet and tIIi were
examined. In addition, as an adhesive agent, an adhesive agent with a weight reduction of iiJ 'can
be selected. The above test results? It is shown in Table 1. Table 1 Test results As shown in Table
1, the force of the honeycomb diaphragm. In the constant of the sheet as the surface material
having a large shadow 41 ヲ on η, the embodiment of the present invention has a value similar
to that of the comparative example. The center strength JC corresponding to the contact layer
strength, and the above-mentioned central 'JM example, which is substantially improved in
adhesiveness by modification, obtained a value of about 1 times that of the comparative example.
Next, an example of the honeycomb structure will be described with reference to the drawings. In
FIGS. 2A and 2B, the broom is the modified borifuropyrene of this example? Surface material
used, c! J is a self-contained size of an upper inch and has an aluminum covering of about 20
μm, and has a honeycomb core of 3 cores and a body 1 has a surface layer Q and a
honeycomb core @ bonded in a short time. Heat bath-non-woven fabric grafting agent. A stripshaped sample is cut out from the embodiment of the present invention configured as described
above, and Table 1 shows η 1 1 rule determined by using the −1-1 lead method together with
the metaphorical one. The results in Table 2 Table 2 show that the internal loss of the
embodiment is a very large value of about 25 to 3 times as large as that of Comparative Example
4.5, which was the conventional honeycomb diaphragm. Furthermore, in Comparative Example 1,
the adhesion between the surface material and the core material is not sufficient, and in
Comparative Example 2, the weight is increased because a liquid type adhesive is used, and the
adhesive strength is not sufficient. Furthermore, in the comparative example, it was revealed that
the tendency was lower than that of the example of the present invention because the heat
bonding generates dimples on one surface H and the adhesive strength is not sufficient. As
mentioned above, simply using polypropylene for surface treatment causes problems in the
adhesion of the honeycomb structure. Next, the ノ 第 cam structure of Table 2 was used for the
outer diameter φ 220. Inner diameter φ60. It was formed into a cone-shaped honeycomb
diaphragm of height BOram.
As this forming method, it was formed into the above-mentioned cone shape as a face-up
material, and was further sandwiched using a mold. It has been found that it is difficult and that
the same problem occurs in bonding with edges and spiders when assembled into a speaker. In
addition, although it was considered that nylon, polycarbonate, etc. were made into a surface
facing material other plastics excellent in adhesiveness, these are small with internal loss (eta) or
002-003, and also a density also becomes large. or. As a method of improving the adhesion of
polypropylene, it is conceivable to add fillers such as Merck, mica, glass, etc., but these are
accompanied by an increase in mold needles. As described below, the above-mentioned two
methods I for improving the adhesion, and any method which does not meet the purpose of the
present invention, and improve the adhesion, stretchability, etc. without increasing the growth As
a result, it was found that the method of modifying polypropylene with unsaturated carboxylic
acid was MA. FIG. 3 compares the sound pressure-frequency characteristics of a 30 cm diameter
speaker using the honeycomb diaphragm of one embodiment of the present invention and a
comparative example 4.5. It can be seen that in the present embodiment (the internal loss η of
the go is extremely large compared to the comparative example, and the peak of the high region
is significantly reduced. In the embodiment of the present invention, although 1 polypropylene is
used as the surface material, it is also possible to use modified polypropylene as the core material
and the surface material in this case. It is effective by reducing the peak. As described above, 1)
The present invention uses a modified polypropylene as a face-up material or a surface material
and a core material of a honeycomb structure, thereby having a large internal loss and further
being a honeycomb vibration immersed in welding and forming. It provides a board.
Brief description of the drawings
1A and 1B are a plan view and an enlarged cross-sectional view of a part of a conventional
honeycomb diaphragm, and FIG. 2A, B1'j, and an embodiment of the present invention shown in
FIG. FIG. 3 is a sound pressure-frequency characteristic diagram of the speaker, with a partially
cut away plan view and a preferred RI ≦ enlarged sectional view.
In the figure, the same reference numerals indicate the same or corresponding parts, (1) is a
surface material, (2) is a core material, (3) is an adhesive, and a box is a table 1 size. uJ is a stone
print and (c) is an adhesive. Agent 信 Shin-'II I'll A 2 畠 A