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Description 1, title of the invention
Acoustic material
8. Detailed description of the invention The present invention relates to an acoustic material, and
in particular, the acoustic velocity is large, and by changing the composition, the acoustic velocity
is kept relatively large and the acoustic loss is large or the manufacture is easy. It is intended to
provide an acoustic material that can be The eight sound components such as the diaphragm and
the tone arm for the player are required to be materials having high sound velocity, light weight
and appropriate acoustic loss. In particular, the diaphragm is required to have a large acoustic
loss. The speed of sound is proportional to the square root of the specific modulus (modulus /
density), so a light, high modulus material is desired. Furthermore, in the diaphragm, in order to
suppress split vibration, two-dimensional strength and not strength in one axial direction is
required. When considering, for example, a diaphragm as an acoustic component, conventionally,
paper, resin, paper mixed with carzane fiber, paper mixed with aromatic polyamide fiber, carzane
fiber, alumina fiber, etc., aluminum alone, aluminum alloy Single plates, titanium single plates,
steel IJ +), single plates made of foam metal, etc. are used, but it is far from being satisfactory. In
general, materials other than acoustic materials consisting of a single metal are referred to as
composite acoustic materials. Non-explosion qn Kono 'f5 JEndPage: 1 related to the acoustic
material. In terms of diaphragms, composite acoustic materials generally have high acoustic loss
and are desirable as diaphragms, but have a low speed of sound. For example, although the
carbon fiber itself has a large sound velocity, in a composite material in which the carbon fiber is
bonded with a resin, there is a problem that the carbon fiber is broken at the time of shaping and
a sound velocity as expected can not be obtained. Also, the speed of sound is small even with
carbon fiber mixed paper. Aluminum and titanium diaphragms have a relatively low speed of
sound, as well as low acoustic losses, which is inadequate. Titanium diaphragms are also
expensive. A single beryllium diaphragm is desirable because of its high sound velocity, but it
also has low acoustic losses, is very expensive, and has manufacturing problems because it is
toxic. The diaphragm of single boron plate is the highest among the known materials in sound
speed, which is desirable, but if it is as it is, the problem is that the price is slightly high, the
acoustic loss is large, and some device is necessary. is there. A diaphragm in which mica pieces
are laminated with resin is known as a solution to the extent that such a problem is caused. Is
this scaly mica? They are two-dimensionally strong, and they have higher sound velocity than
aluminum diaphragms and smaller acoustic loss. L or L while the speed of sound is insufficient.
Furthermore, when considering a tone arm as another example of the acoustic material, those
made of aluminum or aluminum alloy, titanium, titanium whose surface is nitrided, carbon fiber
reinforced resin, etc. are known at present. In this field, how is the requirement for acoustic loss
not so severe for the diaphragm? Except for the above, it is almost the same as the above. The
present invention eliminates the disadvantages of the conventional acoustic materials as
described above, and also provides a composite material in which the scaly materials are more
closely laminated. In the present invention, pieces of aluminum boride, especially pieces mainly
composed of monoaluminum diboride (A # E2), are laminated and fixed with resin, or aluminum
boride into other fibrous or scaly materials In particular, the whole of the acoustic material is
obtained by mixing together, laminating, and resin-fixing the flakes, especially the flakes mainly
composed of AlB2. At this time, the reason for adding another fibrous material or scale-like
material is mainly to adjust the acoustic loss and obtain one or a dense laminated state. l! As
for the acoustic material, although the degree of the requirement for acoustic loss varies
depending on the application in the acoustic field, according to the present invention, the
acoustic loss can be adjusted by changing the composition of the materials to be mixed. Table 1
shows the velocities of sound of various materials. A scale of aluminum boride, particularly a
scale consisting of AlB 2, is very excellent in sound velocity compared to mica etc., and its density
is as small as 2.9 f / afr, which is preferable as an acoustic material. Further, the aspect ratio of
the scale piece is about 10 to about 10,000, and when it is laminated and solidified, the bending
strength is two-dimensionally large, and it is very useful particularly for applications such as a
diaphragm. The preferred aspect ratio of aluminum boride can vary naturally depending on the
application of the acoustic product. The desired aspect ratio of aluminum boride flakes can be
screened by sieve if desired. The resin to be fixed can be changed depending on the application
field of the acoustic product, adjustment of acoustic loss, fixing method and the like, but the
speed of sound of the acoustic material is mainly determined by the scale. The ratio between the
resin and the flakes is determined by the mechanical strength, sound velocity, acoustic loss, type
of resin, difficulty of the fixing process, and the weight ratio of the flake to resin is 75. The range
of / 15 to 50150 is desirable. The step of fixing the flakes laminated with the resin is performed
by impregnating the flakes with the resin, followed by pressing, and if necessary, heating. In
addition, it will be understood that, as a result of elemental analysis of the aluminum boride
flakes, the composition of aluminum and boron is approximately 1: 2 in atomic ratio.
Also, according to the description of Gumerin et al., It is judged that the appearance mainly
consists of AlB2. Also, from the results of X-ray diffraction, the AlB2 line and the AlB12 line are
observed. When the scales were washed well, the A6B12 line became weak. Next, the case where
a fibrous material or other material which becomes the composite acoustic material component
other than the scaly brazed aluminum is added is described. The addition of these materials may
reduce the speed of sound of the composite acoustic material slightly, but a dense lamination is
obtained (especially in the case of asbestos fibers and mica), which is effective in increasing the
acoustic loss. . As such a material, as fibers, alumina fibers, asbestos fibers, glass fibers, carbon
fibers, alumina fibers, and as flakes, mica (mica) pieces, flake-like graphite, flake-like glass and
the like are preferable. In addition, inorganic powder such as glass powder may be added to
these because of the difficulty in manufacturing the composite acoustic material, for example, the
fluidity of the mixture of aluminum hydride and resin resin. However, the amount of addition can
not be much because of the characteristics of the composite acoustic material. This is because
the properties such as the sound velocity and the bending strength of the composite acoustic
material depend on aluminum boride pieces, other scale-like materials and fiber materials. Next,
one experimental example of the manufacturing process of the plate-like acoustic material
according to the present invention will be described. First of all, use a sieve to sort the brazed
aluminum flakes of 0.5 or more questions in the radial direction. The thickness of the scale in
this case is 5 microns or less. Next, 2 grams of the above flakes are dispersed in water, and this
mixed system is poured on a filter paper and sucked for 1 L overpass L 1 and then dried. In this
way, the flakes are laminated on the filter paper. The following [0, 85 grams of epoxy resin
(manufactured by Shell Chemical, Epicoat 828, mixed by Kayahart, manufactured by Nippon
Chemical Co., Ltd.) is poured, and the flakes are impregnated. Next, carefully peel off the plate of
epoxy resin impregnated flakes from the filter paper, and sandwich this plate from above and
below with a Teflon sheet. Subsequently, it is heated at 180 ° C. for 1 hour while pressing L.
Then, heat at 60 ° C for 1 hour, peel off the Teflon sheets on both sides, and adjust the shape to
a sample plate? obtain. The sheet metal is vibrated in this way, the Young's modulus is calculated
from its resonant frequency, and the speed of sound from this and the density of the plate? The
calculated results are shown in sample 1 of Table 2. Sample 2 in Table 2 is 2 g of a blanched
aluminum flake for sample 1 [0, 3 clamno asbestos fiber?
In addition, it was prepared in the same manner as Sample 1. As compared with the cross section
of sample 1, it was observed that the cross sections of sample 2 were more closely stacked in
scale pieces. Samples 3 and 4 are examples given for comparison. As described above, the
composite acoustic material using the aluminum boride piece has a high sound velocity, and the
acoustic loss is in an appropriate range. In Table 2, Q is proportional to the reciprocal of the
acoustic loss. Although not shown in the examples, in the case of the composite acoustic material,
the sound velocity decreases and the Q decreases as the resin content increases. Therefore, by
controlling the amount of resin component, the speed of sound and Q can be made appropriate.
In addition, when scaly and fibrous materials other than asbestos fibers are added together with
the aluminum scorch, the acoustic loss increases. Therefore, this can be adjusted to adjust Q, and
the lamination state of the aluminum flakes can be improved. Also, even if the type of resin is
changed, it is possible to adjust the acoustic properties of aluminum hydride flakes or aluminum
fluoride flakes to which other composite acoustic materials are added and laminated and fixed to
desired ones. You can get the best. As described above, according to the present invention, it is
possible to obtain a composite acoustic material having a high sound velocity, an appropriate
acoustic loss, and being easy to manufacture. Table 1 EndPage: 3 Table 2 Name of Agent
Attorney Attorney Yoshizaki Koji 508-EndPage: 4