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JP2007208809

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DESCRIPTION JP2007208809
The present invention is to provide an acoustic diaphragm in which physical properties such as
Young's modulus (elastic modulus), tensile strength and the like, as well as excellent propagation
speed and internal loss are enhanced, and a method of manufacturing the same. An acoustic
diaphragm is formed using microfibrillated fibers having an average fiber diameter of 0.002 to 3
μm and an average fiber length of 0.01 to 1 mm. The microfibrillated fiber obtained by
dispersing the raw material fiber in water or an organic solvent, passing through a small
diameter orifice with a pressure difference of at least 300 kg / cm using a high-pressure
homogenizer, colliding with the vessel wall and decelerating rapidly The acoustic diaphragm is
obtained by paper-making using it. [Selected figure] Figure 2
Acoustic diaphragm and method of manufacturing the same
[0001]
The present invention relates to an acoustic diaphragm (diaphragm, center cap, etc.) used for a
speaker or the like and a method of manufacturing the same. In particular, the present invention
relates to an acoustic diaphragm using microfibrillated fibers having an average fiber diameter of
0.002 to 3 μm and an average fiber length of 0.01 to 1 mm, and a method for producing the
same. And a method of producing the same using a microfibrillated fiber obtained by applying a
shear force with a high pressure homogenizer.
[0002]
10-05-2019
1
Acoustic diaphragms, particularly acoustic diaphragms used for speakers, are important
components that greatly affect performance. Since an acoustic diaphragm is required to have a
high longitudinal wave transmission speed, a material which is light and has a large Young's
modulus (elastic modulus) is advantageous, and conventionally paper pulp has been mainly used.
In recent years, materials other than paper, such as polymer materials, metals, and ceramics,
have come to be used as materials for acoustic diaphragms, but they are easy to manufacture,
have appropriate internal losses, and sound quality There are very many materials (type of pulp,
freeness, sizing agents, paper strengthening agents, etc.) corresponding to the factors that affect
the quality of the paper, and it can respond to various sound quality requirements. The rate of
closing is still high, accounting for the majority of acoustic diaphragms.
[0003]
However, in conventional diaphragms mainly made of paper pulp, few can be satisfied in terms
of strength (stiffness) and narrowness of the reproduction frequency band, and in order to
compensate for these drawbacks, for example, JP-A-2001-169387 In the gazette (patent
document 1), mixing ultra-high strength and ultra-high modulus modulus fibers such as aramid
fibers with paper pulp is disclosed. However, the fibrillated fibers and chopped fiber fibers and
the like which are disclosed all use a fiber having a large fiber diameter and therefore have
insufficient binder power, and the more the fibers are compounded, the Young's modulus (elastic
modulus) Tend to cause a decrease in
[0004]
Moreover, the method of using the fibrillated meta-aramid is disclosed by Unexamined-JapanesePatent No. 4-367197 (patent document 2). However, in this method, the manufacturing method
is difficult, and the degree of freedom of raw materials that can be used is low. In addition, since
the degree of refinement is not sufficient in the manufacturing method, it is difficult to obtain a
great effect even if mixed. Patent Document 1: Japanese Patent Application Laid-Open No. 2001169387 Patent Document 4: Japanese Patent Application Laid-Open No. 4-367197
[0005]
The problem to be solved is to provide an acoustic diaphragm having enhanced physical
properties such as Young's modulus (elastic modulus), tensile strength, and excellent propagation
speed and internal loss, and a method of manufacturing the same.
10-05-2019
2
[0006]
The present invention provides (1) an acoustic diaphragm made by forming a microfibrillated
fiber having an average fiber diameter of 0.002 to 3 μm and an average fiber length of 0.01 to 1
mm.
[0007]
The present invention also provides (2) the acoustic diaphragm according to (1), wherein the
average fiber diameter is 0.01 to 1 μm and the average fiber length is 0.01 to 0.7 mm.
[0008]
In the present invention, (3) the microfibrillated fibers disperse raw fibers in water or an organic
solvent, pass through a small diameter orifice with a pressure difference of at least 300 kg / cm
<2> using a high pressure homogenizer, and The acoustic diaphragm as described in (1) or (2)
which is obtained by making it collide and decelerating rapidly is provided.
[0009]
The present invention also provides: (4) The acoustic diaphragm according to any one of (1) to
(3), wherein the microfibrillated fiber or the raw material fiber is a high strength and high
modulus fiber.
[0010]
The present invention also provides: (5) The acoustic diaphragm according to (4), wherein the
high strength and high modulus fiber is a para-based aromatic polyamide.
[0011]
The present invention also provides (6) the acoustic diaphragm according to (5), wherein the
para-based aromatic polyamide is polyparaphenylene terephthalamide.
[0012]
Moreover, this invention, (7) The acoustic diaphragm as described in (3) whose average fiber
length of a raw material fiber is 0.1-5 mm.
10-05-2019
3
[0013]
In the present invention, (8) The acoustic vibration plate comprises microfibrillated fibers and
pulp, and the blending ratio of the microfibrillated fibers to the pulp is 0.1 to 80 wt% on a dry
weight basis (1) to The acoustic diaphragm in any one of (7) is provided.
[0014]
The present invention further comprises the steps of: (9) dispersing raw material fibers of high
strength and high modulus fibers in water or an organic solvent, passing through a small
diameter orifice with a pressure difference of at least 300 kg / cm <2> using a high pressure
homogenizer; The microfibrillated fiber having an average fiber diameter of 0.002 to 3 μm and
an average fiber length of 0.01 to 1 mm is obtained by colliding with a wall and rapidly
decelerating, and using the microfibrillated fiber to form a paper To provide a method of
manufacturing an acoustic diaphragm.
[0015]
According to the present invention, since mixing is carried out using highly microfibrillated
fibers, the entanglement of pulp can be significantly increased, paper strength can be improved,
and physical properties such as tensile strength can be improved. .
Furthermore, since the amount of pulp used can be reduced, the weight can be reduced, the
Young's modulus (elastic modulus) can also be improved, and an acoustic diaphragm with
enhanced propagation speed and internal loss and efficient Method can be provided.
[0016]
Below, the acoustic diaphragm of this invention and its manufacturing method are demonstrated
in detail.
[0017]
The microfibrillated fibers used in the present invention have an average fiber diameter of 0.002
to 3 μm (0.005 to 2 μm), preferably 0.01 to 1 μm (0.02 to 0.8 μm), more preferably 0.2. The
average fiber length is 0.01 to 1 mm, preferably 0.01 to 0.7 mm, and more preferably 0.1 to 0.6
mm. .
10-05-2019
4
The microfibrillated fiber having the above average fiber diameter and average fiber length may
be produced by any method such as homogenizer (high pressure, ultrasonic wave), freeze
grinding, disc refiner, Jordan, beater, rod mill, ball mill, glow mill, etc. Although it may be carried
out (it may be manufactured combining the said method), the method of disperse | distributing a
raw material fiber in water or an organic solvent, and using a high-pressure homogenizer, is used
suitably.
Below, the method to manufacture a microfibrillated fiber using the said high pressure
homogenizer is demonstrated.
[0018]
Disperse the raw material fiber in water or organic solvent, pour the dispersion into the high
pressure homogenizer inlet, pass the small diameter orifice with a pressure difference of at least
300 kg / cm <2>, collide with the vessel wall and decelerate rapidly. Thus, microfibrillated fibers
can be obtained by repeatedly performing an operation of applying a shearing force to the raw
material fibers.
The present method is capable of obtaining microfibril fibers having the same or substantially
the same properties as the raw material fiber except that the shape is changed because physical
processing is performed.
[0019]
Next, the processing method by the high-pressure homogenizer will be described using the
drawings.
[0020]
In FIG. 1, the dispersion flows into the valve device 1 having the valve seat 2 inside in the
direction of the arrow.
10-05-2019
5
As the dispersion enters the small diameter orifice 3 formed in the narrow gap between the valve
4 and the valve seat 2, the speed is rapidly increased by the action of pressure, and between the
inlet and outlet sides of the small diameter orifice 3 A pressure drop occurs.
As the dispersion comes out between the valve 4 and the valve seat 2, it strikes the fitting ring 5
surrounding the orifice and the speed is reduced.
Optionally, the operation is repeated.
The pressure difference and the collision provide a shear force to form the desired
microfibrillated fiber.
The size of the orifice 3 may be any size as long as the raw material fibers in the inflowing
dispersion pass through, but for efficient shearing, it is slightly smaller than the diameter of the
raw material fibers It is preferable to adjust to a large diameter and to carry out.
[0021]
Thus, by applying mechanical shear with a high pressure homogenizer, a microfibrillated fiber
having the above-mentioned average fiber diameter and average fiber length can be obtained.
Furthermore, the ratio (L / D, aspect ratio) of the average fiber length (L) to the average fiber
diameter (D) is 100 to 10,000, preferably 200 to 5,000, more preferably 300 to 3,000, and still
more preferably 400 to It is 2000.
[0022]
The obtained microfibrillated fibrous material may be subjected to a grinding treatment or the
like by a known method to adjust the average fiber length, the average fiber diameter, and the L /
D.
[0023]
10-05-2019
6
The raw material fiber may be any fiber as long as it achieves the shape after microfibrillation,
but organic fibers such as cellulose, aromatic polyamide fibers (polyparaphenylene
terephthalamide, polyparaphenylene -Para-aramid fiber such as 3,4'-diphenylether
terephthalamide, meta-aramid fiber such as polymetaphenylene isophtalamide, etc., polyarylate
fiber, polyphenylene sulfate fiber, polyether ether ketone fiber, polyimide fiber Pyromellitimide
and the like), polybenzazole fiber (polyparaphenylene benzobisoxazole, polyparaphenylene
benzobisthiazole or copolymer thereof, etc.), acrylic fiber and the like can be mentioned.
Among them, in order to increase the rigidity of the sheet-formed body, it is preferable to use a
fiber having high strength and high elastic modulus, and an aromatic polyamide fiber
(polyparaphenylene terephthalamide, polyparaphenylene-3,4'-diphenyl ether) Para-aramid fibers
such as terephthalamide, meta-aramid fibers such as polymetaphenylene isophthalamide),
polyarylate fibers, polyphenylene sulfate fibers, polyimide fibers, polybenzazole fibers
(polyparaphenylene benzobisoxazole, polypara Phenylenebenzobisthiazole or copolymers thereof
are preferred.
Furthermore, aromatic polyamide fibers (para-aramid fibers such as polyparaphenylene
terephthalamide and polyparaphenylene-3,4'-diphenylether terephthalamide, meta-aramid fibers
such as polymetaphenylene isophtalamide, etc.) Among them, polyparaphenylene
terephthalamide is preferable.
[0024]
The fiber length of the raw material fiber is 0.1 to 5 mm, preferably 0.2 to 4 mm, and more
preferably 0.3 to 3 mm.
[0025]
The medium in which the raw material fiber is dispersed is not particularly limited as long as it is
a solution which is inert to the raw material fiber and in which the raw material fiber is
dispersed, but water or an organic solvent is used. Lower alcohols such as phosphite, glycerin,
ethanol and propanol, and ethers such as dimethyl ether are used.
Among them, water is preferably used.
10-05-2019
7
[0026]
The proportion of the raw material fibers dispersed in the solution varies depending on the size
of the apparatus, but the smaller the raw material fiber particle size or the shorter the fiber
length, the higher the raw material fiber concentration can be used.
Usually, the proportion of the raw material fiber in the solution is 10 wt% or less, preferably 0.1
to 8 wt%, more preferably 0.3 to 7 wt%.
[0027]
A dispersion (a liquid in which a raw material fiber is dispersed) is added to a high-pressure
homogenizer at a temperature of 0 to 80 ° C., preferably 1 to 50 ° C. (1 to 30 ° C.), more
preferably 15 to 25 ° C. (normal temperature) The mechanical shear is applied at a pressure
difference of at least 300 kg / cm <2>, preferably 300 to 1000 kg / cm <2>, more preferably 400
to 800 kg / cm <2>. The desired microfibrillated fiber can be obtained by repeating this
operation 1 to 40 times, preferably 3 to 30 times, more preferably 5 to 25 times. The obtained
slurry-like suspension may be used after draining and dewatering.
[0028]
The obtained microfibrillated fibers include various pulps such as commercially available paper
pulp, cotton linter pulp, ramie, hemp, flax, kenaf and the like, but they are preferably
compounded in paper pulp and formed into paper. The blending amount of microfibrillated fiber
to paper pulp can be adjusted as necessary, but it is blended in the range of 0.1 to 80 wt%,
preferably 1 to 70 wt%, more preferably 3 to 60 wt% . If it is less than the above range, the effect
is small in terms of rigidity, propagation speed and internal loss, and if it is more than the above
range, it becomes a heavy sheet-formed body, which may cause deterioration of acoustic
characteristics.
[0029]
10-05-2019
8
A well-known method can be applied to the paper-making method (method for producing an
acoustic diaphragm). For example, a die member (papermaking net) is placed at the bottom of a
papermaking machine, and a slurry in which microfibrillated fibers and paper pulp are dispersed
is fed to the papermaking net to make paper. Next, the papermaking product made of
papermaking is transferred to a drying step, and at this time, the papermaking product may be
transferred as it is to a drying step as a papermaking net, but may be separated from the
papermaking net and transferred to a drying step. In the present invention, since the
microfibrillated fiber is used, the binder strength, ie, the paper strength is significantly improved
as compared with the case where the microfibrillated fiber is not used. Process and can be
streamlined. The paper-made body which passed through the drying process can be used as an
acoustic diaphragm.
[0030]
In addition, carbon fibers, glass fibers, ceramic fibers, ceramic fibers, nylon fibers, cellulose
fibers, polyolefin fibers, super-stretched polyolefin fibers, polyester fibers, etc. are blended as
additives (for example, reinforcing agents) in paper making or after paper making etc. It is also
possible. Also, known paper additives such as so-called sizing agents, for example, acrylamide
type, rosin type and starch type may be added as required. In addition, the rigidity, Young's
modulus, density and the like of the diaphragm can be appropriately adjusted by attaching a
thermoplastic resin, a thermosetting resin or the like to the diaphragm. The method of adding the
sizing agent, thermoplastic resin and thermosetting resin is not particularly limited, and may be
used as a slurry dispersed together with the microfibrillated fibers at the time of paper making,
or it may be dissolved in a solvent depending on the material. Alternatively, the diaphragm may
be attached to the diaphragm by immersing the diaphragm in a suspended solution, or by
spraying an additive (liquid) on the diaphragm.
[0031]
The present invention will be described in more detail based on examples given below, but the
present invention is not limited by these examples.
[0032]
Incidentally, parts or percentages of the compounding ratio are on a weight basis unless
otherwise noted.
10-05-2019
9
The average fiber length and the average fiber diameter were measured by the following
methods.
[0033]
(Average Fiber Length) The average fiber length was measured using a fiber length measurement
device (KAJAANI FS-200).
[0034]
(Average fiber diameter) It observed by magnifying 5000 times using the scanning electron
microscope (JEOL JSM-5500).
An arbitrary place was selected, and the fiber diameter of 10 points was measured by an image
evaluation device to obtain an average fiber diameter.
[0035]
[Example 1] 20 L of water was added to 100 g of a 3 mm chopped fiber of an aromatic
polyamide fiber (Kevlar, manufactured by Toray DuPont Co., Ltd.) as a raw material fiber for
microfibrillation, and stirred well. The obtained dispersion was charged into a high pressure
homogenizer (homogenizing apparatus; 15M-8TA manufactured by GAULIN) at normal
temperature, passed under pressure of 430 kg / cm <2>, and passed 13 times to obtain a slurry.
The slurry was drained to obtain a microfibrillated product with a solid content of 20%. The
obtained microfibrillated fibers had an average fiber length of 0.6 mm and an average fiber
diameter of 0.2 μm. The observation result of this microfibrillated fiber by a scanning electron
microscope is shown in FIG. 15 wt% of this microfibrillated fiber and 85 wt% of paper pulp were
used to make a uniform slurry with a solid content of 1 wt%. The obtained slurry was used for
paper making with an 80 mesh paper making net. Next, the plate was heated and pressed at 130
° C. with a mold having an opening of 83 mm, and dried to form a diaphragm. Next, the density,
Young's modulus, propagation velocity and internal loss of the obtained sheet-formed body
(acoustic diaphragm) are shown in Table 2.
[0036]
10-05-2019
10
Example 2 The procedure of Example 1 was repeated except that the raw material fiber for
microfibrillation of Example 1 was changed to 100 g of 3 mm chopped fiber of
polymetaphenylene isophthalamide fiber (manufactured by Teijin Ltd .; Cornex). Physical
properties and acoustic characteristics of the obtained sheet-formed body (acoustic diaphragm)
are shown in Table 2.
[0037]
Example 3 The procedure of Example 1 was repeated except that the raw material fiber for
microfibrillation of Example 1 was changed to 100 g of 3 mm chopped fiber of polyarylate fiber
(manufactured by Kuraray; Bectran). Physical properties and acoustic characteristics of the
obtained sheet-formed body (acoustic diaphragm) are shown in Table 2.
[0038]
Example 4 The procedure of Example 1 was repeated except that the raw material fiber for
microfibrillation of Example 1 was 100 g of polyphenylene sulfide fiber (Toyobo Co., Ltd .;
Procon) cut to a cut length of 3 mm. Physical properties and acoustic characteristics of the
obtained sheet-formed body (acoustic diaphragm) are shown in Table 2.
[0039]
Example 5 The procedure of Example 1 was repeated except that the raw material fiber for
microfibrillation of Example 1 was made into 100 g of a polyimide fiber (Toyobo Co., Ltd .; P84)
cut to a cut length of 3 mm. Physical properties and acoustic characteristics of the obtained
sheet-formed body (acoustic diaphragm) are shown in Table 2.
[0040]
Comparative Example 1 An acoustic vibration plate was prepared in the same manner as in
Example 1 using 100 wt% of paper pulp used in Example 1 (without using microfibrillated fibers)
10-05-2019
11
without performing high-pressure homogenizer treatment. Physical properties and acoustic
characteristics of the obtained acoustic diaphragm are shown in Table 2.
[0041]
[Comparative Example 2] 15 wt% of chopped fiber 3 mm of aromatic polyamide fiber (Kevlar
manufactured by Toray Dupont Co., Ltd.) and 85% of paper pulp were mixed without high
pressure homogenizer treatment, and sound was produced in the same manner as Example 1. I
made a diaphragm. Physical properties and acoustic characteristics of the obtained acoustic
diaphragm are shown in Table 2.
[0042]
The average fiber length and average fiber diameter of the microfibrillated fibers obtained in
Examples 1 to 5 and the fibers used in Comparative Example 2 are shown in Table 1.
[0043]
[0044]
As apparent from Table 2, it is possible that the acoustic diaphragm made using the
microfibrillated fiber having the average fiber length and the average fiber diameter of the
present invention has acoustic properties excellent in Young's modulus, propagation speed, and
internal loss. Recognize.
[0045]
The acoustic diaphragm (diaphragm, center cap, etc.) of the present invention is an acoustic
diaphragm excellent in tensile strength and Young's modulus (elastic modulus) and excellent in
internal loss and propagation speed, and the manufacturing method is also simple. Therefore, it
can be widely used.
[0046]
It is a figure of a high pressure homogenizer apparatus.
10-05-2019
12
It is the observation result by the scanning electron microscope (5000 times of magnification) of
the microfibrillated fiber obtained by Example 1. FIG.
Explanation of sign
[0047]
1 valve device 2 valve seat 3 small diameter orifice 4 valve 5 fitting ring
10-05-2019
13
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