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DESCRIPTION JP2016219804

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DESCRIPTION JP2016219804
Abstract: To provide an organic piezoelectric film in which the piezoelectric in-plane variation is
particularly small. An organic piezoelectric film having a variation coefficient of a piezoelectric
constant d of 50% or less is a film (polymer film) formed of a polymer which is an organic
substance. Examples include polarized vinylidene fluoride polymer films, odd-chain nylon
piezoelectric films and polylactic acid. The organic piezoelectric film may contain components
other than the polymer. The organic piezoelectric film also includes a film made of the polymer
and a film in which an inorganic substance is dispersed in the polymer. 【Selection chart】 None
Organic piezoelectric film
[0001]
The present invention relates to an organic piezoelectric film.
[0002]
Conventionally, various organic piezoelectric films and inorganic dielectric films are known as
films or films having piezoelectricity.
Among them, the organic piezoelectric film has an advantage of being flexible unlike an inorganic
dielectric film, and therefore, can be applied to various applications. For example, Patent
Document 1 discloses, as a piezoelectric film, a polarized vinylidene fluoride / tetrafluoroethylene
copolymer film for touch panel or touch pressure detection.
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[0003]
In recent years, electronic devices provided with a touch panel instead of a mechanical button as
an input member are increasing from the advantage of excellent operability. However, in the case
of the mechanical button, the user can obtain an operation feeling when the button is moved, but
there is a disadvantage that the touch panel can not obtain such an operation feeling. In order to
eliminate such disadvantages, a touch panel provided with a flexible piezoelectric actuator has
been proposed in which tactile feedback is provided to a user who operates the touch panel (for
example, Patent Document 2). An apparatus using such a technology for feedbacking a sense of
touch to a user who operates a touch panel is generally referred to as a haptic device.
[0004]
On the other hand, mobile electronic devices such as smartphones and tablets are equipped with
a secondary battery because they are carried by the user. In order to reduce the frequency of
charging, a vibration power generation device using a piezoelectric element, which can be used
for such an electronic device or the like, has been proposed (Patent Document 3).
[0005]
The piezoelectric film is a piezoelectric element that is easy to process and has a large area and
can be easily thinned. A dynamic pressure sensor having a large area and high voltage sensitivity
can be manufactured as compared with a conventional ceramic piezoelectric element. For
example, it is used as a pressure sensor that detects a load applied to a resilient support such as a
bed, mat, or sheet, and determines the presence or absence of a person, an animal, an object, or
the like.
[0006]
In recent years, research on a flexible display using a flexible substrate such as plastic has been
advanced. As a substrate of such a flexible display, for example, Patent Document 4 discloses a
flexible display substrate in which a gas barrier layer and a transparent conductive layer are
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laminated on a transparent plastic film. The flexible display has advantages in lightness, thinness,
flexibility and the like as compared with a display using a conventional glass substrate, and
therefore can be installed on a curved surface such as a cylinder. Furthermore, since it can be
rolled and stored, there is no loss of portability even with a large screen. Because of these
advantages, flexible displays are attracting attention, for example, in applications for posting
advertisements and the like, and for display devices such as PDAs (personal digital assistants).
When such a flexible display is used as an image display device / voice generation device that
reproduces voice as well as images as a television receiver or the like, a speaker that is an
acoustic device for generating voice is required. Here, as a conventional speaker shape, a funnelshaped so-called cone shape, a spherical dome shape and the like are generally used. However,
incorporating these speakers in the above-described flexible display may impair the advantages
of the flexible display, such as lightness and flexibility. On the other hand, when the speaker is
externally attached, it may not be easy to carry, etc., may be difficult to install on a curved wall,
and may cause disadvantages such as a loss of aesthetics. In such background, it is disclosed in,
for example, Patent Document 5 that a sheet-like flexible piezoelectric film is employed as a
speaker that can be integrated into a flexible display without loss of lightness and flexibility. It is
done.
[0007]
JP, 2011-222679, JP, 2003-288158, JP, 2011-97661, JP, 2000-338901, JP, 2008, 294493
[0008]
In recent years, a touch panel with a larger screen is required.
Therefore, in a touch panel capable of touch pressure detection, it is desirable that a piezoelectric
film used for touch pressure detection also have a large screen. However, when the conventional
piezoelectric film is used for such a large screen touch panel, the small in-plane variation of the
piezoelectric property is not sufficient. Specifically, when the small in-plane variation of the
piezoelectricity of the organic piezoelectric film used for a touch panel (particularly, a largescreen touch panel) capable of detecting a touch pressure is not sufficient, the touch position is
obtained even with the same pressure. Since the electric signal generated by the signal fluctuates,
there is a problem that the device judges that the pressure is different and a malfunction occurs.
[0009]
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In addition, when the conventional piezoelectric film is used for a haptic device, the small inplane variation of piezoelectricity is not sufficient. Specifically, when the small in-plane variation
of the piezoelectricity of the organic piezoelectric film used for the haptic device is not sufficient,
variation occurs in the feedback to be feedback, and a stable feeling of operation can not be
obtained, and an operation error, And there is a problem of causing malfunction of the device.
[0010]
Moreover, when the conventional piezoelectric film is used for a vibration power generation
device, the small in-plane variation of piezoelectricity was not enough. Specifically, when the
small in-plane variation of the piezoelectricity of the organic piezoelectric film used in the
vibration power generation device is not sufficient, a constant and stable power generation
amount can not be obtained even if the vibration amount is the same. There's a problem.
[0011]
In addition, when the small in-plane variation of the piezoelectricity of the organic piezoelectric
film used for a pressure sensor (in particular, a large area pressure sensor) is not sufficient, an
electric signal generated depending on the position to which pressure is applied even with the
same pressure. The problem is that sensing becomes unstable because
[0012]
In addition, when the small in-plane variation of the piezoelectricity of the organic piezoelectric
film used for a flat speaker (in particular, a flat speaker with a large area) is not sufficient, the
sound generated varies depending on the in-plane location, so the sound quality is degraded.
Have the problem of
[0013]
Therefore, an object of the present invention is to provide an organic piezoelectric film in which
the piezoelectric in-plane variation is particularly small.
[0014]
As a result of intensive studies, the present inventors have found that the problem can be solved
by an organic piezoelectric film having a coefficient of variation of piezoelectric constant d 33 of
50% or less, and has completed the present invention.
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[0015]
The present invention includes the following aspects.
[0016]
Item 1.
The organic piezoelectric film whose coefficient of variation of piezoelectric constant d33 is 2.0
or less.
Item 2.
Item 2. The organic piezoelectric film according to item 1, wherein the piezoelectric constant d
33 is in the range of 0.5 to 30 pC / N.
Item 3.
Item 2. The organic piezoelectric film according to item 1, wherein the piezoelectric constant d
33 is in the range of less than 0.5 to 2.0 pC / N. Item 4. 2. The organic piezoelectric film
according to item 1, wherein the piezoelectric constant d 33 is in the range of less than 2.0 to 4.0
pC / N, and the coefficient of variation is 1.0 or less. Item 5. 2. The organic piezoelectric film
according to item 1, wherein the piezoelectric constant d 33 is in the range of less than 4.0 to 6.0
pC / N, and the coefficient of variation is 0.6 or less. Item 6. 2. The organic piezoelectric film
according to item 1, wherein the piezoelectric constant d 33 is in the range of less than 6.0 to
10.0 pC / N, and the coefficient of variation is 0.4 or less. Item 7. The organic piezoelectric film
according to item 1, wherein the piezoelectric constant d 33 is in the range of less than 10.0 to
14.0 pC / N, and the coefficient of variation is 0.3 or less. Item 8. The organic piezoelectric film
according to item 1, wherein the piezoelectric constant d 33 is in the range of 14.0 to 30.0 pC /
N, and the coefficient of variation is 0.15 or less. Item 9. Item 9. The organic piezoelectric film
according to any one of Items 1 to 8, wherein the tensile modulus of elasticity is in the range of
0.4 to 5 GPa. Item 10. Item 10. The organic piezoelectric film according to any one of Items 1 to
9, which has a retardation of 200 to 10000 nm. Item 11. The organic piezoelectric film according
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to any one of Items 1 to 9, wherein the retardation is in the range of 0.5 to 200 nm. Item 12.
Item 12. The organic piezoelectric film according to any one of Items 1 to 11, which comprises a
polarized vinylidene fluoride polymer film. Item 13. Item 12. The organic piezoelectric film
according to any one of items 1 to 12, wherein the internal haze value is in the range of 0.05 to
80%. Item 14. Item 12. The organic piezoelectric film according to any one of items 1 to 12,
wherein the internal haze value is in the range of 5 to 90%. Item 15. Item 14. A piezoelectric
panel having the organic piezoelectric film according to any one of items 1 to 14 (preferably, the
organic piezoelectric film according to any one of items 1 to 13). Item 16. A pressure sensor
comprising the organic piezoelectric film according to any one of items 1 to 14 (preferably, the
organic piezoelectric film according to any one of items 1 to 12 and 14). Item 17. Item 15. A
haptic device having the organic piezoelectric film according to any one of items 1 to 14
(preferably, the organic piezoelectric film according to any one of items 1, 2, 5 to 12, and 14).
Item 18. The vibration electric power generation device which has an organic piezoelectric film
of any one of claim | item 1-14 (preferably, the organic piezoelectric film of any one of claim |
item 1, 2, 5-12, and 14).
Item 19. A planar speaker having the organic piezoelectric film according to any one of items 1
to 14 (preferably, the organic piezoelectric film according to any one of items 1, 2, 5 to 12, and
14).
[0017]
According to the present invention, an organic piezoelectric film having a small in-plane variation
of piezoelectricity is provided. The organic piezoelectric film of the present invention is excellent
in that malfunction does not easily occur, for example, when used for a touch pressure detectable
touch panel (especially when used for a large area touch pressure detectable touch panel) . In
addition, the organic piezoelectric film of the present invention is excellent in that stable sensing
can be realized, for example, when used for a pressure sensor (particularly, even when used for a
large area pressure sensor). In addition, the organic piezoelectric film of the present invention is
excellent in that when it is used for a haptic device, for example, operation errors and device
malfunction are less likely to occur. In addition, the organic piezoelectric film of the present
invention is excellent in that when used in, for example, a vibration power generation apparatus,
a constant and stable power generation amount can be obtained. In addition, the organic
piezoelectric film of the present invention is excellent in that high sound quality can be obtained,
for example, when used for a flat speaker (particularly, even when used for a large area flat
speaker).
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[0018]
FIG. 16 is a schematic view showing an outline of a production apparatus used for producing the
organic piezoelectric film of Example 3.
[0019]
Terms Unless otherwise stated, the symbols and abbreviations in the present specification are
understood in the context of the present specification and in the meaning generally used in the
technical field to which the present invention belongs.
As used herein, the term "comprising" is used with the intention of including the terms
"consisting essentially of" and "consisting of." In the present specification, "detection" of "touch
position" means determination of touch position, while "detection" of "touch pressure" means
determination of presence / absence of pressure, speed, size or a combination thereof. means. As
used herein, the term "touch" includes touching, touching, pushing, pushing and touching. As
used herein, the term "polarization" means that the surface is charged. That is, the polarized film
can be an electret. As used herein, the term "haptic device" means a device having the ability to
provide tactile feedback to the user. Unless otherwise stated, the symbols and abbreviations in
the present specification are understood in the meaning generally used in the technical field to
which the present invention belongs, in the context of the present specification. As used herein,
"variation value" is the ratio of standard deviation / arithmetic mean.
[0020]
Organic Piezoelectric Film The organic piezoelectric film of the present invention is an organic
piezoelectric film having a variation coefficient of piezoelectric constant d 33 of 2.0 or less.
Hereinafter, the organic piezoelectric film of the present invention will be described in detail.
[0021]
The organic piezoelectric film of the present invention is a film (polymer film) formed of a
polymer which is an organic substance. Examples of the "organic piezoelectric film" include a
polarized vinylidene fluoride polymer film, an odd-chain nylon piezoelectric film, and polylactic
acid. The "organic piezoelectric film" may contain components other than the polymer. The said
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"organic piezoelectric film" includes the film which consists of the said polymer, and the film by
which the inorganic substance is disperse | distributed in the said polymer. The content of the
polymer (that is, the polymer forming the organic piezoelectric film of the present invention) in
the organic piezoelectric film of the present invention is preferably 80% by mass or more, more
preferably 85% by mass or more, still more preferably 90 It is mass%. The upper limit of the
content is not particularly limited, and may be, for example, 100% by mass or 99% by mass. The
polymer is preferably a vinylidene fluoride polymer. The organic piezoelectric film of the present
invention preferably comprises a polarized vinylidene fluoride-based polymer film. In the present
specification, examples of the “vinylidene fluoride polymer film” include vinylidene fluoride /
tetrafluoroethylene copolymer film, vinylidene fluoride / trifluoroethylene copolymer film, and
polyvinylidene fluoride film. It can be mentioned. The vinylidene fluoride polymer film is
preferably a vinylidene fluoride / tetrafluoroethylene copolymer film. The said "vinylidene
fluoride type polymer film" may contain the additive normally used for a resin film.
[0022]
The said "vinylidene fluoride polymer film" is a film comprised from a vinylidene fluoride
polymer, and contains a vinylidene fluoride polymer.
[0023]
Examples of the "vinylidene fluoride polymer" include (1) a copolymer of vinylidene fluoride and
one or more monomers copolymerizable therewith; and (2) polyvinylidene fluoride
[0024]
Examples of the “monomer copolymerizable therewith” in the “(1) copolymer of vinylidene
fluoride and one or more monomers copolymerizable therewith” include trifluoroethylene and
tetrafluoroethylene. Hexafluoropropylene, chlorotrifluoroethylene, and vinyl fluoride.
The “one or more monomers copolymerizable therewith” or one of them is preferably
tetrafluoroethylene.
As a preferable example of the said "vinylidene fluoride type polymer", a vinylidene fluoride /
tetrafluoro ethylene copolymer is mentioned. The "vinylidene fluoride / tetrafluoroethylene
copolymer" may contain repeating units derived from monomers other than vinylidene fluoride
and tetrafluoroethylene, as long as the properties relating to the present invention are not
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significantly impaired. The “(1) copolymer of vinylidene fluoride and one or more monomers
copolymerizable therewith” has 50 mol% or more (preferably 60 mol% or more) of repeating
units derived from vinylidene fluoride )contains. The molar ratio of (repeating unit derived from
tetrafluoroethylene) / (repeating unit derived from vinylidene fluoride) in the above “vinylidene
fluoride / tetrafluoroethylene copolymer” is preferably 5/95 to 36/64 It is in a range, more
preferably in a range of 15/85 to 25/75, further preferably in a range of 18/82 to 22/78.
[0025]
The “vinylidene fluoride / tetrafluoroethylene copolymer” may contain repeating units derived
from monomers other than vinylidene fluoride and tetrafluoroethylene, as long as the properties
relating to the present invention are not significantly impaired. Usually, the content of such
repeating units is 10 mol% or less. Such monomers are not limited as long as they are
copolymerizable with vinylidene fluoride monomers and tetrafluoroethylene monomers, and
examples thereof include (1) fluoromonomers (eg, vinyl fluoride (VF), trifluoro Ethylene (TrFE),
hexafluoropropene (HFP), 1-chloro-1-fluoro-ethylene (1,1-CFE), 1-chloro-2-fluoro-ethylene (1,2CFE), 1-chloro- 2,2-Difluoroethylene (CDFE), chlorotrifluoroethylene (CTFE), trifluorovinyl
monomer, 1,1,2-trifluorobutene-4-bromo-1-butene, 1,1,2-trifluorobutene -4-silane-1-butene,
perfluoroalkyl vinyl ether, perfluoromethyl vinyl ether (PMVE), perfluoropropyl vinyl ether
(PPVE), perfluoroacrylate, 2,2,2-trifluoroethyl acrylate, 2- (perfluorohexyl) ethyl acrylate); and (2)
hydrocarbon-based monomer (eg, ethylene) And propylene, maleic anhydride, vinyl ether, vinyl
esters, allyl glycidyl ether, acrylic acid monomers, methacrylic acid monomers, and vinyl acetate.
[0026]
As a suitable example of the above-mentioned "inorganic substance", inorganic oxide particles are
mentioned. By containing the "inorganic oxide particles", the high dielectric film of the present
invention can have a high dielectric constant. In addition, this makes it possible to significantly
improve the volume resistivity while maintaining a high dielectric constant.
[0027]
As a suitable example of the above-mentioned "inorganic substance", inorganic oxide particles are
mentioned. By containing the "inorganic oxide particles", the organic piezoelectric film of the
present invention can have a high dielectric constant. In addition, the volume resistivity can be
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greatly improved while maintaining a high dielectric constant. In addition, electrical insulation
can be improved.
[0028]
The “inorganic oxide particles” are preferably at least one selected from the group consisting
of inorganic oxide particles (B1) to (B3) below.
[0029]
[Inorganic Oxide Particles (B1)] Particles of inorganic oxides of metal elements of Groups 2, 3, 4,
12, or 13 of the periodic table, or inorganic oxide composite particles of these as the metal
element, Examples include Be, Mg, Ca, Sr, Ba, Y, Ti, Zr, Zn, and Al.
Among them, oxides of Al, Mg, Y, and Zn are preferable because they are general-purpose,
inexpensive and have high volume resistivity. Among them, specifically, particles of at least one
metal oxide selected from the group consisting of Al 2 O 3, MgO, ZrO 2, Y 2 O 3, BeO, and MgO ·
Al 2 O 3 have a volume of It is preferable from the point of high resistivity. Among them, Al 2 O
3 having a crystal structure of γ type has a large specific surface area, and is dispersed in the
above “polymer” such as vinylidene fluoride polymer, particularly vinylidene fluoride /
tetrafluoroethylene copolymer. It is preferable from the point of good nature.
[0030]
[Inorganic oxide particles (B2)] Formula: M <1> a1 M <2> b1 O c1 (wherein, M <1> is a Group 2
metal element; M <2> is a Group 4 metal element; a1 Is 0.9 to 1.1; b1 is 0.9 to 1.1; c1 is 2.8 to
3.2; M <1> and M <2> are respectively 1 type or 2 Particles of Inorganic Complex Oxide
Represented by More Kinds of Metal Elements) As the “group 4 metal element”, for example,
Ti and Zr are preferable. As the said "group 2 metal element", Mg, Ca, Sr, and Ba are preferable,
for example. Among the “particles of inorganic complex oxide”, specifically, at least one
selected from the group consisting of BaTiO 3, SrTiO 3, CaTiO 3, MgTiO 3, BaZrO 3, SrZrO 3,
CaZrO 3, and MgZrO 3. Particles of inorganic oxide of a species are preferred in view of high
volume resistivity.
[0031]
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[Inorganic oxide particles (B3)] Inorganic oxide composite particles of oxides of metal elements of
Groups 2, 3, 4, 12, 12 or 13 of the periodic table, and silicon oxide B3) is a composite particle of
the “inorganic oxide” of the “inorganic oxide particle (B1)” and silicon oxide. Specifically as
the “inorganic oxide particles (B3)”, at least one selected from the group consisting of 3A1 2 O
3 .2SiO 2, 2MgO · SiO 2, ZrO 2 · SiO 2, and MgO · SiO 2, for example Some inorganic oxide
particles are included.
[0032]
The “inorganic oxide particles” do not necessarily have to have high dielectric properties, and
can be appropriately selected according to the application of the organic piezoelectric film of the
present invention. For example, the volume resistivity can be improved by using a generalpurpose low-cost metal oxide particle (B1) (in particular, a particle of Al 2 O 3 and a particle of
MgO). The relative dielectric constant (1 kHz, 25 ° C.) of the particles (B1) of one kind of metal
oxide is usually less than 100, preferably 10 or less.
[0033]
As the "inorganic oxide particles", inorganic oxide particles (for example, inorganic oxide particles
(B2)) having ferroelectricity (specific dielectric constant (1 kHz, 25 ° C.) of 100 or more) for the
purpose of improving the dielectric constant And (B3)) may be used. Examples of the inorganic
material constituting the ferroelectric inorganic oxide particles (B2) and (B3) include composite
metal oxides, composites thereof, solid solutions, sol-gel bodies, etc., but are limited thereto is
not.
[0034]
The organic piezoelectric film of the present invention can contain 0.01 to 300 parts by mass,
more preferably 0.1 to 100 parts by mass of the "inorganic oxide particles" per 100 parts by
mass of the "polymer". . If the content of the “inorganic oxide particles” is too large, it may be
difficult to uniformly disperse the “inorganic oxide particles” in the “polymer”, and the
electrical insulation (withstand voltage) ) May decrease. If the content is 300 parts by mass or
more, the film may become brittle and the tensile strength may be reduced. In this respect, the
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upper limit of the content is preferably 200 parts by mass, more preferably 150 parts by mass. If
the content is too small, it is difficult to obtain the effect of improving the electrical insulation. In
this respect, the lower limit of the content is preferably 0.1 parts by mass, more preferably 0.5
parts by mass, and still more preferably 1 part by mass. On the other hand, when high total light
transmittance and low total haze value are required for the organic piezoelectric film of the
present invention, the content is preferably smaller, and further, particularly to the organic
piezoelectric film of the present invention, When a high total light transmittance and a low total
haze value are required, the organic piezoelectric film of the present invention can suitably
contain no "inorganic oxide particles". As described above, when the organic piezoelectric film of
the present invention requires a high total light transmittance and a low total haze value,
specifically, the organic piezoelectric film of the present invention may be used for a piezoelectric
panel such as a touch panel. It can be mentioned.
[0035]
The average primary particle diameter of the "inorganic oxide particles" is preferably smaller,
and particularly so-called nanoparticles having an average primary particle diameter of 1 μm or
less are preferable. By uniformly dispersing such inorganic oxide nanoparticles, it is possible to
significantly improve the electrical insulation of the film with a small amount of blending. The
average primary particle size is preferably 800 nm or less, more preferably 500 nm or less, and
still more preferably 300 nm or less. The lower limit of the average primary particle size is not
particularly limited, but the average primary particle size is preferably 10 nm or more, more
preferably 20 nm or more, and still more preferably from the viewpoint of production difficulty,
difficulty in uniform dispersion, and price. 50 nm or more. Here, when a high total light
transmittance and a low total haze value are required for the organic piezoelectric film of the
present invention, the average primary particle size is preferably smaller. The average primary
particle diameter of the “inorganic oxide particles” is calculated using a laser diffraction /
scattering type particle size distribution measuring apparatus LA-920 (trade name) (Horiba, Ltd.)
or an equivalent thereof.
[0036]
The relative permittivity (25 ° C., 1 kHz) of the “inorganic oxide particles” is preferably 10 or
more. From the viewpoint of increasing the dielectric constant of the piezoelectric film, the
relative dielectric constant is preferably 100 or more, more preferably 300 or more. The upper
limit of the relative dielectric constant is not particularly limited, but is usually about 3,000. The
relative dielectric constant (ε) (25 ° C., 1 kHz) of the “inorganic oxide particles” is measured
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for capacity (C) using an LCR meter, and the capacity, electrode area (S), thickness of sintered
body From (d), it is the value calculated by the formula C = εε 0 × S / d (ε 0 vacuum
permittivity).
[0037]
The organic piezoelectric film of the present invention may optionally contain other components
such as an affinity improver.
[0038]
The "affinity improvement agent" is contained in the organic piezoelectric film of the present
invention when the organic piezoelectric film of the present invention contains the "inorganic
oxide particles".
The “affinity improver” enhances the affinity between the “inorganic oxide particles” and
the “polymer”, and uniformly disperses the “inorganic oxide particles” in the “polymer”,
The “inorganic oxide particles” and the “polymer” can be firmly bonded in a film to
suppress the generation of voids and to increase the dielectric constant.
[0039]
As the above-mentioned "affinity improvement agent", a coupling agent, a surfactant or an epoxy
group-containing compound is effective.
[0040]
Examples of the aforementioned "coupling agent" include organic titanium compounds, organic
silane compounds, organic zirconium compounds, organic aluminum compounds, and organic
phosphorus compounds.
[0041]
Examples of the aforementioned "organic titanium compound" include coupling agents such as
alkoxytitanium, titanium chelate, and titanium acylate.
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Among them, alkoxytitanium and titanium chelate are mentioned as preferable examples from
the viewpoint of good affinity to the above-mentioned "inorganic oxide particles".
[0042]
Specific examples thereof include tetraisopropyl titanate, titanium isopropoxy octylene glycolate,
diisopropoxy bis (acetylacetonato) titanium, diisopropoxy titanium diisostearate, tetraisopropyl
bis (dioctyl phosphite) titanate, Isopropyltri (n-aminoethyl-aminoethyl) titanate, tetra (2,2diallyloxymethyl-1-butyl) bis (di-tridecyl) phosphite titanate.
[0043]
The “organic silane compound” may be a polymer type or a low molecular type, and examples
thereof include alkoxysilanes such as monoalkoxysilane, dialkoxysilane, trialkoxysilane, and
tetraalkoxysilane. It can be mentioned.
Also, vinylsilane, epoxysilane, aminosilane, methacryloxysilane, mercaptosilane and the like can
be suitably used.
[0044]
In the case of using an alkoxysilane, by hydrolysis, it is possible to further improve the volume
resistivity (the improvement of the electrical insulation property) which is the effect of the
surface treatment.
[0045]
Examples of the aforementioned "organic zirconium compound" include alkoxy zirconium and
zirconium chelate.
[0046]
Examples of the aforementioned "organic aluminum compound" include alkoxyaluminum and
aluminum chelate.
[0047]
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Examples of the above-mentioned "organic phosphorus compound" include phosphite ester,
phosphate ester, and phosphate chelate.
[0048]
The above-mentioned "surfactant" as an affinity improver may be a polymer type or a low
molecular type, and examples thereof include nonionic surfactants, anionic surfactants, and
Cationic surfactants can be mentioned.
Among these, from the viewpoint of good thermal stability, polymeric surfactants are preferred.
[0049]
Examples of the above-mentioned "nonionic surfactant" include polyether derivatives, polyvinyl
pyrrolidone derivatives, and alcohol derivatives, and among them, from the viewpoint of good
affinity with the above "inorganic oxide particles", poly Ether derivatives are preferred.
[0050]
Examples of the above-mentioned "anionic surfactant" include polymers containing sulfonic acid
and carboxylic acid, and salts thereof.
Among them, acrylic acid derivative polymers (poly (acrylic acid) derivative) and methacrylic acid
derivative polymers (poly (methacrylic acid) derivative) are preferable as preferable examples
from the viewpoint of good affinity to the above-mentioned "polymer". Can be mentioned.
[0051]
Examples of the above-mentioned "cationic surfactant" include amine compounds, compounds
having a nitrogen-containing composite ring such as imidazoline, and halogenated salts thereof.
[0052]
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The “epoxy group-containing compound” as the “affinity improver” may be a low molecular
weight compound or a high molecular weight compound, and examples thereof include epoxy
compounds and glycidyl compounds.
Among these, a low molecular weight compound having one epoxy group is preferable in that the
affinity to the above-mentioned "polymer" is particularly good.
[0053]
As a preferable example of the above-mentioned "epoxy group-containing compound", in
particular from the point of being excellent in affinity with the above-mentioned "polymer", a
formula:
[0054]
<img class = "EMIRef" id = "403060514-00002" />
[0055]
(Wherein R represents a hydrogen atom, a methyl group, an oxygen atom or a hydrocarbon
group having 2 to 10 carbon atoms which may have a nitrogen atom, or an aromatic ring group
which may be substituted.
l represents 0 or 1, m represents 0 or 1, n represents an integer of 0 to 10.
The compound represented by these is mentioned.
[0056]
Specific examples thereof include compounds having a ketone group or an ester group such as
<img class = "EMIRef" id = "403060514-000003" />.
[0057]
The above-mentioned "affinity improvement agent" can be used in an amount within the range
where the effect of the present invention is not lost, but specifically, in terms of uniform
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dispersion and high relative dielectric constant of the obtained film, The amount thereof is
preferably in the range of 0.01 to 30 parts by mass, more preferably in the range of 0.1 to 25
parts by mass, still more preferably 1 to 20 parts by mass with respect to 100 parts by mass of
"inorganic oxide particles". Within the range of parts by mass.
[0058]
Furthermore, the organic piezoelectric film of the present invention may contain other additives
as long as the effects of the present invention are not lost.
[0059]
In the present specification, the “piezoelectric constant d 33” of the organic piezoelectric film
is a value determined according to the following measurement method.
[0060]
Piezoelectric constant and its coefficient of variation
[0061]
<Method of Determining Piezoelectric Constant d 33> Piezoelectric constant d 33 is measured
using Piezometer PM300 (a pin with a tip of 1.5 mm is attached as a sample fixing jig)
manufactured by PIEZOTEST Co., or an equivalent thereof. It is done using.
Here, the piezoelectric constant d 33 is measured at 10 points on the selected film excluding
arbitraryness, and the arithmetic average value is taken as the piezoelectric constant d 33.
In the present invention, the selection of 10 points on the film excluding the arbitraryness can be
performed, for example, by selecting 10 points at intervals of 50 mm on a straight line.
Here, arbitrary means that the coefficient of variation described later is intended to be small.
The measured value of the piezoelectric constant d 33 is a positive value or a negative value
depending on the front and back of the film to be measured, but in the present specification, the
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absolute value is described as the value of the piezoelectric constant d 33 .
[0062]
The variation coefficient of the “piezoelectric constant d 33” of the organic piezoelectric film is
the ratio of the standard deviation of the “piezoelectric constant d 33” to the arithmetic mean.
[0063]
The variation coefficient of the piezoelectric constant d 33 of the organic piezoelectric film of the
present invention is 2.0 or less.
Thereby, the organic piezoelectric film of the present invention has small in-plane variation of
piezoelectricity, and specifically, for example, it has the following advantages.
The organic piezoelectric film of the present invention, for example, when used for a touch panel
capable of detecting a touch pressure (in particular, even when used for a touch panel capable of
detecting a large area of touch pressure), malfunction does not easily occur.
In addition, the organic piezoelectric film of the present invention can realize stable sensing, for
example, when used for a pressure sensor (particularly, even when used for a large area pressure
sensor).
In addition, when the organic piezoelectric film of the present invention is used for a haptic
device, for example, operation errors and device malfunction are less likely to occur.
In addition, when the organic piezoelectric film of the present invention is used in, for example, a
vibration power generation device, a constant and stable power generation amount can be
obtained.
In addition, the organic piezoelectric film of the present invention is excellent in that high sound
quality can be obtained, for example, when used for a flat speaker (particularly, even when used
for a large area flat speaker).
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[0064]
The variation coefficient of the piezoelectric constant d 33 of the organic piezoelectric film of the
present invention is preferably smaller in this respect, and therefore, the upper limit of the
variation coefficient is preferably 1.0, more preferably 0.6, More preferably, it can be 0.4, still
more preferably 0.3, and particularly preferably 0.15.
[0065]
On the other hand, in the application or usage mode of the organic piezoelectric film of the
present invention, it may not be necessary to have a very small coefficient of variation.
In this case, a larger coefficient of variation may be advantageous in terms of manufacturing cost
and the like. Therefore, the lower limit of the variation coefficient of the piezoelectric constant d
33 of the organic piezoelectric film of the present invention can be, for example, 0.0001, 0.001,
0.01, or 0.02.
[0066]
The variation coefficient of the piezoelectric constant d 33 of the organic piezoelectric film is, for
example, in the range of 0.01 to 1.0, in the range of 0.01 to 0.6, in the range of 0.01 to 0.5, 0. It
can be in the range of 01 to 0.4, or in the range of 0.01 to 0.3.
[0067]
The preferred piezoelectric constant d 33 of the organic piezoelectric film of the present
invention may differ depending on the use or the mode of use.
The upper limit of the preferred piezoelectric constant d 33 of the organic piezoelectric film of
the present invention can be, for example, 30 pC / N, 28 pC / N, 26 pC / N, or 20 pC / N. The
lower limit of the preferred piezoelectric constant d 33 of the organic piezoelectric film of the
present invention can be, for example, 0.5 pC / N, 3 pC / N, 5 pC / N, 7 pC / N, or 9 pC / N. The
piezoelectric constant d 33 of the organic piezoelectric film is in the range of 0.5 to 30 pC / N, in
the range of 0.5 to 28 pC / N, in the range of 0.5 to 26 pC / N, 0.5 to 20 pC / N In the range of 3-
14-04-2019
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30 pC / N, in the range of 5-30 pC / N, in the range of 7-30 pC / N, or in the range of 9-30 pC /
N.
[0068]
The organic piezoelectric film according to a preferred embodiment of the present invention (the
embodiment of the item 3) has a piezoelectric constant d 33 in the range of less than 0.5 to 2.0
pC / N. The coefficient of variation of the piezoelectric constant d 33 of the organic piezoelectric
film of the embodiment is preferably 1.0 or less, more preferably 0.8 or less, and still more
preferably 0.5 or less. The organic piezoelectric film of this aspect can be suitably used, for
example, in a piezoelectric panel or a pressure sensor.
[0069]
The organic piezoelectric film according to another preferred embodiment (embodiment of the
item 4) of the present invention has a piezoelectric constant d 33 in the range of 2.0 to less than
4.0 pC / N and a coefficient of variation of 1. It is 0 or less (preferably 0.8 or less, more
preferably 0.5 or less, still more preferably 0.3 or less). The organic piezoelectric film of this
aspect can be suitably used, for example, in a piezoelectric panel or a pressure sensor.
[0070]
The organic piezoelectric film of another preferable aspect (embodiment of the above item 5) of
the present invention has a piezoelectric constant d 33 in the range of 4.0 to less than 6.0 pC / N
and a coefficient of variation of 0. It is 6 or less (preferably 0.5 or less, more preferably 0.4 or
less, still more preferably 0.3 or less). The organic piezoelectric film of this aspect can be suitably
used, for example, in a piezoelectric panel, a pressure sensor, a haptic device, a piezoelectric
vibration power generator, or a flat speaker.
[0071]
The organic piezoelectric film according to another preferred embodiment (embodiment of the
item 6) of the present invention has a piezoelectric constant d 33 in the range of 6.0 to less than
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10.0 pC / N and a coefficient of variation of 0. It is 4 or less (preferably 0.3 or less, more
preferably 0.25 or less, still more preferably 0.2 or less). The organic piezoelectric film of this
aspect can be suitably used, for example, in a piezoelectric panel, a pressure sensor, a haptic
device, a piezoelectric vibration power generator, or a flat speaker.
[0072]
The organic piezoelectric film according to another preferred embodiment (embodiment of the
item 7) of the present invention has a piezoelectric constant d 33 in the range of 10.0 to 14.0 pC
/ N and a coefficient of variation of 0. It is 3 or less (preferably, 0.25 or less, more preferably, 0.2
or less, still more preferably, 0.15 or less). The organic piezoelectric film of this aspect can be
suitably used, for example, in a piezoelectric panel, a pressure sensor, a haptic device, a
piezoelectric vibration power generator, or a flat speaker.
[0073]
The organic piezoelectric film according to another preferred embodiment (embodiment of the
item 8) of the present invention has a piezoelectric constant d 33 in the range of 14.0 to 30.0 pC
/ N and a coefficient of variation of 0.15. It is the following (preferably 0.1 or less, more
preferably 0.08 or less, still more preferably 0.07 or less). The organic piezoelectric film of this
aspect can be suitably used, for example, in a piezoelectric panel, a pressure sensor, a haptic
device, a piezoelectric vibration power generator, or a flat speaker.
[0074]
Total light transmittance
[0075]
<Method of determining total light transmittance> In the present specification, “total light
transmittance” uses a haze meter NDH-7000 SP (product name, Nippon Denshoku Kogyo) or its
equivalent based on JIS K-7361. Obtained by the light transmission test.
[0076]
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The preferable total light transmittance of the organic piezoelectric film of the present invention
may differ depending on the use or the mode of use.
In applications or use modes where high transparency is required, higher total light
transmittance is required.
On the other hand, in applications or usage modes where high total light transmittance is not
required, an organic piezoelectric film having relatively low total light transmittance may be
advantageous in terms of manufacturing cost and the like. The upper limit of the total light
transmittance of the organic piezoelectric film of the present invention can be, for example, 97%,
96%, or 94%. The lower limit of the total light transmittance of the organic piezoelectric film of
the present invention can be, for example, 70%, 80%, or 90%. The total light transmittance of the
organic piezoelectric film of the present invention can be, for example, in the range of 70 to 97%,
in the range of 80 to 96%, or in the range of 80 to 94%.
[0077]
Haze value
[0078]
<Method of Determining Haze Value> In the present specification, “total haze value” (total
haze) is based on JIS K-7136, and a haze meter NDH-7000 SP (product name, Nippon Denshoku
Kogyo) or an equivalent thereof Obtained by the haze (HAZE, turbidity) test using
In the present specification, “inner haze value” refers to the method of measuring the total
haze value by inserting water into a glass cell, inserting a film therein, and measuring the haze
value. It is obtained by In the present specification, the "outer haze value" (outer haze) is
calculated by subtracting the internal haze value from the total haze value of the film.
[0079]
The preferred total haze value of the organic piezoelectric film of the present invention may vary
depending on the use or the mode of use. A lower haze value is required in applications or use
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modes where high transparency is required. On the other hand, in applications or usage modes
where a low overall haze value is not required, an organic piezoelectric film having a relatively
high overall haze value may be advantageous in terms of manufacturing cost and the like. The
upper limit of the total haze value of the organic piezoelectric film of the present invention can
be, for example, 90%, 80%, 70%, or 60%. The lower limit of the total haze value of the organic
piezoelectric film of the present invention can be, for example, 0.3%, 0.4%, 0.5%, 5%, 20%, or
40%. The total haze value of the organic piezoelectric film of the present invention is, for
example, in the range of 0.3 to 80%, in the range of 0.4 to 70%, in the range of 0.5 to 70%, 0.5 to
60% Or within the range of 0.5 to 50%.
[0080]
The preferred internal haze value of the organic piezoelectric film of the present invention may
vary depending on the use or the mode of use. Lower internal haze values are required in
applications or use modes where high transparency is required. On the other hand, in
applications or usage modes where a low overall haze value is not required, an organic
piezoelectric film having a relatively high internal haze value may be advantageous in terms of
manufacturing cost and the like. The upper limit of the internal haze value of the organic
piezoelectric film of the present invention can be, for example, 90%, 80%, 70%, 60%, 50%, or
40%. The lower limit of the internal haze value of the organic piezoelectric film of the present
invention can be, for example, 0.01%, 0.05%, 0.1%, 0.15%, 5%, 10%, or 20%. . The internal haze
value of the organic piezoelectric film of the present invention is, for example, in the range of
0.05 to 80%, in the range of 0.1 to 70%, or in the range of 0.15 to 60%, 5 to 90% It can be in the
range, in the range of 10 to 80%, or in the range of 20 to 70%.
[0081]
The preferred external haze value of the organic piezoelectric film of the present invention may
vary depending on the use or the mode of use. Lower external haze values are required in
applications or use modes where high transparency is required. On the other hand, in
applications or usage modes where a low overall haze value is not required, an organic
piezoelectric film having a relatively high external haze value may be advantageous in terms of
manufacturing cost and the like. Since the external haze value is calculated by subtracting the
internal haze value from the total haze value of the film, examples of the external haze value of
the organic piezoelectric film of the present invention include the above-mentioned examples of
the total haze value and the above-mentioned internal It is understood from the example of haze.
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[0082]
thickness
[0083]
<Method of Determining Thickness> In the present specification, the arithmetic mean value of
each thickness measured at 10 points on a film selected excluding arbitraryness is taken as the
thickness of the film.
[0084]
The lower limit of the thickness of the organic piezoelectric film of the present invention can be,
for example, 0.1 μm, 0.5 μm, 0.8 μm, 1 μm, 3 μm, 6 μm, 9 μm, or 10 μm.
The upper limit of the thickness of the organic piezoelectric film of the present invention can be,
for example, 200 μm, 100 μm, 50 μm, 40 μm, or 30 μm.
The thickness of the organic piezoelectric film of the present invention is, for example, within the
range of 0.1 to 200 μm, within the range of 1 to 100 μm, within the range of 0.5 to 100 μm,
within the range of 0.8 to 50 μm, Within the range of 40 to 40 μm, within the range of 3 to
100 μm, within the range of 3 to 50 μm, within the range of 6 to 50 μm, within the range of 9
to 40 μm, within the range of 10 to 50 μm, or within the range of 10 to 40 μm It can be in the
range of ~30 μm. The preferred thickness can vary depending on the application of the organic
piezoelectric film of the present invention.
[0085]
The organic piezoelectric film of the present invention can be a stretched or non-stretched
piezoelectric film. The organic piezoelectric film of the present invention is preferably a nonstretched piezoelectric film. In connection with this, the organic piezoelectric film of the present
invention has high uniformity of thickness. Specifically, preferably, the organic piezoelectric film
of the present invention has a coefficient of variation of thickness of 10% or less. Here, the
thickness variation coefficient is the ratio of the standard deviation to the arithmetic mean of the
film thickness, which is the arithmetic mean value. Also related to this, the organic piezoelectric
14-04-2019
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film of the present invention has high shape uniformity and visual uniformity (i.e., in a state
where no tension other than tension due to gravity is applied). Less curvature). Moreover, in
connection with this, the organic piezoelectric film of the present invention has high uniformity
of polarizability.
[0086]
The organic piezoelectric film of the present invention is preferably a non-stretched piezoelectric
film. In connection with this, the organic piezoelectric film of the present invention has high
uniformity of thickness. Specifically, preferably, the organic piezoelectric film of the present
invention has a coefficient of variation of thickness of 10% or less. Here, here, the thickness is
measured every 5 mm (that is, at the grid points of 5 mm × 5 mm square grids) over the entire
plane of the film, and the arithmetic mean value of the thickness is measured for the organic
piezoelectric film of the present invention. Let thickness. The coefficient of variation of the
thickness of the organic piezoelectric film is the ratio of the standard deviation to the arithmetic
mean of the thickness. Also related to this, the organic piezoelectric film of the present invention
has high shape uniformity and visual uniformity (i.e., in a state where no tension other than
tension due to gravity is applied). Less curvature). Moreover, in connection with this, the organic
piezoelectric film of the present invention has high uniformity of polarizability.
[0087]
Tensile modulus
[0088]
<Method of Determining Tensile Elasticity Coefficient> In this specification, the tensile elastic
modulus is obtained by cutting out a film sample to a width of 20 mm × length 100 mm, using
an autograph (Shimadzu Corporation), 50 mm between chucks, speed 50 mm / min It is
determined by measuring based on JIS K7127 under the condition of
[0089]
The lower limit of the tensile modulus of elasticity of the organic piezoelectric film of the present
invention can be, for example, 0.4 GPa, 0.5 GPa, or 0.6%.
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The upper limit of the tensile modulus of elasticity of the organic piezoelectric film of the present
invention can be, for example, 5 GPa, 4 GPa, or 3 GPa.
The tensile elastic modulus of the organic piezoelectric film of the present invention can be, for
example, in the range of 0.5 to 10000 nm, in the range of 0.5 to 7000 nm, or in the range of 0.5
to 4000 nm.
[0090]
リタデーション
[0091]
<Method of Determining Retardation> In the present specification, in the retardation, a film
sample is cut out to a size of 2 cm × 2 cm or more, and a retardation film / optical material
inspection apparatus RETS-100 (product name, Otsuka Electronics) or its It is determined by
measurement using an equivalent.
In the present specification, as a numerical value of retardation, a value of 550 nm is adopted.
[0092]
The lower limit of the retardation of the organic piezoelectric film of the present invention is not
particularly limited, and may be, for example, 0.5 nm. The upper limit of the retardation of the
organic piezoelectric film of the present invention can be, for example, 10000 nm, 7000 nm, or
4000 nm. The retardation of the organic piezoelectric film of the present invention can be
preferably in the range of 0.5 to 10000 nm, more preferably in the range of 0.5 to 7000 nm, and
still more preferably in the range of 0.5 to 4000 nm. . The organic piezoelectric film of a
preferred embodiment of the present invention is a stretched film, and the retardation is in the
range of 200 to 10,000 nm. The organic piezoelectric film of another preferred embodiment of
the present invention is a non-oriented film, and the retardation is in the range of 0.5 to 200 nm.
[0093]
Production Method The organic piezoelectric film of the present invention may be prepared, for
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example, by a step A of preparing a non-stretched non-polarized polymer film (eg non-polarized
vinylidene fluoride polymer film) by a casting method; And B at a given time point with respect to
the step B, and a step C of heat treating the non-oriented polymer film.
[0094]
Process A (film preparation process)
[0095]
The method for producing the “non-oriented and non-polarization film” by casting method is,
for example, (1) the polymer (that is, the polymer forming the organic piezoelectric film of the
present invention) in a solvent A step of preparing a liquid composition by dissolving or
dispersing the vinylidene polymer) and the optional components (eg, inorganic oxide particles
and affinity improver) in a solvent to dissolve the liquid composition; (2) a step of casting
(coating) the liquid composition on a substrate; and (3) a step of vaporizing the solvent by
heating to form a film.
[0096]
The dissolution temperature in the preparation of the liquid composition is not particularly
limited, but raising the dissolution temperature is preferable because it can promote dissolution.
However, since the resulting film tends to be colored if the melting temperature is too high, the
melting temperature is preferably from room temperature to 80 ° C.
Further, from the viewpoint of preventing such coloration, preferred examples of the solvent
include ketone solvents (eg, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), acetone,
diethyl ketone, dipropyl ketone, cyclohexanone), and ester solvents. Solvents (eg, ethyl acetate,
methyl acetate, propyl acetate, butyl acetate, ethyl lactate), ether solvents (eg, tetrahydrofuran,
methyltetrahydrofuran, dioxane), and amide solvents (eg, dimethylformamide (DMF),
dimethylacetamide) Can be mentioned.
These solvents may be used alone or in combination of two or more. As the solvent, an amidebased solvent which is a solvent widely used for dissolving polyvinylidene fluoride (PVDF) may
be used, but the content of the amide-based solvent in the solvent is preferably 50% by weight or
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less.
[0097]
Casting (coating) of the liquid composition on a substrate is carried out by casting (coating) the
liquid composition onto a substrate using a knife coating method, a cast coating method, a roll
coating method, a gravure coating method, It may be performed based on a conventional method
such as a blade coating method, a rod coating method, an air doctor coating method, or a slot die
method. Among them, a gravure coating method or a slot die method is preferable in terms of
easy operability, small variation in film thickness to be obtained, and excellent productivity. As
the said base material, a polyethylene terephthalate (PET) film can be used, for example.
[0098]
The evaporation by heating and drying of the solvent may be carried out according to a general
method of heating and drying for film formation. The heat drying can be preferably carried out,
for example, by passing the liquid composition applied on the substrate through a drying furnace
in a roll-to-roll method. Alternatively, the film may be formed by heating and drying batchwise.
Although the said drying temperature changes with kinds of polymer which comprises the
organic piezoelectric film of this invention, when the said polymer is a vinylidene fluoride /
tetrafluoroethylene copolymer specifically, 20 degrees are preferable, for example It is in the
range of C to 200 ° C., more preferably in the range of 60 ° C. to 190 ° C., still more
preferably in the range of 80 ° C. to 190 ° C.
[0099]
The thickness of the non-polarization film prepared in step A may be set according to the
piezoelectric film to be obtained.
[0100]
Step B (Polarization Step) In step B, the non-polarization film is subjected to polarization
treatment.
[0101]
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The non-polarized copolymer film (hereinafter sometimes simply referred to as "non-polarized
film") used in step B is preferably one which is not stretched.
In addition, preferably, also in the method of manufacturing an organic piezoelectric film of the
present invention, the non-polarization film is not stretched.
The organic piezoelectric film thus obtained has high piezoelectricity even after being exposed to
high temperatures. Moreover, the organic piezoelectric film obtained in this manner has a small
variation in thickness.
[0102]
The polarization treatment of step B can be performed by a conventional method such as corona
discharge treatment.
[0103]
The polarization treatment of step B is preferably performed by corona discharge.
Either a negative corona or a positive corona may be used for the corona discharge, but it is
desirable to use a negative corona from the viewpoint of the polarization of the unpolarized resin
film.
[0104]
The corona discharge treatment is not particularly limited. For example, as described in JP-A2011-181748, applying a linear electrode to a non-polarizing film is performed; acicular to the
non-polarizing film The application can be carried out by using an electrode; or by applying a
grid electrode to a non-polarized film. The conditions of the corona discharge treatment may be
set as appropriate based on common sense in the technical field to which the present invention
belongs. When the conditions of the corona discharge treatment are too weak, the
piezoelectricity of the obtained piezoelectric film may be insufficient. On the other hand, when
the conditions of the corona discharge treatment are too strong, the obtained piezoelectric film
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may have point defects. is there. Here, in order to suppress the in-plane variation of the
piezoelectric constant d 33 of the obtained polarized film, the distance between each needle
electrode and / or linear electrode and the film is constant, that is, the electrode and the film
There is no (or very small) in-plane variation in the distance between (specifically, the difference
between the longest distance and the shortest distance is preferably within 6 mm, more
preferably 4 mm, still more preferably 3 mm Is desirable). Moreover, in order to suppress the inplane variation of the piezoelectric constant d 33 of the obtained polarized film, for example, in
the case of performing continuous application by roll-to-roll, the film is applied in such a manner
that a constant tension is applied to the film. It is desirable to make the film adhere to the roll
moderately and uniformly. For example, in the case of performing continuous application roll-toroll using a linear electrode, it varies depending on the distance between the linear electrode and
the non-polarization film, film thickness, etc. It is a DC electric field. The processing speed is, for
example, 10 to 500 cm / min. Alternatively, the polarization treatment may be performed, for
example, by sandwiching and applying a flat plate electrode from both sides of the nonpolarization film, in addition to the corona discharge. Specifically, for example, when the
application is carried out by sandwiching the flat electrode from both sides of the nonpolarization film, a DC electric field of 0 to 400 MV / m (preferably 50 to 400 MV / m) and 0.1
seconds to 60 minutes The conditions of the application time of can be adopted.
[0105]
Step C (Heat Treatment Step) Step C is performed at any time point with respect to step B. That
is, the step C can be performed before the step B, simultaneously with the step B, or after the
step B. When the step C is carried out after the step B, the heat treatment of the step C can be
carried out on the polarized film obtained in the step B or the portion which is completely
polarized in the step B. That is, while performing the polarization process of step B, the heat
treatment of step C may be performed on the portion after the polarization process. Although the
method of heat treatment is not particularly limited, for example, sandwiching the non-stretched
polymer film (hereinafter sometimes referred to simply as the film) between two metal plates and
heating the metal plate; the film Heating the metal roll in a constant temperature bath; or in the
production of the film in a roll-to-roll system, heating the metal roll and bringing the film into
contact with the heated metal roll; or the film It can be done by rolling it through a heated
furnace. Here, when the step C is performed after the step B, the polarized film may be heattreated alone, or may be laminated on another type of film or metal foil to form a laminated film
and heat-treated it. . In particular, in the case of heat treatment at high temperature, the latter
method is preferable because the polarized film is less prone to wrinkles. The temperature of the
heat treatment may vary depending on the type of the polarized film to be heat-treated, and
preferably (melting point of the heat-treated polarized film-100) to-(melting point of the heattreated polarized film + 40) Within the scope of Specifically, the temperature of the heat
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treatment is preferably 80 ° C. or more, more preferably 85 ° C. or more, still more preferably
90 ° C. or more. Moreover, the temperature of the said heat processing becomes like this.
Preferably it is 170 degrees C or less, More preferably, it is 160 degrees C or less, More
preferably, it is 140 degrees C or less. The heat treatment time is usually 10 seconds or more,
preferably 0.5 minutes or more, more preferably 1 minute or more, and further preferably 2
minutes or more. Moreover, although the upper limit of the time of the said heat processing is
not limited, Usually, the time of the said heat processing is 60 minutes or less. The conditions for
the heat treatment are preferably 90 ° C. or more and one minute or more.
[0106]
After the heat treatment, the film is cooled to a predetermined temperature. The temperature is
preferably in the range of 0 ° C. to 60 ° C. and can be room temperature. The cooling rate may
be slow cooling or rapid cooling, and rapid cooling is preferable from the viewpoint of
productivity. The quenching may be performed by means of, for example, air blowing. In the
present specification, such heat treatment of the film may be referred to as annealing treatment.
[0107]
Roll of Organic Piezoelectric Film The organic piezoelectric film of the present invention may
preferably be stored and shipped as a roll. The elastic modulus of the organic piezoelectric film of
the present invention is preferably 500 MPa or more from the viewpoint of suppressing the
generation of wrinkles in the form of such a roll. The elastic modulus can be adjusted by
selection of the material of the film or the like. The roll of the organic piezoelectric film of the
present invention may consist only of the organic piezoelectric film of the present invention, or
may be a form in which a protective film or the like is laminated on the organic piezoelectric film
of the present invention and wound. You may provide the organic piezoelectric film of this
invention wound around the said core. The roll of the organic piezoelectric film of the present
invention is preferably 50 mm or more in width and 20 m or more in length. The roll of the
organic piezoelectric film of the present invention can be prepared, for example, by winding the
organic piezoelectric film of the present invention using a unwinding roller and a winding roller.
Here, from the viewpoint of suppressing the deflection of the film, it is preferable to parallelize
the unwinding roller and the winding roller as is usually performed. Further, among the organic
piezoelectric films of the present invention, a film having a modulus of 500 MPa or more may be
used from the viewpoint of suppressing the deflection of the film. As the roller, in order to
improve the slipperiness of the film of the present invention, use is made of a highly slidable
roller, specifically a roller coated with a fluorine resin, a plated roller, or a roller coated with a
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release agent Is preferred. Here, when the thickness of the film is nonuniform, so-called roll
earing (high edge; the end is thicker than in the axial center of the roll; the film thickness is lower
at both ends than at the center If both ends are recessed compared to the central part; or if the
thickness changes in an inclined manner from one end to the other end, the end on the thin film
side is recessed etc. Uneven roll thickness occurs, which can be a source of wrinkles. Also, this
may cause deflection of the film (curvature in a state where tension other than tension due to
gravity is not applied) when the film is unwound. In general, slitting the film end which is the end
of the roll is performed in order to prevent the roll from standing out, but if the film thickness
non-uniformity extends over a wide range from the film end, the ear dropping is performed. Only
by itself, it is difficult to prevent earing and denting of the roll. Also, generally, the more the film
is wider (e.g., 100 mm or more) and the longer the film (e.g., 50 m or more), the more easily the
ear, the dent and the deflection occur.
However, since the thickness of the organic piezoelectric film of the present invention is high, the
width of the film can be increased simply by slitting the film end as it is or at the end of the roll.
Even when the length of the film is 100 mm or more and the film length is long (e.g., 50 m or
more), it is possible to obtain a roll in which the above-mentioned earing, the above-mentioned
dent and the above-mentioned deflection are suppressed. The slit-removed ear (film end) can be
collected and recycled as a raw material of the organic piezoelectric film of the present invention.
The roll of the organic piezoelectric film of the present invention has high uniformity of
thickness, and preferably, the ratio of the thickness of the thicker end to the thickness of the
axial center of the roll is 70 to 130%. It is in the range. As a result, the roll of the organic
piezoelectric film of the present invention suppresses the deflection of the film unwound
therefrom.
[0108]
It is preferable that surface roughness Ra of the roller used for manufacture of the organic
piezoelectric film of this invention and its roll is 1 micrometer or less. In the present
specification, “surface roughness Ra” is “arithmetic average height” defined in JIS B0601:
2001. Moreover, it is preferable that the material of the surface of the roller used for
manufacture of the organic piezoelectric film of this invention and its roll is a
polytetrafluoroethylene (PTFE), chromium plating, or stainless steel (SUS) at least. By these
things, the wrinkles of a film can be controlled.
[0109]
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Application Since the organic piezoelectric film of the present invention has high piezoelectricity
even after being exposed to high temperature, it can be suitably used for various applications
where high piezoelectricity is required and which may be exposed to high temperature . In
addition, since the organic piezoelectric film of the present invention has flexibility, it can be
suitably used in various applications.
[0110]
Piezoelectric Panel The organic piezoelectric film of the present invention (preferably, the
organic piezoelectric film of the aspect described in any one of items 1 to 13) can be used for a
piezoelectric panel (for example, a touch panel capable of detecting a touch pressure). The touch
panel having the organic piezoelectric film of the present invention can detect both the touch
position and the touch pressure, and the touch pressure detection performance is unlikely to
deteriorate even after being exposed to high temperature. The organic piezoelectric film of the
present invention can be used for a touch panel of any type such as a resistive film type and a
capacitance type. The organic piezoelectric film of the present invention does not necessarily
have to be used for detection of both the touch position and the touch pressure when used in a
touch panel, and the organic piezoelectric film of the present invention has a touch position or a
touch pressure of It may be used for either detection. The piezoelectric panel having the organic
piezoelectric film of the present invention preferably has the first electrode, the organic
piezoelectric film of the present invention, and the second electrode in this order. The first
electrode is disposed directly or indirectly on one major surface of the organic piezoelectric film
of the present invention, and the second electrode is disposed directly or indirectly on the other
major surface of the organic piezoelectric film of the present invention Be placed. Here, the
number of organic piezoelectric films of the piezoelectric panel can be one or more. Here, in
order to remove pyroelectric noise of the piezoelectric panel, two organic piezoelectric films have
a bimorph structure (eg, a bimorph structure as described in FIG. 18 of WO 2015/053343). You
may form. At this time, the two organic piezoelectric films may be pasted together with a
transparent adhesive or a transparent adhesive. Here, the thickness of the transparent pressuresensitive adhesive or the layer of the transparent adhesive is preferably thicker if its tensile
modulus is larger than that of the organic piezoelectric film, and thinner if it is smaller.
Moreover, as for the thickness of the two organic piezoelectric films, it is preferable that the film
on the side to which pressure is applied be thicker. Examples of the electrode include an ITO
(indium tin oxide) electrode, a tin oxide electrode, metal nanowires, metal nanoparticles, and an
organic conductive resin.
[0111]
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Pressure Sensor The organic piezoelectric film of the present invention (preferably, the organic
piezoelectric film of the aspect described in any one of the items 1 to 12 and 14) can be used for
a pressure sensor. The pressure sensor having the organic piezoelectric film of the present
invention preferably has the first electrode, the organic piezoelectric film of the present
invention, and the second electrode) in this order. The first electrode is disposed directly or
indirectly on one major surface of the organic piezoelectric film of the present invention, and the
second electrode is disposed directly or indirectly on the other major surface of the organic
piezoelectric film of the present invention Be placed. Examples of the electrode include an ITO
(indium tin oxide) electrode, a tin oxide electrode, metal nanowires, metal nanoparticles, and an
organic conductive resin.
[0112]
Haptic Device The organic piezoelectric film of the present invention (preferably, the organic
piezoelectric film of the aspect according to any one of items 1, 2, 5 to 12, and 14) can be
suitably used for a haptic device. The haptic device having the organic piezoelectric film of the
present invention preferably has the first electrode, the organic piezoelectric film of the present
invention, and the second electrode in this order. The first electrode is disposed directly or
indirectly on one major surface of the organic piezoelectric film of the present invention, and the
second electrode is disposed directly or indirectly on the other major surface of the organic
piezoelectric film of the present invention Be placed. In the haptic device, the organic
piezoelectric film of the present invention can convert the electrical energy received through the
first electrode and the second electrode into mechanical energy. As a result, the organic
piezoelectric film of the present invention is deformed, vibrates, and can provide tactile feedback
to the user.
[0113]
Piezoelectric Vibration Power Generation Device The organic piezoelectric film of the present
invention (preferably, the organic piezoelectric film of the aspect described in any one of the
items 1, 2, 5 to 12, and 14) is suitably used for a piezoelectric vibration power generation device
it can. The piezoelectric vibration power generation device having the organic piezoelectric film
of the present invention preferably has the first electrode, the organic piezoelectric film of the
present invention, and the second electrode in this order. The first electrode is disposed directly
or indirectly on one major surface of the organic piezoelectric film of the present invention, and
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the second electrode is disposed directly or indirectly on the other major surface of the organic
piezoelectric film of the present invention Be placed. The organic piezoelectric film of the present
invention can convert mechanical energy of vibration received by the piezoelectric vibration
power generator into electrical energy. The electrical energy is sent to a secondary battery or the
like through the first electrode and the second electrode.
[0114]
Flat Speaker The organic piezoelectric film of the present invention can be suitably used for a flat
speaker. A planar speaker having the organic piezoelectric film of the present invention
preferably has, in order, the first electrode, the organic piezoelectric film of the present invention,
and the second electrode. In the flat speaker, the organic piezoelectric film of the present
invention can convert electrical energy received through the first electrode and the second
electrode into mechanical energy. Thereby, the organic piezoelectric film of the present invention
is deformed, vibrates, and can generate a sound.
[0115]
The touch panel having the organic piezoelectric film of the present invention can be used for an
input device (that is, an input device having the organic piezoelectric film of the present
invention). The input device having the touch panel is capable of input based on a touch position,
a touch pressure, or both. The input device having the touch panel can have a position detection
unit and a pressure detection unit.
[0116]
The input device can be used for an electronic device (for example, a mobile phone (for example,
a smartphone), a personal digital assistant (PDA), a tablet PC, an ATM, an automatic ticket
vending machine, and a car navigation system). The electronic device having the input device can
operate and operate based on touch position, touch pressure, or both.
[0117]
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Bimorph-Type Piezoelectric Film When the organic piezoelectric film of the present invention is
used for a pressure sensor or a haptic device, the organic piezoelectric film of the present
invention has a so-called bimorph structure in which two sheets of organic piezoelectric film are
bonded to each other It may be That is, the present invention also provides the bimorph type
piezoelectric film. When using such a bimorph-type piezoelectric film as a pressure sensor, in
particular, from the viewpoint of removing pyroelectric noise, the bimorph-type piezoelectric film
is such that the polarization directions of the two organic piezoelectric films are opposite to each
other. It is preferable to have a bonded bimorph structure. As a result, the surface on which
electric charges of the same polarity are generated due to temperature rise is disposed on the
outside, so that part or all of the pyroelectric signal (pyroelectric noise) generated from each
pyroelectric film is canceled be able to. The bimorph-type piezoelectric film can usually have, for
example, a rectangular (eg, rectangular, square) shape or a circular (eg, elliptical, perfect circular)
shape in plan view. Detection electrodes can be provided on both sides of the bimorph-type
piezoelectric film (piezoelectric element) (that is, the two organic piezoelectric films of the
present invention). The two organic piezoelectric films of the present invention may be bonded to
each other with an adhesive sheet or an adhesive layer, may be in direct contact with each other,
or may be heat-fused to each other, or It may be thermocompression-bonded to each other. The
pressure-sensitive adhesive sheet is not particularly limited as long as two sheets of the organic
piezoelectric film of the present invention can be attached to each other, and can be composed of
one or more layers. That is, when the said adhesive sheet consists of one layer, the said adhesive
sheet consists of an adhesive layer, and when the said adhesive sheet consists of two or more
layers, the both outer layers are an adhesive layer. When the said adhesive sheet consists of
three or more layers, the said adhesive sheet may have a base material layer as an inner layer.
The base material layer in the pressure-sensitive adhesive sheet may be a transparent film, and
preferably, for example, a film of polyimide, polyethylene terephthalate, polybutylene
terephthalate, polycarbonate, polyparaphenylene sulfide, or polyamide imide. The pressuresensitive adhesive layer in the pressure-sensitive adhesive sheet can be, for example, a layer
containing an acrylic pressure-sensitive adhesive as a pressure-sensitive adhesive. The adhesive
forming the adhesive layer may be, for example, an acrylic adhesive.
[0118]
Hereinafter, the present invention will be described in more detail by way of examples, but the
present invention is not limited thereto.
[0119]
The following electrodes were used in the following Examples and Comparative Examples.
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<Used electrodes> (1) One row of needle for electrode (needle-like electrode) (R = 0.06 mm; made
by Morita Needles Co.) at intervals of 10 mm on the center line of a brass rod of 20 mm width
(10 mm thickness, 500 mm length) Similar to the needle-like electrode rods (2) and (1) arranged
in the above, the needle-like electrode rod (3) diameter in which the electrode needles (R = 0.06
mm; manufactured by Morita Needles Co., Ltd.) 0.1 mm gold-plated tungsten linear electrode
(500 mm long)
[0120]
In Examples and Comparative Examples described later, the total light transmittance, the total
haze value, and the piezoelectric constant d33 were measured by the following methods. <Total
Light Transmittance> Using a haze meter NDH-7000SP (product name, Nippon Denshoku
Kogyo), the measurement was performed according to the method described in JIS K-7361. <All
Haze Value> A haze meter NDH-7000SP (product name, Nippon Denshoku Kogyo) was used, and
measurement was performed based on the method described in JIS K-7136. <Internal Haze
Value> Water was introduced into a quartz cell, a film was inserted therein, and measurement
was made according to JIS K-7136 using NDH-7000SP (product name, Nippon Denshoku Kogyo).
<Measurement of Piezoelectric Constant d33> The measurement of the piezoelectric constant d
33 was performed using a piezometer system PM300 manufactured by PIEZOTEST. In the
measurement, the sample was clipped at 1 N, and the charge generated when a force of 0.25 N
and 110 Hz was applied was read. <Tensile elastic modulus> The tensile elastic modulus is based
on JIS K7127 under the conditions of 50 mm distance between chucks and 50 mm / min speed
using a autograph (Shimadzu Corporation) by cutting out a film sample 20 mm wide × 100 mm
long. It was determined by measuring. <Retardation> The retardation is determined by measuring
a film sample of 2 cm × 2 cm or more and using a retardation film / optical material inspection
device RETS-100 (product name, Otsuka Electronics). In the present specification, as a numerical
value of retardation, a value of 550 nm is adopted.
[0121]
Production Example 1 Production of Non-Polarized Film A vinylidene fluoride /
tetrafluoroethylene copolymer film (molar ratio 80: 20) having a thickness of 40 μm was
produced by the following production method. A solution of vinylidene fluoridetetrafluoroethylene copolymer (molar ratio 80:20) in dimethyl acetamide (DMAc) solution or
methyl ethyl ketone (MEK) solution is cast on a PET (polyethylene terephthalate) substrate, and a
solvent at 180 ° C. Were evaporated to form a film of 40 μm in thickness.
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[0122]
Example 1 In a clean room of ISO class 7 (humidity 60%), as outlined in FIG. 1, on a SUS ground
electrode which is a grounded roller 1 (diameter 200 mm, width 800 mm), A vinylidene fluoride
/ tetrafluoroethylene copolymer film 2 having a width of 550 mm, a length of 200 m, and each
film thickness (20 to 40 μm) shown in Table 1 so as to move along the roller 1 at a holding
angle of 200 °. (Hereinafter, the film 2 may be simply referred to. ) Was installed. As the first
electrode E1, the needle electrode is arranged such that the arrangement of the needle electrodes
is perpendicular to the surface of the roller 1 (that is, the radial direction of the roller 1), and
from the film 2 The tip of the electrode E1) was placed at a position 10 mm above the air. The
first high voltage power supply V1 is connected to the first electrode E1. Furthermore, tungsten
plated with gold having a diameter of 0.1 mm as a second electrode E2 at a position 100 mm
apart and 150 mm apart from the needle electrode (first electrode E1) in length of the film 2 One
linear electrode (550 mm long) made of aluminum was placed at a position spaced 20 mm above
the film 2 in the sky. The second high voltage power supply V2 is connected to each second
electrode E2. After applying a voltage of -10 kV to the needle electrode (first electrode E1) and a
voltage of -10 to -15 kV to the linear electrode (second electrode E2), the film 2 is applied at a
speed of 96 cm / min. A metal roll is moved in the direction of the arrow in FIG. 3 to pass under
the corona discharge generated from the tip of the needle electrode (first electrode) and the
subsequent linear electrode (second electrode), and further, to the earthed metal roll. The film 2
was discharged by bringing the film 2 into contact with 3 (diameter 70 mm). Thereafter, both
ends of the film 2 were respectively removed by 0.5 cm width using a slitter, and the obtained
polarized film was wound around a cylindrical core having a diameter of 6 inches while
sandwiching the PET film. Here, the distance between the needle electrode (first electrode E1)
and the film 2 and the distance between the linear electrode (second electrode E2) and the film 2
are both constant (the longest distance and the shortest distance between the electrode and the
film) Eight samples were manufactured (sample numbers 1 to 8) by adjusting the distance
difference to be 0 mm. In addition to this, unlike the following two samples (sample numbers 9
and 10) and the above-mentioned sample numbers 1 to 8, the distance between the needle
electrode (first electrode E1) and the film 2 is constant. Although it was prepared, on the other
hand, it was omitted that the distance between the linear electrode (the second electrode E2) and
the film 2 was fixed so that the linear electrode was inclined and fixed, and the film 2 was moved
in the traveling direction On the other hand, one sample (film thickness 40 μm) was
manufactured in a state in which the right end was fixed at a position 25 mm above the film 2
from the film 2 and the left end was at a position 15 mm above the air.
Unlike the sample numbers 1 to 8 described above, the distance between the linear electrode
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(second electrode E2) and the film 2 was adjusted to be constant, while the needle electrode (first
electrode E1) and the film 2 were prepared. The linear electrode is inclined and fixed so that the
right end is 20 mm above the film 2 with respect to the direction of travel of the film, and the left
end is 10 mm above the sky. One sample (film thickness 20 μm) was manufactured (sample No.
10) while fixed at a distant position.
[0123]
Test Example 1 For measurement of piezoelectricity, a d33 meter PM300 manufactured by Piezo
Test (a pin with a tip of 1.5 mmφ attached as a sample fixing jig) was used. In this meter, under
the conditions of Rng / Mode: VLO / d33, Frequency: 110 Hz, and Dyn Force: 0.25 N, place 102
g of weight on the detection part, and the St. F of the meter becomes 1.0 N. After confirming that,
measurement was performed according to the following procedure of the tip on the sample fixing
jig. (1)50The film was cut to a size of mm [flow direction] / 500 mm [width direction] (2) The
film was placed on a flat and clean table so that no folds or wrinkles were formed in the
piezoelectric film. (3)An oil-based pen was used to mark 10 locations at intervals of 50 mm in the
width direction. (4)Set the film on the detection part so that wrinkles and creases do not occur,
turn the trigger clockwise, and lower the force head until St. F: 1.0 N, and after each mark for 30
seconds, d33 The value of was read. Table 1 shows the measurement results.
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