U.S. patent application number 17/653000 was filed with the patent office on 2022-08-25 for spun yarn, and yarn and cloth including spun yarn.
The applicant listed for this patent is Murata Manufacturing Co., Ltd.. Invention is credited to Tomoharu KIDOU, Eiji TAGUCHI, Kenichiro TAKUMI, Masayuki TSUJI.
Application Number | 20220267934 17/653000 |
Document ID | / |
Family ID | 1000006380816 |
Filed Date | 2022-08-25 |
United States Patent
Application |
20220267934 |
Kind Code |
A1 |
TAKUMI; Kenichiro ; et
al. |
August 25, 2022 |
SPUN YARN, AND YARN AND CLOTH INCLUDING SPUN YARN
Abstract
A spun yarn that includes at least a first short fiber that is a
piezoelectric fiber that generates a potential by applied external
energy, and that has a length of 800 mm or less. The spun yarn
preferably includes a plurality of short fibers that are twisted
together with each other.
Inventors: |
TAKUMI; Kenichiro;
(Nagaokakyo-shi, JP) ; TSUJI; Masayuki;
(Nagaokakyo-shi, JP) ; TAGUCHI; Eiji;
(Nagaokakyo-shi, JP) ; KIDOU; Tomoharu; (Osaka,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Murata Manufacturing Co., Ltd. |
Nagaokakyo-shi |
|
JP |
|
|
Family ID: |
1000006380816 |
Appl. No.: |
17/653000 |
Filed: |
March 1, 2022 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/JP20/46842 |
Dec 16, 2020 |
|
|
|
17653000 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
D10B 2401/16 20130101;
D02G 3/04 20130101; D10B 2331/041 20130101; D10B 2401/06 20130101;
D02G 3/26 20130101 |
International
Class: |
D02G 3/26 20060101
D02G003/26; D02G 3/04 20060101 D02G003/04 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 20, 2019 |
JP |
2019-230177 |
Claims
1. A spun yarn, comprising at least a first short fiber that
generates a potential by external energy and has a length of 800 mm
or less.
2. The spun yarn according to claim 1, wherein the length of the
first short fiber is 10 mm to 800 mm.
3. The spun yarn according to claim 1, wherein a fineness of the
first short fiber is 0.3 dtex to 10 dtex.
4. The spun yarn according to claim 1, further comprising: a second
short fiber; and a third short fiber, wherein a first end side in a
longitudinal direction of the first short fiber is restrained by
the second short fiber, and a second end side in the longitudinal
direction of the first short fiber is restrained by the third short
fiber.
5. The spun yarn according to claim 4, wherein a coefficient of
static friction of the second short fiber or the third short fiber
is higher than that of the first short fiber.
6. The spun yarn according to claim 4, wherein the first short
fiber, the second short fiber, and the third short fiber have a
crimped portion, and the first short fiber is restrained by the
crimped portion.
7. The spun yarn according to claim 1, wherein the first short
fiber is inclined relative to an axial direction of the spun
yarn.
8. The spun yarn according to claim 7, wherein an angle of the
first short fiber relative to an axial direction of the spun yarn
ranges from 0 degrees to 80 degrees.
9. The spun yarn according to claim 8, wherein the angle of the
first short fiber relative to the axial direction of the spun yarn
is 20 degrees to 50 degrees.
10. The spun yarn according to claim 4, wherein a fineness of the
first short fiber, the second short fiber, and the third short
fiber is 0.3 dtex to 10 dtex.
11. The spun yarn according to claim 4, wherein lengths of the
first short fiber, the second short fiber, and the third short
fiber are 10 mm to 800 mm.
12. The spun yarn according to claim 4, wherein the first short
fiber, the second short fiber, and the third short fiber have a
fiber count of one to 500.
13. The spun yarn according to claim 4, wherein the first short
fiber, the second short fiber, and the third short fiber have
different lengths.
14. The spun yarn according to claim 4, wherein the second short
fiber and the third short fiber are fibers having no
piezoelectricity.
15. The spun yarn according to claim 14, wherein the second short
fiber and the third short fiber comprise a material having a higher
hydrophilicity as compared with that of the first short fiber.
16. The spun yarn according to claim 1, wherein the first short
fiber is a piezoelectric fiber and comprises a chiral polymer.
17. The spun yarn according to claim 16, wherein the chiral polymer
is polylactic acid.
18. The spun yarn according to claim 4, wherein at least one of the
first short fiber, the second short fiber, and the third short
fiber has a groove or a protrusion extending in a longitudinal
direction of the first short fiber, the second short fiber, and the
third short fiber.
19. A yarn, comprising: a plurality of the spun yarns according to
claim 1, wherein the plurality of the spun yarns include a
right-twisted yarn and a left-twisted yarn.
20. A cloth, comprising: a spun yarn according to claim 1.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation of International
application No. PCT/JP2020/046842, filed Dec. 16, 2020, which
claims priority to Japanese Patent Application No. 2019-230177,
filed Dec. 20, 2019, the entire contents of each of which are
incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a spun yarn that generates
an electric charge, and a yarn and a cloth including the spun
yarn.
BACKGROUND OF THE INVENTION
[0003] Patent Document 1 discloses a yarn having antibacterial
properties. The yarn disclosed in Patent Document 1 includes a
charge generating fiber that generates a charge by external energy.
The yarn disclosed in Patent Document 1 includes a plurality of
charge generating fibers having different polarities of generated
charges, and thus exhibits an antibacterial effect between the
plurality of charge generating fibers.
[0004] Patent Document 1: Japanese Patent Application Laid-Open No.
2018-090950
SUMMARY OF THE INVENTION
[0005] When only the long fibers are strongly twisted, voids
between the long fibers become small. When the void between the
long fibers becomes small, the electric field hardly leaks to the
outside of the yarn, and therefore the antibacterial effect is
reduced.
[0006] Therefore, an object of the present invention is to provide
a spun yarn that efficiently exhibits an antibacterial effect, and
a yarn and a cloth including the spun yarn.
[0007] The spun yarn of the present invention includes at least a
first short fiber that is a piezoelectric fiber that generates a
potential by applied external energy, and has a length of 800 mm or
less. Preferably, the spun yarn includes a plurality of short
fibers that are twisted together with each other.
[0008] In the spun yarn according to the present invention, the
plurality of short fibers are complicatedly entangled with each
other. When a plurality of short fibers are twisted with each
other, each of the short fibers is whirled along various
directions. That is, each of the short fibers is along a random
direction relative to the axial direction of the spun yarn.
[0009] When the spun yarn is extended in the axial direction,
external forces such as tension, twist, and bending in various
directions are applied to each short fiber in the spun yarn in the
axial direction of each short fiber. Each short fiber generates
charges of various magnitudes and polarities depending on the
magnitude and direction of the external force applied. Thus, the
spun yarn can generate various local electric fields between the
respective short fibers. Therefore, the spun yarn according to the
present invention can efficiently exhibit an antibacterial
effect.
[0010] The present invention can efficiently exhibit an
antibacterial effect.
BRIEF EXPLANATION OF THE DRAWINGS
[0011] FIG. 1(A) is a view illustrating a configuration of a spun
yarn according to a first embodiment, and FIG. 1(B) is a sectional
view taken along line I-I of FIG. 1(A).
[0012] FIG. 2(A) and FIG. 2(B) are views showing a relationship
among a uniaxial extending direction, an electric field direction
in a polylactic acid film, and deformation of the polylactic acid
film.
[0013] FIG. 3 illustrates shear stress generated in each
piezoelectric fiber when tension is applied to a spun yarn.
[0014] FIG. 4 is a sectional view schematically showing a part of a
spun yarn for explaining an antibacterial mechanism in the spun
yarn.
[0015] FIG. 5(A) is a view showing a configuration of a spun yarn
according to a second embodiment, and FIG. 5(B) is a sectional view
taken along line II-II of FIG. 5(A).
[0016] FIG. 6 is a view showing a configuration of a spun yarn
according to a third embodiment.
[0017] FIG. 7(A) is a part of an exploded view showing a
configuration of an antibacterial yarn, and FIG. 7(B) is a
sectional view of a short fiber 111.
[0018] FIG. 8 is a view showing a configuration of an antibacterial
cloth.
DETAILED DESCRIPTION OF THE INVENTION
[0019] FIG. 1(A) is a view showing a configuration of a spun yarn
10 according to the first embodiment, and FIG. 1(B) is a sectional
view taken along line I-I of FIG. 1(A). In FIGS. 1(A) and 1(B),
sections of seven yarns are shown as an example in a section taken
along line I-I, the number of yarns constituting the spun yarn 10
is not limited thereto, and is actually appropriately set in view
of the application and the like. In addition, FIG. 1(B) shows only
a section cut along line I-I.
[0020] The spun yarn 10 includes a plurality of short fibers 11.
The spun yarn 10 is formed by twisting a plurality of short fibers
11 with each other. The short fiber 11 is an example of a
piezoelectric fiber that generates a charge by external energy, for
example, expansion and contraction.
[0021] The short fiber 11 is composed of a functional polymer, for
example, a piezoelectric polymer. Examples of the piezoelectric
polymer include PVDF or polylactic acid (PLA). In addition,
polylactic acid (PLA) is a piezoelectric polymer having no
pyroelectricity. Polylactic acid is uniaxially extended to generate
piezoelectricity. Examples of the polylactic acid include PLLA
obtained by polymerizing an L-form monomer and PDLA obtained by
polymerizing a D-form monomer. The short fiber 11 may further
include a component other than the functional polymer as long as it
does not inhibit the function of the functional polymer.
[0022] Polylactic acid is a chiral polymer, and has a main chain
having a helical structure. Polylactic acid is uniaxially extended
to orient molecules thereof and to exhibit piezoelectricity. When
heat treatment is further performed to increase the crystallinity,
the piezoelectric constant increases. When the thickness direction
is defined as a first axis, an extending direction 900 is defined
as a third axis, and a direction orthogonal to both the first axis
and the third axis is defined as a second axis, the short fiber 11
composed of uniaxially extended polylactic acid has tensor
components of d.sub.14 and d.sub.25 as piezoelectric strain
constants. Therefore, polylactic acid generates charges most
efficiently when strain occurs in a direction of 45 degrees to the
uniaxially extended direction.
[0023] FIGS. 2(A) and 2(B) are views showing a relationship among a
uniaxial extending direction, an electric field direction in a
polylactic acid film 200, and deformation of the polylactic acid
film 200. FIGS. 2(A) and 2(B) show model cases in which the short
fiber 11 is assumed to have a film shape. As shown in FIG. 2(A),
when the polylactic acid film 200 contracts in the direction of the
first diagonal line 910A and extends in the direction of the second
diagonal line 910B orthogonal to the first diagonal line 910A, an
electric field is generated in a direction from the back side to
the front side of the paper surface. That is, in the polylactic
acid film 200, a negative charge is generated on the front side of
the paper surface. As shown in FIG. 2(B), when the polylactic acid
film 200 extends in the direction of the first diagonal line 910A
and contracts in the direction of the second diagonal line 910B,
charges are generated; however, the polarities are reversed, and an
electric field is generated in a direction from the front side to
the back side of the paper surface. That is, in the polylactic acid
film 200, a positive charge is generated on the front side of the
paper surface.
[0024] Polylactic acid has piezoelectricity due to molecular
orientation processing by extending, and thus does not need to be
subjected to poling processing unlike other piezoelectric polymers
such as PVDF or piezoelectric ceramics. The piezoelectric constant
of uniaxially extended polylactic acid is about 5 to 30 pC/N, and
is a significantly high piezoelectric constant among polymers.
Furthermore, the piezoelectric constant of polylactic acid does not
vary with time and is extremely stable.
[0025] The short fiber 11 is a fiber having a circular section. The
short fiber 11 is produced by, for example, a method of extruding
and molding a piezoelectric polymer to form a fiber, a method of
melt-spinning a piezoelectric polymer to form a fiber (examples
thereof include a spinning/extending method in which a spinning
step and a extending step are separately performed, a straight
extending method in which a spinning step and a extending step are
connected, a POY-DTY method in which a false twisting step can also
be performed at the same time, and an ultrahigh-speed spinning
method in which speed is increased), a method of dry or wet
spinning a piezoelectric polymer to form a fiber (examples thereof
include a phase separation method or a dry-wet spinning method in
which a polymer as a raw material is dissolved in a solvent and
extruded from a nozzle to form a fiber, a gel spinning method in
which a fiber is uniformly formed into a gel while including a
solvent, and a liquid crystal spinning method in which a fiber is
formed by using a liquid crystal solution or a melt), or a method
of electrostatic spinning a piezoelectric polymer to form a fiber.
The sectional shape of the short fiber 11 is not limited to a
circular shape.
[0026] A string-shaped object such as a fiber has the smallest
sectional area when cut perpendicularly to the axial direction, and
the increased sectional area as the cut surface approaches parallel
to the axial direction. As shown in FIG. 1(B), the sectional area
of each of the short fibers 11 varies in a section perpendicular to
the axial direction 101 of the spun yarn 10. This is because each
of the short fibers 11 forms a random angle to the axial direction
101 of the spun yarn 10.
[0027] The short fiber 11 is preferably 800 mm or less, more
preferably 500 mm or less, or 300 mm or less, and still more
preferably 100 mm or less, and preferably 10 mm or more in length.
Thus, as described in detail later, the short fiber 11 is easily
exposed to the outside from the side surface of the spun yarn
10.
[0028] The fineness of the short fiber 11 is preferably 0.3 dtex to
10 dtex.
[0029] The sectional shape of the short fiber 11 is not
particularly limited, and may be, for example, any of a round
section, a heteromorphic section, a hollow, a side-by-side, and a
plurality of layers of two or more layers, or may be a combination
thereof.
[0030] The spun yarn 10 is a yarn obtained by twisting a plurality
of such short fibers 11 of PLLA. The spun yarn 10 is a rightward
whirled yarn obtained by whirling the short fibers 11 rightward
(hereinafter, referred to as an S yarn). The spun yarn 10 may be a
leftward whirled yarn obtained by whirling leftward the short
fibers 11 (hereinafter, referred to as a Z yarn).
[0031] The short fiber 11 is short, and therefore when the
plurality of short fibers 11 are twisted, the short fibers are
easily whirled along a random direction. That is, as shown in FIG.
1(A), the axial direction of each short fiber 11 forms a random
angle to the axial direction 101 of the spun yarn 10. The spun yarn
10, that is, the plurality of short fibers 11 includes, for
example, short fiber 111, short fiber 112, and short fiber 113. The
short fiber 111 is an example of the first short fiber of the
present invention, the short fiber 112 is an example of the second
short fiber of the present invention, and the short fiber 113 is an
example of the third short fiber of the present invention.
[0032] The short fiber 111 is inclined leftward at 0 degrees to 80
degrees, preferably 20 degrees to 50 degrees to the axial direction
101 of the spun yarn 10; the short fiber 112 is inclined leftward
at 0 degrees to 80 degrees, preferably 20 degrees to 50 degrees to
the axial direction 101 of the spun yarn 10; and the short fiber
113 is inclined leftward at 0 degrees to 80 degrees, preferably 20
degrees to 50 degrees to the axial direction 101 of the spun yarn
10. The angles of the short fiber 111, the short fiber 112, and the
short fiber 113 to the axial direction 101 of the spun yarn 10 may
be different from each other.
[0033] The short fiber 111 shown in FIG. 1(A) is a fiber aligned in
a certain direction in a carding step among the plurality of short
fibers 11. Therefore, the spun yarn 10 includes most of the short
fibers 111. The short fiber 111 may have different lengths in the
range of 30 mm to 70 mm by bias cutting.
[0034] The short fibers 111, 112, and 113 each have a crimped
portion 62. FIG. 1(A) shows the crimped portion 62 of the short
fiber 111 as a representative. The short fiber 111 are restrained
by the crimped portion 62. For example, the first end 71 side in
the longitudinal direction of the short fiber 111 is restrained by
the short fiber 112, and the second end 72 side in the longitudinal
direction of the short fiber 111 is restrained by the short fiber
113. The short fiber 111 can maintain a bundled state without being
fibrillated by restraining the first end 71 to the short fiber 112
and the second end 72 to the short fiber 113. Thus, the user can
efficiently transmit stress to a piezoelectric fiber.
[0035] The spun yarn 10 is produced by, for example, a method such
as ring, compact, silo ring, silo compact, air fine spinning, air
spinning, mule, or flyer, and the production method is not
limited.
[0036] Each of the short fiber 111, the short fiber 112, and the
short fiber 113 preferably has a fiber count of 1 to 500.
[0037] FIG. 3 illustrates shear stress generated in each short
fiber 11 when tension is applied in the axial direction 101 of the
spun yarn 10.
[0038] As illustrated in FIG. 3, when an external force (tension)
is applied in the axial direction 101 of the spun yarn 10, the
short fiber 111 is in the state illustrated in FIG. 2(A), and
generates a negative charge on the surface and a positive charge on
the inner side. In addition, the short fiber 112 or the short fiber
113 is in the state shown in FIG. 2(A), and generates a negative
charge on the surface and a positive charge on the inner side. When
the axial direction of the short fiber 112 or the short fiber 113
is along a direction of 90 degrees to the axial direction of the
short fiber 111, the short fiber 112 or the short fiber 113 is in
the state shown in FIG. 2(B), and generates a positive charge on
the surface and a negative charge on the inner side.
[0039] Thus, when an external force (tension) is applied to the
spun yarn 10, the short fiber 111, the short fiber 112, and the
short fiber 113 generate charges of different magnitudes on the
surface. That is, the orientation of each short fiber 11 is random,
and therefore each short fiber 11 generates charges of various
magnitudes and polarities. For example, when the short fiber 112 is
along a direction of 90 degrees to the axial direction of the short
fiber 111, the first surface of the short fiber 111 faces the
second surface of the short fiber 112 across a void 41. Therefore,
a strong electric field is locally generated in a narrow region
between the short fibers 11 in the spun yarn 10. In addition, when
the force of extending the spun yarn 10 in the axial direction 101
is small, charges of various magnitudes and polarities are
generated in the plurality of the short fibers 11, and therefore an
electric field can be generated.
[0040] In the spun yarn 10, each of the plurality of short fibers
11 is whirled along a random direction. When the plurality of short
fibers 11 are strongly twisted, the void 41 is easily generated
between the plurality of short fibers 11. In addition, each short
fiber 11 generates charges of various magnitudes and polarities,
and therefore electric fields of various magnitudes are generated
in the void 41 between the short fibers 11. As described later,
this improves the antibacterial effect against the bacteria trapped
in the void 41.
[0041] FIG. 4 is a sectional view schematically showing a part of
the spun yarn 10 for explaining an antibacterial mechanism in the
spun yarn 10. As shown in FIG. 4, the spun yarn 10 can absorb
moisture 40 into a void 41 formed between the plurality of short
fibers 11. Fine particles 42 such as bacteria absorbed in the spun
yarn 10 together with the moisture 40 are easily held inside the
spun yarn 10. In addition, when the void 41 inside the spun yarn 10
becomes larger, the amount of the moisture 40 that can be absorbed
more increases, and thus the fine particles 42 held inside the spun
yarn 10 also becomes larger. Thus, the spun yarn 10 is excellent in
the performance of collecting the fine particles 42.
[0042] The spun yarn 10 collects the fine particles 42, the
moisture 40 in the spun yarn 10 evaporates, and then the fine
particles 42 remain in the void 41 of the spun yarn 10. When the
spun yarn 10 is extended in the axial direction 101, the spun yarn
10 locally generates an electric field between the plurality of the
short fibers 11. The fine particles 42 are collected in the void
41, that is, between the plurality of the short fibers 11, and
therefore the fine particles 42 in the spun yarn 10 are exposed to
the local and maximum electric field. Therefore, the spun yarn 10
can efficiently exhibit an antibacterial effect against bacteria
and the like by the generated electric field.
[0043] In addition, the spun yarn 10 has many voids 41 between the
plurality of the short fibers 11, and therefore the electric field
easily leaks to the outside of the spun yarn 10. When the spun yarn
10 comes close to an object having a predetermined potential
(including a ground potential) such as a human body, an electric
field is generated between the spun yarn 10 and the object. In this
manner, the spun yarn 10 exhibits an antibacterial effect with
other objects having a predetermined potential.
[0044] Conventionally, it has been known that the growth of
bacteria and fungi can be suppressed by an electric field (for
example, refer to Tetsuaki Tsutido, Hiroki Kourai, Hideaki
Matsuoka, and Junichi Koizumu, Kodansha: Microbial Control-Science
and Engineering. In addition, for example, refer to Koichi Takagi,
Application of High Voltage and Plasma Technology to Agricultural
and Food Fields, J. HTSJ, Vol. 51, No. 216). In addition, a
potential generating the electric field may cause a current to flow
through a current path formed by moisture or the like or a circuit
formed by a local and micro discharge phenomenon or the like. It is
considered that this current weakens bacteria and suppresses
proliferation of bacteria. The bacteria in the present embodiment
include bacteria, fungi, or microorganisms such as mites and
fleas.
[0045] Therefore, the spun yarn 10 directly exhibits the
antibacterial effect by the electric field formed inside the spun
yarn 10 or by the electric field generated when approaching an
object having a predetermined potential such as a human body.
Alternatively, the spun yarn 10 allows a current to flow inside or
in the adjacent other fiber, or allows a current to flow when
coming close to an object having a predetermined potential such as
a human body, with moisture such as sweat interposed therebetween.
This current may also directly exhibit the antibacterial effect.
Alternatively, the antibacterial effect may be indirectly exhibited
by an active oxygen species in which oxygen included in moisture is
changed by the action of current or voltage, a radical species
generated by the interaction with an additive included in the fiber
or the catalytic action, or other antibacterial chemical species
such as amine derivatives. Alternatively, an oxygen radical may be
generated in the cell of the bacteria by a stress environment due
to the presence of an electric field or a current. Thus, the spun
yarn 10 may indirectly exhibit the antibacterial effect. Generation
of a superoxide anion radical (active oxygen) or a hydroxy radical
is considered as the radical. The term "antibacterial" used in the
present embodiment is a concept including both an effect of
suppressing generation of bacteria and an effect of killing
bacteria.
[0046] The spun yarn 10 has the piezoelectric fiber that generates
charges by extending and contracting, and therefore a power supply
is unnecessary, and there is no risk of electric shock. The life of
the piezoelectric fiber lasts longer than the antibacterial effect
of the chemical agent or the like. In addition, the piezoelectric
fiber has lower risk of an allergic reaction than a drug.
[0047] In the spun yarn 10, each of the short fibers 11 is
disconnected in the middle of the axial direction 101 of the spun
yarn 10 in the spun yarn 10. The end portions (for example, the
first end 71 and the second end 72 shown in FIGS. 1(A) and 1(B)) of
the short fiber 11 are exposed from the side surface to the
periphery of the spun yarn 10. The end portions of the large number
of the short fibers 11 are exposed to the side surface of the spun
yarn 10, and therefore the side surface of the spun yarn 10 has a
so-called fluff structure. This can adjust the touch and appearance
of the spun yarn 10. In addition, the surface area of the spun yarn
10 is increased by fluffing, and therefore moisture and fine
particles are easily adsorbed to the side surface of the spun yarn
10. Thus, the spun yarn 10 is excellent in fine particle collecting
performance, and can efficiently exhibit the antibacterial
effect.
[0048] The short fiber 11 may be crimped over the entire
longitudinal direction. The crimped short fiber 11 has a
complicated shape, and therefore they are easily and complicatedly
entangled with each other. Therefore, when an external force
(tension) is applied to the spun yarn 10, tensile, twisting, and
bending forces in various directions are applied to each short
fiber 11. Therefore, each short fiber 11 generates charges of
various magnitudes, thereby allowing various electric fields to be
generated between the respective short fibers 11.
[0049] The number of crimps of the short fiber 11 is preferably
0/inch to 20/inch, and the size of the crimp (crimp ratio) is
preferably 0% to 20%.
[0050] In addition, the spun yarn 10 including the plurality of
crimped short fibers 11 has a larger void 41 formed between the
plurality of the short fibers 11 than that including the plurality
of uncrimped short fibers 11. Thus, the antibacterial effect of the
spun yarn 10 is improved as compared with the case of including the
plurality of uncrimped short fibers 11.
[0051] As described above, in the carding step, a part of the short
fibers 11 among the plurality of the short fibers 111 are aligned
in a certain direction. The short fibers 111 aligned in a certain
direction are twisted in the spinning step to be whirled leftward
at 45 degrees to the axial direction 101 of the spun yarn 10. The
proportion of the short fibers 111 along the same direction in the
spun yarn 10 is more increased with increasing proportion of the
short fibers 111 aligned in a certain direction in the carding step
among the plurality of the short fibers 11. When the spun yarn 10
has many short fibers 111 whirled leftward at 45 degrees, negative
charges are generated on the entire surface of the spun yarn 10.
Thus, the polarity of the charge generated on the surface of the
spun yarn 10 can be controlled by changing the proportion of the
short fibers 111 in the spun yarn 10 in the carding step.
[0052] The angle of the axial direction of the short fiber 111 to
the axial direction 101 of the spun yarn 10 can be changed by the
number of twists of the spun yarn 10. The angle of inclination of
the extending direction 900 of the short fiber 111 to the axial
direction 101 of the spun yarn 10 is more increased with increasing
number of twists of the spun yarn 10.
[0053] The thickness of each short fiber 11 may be the same or
different. In addition, the thickness of each short fiber 11 is not
necessarily uniform.
[0054] As the yarn that generates a negative charge on the surface,
a Z yarn using PDLA is also conceivable in addition to an S yarn
using PLLA. In addition, as the yarn that generates a positive
charge on the surface, an S yarn using PDLA is conceivable in
addition to the Z yarn using PLLA.
[0055] A spun yarn 50 according to a second embodiment will be
described below. FIG. 5(A) is a view showing a configuration of a
spun yarn 50 according to the second embodiment, and FIG. 5(B) is a
sectional view of the spun yarn 50 taken along line II-II of FIG.
5(A). In FIG. 5(A), the short fiber 11 is indicated by hatching. In
the description of the spun yarn 50, only differences from the
first embodiment will be described, and description of similar
points will be omitted.
[0056] The spun yarn 50 includes a plurality of the short fibers 11
that are piezoelectric fibers and a plurality of the short fibers
51 that are normal fibers (i.e., not piezoelectric fibers). In this
example, the short fiber 111 in the first embodiment is the short
fiber 11, and the short fibers 112 and 113 in the first embodiment
are the short fiber 51. The normal fiber is a yarn having no
piezoelectricity. Examples of the normal fibers include natural
fibers such as cotton and hemp, animal fibers such as animal hair
and silk, chemical fibers such as polyester and polyurethane,
regenerated fibers such as rayon and cupra, semi-synthetic fibers
such as acetate, and twisted yarns obtained by twisting these
fibers. The strength and the degree of extension and contraction of
the spun yarn 50 can be adjusted according to the usage mode with
selecting the material of the short fibers 51.
[0057] The normal fiber as the material of the short fiber 51 is
preferably composed of a material having higher hydrophilicity than
the piezoelectric fiber as the short fiber 11. That is, the short
fibers 112 and 113 are composed of a material having higher
hydrophilicity than PLLA constituting the short fiber 111.
Therefore, the spun yarn 50 has higher hydrophilicity than the spun
yarn composed only of PLLA. When the hydrophilicity of the spun
yarn 50 is increased, moisture easily penetrates into the spun yarn
50. Therefore, the collecting performance of the spun yarn 50 is
enhanced, and moisture and fine particles are easily adsorbed to
the side surface of the spun yarn 50 and the void 41.
[0058] When moisture enters the void 41 of the spun yarn 50, the
spun yarn 50 swells. Conversely, when moisture is vaporized and
discharged to the outside from the void 41 of the spun yarn 50, the
spun yarn 50 contracts. When the spun yarn 10 swells or contracts,
each of the short fibers 11 in the spun yarn 50 extends and
contracts. Each short fiber 11 extends and contracts, and therefore
a local electric field is generated inside the spun yarn 50. The
bacteria taken into the spun yarn 50 are killed or deactivated by
the electric field. Therefore, the spun yarn 50 has a larger
specific surface area than a yarn composed of only long fibers, is
excellent in fine particle collecting performance, and can
efficiently exhibit the antibacterial effect against bacteria and
the like by the charge generated by each short fiber 11.
[0059] A spun yarn 60 according to a third embodiment will be
described below. FIG. 6 is a view showing a configuration of the
spun yarn 60. In the description of the spun yarn 60, only
differences from the spun yarn 10 of the first embodiment will be
described, and description of the same points will be omitted.
[0060] As shown in FIG. 6, the spun yarn 60 includes a short fiber
111 and a short fiber 61. The short fiber 61 is shorter than the
short fiber 111. The short fiber 111 and the short fiber 61 are
twisted together. The short fiber 111 is long, and thus is whirled
along a relatively same direction as the axial direction 101 of the
spun yarn 60. Most of the short fibers 111 are inclined leftward to
the axial direction 101 of the spun yarn 60, and therefore most of
the short fibers 111 generate negative charges on the surface when
extended in the axial direction 101 of the spun yarn 60. Whereas,
the short fiber 61 is short, and thus include those that are
whirled along a random direction in the axial direction 101 of the
spun yarn 60. Thus, the short fiber 61 includes many fibers
inclined rightward to the axial direction 101 of the spun yarn 60
as compared with the short fiber 111, and therefore the short fiber
61 includes a part of fibers that generate positive charges on the
surface when extended in the axial direction 101 of the spun yarn
60. Therefore, the spun yarn 60 can locally generate an electric
field between the short fiber 111 and the short fiber 61. Examples
of the spun yarn 60 include two types of the short fibers including
the short fiber 111 and the short fiber 61; however, the length of
the short fiber is not limited to two types, and the spun yarn
includes three or more types of lengths.
[0061] Hereinafter, an antibacterial yarn 70 will be described.
FIG. 7(A) is a part of an exploded view showing a configuration of
the antibacterial yarn, and FIG. 7(B) is a sectional view of the
short fiber 111.
[0062] As shown in FIG. 7(A), the antibacterial yarn 70 includes a
spun yarn 10 and a spun yarn 20. The antibacterial yarn 70 is a
yarn (Z yarn) in which the spun yarn 10 and the spun yarn 20 are
whirled leftward each other.
[0063] In the antibacterial yarn 70, the spun yarn 10 includes many
short fibers 111 that are whirled while being inclined leftward at
0 degrees to 80 degrees, and preferably at 20 degrees to 50
degrees, and generates negative charges on the entire surface of
the spun yarn 10 when extended. The spun yarn 20 is a leftward
whirled yarn (Z yarn) obtained by whirling the short fibers 11
leftward. The spun yarn 20 includes many short fibers whirled while
being inclined rightward at 0 degrees to 80 degrees, and preferably
at 20 degrees to 50 degrees, and generates positive charges on the
entire surface of the spun yarn 20 when extended.
[0064] In the spun yarn 10 and the spun yarn 20, the inclination of
the extending direction 900 of the short fiber 11 to the axial
direction 101 can be adjusted by the number of twists of the spun
yarn 10, the spun yarn 20, and the antibacterial yarn 70. The
number of twists of the antibacterial yarn 70 is preferably smaller
than the number of twists of the spun yarn 10 and the spun yarn 20.
For example, the extending direction 900 of each short fiber 11 is
preferably adjusted so as to be finally inclined by 45 degrees to
the axial direction 103 of the antibacterial yarn 70. As a result,
when the antibacterial yarn 70 is extended in the axial direction
103 of the antibacterial yarn 70, each of the short fibers 11 can
effectively generate a charge.
[0065] The spun yarn 20 is a Z yarn using PLLA; however, the spun
yarn 20 may be an S yarn using PDLA. The spun yarn 10 and the spun
yarn 20 are the same S yarn, and therefore the angle between the
yarns can be easily adjusted when producing the antibacterial yarn
70. The spun yarn 10 may be a Z yarn using PDLA. In this case, the
spun yarn 10 and the spun yarn 20 are the same Z yarn, and
therefore the angle between the yarns can be easily adjusted when
producing the antibacterial yarn 70.
[0066] The antibacterial yarn 70 is formed by twisting the spun
yarn 10 that generates a negative charge on the surface and the
spun yarn 20 that generates a positive charge on the surface with
each other, and therefore a strong electric field can be generated
by the only antibacterial yarn 70. In each yarn of the spun yarn 10
and the spun yarn 20, an electric field formed between the inside
and the surface of the spun yarn 10 or the spun yarn 20 leaks into
the air. The electric fields generated by the spun yarn 10 and the
spun yarn 20 are coupled. A strong electric field is formed at a
proximity position of the spun yarn 10 and the spun yarn 20, and
the antibacterial yarn 70 exhibits the antibacterial effect.
[0067] The structure of the twisted yarn is complicated, and the
proximity positions of the spun yarn 10 and the spun yarn 20 are
not uniform. In addition, when tension is applied to the spun yarn
10 or the spun yarn 20, the proximity position also changes. This
changes the intensity of the electric field in each position, and
generates an electric field having a broken symmetric shape. The
yarn (S yarn) in which the spun yarn 10 and the spun yarn 20 are
twisted rightward can similarly generate an electric field by the
only yarn. The number of twists of the spun yarn 10, the number of
twists of the spun yarn 20, or the number of twists of the
antibacterial yarn 70 obtained by twisting these yarns are
determined in view of the antibacterial effect.
[0068] The plurality of the short fibers 11 constituting the spun
yarn described above has a portion in which the short fibers 11 are
in contact with each other. In the short fibers 11 in contact with
each other, the static friction coefficient of one short fiber 11
is designed to be higher than the static friction coefficient of
the other short fiber 11. For example, the static friction
coefficient of the short fiber 111 is higher than the static
friction coefficients of the short fiber 112 and the short fiber
113. This can suppress the relative movement between the short
fibers 11 in contact with each other, and the short fiber 11 can
efficiently apply the shear stress to the spun yarn 10.
[0069] In addition, as shown in FIG. 7(B), the short fiber 111
among the short fibers 11 is a yarn having a heteromorphic section.
At least one of the short fiber 111, the short fiber 112, and the
short fiber 113 in contact with each other may be a yarn having a
heteromorphic section, or all may have yarns having heteromorphic
sections. The yarn having a heteromorphic section is a yarn having
a cross section such as a cross shape, a star polygon, or a concave
polygon. In any example, the yarn having a heteromorphic section
has a groove or a projection extending in the longitudinal
direction of the yarn having a heteromorphic section. Herein, the
yarn having a heteromorphic section may have both the groove
portion and the projection portion. For example, the short fiber
111 has a groove 74 and projection 75. This easily entangles the
short fibers 11 with each other, and the short fiber 11 can
efficiently apply shear stress to the spun yarn 10.
[0070] Hereinafter, an antibacterial cloth 80 will be described
below. FIG. 8 is a view showing a configuration of the
antibacterial cloth 80.
[0071] As shown in FIG. 8, the antibacterial cloth 80 includes a
plurality of the spun yarns 10 and a plurality of the spun yarns
20. The spun yarn 10 and the spun yarn 20 are the same as those
described for the antibacterial yarn 70, and therefore the
description thereof will be omitted.
[0072] In the antibacterial cloth 80, portions other than the spun
yarn 10 and the spun yarn 20 are non-piezoelectric fibers. Herein,
the non-piezoelectric fiber includes those that generate no charge
from natural fibers such as cotton and wool, which are widely used
as yarns, or from synthetic fibers. The non-piezoelectric fiber may
include those that generate weak charges as compared with the spun
yarn 10 and the spun yarn 20. In the antibacterial cloth 80, the
spun yarn 10 and the spun yarn 20 are woven together with the
non-piezoelectric fiber in a state of being alternately arranged in
parallel.
[0073] In the antibacterial cloth 80, the warp is the spun yarn 10,
the spun yarn 20, and the non-piezoelectric fiber, and the weft is
the non-piezoelectric fiber. The non-piezoelectric fiber is not be
woven necessarily as the warp, and only the spun yarn 10 and the
spun yarn 20 may be woven. In addition, the weft yarn is not
limited to the non-piezoelectric fiber, and may include the spun
yarn 10 or the spun yarn 20.
[0074] When the antibacterial cloth 80 is extended in a direction
parallel to the warp, charges are generated from the spun yarn 10
and the spun yarn 20. In each yarn of the spun yarn 10 and the spun
yarn 20, an electric field formed between the inside and the
surface of the yarn leaks into the air. The electric fields
generated by the spun yarn 10 and the spun yarn 20 are coupled. A
strong electric field is formed at proximity portions of the spun
yarn 10 and the spun yarn 20. Thus, the antibacterial cloth 80
exhibits the antibacterial effect.
[0075] In the antibacterial cloth 80, the surfaces of the spun yarn
10 and the spun yarn 20 are fluffed. The contact area between the
spun yarn 10, the spun yarn 20, and the non-piezoelectric fiber is
larger as compared with the case where the spun yarn 10 and the
spun yarn 20 are not fluffed. Therefore, when the antibacterial
cloth 80 is extended, the spun yarn 10 and the spun yarn 20 are
pulled although the antibacterial cloth 80 is not fully extended.
Therefore, although a load applied to the antibacterial cloth 80 is
small, the antibacterial cloth 80 can generate an electric
field.
[0076] The antibacterial cloth 80 is not limited to a woven fabric.
Examples of the antibacterial cloth 80 include a knitted fabric
knitted by using the spun yarn 10 and the spun yarn 20 as knitting
yarns, and a nonwoven fabric including the spun yarn 10 and the
spun yarn 20.
[0077] The spun yarn 10, the spun yarn 20, the spun yarn 50, the
spun yarn 60, the antibacterial yarn 70, or the antibacterial cloth
80 described above are applicable for products such as various
clothes or medical members. For example, the spun yarn 10, the spun
yarn 20, the spun yarn 50, the spun yarn 60, the antibacterial yarn
70, or the antibacterial cloth 80 is applicable for masks,
underwear (particularly socks), towels, insoles such as shoes and
boots, sportswear in general, hats, bedclothes (including beddings,
mattresses, sheets, pillows, and pillows covers), toothbrushes,
froth, a filter of a water purifier, an air conditioner, or an air
purifier, stuffed animals, pet-related products (mat for pet,
clothing for pet, and inner of clothing for pet), various mat
products (foot, hand, toilet seat, or the like), curtains, kitchen
utensils (sponge, cloth, or the like), seats (seats for cars,
trains, airplanes, or the like), a cushioning material of a
motorcycle helmet and an exterior material thereof, sofa, bandage,
gauze, suture, doctor's and patient's clothing, supporters,
sanitary products, sporting goods (inner of a wear and a glove, a
glove used in martial arts, or the like), a filter for an air
conditioner or an air purifier, a packaging material, or a screen
door.
[0078] Finally, the description of the present embodiment is to be
considered in all respects as illustrative and not restrictive. The
scope of the present invention is defined not by the above
embodiments but by the claims. Furthermore, the scope of the
present invention is intended to include meaning equivalent to the
scope of the claims and all modifications within the scope.
DESCRIPTION OF REFERENCE SYMBOLS
[0079] 10, 20, 50, 60: Spun yarn [0080] 11, 51, 61: Short fiber
[0081] 70: Antibacterial yarn [0082] 80: Antimicrobial cloth [0083]
111: First short fiber [0084] 112: Second short fiber [0085] 113:
Third short fiber
* * * * *