US20220267934A1

US20220267934A1 - Spun yarn, and yarn and cloth including spun yarn

Info

Publication number: US20220267934A1
Application number: US17/653,000
Authority: US
Inventors: Kenichiro Takumi; Masayuki Tsuji; Eiji Taguchi; Tomoharu KIDOU
Original assignee: Murata Manufacturing Co Ltd
Current assignee: Murata Manufacturing Co Ltd
Priority date: 2019-12-20
Filing date: 2022-03-01
Publication date: 2022-08-25
Also published as: WO2021125195A1; JP7180792B2; JPWO2021125195A1; CN114051543B; CN114051543A

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.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

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

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

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.
Patent Document 1: Japanese Patent Application Laid-Open No. 2018-090950

SUMMARY OF THE INVENTION

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.
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.
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.
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.
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.
The present invention can efficiently exhibit an antibacterial effect.

BRIEF EXPLANATION OF THE DRAWINGS

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).

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.

FIG. 3 illustrates shear stress generated in each piezoelectric fiber when tension is applied to a spun yarn.

FIG. 4 is a sectional view schematically showing a part of a spun yarn for explaining an antibacterial mechanism in the spun yarn.

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).

FIG. 6 is a view showing a configuration of a spun yarn according to a third embodiment.

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.

FIG. 8 is a view showing a configuration of an antibacterial cloth.

DETAILED DESCRIPTION OF THE INVENTION

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.
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.
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.
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 d₁₄and d₂₅as piezoelectric strain constants. Therefore, polylactic acid generates charges most efficiently when strain occurs in a direction of 45 degrees to the uniaxially extended direction.
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.
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.
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.
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.
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.
The fineness of the short fiber 11 is preferably 0.3 dtex to 10 dtex.
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.
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).
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.
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.
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.
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.
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.
Each of the short fiber 111, the short fiber 112, and the short fiber 113 preferably has a fiber count of 1 to 500.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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%.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
Hereinafter, an antibacterial cloth 80 will be described below. FIG. 8 is a view showing a configuration of the antibacterial cloth 80.
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.
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.
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.
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.
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.
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.
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.
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

- 10, 20, 50, 60: Spun yarn
- 11, 51, 61: Short fiber
- 70: Antibacterial yarn
- 80: Antimicrobial cloth
- 111: First short fiber
- 112: Second short fiber
- 113: Third short fiber

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.