JP7340183B1 - Core-sheath type polyester composite fiber and its manufacturing method - Google Patents

Abstract

The present invention provides a core-sheath type polyester composite fiber that has sufficient electrical conductivity and strength, and is also excellent in electrical conductivity after washing 100 times. The core-sheath type polyester composite fiber of the present invention consists of a core part and a sheath part, and the core part is made of polyester having ethylene terephthalate as a main repeating unit and containing 1 to 15 mol% of isophthalic acid per 100 mol% of the acid component. The sheath is made of a core-forming composition that mainly contains resin, and the sheath is made of a sheath-forming composition that mainly contains polybutylene terephthalate and 20 to 35% by mass of a conductive component. The area ratio (core/sheath) of the core and sheath in a cross section perpendicular to the longitudinal direction of the strip is 60/40 to 90/10, and the following physical properties (a) to (c) are satisfied. All are satisfied. (a) The breaking strength of the composite fiber is 3.0 cN/dtex or more (b) The degree of crystallinity of the composite fiber is 27 to 37% (c) The initial electrical resistance value of the composite fiber is 5.0 x 10 8 Ω/ cm or less

Description

The present invention relates to conductive composite fibers consisting of a conductive component and a non-conductive component, and specifically relates to clothing products such as anti-static work clothes and uniforms, interior products such as carpets and curtains, The present invention relates to a core-sheath type polyester composite fiber that can be widely used in various industrial materials, etc., and a method for producing the same.

Fibers made of hydrophobic polymers such as polyester, polyamide, and polyolefin have many advantages such as mechanical properties, chemical resistance, and weather resistance, and are widely used not only for clothing but also for industrial materials. There is. However, these fibers generate a significant amount of static electricity due to friction, etc., so they can attract dust from the air, degrading the aesthetic appearance, giving the human body an electric shock, causing discomfort, and even causing damage to electronic devices due to sparks. This can cause problems such as damage to flammable materials and ignition and explosion of flammable materials. Therefore, many studies have been conducted to impart electrical conductivity.

Until now, fibers have been proposed in which conductive particles such as conductive carbon black or metal powder are dispersed throughout a thermoplastic polymer. When this is done, the stringability and strength and elongation are significantly reduced, making it impractical.

To solve this problem, Patent Documents 1 and 2 propose a core-sheath type composite fiber in which a conductive component is completely wrapped in a non-conductive component, or a type in which a conductive component is partially exposed on the fiber surface. A composite fiber is disclosed.

The composite fibers described in these patent documents have improved strength and elongation due to improved spinnability, but conductive components are not present on the fiber surface or are present only partially. Therefore, the conductive performance was insufficient. In particular, the durability of conductive performance was poor.

On the other hand, Patent Document 3 describes a core-sheath type composite fiber in which a conductive component mixed with carbon black is arranged in the sheath portion for the purpose of improving conductive performance. Generally, when a conductive component is exposed over the entire fiber surface, the spinnability tends to deteriorate, but in Patent Document 3, the arrangement of the conductive component and non-conductive component in the cross-sectional shape is determined under specific conditions. It is stated that by setting the above-mentioned conductive fibers within a range that satisfies the above, it is possible to obtain a conductive fiber that has good passability through the spinning process and post-process, and also has excellent conductivity durability. There is.

In recent years, work clothes used in a variety of jobs, including the electronics industry, are frequently worn and washed, and have been designed to have wash resistance (durability), with little loss of conductive performance even after repeated wear and washing. There is a need for something that has excellent properties and strength. The conductive fiber described in Patent Document 3 had excellent conductive performance and durability to a certain extent, but its strength was insufficient and the conductive fiber did not have a sufficiently satisfactory performance in terms of conductive performance and durability. Ta. Regarding the durability of conductive performance, it is required for work clothes that the conductive performance after washing 100 times does not deteriorate significantly compared to the initial conductive performance. The conductive fiber described in Patent Document 3 had poor conductive performance especially after washing 100 times.
Thus, to date, no conductive fiber has been proposed that has sufficient conductive performance and strength and is also excellent in conductive performance after washing 100 times.

Japanese Patent Application Publication No. 09-143821 Japanese Patent Application Publication No. 09-279416 Patent No. 4916460

The purpose of the present invention is to solve the above-mentioned problems, and to provide a core-sheath type polyester composite fiber that has sufficient conductive performance and strength, and has excellent conductive performance even after washing 100 times. It is. Another object of the present invention is to provide a manufacturing method for obtaining core-sheath type polyester composite fibers having the above characteristics with good operability.

The present inventors conducted extensive studies to solve the above problems and arrived at the present invention. That is, the present invention has the following gist.

Item 1. A core-sheath type polyester composite fiber consisting of a core part and a sheath part,
The core is composed of a core-forming composition mainly containing a polyester resin whose main repeating unit is ethylene terephthalate and which contains 1 to 15 mol% of isophthalic acid per 100 mol% of the acid component,
The sheath is composed of a sheath-forming composition that mainly contains polybutylene terephthalate and contains 20 to 35% by mass of a conductive component,
The area ratio of the core part and the sheath part (core part/sheath part) in a cross section perpendicular to the longitudinal direction of the yarn is 60/40 to 90/10,
A core-sheath type polyester composite fiber that satisfies all of the physical properties of (a) to (c) below.
(a) The breaking strength of the composite fiber is 3.0 cN/dtex or more (b) The degree of crystallinity of the composite fiber is 27 to 37%
(c) The initial electrical resistance value of the composite fiber is 5.0×10 ⁸ Ω/cm or less. Item 2. Item 1. The core-sheath type polyester composite fiber according to item 1, which further satisfies the following physical property (d).
(d) Electrical resistance value after 100 washes is 1.0×10 ⁹ Ω/cm or less Item 3. Item 3. A woven or knitted fabric comprising the core-sheath type polyester composite fiber according to item 1 or 2.
Item 4. Item 2. The method for producing a core-sheath type polyester composite fiber according to Item 1 or 2, wherein the difference in melt viscosity between the core forming composition and the sheath forming composition (the sheath forming composition) at a shear rate of 1000 s ^-1 at a spinning temperature is The melt viscosity of the core-forming composition (melt viscosity of the core-forming composition) was adjusted to 300 dPa·s ^-1 or less (absolute value), and the core-forming composition and the sheath-forming composition were placed in a composite spinning device. A method for producing a core-sheath type polyester composite fiber, the method comprising supplying a core-sheath type polyester composite fiber, performing melt spinning, and sequentially performing steps (1) to (4) shown below.
Step (1): Step (2) of cooling the undrawn yarn melt-spun from the spinneret nozzle by blowing cooling air at a position 100 to 150 mm downward from the bottom surface of the spinneret nozzle. : Step of winding the cooled undrawn yarn at 2000 to 3000 m/min (3): Step of stretching the wound undrawn yarn 1.2 to 2.0 times while heating it at 50 to 100°C. (4): After heat treating the drawn yarn at 130 to 150°C, wind it up.

The core-sheath type polyester composite fiber of the present invention has sufficient electrical conductivity and strength, and has a degree of crystallinity within a specific range, so that peeling between the core and sheath portions is less likely to occur. Therefore, it has excellent conductivity (durability) even after washing 100 times.
The core-sheath type polyester composite fiber of the present invention can be widely used in clothing products such as anti-static work clothes and uniforms, interior products such as carpets and curtains, and various industrial material products.
Further, according to the method for producing a core-sheath type polyester composite fiber of the present invention, the core-sheath type polyester composite fiber of the present invention that satisfies a specific strength, a specific degree of crystallinity, and a specific initial electrical resistance value is produced. This makes it possible to obtain high quality.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing an example of a composite form of a core-sheath type polyester composite fiber of the present invention in a cross section perpendicular to the longitudinal direction of the yarn. It is a weave structure of the conductive fabric obtained in Example 1.

1. Core-Sheath Type Polyester Composite Fiber The core-sheath type polyester composite fiber (hereinafter sometimes referred to as conductive composite fiber) of the present invention is a core-sheath type composite fiber consisting of a core portion and a sheath portion.

The core is composed of a core-forming composition mainly containing a polyester resin containing ethylene terephthalate as a main repeating unit and 1 to 15 mol% of isophthalic acid per 100 mol% of the acid component. Here, "the main repeating unit is ethylene terephthalate" means that the repeating unit of ethylene terephthalate is 50 mol % or more with respect to all the repeating units constituting the polyester resin. Moreover, "mainly containing polyester resin" means that the core forming composition contains 50% by mass or more of polyester resin.

The polyester resin has ethylene terephthalate as a main repeating unit and contains 1 to 15 mol% of isophthalic acid per 100 mol% of the acid component. The content of repeating units of ethylene terephthalate is preferably 70 mol% or more, more preferably 80 mol% or more, still more preferably 85 mol% or more, even more preferably 90 mol% or more. Isophthalic acid is contained as a copolymerization component, and the content of isophthalic acid is preferably 2 to 12 mol%, more preferably 4 to 12 mol%, even more preferably 6 to 10 mol%, per 100 mol% of the acid component. %. By using a polyester resin copolymerized with isophthalic acid in the above content, the reaction temperature during polycondensation reaction and the temperature during spinning can be lowered. In other words, the difference in melt viscosity with the sheath forming composition constituting the sheath described later can be reduced, the composite spinning process can be performed smoothly, and the crystallinity of the conductive composite fiber is within the range defined by the present invention. It becomes easier to adjust.
When the content of isophthalic acid contained in the polyester resin is less than 1 mol% per 100 mol% of the acid component, the melting point is lowered compared to polyethylene terephthalate (PET) contained in the sheath forming composition. Since the polycondensation reaction temperature and the spinning temperature cannot be lowered, it becomes difficult to perform the composite spinning process smoothly. On the other hand, if the content of isophthalic acid exceeds 15 mol%, the number of amorphous regions in the fiber increases, so the operability during spinning tends to deteriorate, and even if conductive composite fibers can be obtained, The strength and durability of the conductive performance of the conductive composite fibers decrease. Moreover, it becomes difficult to control the boiling water shrinkage rate, and the boiling water shrinkage rate tends to become high.
The polyester resin may contain other copolymer components as long as they do not impair the effects of the present invention. Examples of other copolymerization components include cyclohexanedimethanol (CHDM) and cyclohexanedicarboxylic acid (CHDA).

The content of the polyester resin containing 1 to 15 mol% of isophthalic acid in the core forming composition is 50% by mass or more, preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 85% by mass. % or more, even more preferably 90% by mass or more, particularly preferably 95% by mass or more, and most preferably 100% by mass.

Next, the sheath section will be explained. The sheath exhibiting conductive performance is composed of a sheath-forming composition that mainly contains polybutylene terephthalate and also contains 20 to 35% by mass of a conductive component. Here, "mainly containing polybutylene terephthalate" means that the sheath forming composition contains 50% by mass or more of polybutylene terephthalate.

The content of the conductive component in the sheath forming composition is preferably 22 to 33% by mass, more preferably 22 to 30% by mass, and even more preferably 23 to 27% by mass. By adjusting the content of the conductive component within the above range, it becomes easy to adjust the initial electrical resistance value of the conductive conjugate fiber within the range defined by the present invention. If the content of the conductive component is less than 20% by mass, sufficient conductive performance cannot be imparted. On the other hand, if the content of the conductive component exceeds 35% by mass, it will be difficult to uniformly disperse the conductive component in the sheath forming composition, resulting in separation of the core and sheath and problems during the spinning and drawing process. Fiber breakage is likely to occur, and the resulting conductive composite fiber has poor strength and durability in terms of conductivity. Further, sufficient conductive performance may not be obtained in some cases.

Examples of the conductive component used in the present invention include conductive carbon black, metal powder (silver, nickel, copper, iron, tin, or alloys thereof, etc.), copper sulfide, copper iodide, zinc sulfide, and cadmium sulfide. Examples include metal compounds such as. Further, conductive particles may be made by adding a small amount of antimony oxide to tin oxide or adding a small amount of aluminum oxide to zinc oxide. Furthermore, it is also possible to use conductive particles obtained by coating the surface of titanium oxide with tin oxide and mixing and firing antimony oxide. Among them, conductive carbon black (e.g., acetylene black, Ketjen black, etc.) is widely used to improve the performance of conductive fibers and is less likely to inhibit the fluidity of polymers than metal particles. preferable.

The specific resistance value of the conductive component is preferably 1×10 ⁴ Ω·cm or less, more preferably 1×10 ² Ω·cm or less. If a specific resistance value exceeds 1×10 ⁴ Ω・cm, it may be necessary to disperse a large amount of conductive particles in the polymer in order to obtain the desired conductive performance. Not only does this have a negative effect on the physical properties of the fibers, but also yarn breakage occurs during spinning and drawing, which may cause problems in operability.

As the conductive component, it is preferable to use conductive carbon black. The conductive carbon black preferably has an average particle size of 1 μm or less, more preferably 0.5 μm or less. When the average particle size exceeds 1 μm, the dispersibility of the conductive carbon black in the resin tends to deteriorate, and the conductive performance and strength and elongation properties of the conductive composite fiber tend to deteriorate.

In the present invention, polybutylene terephthalate (PBT) is mainly used as the resin constituting the sheath. Since PBT is a highly crystalline resin, the conductive components contained therein tend to be uniformly arranged in PBT, and the resulting conductive composite fibers have excellent conductivity (low electrical resistance). , the fibers have uniform electrical conductivity in the longitudinal direction.

PBT may contain a copolymer component as long as it does not impair the effects of the present invention, but it is preferable that it does not contain a copolymer component. Examples of copolymerization components include ethylene glycol (EG), cyclohexanedimethanol (CHDM), cyclohexanedicarboxylic acid (CHDA), isophthalic acid (IPA), 1,3-propanediol, sebacic acid, dimer acid, and dodecanedioic acid. , xylylene glycol, polytetramethylene glycol, polyethylene glycol, epsilon caprolactam, and the like.

The content of PBT in the sheath forming composition is 50% by mass or more, preferably 55% by mass or more, more preferably 60% by mass or more, even more preferably 65% by mass or more, even more preferably 70% by mass. The content is particularly preferably 75% by mass or more. Note that the resin constituting the sheath portion may contain polyethylene terephthalate or copolymerized polyester resin as a polyester resin other than PBT, as long as the effects of the present invention are not impaired. However, in the present invention, it is preferable to use only PBT as the resin constituting the sheath.

The core forming composition and the sheath forming composition may contain waxes, polyalkylene oxides, various surfactants, dispersants such as organic electrolytes, antioxidants, etc., depending on the purpose, to the extent that the effects of the present invention are not impaired. It may contain stabilizers such as UV absorbers, colorants, pigments, fluidity improvers, and other additives.

In the conductive composite fiber of the present invention, the sheath portion is arranged to cover at least a portion of the surface of the core portion. From the viewpoint of improving conductive performance, the covering ratio of the sheath to the surface of the core is preferably 90% or more of the surface area of the core, more preferably 95% or more, still more preferably 98% or more, and most preferably It is 100%. That is, it is most preferable that the sheath portion is arranged so as to cover the entire surface of the core portion.
FIG. 1 is a schematic diagram showing an example of the composite form of the core-sheath type polyester composite fiber of the present invention in a cross section perpendicular to the longitudinal direction of the yarn. FIG. 1 shows a state in which the conductive sheath 1 covers the entire surface of the non-conductive core 2 (that is, the coverage of the sheath with respect to the core surface is 100%). Further, as shown in FIG. 1, it is preferable that the sheath portion 1 has a substantially uniform thickness and width without having a protrusion protruding toward the center of the cross section. When the coverage of the core surface of the sheath is less than 90% of the surface area of the core, the conductive performance is likely to be insufficient and the durability of the conductive performance is also likely to be poor.

The conductive composite fiber of the present invention has a core to sheath area ratio (core/sheath) in a cross section perpendicular to the longitudinal direction of the fiber (cross section cut perpendicularly). It is 60/40 to 90/10. The area ratio of the core to the sheath is preferably 65/35 to 85/15, more preferably 70/30 to 85/15, even more preferably 75/25 to 85/15. . When the area ratio of the sheath containing the conductive component is less than 10%, the proportion of the core polyester resin exposed on the fiber surface increases, operability deteriorates, and the resulting conductive composite fiber has poor conductivity. It will be inferior to In addition, when conductive composite fibers are used as part of woven or knitted fabrics, the electrical conductivity between the seams becomes poor because the electrical conductivity at the points of contact between the conductive composite fibers between the seams is insufficient. . Furthermore, repeated use further deteriorates the conductive performance, making it unsatisfactory for practical use. On the other hand, if the area ratio of the sheath portion exceeds 40%, yarn breakage occurs during spinning or drawing, resulting in poor operability. Furthermore, even if composite fibers are obtained, the yarn properties such as strength and elongation properties are inferior.

Further, the conductive composite fiber of the present invention preferably has a single fiber fineness of 3.0 to 6.0 dtex, more preferably 4.0 to 5.5 dtex, and 4.5 to 5.5 dtex. It is even more preferable that there be. Further, the total fineness of the multifilament yarn is preferably 15 to 40 dtex, more preferably 20 to 35 dtex, and even more preferably 25 to 32 dtex. By setting the single fiber fineness of the conductive composite fiber and the total fineness of the multifilament yarn within the above range, the woven or knitted fabric obtained using the conductive composite fiber as a part can improve the conductivity contained in the fiber sheath. The color of the ingredients becomes less noticeable, resulting in an excellent appearance. In addition, in the present invention, by employing the method for manufacturing a conductive composite fiber described below, it is possible to obtain a conductive composite fiber having a relatively small single fiber fineness as described above, and It can be made into a conductive composite fiber having fiber strength.
The single fiber fineness and total fineness of the conductive composite fiber in the present invention are values measured based on "Method A" of JISL1013:2010 Chemical Fiber Filament Yarn Test Method "8.3.1 Positive Fineness", respectively. be.

The conductive composite fiber of the present invention is preferably used as at least a part of the fibers constituting the woven or knitted fabric, but the conductive composite fiber may be used as it is, or the conductive composite fiber may be combined with other fibers. You may use combination twisting, covering, or mixed fibers. In addition, in consideration of the durability of conductive performance, it is preferable to use the conductive composite fiber by twisting, covering, or mixing with other fibers. Other fibers are not particularly limited, and include synthetic fibers such as polyamide, polyester, and polyethylene, recycled fibers such as rayon, and natural fibers such as cotton, hemp, and wool. Since the fibers are made of polyester resin, polyester fibers are preferred.

When using the conductive composite fiber of the present invention by twisting, covering, or mixing with other fibers, in order to fully exhibit the conductive performance of the conductive composite fiber of the present invention, the conductive composite fiber of the present invention must be The ratio of conjugate fibers to other fibers (conductive conjugate fibers/other fibers) is preferably 5/95 to 75/25. Further, at this time, it is preferable to expose as much of the conductive composite fiber of the present invention to the surface as possible.

2. Physical properties of core-sheath type polyester composite fiber The conductive composite fiber of the present invention satisfies all of the following physical properties (a) to (c).
(a) The breaking strength of the composite fiber is 3.0 cN/dtex or more (b) The degree of crystallinity of the composite fiber is 27 to 37%
(c) The electrical resistance value of the composite fiber is 5.0 x 10 ⁸ Ω/cm or less. By satisfying all of these characteristics, it has high strength, excellent conductive performance, and conductive performance after 100 washes. It can be made into a conductive composite fiber that has excellent durability. A conductive composite fiber that satisfies all of these characteristics can be obtained by the manufacturing method of the present invention described below.

As for the physical property (a), the conductive composite fiber of the present invention has a breaking strength of 3.0 cN/dtex or more. The breaking strength is preferably 3.1 cN/dtex or more, more preferably 3.15 cN/dtex or more, even more preferably 3.2 cN/dtex or more, and 3.3 cN/dtex or more. It is particularly preferable. In the present invention, the upper limit of the breaking strength of the conductive composite fiber is not particularly limited, but is approximately 6.5 cN/dtex, and in one embodiment is 5.5 cN/dtex or less, 4.5 cN/dtex or less, or 4.5 cN/dtex or less. It is 0 cN/dtex or less. If the breaking strength is less than 3.0 cN/dtex, if clothing made using conductive composite fibers is used for applications that require frequent use or washing (for example, uniform applications, etc.), it may cause damage during repeated use. Since thread breakage is likely to occur, the clothing has poor conductive performance and durability. Furthermore, problems such as yarn breakage occur during processing steps such as weaving, knitting, and false twisting, resulting in poor process passability. In the present invention, the core forming composition is used as a constituent material of the core, the sheath forming composition is used as a constituent material of the sheath, and the area ratio of the core and the sheath is adjusted to the above specific range. Furthermore, by employing a method for producing a conductive composite fiber which will be described later, the breaking strength of the conductive composite fiber can be adjusted to the above range.
The breaking strength of the conductive composite fiber in the present invention is a value measured according to JIS-L-1013:2010 Chemical fiber filament yarn test method 8.5 "Tensile strength and elongation" 8.5.1 "Standard time test" It is. Specifically, it is a value obtained by using a conductive composite fiber as a sample and measuring the strength when the sample breaks due to elongation using a tensile tester under conditions of a sample thread length of 10 cm and a tensile speed of 10 cm/min.

As for the physical property (b), the conductive composite fiber of the present invention has a crystallinity of 27 to 37%. The degree of crystallinity is preferably 28 to 36%, more preferably 29 to 35%, even more preferably 30 to 35%. When the degree of crystallinity is within this numerical range, the conductive component can sufficiently exhibit conductivity, so that the initial electrical resistance value (c) described later is satisfied. Furthermore, since the degree of crystallinity is within this numerical range, even if the sheath is composed of a sheath-forming composition containing 20 to 35% by mass of a conductive component, separation between the core and sheath occurs. It is presumed that a conductive conjugate fiber that is hard to resist, has high strength, and has excellent durability in conductive performance can be obtained. Furthermore, since the degree of crystallinity is within this numerical range, yarn breakage is less likely to occur when subjected to a false twisting process or a weaving/weaving process, resulting in good process passability.
When the degree of crystallinity is less than 27%, the conductive performance of the conductive composite fiber decreases. The reason for this is presumed to be that the amorphous portion in the fiber increases, making it difficult for the conductive component to be uniformly dispersed in the resin. Furthermore, if the crystallinity is less than 27%, the fiber strength will decrease and the fiber will have poor durability in electrical conductivity. On the other hand, if the crystallinity exceeds 37%, the core and sheath tend to separate when washed, and conductive components such as carbon black contained in the sheath tend to fall off. , resulting in fibers with poor conductive performance and durability.
In the present invention, it is important that the conductive composite fiber satisfies the crystallinity within the above range, and by having the crystallinity within this range, the conductive composite fiber obtained has good conductive performance. Not only is it excellent, but it also has excellent strength and durability in terms of conductivity. In the present invention, the core forming composition is used as a constituent material of the core, the sheath forming composition is used as a constituent material of the sheath, and the area ratio of the core and the sheath is adjusted to the above specific range. Further, by employing a method for producing a conductive composite fiber which will be described later, the crystallinity of the conductive composite fiber can be adjusted to the above range.
In addition, the crystallinity degree in this invention refers to the crystallinity degree of a conductive composite fiber obtained by measuring by the measuring method mentioned later using a conductive composite fiber.

The degree of crystallinity in the present invention is obtained by calculating the degree of crystallinity (Xc) using the following formula. Specifically, using a differential scanning calorimeter, 8.5 mg of conductive composite fiber was heated from 25°C to 280°C at a rate of 20°C/min, and the following calorific values and the following formula were used. Calculate.
Crystallinity (Xc) = {(ΔHm-ΔHc)}/140.2}×100(%)
(ΔHm indicates the amount of heat at the melting point, and ΔHc indicates the amount of heat at temperature-rise crystallization.)

As for the physical property (c), the conductive composite fiber of the present invention has an initial electric resistance value of 5.0×10 ⁸ Ω/cm or less. The initial electrical resistance value means the electrical resistance value before washing 100 times. The initial electrical resistance value is preferably 1.0 x 10 ⁸ Ω/cm or less, more preferably 9.0 x 10 ⁷ Ω/cm or less, and 8.0 x 10 ⁷ Ω/cm or less. It is more preferably 7.0×10 ⁷ Ω/cm or less, even more preferably 6.0×10 ⁷ Ω/cm or less, and even more preferably 5.0×10 ⁷ Ω/cm. cm or less, even more preferably 4.0×10 ⁷ Ω/cm or less, particularly preferably 3.0×10 ⁷ Ω/cm or less. If the initial electrical resistance value exceeds 5.0×10 ⁸ Ω/cm, the conductive performance may be insufficient depending on the intended use. When the initial electric resistance value is 5.0×10 ⁸ Ω/cm or less, the surface leakage resistance value of the woven or knitted fabric is low when the woven or knitted fabric is obtained by using the conductive composite fiber at least in part. This makes it possible to almost eliminate charging. On the other hand, the lower limit of the initial electrical resistance value is not particularly limited, but is preferably about 1.0×10 ⁴ Ω/cm. In the present invention, the core forming composition is used as a constituent material of the core, the sheath forming composition is used as a constituent material of the sheath, and the area ratio of the core and the sheath is adjusted to the above specific range, By adjusting the crystallinity of the conductive composite fiber to the above-mentioned specific range and further employing the method for manufacturing the conductive composite fiber described later, it is possible to adjust the initial electrical resistance value of the conductive composite fiber to the above-mentioned range. can.
The initial electrical resistance value of the conductive composite fiber in the present invention is a value measured according to the AATCC76 method (Test Method for Electrical Surface Resistivity of Fabrics). Specifically, the obtained conductive composite fiber is cut into 15 cm pieces in the length direction, and 10 samples are collected. Apply keratin cream to the surface of both ends of the sample, connect the surface parts coated with keratin cream to metal terminals, apply a DC current of 50 V to the sample with a measurement length of 10 cm, measure the current value, and measure the current value as shown below. Calculate the electrical resistance value using the formula. The arithmetic mean value of the calculated electrical resistance values of the 10 samples is set as the initial electrical resistance value.
Electrical resistance value = E/(I x L)
E: Voltage (V) I: Measurement current (A) L: Measurement length (cm)

As for the physical property (d), the conductive composite fiber of the present invention preferably has an electrical resistance value of 1.0 x 10 ⁹ Ω/cm or less, and 5.0 x 10 ⁸ Ω/cm after washing 100 times. It is more preferably at most 2.0×10 ⁸ Ω/cm, even more preferably at most 7.0×10 ⁷ Ω/cm, even more preferably at most 5.0×10 ⁷ Ω /cm or less, even more preferably 4.0×10 ⁷ Ω/cm or less, particularly preferably 3.0×10 ⁷ Ω/cm or less.
The electrical resistance value after 100 washes in the present invention is an electrical resistance value measured by the following method.
The conductive composite fiber of the present invention is covered with a polyester filament at 520 T/M in the Z direction to obtain a conductive fiber covered yarn. Using only the conductive fiber covering yarn, a tubular knitted fabric is knitted using a knitting machine. The obtained tubular knitted fabric is washed 100 times and dried, and then the covering yarn obtained by disassembling the tubular knitting is cut into lengths of 15 cm in the length direction. The cut covering yarn is used as a conductive composite fiber sample after being washed 100 times, and 10 samples are taken. Apply keratin cream to the surface of both ends of the sample, connect the surface parts coated with keratin cream to metal terminals, apply a DC current of 50 V to the sample with a measurement length of 10 cm, measure the current value, and measure the current value as shown below. Calculate the electrical resistance value using the formula. The arithmetic mean value of the calculated electrical resistance values of the 10 samples is taken as the electrical resistance value after washing 100 times. The washing test was conducted in accordance with the "C4M method" of JIS L 1930:2014 Home washing test method for textile products "Washing method for C type standard washing machine", and the drying method was A method (hang drying).
Electrical resistance value = E/(I x L)
E: Voltage (V) I: Measurement current (A) L: Measurement length (cm)

The conductive composite fiber of the present invention preferably has a breaking elongation of 40 to 70%, more preferably 45 to 66%, and even more preferably 50 to 60%. By setting the elongation at break within the above range, for example, a woven or knitted fabric obtained by partially using conductive composite fibers will be strong against rubbing between fibers, will be difficult to tear, and will have improved conductive performance and durability. It is possible to make it have excellent properties. In the present invention, the core forming composition is used as a constituent material of the core, the sheath forming composition is used as a constituent material of the sheath, and the area ratio of the core and the sheath is adjusted to the above specific range. Further, by employing a method for manufacturing a conductive composite fiber which will be described later, the elongation at break of the conductive composite fiber can be adjusted to the above range.
The elongation at break of the conductive composite fiber in the present invention is measured according to JIS-L-1013:2010 Chemical fiber filament yarn test method 8.5 "Tensile strength and elongation" 8.5.1 "Standard time test" It is a value. Specifically, it is obtained by using the obtained conductive composite fiber as a sample and measuring the elongation when the sample breaks due to elongation using a tensile tester under conditions of a sample thread length of 10 cm and a tensile speed of 10 cm/min. It is a value.

The conductive composite fiber of the present invention preferably has a boiling water shrinkage rate of 10% or less, more preferably 9% or less, even more preferably 8% or less, and 7.5% or less. is even more preferable, and particularly preferably 7% or less. If the boiling water shrinkage rate exceeds 10%, there may be large variations in conductive performance due to shrinkage due to heat setting when fabricated into a woven or knitted fabric. The lower limit of the boiling water shrinkage rate of the conductive composite fiber of the present invention is not particularly limited, but it is sufficient that the difference with the boiling water shrinkage rate of other fibers does not become large, and it is preferably approximately 3% or more. In the present invention, the core forming composition is used as a constituent material of the core, the sheath forming composition is used as a constituent material of the sheath, and the area ratio of the core and the sheath is adjusted to the above specific range. Further, by employing a method for manufacturing a conductive composite fiber which will be described later, the boiling water shrinkage rate of the conductive composite fiber can be adjusted to the above range.
The boiling water shrinkage rate of the conductive composite fiber in the present invention is a value measured and calculated by the following method.
The conductive composite fiber is skeined 20 times using a measuring machine, the yarn length L0 is measured under a load of 0.03 (cN/dtex), and then placed in boiling water under no load and treated for 30 minutes. Thereafter, it is air-dried, and the length L1 after shrinkage is measured again under a load of 0.03 (cN/dtex), and the boiling water shrinkage rate is calculated using the following formula.
Boiling water shrinkage rate (%) = [(L0-L1)/L0] x 100

3. Woven or knitted fabric The woven or knitted fabric of the present invention is a woven or knitted fabric that contains at least a portion of the conductive conjugate fiber of the present invention. The content of the conductive composite fibers contained in the woven or knitted fabric of the present invention is preferably 0.1% by mass or more, more preferably 0.5% by mass or more. The upper limit of the content of the conductive conjugate fiber varies depending on the use of the woven or knitted fabric, but for example, for clothing use, it is preferably approximately 30% by mass or less.
The woven or knitted fabric of the present invention can be used, for example, in clothing applications (work clothes, dustproof clothing, clean room clothing, etc.) or industrial material applications (smartphone gloves, smart textiles, charging brushes used in electronic devices, etc.). .

The woven or knitted fabric of the present invention is not particularly limited in its structure, but from the viewpoint of conductive performance, it is preferable to have a structure in which the conductive composite fibers are exposed on the surface of the fabric, or to use conductive composite fibers in both the warp and weft. preferable.
In the case of woven fabrics, examples include plain weave, twill weave, satin weave, dobby weave, double weave, etc. The conductive composite fiber of the present invention is used in either or both of the warp and weft, and conductive fibers are used in the woven fabric. It is preferable to use the composite fibers so that they are arranged at intervals of 10 mm or less, preferably 8 to 1 mm.
In the case of knitted fabrics, any of circular knitting, weft knitting, and warp knitting may be used. In the case of circular knitting and weft knitting, it is preferable that the conductive composite fibers of the present invention are inserted at intervals of 10 mm or less, preferably 8 to 8 mm. The distance is 1 mm.

In addition, the woven or knitted fabric of the present invention has an initial surface leakage resistance value of 5.0×10 ⁸ Ω/cm or less in the vertical direction, horizontal direction, and between seams, as an indicator showing excellent conductive performance. It is preferably 9.0×10 ⁷ Ω/cm or less, more preferably 8.0×10 ⁷ Ω/cm or less, and even more preferably 7.0×10 ⁷ Ω/cm or less. Even more preferably, it is 6.0×10 ⁷ Ω/cm or less, even more preferably 5.0×10 ⁷ Ω/cm or less. In the present invention, the initial surface leakage resistance value means the surface leakage resistance value before washing 100 times.
The initial surface leakage resistance value of the woven or knitted fabric in the present invention is measured in accordance with IEC61340-5-1. Specifically, two electrodes are installed on the surface of a woven or knitted fabric placed on an insulating plate (in the vertical direction, horizontal direction, or between seams), a constant voltage is applied, and the electrical resistance is determined by the current flowing between the electrodes. Measure. The measurement conditions are 23° C., 12% RH, distance between measurements 25 cm (for vertical and horizontal directions) or 30 cm (for between seams), and voltage of 100 V.

Furthermore, the woven and knitted fabric of the present invention has surface leakage resistance values of 1.0 x 10 in the vertical direction, in the horizontal direction, and between seams after washing 100 times, as an indicator showing that it has excellent durability in conductive performance. It is preferably ⁹ Ω/cm or less. The surface leakage resistance values in the vertical and horizontal directions are more preferably 1.0×10 ⁸ Ω/cm or less, even more preferably 8.0×10 ⁷ Ω/cm or less, and 6.0×10 Ω/cm or less. Even more preferably, it is ⁷ Ω/cm or less. The surface leakage resistance value between the seams is more preferably 5.0×10 ⁸ Ω/cm or less, even more preferably 3.0×10 ⁸ Ω/cm or less, and 1.0×10 ⁸ Ω /cm or less is even more preferable.
The surface leakage resistance value of the woven or knitted fabric in the present invention after 100 washes is measured according to IEC61340-5-1 in the same manner as above, and the measurement conditions are also as above.
In addition, washing 100 times is a washing test for woven and knitted fabrics according to "No. 103" of JIS L 0217:1995 Display symbols and display methods for handling of textile products "Appended Table 1 Test method by symbol - Washing method (washing with water)" This is repeated 100 times, and the drying method is F method (tumble drying).

Generally, when a woven or knitted fabric is washed repeatedly, forces such as rubbing or friction are applied to the fiber surface, and at the same time, the gaps between the structures of the woven or knitted fabric are clogged, and the conductive fibers tend to be buried inside the woven or knitted fabric. However, the woven or knitted fabric of the present invention has excellent conductive performance and durability of conductive performance, and has excellent conductive performance even after washing 100 times.

4. Method for manufacturing core-sheath type polyester conjugate fiber The method for manufacturing the conductive conjugate fiber of the present invention will be described below.
In the production method of the present invention, the melt viscosity difference between the core forming composition and the sheath forming composition at a shear rate of 1000 s ^-1 at the spinning temperature (melt viscosity of the sheath forming composition - the core forming composition) is obtained. The melt viscosity of the composition was adjusted to 300 dPa・s ^-1 or less (absolute value), and the core forming composition and the sheath forming composition were supplied to a composite spinning device to perform melt spinning, as shown below. It is important to perform steps (1) to (4) in order.
Step (1): Step (2) of cooling the undrawn yarn melt-spun from the spinneret nozzle by blowing cooling air at a position 100 to 150 mm downward from the bottom surface of the spinneret nozzle. : Step of winding the cooled undrawn yarn at 2000 to 3000 m/min (3): Step of stretching the wound undrawn yarn 1.2 to 2.0 times while heating it at 50 to 100°C. (4): After heat treating the drawn yarn at 130 to 150°C, wind it up.

The melt spinning process will be described below.
First, the polyester resin contained in the core forming composition constituting the core can be obtained by purchasing a commercially available polyester resin or by producing it using a known method for producing copolymerized polyester.

Next, the sheath forming composition constituting the sheath can be obtained by adding a conductive component at the polymerization stage in a known PBT manufacturing method, or by adding a conductive component to the composition obtained by a commercially available or known manufacturing method. Examples include a method in which a conductive component or a master chip containing a conductive component is added to PBT and then melt-kneaded.

Using the core-forming composition and sheath-forming composition obtained in this way, the core-forming composition and the sheath-forming composition are processed, if necessary, by drying or the like to form chips, and then processed using an ordinary composite spinning device, such as an extruder. The mixture is kneaded, melted, and extruded through a core-sheath type spinneret to perform melt spinning to obtain undrawn yarn.
During composite spinning, the melt viscosity difference between the core forming composition and the sheath forming composition at a shear rate of 1000 s ^-1 at the spinning temperature (melt viscosity of the sheath forming composition - melt viscosity of the core forming composition) is determined. It is important to adjust the melt viscosity (melt viscosity) to 300 dPa·s ^-1 or less (absolute value), and melt spinning is performed by supplying the core forming composition and the sheath forming composition to a composite spinning device. That is, by performing composite spinning with a small difference in melt viscosity between the core forming composition and the sheath forming composition (300 dPa·s ^-1 or less (absolute value)), the core and sheath during spinning are The adhesion between the resins improves, the discharge from the tip nozzle becomes smooth, and the obtained undrawn yarn (conductive composite fiber) also becomes less likely to cause separation between the core and sheath. Therefore, the obtained conductive composite fiber has excellent strength and durability of conductive performance.

The melt viscosity difference between the core forming composition and the sheath forming composition at a shear rate of 1000 ^s at the spinning temperature (melt viscosity of the sheath forming composition - melt viscosity of the core forming composition) is The absolute value is 300 dPa・s ⁻¹ or less, preferably 260 dPa・s ⁻¹ or less, more preferably 240 dPa・s ⁻¹ or less, and preferably 200 dPa・s ⁻¹ or less. More preferably, it is 170 dPa·s ⁻¹ or less, even more preferably 120 dPa·s ⁻¹ or less, and particularly preferably 120 dPa·s −1 or less.

The melt viscosity of the core forming composition is preferably 1000 to 2000 dPa s ^-1 , more preferably 1200 to 1800 dPa s ^-1 , even more preferably 1200 to 1500 dPa s ^-1 . On the other hand, the melt viscosity of the sheath forming composition is preferably 800 to 1,800 dPa·s ^-1 , more preferably 1,000 to 1,600 dPa·s ^-1 , and preferably 1,200 to 1,600 dPa·s ^-1 . More preferred. The melt viscosity of the core-forming composition and the sheath-forming composition can be adjusted by appropriately adjusting the type of resin constituting the core and sheath, heat treatment temperature, heat treatment time, pressure, etc. during polymerization of the resin, It can be adjusted within the above range by appropriately adjusting the temperature during compounding, the rotation speed of the kneader, etc. The melt viscosity is a value at a shear rate of 1000 s ⁻¹ at a spinning temperature during melt spinning, and is measured using a constant force capillary extrusion rheometer.

The spinning temperature is preferably 250 to 310°C, more preferably 260 to 290°C, even more preferably 260 to 280°C. If the spinning temperature is too high, the resin in the core and sheath portions will undergo thermal decomposition, making smooth spinning difficult, and the resulting conductive composite fibers will likely have poor physical properties such as strength and elongation, as well as poor conductivity. On the other hand, if the spinning temperature is too low, undissolved substances and the like tend to remain, which tends to cause yarn breakage during spinning.

Next, steps (1) to (4) after melt spinning will be described.
First, in step (1), the undrawn yarn melt-spun from the spinneret nozzle is cooled by blowing cooling air at a position 100 to 150 mm downward from the bottom surface of the spinneret nozzle. is necessary. The position at which the cooling air is blown is more preferably 110 to 130 mm downward from the bottom surface of the nozzle. In the manufacturing method of the present invention, by blowing cooling air downward from the bottom surface of the spinneret nozzle at a position within the above range, it is thought that the spun yarn is appropriately crystallized, and the crystallinity specified in the present invention is It becomes possible to obtain a conductive composite fiber that satisfies the following. That is, unless the cooling air is blown at the position from the bottom surface of the nozzle described above, it will be difficult to obtain a conductive composite fiber that satisfies the degree of crystallinity specified by the present invention, and the breaking strength specified by the present invention will be difficult to obtain. It is also difficult to obtain conductive conjugate fibers having the following characteristics.

The temperature of the cooling air is preferably 0 to 50°C, more preferably 10 to 40°C. If the cooling temperature is too low, it will be difficult to control the temperature and workability, and if it is too high, the cooling will be insufficient and the filamentous properties of the finally obtained conductive composite fiber will be poor. The wind speed of the cooling air is preferably 0.2 to 0.6 m/s, more preferably 0.3 to 0.5 m/s. If the wind speed is too low, cooling will be insufficient, resulting in poor yarn properties of the final conductive composite fiber, while if the wind speed is too high, the cooling air will cause the yarn to sway, resulting in uneven thickness in the longitudinal direction of the yarn. This may cause thread breakage.

After step (1), it is preferable to bundle the cooled undrawn yarn and perform oiling. Further, after oiling, an interlace nozzle or the like may be used to further perform an interlacing treatment as necessary. In the production method of the present invention, by performing oiling while converging, the spinning tension is lowered and the spinnability of the conductive composite fiber is improved.

Examples of the oil used for oiling include mineral oil, and if necessary, an antistatic agent may be added thereto. The amount of oil applied to the fiber surface is preferably in the range of 0.3 to 2% by weight based on the weight of the fiber.

In step (2), the cooled undrawn yarn passed through step (1) is wound at 2000 to 3000 m/min. The winding speed is preferably 2400 to 2900 m/min, more preferably 2600 to 2800 m/min. If the winding speed is less than 2000 m/min, the obtained composite fiber will have low fiber orientation. For this reason, it is necessary to draw at a high magnification in the subsequent drawing step (3), and the electrically conductive conjugate fibers finally obtained are inferior in strength and conductive performance. In addition, if the winding speed exceeds 3000 m/min, the orientation and crystallization of the fibers will progress too much, and the conductive layer will be likely to be cut during stretching in the subsequent step (3), resulting in yarn breakage during stretching. It becomes easier. Furthermore, even if conductive composite fibers can be obtained, they will be inferior in strength and durability in conductive performance.

In step (3), the wound undrawn yarn is stretched 1.2 to 2.0 times while heating it at 50 to 100°C. Among these, it is preferable to stretch 1.4 to 1.8 times while heating at 70 to 100°C, and most preferably to stretch 1.4 to 1.8 times while heating at 85 to 98°C. . By stretching at the temperature and magnification as described above, the conductive component is uniformly arranged in the length direction of the fiber, and a conductive conjugate fiber with superior conductivity and strength can be obtained.

If the temperature during stretching is less than 50°C, stretching cannot be performed with a sufficient amount of heat, making uniform stretching difficult. As a result, the resulting conductive composite fiber has poor strength and conductive performance.
On the other hand, if the temperature during stretching exceeds 100° C., the undrawn yarn becomes slack, winding around a roller, etc. occurs, and yarn breakage occurs easily during stretching. As a result, the resulting conductive composite fiber has poor strength.

Moreover, if the drawing ratio is less than 1.2 times, the undrawn yarn will not be drawn sufficiently, and the crystallinity of the resulting conductive composite fiber will not satisfy the above range. Further, since the obtained fibers have too much elongation, it tends to be difficult to obtain conductive composite fibers having sufficient strength and elongation for practical use. On the other hand, if the stretching ratio exceeds 2.0 times, the resulting conductive composite fiber will have a high degree of crystallinity and will have poor conductivity. Furthermore, thread breakage occurs during stretching, making it difficult to obtain conductive composite fibers.
In the manufacturing method of the present invention, a method can be adopted in which stretching is performed by changing the rotational speed between the first roller and the second roller, and the temperature of the first roller can be set at 50 to 100°C. preferable.

In step (4), the drawn thread is heat-treated at 130 to 150°C and then wound. The heat treatment is preferably carried out at 135 to 145°C. In the manufacturing method of the present invention, the degree of crystallinity of the conductive composite fiber can be brought into the range specified by the present invention by performing heat treatment at a temperature within the above range in the hot drawing step of step (3). It is also possible to lower the boiling water shrinkage rate. If the temperature in the heat treatment is less than 130°C, the resulting conductive composite fiber will have a low degree of crystallinity and a high boiling water shrinkage rate. On the other hand, if the temperature exceeds 150°C, the crystallinity of the resulting conductive composite fiber will be too high and the durability of the conductive performance will also be poor.
In the manufacturing method of the present invention, a method can be adopted in which stretching is performed by changing the rotational speed between the first roller and the second roller, and a heat plate is provided between the first roller and the second roller. It is preferable to perform heat treatment at 130 to 150°C.

By the above manufacturing method of the present invention, the present invention has a breaking strength of 3.0 cN/dtex or more, a crystallinity of 27 to 37%, and an initial electrical resistance value of 5.0×10 ⁸ Ω/cm or less. Conductive composite fibers can be obtained with good operability.

The present invention will be explained in detail by showing Examples and Comparative Examples below. However, the present invention is not limited to the following examples.
In addition, the measurement method or evaluation method of each physical property is as follows.
(1) Melt viscosity of core-forming composition and sheath-forming composition The core-forming composition and sheath-forming composition were dried in a vacuum dryer at 130° C. for 12 hours before measurement. After drying, the shear rate dependence of the melt viscosity (flow curve ) was measured. From the flow curve obtained in the measurement, the melt viscosity at a shear rate of 1000 s ^-1 was calculated.
(2) Breaking strength and breaking elongation Breaking strength and breaking elongation are determined by JIS-L-1013:2010 Chemical fiber filament yarn test method 8.5 "Tensile strength and elongation" 8.5.1 "Standard time test" Measured according to Specifically, using the obtained conductive composite fiber as a sample, using Tensilon RTC-1210 (manufactured by Orientech Co., Ltd.), the strength when the sample was stretched to break under the conditions of a sample yarn length of 10 cm and a tensile speed of 10 cm/min was determined. and elongation were measured.
(3) Crystallinity The crystallinity was determined by heating 8.5 mg of conductive composite fiber from 25°C to 280°C at a rate of 20°C/min using a differential scanning calorimeter (Diamond DSC manufactured by PerkinElmer). It was calculated using the obtained values of each heat amount and the following formula.
Crystallinity (Xc) = {(ΔHm-ΔHc)}/140.2}×100(%)
(ΔHm indicates the amount of heat at the melting point, and ΔHc indicates the amount of heat at temperature-rise crystallization.)
(4) Initial electrical resistance value of conductive composite fiber The initial electrical resistance value of the conductive composite fiber was measured according to AATCC76 method (Test Method for Electrical Surface Resistivity of Fabrics). The obtained conductive composite fiber was cut into 15 cm pieces in the length direction, and 10 samples were collected. Apply keratin cream to the surface of both ends of the sample, connect the surface parts coated with keratin cream to metal terminals, apply a DC current of 50V at a measurement length of 10 cm to the sample, and measure the current value with a microammeter ( (manufactured by ADCMT, 5451), and the electrical resistance value was calculated using the following formula. The arithmetic mean value of the calculated electrical resistance values of the 10 samples was taken as the initial electrical resistance value.
Electrical resistance value = E/(I x L)
E: Voltage (V) I: Measurement current (A) L: Measurement length (cm)
(5) Electrical resistance value of conductive composite fiber after washing 100 times The electrical resistance value of conductive composite fiber after washing 100 times is measured as follows using AATCC76 method (Test Method for Electrical Surface Resistivity of Fabrics). did.
The obtained conductive composite fiber was covered with a polyester filament (manufactured by Unitika Trading Co., Ltd., 167 dtex/48 f) at 520 T/M in the Z direction to obtain a conductive fiber covered yarn. Using only the conductive fiber covering yarn, a tubular knitted fabric was knitted using a knitting machine (manufactured by Koike Kikai Seisakusho, number of needles: 300, hook diameter: 3.5 inches). The obtained tubular knitted fabric was washed 100 times and dried, and then the covering yarn obtained by disassembling the tubular knitting was cut into lengths of 15 cm in the length direction. The cut covering yarn was used as a conductive composite fiber sample after being washed 100 times, and 10 samples were collected. Apply keratin cream to the surface of both ends of the sample, connect the surface part coated with keratin cream to a metal terminal, apply a DC current of 50V to the sample with a measurement length of 10 cm, measure the current value, and measure the current value as described above. The electrical resistance value was calculated from the formula described in "(4) Electrical resistance value of initial conductive composite fiber". The arithmetic mean value of the calculated electrical resistance values of the 10 samples was taken as the electrical resistance value after washing 100 times. The 100-time washing test was performed on the tubular knitted fabric 100 times in accordance with the "C4M method" of the JIS L 1930:2014 Home washing test method for textile products "C-type standard washing machine washing method". The drying method was Method A (hang drying).
(6) Surface leakage resistance value of woven fabric (conductive fabric) using conductive composite fibers Regarding the obtained conductive fabric, initial ( The surface leakage resistance values were measured before washing 100 times) and after washing 100 times. The following samples (a) to (c) were used for the measurements.
[Sample preparation]
Two types of samples (a) and (b) were prepared by cutting the conductive fabric into a rectangle with a long side of 35 cm and a short side of 30 cm under the conditions shown below.
(a) The long side is the vertical direction, and the short side is the horizontal direction. (b) The long side is the horizontal direction, and the short side is the vertical direction. Then, (a) and (b) are placed side by side in the order , (a) and (b) were sewn with double stitches with the long sides facing each other on one side to obtain sample (c).
[Measurement of surface leakage resistance value]
The surface leakage resistance value was measured using a resistance measuring device (Prostat Corporation, USA, resistance measuring system PRS-801) for each sample (a) placed on an insulating plate of 1.0 × 10 ¹² Ω or more. Two electrodes were installed on the surface of (c) in the following directions and distances between measurements, a constant voltage was applied, and the electrical resistance was measured from the current flowing between the electrodes. The measurement conditions were 23° C., 12% RH, and an applied voltage of 100V.
The surface leakage resistance value in the vertical direction was measured using sample (a) at a distance of 25 cm between measurements in the long side direction.
The surface leakage resistance value in the horizontal direction was measured using sample (b) at a distance of 25 cm between measurements in the long side direction.
The surface leakage resistance value between seams was measured using sample (c), with two electrodes installed so as to include one seam sewn with one side double stitch, and a measurement distance of 30 cm in the short side direction. The measurement was carried out.
For washing 100 times, conductive fabrics should be washed according to "No. 103" of JIS L 0217:1995 Display symbols and display methods for handling of textile products "Appended Table 1 Test method by symbol - Washing method (washing with water)" The test was conducted 100 times, and the drying method was F method (tumble drying).
(7) Boiling water shrinkage rate The obtained conductive composite fiber was skeined 20 times using a measuring machine, the yarn length L0 was measured under a load of 0.03 (cN/dtex), and then the boiling water was It was placed inside and treated for 30 minutes. Thereafter, it was air-dried, and the length L1 after shrinkage was measured again under a load of 0.03 (cN/dtex), and the boiling water shrinkage rate was calculated using the following formula.
Boiling water shrinkage rate (%) = [(L0-L1)/L0] x 100
(8) Single fiber fineness and total fineness JISL1013:2010 Chemical fiber filament yarn test method Single fiber fineness and total fineness were measured based on "Method A" of "8.3.1 Positive fineness".
(9) Operability The state of yarn breakage during melt spinning and drawing when obtaining conductive composite fibers was determined as follows based on the number of yarn breakages per spindle during continuous melt spinning for 24 hours. was evaluated on a three-level scale.
○: The number of thread breakages was 10 or less.
Δ: The number of thread breakages was 11 to 19 times.
×: The number of thread breakages was 20 or more.
(10) Observation of cross-sectional shape The cross-section perpendicular to the longitudinal direction of the obtained conductive composite fiber was observed using a digital microscope "VHX-600" manufactured by Keyence Corporation (magnification: 1000 times).

Example 1
(1) Production of core forming composition A slurry of terephthalic acid (TPA) and ethylene glycol (EG) was supplied to an esterification reactor and reacted at a temperature of 250°C and a pressure of 50 hPa, and the esterification reaction rate was 95. % reaction product was obtained.
A slurry consisting of isophthalic acid (IPA) and ethylene glycol was placed in another esterification reactor, and an esterification reaction was carried out at a temperature of 200° C. for 3 hours to obtain a reaction solution of isophthalic acid and ethylene glycol.
A reaction product of TPA and EG, a reaction solution of isophthalic acid and ethylene glycol, and a polymerization catalyst were added, and the pressure of the reactor was reduced to perform a melt polymerization reaction, resulting in a copolymerized polyester resin (8 mol% of IPA was copolymerized as an acid component). A substance having a melting point of 234°C and a melt viscosity of 1340 dPa·s ^-1 was obtained. A core forming composition containing only the copolymerized polyester resin was obtained.
(2) Manufacture of sheath forming composition Conductive carbon black is kneaded into PBT so that its content is 25% by mass, and a sheath forming composition having a melting point of 223°C and a melt viscosity of 1450 dPa·s ^-1 is prepared. Obtained.
(3) Manufacture of conductive composite fibers Prepare the above-mentioned core forming composition and sheath forming composition, supply them to a composite spinning device, and spin a spinneret designed so that the cross-sectional shape of the fiber becomes as shown in Figure 1. Melt spinning was performed using At this time, the core and sheath were arranged so that the area ratio (core/sheath) was 85/15, and the sheath covered the entire surface of the core. Furthermore, the melt viscosity difference between the core forming composition and the sheath forming composition at a spinning temperature of 270°C and a shear rate of 1000 s ^-1 (melt viscosity of the sheath forming composition - melt viscosity of the core forming composition) The viscosity) was 110 dPa·s ⁻¹ . Cooling air (28°C, wind speed 0.4 m/s) is blown onto the melt-spun yarn from the spinneret nozzle at a position 120 mm downward from the bottom surface of the spinneret nozzle for cooling, convergence, and oiling. A partially undrawn yarn was obtained. A 140°C heater plate was installed between the first roller (temperature 90°C) and the second roller (room temperature), and the partially undrawn yarn obtained was heat-treated between the first roller and the second roller. , Stretching was performed at a stretching ratio of 1.7 times, and the conductive composite fiber (28 dtex/6f) was wound up.
(4) Manufacture of conductive fabric Next, the obtained conductive composite fiber (28 dtex/6f) was covered with a polyester filament (manufactured by Unitika Trading Co., Ltd., 167 dtex/48 f) at 520 T/M in the Z direction to form a conductive fabric for the warp. A fiber covering yarn was obtained.
Further, the obtained conductive composite fiber (28 dtex/6f) was covered with a polyester filament (manufactured by Unitika Trading Co., Ltd., 340 dtex/96 f) at 400 T/M in the Z direction to obtain a conductive fiber covering yarn for weft.
As the warp arranged on the front side of the fabric, the arrangement of polyester filament (manufactured by Unitika Trading Co., Ltd., 167 dtex/48f) and the aforementioned conductive fiber covering yarn for warp is 15:1 (conductive fiber for warp in 16 warps). Polyester filaments (manufactured by Unitika Trading Co., Ltd., 95 dtex/48f) are prepared as warp threads on the back side of the fabric, and the warp threads on the front side and the warp threads on the back side are arranged so that the number of covering threads is 1. A beam was prepared by arranging the warp yarns in a ratio of 4:1 and warping them.
The prepared beam was set on a rapier loom, and the weft was driven in so that the arrangement of the polyester filament (manufactured by Unitika Trading Co., Ltd., 340 dtex/96f) and the conductive fiber covering yarn for the weft was 11:1, as shown in Figure 2. Weaving was carried out using the warp double plain weave structure shown, and a conductive woven fabric was obtained.
The obtained greige is scoured and dyed in a conventional manner, heat-set so that the conductive fiber covering threads are arranged at 5 mm intervals in both the warp and weft directions of the fabric, and the warp A conductive fabric (double fabric) having a density of 84 threads/2.54 cm and a weft density of 56 threads/2.54 cm was obtained.

Examples 2 to 6, Comparative Example 1
Melt spinning and drawing were carried out in the same manner as in Example 1, except that the melt viscosities of the core forming composition and the sheath forming composition were changed to those shown in Table 1, and conductive composite fibers of 28 dtex/6f were obtained. Obtained.
A conductive fabric was obtained in the same manner as in Example 1 using the obtained conductive composite fiber.

Examples 7-8, Comparative Examples 14-15
Melt spinning and drawing were performed in the same manner as in Example 1, except that the amount of conductive carbon black contained in the sheath forming composition was changed to that shown in Table 1, and conductive conjugate fibers of 28 dtex/6f were obtained. I got it.
A conductive fabric was obtained in the same manner as in Example 1 using the obtained conductive composite fiber.

Examples 9-10, Comparative Examples 2-3
Melt spinning and drawing were performed in the same manner as in Example 1, except that the blowing position of the cooling air in step (1) was changed to that shown in Table 1, to obtain a conductive composite fiber of 28 dtex/6 f.
A conductive fabric was obtained in the same manner as in Example 1 using the obtained conductive composite fiber.

Examples 11-12, Comparative Examples 4-5
Melt spinning and drawing were performed in the same manner as in Example 1, except that the winding speed in step (2) was changed to that shown in Table 1, to obtain a conductive conjugate fiber of 28 dtex/6 f.
In addition, in Comparative Example 5, it was not possible to obtain a conductive composite fiber because thread breakage occurred during stretching.
A conductive fabric was obtained in the same manner as in Example 1 using the obtained conductive composite fiber.

Examples 13-14, Comparative Examples 6-7
Melt spinning and drawing were performed in the same manner as in Example 1, except that the drawing temperature in step (3) was changed to that shown in Table 1, to obtain a conductive composite fiber of 28 dtex/6f.
A conductive fabric was obtained in the same manner as in Example 1 using the obtained conductive composite fiber.

Examples 15-16, Comparative Examples 8-9
Melt spinning and stretching were performed in the same manner as in Example 1, except that the stretching ratio in step (3) was changed to that shown in Table 1, to obtain a conductive composite fiber of 28 dtex/6f.
In Comparative Example 9, it was not possible to obtain conductive composite fibers because thread breakage occurred during stretching.
A conductive fabric was obtained in the same manner as in Example 1 using the obtained conductive composite fiber.

Examples 17-18, Comparative Examples 10-11
Melt spinning and drawing were performed in the same manner as in Example 1, except that the heat treatment temperature in step (4) was changed to that shown in Table 1, to obtain a conductive conjugate fiber of 28 dtex/6f.
A conductive fabric was obtained in the same manner as in Example 1 using the obtained conductive composite fiber.

Examples 19-20, Comparative Example 12
Example except that the amount of copolymerized isophthalic acid in the copolymerized polyester resin contained in the core forming composition was changed to that shown in Table 1, and the spinning temperature and melt viscosity difference were changed to those shown in Table 1. Melt spinning and drawing were performed in the same manner as in 1 to obtain a conductive composite fiber of 28 dtex/6f.
A conductive fabric was obtained in the same manner as in Example 1 using the obtained conductive composite fiber.

Examples 21-22, Comparative Example 16
Melt spinning and drawing were performed in the same manner as in Example 1, except that the area ratio between the core and sheath was changed to that shown in Table 1, to obtain a conductive conjugate fiber of 28 dtex/6f.
A conductive fabric was obtained in the same manner as in Example 1 using the obtained conductive composite fiber.

Comparative example 13
In the production of the sheath forming composition of Example 1, polyethylene terephthalate (PET) was used instead of PBT, conductive carbon black was kneaded into the PET so that the content was 25% by mass, and the melting point was 255 ° C. A sheath forming composition having a melt viscosity of 1980 dPa·s ⁻¹ was obtained.
Using the above sheath forming composition, melt spinning and stretching were carried out in the same manner as in Example 1, except that the spinning temperature and melt viscosity difference were changed to those shown in Table 1. Obtained fiber.
A conductive fabric was obtained in the same manner as in Example 1 using the obtained conductive composite fiber.

Table 1 shows the conditions in the manufacturing process of the conductive conjugate fibers in Examples 1 to 22 and Comparative Examples 1 to 16, and Table 2 shows the physical property values and evaluation results of the obtained conductive conjugate fibers and conductive fabrics.

As is clear from Tables 1 and 2, in Examples 1 to 22, conductive composite fibers could be obtained with good operability. Furthermore, the obtained conductive composite fibers satisfied the breaking strength, crystallinity, and initial electrical resistance values specified in the present invention, and had excellent durability in conductive performance.
The fabric using the obtained conductive composite fibers had low surface leakage resistance values in the vertical direction, horizontal direction, and between seams both at the initial stage and after washing 100 times. It had excellent durability.

On the other hand, in Comparative Examples 1 to 11, conductive composite fibers were manufactured using a manufacturing method that did not satisfy at least one of the conditions of steps (1) to (4). It was not possible to obtain a conductive composite fiber that satisfied all of the initial electrical resistance values.
For this reason, woven fabrics using these conductive composite fibers have poor conductivity and durability of conductivity.

In Comparative Examples 12 to 16, at least one of the type of polyester resin that is the resin component of the core or sheath, the content of the conductive component in the sheath forming composition, and the area ratio of the core and sheath is Since it did not satisfy the numerical range defined by the present invention, it was not possible to obtain a conductive composite fiber that satisfied all of the breaking strength, crystallinity, and initial electrical resistance value defined by the present invention.
For this reason, woven fabrics using these conductive composite fibers have poor conductivity and durability of conductivity.

1 Sheath part 2 Core part

Claims (4)

A core-sheath type polyester composite fiber consisting of a core part and a sheath part,
The core is composed of a core-forming composition mainly containing a polyester resin whose main repeating unit is ethylene terephthalate and which contains 1 to 15 mol% of isophthalic acid per 100 mol% of the acid component,
The sheath is composed of a sheath-forming composition that mainly contains polybutylene terephthalate and contains 20 to 35% by mass of a conductive component,
The area ratio of the core part and the sheath part (core part/sheath part) in a cross section perpendicular to the longitudinal direction of the yarn is 60/40 to 90/10,
A core-sheath type polyester composite fiber that satisfies all of the physical properties of (a) to (c) below.
(a) The breaking strength of the composite fiber is 3.0 cN/dtex or more (b) The degree of crystallinity of the composite fiber is 27 to 37%
(c) The initial electrical resistance value of the composite fiber is 5.0×10 ⁸ Ω/cm or less The core-sheath type polyester composite fiber according to claim 1, which further satisfies the following physical property (d).
(d) Electrical resistance value after 100 washes is 1.0×10 ⁹ Ω/cm or less A woven or knitted fabric comprising the core-sheath type polyester composite fiber according to claim 1 or 2. 3. The method for producing a core-sheath type polyester composite fiber according to claim 1 or ² , wherein the difference in melt viscosity between the core forming composition and the sheath forming composition (the The melt viscosity of the sheath forming composition - the melt viscosity of the core forming composition) was adjusted to 300 dPa·s ^-1 or less (absolute value), and the core forming composition and the sheath forming composition were placed in a composite spinning device. A method for producing a core-sheath type polyester composite fiber, characterized by supplying a material, performing melt spinning, and sequentially performing the following steps (1) to (4).
Step (1): Step (2) of cooling the undrawn yarn melt-spun from the spinneret nozzle by blowing cooling air at a position 100 to 150 mm downward from the bottom surface of the spinneret nozzle. : Step of winding the cooled undrawn yarn at 2000 to 3000 m/min (3): Step of stretching the wound undrawn yarn 1.2 to 2.0 times while heating it at 50 to 100°C. (4): After heat treating the drawn yarn at 130 to 150°C, wind it up.

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