JP7280295B2 - Multilayer structure spun yarn, manufacturing method thereof, heat-resistant fabric and heat-resistant protective clothing - Google Patents

Description

TECHNICAL FIELD The present invention relates to a multi-layered spun yarn containing stretch-breaking spun yarn of heat-resistant fibers as a core component fiber and heat-resistant short fibers as a sheath component fiber, a method for producing the same, a heat-resistant fabric, and a heat-resistant protective clothing.

Protective clothing is used as work clothing for firefighters, paramedics, lifeguards, marine rescuers, the military, petroleum-related facility workers, chemical factory workers, and the like. Firefighting uniforms in the United States, Canada, Australia, and some European countries in recent years use polybenzimidazole fibers, which are excellent in heat resistance and flame retardancy. Since this fiber has a weak strength of about 2.4 cN/decitex (decitex is abbreviated as dtex hereinafter), a fabric woven with p-aramid fiber is usually used. This woven fabric is composed of spun yarns of polybenzimidazole fibers as one of warp yarns and weft yarns, and filament yarns as p-aramid fibers as the other yarn. As another excellent heat-resistant and flame-retardant fabric, the present inventors use p-aramid fiber stretch-breaking spun yarn for the core and m-aramid fiber, flame-retardant acrylic fiber or polyetherimide fiber for the sheath. (Patent Documents 1 and 2). In Patent Document 3, the present inventors use p-aramid fiber stretch-breaking spun yarn for the core, and use a blended fiber of a flame-retardant fiber other than p-aramid fiber and polybenzimidazole fiber for the sheath. Patent Document 4 proposes a multi-layered spun yarn that uses p-aramid fiber stretch-breaking spun yarn for the core and a multi-layered spun yarn that uses a blended fiber of p-aramid fiber and polybenzimidazole fiber for the sheath. is proposing.

WO2009/014007 WO2012/137556 Japanese Patent No. 5972420 Japanese Patent No. 6599496

However, all of the above-mentioned prior arts have problems with friction strength, combustion burst strength, and discoloration from washing.

In order to solve the above conventional problems, the present invention provides a multi-layered spun yarn with improved friction strength, combustion burst strength and washing friction discoloration, a method for producing the same, a heat-resistant fabric and a heat-resistant protective clothing.

The multi-layered structure spun yarn of the present invention is a multi-layered structure spun yarn in which the core component fiber is p-aramid fiber stretch-breaking yarn, the sheath component fiber is polybenzimidazole fiber and aramid fiber, and the sheath component fiber is aramid The fiber contains p-aramid fiber and m-aramid fiber, and when the sheath component fiber is 100% by mass, polybenzimidazole fiber is 50 to 65% by mass, p-aramid fiber is 18 to 35% by mass, m- Aramid fibers are blended at a ratio of 3 to 18% by mass, some of the fibers of the sheath component fibers are fibers wound on the surface layer, and the remaining fibers are arranged in the length direction of the multilayer structure spun yarn. and the wound fibers of the surface layer are twisted in one direction to form a real twist, and the whole is bundled .

The method for producing a multi-layered structure spun yarn of the present invention is the above-described method for producing a multi-layered structure spun yarn, wherein a sliver of a heat-resistant staple fiber that will be a sheath component fiber is supplied to a draft zone and drafted. A stretch-breaking spun yarn of heat-resistant fibers to be a core component fiber is supplied to the front roller, combined with the drafted short fiber bundle, and combined with the spindle arranged away from the discharge part of the front roller. It is characterized by supplying a stretch-breaking spun yarn and a drafted staple fiber bundle, applying a false twist by a swirling flow, and then winding it.

The heat-resistant fabric of the present invention is characterized by using the multilayer structure spun yarn. Further, the heat-resistant protective clothing of the present invention is characterized by including the heat-resistant fabric.

By optimizing the composition of the heat-resistant fiber, the multi-layered spun yarn of the present invention is a multi-layered spun yarn that has acceptable levels of friction strength, combustion burst strength, and discoloration due to washing friction, a method for producing the same, heat resistance Fabric and heat resistant protective clothing can be provided. Since the manufacturing method of the multi-layered spun yarn of the present invention is a tie spinning method, it can be spun at a speed about 20 times higher than that of the ring spinning method, and can be manufactured efficiently and rationally at a low cost.

FIG. 1 is a schematic perspective view showing the main part of a binding spinning device for producing core-sheath structure spun yarn in one embodiment of the present invention. FIG. 2 is a schematic perspective view of a core-sheath structure spun yarn in one embodiment of the present invention. FIG. 3 is a side view photograph (magnification: 200) of the core-sheath structure spun yarn in one embodiment of the present invention. FIG. 4 is a side view photograph (magnification: 200) of a core-sheath structure spun yarn in another embodiment of the present invention. FIG. 5 is a weave diagram of a woven fabric in one embodiment of the present invention. FIG. 6 is a weave diagram of a fabric according to another embodiment of the present invention. FIG. 7 is a schematic perspective view of a wear testing device according to one embodiment of the present invention. FIG. 8 is a schematic cross-sectional view of a combustion rupture device according to JIS L 1096 B method.

The multi-layered spun yarn of the present invention is a multi-layered spun yarn in which the core component fiber is p-aramid fiber stretch-breaking yarn and the sheath component fiber is polybenzimidazole fiber and aramid fiber. The aramid fiber of the sheath component fiber contains p-aramid fiber and m-aramid fiber, and when the sheath component fiber is 100% by mass, polybenzimidazole fiber (hereinafter also referred to as "PBI") is 50 to 65% by mass. , 18 to 35% by mass of p-aramid fiber and 3 to 18% by mass of m-aramid fiber. As a result, the friction strength, combustion burst strength, and discoloration due to friction with washing are all at acceptable levels.
The multi-layered spun yarn of the present invention may be a spun yarn with a tie or a spun yarn with a ring tie, but a spun yarn with a tie is preferred because of its excellent productivity. In the case of the bundled spun yarn, the surface of the core component fiber is covered with the sheath component fiber, some of the sheath component fibers are the fibers wound on the surface layer, and the remaining fibers are the length of the multilayer structure spun yarn. The fibers are arranged in a direction, and the wound fibers on the surface layer are in a real twist shape in which the fibers are twisted in one direction, and the whole is bundled. In the case of the ring-spun yarn, the surface of the core component fiber is covered with the sheath component fiber and the yarn is actually twisted. Due to this structure, the yarn has high strength, low elongation, and high heat resistance.

When the multi-layer structure spun yarn is 100% by mass, the core component fiber is preferably 20 to 40% by mass, and the sheath component fiber is preferably 60 to 80% by mass. Furthermore, when the sheath component fiber is 100% by mass, PBI fiber is 50 to 65% by mass, p-aramid fiber is 18 to 35% by mass, and m-aramid fiber is a blended fiber of 3 to 18% by mass. preferable. As a result, the friction strength, combustion burst strength, and discoloration due to friction with washing are all at acceptable levels.

PBI fibers are fibers made from polymers such as 2,2'-(m-phenylen)-5,5'-bibenzimidazole, which have a thermal decomposition temperature of over 600°C, a deflection temperature under load of 410°C, and a glass transition temperature of 410°C. The point is 427° C. and the oxygen index (OI) value is 41 or more. This fiber has a strength retention rate of 95% even when exposed to air at 230°C for 2 weeks, and can maintain fiber performance up to 1000°C in nitrogen. Textile Encyclopedia" p.848, Maruzen, March 25, 2002). PBI fibers are known as products manufactured by PBI Performance Products, Inc., USA.

The copolymer-based p-aramid fiber used for the core component fiber is manufactured by Teijin Ltd. under the trade name of "Technora". The "Technora" is copolyparaphenylene-3,4'-oxydiphenylene-terephthalamide. These fibers have a tensile strength of 24.5-24.7 cN/dtex, a thermal decomposition onset temperature of about 500° C., and an oxygen index (OI) value of 25.

The m-aramid fiber used for the sheath component fiber is, for example, manufactured by Du Pont in the United States under the trade name "Nomex"s (the same trade name is manufactured by Toray Du Pont in Japan), manufactured by Teijin under the trade name "Conex", Made in China by Yantai Taiwa Co., Ltd., with the product name “New Star”. The product name "Nomex" has a tensile strength of 3.6 cN/decitex, a thermal decomposition initiation temperature of about 400°C, and an oxygen index (OI) value of 29-30.

The p-aramid fiber used for the sheath component fiber is a homopolymer system manufactured by Du Pont in the United States under the trade name "Kevlar" (same trade name as manufactured by Toray Du Pont in Japan), and manufactured by Teijin under the trade name "Twaron". registered trademark)”, and the product name “Taparan” manufactured by Taiwa Yantai.

Copolymer p-aramid fibers are available from Teijin under the trade name of "Technora". These fibers have a tensile strength of 20.3-24.7 cN/decitex, a thermal decomposition initiation temperature of about 500-550° C., and an oxygen index (OI) value of 25-29. Its heat resistance and flame resistance are higher than those of ordinary fibers.

It is preferable that the core component fiber is a stretch-broken spun yarn of a copolymer p-aramid fiber, and the p-aramid fiber of the sheath component fiber is a homopolymer p-aramid fiber. Copolymer para-aramid has excellent strength, so it is used in the core to increase the strength of the yarn, and homopolymer para-aramid has excellent flame resistance, so it is used in the sheath to prevent the yarn from burning. I'm letting

In multi-layered spun yarn, some fibers of the sheath component fiber are wound fibers on the surface layer, and the wound fibers on the surface layer are twisted in one direction, and the whole is bundled. be. Here, the whole means fibers other than the stretch-break spun yarn of the core component fiber and the wound fiber of the sheath component fiber.

When the multilayer structure spun yarn is 100% by mass, the core component fiber is preferably 20 to 40% by mass, and the sheath component fiber is preferably 60 to 80% by mass, more preferably 22 to 38% by mass. , the sheath component fiber is 62 to 78% by mass. If the content of the core component fiber is less than 20% by mass, the stretch-break spun yarn of the core component fiber must be made very fine, and it is difficult to produce the stretch-break spun yarn. On the other hand, when the core component fiber exceeds 40% by mass, the covering property of the sheath component fiber becomes low. If the sheath component fiber content is less than 60% by mass, good coverage is not obtained, and if it exceeds 80% by mass, the overall fineness of the multi-layered structure spun yarn increases, which is undesirable.

The copolymer-based p-aramid fiber stretch-cut spun yarn of the core component fiber is preferably a tow-broken cut spun yarn. Since the tow-broken strain-breaking fiber is a torn fiber, it becomes a multi-layered spun yarn with good affinity between the core component fiber and the sheath component fiber and good integration. This stretch-break spun yarn may be a direct spinning method in which draft-twisting is performed with one spinning machine, or it may be made into a sliver and twisted and then spun in two or more processes (Perlock method or converter method). good. Direct spinning is preferred. By using the stretch-breaking spun yarn, it is possible to obtain a core-sheath structure spun yarn that can maintain a high strength and is excellent in integration with the sheath fiber.

The preferred fineness of the stretch-breaking spun yarn is preferably in the range of 5.56 to 20.0 tex (50 to 180 metric single yarn), more preferably 6.67 to 16.7 tex (50 to 180 metric single yarn). in the range of 60 to 150 single yarns). If the fineness is within the above range, the strength is high, and it is suitable for heat-resistant protective clothing and the like in terms of texture and the like. The number of twists is preferably 350 to 550 twists/m, more preferably 400 to 500 twists/m, for a 125 metric count single yarn. If the number of twists is within the above range, the integrity with the coated fiber is further enhanced. Moreover, the preferred fiber length is distributed in the range of 30 to 180 mm, and the average fiber length is in the range of 45 to 150 mm, preferably 50 to 125 mm. Within this range, the strength can be maintained even higher.

The PBI fiber of the sheath component fiber is preferably a square cut product. Square cuts are repeated cuts of a certain length at right angles. For example, in the case of a 51 mm square cut, all fibers have a uniform length of 51 mm. The single fiber fineness is preferably in the range of 1-5 dtex, more preferably in the range of 1.5-4 dtex.

The sheath component fiber is processed into a staple fiber bundle of optimum shape and form by a spinning method according to its fineness and fiber length. Here, the hue and the mixing of different types of fibers can be achieved, for example, by passing a plurality of types of fiber bundles (sliver) each having a composition of 100% through a mixed hair intersecting gill box and doubling them in the subsequent comber or prespinning process. and by the drafting action parallel and symmetrical. This method is hereinafter referred to as "sliver blending". This method has a good yield and is suitable for high-mix low-volume production. Here, the blending of shades and different fibers is done mainly in the carding machine during the blending and carding process. This method is hereinafter referred to as "card blending", and although the yield is poor, it is suitable for mass production of a small variety of products.

The multi-layer structure spun yarn preferably has a metric count (single yarn) of 28 to 52 (fineness: 357 to 192 decitex). Within this range, protective clothing with good workability can be obtained. The multi-layered spun yarn is a two-ply yarn in which two yarns are twisted, and the metric count of the two-ply yarn may be 14 to 26 (fineness: 714 to 384 decitex). Two-ply yarn not only makes the surface of the fabric clean, but also increases the strength of the fabric.

The twist coefficient K of the two-ply yarn is preferably 100-200. However, the coefficient K is calculated by the following formula (1).
K=T/√C Expression (1)
T: Number of twists of two-ply yarn (twists/m)
C: Two-ply yarn count (m / g)

The heat-resistant protective clothing containing the heat-resistant fabric of the present invention is suitable for firefighting clothing, as well as work clothing for ambulance personnel, lifesaving personnel, marine rescue personnel, the military, petroleum-related facility workers, chemical factory workers, and the like. be. In the case of firefighting clothing, it is preferable to use the heat-resistant fabric of the present invention for the outer layer. It is because heat resistance is high.

Next, the apparatus and method for producing the core-sheath structure yarn of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing the main part of a binding spinning device 1 according to one embodiment of the present invention.
(1) Draft process The draft zone 6 of the binding spinning device 1 is composed of a pair of front rollers 2, 2', a pair of second rollers 3 having an apron, a pair of third rollers 4, and a pair of back rollers 5. ing. A sliver 7 made by blending polybenzimidazole fibers and aramid fibers, which are sheath component fibers, is passed through a sliver guide 8, supplied from a back roller 5, and drafted in a draft zone 6. - 特許庁
(2) Combining Core Component Fiber and Coating Component Fiber In front of the front rollers 2, 2′ of the draft zone 6, p-aramid fiber stretch-breaking spun yarn 9 serving as the core component fiber is supplied, and the sliver 7 is drafted. coalesce with the fiber bundle.
(3) Spun Yarn Forming Step Supply the united stretch-cut spun yarn 9 of the core component fiber and the fiber bundle of the sheath component fiber to the spindle 10 arranged away from the discharge part of the front rollers 2, 2', A multi-layered spun yarn 11 is obtained by false twisting with a swirling flow.
(4) Winding process The multi-layered spun yarn 11 obtained is taken up by nip rollers 12 and 12', passed through a slab catcher 13, driven by the friction rollers 14 of the winding section 17 and supported by the cradle arm 15. It is wound on the package 16 .
The spinning machine used in the manufacturing method of the present invention is sold under the trade name "MURATA VORTEX SPINNER" manufactured by Murata Machinery Co., Ltd., for example. A characteristic feature is that the yarn speed is 300 to 450 m/min, which is about 10 times faster than the ring spinning machine.

FIG. 2 shows a multi-layer structure spun yarn (bundle spun yarn) 20 as an example of the present invention. In FIG. 2, the core component fiber 21 is stretch-spun copolymer p-aramid fiber yarn, and the sheath component fiber 25 is a blended fiber of PBI fiber, homopolymer p-aramid fiber and m-aramid fiber. Sheath component fibers 25 include inner layer fibers 22 arranged in the longitudinal direction of the multilayer structure spun yarn, surface layer winding fibers 23, slack fibers 24, and fluff 26 is also recognized. The wound fibers 23 of the surface layer are in a real-twisted shape, twisted in one direction, and bundle the whole. As a result, there is little fluff, the fibers do not fall off even when worn, and a strong yarn state is maintained. In the above description, "one direction" refers to S-twisted fibers or Z-twisted fibers, and does not mean that the twist angles are the same. S-twist wound fibers or Z-twist wound fibers are determined by the direction of the pneumatic swirl flow of the spinner of the tie spinner. This multi-layer structure spun yarn (bundle spun yarn) 20 consists of a core component fiber (stretch-breaking spun yarn) 21, inner layer fibers 22 arranged in the length direction among sheath component fibers 25, and wound fibers 23 on the surface layer. It has a three-layer structure. Due to this yarn structure, the yarn strength is high.

FIG. 3 is a side view photograph (magnification of 200 times) of the core-sheath structure spun yarn in one embodiment of the present invention, and FIG. 4 is a side view view (magnification of 200 times) of the core-sheath structure spun yarn in another embodiment of the present invention. . In each case, there are inner layer fibers arranged in the length direction of the sheath component fibers, surface layer winding fibers, and slack fibers, and fluff is also observed.

The fabric for protective clothing of the present invention is preferably made by twisting two of the above-mentioned core-sheath spun yarns (single yarns) to form a two-ply yarn, which is then made into a woven fabric. The reason for using two-ply yarn is that it is more than twice as strong as a single yarn, giving it a cohesive force that prevents yarn breakage during weaving, and also offsets the uneven thickness of the single yarn, creating a beautiful weave. It is for Two-ply yarn is manufactured using a twister such as a double twister, for example. The double twister is highly productive because it can twist twice with one rotation of the spindle. However, since there are as many as six rubbing points on the long twisting yarn path, the covering tends to be peeled off and disturbed to expose the core. A ring twister with two rubbing points is preferred, and an up-twister with two rubbing points and a very short twisted yarn path is most preferred.

The obtained two-ply yarn is twisted and used as warp and weft to form a woven fabric. As the woven fabric, a plain weave, a twill weave, a satin weave, or other variation weave can be used. When knitted, any of flat knitting, circular knitting and warp knitting can be applied. Any knitting structure may be used. When the knitted fabric contains air, it is knitted into a double-knotted pile fabric. The mat weave shown in FIG. 5 is preferred among the weaves, and this mat weave is a plain +3/3 mat weave. The plain weave part is composed of eight warp and weft yarns and has a plain texture, while the 3/3 mat weave part has three warps and three wefts aligned, and this part protrudes to the surface. Another example of mat weave is shown in FIG. This mat weave structure is a plain +2/2 mat weave. The plain weave portion is composed of two warp and weft yarns and has a plain weave, while the 2/2 mat weave portion has both warp and weft yarns aligned, and this portion protrudes to the surface. Such a woven fabric has an anti-slip effect, and even if the plain weave is torn, it stops at the mat woven portion and is resistant to tearing. This is called a Rip Stop structure in the sense that it prevents tearing.

The weight per unit (basis weight) of the protective clothing fabric of the present invention is preferably in the range of 100 to 340 g/m ² . Within the above range, work clothes that are lighter and more comfortable to wear can be obtained. It is more preferably in the range of 140-300 g/m ² , particularly preferably in the range of 150-260 g/m ² .

The multi-layered spun yarn of the present invention and the heat-resistant fabric and heat-resistant protective clothing using the same do not necessarily contain antistatic fibers or antistatic fibers. This is because PBI fibers easily absorb moisture and are less likely to be charged with static electricity. When antistatic fibers are mixed according to the customer's request, metal fibers, carbon fibers, fibers kneaded with metal particles or carbon particles, etc. are used. The antistatic fiber is preferably added in the range of 0.1 to 1% by mass, more preferably in the range of 0.3 to 0.7% by mass, based on the spun yarn. Antistatic fiber yarns can also be added during weaving. For example, it is preferable to add 0.1 to 1% by mass of "Beltron" manufactured by KB Seiren, "Kuracarbo" manufactured by Kuraray, carbon fiber, metal fiber, or the like.

A more specific description will be given below using examples. The invention is not limited to the following examples.
The measurement methods in the examples and comparative examples of the present invention were as follows.
<Abrasion test>
FIG. 7 is a schematic perspective view of a wear test apparatus 30 specified in ASTM D 3884-09 Taber method, H-18, according to one embodiment of the present invention. In this abrasion tester 30, a sample cloth 32 is placed on a turntable 31 and rotated as indicated by an arrow. The rotational speed of the turntable 31 is 60 rpm, and the friction wheels 33a and 33b also rotate accordingly. Friction wheels 33a and 33b are arranged on the sample cloth 32 and are rotated in opposite directions as indicated by arrows. The total load of the friction wheels 33a and 33b is 500g. Abrasion powder continues to rotate while being sucked. The wear scar 34 is annular, with an outer diameter L1 of about 88 mm and an area of about 30 cm ² . Measure the number of rotations until the thread is cut and a hole with a diameter of 1 to 2 mm is opened. 300 times or more is regarded as a passing level.
<Combustion burst test applying JIS L 1096 B method>
FIG. 8 is a schematic cross-sectional view of a constant-velocity extensional combustion-bursting device 35 according to the JIS L 1096 B method. A sample cloth 37 with a diameter of 80 mm is attached to the clamp of the sample mount 36 . The clamp has an inner diameter L2=44 mm. The push rod 38 has a tip radius of 12.5 mm and a diameter L3 of 25 mm. After irradiating the sample cloth with 80 kW of heat for 8 seconds in the flame exposure test of ISO 9151, the tip of the push rod 38 is pressed against the burned portion at a pressure rate of 10 cm per minute, and the strength to break through the sample cloth 37 (N) is measured. 140N or more is taken as a pass level.
<Washing abrasion discoloration test>
Washing was repeated 10 times by the method specified in ISO6330 6N-F, and evaluation was made. The evaluation criteria are five grades, and the least discoloration is grade 5, and the most discoloration is grade 1. Grade 3 or higher is considered a passing level.
<Other physical properties>
Measured according to JIS or industry standards.

(Examples 1-2, Comparative Examples 1-2)
1. Fibers used (1) Core component fiber As the core component fiber, copolymer p-aramid fiber, Teijin's product name "Technora" stretch-cut spun yarn (number of twists in Z direction 45 times / 10 cm), yarn fineness 8.0 tex (Metric count: 1/125) (single fiber fineness 1.7 dtex, average fiber length 100 mm, product (yellow)) was used.
(2) Sheath Component Fibers The following three types of fibers were blended.
(i) PBI fiber PBI fiber (square cut fiber length 51 mm, fineness 1.7 dtex) manufactured by PBI Performance Products, Inc., USA was used.
(ii) Homopolymer p-aramid fiber A trade name "Taparan" manufactured by Yantai Taiwa Co., Ltd. of China (square cut fiber length 51 mm, fineness 1.7 dtex, black) was used.
(iii) m-aramid fiber "New Star BL3" (square cut fiber length 51 mm, fineness 1.7 dtex) manufactured by Yantai Taiwa Co., Ltd. of China was used.
The above PBI fiber, homopolymer p-aramid fiber, and m-aramid fiber were uniformly mixed at a predetermined ratio shown in Table 1.
2. Preparation of spun yarn (1) Tie spun yarn By the method shown in FIG. The blended fiber bundle (sliver) is used as the sheath component fiber, and the product name "No.870, MURATA VORTEX SPINNER" manufactured by Murata Machinery Co., Ltd. shown in Fig. 1 is used to produce a single bundled spun yarn at a speed of 300 m / min. bottom. The metric count of the yarn obtained was #40.
(2) Preparation of two-ply yarn Using a double twister, two bundled spun yarn single yarns were actually twisted into a two-ply yarn. The number of twists was 670 times/m, and the twist coefficient was K=150.
3. Using the two-ply yarns as warps and wefts, a rapier loom was used to fabricate a woven fabric having a ^2/2 mat weave structure shown in FIG. , and a weft direction yarn density of 206.7 yarns/10 cm.
The conditions and results are summarized in Tables 1-2.

As is clear from Table 2, it was confirmed that Examples 1 and 2 were at acceptable levels in terms of friction strength, combustion burst strength, and discoloration due to washing.

Heat-resistant protective clothing using the heat-resistant fabric of the present invention is suitable not only for firefighting clothing, but also for work clothing such as rescue workers, rescue workers, marine rescue workers, the military, workers at petroleum-related facilities, and workers at chemical plants. is. In particular, it is possible to provide a heat-resistant fabric and a heat-resistant protective clothing that have acceptable levels of friction strength, combustion burst strength, and discoloration by washing.

1 Binding spinning device 2, 2' Front roller 3 Second roller 4 Third roller 5 Back roller 6 Draft zone 7 Sliver 8 Sliver guide 9 Stretch-break spun yarn 10 Spindle 11 Multi-layer structure spun yarn 12, 12' Nip roller 13 Slive catcher 14 Friction roller 15 cradle arm 16 package 20 multi-layer structure spun yarn (bonded spun yarn)
21 Core component fiber (stretch-cut spun yarn)
22 Inner layer fiber of sheath component fiber 23 Winding fiber 24 Sagging fiber 25 Sheath component fiber 26 Fluff 30 Abrasion test device 31 Rotating table 32 Sample cloth 33a, 33b Friction wheel 34 Abrasion mark

Claims (10)

The core component fiber is p-aramid fiber stretch-breaking yarn, and the sheath component fiber is a multi-layered spun yarn containing polybenzimidazole fiber and aramid fiber,
The aramid fibers of the sheath component fibers include p-aramid fibers and m-aramid fibers,
When the sheath component fiber is 100% by mass, the polybenzimidazole fiber is 50 to 65% by mass, the p-aramid fiber is 18 to 35% by mass, and the m-aramid fiber is blended at a ratio of 3 to 18% by mass. ,
Some of the fibers of the sheath component fibers are surface layer wound fibers, and the remaining fibers are arranged in the length direction of the multilayer structure spun yarn,
A multi -layered spun yarn, wherein the wound fibers of the surface layer are in a real-twisted form in which the fibers are twisted in one direction, and the whole is bundled . 2. The multilayer structure spun yarn according to claim 1 , wherein the core component fiber is a copolymer p-aramid fiber stretch-breaking yarn, and the sheath component p-aramid fiber is a homopolymer p-aramid fiber. The multilayer structure spun yarn according to claim 1 or 2 , wherein the core component fiber accounts for 20 to 40% by mass and the sheath component fiber accounts for 60 to 80% by mass, based on 100% by mass of the multilayer structure spun yarn. The multi-layer structure spun yarn according to any one of claims 1 to 3 , wherein the multi-layer structure spun yarn has a metric count of 28 to 52 (fineness: 357 to 192 decitex). The multilayer structure according to any one of claims 1 to 4 , wherein the multi-layer structure spun yarn is a two-ply yarn twisted together, and the metric count of the two-ply yarn is 14 to 26 (fineness: 714 to 384 decitex). Structural spun yarn. 6. The multi-layered spun yarn according to claim 5 , wherein the twist coefficient K of the two-ply yarn is 100-200.
However, the coefficient K is calculated by the following formula (1).
K=T/√C Expression (1)
T: Number of twists of two-ply yarn (twists/m)
C: Two-ply yarn count (m / g) A method for producing a multilayer structure spun yarn according to any one of claims 1 to 6 ,
A sliver that is a blend of polybenzimidazole fiber and aramid fiber, which is a sheath component fiber, is supplied to the draft zone and drafted,
Supplying a p-aramid fiber stretch-cutting yarn as a core component fiber to the front roller of the draft zone to form a fiber bundle united with the sliver,
A method for producing a multi-layered spun yarn, wherein the fiber bundle is supplied to a spindle arranged away from the discharge portion of the front roller, false twisted by a swirling flow, and then wound. A heat-resistant fabric comprising the multi-layered spun yarn according to any one of claims 1 to 6 . 9. The heat-resistant fabric according to claim 8 , wherein the heat-resistant fabric is a fabric in which a plain weave and a 2/2 or 3/3 mat weave are combined. A heat-resistant protective clothing comprising the heat-resistant fabric according to claim 8 or 9 .

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