TWI793386B - Polyamide multifilament and covered elastic yarn - Google Patents

Abstract

The object of the present invention is to provide a high-tenacity polyamide multifilament yarn that can obtain stockings that are excellent in durability as well as excellent in transparency and feel. The polyamide multifilament of the present invention has a total fineness of 6 to 20 dtex, a loop strength of more than 12 cN/dtex, and a flatness represented by the ratio (b/a) of the major diameter b to the minor diameter a of the single fiber cross section 1.5~5.0, the above-mentioned problems can be achieved by the polyamide multifilament.

Description

Polyamide multifilament and covered elastic yarn

The present invention relates to polyamide multifilament and covered elastic yarn suitable for stockings. More specifically, it relates to polyamide multifilament and covered elastic yarn that can provide silk stockings with excellent durability, high transparency, and good hand feeling when used in stockings.

Polyamide fibers and polyester fibers, which are synthetic fibers, are widely used in clothing and industrial applications because of their excellent mechanical and chemical properties. In particular, polyamide fiber has excellent characteristics such as unique softness, high strength, color development during dyeing, heat resistance, and hygroscopicity. Therefore, polyamide fibers are widely used in general clothing materials such as stockings, underwear, and sportswear.

The consumer demand for stockings is to expect high transparency and soft touch stockings, and there have been many proposals for improvement technologies. For example, the proposals of Patent Document 1 include: a flatness of 1.5 to 5.0, and the cross-sectional shape of the fiber is symmetrical with respect to the long axis (Japanese ancient coins), polyamide multifilament in the shape of a convex lens, and stockings using the same.

Furthermore, Patent Document 2 proposes: a high-strength polyamide multifilament with a total fineness of 4.0 to 6.0 dtex and a tenacity product of 9.1 cN/dtex or more, and stockings using the same. In addition, as a production method for improving the tensile strength product of polyamide multifilament, it is proposed to adopt cooling conditions such as maintaining the ambient temperature under the spinneret at a high temperature to promote relaxation of polymer alignment and lower the solidification point.

[Prior Art Literature]

[Patent Document]

Patent Document 1: Japanese Patent Laid-Open No. 2009-203563

Patent Document 2: International Publication No. 2016/076184

However, Patent Document 1 discloses that the durability of stockings decreases as the denier becomes thinner. In addition, due to the flattened cross section, the flat minor axis becomes thinner than the diameter of the circular cross section, so there is a problem that the thread strength is lowered and the durability of stockings is lowered than that of the circular cross section.

Furthermore, even if the condition described in Patent Document 2 is to keep the ambient temperature under the spinneret at a high temperature in order to improve the elongation product to promote polymer alignment relaxation and reduce the solidification point to Patent Document 1, the The flatness decreases when the flat cross section is formed due to the lowering of the solidification point. In this case, the feel and aesthetics of the obtained silk stockings cannot be satisfied.

In addition, although the flat cross-section can achieve hand feeling and aesthetics, compared with the round cross-section, because the flat short axis is thinner than the round cross-section diameter, it is undeniable that the durability of stockings will be reduced, so it is expected to further improve the durability.

In order to solve the above-mentioned problems, the object of the present invention is to provide a flat polyamide multifilament yarn and a covered elastic yarn that are excellent in durability when used in stockings, and that are excellent in transparency, soft touch, and aesthetics.

In order to solve the above-mentioned problems, the present invention employs the following configurations.

(1) A polyamide multifilament, the total fineness is 6~20dtex, the loop strength is more than 12cN/dtex, expressed according to the ratio (b/a) of the long diameter b to the short diameter a of the single fiber cross section The flatness is 1.5~5.0.

(2) The polyamide multifilament as described in (1) above, wherein the tensile strength at 15% elongation is 5.0 cN/dtex or more.

(3) A covered elastic yarn in which the polyamide multifilament as described in (1) or (2) above is arranged as a covered yarn.

The polyamide multifilament of the present invention is a polyamide multifilament with high flatness and high loop strength. In addition, when the polyamide multifilament yarn and the covered elastic yarn of the present invention are used in stockings, it is possible to obtain stockings excellent in durability, transparency, soft touch, and aesthetics.

1: spinning nozzle

2: Gas supply device

3: Heating cylinder

4: cooling device

5: Oil supply device

6: Fluid rotary nozzle device

6a: Rotary nozzle

7: traction roller

8: The first stretching roller

9: The second stretching roller

10: relaxation roller

11:Interaction granting device

12: Coiling device

20: multifilament

a: short diameter

b: long diameter

D: Hole diameter

H: spit hole width

L: length of heating cylinder

LS: start cooling distance

Lg: oil supply position

LA: Rotary nozzle length

N: spit hole length

W: Swirl flow

Fig. 1 is a schematic diagram of an embodiment of a production apparatus that can be preferably used in the production method of the polyamide multifilament of the present invention.

Fig. 2 is a schematic diagram of an embodiment of a production apparatus used in a comparative example production method of the polyamide multifilament production method of the present invention.

Fig. 3 is a schematic cross-sectional view of a spinning nozzle and a heating cylinder that can be preferably used in the method for producing polyamide multifilament according to the present invention.

In Fig. 4, Fig. 4(a) and Fig. 4(b) are an embodiment of a rotary nozzle that can be preferably used in the manufacturing method of the polyamide multifilament of the present invention, and Fig. 4(a) is the whole of the rotary nozzle Schematic diagram, Fig. 4(b) is the AA' sectional view of Fig. 4(a).

Fig. 5 is a diagram of an embodiment of the shape of the discharge hole of a spinning nozzle that can be preferably used in the production method of the polyamide multifilament of the present invention.

Fig. 6 is a fiber sectional view of an embodiment of the polyamide multifilament of the present invention.

Hereinafter, the present invention will be described in more detail. In addition, in this specification, "mass" is synonymous with "weight".

[Polyamide Multifilament]

The polyamide constituting the polyamide multifilament according to the embodiment of the present invention is a resin composed of a high molecular weight body in which so-called hydrocarbon groups are linked via amide bonds in the main chain. Polyamide-based yarns are excellent in spinning properties and mechanical properties. The polyamide system can be exemplified: polycaproamide (nylon 6), polyhexamethylene adipamide (nylon 66), etc., from the point of view that it is not easy to gel and good silk-making property, the polyamide system is preferred. Caprylamide (Nylon 6).

Here, the above-mentioned polyamide-based unit components mainly constituting the polyamide may contain 80 mol% or more. Preferably, the above-mentioned polyamide contains more than 90 mol% of unit components. Among polycaplamides, ε-caprolactam, which mainly constitutes polycaplamide, is a unit component. In addition, in polyhexamethylene adipamide, adipammonium adipate mainly constituting polyhexamethylene adipamide is a unit component.

The other components contained in the above-mentioned polyamide are not particularly limited, and examples thereof include polydodecylamide, polyhexamethylene adipamide, polyhexamethylene azelamide, polyhexamethylene Methyl sebacamide, polyhexamethylene dodecyl amide, polymethylene adipamide, polyhexamethylene terephthalamide, polyhexamethylene isophthalamide Amino carboxylic acids, dicarboxylic acids, diamines, etc. of monomers such as amines.

Furthermore, in order to effectively exhibit the effect of the present invention, it is preferable to contain various additives such as a matting agent represented by titanium oxide in the polyamide, and a heat-resistant agent may also be contained if necessary within the range that does not hinder the effect of the present invention. and other additives. Moreover, its content is preferably between 0.001 to 0.1% by weight relative to the polymer (polyamide).

The polyamide multifilament system according to the embodiment of the present invention has a total fineness of 6 to 20 dtex, a loop strength of 12 cN/dtex or more, and a ratio of the major diameter b to the minor diameter a of the single fiber cross section (b/a, hereinafter referred to as "flatness") )1.5~5.0. By reducing the total fineness of the polyamide multifilament and increasing the flatness, stockings with high transparency and soft touch can be obtained. On the other hand, the polyamide multifilament with reduced total fineness and increased flatness has a smaller diameter of the flat minor axis than the circular section, so the yarn strength is lower than that of the circular section, and the durability when used in stockings is reduced. Here, in terms of the structure of stockings, the stress applied to the intersecting portion of the loop points of the knitting needle loops and the sinker loops becomes large, so the durability of stockings can be evaluated by the loop strength. Therefore, after intensive research, it was found that in order to provide stockings that are excellent in transparency, texture, and durability, the total fineness, loop strength, and flatness should be set within this range.

The total fineness of the polyamide multifilament system according to the embodiment of the present invention is 6-20 dtex. By setting the total fineness within this range, stockings with high transparency and soft texture can be obtained. When the total fineness is below 20dtex, the transparency and hand feel of the stockings are improved. When the total fineness reaches above 6dtex, the durability of stockings is improved. The better total fineness is 6~11dtex.

The loop strength of the polyamide multifilament system according to the embodiment of the present invention is above 12 cN/dtex. By setting the loop strength within this range, the durability of stockings can be improved, and flattening can also be performed to improve transparency and texture. The durability, transparency, and aesthetics of stockings can be improved by the loop strength reaching over 12cN/dtex. Also, the greater the loop strength, the better, but the upper limit in the present invention is about 17 cN/dtex. The ring strength is preferably above 13cN/dtex. In addition, the loop strength was measured based on "8.7 loop strength" of JIS L1013 (2010).

Most of the breakage of stockings occurs when they are stretched from the toes to the thighs. At this time, in stockings knitted fabrics, if the degree of thinness and flatness of the polyamide multifilament are higher, the filament will be less able to withstand the stress imposed on the loop point of the knitting needle loop and the sinker loop. Combined with stress, the filament is more likely to break. Therefore, it was found that not only the strength in the fiber axis direction (tensile strength), but also the improvement of the loop strength is an important matter for improving the durability of stockings. That is, in addition to the strength in the fiber axis direction (tensile strength) of the conventional polyamide filament, by increasing the strength of the stress concentration part (loop strength) at the loop point of the knitting needle loop and the sinker loop , can also improve the durability of stockings.

The polyamide multifilament according to the embodiment of the present invention has a flat fiber cross-section with a flatness of 1.5 to 5.0 represented by the ratio (b/a) of the major diameter b to the minor diameter a. By setting the flatness within this range, it is possible to obtain stockings with improved fiber bending flexibility and excellent hand feeling. Moreover, since the bending softness is high, the covering property of the covered yarn becomes uniform, and stockings excellent in both transparency and aesthetics can be obtained. When the flatness reaches above 1.5, the hand feeling, transparency and aesthetics of the stockings are improved. When the flatness is 5.0 or less, the texture, transparency, and aesthetics are all excellent, and the aligned crystallization of the polymer (polyamide) is not too low, so that the durability of the stockings is sufficient. The preferred flatness is 2.5~4.0. Fig. 6 shows an embodiment of the fiber cross section of the polyamide multifilament according to the embodiment of the present invention.

In addition, the cross-sectional shape of the polyamide multifilament according to the embodiment of the present invention is not particularly limited as long as it is flat, and the surface shape is not particularly limited. For example, the polyamide multifilament of the embodiment of the present invention can also be, for example, a lens-shaped cross section, a bean-shaped cross-section, and a special-shaped cross-section with 3-8 convex parts and the same number of concave parts.

The polyamide multifilament according to the embodiment of the present invention is preferably one of the physical properties of the original yarn, the tensile strength at 15% elongation (hereinafter referred to as "15% strength"), which is above 5.0 cN/dtex. 15% strength is measured in accordance with "8.5 Tensile strength and elongation" of JIS L1013 (2010). A tensile strength-elongation curve is drawn, and the value obtained by dividing the tensile strength (cN) at 15% elongation by the fineness is taken as 15% strength. The 15% strength is simply the value of the fiber modulus, the higher the 15% strength, the higher the slope of the tensile strength-elongation curve, A higher fiber modulus, on the other hand, a lower 15% strength, indicates a lower slope of the tensile strength-elongation curve and a lower fiber modulus.

Although it will be described in detail later, the polyamide multifilament system according to the embodiment of the present invention can realize high fiber modulus without fluff by performing multi-stage and high-magnification drawing. By setting the 15% intensity within this range, the cloth surface circles in the covering step can be stabilized without loosening, and the covering property can be made uniform. That is, by obtaining a covered yarn excellent in uniform covering properties, it is possible to obtain stockings excellent in transparency, beautiful in weaving texture, and excellent in aesthetics. 15% strength is better at 5.5~6.5cN/dtex.

The polyamide multifilament according to the embodiment of the present invention preferably has a tensile strength of 6.5 cN/dtex or higher. If the tensile strength is above 6.5 cN/dtex, the alignment and crystallization of the polymer (polyamide) can be improved, and the ring strength can be improved. The better tensile strength is 6.8~7.3cN/dtex.

[Manufacturing method of polyamide multifilament]

Next, an example of the method for producing polyamide multifilament according to the embodiment of the present invention will be specifically described. Fig. 1 is a schematic diagram of an embodiment of a manufacturing apparatus preferably used in a method for manufacturing polyamide multifilament according to an embodiment of the present invention.

When producing the polyamide multifilament according to the embodiment of the present invention, the polyamide polymer is first melted, metered and conveyed by a gear pump, and finally extruded from the discharge hole provided in the spinning nozzle 1 to form Each filament. In this way, the filaments discharged from the spinning nozzle 1 are passed through the gas supply device 2 for blowing off steam for suppressing fouling of the spinning nozzle over time as shown in FIG. 1 , and for gradually cooling. The heating cylinder 3 arranged around the whole circumference is cooled to room temperature and solidified by passing through the cooling device 4 . Then, the oil agent is applied to each filament by using the oil supply device 5, and at the same time, each filament is bundled to form a multifilament, and then Concentration is imparted by the fluid rotary nozzle device 6 . Then, the multifilament is stretched in two stages by the take-off roll 7 , the first draw roll 8 , and the second draw roll 9 , and then relaxed by the relaxation roll 10 . The relaxed multifilament yarn is entangled by the entanglement imparting device 11 and then wound by the take-up device 12 .

When manufacturing the polyamide multifilament according to the embodiment of the present invention, the sulfuric acid relative viscosity of the polyamide is preferably 2.5-4.0. When the sulfuric acid relative viscosity of polyamide is set within this range, polyamide multifilaments with high loop strength, 15% strength, and tensile strength can be obtained.

Furthermore, the melting temperature of polyamide is preferably 20°C higher than the polyamide melting point (Tm) (Tm+20°C) and lower than (Tm+95°C).

When producing the polyamide multifilament according to the embodiment of the present invention, in order to achieve the desired flatness and high strength, it is necessary to optimize the discharge holes of the spinneret 1 and set the discharge linear velocity to an appropriate value. Fig. 5 shows an embodiment of the hole shape of the discharge hole. By making the single-hole discharge area of the spinning spinneret 1 smaller, the discharge linear velocity of the polymer can be increased. Therefore, the stress between the spinneret surface and the pulling roll can be reduced, polymer alignment can be suppressed, the mechanical elongation ratio can be increased, and high strength can be easily realized. The discharge line speed is the value of the discharge volume divided by the discharge hole area, preferably 25~50m/min, more preferably 30~40m/min.

In conventional spinning spinnerets, in order to achieve the required flatness, it is necessary to elongate the discharge hole length N in the long diameter direction of the discharge hole (conventional technology). In this case, the discharge area of a single hole of the spinning spinneret 1 becomes large, and as a result, the discharge linear velocity of the polymer decreases, making it impossible to obtain a desired strength. On the other hand, by minimizing the discharge hole width H in the short diameter direction without elongating the discharge hole length N in the long diameter direction, the flatness can be greatly improved. According to this method, the discharge area of a single hole of the spinning spinneret 1 can be reduced while improving the flatness, and the required range of discharge linear speed can be adopted. result High strength of silk can be realized. The width H of the discharge hole is preferably 0.060-0.080 mm, more preferably 0.065-0.075 mm.

As for the cooling conditions of each filament, in order to achieve a high flatness, generally, conditions for raising the solidification point (quick cooling conditions) are set. In addition, in order to achieve high strength, generally, as described in Patent Document 2, the ambient temperature under the spinneret is maintained at a high temperature, etc., to promote relaxation of polymer alignment and lower the solidification point (gradual cooling conditions). That is, conventional knowledge is contradictory in terms of achieving high flatness and high strength at the same time as the polyamide multifilament of the present invention. Therefore, in the present invention, the dense temperature distribution was analyzed, and it was found that in order to achieve the required flatness and high strength, a gradual cooling zone that maintains the ambient temperature at a high temperature is provided under the spinneret, and the alignment of the polymer is sufficiently promoted. After that, the best manufacturing conditions for rapid solidification are carried out in the cooling area.

When producing the polyamide multifilament according to the embodiment of the present invention, as shown in FIG. 3 , a heating cylinder 3 is installed on the upper part of the cooling device 4 so as to surround each filament. By arranging the heating cylinder 3 on the upper part of the cooling device 4, and setting the ambient temperature in the heating cylinder 3 within the range of preferably 280~310°C, the temperature of the polyamide discharged from the spinning nozzle 1 can be increased. Alignment eases. By utilizing the gradual cooling region from the spinneret surface to the bottom of the heating cylinder to promote alignment relaxation, it is possible to achieve the required high strength such as hoop strength. If the heating cylinder 3 is not provided, the above-mentioned gradual cooling region does not exist, and the alignment relaxation from the spinneret surface to the cooling is insufficient, so it is difficult to achieve the required high strength such as hoop strength.

The length L of the heating cylinder varies according to the fineness of the multifilament, preferably 30~90mm. By setting the length L of the heating cylinder to 30 mm or more, it becomes a distance sufficient to promote relaxation of polymer alignment, and high strength can be easily achieved. Also, by setting the length L of the heating cylinder to 90 mm or less, desired flatness can be easily achieved. The length L of the heating cylinder is preferably 40~70mm.

Furthermore, the heating cylinder 3 is preferably multi-layered. In the fineness region like the polyamide multifilament of the embodiment of the present invention, if the temperature distribution in the heating cylinder 3 is constant, the heat convection tends to be in a messy state, which affects the solidification state of each filament, resulting in uneven filaments. (U%) causes of deterioration. Therefore, by setting the heating cylinder 3 into multiple layers, the set temperature is gradually lowered from the upper layer to the lower layer, thereby intentionally causing heat convection from the upper layer to the lower layer. Then, by setting the downdraft in the same direction as the yarn derivative flow, the heat convection disorder in the heating cylinder 3 can be suppressed, and the spinning of the yarn can also be reduced, so that a multifilament with a small yarn unevenness (U%) can be obtained. The multi-layer heating cylinder is more preferably composed of two or more layers, and the length of a single layer of the multi-layer heating cylinder is preferably in the range of 10-25mm.

When the polyamide multifilament of the embodiment of the present invention is manufactured, the cooling device 4 can adopt, for example: a cooling device that blows cooling and rectifying air from a certain direction, or an annular cooling device that blows cooling and rectifying air from the periphery toward the center, or a cooling device that blows cooling and rectifying air from the center. Any device such as an annular cooling device that blows cooling rectified air toward the periphery.

In order to achieve the desired flatness, it is necessary to increase the solidification point of the polymer (polyamide). This is due to the fact that the elastic force acting on the polymer (polyamide) acts in the direction that minimizes the surface area, and thus faces outward, so that the working time can be shortened. That is, for the polymer (polyamide) passing under the heating cylinder 3 and entering the cooling zone, it is necessary to make the solidification point as close as possible to the upper end of the cooling zone. As shown in Figure 1. The vertical distance LS (hereinafter referred to as "cooling start distance LS") from the bottom of the spinning nozzle 1 to the upper end of the cooling air blowing part of the cooling device 4 is from the viewpoint of obtaining the required flatness. It is preferable to set it within the range of 130 mm or less. Also, from the point of view of the Nusselt heat exchange type, the effective way to make the solidification point close to the upper end is to accelerate the cooling wind speed. The interval average of the lower end surface is preferably in the range of 30.0~40.0m/min. By setting the cooling wind speed to 30.0m/min On the other hand, the heat exchange speed of the polymer (polyamide) can be accelerated, so that the solidification point is close to the upper end surface of the cooling area, so that the required flatness can be easily achieved. On the other hand, from the viewpoint of operability, the cooling wind speed is preferably 40 m/min or less.

Like the cooling air speed, the cooling air temperature in the cooling area is also an important factor for heat exchange. The cooling air temperature is preferably below 20°C. By setting the cooling air temperature below 20°C, the heat exchange speed of the polymer (polyamide) can be accelerated, and the solidification point is close to the upper end of the cooling area, so the required flatness can be easily achieved.

When the polyamide multifilament according to the embodiment of the present invention is produced, the distance in the vertical direction from the position of the oil supply device 5, that is, from the bottom of the spinning nozzle 1 in FIG. 1 to the position of the oil supply nozzle of the oil supply device 5 Lg (hereinafter also referred to as "oil supply position Lg") varies according to the fineness of the monofilament and the cooling efficiency of the filament by the cooling device 4, and is preferably 800~1500mm. The oil supply position Lg is more preferably 1000~1300mm. When the oil supply position Lg reaches 800mm or more, the filament temperature drops to an appropriate level when the oil is applied; when it is less than 1500mm, the yarn swing caused by the downdraft is small, and a compound with low yarn unevenness (U%) can be obtained Silk. Also, when the oil supply position Lg is less than 1500mm, by shortening the distance between the solidification point and the oil supply position, the derivative flow is reduced and the spinning tension is reduced. This suppresses spinning orientation and improves elongation, and thus is preferable from the viewpoint of increasing strength such as improving hoop strength. When the oil supply position Lg reaches 800mm or more, the yarn from the spinneret to the oil supply guide is properly bent, and is not easily affected by the friction of the guide, which reduces the degree of reduction in high strength such as increased ring strength.

When producing the polyamide multifilament according to the embodiment of the present invention, it is preferable to install the fluid rotary nozzle device 6 before the take-off roll 7 . The fluid rotary nozzle (rotary nozzle) has the shape shown by the symbol 6a in Fig. 4(a) and Fig. 4(b), and imparts converging properties to the filaments by swirling flow W from one direction in the barrel. The length LA of the rotary nozzle is based on the fineness of the multifilament However, it is preferably 5 to 50 mm from the viewpoint of imparting converging properties.

Furthermore, the ejection pressure of the swirling flow W is preferably 0.05-0.20 MPa. By setting the discharge pressure within this range, appropriate bundling properties can be imparted to the filaments, reducing the decrease in elongation properties when stretching is performed under high tension, and making it difficult for monofilaments to loosen during stretching. Therefore, a polyamide multifilament with less fluff can be obtained even if the fineness is reduced.

In the production of the polyamide multifilament according to the embodiment of the present invention, the drawing is preferably multi-stage drawing of two or more stages. In the case of one-stage stretching, when high-magnification stretching is performed to obtain high-fiber modulus and high-strength raw filaments, the stretching tension becomes higher, or the traction point is located on the traction roller, resulting in deterioration of extensibility and decrease in strength, and Pilling occurs easily. By setting the multi-stage stretching at two or more stages, the load applied to the yarn during stretching can be distributed, and the pulling point can be stably placed between the rollers. Therefore, the elongation is stable, and the loop strength, 15% strength, and tensile strength are all high. Not only can fibers with high fiber modulus be easily obtained, but also fuzz-free polyamide multifilament can be easily obtained.

When producing the polyamide multifilament according to the embodiment of the present invention, from the viewpoint of achieving a loop strength of 12 cN/dtex or higher, the total draw ratio is preferably in the range of 3.5 to 5.0 times. The total elongation ratio is better at 3.8~4.7 times. The elongation ratio of the first stage is preferably 2.5 to 3.5 times, more preferably 2.7 to 3.3 times. Also, during stretching, it is preferable to heat the drawing roll 7 to 40-60°C, the first stretching roll 8 to 130-170°C, and the second stretching roll 9 to 150-200°C. The speed of the traction roller 7 is preferably 500-1300m/min, more preferably 700-1100m/min.

When producing the polyamide multifilament according to the embodiment of the present invention, the relaxation rate of the second stretching roll 9 and the relaxation roll 10 [(speed of the second stretching roll - speed of the relaxation roll)/(speed of the relaxation roll) x 100] is preferably set to 0~1.5%. When the relaxation rate is within this range, the relaxation rate is lower than that in the general production of polyamide multifilament, and heat setting can be performed with less relaxation. Therefore, the linearity of the molecular chain is improved, and the amorphous part inside the fiber becomes a uniform and moderately protruding structure, which can easily achieve high strength such as loop strength. If the relaxation rate is greater than 1.5%, the linearity of the molecular chain is reduced because the heat setting is carried out in a state of large relaxation, and it is difficult to achieve high strength such as improvement of loop strength.

By adopting the conditions of the direct spinning and stretching method as shown in Figure 1 above, it is possible to obtain polyamide multifilaments with a total fineness of 6~20 dtex, a high loop strength above 12 cN/dtex, and a high flatness of 1.5~5.0.

[Covered Elastic Yarn]

The polyamide multifilament system according to the embodiment of the present invention can be used as a covered yarn which is a covered yarn.

The covered elastic yarn (hereinafter also referred to as "covered yarn") according to the embodiment of the present invention is a covered elastic yarn in which the above-mentioned polyamide multifilament is arranged as a covered yarn. The covered yarn system includes, for example, a single covered yarn in which the elastic yarn is used as a core yarn and the covered yarn is wound in a single layer, and a double covered yarn in which the covered yarn is wound in two layers.

Elastic yarns can be used, for example: polyurethane-based elastic fibers, polyamide-based elastic fibers, polyester-based elastic fibers, natural rubber-based fibers, synthetic rubber-based fibers, butadiene-based fibers, etc. , as long as it is properly selected in accordance with elastic properties, heat setting properties, and durability. Among them, polyurethane-based elastic fibers and polyamide-based elastic fibers are preferable in terms of the above-mentioned properties.

The thickness of the elastic yarn varies according to the type of stockings and the setting of the tension pressure. In order to take into account durability, transparency, and softness, generally 8~40dtex is enough. Among them, the preferred elastic yarn thickness is 14~25dtex. By setting the thickness of the elastic yarn within this range, the stretchability, durability, softness, and transparency of stockings can be easily realized.

The covered twist system only needs to consider the fineness, shrinkage, product feel, transparency, durability, etc. of the covered yarn before designing. If the number of covering twists is increased, the apparent thickness will become thinner, and the feeling of transparency will tend to be improved. However, if it is too high, the elastic yarn will easily become too tight, and the durability will decrease, or the productivity of the covering step will decrease. . Also, if the number of covering twists is too low, the covering property will be lowered, and the durability, transparency, and softness will tend to be lowered. Therefore, for example, when using 6dtex covered yarn as a single covered yarn, the target number of covered twists should be set at 2000~2600T/m. Also, when it is a double-covered yarn, the target number of the upper twist may be 0.7 to 0.95 times the number of the lower twist. The twisting direction can be set in any state such as the same direction or the opposite direction for the bottom twist and the top twist. In order to suppress the torque, it is best to wrap in the opposite direction. In addition, the drafting ratio can also be designed according to the target tightness, for example, the drafting ratio is preferably set at 2.5~3.5 times.

In addition, when producing the covered elastic yarn according to the embodiment of the present invention, it is only necessary to perform covering processing according to a conventional method. For example, what is necessary is just to implement the processing described in Textile Encyclopedia (Japan, Maruzen Co., Ltd., published on March 25, 2014, p439). That is to say, if an example is given, the elastic yarn is pulled at a constant speed, and the covered yarn pre-wound on the H bobbin is wound on the elastic yarn according to a certain number of covering twists under the state of applying a certain draft between two rollers. yarn, and then the obtained covered elastic yarn is applied to the plain yarn winding.

The polyamide multifilament according to the embodiment of the present invention and the covered elastic yarn according to the embodiment of the present invention can be used in some stockings. Among them, it is preferable to use it on legs from the viewpoint of making use of the sheer feeling of stockings, the feeling of bare feet, and the glossy feeling with excellent shading effect. Here, the so-called stockings can be, for example: pantyhose, stockings, short stockings and other stockings, and the so-called leg, for example, in the case of pantyhose, means the range from the garter to the toes.

Furthermore, the knitting machine of silk stockings can use the usual sock knitting machine, there is no special limits. For example, a double-port or four-port yarn-feeding knitting machine can be used, and the covering yarn can be supplied and braided by a common method. In the case of single-covered yarns, it is preferable to use a method in which the single-covered yarns covered in the S direction and the single-covered yarns covered in the Z direction are interlaced. Other methods include, for example: cross knitting of single covering yarn and raw silk, cross knitting of double covering yarn and raw silk, flat knitting of double covering yarn and double covering yarn, etc. Also, the needle count of the knitting machine is about 360 to 474, and the lower the needle count, the higher the transparency and the poorer the durability tends to be. As the number of needles increases, the durability tends to decrease, but the sense of transparency tends to decrease. Therefore, the needle count can be selected according to the denier of the covered yarn and elastic yarn used, as well as the target durability, transparency, softness, etc. In one case, it is better to use the covered yarn 6~20dtex, and weave according to the needle count of 400~440.

Furthermore, the dyeing after knitting, the subsequent post-processing, and the final setting conditions can be done according to known methods. As dyes, acid dyes and reactive dyes can also be used. In addition, of course, the color and the like are not limited.

[Example]

Hereinafter, the present invention will be described in more detail using examples.

Hereinafter, evaluation methods for each evaluation item are described.

A. Tensile strength, elongation product, 15% strength

Fiber samples were measured according to "8.5 Tensile Strength and Elongation" of JIS L1013 (2010), and the tensile strength-elongation curve was drawn. As the test conditions, the type of the test machine is constant velocity extension, and it is carried out according to the grasping interval of 50cm and the tensile speed of 50cm/min. In addition, when the tensile strength at the time of cutting is less than the maximum strength, the maximum tensile strength and the elongation at that time are measured.

Elongation, tensile strength, strength-elongation product, and 15% strength are calculated according to the following formula.

Elongation = elongation when cut (%)

Tensile strength = tensile strength at cut (cN)/total denier (dtex)

Strength and elongation product={tensile strength (cN/dtex)}×{elongation (%)+100}/100

15% strength = tensile strength at 15% elongation (cN)/total denier (dtex)

B. Loop Strength

According to "8.7 Loop strength" of JIS L1013 (2010), the loop part is made in the center of the gripping space of the sample, and the measurement is carried out under the same conditions as the above-mentioned strength and elongation measurement. The loop strength is calculated according to the following formula.

Loop Strength = Tensile Strength at Cut (cN)/Total Denier (dtex)

C. Total fineness, single filament fineness

Install the fiber sample (multifilament) on a 1.125m/circle reel, make it rotate 500 times to make a ring-shaped skein, dry it with a hot air dryer (105±2°C×60 minutes), and use a scale to weigh the skein Yarn quality, the total titer is calculated from the value multiplied by the standard moisture regain. In addition, the standard moisture regain is set at 4.5%. The value obtained by dividing the calculated total fineness by the number of filaments was defined as the single filament fineness.

D. Relative viscosity of sulfuric acid (ηr)

0.25 g of a polyamide chip sample was dissolved so as to become 1 g with respect to 100 ml of sulfuric acid with a concentration of 98% by mass, and the flow time (T1) at 25° C. was measured using an Oswald viscometer. Next, the flow-down time (T2) of only sulfuric acid with a concentration of 98% by mass was measured. Let the ratio of T1 to T2 (that is, T1/T2) be the relative viscosity of sulfuric acid.

E. Silk unevenness (U%)

Using USTER (registered trademark) TESTER IV manufactured by Uster Technologies Co., Ltd., the fiber sample was measured according to sample length: 500m, measurement yarn speed V: 100m/min, Twister (number of revolutions): S twist, 30000/min, 1/2 Inert.

F. Flatness, cross-sectional shape

At any position of the fiber used in the covered yarn, cut a thin section toward the cross-sectional direction, use a transmission microscope to photograph all the filaments in the cross-section of the fiber, and use a printer (manufactured by Mitsubishi Electric Co., Ltd., SCT-P66) after printing out, use a scanner (GT-5500WINS manufactured by Seiko Epson Co., Ltd.) to capture (black and white photos, 400dpi), and use image processing software (Mitani Shoji Co., Ltd. system, WinROOF), calculate the ratio L/S of the diameter L of the circumscribed circle OL and the diameter S of the inscribed circle IC, and then calculate the flatness = b/a from the average value of the values obtained from all filaments. Also, from the photographs taken, it was visually confirmed whether or not the fiber had a flat fiber cross-section (small rectangular elliptical cross-sectional shape).

G. stockings evaluation

(a) Durability

According to the breaking strength test method according to the Mullen's breaking strength method (A method) described in JIS L1096 (2010), measure the breaking strength at any 3 places, take the average value, and perform 4-stage evaluation according to the following criteria. A and B were judged as durability passing.

A: 1.6kg/cm2 ^or more

B: More than 1.4kg/cm ² and less than 1.6kg/cm ²

C: More than 1.2kg/cm ² and less than 1.4kg/cm ²

D: Less than 1.2kg/cm ²

(b) Softness

For silk stockings, the softness was evaluated by inspectors (5 persons) experienced in hand feeling evaluation. Relative evaluation was performed using the 11dtex, 8-filament, nylon 6 multifilament of circular cross-section manufactured in the same manner as in Example 1 as a reference. The results are based on the evaluation scores of each examiner, from the average of 5 examiners (rounded off below the decimal point), 5 is set as A, 4 is set as B, 3 is set as C, and 1~2 is set as D. A and B were judged as qualified for softness.

5 points: very good

4 points: slightly excellent

3 points: normal

2 points: slightly worse

1 point: Poor

(c) Transparency

Evaluation samples were refined, undyed, and subjected to a subsequent finishing step, and evaluation was performed using white raw cloth. A and B are rated as qualified for transparency.

A: very good

B: Slightly excellent

C: Normal

D: slightly worse

(d) Aesthetics of web weaving

Evaluation samples were refined, undyed and subjected to subsequent finishing steps, Evaluation was performed using a white raw cloth. A and B are rated as qualified for the aesthetics of the weaving network.

A: very good

B: Slightly excellent

C: Normal

D: slightly worse

[Example 1]

(Manufacture of Polyamide Multifilament)

Polyamide-based Nylon 6 fragments with a sulfuric acid relative viscosity (ηr) of 3.3 and a melting point of 225°C were dried using a conventional method so that the moisture content was 0.03% by mass or less. The obtained nylon 6 chips were melted at a spinning temperature (melting temperature) of 298°C, and discharged from the spinning nozzle 1 (discharge amount: 18.9 g/min). Spinning spinneret 1 system uses number of holes 36,6 filaments/spinneret, as shown in Figure 5, is provided with the discharge hole of circular hole at slit two ends (discharge hole width is set as H, and discharge hole length is set as N. When the diameter of the round hole is set to D, N/H=4.9, D/H=1.4, and the spit hole width H is 0.07mm). The spinning machine used the spinning machine of the aspect shown in FIG. 1 to perform spinning. In addition, the heating cylinder 3 was used with a heating cylinder length L of 50 mm, and the ambient temperature in the heating cylinder 3 was set to 290° C. state. Each filament discharged from the spinning nozzle 1 is cooled and solidified to room temperature by the cooling device 4 having a cooling start distance LS: 102 mm, a cooling air temperature of 18° C., and a cooling air speed of 38 m/min. Then, set the oil supply position Lg from the spinneret face to 1300mm, apply the oil agent by the oil supply device 5, and at the same time make the filaments bundled to form multifilaments, and then use the fluid rotary nozzle device 6 with a rotary nozzle length LA of 25mm Give bundle. Convergence imparting is carried out in the fluid rotary nozzle device 6, as shown in FIG. 4, by spraying high-pressure air (rotary flow W) toward the traveling yarn (multifilament 20) from the direction of the arrow. The pressure of the injected air (revolving flow W) is set to 0.1MPa (flow rate 15L/ point). Then, the drawing ratio between the drawing roll 7 and the first stretching roll 8 becomes 2.9 times, and the first stage of stretching is performed, and then the stretching ratio between the first stretching roll 8 and the second stretching roll 9 becomes 1.5 times, Apply the extension of paragraph 2. Next, a relaxation heat treatment of 2.0% is performed between the second stretching roll 9 and the relaxation roll 10, and the yarn (multifilament) is entangled by the entanglement imparting device 11, and then coiled by the coiling device 12 at 3000 m/min. At this time, the total stretching ratio represented by the ratio of the drawing speed (the speed of the drawing roller 7) to the drawing speed (the speed of the second drawing roller 9) was adjusted to be 4.3 times. The surface temperature of each roll was set to 40°C for the take-off roll, 155°C for the first stretching roll, 185°C for the second stretching roll, and room temperature for the relaxation roll. The entanglement treatment is carried out in the entanglement imparting device 11 by spraying high-pressure air on the wandering yarn (multifilament) from a direction perpendicular to it. The pressure of the injected air was set at 0.2 MPa. In this way, nylon 6 multifilament with a total fineness of 9 dtex, 6 filaments, and a small cross-sectional shape is obtained. The results are shown in Table 1 for the shape evaluation of the obtained nylon 6 multifilament.

(Manufacturing of stockings)

The obtained multifilament was used as the covering yarn covering the elastic yarn, and the 18 denier polyurethane elastic yarn (manufactured by Nisshinbo Textile Co., Ltd., MOBILON (registered trademark) K-L22T) was used as the core yarn, and the draft was set to 3.5 times, covering according to the number of covering twist 2400t/m.

Using the above-mentioned covered elastic yarn, using the Super 4 knitting machine (400 needles) manufactured by Nagata Seiki Co., Ltd., the S-direction single-covered yarn and the Z-direction single-covered yarn are alternately supplied to the yarn feeder of the knitting machine. Only the covered yarn is used to create the leg braid. Next, use a soaping agent (NEWSUNREX (registered trademark) E; 2g/L (manufactured by Nikka Chemical Co., Ltd.)) to carry out refining at 60°C for 30 minutes, and then use an acid semi-milling dye (Telon Red A2R; 0.14%owf , Telon Yellow A2R; 0.16%owf, Telon Blue A2R; 0.12% owf (manufactured by DyStar, registered trademark of Telon)), leveling agent (SeraGaIN-FS; 0.5% owf (manufactured by DyStar)), pH slip agent (ammonium sulfate; 4.0% owf), bath ratio 1 : 50, 100 ℃ × 60 minutes, dyeing into light gray yellow (beige) color of the general color of pantyhose, and then use color fixing agent (HIFIX (registered trademark) SW-A; 5% owf (NAGASE-OG COLORS & CHEMICALS shares Co., Ltd.)), anti-residue agent (NWH201; 1% owf (SENKA Co., Ltd.)), sodium carbonate, perform color fixing treatment at 90°C×45 minutes, and perform final setting at 120°C for 30 seconds to form Tights products. Evaluation was performed on the legs of the obtained pantyhose products, and the results are shown in Table 1.

The obtained pantyhose was extremely excellent in all durability, softness, transparency, and netting aesthetics.

[Example 2]

Except for changing the number of holes and the output of the spinning nozzle, all the others were followed in the same manner as in Example 1 to obtain nylon 6 multifilaments with a total fineness of 6 dtex and 4 filaments, and weave them into stockings. The evaluation results are shown in Table 1.

[Example 3]

Except for changing the number of holes and the discharge rate of the spinning nozzle, all the others were in accordance with the same method as in Example 1 to obtain nylon 6 multifilaments with a total fineness of 20 dtex and 14 filaments, and weave them into stockings. The evaluation results are shown in Table 1.

[Example 4]

Executed in such a way that the stretching ratio between the pulling roll 7 and the first stretching roll 8 becomes 2.9 times The stretching in the first stage is followed by the stretching in the second stage so that the stretching ratio between the first stretching roll 8 and the second stretching roll 9 becomes 1.2 times. Also, the total stretching ratio represented by the ratio of the drawing speed (the speed of the drawing roller 7) to the drawing speed (the speed of the second drawing roller 9) was adjusted to 3.5 times. Except for the above, all the others are all according to the same method as in Example 1 to obtain nylon 6 multifilaments with a total fineness of 9 dtex and 6 filaments, and weave them into stockings. The evaluation results are shown in Table 1.

[Example 5]

The first stage of stretching is performed so that the stretching ratio between the drawing roll 7 and the first stretching roll 8 becomes 3.4 times, and then the second stage is executed so that the stretching ratio between the first stretching roll 8 and the second stretching roll 9 becomes 1.4 times extension. Also, the total stretching magnification represented by the ratio of the drawing speed (the speed of the drawing roller 7) to the drawing speed (the speed of the second drawing roller 9) was adjusted to 5.0 times. Except for the above, all the others were all followed the same method as in Example 1 to obtain nylon 6 multifilament with a total fineness of 9 dtex and 6 filaments, and weave it into stockings. The evaluation results are shown in Table 1.

[Example 6]

Except that in the discharge hole of the spinning spinneret, the width of the discharge hole is set as H, the length of the discharge hole is set as N, and the change is N/H=3.9, the rest are all according to the same method as in Example 1 to obtain a total fineness of 9dtex , 6 filaments of nylon 6 multifilament, and woven into stockings. The evaluation results are shown in Table 1.

[Example 7]

Except for the discharge hole of the spinning nozzle, let the discharge hole width be H, and the discharge hole length be The degree is set as N, except that it is changed to N/H=8.8, and all the others are all according to the same method as in Example 1 to obtain nylon 6 multifilaments with a total fineness of 9dtex and 6 filaments, and weave them into stockings. The evaluation results are shown in Table 1.

[Example 8]

Except that the outlet hole width H of the spinning nozzle was changed to 0.08 mm, all the others were followed in the same manner as in Example 1 to obtain a nylon 6 multifilament with a total fineness of 9 dtex and 6 filaments, and weave it into stockings. The evaluation results are shown in Table 1.

[Example 9]

Except that the width H of the discharge hole of the spinning nozzle was changed to 0.06mm, the rest were all followed in the same manner as in Example 1 to obtain a nylon 6 multifilament with a total fineness of 9 dtex and 6 filaments, and weave it into stockings. The evaluation results are shown in Table 1.

[Example 10]

Except that the cooling wind speed was changed to 30m/min, all the others were in accordance with the same method as in Example 1 to obtain nylon 6 multifilaments with a total fineness of 9dtex and 6 filaments, and weave them into stockings. The evaluation results are shown in Table 1.

[Example 11]

Except that the length L of the heating cylinder was changed to 75 mm, the rest were all followed the same method as in Example 1 to obtain nylon 6 multifilament with a total fineness of 9 dtex and 6 filaments, and weave it into stockings. The evaluation results are shown in Table 1.

[Table 1]

[Comparative example 1]

As shown in FIG. 2 , the second drawing roll 9 and the relaxation roll 10 were not provided, and the drawing ratio between the drawing roll 7 and the first drawing roll 8 was set to 2.7 times. As the spinning nozzle 1, one with a discharge hole width H of 0.10 mm was used, and each filament discharged from the spinning nozzle 1 was passed through a cooling device 4 with a wind speed of 25 m/min. Except for the above, all the others are all according to the same method as in Example 1 to obtain nylon 6 multifilaments with a total fineness of 9 dtex and 6 filaments, and weave them into stockings. The evaluation results are shown in Table 2.

As in Patent Document 2, the conditions for improving the tenacity product are only applied to the conditions of Patent Document 1, and the produced multifilament of Comparative Example 1 shows a decrease in flatness. Also, the loop strength was low as a result. Therefore, the softness, transparency, aesthetics and durability of silk stockings are poor.

[Comparative example 2]

Except for changing the number of holes and the discharge rate of the spinning nozzle, all the others were in accordance with the same method as in Example 1 to obtain nylon 6 multifilaments with a total fineness of 5 dtex and 3 filaments, and weave them into stockings. The evaluation results are shown in Table 2.

Since the multifilament obtained in Comparative Example 2 has a finer fineness, not only the yarn strength is reduced, but also the loop strength is also reduced. Therefore, the obtained stockings were poor in durability.

[Comparative example 3]

Except for changing the number of holes and the discharge rate of the spinning nozzle, all the others were in accordance with the same method as in Example 1 to obtain nylon 6 multifilaments with a total fineness of 22 dtex and 17 filaments, and weave them into stockings. The evaluation results are shown in Table 2.

The multifilament obtained in Comparative Example 3 has relatively thick fineness, so the softness and transparency of the obtained silk stockings are relatively poor.

[Comparative example 4]

The first stage of stretching is carried out so that the stretching ratio between the drawing roll 7 and the first stretching roll 8 becomes 2.7 times, and then the second step is carried out so that the stretching ratio between the first stretching roll 8 and the second stretching roll 9 becomes 1.2 times. segment extension. Also, the total stretching ratio represented by the ratio of the drawing speed (the speed of the drawing roller 7) to the drawing speed (the speed of the second drawing roller 9) was adjusted to 3.2 times. Except for the above, all the others are all according to the same method as in Example 1 to obtain nylon 6 multifilaments with a total fineness of 9 dtex and 6 filaments, and weave them into stockings. The evaluation results are shown in Table 2.

The multifilament obtained in Comparative Example 4 had a low total elongation ratio, so the loop strength was low, and the durability of the obtained stockings was poor.

[Comparative Example 5]

Except that in the discharge hole of the spinning spinneret, the width of the discharge hole is set as H and the length of the discharge hole is set as N, which is changed to N/H=3.5, the rest are obtained in the same way as in Example 1 to obtain the total fineness 9dtex, 6-filament nylon 6 multifilament, and woven into stockings. The evaluation results are shown in Table 2.

Because the multifilament obtained in Comparative Example 5 has low flatness, the softness, transparency and netting aesthetics of the obtained silk stockings are all poor.

[Comparative Example 6]

Except for the discharge hole of the spinning nozzle, let the discharge hole width be H, and the discharge hole length be When the density is set to N, except that it is changed to N/H=10.7, the rest are all according to the same method as in Example 1 to obtain nylon 6 multifilaments with a total fineness of 9 dtex and 6 filaments, and weave them into stockings. The evaluation results are shown in Table 2.

Since the multifilament obtained in Comparative Example 6 had a high flatness, the loop strength was low, and the durability of the obtained stockings was poor.

[Comparative Example 7]

Except that the outlet hole width H of the spinning nozzle was changed to 0.09 mm, all the others were followed in the same manner as in Example 1 to obtain nylon 6 multifilaments with a total fineness of 9 dtex and 6 filaments, and weave them into stockings. The evaluation results are shown in Table 2.

In the multifilament obtained in Comparative Example 7, since the width H of the discharge hole was large, the discharge linear speed decreased and the loop strength decreased. Therefore, the obtained stockings were poor in durability.

[Comparative Example 8]

Except that the length L of the heating cylinder was changed to 25 mm, the rest were all followed the same method as in Example 1 to obtain nylon 6 multifilament with a total fineness of 9 dtex and 6 filaments, and weave it into stockings. The evaluation results are shown in Table 2.

The multifilament obtained in Comparative Example 8 was short in length L of the heating cylinder, so the ambient temperature was 250°C, and the alignment of the polyamide polymer in the gradually cooling region from the spinneret surface to the bottom of the heating cylinder was insufficiently relaxed, so it was flat. The degree is also increased, and the ring strength is reduced. Therefore, the obtained stockings were poor in durability.

[Comparative Example 9]

Except for changing the length L of the heating cylinder to 100mm, the rest are implemented in accordance with The same method of example 1, obtains the nylon 6 multifilament of total denier 9dtex, 6 filaments, and is woven into silk stockings. The evaluation results are shown in Table 2.

In the multifilament obtained in Comparative Example 9, since the length L of the heating cylinder was longer, the cooling start distance LS was longer, resulting in a decrease in flatness. Therefore, the softness, transparency, and netting aesthetics of the obtained stockings deteriorate.

[Comparative Example 10]

Except that the cooling wind speed was changed to 25m/min, all the others were in accordance with the same method as in Example 1 to obtain nylon 6 multifilaments with a total fineness of 9dtex and 6 filaments, and weave them into stockings. The evaluation results are shown in Table 2.

The multifilament obtained in Comparative Example 10 has a slow cooling wind speed, so the solidification point does not become the upper end surface of the cooling region, and the flatness decreases. Therefore, the softness, transparency and netting aesthetics of the obtained silk stockings are all poor.

[Table 2]

The present invention has been described in detail with reference to specific embodiments, but various changes and modifications can be made without departing from the spirit and scope of the present invention, which can be easily conceived by those skilled in the art. This application is based on the Japanese patent application (Japanese Patent Application No. 2018-218431) filed on November 21, 2018, and its content is referred to in this case.

a: short diameter

b: long diameter

Claims (3)

A polyamide multifilament with a total fineness of 6~20dtex, a loop strength of more than 12cN/dtex, and a flatness represented by the ratio (b/a) of the long diameter b to the short diameter a of the single fiber cross section of 1.5 ~5.0. The polyamide multifilament according to claim 1, wherein the tensile strength at 15% elongation is 5.0 cN/dtex or more. A covered elastic yarn, the polyamide multifilament of claim 1 or 2 is configured as a covered yarn.

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