JPWO2018021011A1 - Polyamide multifilament and lace knit using it, stocking - Google Patents

Abstract

A polyamide multifilament characterized in that the tensile strength at 15% elongation is 4.0 to 6.0 cN / dtex, the strength and elongation product is 10.0 or more, and the yarn spots (U%) are 1.2 or less. The present invention provides a high-strength polyamide multifilament which can obtain a lace knit having excellent softness, durability and transparency and excellent in durability and having a beautiful pattern.

Description

  The present invention relates to polyamide multifilaments. More specifically, when the polyamide multifilament of the present invention is used for a stocking, the stocking having excellent softness, durability and transparency is provided, and when used for a ground thread of a lace base, the durability is excellent and the handle is The present invention relates to a polyamide multifilament that can provide a lace fabric that looks beautiful.

  Polyamide fibers and polyester fibers which are synthetic fibers are widely used in clothing and industrial applications because they have excellent mechanical and chemical properties. In particular, polyamide fiber is widely used in general clothing applications such as stocking, innerwear, sportswear, etc., because it has excellent properties in its unique softness, high strength, coloring during dyeing, heat resistance, hygroscopicity, etc. ing.

  As consumer needs of the race, in order to make the pattern look beautiful, the durability is as usual, and the feeling of transparency of the lace base yarn has been desired. As consumers' needs for stockings, in order to give comfortable feeling and bare skin feeling, durability was conventionally comparable, and the pursuit of softness and transparency was desired. That is, when replaced with a polyamide fiber for clothing, the strength is strongly desired to be as fine as ever.

  In order to solve these problems, various techniques have been proposed for strengthening polyamide fibers. For example, Patent Document 1 proposes a lace knit made of high viscosity type nylon 6 filaments having an elongation of 51 to 64% and a strength of 4.2 to 6.5 cN / dtex.

  Patent Document 2 proposes a stocking made of a polyamide filament having an elongation of 40 to 50%, a tensile elongation product of 9.1 or more and about 9.8.

  Patent Document 3 proposes a tire cord or belt made of a polyamide-based fiber having an elongation of about 16 to 18%, a strength of 9.8 cN / dtex or more, and a tensile elongation product of about 11.4 to 12.2 cN / dtex. It is done.

JP, 2003-129331, A International Publication No. 2016/76184 Japanese Patent Application Laid-Open No. 63-159521

  However, according to the method described in Patent Document 1, although a lace with a beautiful handle can be obtained, the fiber modulus and the tensile elongation product are low, and the product strength of the lace knitted fabric is not satisfactory.

  When the method described in Patent Document 2 is used by developing it to a fineness suitable for coating yarn of single covering elastic yarn, the fiber modulus and the tensile elongation product are low, and the product strength of the stocking is not satisfactory.

  When the method described in Patent Document 3 was developed for use in clothing, the fiber modulus was too high, and it was inferior in high-order passability such as yarn breakage and fuzz generation in the production process of laces and stockings.

  The present invention solves the above-mentioned problems, and it is an object of the present invention to provide a high strength polyamide multifilament having a high tensile elongation product and a suitable fiber modulus. More specifically, the polyamide multifilament having a high strength elongation product and an appropriate fiber modulus provides excellent high-order passage and product quality, enables finening, and maintains the durability while maintaining the transparency of the lace base yarn. It is an object of the present invention to provide a lace knitted fabric in which the pattern looks beautiful and a stocking having excellent transparency and softness.

  In order to solve the above-mentioned subject, the present invention adopts the following composition.

  (1) Polyamide mulch characterized in that the tensile strength at 15% elongation is 4.0 to 6.0 cN / dtex, the tenacity and elongation product is 10.0 or more, and the yarn spots (U%) are 1.2 or less. filament.

  (2) The polyamide multifilament according to the above (1), which has a single yarn fineness of 1.3 to 3.4 dtex.

  (3) The polyamide multifilament according to the above (1) or (2), which has an elongation of 30 to 50%.

  (4) The polyamide multifilament according to any one of the above (1) to (3), wherein the sum of the crystalline amount and the rigid non-crystalline amount is 70 to 90%.

  (5) A lace knit using the polyamide multifilament according to any one of the above (1) to (4) as a lace base yarn.

  (6) A stocking in which the polyamide multifilament according to any one of the above (1) to (4) is used as a covering coated yarn and the covering yarn is used in part.

  The polyamide multifilament of the present invention is a high strength polyamide multifilament having a high strength elongation product and a proper fiber modulus. Furthermore, the polyamide multifilament of the present invention is excellent in high-order passage and product quality, can be reduced in fineness, maintain durability, increase the transparency of the lace base yarn, and make the pattern look beautiful It is possible to obtain a lace knit, a stocking having excellent transparency and softness.

BRIEF DESCRIPTION OF THE DRAWINGS One embodiment of the manufacturing apparatus which can be preferably used for the manufacturing method of the polyamide multifilament of this invention is shown. It is a schematic cross-sectional model figure which shows the spinneret and heating cylinder which can be preferably used for the manufacturing method of the polyamide multifilament of this invention.

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

  The polyamide multifilament of the present invention has a tensile strength of 4.0 to 6.0 cN / dtex at 15% elongation, a tenacity and elongation product of 10.0 or more, and a yarn spot (U%) of 1.2 or less. It features.

  The polyamide constituting the polyamide multifilament of the present invention is a resin composed of a polymer having a so-called hydrocarbon group linked to the main chain via an amide bond, and such a polyamide is excellent in threadability and mechanical properties. In particular, polycaproamide (nylon 6) and polyhexamethylene adipamide (nylon 66) are preferred, and polycaproamide (nylon 6) is more preferred because of its difficulty in gelation and good spinning properties. In the above, mainly, in polycaproamide, ε-caprolactam constituting polycaproamide is a constituent unit, and in polyhexamethylene adipamide, hexamethylene diammonium adipate constituting polyhexamethylene adipamide is a constituent unit As 80 mol% or more, more preferably 90 mol% or more. Other components are not particularly limited. For example, polydodecanoamide, polyhexamethylene adipamide, polyhexamethylene azelamide, polyhexamethylene sebacamide, polyhexamethylene dodecanoamide, polymethaxylylene adipa And monomers such as amino carboxylic acid, dicarboxylic acid and diamine which are monomers constituting the polymer, polyhexamethylene terephthalamide, polyhexamethylene isophthalamide and the like.

  Further, in order to effectively exhibit the effects of the present invention, it is preferable that the polyamide does not contain various additives such as a matting agent represented by titanium oxide, but the additives such as a heat-resistant agent are not added May be contained as required. Moreover, the content may be mixed as needed between 0.001-0.1 wt%.

  The polyamide multifilament of the present invention is required to have all of 15% strength, tensile elongation product and U% in the above ranges. That is, by reducing the fineness, the transparency of the lace base yarn is increased and the lace knitted fabric with a beautiful pattern and the stocking having excellent transparency and softness can be obtained, but the product strength is lowered and the durability is actually improved. It becomes the level which can not stand use. In order for the durability to be at a level that can withstand actual use, it is necessary to increase the strength and elongation product. In addition, in order to maintain high-order passability and product quality, it is necessary to make the strength 15% and U% appropriate.

  Therefore, the inventors of the present invention diligently study and are superior in high-order passing property and product quality, excellent in durability, and a lace knitted fabric with excellent transparency and softness, in which the transparency of the lace base yarn is increased and the pattern looks beautiful. It has been found that 15% strength, strength and elongation product, and U% are essential areas in order to provide a stocking having.

  The polyamide multifilament of the present invention is required to have a strength and elongation product of 10.0 or more. By setting it as this range, the durability of a stocking or a race becomes the level which endures actual use. If the strength-elongation product is less than 10.0, the durability of the stocking or the lace will be at a level which can not withstand actual use, and yarn breakage in the high-order processing step will increase and the high-order passability will deteriorate. It is further preferable that the polyamide multifilament of the present invention has a tenacity and elongation product of 10.3 or more. Also, although the strength and elongation product is preferably as large as possible, the upper limit value in the present invention is about 11.0.

  The polyamide multifilament of the present invention has a tensile strength at 15% elongation (hereinafter referred to as "15% strength") of 4.0 to 6.0 cN / dtex, which is one index of raw yarn physical properties. It is necessary to be there. The measurement of 15% strength is measured according to JIS L1013-2010-tensile strength and elongation, and a tensile strength-elongation curve is drawn, and the value obtained by dividing the tensile strength (cN) at 15% elongation by the fineness Of 15% strength. The 15% strength is a value simply representing the fiber modulus, and the higher the 15% strength, the higher the gradient of the tensile strength-elongation curve and the higher the fiber modulus, while the lower the 15% strength, the tensile strength. -It shows that the slope of the elongation curve is low and the fiber modulus is low.

  By setting the polyamide multifilament of the present invention in such a range, the durability of the stocking or lace knitted fabric becomes a level that withstands actual use, and the softness is also excellent. When the 15% strength is less than 4.0 cN / dtex, the strength and elongation product decreases, and the durability of the stocking and the lace knitted fabric becomes a level which can not withstand actual use. If the 15% strength exceeds 6.0 cN / dtex, the elongation decreases, the texture of the stocking or lace knit becomes hard and the softness decreases, and the yarn breakage in the high-order processing step increases and the high-order passage And the product quality is reduced. Preferably it is 4.5-5.5 cN / dtex.

  The polyamide multifilament of the present invention preferably has an elongation of 30 to 50%. By setting it as this range, the thread breakage in a high-order processing process reduces, and high-order passage property and product quality become favorable. In particular, when knitting and weaving at high speed, it is excellent in high-order passage. When the elongation is 30% or more, there are few yarn breakages in high-order processing steps such as a stocking production step (covering yarn production step and a stocking knitting step) and a lace knitting production step (warping step and weaving step) Next passability is good. Furthermore, the texture of the stocking and lace knit is soft and good. If the elongation is 50% or less, the strength-elongation product is sufficient, the durability of the stocking and the lace knitted fabric can withstand the actual use, and the yarn breakage in the high-order processing process is small and the high-order passageability Product quality also improves. More preferably, it is 35 to 45%.

  The polyamide multifilament of the present invention preferably has a sum of the crystal amount and the rigid non-crystal amount of 70 to 90%. The crystal amount and the rigid amorphous amount are values calculated as follows.

  The amount of crystallization (Xc) is calculated according to equation (1) by calculating the difference (ΔHm−ΔHc) between the heat of fusion and the amount of cold crystallization heat by the DSC method. Here, ΔHm 0 is the heat of fusion of the crystalline polyamide, and its value is 229.76 J / g.

  The rigid amorphous amount (Xra) is calculated from the crystalline amount (Xc) and the movable amorphous amount (Xma) according to the equation (2). The movable amorphous amount (Xma) is calculated from the specific heat change (ΔCp) before and after the glass transition on the temperature-heat flow rate reversible curve by temperature modulation DSC method (TMDSC). Here, ΔCp uses the specific heat gap before and after the glass transition calculated by extrapolating the tangent to the temperature-heat flow reversible curve before and after the glass transition. The movable amorphous amount (Xma) is calculated by equation (3). Here, ΔCp0 is a specific heat difference around the Tg of the amorphous polyamide, and the value is 0.4745 J / g.

  The amount of rigid amorphous was calculated from the average value of two measurements of temperature modulation DSC and DSC.

Crystal amount: Xc (%) = (ΔHm-ΔHc) / ΔHm 0 × 100 (1)
Rigid amorphous amount: Xra (%) = 100-(Xc + Xma) (2)
Mobile amorphous amount: Xma (%) = ΔCp / ΔCp0 × 100 (3).

  The sum of the amount of crystallization and the amount of rigid non-crystalline amount mentioned here is a value simply representing the degree of relaxation of the orientation of the molecular chain of the polyamide polymer. When the sum of the crystal amount and the rigid non-crystalline amount is high, the strain of the molecular chain is small and the fiber is highly crystalline. When the sum of the crystalline amount and the rigid non-crystalline amount is low, the molecular chain entanglement is large, the crystal Indicates that it is a low-quality fiber. By setting the sum of the crystalline amount and the rigid non-crystalline amount to 90% or less, the amount of distortion of molecular chains of the polyamide polymer becomes appropriate, and polyamide fibers not having high crystallinity can be obtained, and the texture and softness of the stocking and lace knitted fabric Excellent in quality. By setting the sum of the crystalline amount and the rigid non-crystalline amount to 70% or more, the molecular chain of the polyamide polymer can be strained appropriately, so that a polyamide fiber having excellent crystallinity can be obtained, and the durability of the stocking or lace knitted fabric is excellent. . More preferably, it is 75 to 85%.

  The polyamide multifilament of the present invention needs to have a U% of 1.2 or less. With this range, the product quality is excellent. If the U% exceeds 1.2, after dyeing a knitted lace, the thick portion of the yarn becomes deep-stained and streaks occur, resulting in poor appearance and inferior product quality. More preferably, it is 1.0 or less for stocking applications and 1.0 or less for lace knit applications. In addition, the smaller U% is more preferable, but the lower limit value in the present invention is about 0.4.

  The total fineness of the polyamide multifilament of the present invention is preferably 4.0 to 33.0 dtex in terms of clothing use. More preferably, 4.0 to 11.0 dtex for stocking application and 20.0 to 30.0 dtex for racing application.

  The polyamide multifilament of the present invention preferably has a single yarn fineness of 1.3 to 3.4 dtex. By setting it as this range, it is excellent in durability and softness of a stocking or a race. More preferably, it is 1.6 to 3.2 dtex.

  The polyamide multifilament of the present invention preferably has a sulfuric acid relative viscosity of 2.5 to 4.0. More preferably, it is 3.2-3.8. By setting the relative viscosity of sulfuric acid to 2.5 to 4.0, the durability of the stocking or lace knitted fabric becomes a level that can withstand actual use. Furthermore, the product quality is good.

  The cross-sectional shape of the polyamide multifilament of the present invention is not particularly limited. For example, a round cross section, a flat cross section, a lens type cross section, a trilobal cross section, a multi-lobal cross section, and the same number of recesses as 3 to 8 convex sections It may be a modified cross section having a hollow section, a hollow cross section or any other known known cross section.

  Next, an example of the method for producing the high-strength polyamide multifilament of the present invention will be specifically described. FIG. 1 shows an embodiment of a direct spin-drawing apparatus for producing a high-strength polyamide multifilament according to the present invention.

  The polyamide multifilament of the present invention melts the polyamide resin, measures and transports the polyamide polymer with a gear pump, and is finally extruded from the discharge holes provided in the spinneret 1 to form each filament. The filaments discharged from the spinneret 1 in this manner are surrounded by the gas supply device 2 for blowing out steam to suppress the time-dependent contamination of the spinneret shown in FIG. 1 and the entire circumference provided for gradual cooling. The yarn is passed through a multilayer heating cylinder 3 and a cooling device 4 to cool and solidify the yarn to room temperature. After that, oiling is applied by the feeding device 5 and each filament is converged to form a multifilament, and it is entangled by the fluid entangled nozzle device 6 and passes through the take-off roller 7 and the drawing roller 8. Stretch according to the ratio of the circumferential speed of Furthermore, the yarn is heat-treated by heating the drawing roller 8 and taken up by the winding device 9.

  In the production of the polyamide multifilament of the present invention, the relative viscosity of sulfuric acid of the polyamide resin is preferably 2.5 to 4.0. By setting this range, a high strength polyamide multifilament having a high strength and elongation product can be obtained.

  The melting temperature is preferably higher than 20 ° C. and lower than 95 ° C. with respect to the melting point of the polyamide.

  In the production of the polyamide multifilament of the present invention, the heating cylinder 3 needs to be provided on the upper part of the cooling device 4 so as to surround each filament in the entire circumference. By setting the heating cylinder above the cooling device 4 and setting the ambient temperature in the heating cylinder within the range of 100 to 300 ° C., the polyamide polymer discharged from the spinneret 1 is less likely to be thermally degraded, and oriented It can be relieved. The orientation relaxation by slow cooling from the die surface to cooling provides a multifilament having a high strength and elongation product of 15% strength. When the heating cylinder is not installed, there is a tendency that it is difficult to obtain fibers satisfying both the 15% strength and the strength and elongation product because the relaxation of orientation due to slow cooling from the die surface to cooling is insufficient.

  In the production of the high strength polyamide multifilament of the present invention, the heating cylinder needs to be multilayer. Patent Document 3 proposes a heating cylinder for maintaining the atmosphere temperature immediately below the die at 250 to 450 ° C. for slow cooling, but the polyamide multifilament of the present invention is effective in the area of fineness for industrial use. In the fineness region for clothing like this, since the temperature distribution in the heating cylinder is constant, the thermal convection is likely to be disturbed, which affects the solidified state of each filament and causes the deterioration of U% It becomes. Therefore, by setting the heating cylinder in multiple layers and gradually reducing the temperature setting from the upper layer to the lower layer, thermal convection from the upper layer to the lower layer is intentionally created, and the downward flow of air in the same direction as the accompanying flow of yarn. This suppresses the disturbance of the thermal convection in the heating cylinder, reduces the yarn sway, and obtains a small multifilament of U%.

  The multilayer heating cylinder length L is preferably 40 to 100 mm although it depends on the fineness of the filament. Moreover, it is preferable that a multilayer heating pipe | tube is comprised from two or more layers, and the single layer length L1 of a multilayer heating pipe | tube has the preferable range of 10-25 mm.

  Further, the ambient temperature in the multilayer heating cylinder is in the range of 100 to 300 ° C., and it is necessary to provide a gentle temperature gradient between each layer. For example, when the multilayer heating cylinder length L is 75 mm and the single layer length L1 is 25 mm, the upper atmosphere temperature is 250-300 ° C., the middle atmosphere temperature is 200-250 ° C., the lower atmosphere temperature 100-200 ° C. It is necessary to

  With this configuration, the atmospheric temperature profile between the die and the cooling can be controlled stepwise at 100 to 300 ° C., and a high strength polyamide multifilament of 15% strength, tensile elongation product, and U% can be obtained.

  In the production of the polyamide multifilament of the present invention, the cooling device 4 is a cooling device that blows out the cooled rectified air A from a certain direction, or an annular cooling device that blows out the cooled rectified air A from the outer peripheral side toward the central side, or It can be manufactured by any method, such as an annular cooling device that blows out the cooling rectified air toward the outer periphery. The vertical distance LS (hereinafter referred to as the cooling start distance) from the lower surface of the spinneret to the upper end of the cooling air blowout portion of the cooling device 4 is in the range of 159 to 219 mm to suppress yarn swaying and U% The point is preferable, and 169 to 189 mm is more preferable. With regard to the cooling air velocity blown out from the cooling air outlet surface, the average of the sections from the upper end face to the lower end face of the cooling outlet portion is in the range of 20.0 to 40.0 (m / min) U% and strong It is preferable from the point of elongation product.

  In the production of the polyamide multifilament of the present invention, the position of the fueling device 5, that is, the vertical distance Lg from the lower surface of the spinneret in FIG. 1 to the fueling nozzle position of the fueling device 5 (hereinafter referred to as the fueling position) And although it depends on the cooling efficiency of the filament from the cooling device, 800 to 1500 (mm) is preferable, and more preferably 1000 to 1300 (mm). When it is 800 (mm) or more, the filament temperature is lowered to an appropriate level at the time of oil application, and when it is 1500 (mm) or less, the yarn swaying by the downdraft is small, and a low multifilament of U% is obtained. In the case of 1500 (mm) or less, the distance from the solidification point to the refueling position is shortened, the accompanying flow is reduced, and the spinning tension is reduced, so that the spinning orientation is suppressed and the drawability is excellent. High strength multifilament having high strength and elongation product and 15% strength can be obtained. When it is 800 (mm) or more, the yarn bending from the mouthpiece to the oil supply guide becomes appropriate, and the influence by the rubbing with the guide is hardly affected, and the reduction in strength and elongation product and 15% strength decreases.

  In the production of the polyamide multifilament of the present invention, the spinning speed is preferably 1000 to 2000 m / min, which is a low speed area of the take-up roller 7, and it becomes possible to suppress draft stretching unevenness and equalize yarn cooling. , U% can be as low as 1.2 or less. In addition, in the case of 2000 m / min or less, while the spinning orientation is suppressed, the slow cooling effect of the heating cylinder is promoted, so that the strain relaxation of the molecular chain becomes large, and the strength elongation of 15% High high strength multifilament is obtained.

  Further, heat treatment is performed using the drawing roller 8 as a heating roller, and the heat setting length is preferably 500 to 1,200 mm, and the heat treatment temperature is preferably 120 to 180 ° C. It is because it becomes possible to design the heat contraction of a multifilament by giving appropriate heat treatment. By setting the heat set length to 500 mm or more, the crystallization of the fibers becomes sufficient, so the strength becomes 15% high, and the product is excellent in durability. When the heat setting length is 1200 mm or less, the crystallization of the fiber does not proceed too much, and the 15% strength is in an appropriate range and the texture of the product is soft. Both are high strength polyamide excellent in process passability in higher order processing steps. Multifilament is obtained.

  In the polyamide multifilament of the present invention, the heating cylinder is disposed at the upper part of the cooling device 4, the ambient temperature in the heating cylinder is in the range of 100 to 300 ° C., and the heating cylinder is a multilayer type. A temperature gradient is provided inside to intentionally create a downdraft in the same direction as the accompanying flow of yarn, the oiling position 800 to 1500 mm from the base surface, the spinning speed 1000 to 2000 m / min, and the heat set length after drawing 500 It can manufacture by setting it as -1200 mm.

  By adopting the conditions in such a direct spinning and drawing method, a high tenacity product of 10.0 cN / dtex or more, 15% strength of 4.0 to 6.0 cN / dtex, U% of 1.2 or less High strength polyamide multifilament is obtained.

  The polyamide multifilament of the present invention is supplied to a lace knitting machine as raw silk as raw silk and knitted on a lace ground in the usual manner. The race site may be a normal knitting structure such as emboloidal race, russell race, river race and the like.

  The polyamide multifilament of the present invention is used as a covering yarn of covering yarn. The covering yarn is used as a single covering yarn in which an elastic yarn such as a polyurethane elastic fiber or a polyamide elastomer elastic fiber is used as a core yarn and the covering yarn is wound in a single layer, and a double covering yarn in which the covering yarn is double wound.

  The polyamide multifilament of the present invention is used in a stocking which partially uses the covering yarn described above. In addition, as a stocking knitting machine, an ordinary sock knitting machine can be used without limitation, and a usual method of supplying and covering the covering yarn of the present invention using a 2- or 4-part feeding machine. It should be organized with

  Furthermore, dyeing after knitting and subsequent post-processing and final setting conditions may be performed according to a known method, and the use of acid dyes and reactive dyes as dyes, color and the like are not limited.

  Hereinafter, the present invention will be described in more detail by way of examples.

A. Strength, elongation, strength elongation product, 15% strength JIS L1013-2010-A fiber sample is measured according to tensile strength and elongation, and a tensile strength-elongation curve is drawn. As a test condition, the type of tester was a constant speed extension type, a grip interval of 50 cm, and a tensile speed of 50 cm / min. In addition, when the tensile strength at the time of cutting was smaller than the maximum strength, the maximum tensile strength and the elongation at that time were measured.

  The strength and strength and elongation product were determined by the following equation.

Elongation = elongation at break (%)
Strength = tensile strength at cutting (cN) / fineness (dtex)
Strength and elongation product = {strength (cN / dtex)} × {elongation (%) + 100} / 100
15% strength = tensile strength at 15% elongation (cN) / fineness (dtex).

B. The fiber sample is set on a measuring instrument with a total fineness and a single yarn fineness of 1.125 m / perimeter, and it is rotated 500 times to make a loop-like skein and dried with a hot air dryer (105 ± 2 ° C. × 60 minutes) The weight of the skein was measured with a balance, and the fineness was calculated from the value obtained by multiplying the official moisture percentage. The official moisture content was 4.5%.

C. Sulfuric acid relative viscosity (η r)
A polyamide chip sample or a fiber sample of 0.25 g was dissolved to 1 g per 100 ml of sulfuric acid having a concentration of 98 mass%, and the flow time (T1) at 25 ° C. was measured using an Ostwald viscometer. Subsequently, the flow time (T2) of only sulfuric acid having a concentration of 98% by mass was measured. The ratio of T1 to T2, that is, T1 / T2 was taken as the relative viscosity of sulfuric acid.

D. Thread spot (U%)
A fiber sample was measured at a sample length of 500 m, a measurement yarn velocity V of 100 m / min, a Twister of S, 30000 / min, and 1/2 Inert using USTER TESTER IV manufactured by zellweger uster.

E. The difference between the heat of fusion and the heat of cold crystallization (ΔHm−ΔHc) is calculated by the DSC method, and the crystal amount and the rigid amorphous amount (Xc) are calculated by the equation (1). Here, ΔHm 0 is the heat of fusion of the crystalline polyamide, and its value is 229.76 J / g.

  The rigid amorphous amount (Xra) is calculated from the degree of crystallization (Xc) and the movable amorphous amount (Xma) according to equation (2). The movable amorphous amount (Xma) is calculated from the specific heat change (ΔCp) before and after the glass transition on the temperature-heat flow rate reversible curve by temperature modulation DSC method (TMDSC). Here, ΔCp uses the specific heat gap before and after the glass transition calculated by extrapolating the tangent to the temperature-heat flow reversible curve before and after the glass transition. The movable amorphous amount (Xma) is calculated by equation (3). Here, ΔCp 0 is the specific heat difference around the Tg of the amorphous polyamide, and the value is 0.4745 J / g ° C.

  The amount of rigid amorphous was calculated from the average value of two measurements of temperature modulation DSC and DSC.

Crystal amount: Xc (%) = (ΔHm-ΔHc) / ΔHm 0 × 100 (1)
Rigid amorphous amount: Xra (%) = 100-(Xc + Xma) (2)
Mobile amorphous amount: Xma (%) = ΔCp / ΔCp0 × 100 (3).

  Moreover, the measurement conditions of normal DSC and temperature modulation DSC were implemented on condition of the following.

(A) Normal DSC
Data processing was performed on Universal Analysis 2000 using TA Instrument Q1000. The measurement was performed under a nitrogen flow (50 mL / min) at a temperature range of 0 to 300 ° C., a temperature rising rate of 10 ° C./min, and a sample weight of about 5 mg (the thermal data is normalized by the weight after measurement).

  The details of the above-mentioned DSC method are described in the following [Document 1].

[Reference 1]
Wunderlich B. , Thermal Analysis of Polymeric Materials, Appendix 1 (The ATHAS Data Bank), Springer (2005).

(B) Temperature modulated DSC
Data processing was performed on Universal Analysis 2000 using TA Instrument Q1000. The measurement was carried out under a nitrogen flow (50 mL / min) at a temperature range of 0 to 200 ° C., a temperature rising rate of 2 ° C./min, and a sample weight of about 5 mg (calorimetric data are normalized by weight after measurement).

  This method is a method in which heating and cooling are repeated with a constant cycle and amplitude, and the temperature is averaged to measure, and the total DSC signal (Total Heat Flow) is reversible such as glass transition. It can be separated into components (Reversing Heat Flow) and irreversible components (Nonreversing Heat Flow) such as enthalpy relaxation, curing reaction, desolvation and the like. However, the melting peak of the crystal appears in both the reversible component and the irreversible component.

  The details of the above-mentioned temperature modulation DSC method are described in the above-mentioned [Document 1].

F. Evaluation of the race (a) Softness With respect to the race product, the softness of the experienced tester (5 persons) who has experienced the texture evaluation was relatively evaluated. As a result, the average value of the evaluation points of the respective inspectors is taken and rounded after the decimal point, and the average value is 5 for S, 4 for A, 3 for B, and 1-2 for C.

5 points: very good 4 points: slightly excellent 3 points: normal 2 points: slightly inferior 1 point: inferior.

  S and A were considered to be soft.

(B) Durability Burst strength is measured according to JIS L 1096-2010, Burst strength test method according to the Muren type method (Method A), and the burst strength at any three locations is measured, and from the average value, the following standard It rated four steps.

S: 130 kPa or more A: 100 kPa or more and less than 130 kPa B: 90 kPa or more and less than 100 kPa C: less than 90 kPa

  S and A were considered to be durable.

(C) Quality The race products were evaluated relative to the degree of dyeing spots on the inspectors (5 persons). As a result, the average value of the evaluation points of the respective inspectors is taken and rounded after the decimal point, and the average value is 5 for S, 4 for A, 3 for B, and 1-2 for C.

5 points: very excellent 4 points: slightly excellent 3 points: normal 2 points: slightly inferior 1 point: inferior S, A was regarded as a grade passing.

(D) Process Passability Knitting operation: The number of yarn breakages during knitting was indicated as the number of yarn breakage per lace fabric (80 m) according to the following criteria.

S: 0 or more and less than 5 A: 5 or more and less than 10 B: 10 or more and less than 20
C: 20 or more and less than 30
S and A were taken as process passability.

G. Evaluation of Stocking (a) Softness The stocking product was relatively worn on a human foot type, and the softness of the Lec part of an examiner (5 persons) who had experienced the evaluation of texture was relatively evaluated. As a result, the average value of the evaluation points of the respective inspectors is taken and rounded after the decimal point, and the average value is 5 for S, 4 for A, 3 for B, and 1-2 for C.

5 points: very excellent 4 points: slightly excellent 3 points: normal 2 points: slightly inferior 1 point: inferior S, A was regarded as a softness pass.

(B) Durability The stocking product is put on the outside in the form of a human foot and the garter is aligned at a position 60 cm from the heel to the thigh, and 52.5 cm from the heel to the thigh A circular mark is placed on the back of the foot-shaped thigh according to the size of the measurement frame centering on the position. When fixing the product to the measurement frame, the burst strength was measured in the same state as the worn state by fixing according to the circular mark attached earlier, and it was used as an indicator of durability.

  The burst strength was measured according to JIS L 1096-2010, the burst strength test method according to the Muren type method (method A), and the burst strength at any three places was measured, and four levels were evaluated based on the following criteria based on the average value.

S: 117.7 kPa or more A: 98.1 kPa or more and less than 117.7 kPa B: 88.3 kPa or more and less than 98.1 kPa C: less than 88.3 kPa

  S and A were considered to be durable.

(C) Quality The stocking product was relatively evaluated for the degree of dyeing spots on the examiner (5 persons). As a result, the decimal places of the average value of each examiner's evaluation point were rounded off, and the average value made 5 as S, 4 as A, 3 as B, and 1-2 as C.

5 points: very good 4 points: slightly excellent 3 points: normal 2 points: slightly inferior 1 point: inferior.

  S and A were graded.

(D) Process Passability With a sock knitting machine, the number of stops due to yarn breakage at the time of knitting was evaluated based on the following criteria when the stocking was continuously operated for 1 hour at a rotational speed of 400 rpm and knitting.

S: Less than 2 thread breaks,
A: Thread breakage 2 or more and less than 4 times,
B: Thread breakage 4 times or more and less than 6 times,
C: Thread breakage 6 times or more.

  S and A were taken as process passability.

Example 1
(Production of polyamide multifilament)
As a polyamide, a nylon 6 chip having a sulfuric acid relative viscosity (η r) of 3.3 and a melting point of 225 ° C. was dried by a conventional method so as to have a moisture content of 0.03 mass% or less. The obtained nylon 6 chip was melted at a spinning temperature (melting temperature) of 290 ° C., and was discharged from a spinneret. The spinneret used had a hole number of 42, a round shape, a hole diameter of φ0.25, and 6 yarns / die.

  The spinning machine was spun using a spinning machine (direct spinning and drawing machine) of the embodiment shown in FIG. The heating cylinder uses a heating cylinder length L of 50 mm and single-layer lengths L1 and L2 of 25 mm each, and the atmosphere temperature of the upper heating cylinder is 300 ° C. and the atmosphere temperature of the lower heating cylinder is 150 The temperature was set to be ° C.

  Each filament discharged from the spinneret is gradually cooled in a two-layer heating cylinder at an ambient temperature of 150 to 300 ° C., passed through a cold air ring cooling device with a cooling start distance of LS 169 mm, 18 ° C. Cool to solidify. Thereafter, an oil agent is applied at an oiling position Lg of 1300 mm from the spinneret surface, each filament is converged to form a multifilament, and entanglement is performed with a fluid entangled nozzle device, and then the take-up roller speed (spinning speed) 1500 m / min. The film was drawn at a draw ratio of 2.8 times via a drawing roller heated to a heat setting length of 600 mm at 155 ° C. and wound up to obtain a nylon 6 multifilament of 22.0 dtex and 7 filaments.

  The results of evaluation of the obtained nylon 6 multifilament are shown in Table 1.

(Manufacture of lace knitted fabric)
Next, the multifilament is warped and made with a runner length of 21.0 cm as a yarn on the back side of a 28G russell lace ground yarn, and further with a runner length of 100.0 cm as a yarn on the front side of the ground yarn and 235 to 330 dtex. Ed. Next, the inner fabric was obtained by scouring, dyeing and finishing the raw machine. The results of evaluation of the obtained race products are shown in Table 1.

Example 2
The atmosphere temperature of the upper heating cylinder is set to 300 ° C., the atmosphere temperature of the lower heating cylinder is set to 100 ° C., the atmosphere temperature is 100 to 300 ° C., the take-off roller speed is 1700 m / min. A 22 dtex, 7-filament nylon 6 multifilament was obtained and a lace knit was obtained in the same manner as in Example 1 except that the draw ratio was 2.7 times. The evaluation results are shown in Table 1.

[Example 3]
The atmosphere temperature of the upper heating cylinder is set to 300 ° C., the atmosphere temperature of the lower heating cylinder is set to 200 ° C., and the inside of the heating cylinder is slowly cooled at an atmosphere temperature of 200 to 300 ° C. A 22 dtex 7-filament nylon 6 multifilament was obtained and a lace knit was obtained in the same manner as in Example 1 except for the above. The evaluation results are shown in Table 1.

Example 4
A 22 dtex 7-filament nylon 66 multifilament is obtained and a lace knitted fabric is obtained in the same manner as in Example 1 except that the polyamide is a nylon 66 chip having a relative viscosity (ηr) of 3.2 and a melting point of 265 ° C. The The evaluation results are shown in Table 1.

Comparative Example 1
The heating cylinder was 22 dtex in the same manner as in Example 1 except that the heating cylinder length L was set to 50 ° C. using a single-layer heating cylinder, and the temperature was set to an atmosphere temperature of 300 ° C. , 7 filament nylon 6 multifilaments were obtained, and lace knits were obtained. The evaluation results are shown in Table 1.

  Because of the single-layer heating cylinder, the ambient temperature in the heating cylinder became constant, the heat convection in the heating cylinder was disturbed, and the U% deteriorated. In addition, since the ambient temperature setting in the heating cylinder is 300 ° C., which is a temperature close to the spinning temperature, orientation relaxation by slow cooling from the die surface to cooling is not sufficient, and the 15% strength is high. Therefore, it was inferior to the process passability, the grade, and the soft property of the lace knitted fabric.

Comparative Example 2
The atmosphere temperature of the upper heating cylinder is set at 200 ° C., and the atmosphere temperature of the lower heating cylinder is set at 100 ° C. The atmosphere temperature is 100 to 200 ° C., and the take-off roller speed is 1700 m / min. A 22 dtex 7-filament nylon 6 multifilament was obtained and a lace knit was obtained in the same manner as in Example 1 except for the above. The evaluation results are shown in Table 1.

  Since the ambient temperature setting in the heating cylinder is 100 to 200 ° C., which is 90 ° C. lower than the spinning temperature, orientation relaxation by slow cooling from the die surface to cooling is not sufficient, and the tensile elongation product, 15% strength is It was low. Therefore, it was inferior to the durability of the lace knit.

Comparative Example 3
A 22 dtex, 7-filament nylon 6 multifilament was obtained and a lace knit was obtained in the same manner as in Example 1 except that the heating cylinder was not installed. The evaluation results are shown in Table 1.

  Since the heating cylinder was not installed, the orientation relaxation by slow cooling from the die surface to cooling was insufficient, and the strength and elongation product and the 15% strength were low. Therefore, it was inferior to the durability of the lace knit.

[Example 5]
A nylon 6 multifilament of 22 dtex and 7 filaments was obtained by the same method as in Example 1 except that the feeding position Lg was 800 mm and the draw ratio was 3.0 times, and a lace knit was obtained. The evaluation results are shown in Table 2.

[Example 6]
A nylon 6 multifilament of 22 dtex and 7 filaments was obtained and a lace knit was obtained in the same manner as in Example 1 except that the feeding position Lg was 1500 mm and the draw ratio was 2.7 times. The evaluation results are shown in Table 2.

Comparative Example 4
A nylon 6 multifilament of 22 dtex and 7 filaments was obtained by the same method as in Example 1 except that the feeding position Lg was 600 mm and the draw ratio was 3.2 times, to obtain a lace knit. The evaluation results are shown in Table 2.

  Since the oil solution was applied while the filament temperature did not drop to room temperature, the U% deteriorated. In addition, the line bending from the cap face to the fueling guide was large, and the strength and elongation product and 15% strength were low due to the influence of the rubbing with the fueling guide. Therefore, it was inferior to the process passage property of a lace knit, durability, and a grade.

Comparative Example 5
A nylon 6 multifilament of 22 dtex and 7 filaments was obtained by the same method as in Example 1 except that the feeding position Lg was 3000 mm and the draw ratio was 2.7 times, and a lace knit was obtained. The evaluation results are shown in Table 2.

  The influence of yarn swaying by the downdraft is large, and the U% is deteriorated. In addition, due to the influence of the accompanying flow, the spinning tension increased and the spinning orientation advanced, so the strength and elongation product were low by 15%. Therefore, it was inferior to the grade and durability of a lace knit.

[Example 7]
A 22 dtex, 7 filaments nylon 6 multifilament was obtained and a lace knit was obtained in the same manner as in Example 1 except that the take-up roller speed (spinning speed) was 1000 m / min and the draw ratio was 3.8 times. The evaluation results are shown in Table 2.

Example 8
A nylon 6 multifilament of 22 dtex and 7 filaments was obtained by the same method as Example 1 except that the take-up roller speed (spinning speed) was 2000 m / min, and the draw ratio was 2.3 times, to obtain a lace knit. The evaluation results are shown in Table 2.

Comparative Example 6
A 22 dtex 7-filament nylon 6 multifilament was obtained and a lace knit was obtained in the same manner as in Example 1 except that the take-up roller speed (spinning speed) was 800 m / min and the draw ratio was 4.5 times. The evaluation results are shown in Table 2.

  Since the spinning speed was low, the spinning tension was low, the influence of the yarn fluctuation was large, and the U% deteriorated. In addition, the slow cooling effect of the heating tube became large, and strain relaxation of the polyamide molecular chain progressed too much, and the strength was 15% high. Therefore, it was inferior to the process passability, the grade, and the soft property of the lace knitted fabric.

Comparative Example 7
A nylon 6 multifilament of 22 dtex and 7 filaments was obtained by the same method as in Example 1 except that the take-up roller speed (spinning speed) was 2500 m / min and the draw ratio was 1.9 times, to obtain a lace knit. The evaluation results are shown in Table 2.

  Since the spinning speed was high, the strain rate was high, the variation in strain rate was increased, the draft unevenness was increased, and the U% was deteriorated. In addition, the slow cooling effect of the heating tube was low, strain relaxation of the polyamide molecular difference was insufficient, and the strength and elongation product was low at 15% strength. Therefore, it was inferior to the grade and durability of a lace knit.

[Example 9]
A nylon 6 multifilament of 22 dtex and 7 filaments was obtained and a lace knit was obtained in the same manner as in Example 1 except that draw rollers having different diameters were used and the heat setting length was 1200 mm. The evaluation results are shown in Table 2.

Comparative Example 8
A nylon 6 multifilament of 22 dtex and 7 filaments was obtained and a lace knit was obtained in the same manner as in Example 1 except that stretching rollers having different diameters were used and the heat setting length was set to 1800 mm. The evaluation results are shown in Table 2.

  The crystallization of the fiber by heat progressed too much, and the 15% strength was high. Therefore, it was inferior to the process passability of a lace knit and soft property.

[Example 10]
(Production of polyamide multifilament)
As a polyamide, a nylon 6 chip having a sulfuric acid relative viscosity (η r) of 3.3 and a melting point of 225 ° C. was dried by a conventional method so as to have a moisture content of 0.03 mass% or less. The obtained nylon 6 chip was melted at a spinning temperature (melting temperature) of 290 ° C., and was discharged from a spinneret. As the spinneret, one having a hole number of 30, a round shape, a hole diameter of 0.20, and 6 threads / base was used.

  The spinning machine was spun using the spinning machine of the embodiment shown in FIG. The heating cylinder uses a heating cylinder length L of 50 mm and single-layer lengths L1 and L2 of 25 mm each, and the atmosphere temperature of the upper heating cylinder is 300 ° C. and the atmosphere temperature of the lower heating cylinder is 150 The temperature was set to be ° C.

  Each filament discharged from the spinneret is gradually cooled in a two-layer heating cylinder at an ambient temperature of 150 to 300 ° C., passed through a cold air ring cooling device with a cooling start distance of LS 169 mm, 18 ° C. Cool to solidify. Thereafter, an oil agent is applied at an oiling position Lg of 1300 mm from the spinneret surface, each filament is converged to form a multifilament, and entanglement is performed with a fluid entangled nozzle device, and then the take-up roller speed (spinning speed) 1500 m / min. The film was drawn at a draw ratio of 2.6 times through a drawing roller heated to a heat setting length of 600 mm and 155 ° C. and wound up to obtain a nylon 6 multifilament of 8.0 dtex and 5 filaments.

  The results evaluated for the obtained nylon 6 multifilament are shown in Table 3.

(Manufacture of stocking)
Next, the multifilament is used as a covering yarn of covering yarn, a polyurethane elastic yarn of 22 dtex is used as a core yarn, draft is set to 3.0 times, and single covering is performed at a twist number of 2400 t / m (S, Z direction). , Single covered elastic yarn (SCY).

  Using the obtained SCY, it was knitted with a sock knitting machine. Next, the raw hen was refined, dyed, and final set at 120 ° C. for 30 seconds to obtain pantyhose products. The results of evaluation of the leg portion of the obtained pantyhose product are shown in Table 3.

Comparative Example 9
A nylon 6 multifilament of 8 dtex and 5 filaments was obtained and a stocking product was obtained in the same manner as in Example 10 except that the heating cylinder was not installed. The evaluation results are shown in Table 3.

  Since the heating cylinder was not installed, the orientation relaxation by slow cooling from the die surface to cooling was insufficient, and the strength and elongation product and the 15% strength were low. Therefore, the durability of the stocking product was inferior.

Comparative Example 10
A nylon 6 multifilament of 8 dtex and 5 filaments is obtained by the same method as in Example 10 except that the heating roller is not installed, the take-up roller speed (spinning speed) is 2500 m / min, and the draw ratio is 1.5 times. I got The evaluation results are shown in Table 3.

  Since the spinning speed is high, the strain rate is increased, so that the variation in strain rate is increased, the draft stretching unevenness is increased, and the U% is deteriorated. Moreover, since the heating cylinder was not installed, distortion relaxation by slow cooling from a nozzle face to cooling was insufficient, and 15% strength and strength and elongation product were low. Therefore, the quality and durability of the stocking product were inferior.

Comparative Example 11
The heating cylinder uses a single-layer heating cylinder with a heating cylinder length L of 50 mm, the temperature is set so that the atmosphere temperature is 300 ° C., the oiling position Lg is 3000 mm, the take-off roller speed (spinning speed) 600 m / min, the draw ratio 4 In the same manner as in Example 10 except that .5 times was used, a nylon 6 multifilament of 8 dtex and 5 filaments was obtained to obtain a stocking product. The evaluation results are shown in Table 3.

  Due to the single-layer heating cylinder, the ambient temperature distribution in the heating cylinder becomes constant, the heat convection in the heating cylinder is disturbed, and furthermore, the oiling position is low (the distance from the nozzle to oiling is long) and the spinning speed is low. The influence of yarn swaying was large and U% deteriorated. In addition, since the spinning speed is low, the slow cooling effect of the heating cylinder is increased, strain relaxation of the polyamide molecular chain proceeds too much, and further, crystallization of the fiber due to heat setting length too much, and the 15% strength is high. Therefore, it was inferior to the process passability, the grade, and the softness of a stocking product.

1: Spinneret 2: Gas jet device 3: Heating cylinder 4: Cooling device 5: Oiling device 6: Fluid entanglement nozzle device 7: Take-up roller 8: Stretching roller 9: Winding device L: Multilayer heating cylinder length L1: Multilayer Single layer length LS of heating cylinder: Cooling start distance Lg: Refueling position

Claims (6)

A polyamide multifilament characterized in that the tensile strength at 15% elongation is 4.0 to 6.0 cN / dtex, the strength and elongation product is 10.0 or more, and the yarn spots (U%) are 1.2 or less. The polyamide multifilament according to claim 1, wherein the single yarn fineness is 1.3 to 3.4 dtex. The polyamide multifilament according to claim 1 or 2, which has an elongation of 30 to 50%. The polyamide multifilament according to any one of claims 1 to 3, wherein the sum of the crystalline amount and the rigid amorphous amount is 70 to 90%. A lace knit using the polyamide multifilament according to any one of claims 1 to 4 as a lace base yarn. A stocking using the polyamide multifilament according to any one of claims 1 to 4 as a covering coated yarn, and partially using the covering yarn.