Nylon 66 fully-drawn yarn and preparation method thereof

Abstract

The invention discloses a chinlon 66 fully-drawn yarn and a preparation method thereof, which mainly comprises the following steps of: melting chinlon 66 slices, introducing into a spinning manifold, feeding into a spinning assembly, discharging by a spinneret plate, cooling, oiling, interlacing, drawing and shaping, winding, arranging a suction device at the outlet of the spinneret plate, and drawing at the air speed of 0.20-0.60 m / s to obtain the chinlon 66 fully-drawn yarn. The content of oligomer and monomer in the chinlon 66 fully drawn yarn is less than 1.00 wt%. The chinlon 66 fully-drawn yarn prepared by the method is low in oligomer and monomer content, high in strength and excellent in wear resistance.

Description

Technical Field

[0001] The present invention relates to a nylon 66 fully drawn yarn, and more specifically, to a nylon 66 fully drawn yarn with low oligomer and monomer content, high strength, and good wear resistance, and a preparation method thereof. Background Art

[0002] With the improvement of living standards, people's requirements for the appearance and performance of clothing are gradually increasing. Fine-denier fiber fabrics have the characteristics of excellent drape, soft feel, and comfortable wearing, and are deeply loved by consumers.

[0003] Polyamide fibers possess excellent mechanical and chemical properties and are widely used in clothing, decoration, automotive, and other fields. While nylon 6 currently accounts for a high proportion of clothing applications, nylon 66 has broad prospects for future clothing applications due to its superior wear resistance, heat resistance, and skin-friendliness.

[0004] Chinese patent CN101871134A discloses a fine-denier nylon 66 fully drawn fiber spinning process. Dry nylon 66 chips are heated, extruded, melted and held, loaded into a sand cup, subjected to high-pressure spinning, bundled and oiled, webbed, and drawn to form a fiber tow. The tow then passes through a spinning shaft and, after being drawn through a winding web, is wound into a yarn cake to produce fine-denier nylon 66 fully drawn fibers with a fineness of 11.2 dtex and a strength of 5.2 cN / dtex. However, the presence of oligomers and monomers in nylon 66 results in unstable quality of the resulting fully drawn nylon 66 fibers, particularly when made into fine-denier fibers whose strength does not meet high standards. Summary of the Invention

[0005] The object of the present invention is to provide a fine-denier nylon 66 fully drawn yarn with low oligomer and monomer content, high strength and good wear resistance, and a preparation method thereof.

[0006] The technical solutions of the present invention are as follows:

[0007] The nylon 66 fully drawn yarn has an oligomer and monomer content of less than 1.00 wt%; the fully drawn yarn has a strength of more than 6.50 cN / dtex and a wear resistance of more than level 4.

[0008] The fineness of the fully drawn yarn is preferably below 22 dtex.

[0009] The present invention also discloses a method for preparing the above-mentioned nylon 66 fully drawn yarn, which mainly comprises the following steps: melting nylon 66 slices and introducing them into a spinning box, and then feeding them into a spinning assembly. After being discharged from a spinneret, the slices are cooled, oiled, interlaced, drawn and shaped, and then wound to obtain the nylon 66 fully drawn yarn; a suction device is provided at the outlet of the spinneret, and the suction wind speed is 0.20 to 0.60 m / s.

[0010] The moisture content of the nylon 66 chips is preferably below 800 ppm.

[0011] The spinning beam temperature is preferably 280-290° C., and the draft ratio of the draft setting is preferably 1.70-2.50.

[0012] The present invention controls the content of oligomers and monomers in the nylon 66 fully drawn yarn, so that the nylon 66 fully drawn yarn has high strength and good wear resistance. The resulting fabric has high strength, friction resistance, and excellent dimensional stability. It is suitable for general clothing fields such as stockings, underwear, sportswear, etc., and has a very broad market prospect. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the suction device. DETAILED DESCRIPTION

[0014] The catalyst added during the polymerization reaction of nylon 66, the byproducts generated, the low-molecular-weight substances formed by molecular chain breakage during melt spinning, and the residual monomers (hexamethylenediamine and adipic acid) together constitute the oligomers and monomers described in this invention. These oligomers and monomers are substances soluble in boiling water, primarily including ethylpyrrolidine, cyclopentanone, hexamethylenediamine adipamide, hexamethylenediamine, and adipic acid.

[0015] These oligomers and monomers will cause the quality of the nylon 66 fully drawn yarn to be unstable and the strength to be substandard. In particular, the strength of the fine denier fiber produced is low and cannot meet the requirements of clothing applications.

[0016] In order to obtain high-strength nylon 66 fully drawn yarn, the present invention limits the oligomer and monomer content in the fully drawn yarn to below 1.00wt%. If the oligomer and monomer content in the fully drawn yarn is greater than 1.00wt%, the tensile strength and wear resistance of the fully drawn yarn will be reduced.

[0017] To meet clothing material requirements, the fineness of the nylon 66 fully drawn yarn can be anywhere between 5 dtex and 60 dtex. The smaller the fineness of the fully drawn yarn, the better the drape, hand feel, and wearing comfort of the fabric made therefrom. In the present invention, the fineness of the nylon 66 fully drawn yarn is preferably 22 dtex or less. The fineness refers to the total fineness of the nylon 66 fully drawn yarn multifilament.

[0018] By controlling the oligomer and monomer content in the nylon 66 fully drawn yarn to below 1.00 wt%, the strength and abrasion resistance of the fully drawn yarn can be effectively improved. Even when using fine denier fibers with a fineness of less than 22 dtex, the strength can reach above 6.50 cN / dtex and the abrasion resistance can reach above level 4.

[0019] The present invention does not impose any particular limitation on the preparation method of the nylon 66 fully drawn yarn, as long as the fully drawn yarn reaches the content of the oligomers and monomers. One of the methods is described below by way of example.

[0020] The preparation method is similar to that of the usual nylon 66 fully drawn yarn. It mainly involves melting the dried nylon 66 chips and introducing them into the spinning box. They are then sent into the spinning assembly. After being spit out from the spinneret, they are cooled, oiled, interlaced, drawn and shaped, and then wound to obtain the nylon 66 fully drawn yarn.

[0021] Specifically, nylon 66 chips are first transferred to a storage tank filled with dry nitrogen. Then, they are extruded and melted using a screw extruder to produce a nylon 66 melt. The nylon 66 melt is then introduced into a spinning manifold, metered by a metering pump, and fed into a spinning assembly, where it is ejected from a spinneret to form yarn. The spun yarn undergoes suction from a suction device, cooling and shaping using a side-blowing device, bundling and oiling using an oiling device, intertwining with an intertwining nozzle, and drawing and shaping using a drafting roller. Finally, it is wound into a yarn roll on a winder to form fully drawn nylon 66 fiber.

[0022] Some of the oligomers and monomers with lower boiling points in nylon 66 will volatilize due to the high temperature during the spinning process, fly out of the spinning assembly together with the spun yarn spun from the spinneret, and float in the air. As the temperature drops, the oligomers and monomers condense. Some of the condensed oligomers and monomers fall onto the spun yarn and adhere to the surface of the spun yarn or penetrate into the fiber, causing frequent floating and broken yarns, which is not conducive to drawing and shaping, and ultimately the strength of the fully drawn yarn is low.

[0023] To reduce the content of oligomers and monomers in fully drawn yarns, the present invention incorporates a suction device at the spinneret outlet to extract the oligomers and monomers volatilized during the spinning process. The suction device has a suction velocity of 0.20 to 0.60 m / s. When the suction velocity is lower than 0.20 m / s, oligomer and monomer removal is ineffective, failing to effectively improve spinnability and the strength of the fully drawn yarn. When the suction velocity is higher than 0.60 m / s, yarn jitter increases, affecting spinnability.

[0024] The presence of moisture causes hydrolysis of nylon 66 chips, resulting in a decrease in molecular weight and an increase in oligomer and monomer content, which in turn reduces the mechanical properties of the fully drawn yarn. During the forming process, moisture can also cause surface defects such as bubbles, silver streaks, and streaking in the fully drawn yarn, affecting wear resistance and causing the resulting yarn to have a high level of hairiness. Therefore, nylon 66 chips must be thoroughly dried before spinning. The lower the moisture content of the nylon 66 chips, the better the mechanical properties and wear resistance of the fully drawn yarn. In the present invention, the moisture content of the nylon 66 chips is preferably below 800 ppm.

[0025] If the spinning beam temperature is too low, the melt viscosity will be too high, increasing the shear stress of the melt in the spinneret, causing melt fracture, which in turn affects the strength of the fully drawn fiber. If the spinning beam temperature is too high, the polymer will crack, producing new oligomers and monomers, reducing spinnability and resulting in more hairiness in the resulting yarn. The spinning beam temperature of the present invention is preferably 280-290°C.

[0026] The draw ratio of the draw setting method of the present invention is preferably 1.70 to 2.50. If the draw ratio is too low, the molecular orientation of the fully drawn yarn is insufficient and the strength cannot reach the target; if the draw ratio is too high, the over-straightened molecular chains will break, resulting in problems such as broken yarn and hairiness.

[0027] The present invention obtains nylon 66 fully drawn yarn with good spinnability, high strength and good wear resistance by reducing the content of oligomers and monomers.

[0028] The testing method involved in the present invention is as follows:

[0029] (1) Strength and elongation

[0030] Tested according to standard GB / T 14344.

[0031] (2) Wire breakage rate

[0032] The yarn breakage rate refers to the number of yarn breaks that occur within 12 hours of spinning. Fewer yarn breaks indicate better spinnability, while more yarn breaks indicate poorer spinnability. No yarn breaks within 12 hours is considered excellent and marked with a circle; one yarn break within 12 hours is considered good and marked with a triangle; two or more yarn breaks within 12 hours is considered poor and marked with an x.

[0033] (3) Wear resistance

[0034] (a) Knitting

[0035] Circular knitting was performed on a 28-needle forming circular knitting machine (manufacturer: SANTONI) using 8 composite processed yarns (number of needles: 1440, speed: 16 rpm, designed weight: 140 g / m2).

[0036] (b) Refining

[0037] Prepare the refining agent solution (use soft water, add 2g / L of refining agent, and stir evenly), then put the woven fabric and refining agent solution into the dyeing machine according to the bath ratio of 1:30, and keep it at 80℃ for 20 minutes to complete the refining.

[0038] (c) Dyeing and setting

[0039] Prepare the dye solution (mix 2g / L leveling agent and 2g / L polyester dyeing acid in soft water to form an auxiliary solution. Next, add 3.0 owf% black disperse dye to the auxiliary solution, based on the weight of the fabric, and stir to form a dye solution). The scourable fabric and dye solution are placed in a dyeing machine at a bath ratio of 1:30 and held at 130°C for 45 minutes. Then, mix 0.5g / L sodium dithionite reducing agent in soft water and place this in the dyeing machine along with the dyed fabric. After holding at 80°C for 20 minutes to reduce and clean any loose colors, dyeing is complete. Finally, place the dyed fabric in a fabric setting machine at 160°C for 1 minute to set the fabric.

[0040] (d) Wear resistance test

[0041] The test was conducted according to JIS L1096:2010E. The specific method is as follows: Two 38mm diameter test pieces of the woven fabric sample were placed on a Martindale pressure testing machine. A pressure of 9.0±0.2kPa was applied, and the two test pieces were rubbed against each other along a predetermined trajectory 10,000 times. After removal, the two test pieces were then color-judged according to the JIS L0804 color standard, with grades 1, 2, 3, 4, and 5 being used. Higher grades indicate better abrasion resistance. The final result was the average of the grades of the two samples.

[0042] (4) Oligomer and monomer content

[0043] B.1 Instruments and Equipment

[0044] Analytical balance, small flask, drying oven, oil extraction device, oligomer and monomer extraction device, vacuum dryer

[0045] B.2 Test method

[0046] B.2.1 Take 5g of sample and remove moisture using a vacuum dryer.

[0047] B.2.2 Accurate weighing (W3),

[0048] B.2.3 Use oil extraction equipment to remove oil.

[0049] B.2.4 Boil in boiling water for more than 4 hours (water-bath ratio of 1:200 or more) to remove oligomers and monomers.

[0050] B.2.5 Rinse with running water, squeeze dry and dry in an oven at 105℃ for 2 hours.

[0051] B.2.6 Place in a vacuum drying oven for more than 6 hours, then cool, weigh (W4), and calculate.

[0052] B.3 Calculation of test results

[0053]

[0054] W1: empty flask weight,

[0055] W3: empty bottle + sample weight after dehydration,

[0056] W4: Weight of empty bottle + oligomer and monomer extracted.

[0057] (5)Hairiness

[0058] 100 silk reels were selected, each weighing 1 kg. If all the silk reels had no hairiness, they were judged as excellent and marked with ○; if 1 to 2 silk reels had hairiness, they were judged as good and marked with △; if more than 3 silk reels had hairiness, they were judged as poor and marked with ×.

[0059] (6) Slice moisture content

[0060] Tested according to standard GB / T 14190.

[0061] The present invention will be described in detail below with reference to the following examples and comparative examples. The present invention is not limited to the following examples.

[0062] Example 1:

[0063] Nylon 66 chips with a moisture content of 600 ppm after drying were extruded and melted through a screw extruder and introduced into a spinning manifold at a temperature of 285°C. The molten polymer was metered by a metering pump and fed into the spinning assembly. It was then discharged through a spinneret with a suction wind speed set at the spinneret outlet of 0.20 m / s. Finally, after cooling, oiling, interlacing, and drawing and shaping, it was wound to obtain a fully drawn nylon 66 yarn with a total fineness of 6 dtex and 5 single filaments. The drawing ratio of the drawing and shaping was 2.10. The oligomer and monomer content of the fully drawn nylon 66 yarn was 0.95% by weight, the strength was 6.69 cN / dtex, the abrasion resistance was graded as 4.5, the broken yarn rate was excellent, and the hairiness was judged as excellent. Specific values ​​are shown in Table 1.

[0064] Example 2:

[0065] Nylon 66 chips with a moisture content of 600 ppm after drying were extruded and melted through a screw extruder and introduced into a spinning manifold at a temperature of 285°C. The molten polymer was metered by a metering pump and fed into the spinning assembly before being expelled through a spinneret with a suction air velocity of 0.60 m / s set at the spinneret outlet. Finally, after cooling, oiling, interlacing, and drafting, the yarn was wound to obtain a fully drawn nylon 66 yarn with a total fineness of 6 dtex and 5 single filaments. The draft ratio for the drafting was 2.10. The fully drawn nylon 66 yarn contained 0.72% oligomer and monomer content by weight, a strength of 6.75 cN / dtex, a wear resistance of 5.0, an excellent yarn breakage rate, and excellent hairiness. Specific values ​​are shown in Table 1.

[0066] Example 3:

[0067] Nylon 66 chips with a moisture content of 600ppm after drying were extruded and melted through a screw extruder and introduced into a spinning manifold at a temperature of 285°C. The molten polymer was metered by a metering pump and fed into the spinning assembly, where it was then discharged through a spinneret with a suction wind speed set at the spinneret outlet of 0.40m / s. Finally, after cooling, oiling, interlacing, and drawing and shaping, the yarn was wound to obtain a fully drawn nylon 66 yarn with a total fineness of 6dtex and 5 single filaments. The drawing ratio of the drawing and shaping was 2.10. The oligomer and monomer content of the fully drawn nylon 66 yarn was 0.78wt%, the strength was 6.74cN / dtex, the abrasion resistance was graded 5.0, and the broken yarn rate and hairiness were both judged to be excellent. Specific values ​​are shown in Table 1.

[0068] Example 4:

[0069] Nylon 66 chips with a moisture content of 900ppm after drying are extruded and melted through a screw extruder and introduced into a spinning manifold at a temperature of 285°C. The molten polymer is metered by a metering pump and fed into the spinning assembly, and then discharged through the spinneret. The suction wind speed set at the spinneret outlet is 0.40m / s. Finally, after cooling, oiling, interlacing, drawing and shaping, the yarn is wound to obtain a nylon 66 fully drawn yarn with a total fineness of 6dtex and 5 single filaments. The drawing ratio of the drawing and shaping is 2.10. The oligomer and monomer content of the nylon 66 fully drawn yarn is 0.80wt%, the strength is 6.33cN / dtex, the wear resistance is level 4.0, the broken yarn rate is good, and the appearance of hairiness is good. Specific values ​​are shown in Table 1.

[0070] Example 5:

[0071] Nylon 66 chips with a moisture content of 600 ppm after drying were extruded and melted through a screw extruder and introduced into a spinning manifold at a temperature of 280°C. The molten polymer was metered by a metering pump and fed into the spinning assembly before being expelled through a spinneret with a suction air velocity of 0.40 m / s set at the spinneret outlet. Finally, after cooling, oiling, interlacing, and drafting, the yarn was wound to obtain a fully drawn nylon 66 yarn with a total fineness of 6 dtex and 5 single filaments. The draft ratio for the drafting was 2.10. The fully drawn nylon 66 yarn contained 0.76% oligomer and monomer content by weight, a strength of 6.60 cN / dtex, a wear resistance of 4.5, an excellent yarn breakage rate, and excellent hairiness. Specific values ​​are shown in Table 1.

[0072] Example 6:

[0073] Nylon 66 chips with a moisture content of 600 ppm after drying were extruded and melted through a screw extruder and introduced into a spinning manifold at a temperature of 290°C. The molten polymer was metered by a metering pump and fed into the spinning assembly, where it was then discharged through a spinneret with a suction wind speed set at 0.40 m / s. Finally, after cooling, oiling, interlacing, and drawing and shaping, the yarn was wound to obtain a fully drawn nylon 66 yarn with a total fineness of 6 dtex and 5 single filaments. The drawing ratio of the drawing and shaping was 2.10. The oligomer and monomer content of the fully drawn nylon 66 yarn was 0.82 wt%, the strength was 6.73 cN / dtex, the abrasion resistance was graded 5.0, the yarn breakage rate was excellent, and the hairiness was judged to be excellent. Specific values ​​are shown in Table 1.

[0074] Example 7:

[0075] Nylon 66 chips with a moisture content of 600ppm after drying were extruded and melted through a screw extruder and introduced into a spinning manifold at a temperature of 275°C. The molten polymer was metered by a metering pump and fed into the spinning assembly, where it was then expelled through a spinneret with a suction wind speed of 0.40m / s set at the spinneret outlet. Finally, after cooling, oiling, interlacing, and drawing and shaping, the yarn was wound to obtain a fully drawn nylon 66 yarn with a total fineness of 6dtex and 5 single filaments. The drawing ratio of the drawing and shaping was 2.10. The oligomer and monomer content of the fully drawn nylon 66 yarn was 0.75wt%, the strength was 6.44cN / dtex, the abrasion resistance was graded 4.0, the yarn breakage rate was good, and the hairiness was judged to be excellent. Specific values ​​are shown in Table 1.

[0076] Example 8:

[0077] Nylon 66 chips with a moisture content of 600ppm after drying are extruded and melted through a screw extruder and introduced into a spinning manifold at a temperature of 295°C. The molten polymer is metered by a metering pump and fed into the spinning assembly, and then discharged through the spinneret. The suction wind speed set at the spinneret outlet is 0.40m / s. Finally, after cooling, oiling, interlacing, drawing and shaping, the yarn is wound to obtain a nylon 66 fully drawn yarn with a total fineness of 6dtex and a single yarn number of 5. The drawing ratio of the drawing and shaping is 2.10. The oligomer and monomer content of the nylon 66 fully drawn yarn is 0.85wt%, the strength is 6.78cN / dtex, the wear resistance is level 5.0, the broken yarn rate is good, and the appearance of the hairiness is good. Specific values ​​are shown in Table 1.

[0078] Example 9:

[0079] Nylon 66 chips with a moisture content of 600 ppm after drying were extruded and melted through a screw extruder and introduced into a spinning manifold at a temperature of 285°C. The molten polymer was metered by a metering pump and fed into the spinning assembly. It was then discharged through a spinneret with a suction air velocity set at the spinneret outlet of 0.40 m / s. Finally, after cooling, oiling, interlacing, and drawing and shaping, it was wound to obtain a fully drawn nylon 66 yarn with a total fineness of 6 dtex and 5 single filaments. The drawing ratio of the drawing and shaping was 1.70. The oligomer and monomer content of the fully drawn nylon 66 yarn was 0.80 wt%, the strength was 6.55 cN / dtex, the abrasion resistance was graded 4.5, and the broken yarn rate and hairiness were both judged to be excellent. Specific values ​​are shown in Table 1.

[0080] Example 10:

[0081] Nylon 66 chips with a moisture content of 600 ppm after drying were extruded and melted through a screw extruder and introduced into a spinning manifold at a temperature of 285°C. The molten polymer was metered by a metering pump and fed into the spinning assembly before being expelled through a spinneret with a suction air velocity of 0.40 m / s set at the spinneret outlet. Finally, after cooling, oiling, interlacing, and drafting, the yarn was wound to obtain a fully drawn nylon 66 yarn with a total fineness of 6 dtex and 5 single filaments. The draft ratio for the drafting was 2.50. The fully drawn nylon 66 yarn contained 0.79% oligomer and monomer content by weight, a strength of 6.92 cN / dtex, a wear resistance of 5.0, and excellent yarn breakage rate and hairiness. Specific values ​​are shown in Table 1.

[0082] Example 11:

[0083] Nylon 66 chips with a moisture content of 600ppm after drying were extruded and melted through a screw extruder and introduced into a spinning manifold at a temperature of 285°C. The molten polymer was metered by a metering pump and fed into the spinning assembly, where it was then discharged through a spinneret with a suction wind speed set at 0.40m / s. Finally, after cooling, oiling, interlacing, and drawing and shaping, the yarn was wound to obtain a fully drawn nylon 66 yarn with a total fineness of 6dtex and 5 single filaments. The drawing ratio of the drawing and shaping was 1.65. The oligomer and monomer content of the fully drawn nylon 66 yarn was 0.79wt%, the strength was 6.37cN / dtex, the abrasion resistance was graded 4.0, and the broken yarn rate and hairiness were both judged to be excellent. Specific values ​​are shown in Table 1.

[0084] Example 12:

[0085] The nylon 66 chips with a moisture content of 600ppm after drying are extruded and melted through a screw extruder and introduced into a spinning box with a box temperature of 285°C. The molten polymer is metered by a metering pump, fed into the spinning assembly, and then spitted out through the spinneret. The suction wind speed set at the spinneret outlet is 0.40m / s. Finally, after cooling, oiling, interlacing, stretching and shaping, the nylon 66 fully drawn yarn with a total fineness of 6dtex and a single yarn number of 5 is obtained. The stretching ratio of the stretching and shaping is 2.55. The content of oligomers and monomers in the nylon 66 fully drawn yarn is 0.80wt%, the strength is 7.10cN / dtex, the wear resistance is level 5.0, the broken yarn rate is good, and the appearance of hairiness is good. Specific values ​​are shown in the table

[0086] Example 13:

[0087] Nylon 66 chips with a moisture content of 600 ppm after drying were extruded and melted through a screw extruder and introduced into a spinning manifold at a temperature of 285°C. The molten polymer was metered by a metering pump and fed into the spinning assembly, where it was then discharged through a spinneret with a suction wind speed set at 0.40 m / s. Finally, after cooling, oiling, interlacing, and drawing and shaping, the yarn was wound to obtain a fully drawn nylon 66 yarn with a total fineness of 22 dtex and 5 single filaments. The drawing ratio for the drawing and shaping was 2.00. The oligomer and monomer content of the fully drawn nylon 66 yarn was 0.79% by weight, the strength was 6.60 cN / dtex, the abrasion resistance was graded 5.0, and the broken yarn rate and hairiness were both judged to be excellent. Specific values ​​are shown in Table 1.

[0088] Comparative Example 1:

[0089] Nylon 66 chips with a moisture content of 600ppm after drying are extruded and melted through a screw extruder and introduced into a spinning manifold at a temperature of 285°C. The molten polymer is metered by a metering pump and fed into the spinning assembly, then discharged through a spinneret with a suction wind speed of 0.10m / s set at the spinneret outlet. Finally, after cooling, oiling, interlacing, and drawing and shaping, they are wound to obtain a nylon 66 fully drawn yarn with a total fineness of 6dtex and 5 single filaments. The drawing ratio of the drawing and shaping is 2.10. The oligomer and monomer content of the nylon 66 fully drawn yarn is 1.10wt%, the strength is 6.28cN / dtex, the abrasion resistance is level 3.5, the broken yarn rate is good, and the appearance of hairiness is excellent. Specific values ​​are shown in Table 1.

[0090] Since the suction wind speed is too low, the removal effect of oligomers and monomers is poor, the content of oligomers and monomers in the fully drawn yarn is too high, and the strength and wear resistance are poor.

[0091] Comparative Example 2:

[0092] Nylon 66 chips with a moisture content of 600 ppm after drying were extruded and melted through a screw extruder and introduced into a spinning manifold at a temperature of 285°C. The molten polymer was metered by a metering pump and fed into the spinning assembly. It was then discharged through a spinneret with a suction wind speed set at the spinneret outlet of 0.65 m / s. Finally, after cooling, oiling, interlacing, and drawing and shaping, it was wound to obtain a fully drawn nylon 66 yarn with a total fineness of 6 dtex and 5 single filaments. The drawing ratio of the drawing and shaping was 2.10. The oligomer and monomer content of the fully drawn nylon 66 yarn was 0.68% by weight, the strength was 6.79 cN / dtex, the abrasion resistance was graded as 5.0, the broken yarn rate was good, and the hairiness was judged as excellent. Specific values ​​are shown in Table 1.

[0093] Because the suction wind speed is too high, the yarn jitter will increase, affecting the spinning performance.

[0094] Comparative Example 3:

[0095] Nylon 66 chips with a moisture content of 600 ppm after drying were extruded and melted through a screw extruder and introduced into a spinning manifold at a temperature of 285°C. The molten polymer was metered by a metering pump and fed into the spinning assembly. It was then discharged through a spinneret and finally cooled, oiled, entangled, and drawn and fixed before being wound to produce a fully drawn nylon 66 yarn with a total fineness of 6 dtex and 5 filaments. The draw ratio for the drawing and fixing was 2.10. The fully drawn nylon 66 yarn contained 1.42% oligomer and monomer content by weight, 5.98 cN / dtex strength, 3.0 abrasion resistance, poor filament breakage rate, and excellent hairiness. See Table 1 for specific values.

[0096] Since there is no suction device, the oligomers and monomers cannot be removed, and the content of oligomers and monomers in the fully drawn yarn is too high, resulting in poor spinnability, and the strength and wear resistance of the fully drawn yarn are also poor.

[0097]

Claims

1. Nylon 66 fully drawn yarn, characterized by: The content of oligomers and monomers in the fully drawn yarn is below 1.00 wt %; the strength of the fully drawn yarn is above 6.5 cN / dtex, and the wear resistance is above level 4.

2. The fully drawn nylon 66 yarn according to claim 1, characterized in that: The fineness of the fully drawn yarn is below 22 dtex.

3. The method for preparing the fully drawn nylon 66 yarn according to claim 1, comprising: melting nylon 66 chips, introducing them into a spinning manifold, feeding them into a spinning assembly, discharging them through a spinneret, cooling them, oiling them, entangled them, drawing and shaping them, and then winding them to obtain the fully drawn nylon 66 yarn; characterized in that: A suction device is provided at the outlet of the spinneret, and the suction wind speed is 0.20 to 0.60 m / s.

4. The method for preparing nylon 66 fully drawn yarn according to claim 3, characterized in that: The moisture content of the nylon 66 slices is below 800 ppm.

5. The method for preparing nylon 66 fully drawn yarn according to claim 3 or 4, characterized in that: The temperature of the spinning box is 280-290°C.

6. The method for preparing nylon 66 fully drawn yarn according to claim 3 or 4, characterized in that: The draft ratio of the draft setting is 1.70 to 2.50.

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