A high-strength and high-elongation polyamide 56 pre-oriented yarn and its preparation method and application

Abstract

The present invention provides a high-strength and high-elongation polyamide 56 pre-oriented yarn and a preparation method thereof. By optimizing the spinning process, such as increasing the spinning speed and selecting a suitable spinneret hole, the molecular chain directivity in the fiber spinning process is effectively improved, high-speed orientation induces crystallization, and the crystallization performance in the polyamide 56 spinning process is improved. The mechanical properties of the prepared polyamide 56 pre-oriented yarn are greatly improved, the prepared elasticized yarn breakage rate is low, and the polyamide 56 elasticized yarn has good fluffiness, good curling effect, and good dyeing performance.

Description

Technical Field

[0001] The invention relates to a high-strength and high-elongation polyamide 56 pre-oriented yarn and a preparation method and application thereof. Background Art

[0002] Polyamide fiber is one of the earliest synthetic fibers put into industrial production in the world, and plays a pivotal role in the field of synthetic fibers. There are many types of polyamide fibers, and the most widely used and industrially produced ones are polyamide 6 and polyamide 66. The main applications involve: socks, lace underwear, corsets, sports underwear, wedding dresses, casual jackets, sportswear, raincoats, assault jackets, quick-drying clothes, winter clothing, outdoor tents, sleeping bags, mountaineering bags and other fields; while industrial yarns are widely used in fields such as cords, transmission belts, hoses, ropes, fishing nets, tires, parachutes and so on.

[0003] Bio-based polyamide 56 fiber is a bio-based polyamide material obtained by using renewable bio-based raw materials, using biotechnology to prepare monomer raw materials, and then polymerizing them. The raw materials for the production of polyamide 56 fiber are made by biological methods, which are green materials, do not rely on petroleum resources, and do not cause serious pollution to the environment. It can also reduce carbon dioxide emissions and reduce the greenhouse effect. Compared with the existing petroleum-based polyamides on the market, in addition to the green and environmentally friendly raw materials and raw material processing, the material has better mechanical properties, moisture absorption and quick drying (the official moisture regain of 6% is closer to cotton, and the official moisture regain of ordinary polyamide is 4-5%), skin-friendly, wear-resistant and good softness, as well as low-temperature easy dyeing characteristics. The excellent performance of bio-based polyamide 56 is suitable for use in the textile field. It is currently widely used in the fields of civilian filaments, staple fibers, industrial yarns, continuous bulked filaments, monofilaments, etc.

[0004] At present, the spinning speed of pre-oriented yarn prepared from polyamide 6 and polyamide 66 is 4000-4200m / min, which is low, the fiber orientation is low, the mechanical properties of the prepared pre-oriented yarn are low, the yarn breakage rate is high during the texturing process, and the double A rate of the texturized yarn is low. Summary of the invention

[0005] In order to solve the problems existing in the existing polyamide pre-oriented yarns, the present invention optimizes the spinning process, such as increasing the spinning speed and selecting suitable spinneret holes, thereby effectively improving the molecular chain directivity during fiber spinning, high-speed orientation-induced crystallization, and improving the crystallization performance during the spinning process of polyamide 56. The mechanical properties of the prepared polyamide 56 pre-oriented yarns are greatly improved.

[0006] The first object of the present invention is to provide a high-strength and high-elongation polyamide 56 pre-oriented yarn, wherein the single-filament broken rate of the high-strength and high-elongation polyamide 56 pre-oriented yarn is ≤2 pieces / 24h, preferably ≤1 piece / 24h, and more preferably ≤0 pieces / 24h.

[0007] In some specific embodiments, the number of the polyamide 56 pre-oriented yarns is ≤2 per 12kg package, preferably ≤1 per 12kg package, and more preferably 0 per 12kg package.

[0008] In some specific embodiments, the polyamide 56 pre-oriented yarn production rate is ≥98%, preferably ≥99%, and more preferably ≥99.5%.

[0009] In some specific embodiments, the polyamide 56 pre-oriented yarn has a breaking strength of 3.6-5.0 cN / dtex, preferably 3.7-4.8 cN / dtex, and more preferably 3.9-4.6 cN / dtex; and a breaking strength variation coefficient (CV) %≤2%, preferably ≤1.5%, and more preferably ≤1.0%.

[0010] The elongation at break of the polyamide 56 oriented yarn is ≤90%, preferably ≤85%, more preferably ≤80%; the coefficient of variation (CV) of the elongation at break is ≤3.0%, preferably ≤2.0%, more preferably ≤1.5%.

[0011] The strand unevenness of the polyamide 56 oriented yarn is ≤1.5%, preferably ≤1.3%, and more preferably ≤1.0%.

[0012] The orientation factor of the polyamide 56 oriented yarn is ≥0.6, preferably ≥0.7, and more preferably ≥0.8.

[0013] In some specific embodiments, during the spinning process of the polyamide 56 pre-oriented yarn, the spinning speed is controlled to be ≥4400 m / min, preferably ≥4500 m / min, and more preferably ≥4600 m / min.

[0014] In some specific embodiments, the spinning speed is 4400-5500 m / min.

[0015] In some specific embodiments, the spinning speed is 4500-5000 m / min.

[0016] In some specific embodiments, the spinning speed is 4500-4700 m / min.

[0017] In some specific embodiments, during the spinning process of the polyamide 56 pre-oriented yarn, the spinneret draw ratio is controlled to be ≥160, preferably ≥180, and more preferably ≥200. In the present invention, the spinneret draw ratio is the ratio of the first godet speed to the fiber exiting spinneret speed during the fiber winding process.

[0018] In some specific embodiments, the spinneret stretch ratio is 160-500.

[0019] In some specific embodiments, the spinneret stretch ratio is 180-230.

[0020] In some specific embodiments, during the spinning process of the polyamide 56 pre-oriented yarn, the cooling wind speed is controlled to be 0.38-0.50 m / s, preferably 0.40-0.48 / s, and more preferably 0.42-0.46 / s; the wind temperature is 16-23°C, preferably 17-22°C, and more preferably 18-21°C; the wind humidity is 70-95%, preferably 75-90%, and more preferably 80-85%.

[0021] In some specific embodiments, during the spinning process of the polyamide 56 pre-oriented yarn, the side blowing height is controlled to be ≥140 cm, preferably ≥150 cm, and more preferably 160 cm-200 cm.

[0022] In some specific embodiments, during the spinning process of the polyamide 56 pre-oriented yarn, the oiling height is controlled to be 90-150 cm, preferably 100-140 cm, and more preferably 110-130 cm.

[0023] In some specific embodiments, during the spinning process of the polyamide 56 pre-oriented yarn, the oil concentration is controlled to be 0.4-0.5wt%, preferably 0.42-0.48wt%, and more preferably 0.44-0.46wt%.

[0024] In some specific embodiments, the oil used for oiling can be a commercially available polyamide pre-oriented yarn oil, such as DAKO oil, Takemoto oil, Kekai oil, Sima oil, and the like.

[0025] In some specific embodiments, the polyamide 56 pre-oriented yarn spinning process includes passing the polyamide 56 melt through a spinning assembly, extruding from a spinneret hole to form a spun yarn, and then cooling, oiling, and winding the spun yarn to obtain the polyamide 56 pre-oriented yarn.

[0026] The second object of the present invention is to provide a method for preparing high-strength and high-elongation polyamide 56 pre-oriented yarn, the preparation method comprising the following steps:

[0027] (1) providing a polyamide 56 melt;

[0028] (2) transporting the polyamide 56 melt to the spinning manifold through a melt pipe, and after being accurately metered by a metering pump, injecting the melt into the spinning assembly, and extruding the melt from the spinneret holes to form primary yarn;

[0029] (3) Cooling, oiling and winding the spun yarn, controlling the spinning speed to 4400-5500 m / min; controlling the spinneret stretching ratio to ≥160, preferably ≥180, more preferably ≥200; and obtaining the polyamide 56 oriented yarn.

[0030] In some specific embodiments, the polyamide 56 melt can be obtained by heating polyamide 56 resin chips to a molten state, or the polyamide 56 melt obtained by a continuous polymerization device is directly spun.

[0031] In some specific embodiments, the polyamide 56 melt is transported to the spinning manifold through a melt pipe, accurately metered by a metering pump, injected into the spinning assembly, and extruded from a spinneret to form primary filaments.

[0032] In some specific embodiments, the polyamide 56 resin or melt has a relative viscosity of 2.40-2.85, preferably 2.43-2.82, more preferably 2.45-2.78, such as 2.50, 2.72.

[0033] In some specific embodiments, the polyamide 56 resin chips are heated to a molten state by a screw to obtain a polyamide 56 melt, and the screw adopts four-zone heating, wherein the temperature of zone one is 250-280°C, preferably 260-275°C, for example, 270°C; the temperature of zone two is 260-285°C, preferably 265-280°C, for example, 280°C; the temperature of zone three is 270-290°C, preferably 275-285°C, for example, 285°C; the temperature of zone four is 275-295°C, preferably 280-290°C, for example, 280°C.

[0034] In some specific embodiments, the spinning beam temperature is 275-285°C, preferably 280-283°C, such as 280°C.

[0035] In some specific embodiments, the spinning assembly pressure is 13-20 MPa, preferably 15-18 MPa, such as 15 MPa.

[0036] In some specific embodiments, the winding is carried out between two guide wire discs, and the primary yarn first passes through the first guide wire disc, then to the second guide wire disc, and finally is wound into shape; wherein, the underfeeding between the first guide wire disc and the second guide wire disc is ≤20m / min, preferably ≤15m / min, preferably 5-20m / min, for example 10m / min; the overfeeding between the second guide wire disc and the winding head is ≤50m / min, preferably ≤30m / min, preferably 10-50m / min, for example 20m / min.

[0037] The third object of the present invention is to provide a polyamide 56 stretch yarn prepared from the above-mentioned high-strength and high-elongation polyamide 56 pre-oriented yarn, wherein the curling shrinkage rate of the polyamide 56 stretch yarn is ≥35%, preferably ≥40%, and more preferably ≥45%;

[0038] Curl stability ≥ 38%, preferably ≥ 42%, more preferably ≥ 46%;

[0039] The polyamide 56 stretch yarn has a breakage rate of ≤5%, preferably ≤3%, and more preferably ≤2%;

[0040] The dyeing double A ratio of the polyamide 56 stretch yarn is ≥96%, preferably ≥97%, and more preferably ≥98%.

[0041] In some specific embodiments, the preparation method of the polyamide 56 stretch yarn comprises the following steps: passing the high-strength and high-elongation polyamide 56 pre-oriented yarn through a yarn guide and a yarn cutter, and passing through a first roller; then sequentially stretching through a hot box, cooling through a cooling plate, setting at room temperature, false twisting, and passing through a second roller; then processing through a network nozzle, passing through a third roller, oiling, and winding to obtain the polyamide 56 stretch yarn;

[0042] Wherein, the temperature of the hot stretching is 140-200°C, and the multiple is 1.25-1.40; and / or, the false twist friction plate is a C-type disk, a D-type disk or a PU-type disk; and / or, the D / Y of the false twist is 1.6-2.2; and / or, the T2 processing tension of the false twist is controlled to be 0.8-1.1 times the T1 processing tension; the winding speed is 500-800m / min.

[0043] The present invention also provides an application of the above-mentioned pre-oriented yarn and elasticized yarn in the fields of knitted and woven fabrics, carpet yarns and blended yarns.

[0044] In the present invention, the pre-oriented yarn and the elasticized yarn fiber are used in knitted and woven fabrics in non-limiting applications including underwear, shirts, suits, yoga clothes, down jackets, jackets, socks, bags, curtains, shoes, embroidery threads, trademarks, sofa fabrics, work clothes, sportswear, elastic bands and other fields.

[0045] On the basis of being in accordance with the common sense in the art, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention. The reagents and raw materials used in the present invention are all commercially available.

[0046] The positive and progressive effects of the present invention are:

[0047] First, the raw material 1,5-pentanediamine for producing the polyamide 56 pre-oriented yarn provided by the present invention is made by a biological method, is a green material, does not rely on petroleum resources and does not cause serious pollution to the environment, and can reduce carbon dioxide emissions, reduce the generation of greenhouse effects, and adapt to the development trend of carbon neutrality.

[0048] Second, the preparation method of high-strength and high-elongation polyamide 56 pre-oriented yarn provided by the present invention effectively improves the molecular chain directivity during fiber spinning and induces crystallization through high-speed orientation by optimizing the spinning process, such as increasing the spinning speed and selecting a suitable spinneret hole diameter to increase the spinneret stretching ratio. At the same time, the spinning conditions are further optimized: adjusting the cooling wind speed, wind temperature, wind humidity, side blowing height, oiling height, oiling concentration, etc., to improve the crystallization performance of polyamide 56 during spinning, and the mechanical properties of the prepared polyamide 56 pre-oriented yarn are greatly improved.

[0049] Third, the polyamide 56 pre-oriented yarn provided by the present invention can be spun at high speed, and the spinning speed is preferably as high as 4400-5500m / min, and the elongation of the pre-oriented yarn can still meet the requirements of elasticization; using the same number of pre-oriented yarn spinning equipment, the output of the scheme of the present invention can be increased by 12wt%-19wt% compared with the output of polyamide 6 and polyamide 66, and the same output can reduce the investment in pre-oriented yarn spinning equipment, greatly saving production costs.

[0050] Fourth, the polyamide 56 pre-oriented yarn provided by the present invention has the high-quality characteristics of high orientation, high breaking strength, large elongation and low yarn unevenness. The prepared elastic yarn has a low breakage rate, and the polyamide 56 elastic yarn has good fluffiness, good curling effect and good dyeing performance.

[0051] Fifth, the polyamide 56 pre-oriented yarn and textured yarn provided by the present invention can be produced by using conventional polyamide 6 and polyamide 66 spinning and textured equipment, without the need to modify the spinning and textured equipment. The production rate can be improved by adjusting the spinning and textured process. DETAILED DESCRIPTION

[0052] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. The experimental methods in the following examples without specifying specific conditions are selected according to conventional methods and conditions, or according to the product specifications. The polyamide 56 resin was purchased from Cathay (Jinxiang) Biomaterials Co., Ltd.

[0053] Test method:

[0054] 1) Relative viscosity: by Ubbelohde viscometer concentrated sulfuric acid method: accurately weigh 0.25±0.0002g of dried polyamide slices, add 50mL concentrated sulfuric acid (96wt%) to dissolve; measure and record the concentrated sulfuric acid flow time t0 and the polyamide sample solution flow time t in a 25℃ constant temperature water bath. Viscosity calculation formula: relative viscosity = t / t0; t—solution flow time; t0—solvent flow time.

[0055] 2) Breaking strength, breaking strength variation coefficient (CV)%, breaking elongation, breaking elongation variation coefficient (CV)%: in accordance with GB / T 14344-2008 chemical fiber tensile properties test method; apply 0.05±0.005cN / dtex pre-tension, holding distance 250mm, stretching speed 1000mm / min.

[0056] 3) Orientation factor: measured by the sonic orientation instrument, take a section of fiber about 50cm long, hold it on the clip at the left end of the sonic orientation instrument, gently hang the fiber on the probes of the two detectors, and apply a pre-tension value of 0.1g / dpf on the right. Wait for the fiber to stabilize before starting the test. The double length method is used in the experiment. The mobile probe is first placed at 20cm and ten data are captured; then, it is moved to 40cm. Ten data are captured. After five tests for each group, the average value is taken.

[0057] 4) Strip unevenness: Uster Strip Evenness Tester, measured according to GB / T 14346-93 method.

[0058] 5) Fiber production rate: Production rate = (weight of finished fiber prepared / total weight of resin input) × 100%.

[0059] 6) Dyeing double A rate: Dyeing double A rate = ((weight of fibers with dyeing uniformity ≥ 4.5) / total weight of all dyed fibers) × 100%. Dyeing uniformity (gray card) / grade: FZ / T 50008 Nylon filament dyeing uniformity test method.

[0060] 7) Number of hairs: manually determined.

[0061] 8) Broken single filament: manual statistics.

[0062] 9) Wire breakage rate after stretching: manually calculated.

[0063] 10) Curl shrinkage and curl stability: in accordance with GB / T 6506.

[0064] Example 1

[0065] 1. The method for preparing polyamide 56 pre-oriented yarn comprises the following steps:

[0066] (1) heating polyamide 56 resin chips to a molten state through a screw to form a polyamide 56 melt for spinning;

[0067] (2) transporting the polyamide 56 melt to the spinning manifold through a melt pipe, and after being accurately metered by a metering pump, injecting the melt into the spinning assembly, and extruding the melt from the spinneret holes to form primary yarn;

[0068] (3) Cooling, oiling, and winding the spun yarn to obtain polyamide 56 pre-oriented yarn.

[0069] In step (1), the relative viscosity of the polyamide 56 resin is 2.72. The screw is heated in four zones, wherein the temperature of zone 1 is 270°C, the temperature of zone 2 is 280°C, the temperature of zone 3 is 285°C, and the temperature of zone 4 is 280°C.

[0070] In step (2), the spinning box temperature is 280° C. and the spinning assembly pressure is 15 MPa.

[0071] In step (3), the winding is carried out between two guide wire discs, and the spun yarn first passes through the first guide wire disc, then to the second guide wire disc, and finally is wound into shape. The underfeed between the first guide wire disc and the second guide wire disc is 10m / min, and the overfeed between the second guide wire disc and the winding head is 20m / min.

[0072] The spinning speed was controlled to be 4500 m / min; the stretching ratio of the polyamide 56 pre-oriented yarn spinneret was 180.

[0073] The cooling wind speed was controlled at 0.42 / s, the wind temperature was 18°C, and the wind humidity was 85%.

[0074] The side blowing height was controlled to be 160 cm, the oiling height was 120 cm, the oiling concentration was 0.45 wt %, and the oil agent was DAKO oil agent (concentration was 6 wt %).

[0075] The breaking strength, breaking elongation, unevenness, orientation factor, production rate, number of broken filaments and number of hairy filaments of polyamide 56 pre-oriented yarn were tested and statistically analyzed. The results are shown in Table 1.

[0076] 2. A method for preparing a polyamide 56 stretch yarn comprises the following steps:

[0077] The polyamide 56 pre-oriented yarn obtained in the above steps is passed through a yarn guide and a yarn cutter to the first roller, and then is heat-stretched in a hot box, and then cooled and shaped by a cooling plate, and a certain twist is obtained by a false twister, and then passed through a tension online detector, a second roller, and then a network nozzle to add a network, and then passed through a third roller, a broken wire sensor, and an oil tanker to add oil, and finally wound to obtain a polyamide 56 elastic yarn;

[0078] The friction plate used by the false twister is a C-type disk with a thickness of 6 mm, a spacing of 0.75 mm, and a friction coefficient of 0.65.

[0079] The temperature of the hot box is 180°C, the stretching ratio is 1.32, the D / Y ratio is 1.75, the T2 processing tension is controlled to be 0.95 of the T1 tension, and the winding speed is 600 m / min.

[0080] The curl shrinkage, curl stability, yarn breakage rate and dyeing double A rate of polyamide 56 stretch yarn were tested and statistically analyzed. The results are shown in Table 1.

[0081] Example 2

[0082] The preparation method of polyamide 56 pre-oriented yarn is the same as that in Example 1, except that the spinning speed is controlled to be 4600 m / min.

[0083] The preparation method of the polyamide 56 stretch yarn is the same as that in Example 1.

[0084] Example 3

[0085] The preparation method of polyamide 56 pre-oriented yarn is the same as that in Example 1, except that the spinning speed is controlled to be 4700 m / min.

[0086] The preparation method of the polyamide 56 stretch yarn is the same as that in Example 1.

[0087] Example 4

[0088] The preparation method of polyamide 56 pre-oriented yarn is the same as that in Example 1, except that the spinneret stretching ratio is controlled to be 200.

[0089] The preparation method of the polyamide 56 stretch yarn is the same as that in Example 1.

[0090] Example 5

[0091] The preparation method of polyamide 56 pre-oriented yarn is the same as that in Example 1, except that the spinneret stretching ratio is controlled to be 230.

[0092] The preparation method of the polyamide 56 stretch yarn is the same as that in Example 1.

[0093] Example 6

[0094] The method for preparing polyamide 56 pre-oriented yarn is the same as that in Example 1, except that the wind speed is controlled to be 0.48 m / s.

[0095] The preparation method of the polyamide 56 stretch yarn is the same as that in Example 1.

[0096] Example 7

[0097] The preparation method of polyamide 56 pre-oriented yarn is the same as that in Example 1, except that the air temperature is controlled at 21°C.

[0098] The preparation method of the polyamide 56 stretch yarn is the same as that in Example 1.

[0099] Example 8

[0100] The preparation method of polyamide 56 pre-oriented yarn is the same as that in Example 1, except that the air humidity is controlled to be 78%.

[0101] The preparation method of the polyamide 56 stretch yarn is the same as that in Example 1.

[0102] Example 9

[0103] The method for preparing polyamide 56 pre-oriented yarn is the same as that in Example 1, except that the side blowing height is controlled to be 140 cm.

[0104] The preparation method of the polyamide 56 stretch yarn is the same as that in Example 1.

[0105] Example 10

[0106] The preparation method of polyamide 56 pre-oriented yarn is the same as that in Example 1, except that the oiling height is controlled to be 95 cm.

[0107] The preparation method of the polyamide 56 stretch yarn is the same as that in Example 1.

[0108] Embodiment 11

[0109] The preparation method of polyamide 56 pre-oriented yarn is the same as that in Example 1, except that the relative viscosity of the polyamide 56 resin is 2.50.

[0110] The preparation method of the polyamide 56 stretch yarn is the same as that in Example 1.

[0111] Comparative Example 1

[0112] The preparation method of polyamide 56 pre-oriented yarn is the same as that in Example 1, except that the spinning speed is controlled to be 4000 m / min.

[0113] The preparation method of the polyamide 56 stretch yarn is the same as that in Example 1.

[0114] Comparative Example 2

[0115] The preparation method of polyamide 56 pre-oriented yarn is the same as that in Example 1, except that the spinning speed is controlled to be 4200 m / min.

[0116] The preparation method of the polyamide 56 stretch yarn is the same as that in Example 1.

[0117] Comparative Example 3

[0118] The preparation method of polyamide 56 pre-oriented yarn is the same as that in Example 1, except that the spinneret stretching ratio is controlled to be 120.

[0119] The preparation method of the polyamide 56 stretch yarn is the same as that in Example 1.

[0120] Comparative Example 4

[0121] The method for preparing polyamide 56 pre-oriented yarn is the same as that in Example 1, except that the wind speed is controlled to be 0.32 m / s.

[0122] The preparation method of the polyamide 56 stretch yarn is the same as that in Example 1.

[0123] Comparative Example 5

[0124] The preparation method of polyamide 56 pre-oriented yarn is the same as that in Example 1, except that the air temperature is controlled at 24°C.

[0125] The preparation method of the polyamide 56 stretch yarn is the same as that in Example 1.

[0126] Comparative Example 6

[0127] The preparation method of polyamide 56 pre-oriented yarn is the same as that in Example 1, except that the air humidity is controlled to be 65%.

[0128] The preparation method of the polyamide 56 stretch yarn is the same as that in Example 1.

[0129] Comparative Example 7

[0130] The method for preparing polyamide 56 pre-oriented yarn is the same as that in Example 1, except that the side blowing height is controlled to be 120 cm.

[0131] The preparation method of the polyamide 56 stretch yarn is the same as that in Example 1.

[0132] Comparative Example 8

[0133] The preparation method of polyamide 56 pre-oriented yarn is the same as that in Example 1, except that the oil concentration is controlled to be 0.35wt%.

[0134] The preparation method of the polyamide 56 stretch yarn is the same as that in Example 1.

[0135] Comparative Example 9

[0136] The preparation method of polyamide 56 pre-oriented yarn is the same as that in Example 1, except that the relative viscosity of the polyamide 56 resin is 2.3.

[0137] The preparation method of the polyamide 56 stretch yarn is the same as that in Example 1.

[0138] Comparative Example 10

[0139] The method for preparing polyamide 56 pre-oriented yarn is the same as that in Example 1, except that the pressure of the component is controlled to be 10 MPa.

[0140] The preparation method of the polyamide 56 stretch yarn is the same as that in Example 1.

[0141] Comparative Example 11

[0142] The method for preparing polyamide 56 pre-oriented yarn is the same as that in Example 1, except that the overfeeding between the second yarn guide disk and the winding head is controlled to be 60 m / min.

[0143] The preparation method of the polyamide 56 stretch yarn is the same as that in Example 1.

[0144] Comparative Example 12

[0145] The preparation method of polyamide 6 pre-oriented yarn is the same as that of Example 1, except that the raw materials are different, and in step (1), the relative viscosity of the polyamide 6 resin is 2.50. The screw is heated in four zones, wherein the temperature of zone 1 is 230°C, the temperature of zone 2 is 240°C, the temperature of zone 3 is 245°C, and the temperature of zone 4 is 250°C.

[0146] In step (2), the spinning box temperature is 250°C.

[0147] The preparation method of the polyamide 6 stretch yarn is the same as that in Example 1.

[0148] Comparative Example 13

[0149] The preparation method of polyamide 66 pre-oriented yarn is the same as that of Example 1, except that the raw materials are different and in step (1), the relative viscosity of the polyamide 66 resin is 2.45. The screw is heated in four zones, wherein the temperature of zone 1 is 270°C, the temperature of zone 2 is 280°C, the temperature of zone 3 is 290°C, and the temperature of zone 4 is 290°C.

[0150] In step (2), the spinning box temperature is 290°C.

[0151] The preparation method of the polyamide 66 stretch yarn is the same as that in Example 1.

[0152] The fiber parameters of polyamide 56 pre-oriented yarn and stretched yarn prepared in Examples 1-11 and Comparative Examples 1-13 are shown in Table 1.

[0153] Table 1 Physical properties of polyamide 56 fiber

[0154]

[0155]

[0156] As can be seen from Table 1, the present invention effectively improves the molecular chain directivity during fiber spinning, high-speed orientation-induced crystallization by optimizing the spinning process, such as increasing the spinning speed, selecting a suitable spinneret hole diameter and increasing the spinneret stretching ratio, and further optimizes the spinning conditions: adjusting the cooling wind speed, wind temperature, wind humidity, side blowing height, oiling height, oiling concentration, etc., to improve the crystallization performance of polyamide 56 during spinning, and the mechanical properties of the prepared polyamide 56 pre-oriented yarn are greatly improved. Moreover, the prepared elasticized yarn has a low broken rate, and the polyamide 56 elasticized yarn has good bulkiness, good curling effect, and good dyeing performance.

Claims

1. A method for preparing high-strength and high-elongation polyamide 56 pre-oriented yarn, characterized in that: The preparation method comprises the following steps: (1) Providing a polyamide 56 melt; (2) The polyamide 56 melt is transported to the spinning manifold through a melt pipe, accurately metered by a metering pump, injected into the spinning assembly, and extruded from the spinneret hole to form primary yarn; The spun yarn is cooled, oiled, and wound to form, the spinning speed is controlled to be 4400-5500 m / min, and the spinneret stretching ratio is controlled to be 160-500 to obtain the polyamide 56 pre-oriented yarn; Wherein, during the spinning process of the polyamide 56 pre-oriented yarn, the cooling wind speed is controlled to be 0.38-0.50 m / s, the wind temperature is 16-23° C., and the wind humidity is 70-95%; the side blowing height is controlled to be ≥140 cm; the oiling height is controlled to be 90-150 cm, and the oiling concentration is controlled to be 0.4-0.5wt%; The high-strength and high-elongation polyamide 56 pre-oriented yarn has a breaking strength of 3.6-5.0 cN / dtex, a breaking strength variation coefficient of ≤2%, a breaking elongation of ≤90%, a breaking elongation variation coefficient of ≤3.0%, a yarn unevenness of ≤1.5%, and an orientation factor of ≥0.6; During the spinning process of the polyamide 56 pre-oriented yarn, the number of broken single yarns of the high-strength and high-elongation polyamide 56 pre-oriented yarn is ≤2 / 24h, the number of hairy yarns is ≤2 / 12kg package, and the manufacturing rate is ≥98%.

2. The preparation method according to claim 1, characterized in that: During the spinning process of the polyamide 56 pre-oriented yarn, the spinning speed is controlled to be 4500-5000 m / min; and / or, The number of broken single filaments of the high-strength and high-elongation polyamide 56 pre-oriented filaments is ≤1 / 24h; and / or, The number of the high-strength and high-elongation polyamide 56 pre-oriented yarns is ≤1 yarn / 12kg package; and / or, The production rate of the high-strength and high-elongation polyamide 56 pre-oriented yarn is ≥99%; and / or, The breaking strength of the high-strength and high-elongation polyamide 56 pre-oriented yarn is 3.7 to 4.8 cN / dtex; and / or, The coefficient of variation of the breaking strength of the high-strength and high-elongation polyamide 56 pre-oriented yarn is ≤1.5%; and / or, The elongation at break of the high-strength and high-elongation polyamide 56 pre-oriented yarn is ≤85%; and / or, The coefficient of variation of elongation at break of the high-strength and high-elongation polyamide 56 pre-oriented yarn is ≤2.0%; and / or, The unevenness of the strands of the high-strength and high-elongation polyamide 56 pre-oriented yarn is ≤1.3%; and / or, The orientation factor of the high-strength and high-elongation polyamide 56 pre-oriented yarn is ≥0.

7.

3. The preparation method according to claim 1, characterized in that: During the spinning process of the polyamide 56 pre-oriented filaments, the spinneret stretch ratio is controlled to be 180 to 230; and / or, During the spinning process of the polyamide 56 pre-oriented yarn, the spinning speed is controlled to be 4500-4700 m / min; and / or, The number of broken single filaments of the high-strength and high-elongation polyamide 56 pre-oriented filament is 0 / 24h; and / or, The number of the high-strength and high-elongation polyamide 56 pre-oriented yarns is 0 per 12kg package; and / or, The production rate of the high-strength and high-elongation polyamide 56 pre-oriented yarn is ≥99.5%; and / or, The breaking strength of the high-strength and high-elongation polyamide 56 pre-oriented yarn is 3.9-4.6 cN / dtex; and / or, The coefficient of variation of the breaking strength of the high-strength and high-elongation polyamide 56 pre-oriented yarn is ≤1.0%; and / or, The elongation at break of the high-strength and high-elongation polyamide 56 pre-oriented yarn is ≤80%; and / or, The coefficient of variation of elongation at break of the high-strength and high-elongation polyamide 56 pre-oriented yarn is ≤1.5%; and / or, The unevenness of the strands of the high-strength and high-elongation polyamide 56 pre-oriented yarn is ≤1.0%; and / or, The orientation factor of the high-strength and high-elongation polyamide 56 pre-oriented yarn is ≥0.

8.

4. The preparation method according to claim 1, characterized in that: During the spinning process of the polyamide 56 pre-oriented yarn, the cooling wind speed is controlled to be 0.40-0.48 / s; the wind temperature is controlled to be 17-22° C.; and the wind humidity is controlled to be 75-90%.

5. The preparation method according to claim 1, characterized in that: During the spinning process of the polyamide 56 pre-oriented yarn, the cooling wind speed is controlled to be 0.42-0.46 / s; and / or, The wind temperature is 18-21℃; and / or, Wind humidity is 80-85%; and / or, Control the side blowing height to ≥150cm; and / or, Control the oiling height to 100-140cm.

6. The preparation method according to claim 1, characterized in that: During the spinning process of the polyamide 56 pre-oriented yarn, the oiling height is controlled to be 110 to 130 cm; and / or, Control the side blowing height to 160cm~200cm.

7. The preparation method according to claim 1, characterized in that: The polyamide 56 melt is obtained by heating polyamide 56 resin chips to a molten state, or the polyamide 56 melt obtained by a continuous polymerization device is directly spun; The relative viscosity of the polyamide 56 resin or melt is 2.40-2.

85.

8. The preparation method according to claim 7, characterized in that: The polyamide 56 resin slice is heated to a molten state by a screw to obtain a polyamide 56 melt, and the screw is heated in four zones, wherein the temperature of zone 1 is 250-280°C; the temperature of zone 2 is 260-285°C; the temperature of zone 3 is 270-290°C; the temperature of zone 4 is 275-295°C; and / or, The relative viscosity of the polyamide 56 resin or melt is 2.43 to 2.

82.

9. The preparation method according to claim 8, characterized in that: The relative viscosity of the polyamide 56 resin or melt is 2.45 to 2.78; and / or, The temperature of the first zone is 260-275°C; and / or, The temperature of the second zone is 265-280°C; and / or, The temperature of the three zones is 275-285° C.; and / or, The temperature of the four zones is 280-290°C.

10. The preparation method according to claim 8, characterized in that: The temperature of the first zone is 270° C.; and / or, The temperature of the second zone is 280°C; and / or, The temperature of the three zones is 285°C; and / or, The temperature of the fourth zone is 280°C.

11. The preparation method according to claim 1, characterized in that: The spinning box temperature is 275-285°C; and / or, The spinning assembly pressure is 15-18 MPa.

12. The preparation method according to claim 1, characterized in that: The spinning box temperature is 280-283°C; and / or, The spinning assembly pressure is 13-20 MPa.

13. The preparation method according to claim 1, characterized in that: The winding is carried out between two guide wire discs, and the primary yarn first passes through the first guide wire disc, then to the second guide wire disc, and finally is wound into shape; wherein, the underfeeding between the first guide wire disc and the second guide wire disc is ≤20m / min; the overfeeding between the second guide wire disc and the winding head is ≤50m / min.

14. The preparation method according to claim 13, characterized in that: The underfeeding rate of the first godet and the second godet is ≤15m / min; and / or, The overfeed between the second wire guide disk and the winding head is ≤30m / min.

15. The preparation method according to claim 13, characterized in that: The underfeeding rate of the first godet and the second godet is 5 to 20 m / min; and / or, The overfeed between the second wire guide disc and the winding head is 10 to 50 m / min.

16. The preparation method according to claim 13, characterized in that: The underfeeding rate of the first godet and the second godet is 10 m / min; and / or, The overfeed between the second wire guide disk and the winding head is 20m / min.

17. A high-strength and high-elongation polyamide 56 pre-oriented yarn, prepared by the preparation method according to any one of claims 1 to 16.

18. A polyamide 56 stretch yarn prepared from the high-strength and high-elongation polyamide 56 pre-oriented yarn according to claim 17, characterized in that: The curling shrinkage rate of the polyamide 56 elastic yarn is ≥35%.

19. The polyamide 56 stretch yarn according to claim 18, characterized in that: The curl stability of the polyamide 56 stretch yarn is ≥38%; and / or, The polyamide 56 stretch yarn has a breakage rate of ≤5%; and / or, The dyeing double A rate of the polyamide 56 stretch yarn is ≥96%.

20. The polyamide 56 stretch yarn according to claim 18, characterized in that: The curl shrinkage rate of the polyamide 56 stretch yarn is ≥40%; and / or, The curl stability of the polyamide 56 stretch yarn is ≥42%; and / or, The polyamide 56 stretch yarn has a breakage rate of ≤3%; and / or, The dyeing double A rate of the polyamide 56 stretch yarn is ≥97%.

21. The polyamide 56 stretch yarn according to claim 18, characterized in that: The curl shrinkage rate of the polyamide 56 stretch yarn is ≥45%; and / or, The curl stability of the polyamide 56 stretch yarn is ≥46%; and / or, The polyamide 56 stretch yarn has a breakage rate of ≤2%; and / or, The dyeing double A rate of the polyamide 56 stretch yarn is ≥98%.

22. The method for preparing the polyamide 56 stretch yarn according to any one of claims 18 to 21, characterized in that: The high-strength and high-strength polyamide 56 pre-oriented yarn of claim 17 is passed through a yarn guide and a yarn cutter, and then passed through the first roller; then sequentially stretched in a hot box, cooled by a cooling plate, shaped at room temperature, false twisted, and passed through the second roller; then processed by a network nozzle, passed through the third roller, oiled, and wound to obtain a polyamide 56 stretch yarn; Among them, the temperature of the hot stretching is 140-200°C, and the multiple is 1.25-1.40; the false twist friction plate is a C-type disk, a D-type disk or a PU-type disk; the D / Y of the false twist is 1.6-2.2; the T2 processing tension of the false twist is controlled to be 0.8-1.1 times the T1 processing tension; the winding speed is 500-800m / min.

23. Use of the high-strength and high-elongation polyamide 56 pre-oriented yarn according to claim 17 or the polyamide 56 elastic yarn according to any one of claims 18 to 21 in the fields of knitted and woven fabrics, carpet yarns, and blended yarns.

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