High-shrinkage easy-to-dye mixed fiber and preparation method thereof

Abstract

The invention discloses a high-shrinkage easy-to-dye mixed fiber and a preparation method thereof.The method comprises the steps that polyester melt is extruded and cooled to prepare nascent fibers, part of the nascent fibers are oiled and drafted to prepare FDY, and the other nascent fibers are oiled to prepare POY; the FDY filaments and the POY filaments are subjected to network fiber blending and winding to obtain blended filaments; the drafting is five-roller drafting, the temperature of a hot roller HR1, the temperature of a hot roller HR2 and the temperature of a hot roller HR3 are 82-87 DEG C, the temperature of a hot roller HR4 and the temperature of a hot roller HR5 are 95-105 DEG C, and the draw ratios of the hot roller HR1, the hot roller HR2, the hot roller HR3, the hot roller HR4 and the hot roller HR5 are 1.01-1.2, 1.10-1.5, 2.5-3.0 and 1 in sequence; the draw ratio of a spinning nozzle during extrusion is 165-180%; the boiling water shrinkage rate of the combined filament yarn is 60 + / -5%, and the differential shrinkage rate is 43-50%. The fabric prepared from the mixed fibers has excellent wool feeling, softness and drapability, and is outstanding in dyeing performance.

Description

Technical Field

[0001] The present application relates to the field of polyester yarns, and in particular to a high-shrinkage and easily dyeable mixed fiber and a preparation method thereof. Background Art

[0002] The preparation of traditional ITY blended fibers requires multi-step composite processing, but in recent years, a one-step process for preparing FDY / POY blended fibers has been developed by modifying FDY equipment. For example, the patent application with publication number CN118880515A discloses a direct spinning three-in-one production equipment and its application. This process directly integrates pre-oriented yarn (POY) and fully drawn yarn (FDY) into existing FDY equipment for extrusion blending, effectively simplifying the production process and improving efficiency. The differential shrinkage characteristics of POY and FDY can form a micro-curled structure similar to silk in subsequent heat treatment, giving the blended yarn a soft feel, high resilience and fluffy drape.

[0003] The boiling water shrinkage of high-shrinkage ITY blended fibers generally exceeds 20%, and some can reach 60-70%. Its high shrinkage is mainly due to the low orientation and low crystallinity structure of the POY component, which causes the blended fabric to shrink significantly during wet heat treatment; while FDY has a lower shrinkage due to its high orientation and high crystallinity. On the one hand, this structural characteristic of POY leads to a decrease in the overall crystallinity of the blended fibers and a loose arrangement of molecular chains, thereby significantly improving dye permeability. On the other hand, increasing the shrinkage difference between POY and FDY (i.e., differential shrinkage) allows the low-shrinkage FDY to form a richer curling structure distributed on the outer layer of the high-shrinkage POY after heat treatment, enhancing the fluffy feel of the fabric.

[0004] However, the high differential shrinkage rate leads to a high proportion of FDY with high crystallinity in the outer layer of the mixed fiber, making the fabric feel hard; at the same time, FDY is difficult to fully fit the shrinkage deformation of POY, and the stress between fibers is concentrated, resulting in reduced softness. In addition, the high differential shrinkage leads to poor structural stability of the fabric and deterioration of drape. Summary of the invention

[0005] In order to solve the problem that it is difficult to achieve both hairy feel and softness and drape in current differentially-shrinked blended fiber fabrics, the present application provides a high-shrinkage and easy-to-dye blended fiber and a preparation method thereof, which effectively regulates the differential shrinkage rate of the blended fibers, ensures the balance between the hairy feel and softness and drape of the fabric, and effectively improves the dyeing rate.

[0006] In a first aspect, the present application provides a method for preparing a high-shrinkage and easily dyeable mixed fiber: Polyester melt is extruded and cooled to obtain spun fibers, part of the spun fibers are oiled and drawn to obtain FDY yarns, and the remaining spun fibers are oiled to obtain POY yarns; the FDY yarns and POY yarns are mixed and wound to obtain mixed fiber yarns; the drawing is a five-roller drawing, wherein the temperatures of hot rollers HR1, HR2, and HR3 are 82-87°C, the temperatures of HR4 and HR5 are 95-105°C, and the stretching ratios of HR1, HR2, HR3, HR4, and HR5 are 1.01-1.2, 1.10-1.5, 2.5-3.0, and 1, respectively; the spinneret stretching ratio during extrusion is 165-180; the boiling water shrinkage of the mixed fiber yarn is 60±5%, and the abnormal shrinkage is 43-50%.

[0007] The boiling water shrinkage of the blended yarn is controlled at 60±5%, and the differential shrinkage is within the range of 43-50%. The blended yarn has a relatively balanced hairy feel, softness and drape. If the boiling water shrinkage of the blended yarn is too low, the hairy feel decreases, and if the shrinkage is too high, the hand feel is hard and the drape is poor. Since the boiling water shrinkage of the blended yarn depends on the boiling water shrinkage of the POY yarn, the present application controls the spinneret stretching ratio at 165-180 to ensure that the POY yarn has a higher degree of orientation and boiling water shrinkage. It should be noted that, under the condition of consistent melt, the spinneret stretching ratio depends on the winding speed.

[0008] Furthermore, by adjusting the hot roller drawing process, the shrinkage rate of the FDY yarn can be effectively improved to obtain a suitable differential shrinkage rate. Specifically, the present application increases the stretching ratio between hot rollers, which helps to promote the improvement of fiber orientation and increase the shrinkage rate. At the same time, the setting temperature (HR4, HR5 temperature) is appropriately reduced to inhibit the deorientation and crystallization caused by high temperature, which helps to improve the dyeability while increasing the shrinkage rate. The stretching temperature (HR1, HR2, HR3 temperature) needs to be higher than the glass transition temperature of polyester (greater than 67-81°C) to ensure the mobility of the molecular chain segments and achieve high orientation of the molecules.

[0009] The spinneret stretch ratio should be moderate. Although an increased spinneret stretch ratio helps to improve the fiber orientation and induce the crystallization of polyester molecules, thereby increasing the breaking strength of the mixed fiber, an excessively high stretch ratio will also cause the crystal particle size to increase rapidly, resulting in lattice defects, and the strength will decrease, which can easily lead to single filament breakage and the production of hairy fibers.

[0010] It should be noted that the above-mentioned FDY / POY blended fibers are prepared by a one-step method, that is, the spun fibers extruded from half of the spinning positions of the spinneret are oiled and bundled and then enter the hot roller box for drawing to produce highly oriented FDY drawn fibers; the spun fibers extruded from the other half of the spinning positions are oiled and bundled to produce low-oriented and low-crystallized POY pre-oriented fibers.

[0011] In any of the above technical solutions, the cooling adopts a gradient ring blowing cooling process, including: First cooling zone: 50-400mm from spinneret, wind speed 1.0-1.5m / s; Second stage cooling zone: 400-600mm from spinneret, wind speed 0.5-1.0m / s; The third cooling zone is 600-1000mm away from the spinneret, with a wind speed of 0.2-0.5m / s.

[0012] In any of the above technical solutions, the cooling air temperature is 20±1°C and the humidity is 80-90%.

[0013] In conventional processes, in order to improve the fiber dye uptake rate, it is usually necessary to reduce its crystallinity and orientation to increase the pores for dye molecules to penetrate and migrate. However, in the present application, the reduction in orientation will cause the deterioration of the wooly feel of the fabric, and the excessive reduction in crystallinity is not conducive to improving the breaking strength and reducing the fuzz. The present application sets a gradient cooling process, especially the initial rapid cooling stage (a cold zone), which can form a temperature gradient between the interior and the surface of the primary fiber. Under high spinneret stretching ratio conditions, the fiber surface condenses quickly and the orientation is higher than the interior, causing crystal defects and stress concentration on the surface, thereby forming microcracks. These crystal defects and microcracks help the dye molecules penetrate into the fiber, improving the dye uptake rate and dyeing uniformity.

[0014] It should be noted that the speed of the first stage of cooling should be greater than or equal to 1.0m / s to form appropriate defects and microcracks. In addition, a cold zone should be located 50 to 400mm below the spinneret. If the distance from the spinneret is too short (less than 50mm), it is easy to cause melt fracture; if it is too long, it is not conducive to the formation of the above defects and cracks. The length of a cold zone should not be too long. The temperature of the fiber molecular chain segment activity should be appropriately maintained so that the fiber can obtain sufficient orientation (shrinkage) and crystallinity during the nozzle stretching process to ensure the shrinkage and breaking strength of the fiber. The subsequent second and third stages control the fiber temperature to gradually cool until it reaches the solidification point. Among them, the second stage cooling ensures that the melt temperature is greater than the glass transition temperature, which is conducive to obtaining fibers with high orientation and high shrinkage.

[0015] In order to realize the above-mentioned gradient ring-blowing cooling process, the original annular static pressure chamber can be divided into three independent annular areas along the fiber axis (vertical direction), corresponding to the first, second and third cold zones respectively. Each annular static pressure chamber is equipped with an independent air valve (such as a butterfly valve or a Venturi valve), and the air intake of each section is controlled by adjusting the valve opening to achieve wind speed classification. The main air duct is divided into three independent channels, which are connected to three annular static pressure chambers respectively. An independent high-efficiency filter (such as H13 grade) is installed at the entrance of each channel to ensure the consistent cleanliness of the cooling air and avoid fiber contamination; each static pressure chamber is equipped with a wind pressure sensor interface to monitor and feedback the pressure data to the control system in real time, and dynamically adjust the air valve opening. The cooling air is centrally processed by the central air-conditioning system to ensure that the air temperature of the three static pressure chambers is constant at 20±1℃ and the humidity is 80~90%, avoiding fluctuations in temperature and humidity in different zones.

[0016] In any of the above technical solutions, the height of the oil rack for oiling is 350-450 mm.

[0017] The oil rack height in this application refers to the distance from the spinneret to the oil nozzle. Using a low oil rack height can reduce the fiber bundling distance, reduce the bundle tension, and inhibit the bundle jitter under high drawing ratio and high wind speed, thereby improving the spinning stability and reducing hairy fibers.

[0018] In any of the above technical solutions, the winding speed is 3000-3200 m / min, and the spinning temperature is 286-290°C.

[0019] In any of the above technical solutions, the FDY yarn is oiled with a diluent oil having an oil content of 25 to 35 wt%, and the POY yarn is oiled with a diluent oil having an oil content of 8 to 12 wt%.

[0020] The diluent oil is a conventional spinning oil in the art, which is prepared by adding the oil into water containing an emulsifier and stirring the mixture evenly.

[0021] Exemplarily, the diluent oil is prepared by dispersing and mixing 30 wt % of an oil agent (TK-1009), an emulsifier (2 wt %) and water.

[0022] The diluent oil used for oiling contains 3-5wt% of benzyl alcohol.

[0023] Exemplarily, the diluent oil is prepared by dispersing and mixing 30 wt % of an oil agent (TK-1009), 4 wt % of benzyl alcohol, an emulsifier (2 wt %) and water.

[0024] During the hot roller drawing process, the benzyl alcohol attached to the filament bundle has good penetration and swelling ability for the primary fibers after the gradient cooling, which helps to improve the activity of the molecular chain segments, improve the fiber orientation, improve the FDY shrinkage and dyeing performance, and reduce the differential shrinkage, thereby ensuring the softness and drape of the mixed fiber fabric.

[0025] In any of the above technical solutions, the yarn guide for preparing the mixed yarn is a rotating yarn guide wheel.

[0026] In the preparation process of mixed fibers, the function of the wire guide and wire hook is to guide the silk thread to move along a specific path to avoid entanglement or deviation. The ceramic parts are the parts that are in direct contact with the silk thread. The ceramic parts can improve durability, reduce maintenance times, maintain the quality of the silk thread, and avoid pollution or static electricity problems that may be caused by metal parts. However, for mixed fibers, especially POY fibers with low crystallinity, the friction with the ceramic parts will produce an instantaneous high temperature higher than the setting temperature, causing the local crystallization of the fiber to set. These crystallized parts are difficult to be penetrated by dye molecules, resulting in the whitening of the fabric after dyeing, reducing the uniformity of dyeing.

[0027] To solve the above problems, the present application sets the porcelain parts of conventional yarn guides and yarn guide hooks as a rotating structure, specifically fixing the porcelain parts on a rotating shaft, and the rotating shaft is rotatably connected to the frame. During spinning, the rotation of the porcelain parts can effectively reduce the friction resistance between the yarn bundle and the porcelain parts.

[0028] In any of the above technical solutions, the network mixed fiber includes a pre-network and a main network, the pre-network pressure is 0.1-0.3 MPa, and the main network pressure is 0.3-0.6 MPa.

[0029] In a second aspect, the present application provides a high-shrinkage, easily dyeable blended fiber, which is prepared by any of the above-mentioned preparation methods.

[0030] In summary, this application has the following beneficial effects: The present application provides a high-shrinkage, easy-to-dye blended fiber and a one-step preparation process thereof, and coordinates the fiber structure through gradient ring-blowing cooling and five-roller drafting. A three-stage ring-blowing cooling is adopted to form a temperature gradient below the spinneret, so that crystal defects and microcracks are produced on the fiber surface, thereby improving dyeing permeability; the orientation difference between POY and FDY is precisely controlled by five-roller drafting, so that the boiling water shrinkage of the blended fiber reaches 60±5% and the differential shrinkage rate is 43-50%. In addition, by introducing benzyl alcohol into the spinning oil, the activity of the molecular chain is enhanced and the hair is suppressed. The resulting blended fiber has a high dyeing rate, a high fluffy feel and a soft drape, which solves the problem of hardened feel of traditional high-shrinkage blended fibers due to the imbalance of differential shrinkage. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the production process of the high-shrinkage and easy-dyeing mixed fiber of the present application.

[0032] Figure 2 is a schematic diagram of a conventional wire guide.

[0033] Figure 3 It is a schematic diagram of the rotating wire guide wheel of the present application. DETAILED DESCRIPTION

[0034] The polyester melt used in the following examples and comparative examples has an intrinsic viscosity of 0.640 dL / g, a terminal carboxyl value of 44 mol / t, and a melting point of 254°C.

[0035] Example 1, a high shrinkage and easy-to-dye fiber is prepared as follows: The polyester melt is extruded from the spinneret (spinning box temperature 286-290℃, spinneret stretch ratio 165) and subjected to gradient ring blowing cooling, and then cooled and formed in the first, second and third cooling zones to obtain nascent fibers. Among them, the first cooling zone is 50-400mm away from the spinneret, with a wind speed of 1.4m / s; the second cooling zone is 400-600mm away from the spinneret, with a wind speed of 0.8m / s; the third cooling zone is 600-1000mm away from the spinneret, with a wind speed of 0.3m / s; the ring wind temperature is 20℃ and the humidity is 85%. Half of the nascent fibers are oiled and bundled with diluent oil (TK-1009 oil 28wt%, emulsifier 2wt%, water as the balance, oil temperature 40℃), and the oil rack height is 400mm. After oiling, the tow enters the five-roller hot roller box for drawing and shaping through the wire guide GR0. Among them, the drawing ratio between HR1 (950m / min) and HR2 (1000m / min) is 1.05, the drawing ratio between HR2 and HR3 (1120m / min) is 1.12, the drawing ratio between HR3 and HR4 (3115m / min) is 2.78, and there is no drawing between HR4 and HR5 (3115m / min); the temperature of the stretching rollers HR1~HR3 is 85~87℃, and the temperature of the shaping rollers HR4~HR5 is 100±2℃, and FDY yarn is made. The other half of the primary fiber is oiled and bundled with diluent oil (TK-1009 oil agent 9wt%, emulsifier 1wt%, water as the balance, oil temperature 40℃), and the oil rack height is 400mm to make POY yarn.

[0036] FDY yarn passes through the GR1 godet and POY yarn into the pre-networking device for network mixing (air pressure 0.2MPa), and then passes through the GR2 godet to enter the main network device (air pressure 0.4MPa) for network mixing. Then it passes through the godet and enters the winder (3100m / min) to obtain 130 dtex / 84F high shrinkage easy-to-dye fiber. The winder's godet hook and godet are both rotating godet wheels.

[0037] Embodiment 2, a kind of high shrinkage easy dyeing fiber, is prepared by the following method: The polyester melt is extruded from the spinneret (spinning box temperature 286-290℃, spinneret stretch ratio 168) and subjected to gradient ring blowing cooling, and then cooled and formed in the first, second and third cooling zones to obtain nascent fibers. Among them, the first cooling zone is 50-400mm away from the spinneret, with a wind speed of 1.2m / s; the second cooling zone is 400-600mm away from the spinneret, with a wind speed of 1.0m / s; the third cooling zone is 600-1000mm away from the spinneret, with a wind speed of 0.3m / s; the ring wind temperature is 20℃ and the humidity is 80%. Half of the nascent fibers are oiled and bundled with diluent oil (TK-1009 oil 25wt%, emulsifier 2wt%, water as the balance, oil temperature 40℃), and the oil rack height is 400mm. After oiling, the tow enters the five-roll hot roller box for drawing and shaping through the wire guide plate GR0. Among them, the drawing ratio between HR1 (950m / min) and HR2 (1100m / min) is 1.16, the drawing ratio between HR2 and HR3 (1375m / min) is 1.25, the drawing ratio between HR3 and HR4 (3115m / min) is 2.65, and there is no drawing between HR4 and HR5 (3115m / min); the temperature of the drawing rollers HR1~HR3 is 85~87℃, and the temperature of the shaping rollers HR4~HR5 is 102±2℃, and FDY yarn is made. The other half of the primary fiber is oiled and bundled with diluent oil (TK-1009 oil 12wt%, emulsifier 1wt%, water as the balance, oil temperature 40℃), and the oil rack height is 400mm to make POY yarn. The winding machine wire guide hook and wire guide are both rotating wire guide wheels.

[0038] The FDY yarn passes through the godet GR1 and the POY yarn into the pre-networking device for network mixing (air pressure 0.3MPa), and then passes through the godet GR2 into the main network device (air pressure 0.5MPa) for network mixing. Then, it passes through the godet GR3 and enters the winding machine (3110m / min) to obtain 130 dtex / 84F high shrinkage and easy-to-dye fiber.

[0039] Embodiment 3, a kind of high shrinkage easy dyeing fiber, is prepared by the following method: The polyester melt is extruded from the spinneret (spinning box temperature 286-290℃, spinneret stretch ratio 176) and subjected to gradient ring blowing cooling, and then cooled and formed in the first, second and third cooling zones to obtain nascent fibers. Among them, the first cooling zone is 50-400mm away from the spinneret, with a wind speed of 1.1m / s; the second cooling zone is 400-600mm away from the spinneret, with a wind speed of 0.5m / s; the third cooling zone is 600-1000mm away from the spinneret, with a wind speed of 0.4m / s; the ring wind temperature is 19.5℃ and the humidity is 85%. Half of the nascent fibers are oiled and bundled with diluent oil (TK-1009 oil 33wt%, emulsifier 2wt%, water as the balance, oil temperature 40℃), and the oil rack height is 400mm. After oiling, the tow enters the five-roll hot roller box for drawing and shaping through the wire guide plate GR0 (rotation speed 940m / min), among which the drawing ratio between HR1 (950m / min) and HR2 (1000m / min) is 1.05, the drawing ratio between HR2 and HR3 (1120m / min) is 1.12, the drawing ratio between HR3 and HR4 (3115m / min) is 2.90, and there is no drawing between HR4 and HR5 (3115m / min); the temperature of the drawing rollers HR1~HR3 is 85~87℃, and the temperature of the shaping rollers HR4~HR5 is 98±2℃, and FDY yarn is made. The other half of the nascent fiber is oiled and bundled with diluent oil (TK-1009 oil 8wt%, emulsifier 1wt%, water as the balance, oil temperature 40℃), and the oil rack height is 400mm to make POY yarn. The wire guide hook and wire guide of the winding machine are both rotating wire guide wheels.

[0040] The FDY yarn passes through the godet GR1 and the POY yarn into the pre-networking device for network mixing (air pressure 0.2MPa), and then passes through the godet GR2 into the main network device (air pressure 0.4MPa) for network mixing. Then, it passes through the godet GR3 and enters the winding machine (3110m / min) to obtain 130 dtex / 84F high shrinkage easy-to-dye fiber.

[0041] Example 4 is a high shrinkage and easily dyeable fiber. The difference from Example 1 is that the diluent oil used for the FDY yarn and the POY yarn contains 3.3 wt % of benzyl alcohol (the amount of water in the diluent oil is reduced accordingly).

[0042] Example 5, a high shrinkage and easily dyeable fiber, is different from Example 1 in that the diluent oil used for the FDY yarn and the POY yarn contains 4.5 wt % of benzyl alcohol (the amount of water in the diluent oil is reduced accordingly).

[0043] Example 6, a high-shrinkage, easily dyeable fiber, differs from Example 1 in that gradient ring-blowing cooling includes: a first-stage cooling zone: 50 to 400 mm from the spinneret, with a wind speed of 0.8 m / s; a second-stage cooling zone: 400 to 600 mm from the spinneret, with a wind speed of 0.8 m / s; a third-stage cooling zone: 600 to 1000 mm from the spinneret, with a wind speed of 0.3 m / s.

[0044] Example 7, a high-shrinkage, easily dyeable fiber, differs from Example 1 in that gradient ring-blowing cooling includes: a first-stage cooling zone: 50 to 600 mm from the spinneret, with a wind speed of 1.4 m / s; a second-stage cooling zone: 400 to 600 mm from the spinneret, with a wind speed of 1.4 m / s; a third-stage cooling zone: 600 to 1000 mm from the spinneret, with a wind speed of 0.3 m / s.

[0045] Example 8, a high-shrinkage, easily dyeable fiber, differs from Example 1 in that gradient ring-blowing cooling includes: a first-stage cooling zone: 50 to 400 mm from the spinneret, with a wind speed of 1.4 m / s; a second-stage cooling zone: 400 to 600 mm from the spinneret, with a wind speed of 0.8 m / s; a third-stage cooling zone: 600 to 1000 mm from the spinneret, with a wind speed of 0.8 m / s.

[0046] Example 9, a high shrinkage and easily dyeable fiber, differs from Example 1 in that the gradient ring blowing cooling process is not adopted, and the wind speed in the cold zone 50 to 1000 mm away from the spinneret is 0.8 m / s.

[0047] Example 10 is a high shrinkage and easily dyeable fiber. The difference from Example 1 is that the winding machine adopts conventional non-rotating wire guide hooks and wire guides (the ceramic parts cannot rotate).

[0048] Comparative Example 1 is a high shrinkage and easily dyeable fiber, which differs from Example 1 in that the stretching ratio between HR1 (950 m / min) and HR2 (1000 m / min) is 1.05, the stretching ratio between HR2 and HR3 (1080 m / min) is 1.08, the stretching ratio between HR3 and HR4 (2600 m / min) is 2.4, and there is no stretching between HR4 and HR5.

[0049] Comparative Example 2 is a high shrinkage and easily dyeable fiber. The difference from Example 1 is that the temperature of the shaping rollers HR4-HR5 is 130±2°C.

[0050] Comparative Example 3 is a high shrinkage and easily dyeable fiber, which is different from Example 1 in that the spinneret stretching ratio during extrusion is 150%.

[0051] Comparative Example 4 is a high shrinkage and easily dyeable fiber, which is different from Example 1 in that the spinneret stretching ratio during extrusion is 190%.

[0052] The performance effects of the above embodiments and comparative examples are verified by experiments as follows.

[0053] 1. Refer to the provisions of FZ / T 54118-2019 "High-shrinkage Polyester Drawn Yarn / Polyester Pre-oriented Yarn Blended Yarn" to determine the breaking strength and boiling water shrinkage (S1) of high-shrinkage easy-dye blended yarn. The high-shrinkage easy-dye blended yarn was water-set at 80°C for 30 minutes, and then the dry heat shrinkage (S2) was measured at 190°C for 15 minutes. The different shrinkage of the blended fiber was then calculated by △S=S1-S2.

[0054] 2. Feel of blended fabrics: Weave blended yarns into plain fabrics (100mm×100mm), take samples and conduct the following tests: (1) Hairy feel: Boil in boiling water for 30 minutes and dry naturally. Five professionals will rate the feel of the fabric (1-5 points, 5 points being the hairiest).

[0055] (2) Softness: Refer to GB / T 18318.1-2009 "Determination of flexural properties of textile fabrics Part 1: Inclined plane method", use Handle-O-Meter (bending stiffness tester), sample size 25mm×150mm, test fabric bending stiffness (unit: mN·cm). The lower the value, the higher the softness.

[0056] (3) Drape: With reference to GB / T 23329-2009 “Determination of Drape of Textile Fabrics”, a circular specimen with a diameter of 240 mm is placed in a drape tester and the drape coefficient is calculated by the projection method (the smaller the value, the better the drape).

[0057] (4) Comprehensive evaluation of hand feel: blindly evaluated by 5 professionals, with hair feel, softness and drape each accounting for 1 / 3 of the weight, with a total score of 15 points. The higher the score, the better the overall hand feel.

[0058] 3. With reference to GB / T 6508-2015, the mixed fibers obtained in the embodiment and the comparative example were woven into socks and then dyed, and their dyeing uniformity was evaluated (grade 1-5, grade 5 being uniform); and the dye uptake of the socks was measured by a spectrophotometer.

[0059] Table 1. Performance test results

[0060] The dyeing rate (94-95%) of Example 4-5 (containing benzyl alcohol) is significantly improved compared with the dyeing rate (90-92%) of Example 1-3, and the dyeing uniformity reaches level 5.0, because benzyl alcohol can promote the improvement of the orientation degree of FDY yarn during the drawing process, inhibit the formation of crystalline areas, and promote the penetration of dye molecules.

[0061] In Example 6, the wind speed of the first cooling zone is set to the wind speed of the second cooling zone, resulting in the fiber not being cooled rapidly during the initial cooling process. Its dyeing rate (84.6%) is lower than that of Example 1 (91.3%) because the defects on the fiber surface are reduced and the dye penetration ability is reduced.

[0062] In Example 7, the wind speed of the second cooling zone is set to the wind speed of the first cooling zone, and in Example 8, the wind speed of the second cooling zone is set to the wind speed of the second cooling zone, which causes the high wind speed cooling zone to be too long, the fiber melt temperature to drop too quickly, resulting in insufficient stretching of the fiber, low orientation and crystallinity, and the dyeing rate dropped to 85-88%.

[0063] In Example 9, no gradient cooling was provided, and the fiber was fully stretched and oriented after extrusion, and its orientation degree and crystallinity were both high, but no defects were formed on the fiber surface, and the dyeing rate dropped to 83.2.

[0064] Example 10 uses a non-rotating yarn guide. Due to friction, local crystallization occurs, and whitening occurs during the dyeing process. The dyeing uniformity drops to level 3.5. Comparative Example 1: The draw ratio is insufficient (the drafting draw ratio is reduced), resulting in low FDY orientation, increased shrinkage, and hard fabric (softness 21.6mN·cm, drape coefficient 62%). Comparative Example 2: The setting temperature is too high, and the high temperature leads to increased FDY crystallinity, decreased dye molecule penetration effect, and dye uptake rate dropped to 70%, and poor softness (softness bending stiffness 23.5mN.cm, drape coefficient 66%). In comparative example 3, the nozzle stretching ratio is 150%, the POY orientation degree is insufficient, the boiling water shrinkage rate is only 55%, the abnormal shrinkage rate is too low, and the wooly feel is reduced.

[0065] In comparative example 4, the stretching ratio is 190%, the fiber lattice defects increase, the breaking strength is as low as 4.0 cN / dtex, and the hairy fiber rate is high.

[0066] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A method for preparing high-shrinkage and easy-dyeing mixed fibers, characterized in that: Polyester melt is extruded and cooled to obtain spun fibers, part of the spun fibers are oiled and drawn to obtain FDY yarns, and the remaining spun fibers are oiled to obtain POY yarns; the FDY yarns and POY yarns are mixed and wound to obtain mixed fiber yarns; the drawing is a five-roller drawing, wherein the temperatures of the hot rollers HR1, HR2, and HR3 are 82-87°C, the temperatures of HR4 and HR5 are 95-110°C, and the stretching ratios of HR1, HR2, HR3, HR4, and HR5 are 1.01-1.2, 1.10-1.5, 2.5-3.0, and 1, respectively; the spinneret stretching ratio during extrusion is 165-180; the boiling water shrinkage of the mixed fiber yarn is 60±5%, and the abnormal shrinkage is 43-50%.

2. The preparation method according to claim 1, characterized in that: The cooling adopts a gradient ring blowing cooling process, including: First cooling zone: 50-400mm from spinneret, wind speed 1.0-1.5m / s; Second stage cooling zone: 400-600mm from spinneret, wind speed 0.5-1.0m / s; The third cooling zone is 600-1000mm away from the spinneret, with a wind speed of 0.2-0.5m / s.

3. The preparation method according to claim 2, characterized in that: The cooling air temperature is 20.5±1°C and the humidity is 80-90%.

4. The preparation method according to claim 2, characterized in that: The oil rack for oiling is 350-450 mm in height.

5. The preparation method according to claim 1, characterized in that: The winding speed is 3000-3200 m / min, and the spinning temperature is 286-290°C.

6. The preparation method according to claim 1, characterized in that: The content of oiling agent in the diluent oil used for oiling the FDY yarn is 25-35wt%, and the content of oiling agent in the diluent oil used for oiling the POY yarn is 8-12wt%.

7. The preparation method according to claim 1, characterized in that: The diluent oil used for oiling contains 3-5wt% of benzyl alcohol.

8. The preparation method according to claim 1, characterized in that: The yarn guide for preparing the mixed yarn is a rotating yarn guide wheel.

9. The preparation method according to claim 1, characterized in that: The network mixed fiber includes a pre-network and a main network, the pre-network pressure is 0.1-0.3 MPa, and the main network pressure is 0.3-0.6 MPa.

10. A high shrinkage and easy-to-dye blended fiber, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 9.

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