DTY (Draw Textured Yarn) ingot as well as preparation method, application and dyeing method thereof

Abstract

The invention provides a DTY (Draw Textured Yarn) silk spindle and a preparation method, application and dyeing method thereof, the preparation method comprises the following steps: preheating, stretching, false twisting, heat setting, cooling, oiling and winding raw material yarns in sequence to obtain the DTY silk spindle, and the false twisting temperature is 200-220 DEG C. The steps of false twisting processing and heat setting are introduced into the preparation method of the DTY silk spindle, and the false twisting processing and the heat setting have a synergistic effect, so that the heat shrinkage rate of the polyester yarn can be reduced, and the dyeing uniformity of the polyester yarn can be improved.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical fiber textiles, and particularly relates to a DTY spindle, a preparation method and application thereof, and a dyeing method. Background Art

[0002] Polyester (polyethylene terephthalate, PET) is one of the most produced chemical fibers. Due to its excellent strength, abrasion resistance, chemical stability, and easy care, it is widely used in clothing, home textiles, and industrial fields. FDY (Fully Drawn Yarn) is a high-strength, high-elongation polyester filament. Its production process includes melt spinning, primary stretching, secondary stretching, and winding molding. It has the characteristics of a compact fiber structure, high crystallinity, and a regular cross-section. FDY polyester yarn has a high degree of orientation and a crystalline structure. Its dry heat shrinkage rate (180°C x 15 min) is 10-14%, and its boiling water shrinkage rate (100°C x 30 min) is 6-7%. As a result, when FDY polyester yarn is dyed using traditional dyeing processes, its high shrinkage rate can cause shrinkage differences between the inner and outer layers of the yarn during dyeing. At the same time, due to the dense internal structure of the yarn, problems such as color spots and grain differences can occur on the yarn surface after dyeing.

[0003] Although the above problems can be overcome by twisting and setting pretreatment, there are disadvantages such as complex process, poor efficiency and high energy consumption. In addition, the yarn has low specific surface area after setting, poor dyeing permeability, and large difference in shrinkage rate between the inner, middle and outer layers of the yarn.

[0004] Therefore, it is necessary to provide a new processing method that can improve the dyeing uniformity of polyester yarn. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the object of the present invention is to provide a DTY silk spindle and its preparation method and application, and dyeing method.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] On the one hand, the present invention provides a method for preparing a DTY spindle, the preparation method comprising: preheating, stretching, false twisting, heat setting, cooling, oiling and winding the raw yarn in sequence to obtain the DTY spindle, wherein the false twisting temperature is 200-220°C, for example, 200°C, 202°C, 205°C, 208°C, 210°C, 212°C, 215°C, 218°C, 220°C, etc.

[0008] When preparing DTY spindles, the present invention introduces the steps of false twisting and heat setting, and the two synergistically enhance the effect, thereby reducing the thermal shrinkage of polyester yarn and improving the dyeing uniformity of polyester yarn. False twisting is to apply mechanical twisting stress to the raw yarn to form a temporary twist. By applying false twist to the polyester yarn, the yarn can be formed into a curled structure. This process can partially destroy the high orientation structure of the yarn and reduce the internal stress of the fiber; at the same time, combined with heat setting, the yarn can be further relaxed, residual stress can be eliminated, and the crystal structure can be stabilized, thereby reducing the thermal shrinkage of the polyester yarn; therefore, the DTY spindle obtained by the preparation method provided by the present invention can reduce the thermal shrinkage of the polyester yarn, reduce the inner and outer layer difference of the spindle or loose cone, and thus improve the dyeing uniformity of the loose cone.

[0009] The preparation method of the DTY spindle provided by the present invention is also a pre-dyeing treatment method for polyester yarn, which includes preheating, stretching, false twisting, heat setting, cooling, oiling and winding the raw yarn in sequence. The method provided by the present invention reduces the thermal shrinkage rate of the polyester yarn, reduces the difference between the inner and outer layers of the loose cone, and improves the uniformity of dyeing.

[0010] Compared with the conventional false twist processing temperature of 180-200°C for polyester yarn, the present invention specifically selects a false twist processing temperature of 200-220°C, preferably 210-220°C, which can fully relax the orientation structure of the polyester yarn.

[0011] The present invention specifically describes the preparation method: the preparation method of the DTY silk spindle of the present invention can be carried out on any equipment that can currently implement the above steps. The present invention does not impose any limitation on this, and only provides examples for explanation. For example, it can be carried out on a texturing machine, including:

[0012] S1. Feeding: Raw yarn enters the texturing machine through the yarn guide tube;

[0013] S2 preheating: preheating the raw yarn using a non-contact heating method;

[0014] S3 stretching: by controlling the speed difference between the first roller and the second roller to achieve the stretching of the raw yarn;

[0015] S4 false twist: using a false twister to twist the preheated FDY yarn - untwist;

[0016] S5. Heat setting: Heat setting (and relaxation) of the yarn after false twisting by non-contact heating;

[0017] S6. Cooling: After heat setting, it enters the cooling plate for cooling;

[0018] S7. Optionally, mesh processing is performed after cooling;

[0019] S8. Oiling and winding to obtain DTY filament ingot.

[0020] The preparation method of the present invention can be applied to any polyester yarn to prepare DTY spindles, and preferably the raw yarn is FDY raw yarn.

[0021] The preparation method provided by the present invention can be used for FDY raw yarn, and can greatly reduce the dry heat shrinkage and boiling water shrinkage of the FDY raw yarn. Therefore, during the subsequent dyeing process, there is a smaller shrinkage difference between the inner and outer layers of the bobbin yarn, which can greatly increase the dyeing uniformity.

[0022] At the same time, the FDY yarn treated by the pretreatment method provided by the present invention has a certain curl structure, which increases the specific surface area of the yarn, improves the permeability of the dye solution, and reduces the risk of dyeing layer difference.

[0023] Preferably, step S1 is loading the raw yarn, placing the raw yarn on a yarn rack, and guiding the yarn into the texturing machine through a yarn guide. During the loading process, the tension is controlled to ensure that the FDY raw yarn enters the first roller with a stable tension, thereby avoiding tension fluctuations that affect subsequent processing;

[0024] In the present invention, step S2 preheating is first performed to improve the molecular chain activity of the polyester yarn and prepare for subsequent false twist deformation; preferably, the preheating temperature is 200-220°C, preferably 210-220°C, and preferably the non-contact heating method includes non-contact heating using a non-contact hot plate or heat pipe.

[0025] In the present invention, the raw yarn is preferably FDY yarn. Since the molecular chains of FDY yarn are oriented and crystallized, the stretching ratio is preferably 1.0-1.05 times, such as 1.01 times, 1.02 times, 1.03 times, 1.04 times, 1.05 times, etc., and preferably 1.01-1.02 times. The stretching ratio specified in the present invention can avoid problems such as yarn breakage caused by excessive stretching.

[0026] In the present invention, the stretching in step S3 is achieved by controlling the speed difference between the first roller and the second roller, wherein the first roller is also the feeding roller (FR), which pulls the raw yarn at a low speed, and the second roller is the stretching roller (MR / DR) which rotates at a high speed, and stretching is achieved by controlling the speed ratio (DR:FR) of the two.

[0027] In the present invention, the false twisting in step S4 is a twisting-untwisting process, and the false twisting temperature is 200-220°C, for example, 200°C, 202°C, 205°C, 208°C, 210°C, 212°C, 215°C, 218°C, 220°C, etc.

[0028] Preferably, the false twisting time is 3-10s, for example, 3s, 4s, 5s, 6s, 7s, 8s, 9s, 10s, etc.

[0029] Preferably, in the false twist, the D / Y ratio is 1.6-2.5, such as 1.6, 1.7, 1.8, 2.0, 2.2, 2.4, 2.5, etc., and the K value is 1.05-1.3, such as 1.05, 1.08, 1.1, 1.12, 1.15, 1.18, 1.2, 1.22, 1.25, 1.28, 1.3, etc.

[0030] In the present invention, the D / Y ratio is the ratio of the friction disk linear speed to the yarn speed, which can affect the false twist tension and the hair / tight point control; and the K value is the ratio of the untwisting tension T2 to the twisting tension T1, which affects the stability of the process. By limiting the D / Y ratio and the K value, the present invention can form a curled structure of the yarn while destroying the high orientation structure of the polyester yarn as much as possible, thereby releasing the stress within the fiber.

[0031] In the present invention, the polyester yarn is deformed by introducing false twist to give it a three-dimensional curl structure. Preferably, the false twist is performed using a false twister. Preferably, the false twister includes a mechanical false twister, which includes a friction disk. Twist is applied by high-speed rotation to form a temporary spiral curl. Due to the relaxation of molecular chain stress at high temperature, the curl morphology is "memorized". Therefore, after leaving the false twister, the twist is decomposed, but the curl structure is permanently retained to achieve deformation.

[0032] In the present invention, the heat setting temperature in step S5 is preferably 180-190°C, for example, 180°C, 181°C, 182°C, 183°C, 184°C, 185°C, 186°C, 187°C, 188°C, 189°C, 190°C, etc., and the preferred time is 10-30s, for example, 10s, 12s, 15s, 18s, 20s, 22s, 25s, 28s, 30s, etc.

[0033] In the present invention, heat setting can eliminate internal stress, stabilize the crimp structure, and reduce subsequent shrinkage. By setting a higher heat setting temperature and extending the heat setting time, the present invention can fully ensure the release of residual stress in the polyester yarn. At the same time, high-temperature heat setting can enable the micro-crimp structure generated by false twisting to form a stable shape memory, thereby reducing the thermal shrinkage of the polyester yarn.

[0034] The present invention relaxes the yarn by controlling the overfeed ratio while heat setting. The overfeed ratio is preferably 1.01-1.02, for example, 1.01, 1.02, etc. The present invention relaxes the yarn or heat sets it in a low-tension state by overfeeding (OF 1-2%), which rearranges and fixes the molecular chains, eliminates internal stress, and improves dimensional stability. By controlling the relaxed overfeed ratio, the bulkiness and elasticity of the yarn can be adjusted.

[0035] In the present invention, the cooling in step S6 is performed immediately after the heat setting. Preferably, the cooling is performed using a cooling plate. Rapid cooling can solidify the curled shape and prevent the structure from rebounding.

[0036] In the present invention, step S7 is an optional step. The grid processing is to form network nodes through compressed air, which can improve the cohesion of monofilaments. The network degree is adjusted by air pressure and overfeed rate. The present invention does not make specific limitations. Any parameters that can meet the application requirements can be applied to the present invention. It is preferred to use a compressed air nozzle to blow the silk strips to make the monofilaments entangled with each other, which can increase the cohesion and reduce the hair during weaving. It can replace traditional twisting and improve production efficiency.

[0037] In the present invention, the oiling in step S8 is preferably performed by oiling in a contact manner using an oiler or a spraying manner using a nozzle.

[0038] Preferably, the oil content of the yarn after oiling is 2.2-2.8%, for example, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, etc.

[0039] In the present invention, by oiling the yarn, the smoothness, antistatic property and weaving performance of the yarn can be enhanced, and at the same time, friction can be reduced and equipment can be protected.

[0040] Preferably, the winding forming is that the yarn is wound through the traverse guide rod and the winding roller to obtain a DTY spindle, and the winding tension is adjusted by the overfeed rate. The present invention is not specifically limited, and it is sufficient to ensure the tightness of the winding forming and the unwinding performance. An example thereof can be OF3%.

[0041] The preparation method provided by the present invention is particularly suitable for FDY yarn, and the pretreatment method provided by the present invention has high process adaptability. A traditional texturing machine can be used to adapt to FDY processing only by adjusting process parameters. The pretreatment method provided by the present invention is efficient and has low energy consumption.

[0042] In a second aspect, the present invention provides a DTY ingot prepared by the method for preparing a DTY ingot according to the first aspect.

[0043] In a third aspect, the present invention provides an application of the method for preparing the DTY spindle described in the first aspect in reducing the thermal shrinkage of FDY polyester yarn and improving dyeing uniformity.

[0044] In a fourth aspect, the present invention provides a dyeing method, comprising: loosening the DTY yarn spindles described in the second aspect, dyeing, washing, fixing and finishing.

[0045] Preferably, the loose cone adopts a honeycomb loose cone, and the preferred winding density is 0.25-0.35g / cm 3 , for example 0.25g / cm 3 , 0.28g / cm 3 , 0.30g / cm 3 , 0.32g / cm 3 , 0.35g / cm 3 etc., under the above winding density, a micro-coiled structure can be formed.

[0046] The silk spindle obtained by the preparation method provided by the present invention is rewound to obtain a bobbin yarn, and the yarn with a curled structure in the bobbin yarn has a higher specific surface area, which can increase the penetration rate of the dye and improve the dyeing uniformity.

[0047] Preferably, when performing the dyeing, the dye liquor circulation flow rate used is 25-60 L / (kg·min), for example, 25 L / (kg·min), 30 L / (kg·min), 35 L / (kg·min), 40 L / (kg·min), 45 L / (kg·min), 50 L / (kg·min), 55 L / (kg·min), 60 L / (kg·min), etc., and the temperature gradient is controlled at ±1.5°C / min.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] (1) The preparation method of the DTY spindle provided by the present invention introduces the steps of false twisting and heat setting, which synergistically enhance the efficiency and greatly reduce the thermal shrinkage of the polyester yarn;

[0050] (2) The preparation method of the DTY spindle provided by the present invention improves the dyeing performance of the polyester yarn, enhances the dyeing uniformity of the polyester yarn, and reduces the risk of layer difference. DETAILED DESCRIPTION

[0051] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0052] Example 1

[0053] This embodiment provides a method for preparing a DTY spindle from FDY yarn (300D / 96F), which is performed on a texturing machine with a machine operating speed of 350 m / min as follows:

[0054] S1. Feeding: Place the FDY yarn bobbin on the yarn rack and guide the yarn into the texturing machine through the yarn guide;

[0055] S2 preheating: using a non-contact heating method to preheat the raw yarn to 220 ℃;

[0056] S3 stretching: by controlling the speed difference between the first roller and the second roller to achieve the FDY yarn stretching, the stretching ratio is 1.02 times;

[0057] S4. False twist: The preheated FDY yarn was twisted and untwisted using a false twister with a D / Y ratio of 1.6, a K value of 1.05, a false twist temperature of 220°C, and a time of 3 s.

[0058] S5. Heat setting: After untwisting, the yarn is set by non-contact heating at 190°C for 10 seconds while controlling the overfeed ratio to 1.02 to relax the yarn.

[0059] S6. Cooling: After heat setting, it enters the cooling plate for cooling;

[0060] S7. Mesh treatment: The filaments were blown with compressed air nozzles at a pressure of 0.2 MPa and an overfeed rate of 1.01%.

[0061] S8. Oiling: Use oil tanker to oil the yarn and control the oil content of the yarn to 2.5%;

[0062] S9. The DTY yarn is wound by the traverse guide rod and the winding roller (winding ratio is 5.4);

[0063] S10. Cone loosening: Taihe precision winder with constant tension control is used for cone loosening: the line speed of the equipment is 500m / min, the cone loosening tension is 8-10cN, and the density is 0.4g / cm 3 .

[0064] Example 2

[0065] This embodiment provides a method for pre-dyeing treatment of FDY yarn.

[0066] The difference from Example 1 is that the FDY yarn specification in this example is 150D / 48F, the tension of the loosening cone is 9-12cN, and the density is 0.42g / cm 3 .

[0067] Example 3

[0068] This embodiment provides a method for pre-dyeing treatment of FDY yarn.

[0069] The difference from Example 1 is that the FDY yarn specification in this example is 300D / 48F.

[0070] Examples 4-6

[0071] This embodiment provides a method for preparing DTY spindles from FDY yarn (300D / 96F).

[0072] The difference from Example 1 is that, in this embodiment, the heat setting temperature of step S5 is 170° C. (Example 4), 180° C. (Example 5), and 200° C. (Example 6).

[0073] Examples 7-8

[0074] This embodiment provides a method for preparing DTY spindles from FDY yarn (300D / 96F).

[0075] The difference from Example 1 is that, in this embodiment, the preheating temperature of step S2 and the false twisting temperature of step S4 are both 200° C. (Example 7) and 210° C. (Example 8).

[0076] Example 9

[0077] This embodiment provides a method for preparing a DTY spindle from FDY yarn (300D / 96F), which is performed on a texturing machine with a machine operating speed of 350 m / min as follows:

[0078] S1. Feeding: Place the FDY yarn bobbin on the yarn rack and guide the yarn into the texturing machine through the yarn guide;

[0079] S2 preheating: using a non-contact heating method to preheat the raw yarn to 220 ℃;

[0080] S3 stretching: by controlling the speed difference between the first roller and the second roller to achieve the FDY yarn stretching, the stretching ratio is 1.01 times;

[0081] S4. False twist: The preheated FDY yarn was twisted and untwisted using a false twister with a D / Y ratio of 2.0, a K value of 1.3, a false twist temperature of 220°C, and a time of 10 s.

[0082] S5. Heat setting: After untwisting, the yarn is set by non-contact heating at 180°C for 30 seconds while controlling the overfeed ratio to 1.01 to relax the yarn.

[0083] S6. Cooling: After heat setting, it enters the cooling plate for cooling;

[0084] S7. Mesh treatment: The filaments were blown with compressed air nozzles at a pressure of 0.2 MPa and an overfeed rate of 1.01%.

[0085] S8. Oiling: Use oil tanker to oil the yarn and control the oil content of the yarn to 2.8%;

[0086] S9. The DTY yarn is wound by the traverse guide rod and the winding roller (winding ratio is 5.4);

[0087] S10. Cone loosening: Taihe precision winder with constant tension control is used for cone loosening: the line speed of the equipment is 500m / min, the cone loosening tension is 8-10cN, and the density is 0.4g / cm 3 .

[0088] Comparative Example 1

[0089] This comparative example provides a method for preparing a DTY spindle from FDY yarn (300D / 96F), which is carried out on a twisting machine as follows:

[0090] S1. Yarn feeding: The FDY yarn to be twisted is introduced into the machine through the yarn feeding device. The yarn feeding device, including the guiding device, ensures that the yarn can smoothly enter the subsequent twisting process;

[0091] S2. The unwinding output yarn is unwound from the stationary yarn supply bobbin and unwound from the feed bobbin through the unwinder;

[0092] S3. First twist: The yarn enters the yarn space and the hollow spindle shaft from the upper end of the spindle, then enters the upper half of the rotating spindle rotor, and is guided out of the small hole at the end of the yarn slot of the yarn storage disk; the yarn is twisted for the first time between the yarn gate inside the hollow shaft and the small hole inside the spindle rotor;

[0093] S4 balloon formation: the first twisted yarn around the storage disk to form a balloon, supported and restricted by the balloon cover, the balloon is restricted at the apex by the pigtail-shaped yarn guide hook;

[0094] S5. Second twisting: The yarn is twisted for the second time in the outer balloon between the spindle rotor and the pigtail yarn guide hook to obtain a double twist effect;

[0095] S6. Yarn output: The twisted yarn is led out from the small hole at the end of the yarn slot of the yarn storage disk, passes through the yarn guide hook, and completes the twisting.

[0096] The twisting twist is set to 80 twists, and the twisted yarn is then vacuum steam-set at a temperature of 120°C for 20 minutes and kept warm for 30 minutes.

[0097] Comparative Examples 2-3

[0098] This comparative example provides a method for treating FDY yarn (300D / 96F) before dyeing.

[0099] The difference from Example 1 is that in this comparative example, the preheating temperature of step S2 and the false twisting temperature of step S4 are both 190° C. (Comparative Example 2) and 230° C. (Comparative Example 3).

[0100] Comparative Example 4

[0101] This comparative example provides an FDY yarn (300D / 96F) having a dry heat shrinkage of 13.4% and a boiling water shrinkage of 7.4%.

[0102] Comparative Example 5

[0103] This comparative example provides an FDY yarn (150D / 96F) having a dry heat shrinkage of 11.4% and a boiling water shrinkage of 6.8%.

[0104] Performance Testing

[0105] The performance test of the bobbins obtained after dyeing pre-treatment (after loosening) of the embodiments and comparative examples was carried out as follows:

[0106] (1) Dry heat boiling water shrinkage: tested according to the test standard of GB / T 6505-2017;

[0107] (2) Dyeing uniformity: After weaving the inner, middle and outer layers of yarn, the yarn is tested and rated using a datacolor instrument;

[0108] The test results are shown in Table 1:

[0109] Table 1

[0110]

[0111] It can be seen from the embodiments and performance tests that the pretreatment method provided by the present invention can greatly reduce the dry heat shrinkage and boiling water shrinkage of FDY yarn. Among them, the dry heat shrinkage of 300D / 96F is reduced from 13.4% to below 8.2%, and the optimal value can reach below 7.6%. The boiling water shrinkage is reduced from 7.4% to below 4%, and the optimal value can reach below 3.4%. The dyeing uniformity is high, and its dyeing uniformity rating is 4.5 / 5. The dry heat shrinkage of 150D / 96F is reduced from 11.4% to 5.6%, and the boiling water shrinkage is reduced from 6.8% to 3.2%. The dyeing uniformity is high, and its dyeing uniformity rating is 4.5 / 5.

[0112] It should be noted that the faster the winding speed, the shorter the processing time in the hot box, and the higher the corresponding dry heat shrinkage rate and boiling water yield.

[0113] From the comparison between Example 1 and Examples 4-6, it can be seen that when the heat setting temperature of the present invention is within 180-190°C, the setting effect on the yarn after false twist is the best, which can further relax the yarn, eliminate residual stress, stabilize the crystal structure, and thus reduce the thermal shrinkage of the polyester yarn.

[0114] From the comparison between Example 1 and Comparative Example 1, it can be seen that the pre-treatment method provided by the present invention is a treatment for yarn, and the dry heat and boiling water shrinkage rates of the inside, middle and outside of the yarn can be kept consistent after winding. The green color of the yarn is more uniform and stable during dyeing, and the color spots and layer differences are greatly reduced. The one-time dyeing success rate is >85%; while in the twisting and setting process specified in Comparative Example 1, the inside, middle and outside of the cheese yarn are inconsistent due to the inconsistent steam setting contact, resulting in deviations in the dry heat and boiling water shrinkage rates, and since long-term high temperature and high pressure will damage the strength of the material, the setting time is relatively short, resulting in differences in shrinkage rates of the inner and outer layers of the cheese yarn, and color spots and layer differences are also prone to occur during the dyeing process. The one-time dyeing success rate is about 65-75%.

[0115] From the comparison between Example 1 and Comparative Examples 2-3, it can be seen that when the false twisting temperature is 200-220°C, the yarn can form a stable curl structure, which can destroy the high orientation structure of the yarn as much as possible and reduce the internal stress of the fiber.

[0116] The applicant declares that the present invention is illustrated by the above-described embodiments, but the present invention is not limited to these embodiments. This does not mean that the present invention must rely on these embodiments in order to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for raw materials in the present invention, additions of auxiliary ingredients, and selection of specific methods, etc., fall within the scope of protection and disclosure of the present invention.

Claims

1. A method for preparing a DTY silk ingot, characterized in that: The preparation method comprises: preheating, stretching, false twisting, heat setting, cooling, oiling and winding the raw yarn in sequence to obtain the DTY spindle, wherein the false twisting temperature is 200-220°C.

2. The method for preparing the DTY silk ingot according to claim 1, wherein: The false twisting time is 3-10s.

3. The method for preparing a DTY silk ingot according to claim 1 or 2, characterized in that: In the false twisting, the D / Y ratio is 1.6-2.0, and the K value is 1.05-1.

3.

4. The method for preparing a DTY silk ingot according to any one of claims 1 to 3, characterized in that: The heat setting temperature is 180-190°C, and the preferred time is 10-30s; Preferably, the overfeed ratio of the heat setting is 1.01-1.

02.

5. The method for preparing a DTY silk ingot according to any one of claims 1 to 4, characterized in that: The stretching ratio is 1.0-1.05 times.

6. The method for preparing a DTY silk ingot according to any one of claims 1 to 5, characterized in that: The oil content of the oiled yarn is 2.2-2.8%.

7. The method for preparing a DTY silk ingot according to any one of claims 1 to 6, characterized in that: The raw yarn is FDY raw yarn.

8. A DTY ingot prepared by the method for preparing a DTY ingot according to any one of claims 1 to 7.

9. Use of the preparation method of the DTY spindle according to any one of claims 1 to 7 in reducing the thermal shrinkage of FDY polyester yarn and improving dyeing uniformity.

10. A dyeing method, characterized in that: The dyeing method comprises: loosening the DTY yarn spindle according to claim 8, dyeing, washing, fixing and finishing.

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