A method for producing a down blended yarn

Abstract

The present application relates to the field of spinning technology, and particularly relates to a preparation method of down blended yarn, which comprises pretreatment of down fibers, cotton blending and drawing, roving and spinning. The present application adopts weak alkali solution of certain concentration to soak and wash the down fibers, so as to remove the peculiar smell of down and partial grease on the surface of down fibers; then, oiling treatment is performed to improve the friction and cohesion of down fibers and control the water content of down within a proper range. The treated down is evenly scattered on the cotton web after the carding process by using the designed uniform opening and metering down scattering device, and then drawing is performed to wrap the down in the cotton sliver, so as to eliminate flying and falling of the down and reduce the loss rate of down fibers. The down blended yarn is prepared by using the spinning process of "low weight per unit and low speed", so as to solve the problems of difficulty in webbing of down fibers, much flying, easy deterioration of sliver and the like in the prior art.

Description

Technical Field

[0001] This invention relates to the field of spinning technology, and in particular to a method for preparing down-blend yarn. Background Technology

[0002] Down fiber is a natural protein fiber with excellent properties such as fluffiness, softness, warmth, and water repellency, making it a high-quality textile raw material, mainly used as a filling material in textiles. Blending down with other spinnable materials to form yarn and then weaving it into down fabrics results in fabrics that are both warm and lightweight, meeting consumer demands for functionality, comfort, and style. However, due to the fluffy structure and smooth surface of down fibers, the coefficient of friction is low, resulting in poor fiber cohesion. Furthermore, the short overall fiber length and poor uniformity lead to problems in actual spinning production, such as difficulty in web formation, excessive fly waste, and evenness. This presents significant challenges in processing and production management, resulting in poor spinning performance and greatly limiting its widespread application in the textile industry.

[0003] Patent No. CN1920141A discloses a method for producing medium-count down blended yarn. After pretreatment of the down, it is blended with textile fiber raw materials and subjected to humidification balancing treatment, causing the down to change from a hydrophobic state to a hydrophilic state, making it suitable for spinning on conventional ring spinning equipment. Patent No. CN110644092A discloses a down blended yarn and its spinning method. It uses wool oil and an antistatic agent to pretreat the down fibers, solving the problems of fly and lint during production. The treated down is then blended with functional viscose fibers and cotton fibers, drawn, and spun to fix the down clusters onto the yarn, producing down blended yarn that can be widely used in various thermal fabrics. Patent No. CN118756396A pretreats down and heat-generating acrylic fibers, and produces down blended yarn by blending down, heat-generating acrylic fibers, and lyocell fibers. The above invention improves down performance by using wool oil and antistatic agents to pre-treat down for a long time (≥24 hours). The fly phenomenon during yarn preparation is improved, but the odor and surface oil of down cannot be removed. The problem of a large amount of down falling during the combing process after blending with cotton is still not solved. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing down-blended yarn. This method involves soaking and washing the down in a weak alkaline solution of a certain concentration to remove odors and surface grease. Following this, an oiling treatment improves the friction and cohesion of the down fibers and controls the down's moisture content within a suitable range. A uniform opening and metering down-shedding device is designed to evenly distribute the treated down onto the cotton web after the carding process, where it is drawn into slivers, encasing the down within the slivers and preventing fly and lint shedding. A low-quantity, low-speed spinning process is employed to prepare the down-blended yarn, solving problems in existing technologies such as difficulty in forming a web, excessive fly, easy deterioration of yarn evenness, and high down shedding rate.

[0005] To achieve the above-mentioned objectives, the present invention employs the following steps: S1, Pretreatment of down fibers Place down fibers in an alkaline solution with a pH of 8-10, soak and wash for 10-20 minutes, dehydrate, then wash with soft water at 30-40℃ until neutral, and then dehydrate, oil, dehydrate, and dry for later use.

[0006] Preferably, the alkaline additive in the alkaline solution is one or more of sodium hydroxide, sodium carbonate, and sodium bicarbonate.

[0007] Preferably, the mass ratio of down fibers to alkaline solution during the soaking and washing process is controlled at 1:20 to 30.

[0008] Preferably, the oiling agent is selected from the same type used for functional fibers, and the blending ratio is adjusted to achieve the compatibility between down and functional fibers.

[0009] Furthermore, the oiling agent is a mixture of HONOL GA and HONOL MGR, viscose fiber oiling agents produced by Takemoto Oils Co., Ltd. of Japan, wherein the mass ratio of HONOL GA to HONOL MGR is 6-7:3-4.

[0010] Preferably, the concentration of the oil bath is 6-10 g / L, the mass ratio of down fiber to oil bath is controlled at 1:15-20, the oiling temperature is 40-50℃, and the time is 3-10 min.

[0011] Since the solvent in the oil bath is water, the down fibers absorb the oil on their surface and are then dehydrated, which is beneficial for subsequent drying.

[0012] Preferably, the moisture content of the dried down fibers is controlled at 15-30%.

[0013] S2, Cotton blend and drawing The blended functional fibers are fed into a carding machine via a feed roller, and after being carded in the cylinder, they enter the doffer to form a cotton web. The pre-treated down fibers do not undergo opening and cleaning. After opening, they are evenly scattered on the cotton web through a metering and shedding device, and then formed into a sliver by the front pressure roller. The sliver is then drawn and combined in the drawing process to obtain the blended sliver.

[0014] Preferably, the functional fiber is one or more of viscose fiber and acrylic fiber.

[0015] Preferably, the mass ratio of the pretreated down fibers to the functional fibers is controlled at 3-15:85-97.

[0016] Preferably, in the carding machine, the licker-in speed is 600-800 rpm, the cylinder speed is 300-350 rpm, the interval between the flats and the cylinder is 8, 8, 7, 7, 8, the doffer speed is 65-75 m / min, and the weight of the sliver is 19-21 g / 5m.

[0017] Preferably, in the drawing process, the front roller speed is 220-300 m / min, and the hardness of the leather roller is adjusted to 80-90 degrees, which increases the fiber holding force and improves the evenness rate. After the drawing process, the weight of the sliver is 18-20 g / 5m.

[0018] Because down fibers have a low coefficient of friction and poor cohesion, a two-stage drawing process with sequential drafting is used in the drawing process. Furthermore, since cotton slivers contain down fibers and have high loft, excessive doubling can easily cause fiber congestion in the drafting zone, leading to frequent equipment shutdowns. Therefore, the number of doubling fibers in a single drawing stage should be set to 5-6, and the total draft ratio should be controlled between 5.5 and 6.5. The core objective of these process parameters is to optimize the evenness of the sliver and reduce draft unevenness.

[0019] S3, roving and spinning After the wool tops are processed through roving and spinning processes, down-blend yarn is obtained.

[0020] In roving, due to the inherent characteristics of down fibers, the mixed sliver is prone to loosening, leading to problems such as poor drafting, uneven yarn distribution, and increased breakage rate during processing. Therefore, it is necessary to reduce the production speed in the roving process to avoid the risk of breakage induced by tension fluctuations. In addition, given the fluffy and difficult-to-twist characteristics of down fibers, their twisting efficiency is relatively low. Based on practical production experience, the roving twist coefficient needs to be increased by 10-15% compared to ordinary yarn, controlled at 30-35 twists / m, and the roving basis weight is 5-8 g / 10m.

[0021] In the spinning process, due to the fluffy nature of down fibers, their easy loosening, and low twisting efficiency, traditional ring spinning technology struggles to effectively control the fiber sliver, easily leading to problems such as uneven drafting, high breakage rate, and poor evenness. Therefore, we adopt compact spinning in the spinning process. The cohesive effect of compact spinning tightens the sliver, reducing fiber dispersion and slippage, providing stronger fiber control, reducing the impact of tension fluctuations during production, decreasing the frequency of breakage and downtime, improving production continuity, and resulting in smaller coefficients of variation for various yarn performance indicators and more stable quality. Simultaneously, to ensure smooth spinning, the spinning speed should be slightly reduced. Furthermore, to improve yarn strength, the twist coefficient should be 10-15% higher than ordinary varieties, controlled at 750-850 twists / m, with a spinning frame draft of 28-35 times, a back zone draft of 1.1-1.2 times, and a yarn count of 20-32S.

[0022] Due to the adoption of the above technical solution, the technical effects of the present invention are as follows: 1. The method of this invention successfully overcomes the inherent defect that down fibers are difficult to spin, realizes efficient blending between down fibers and functional fibers, and significantly improves the quality of yarn.

[0023] 2. This invention does not use the method of directly mixing down fibers and functional fibers for spinning. Instead, the functional fibers are first carded to form a cotton web, and then the down fibers are evenly placed on the cotton web by a metering and shedding device. The cotton web wraps the down fibers, thereby reducing lint shedding, greatly improving the utilization rate of raw materials, and eliminating the problems of difficulty in forming a web, excessive fly waste, and deterioration of yarn evenness that occur when down and functional fibers are mixed before carding. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of step S2 in this invention. Detailed Implementation

[0025] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0026] Example 1: A method for preparing down-blend yarn S1, Pretreatment of down fibers Take down fibers and place them in a sodium bicarbonate solution with a pH of 9. After soaking and washing for 15 minutes, dehydrate them and then wash them with soft water at 30℃ until neutral. After dehydration, oiling, dehydration, and drying, they are ready for use.

[0027] The length of the down fibers ranges from 10 to 12 mm, and the length uniformity is 55%.

[0028] During the soaking and washing process, the mass ratio of down fibers to sodium bicarbonate solution is controlled at 1:20.

[0029] The oiling agent is a mixture of HONOL GA and HONOL MGR produced by Takemoto Oils Co., Ltd. of Japan, wherein the mass ratio of HONOL GA to HONOL MGR is 6:4.

[0030] The concentration of the oil bath for oiling is 8 g / L, the mass ratio of down fiber to oil bath is controlled at 1:20, the oiling temperature is 45℃, and the time is 5 min.

[0031] The moisture content of the dried down fibers is controlled at 15%.

[0032] S2, Cotton blend and drawing The blended functional fibers are fed into a carding machine via a feed roller, and after being carded in the cylinder, they enter the doffer to form a cotton web. The pre-treated down fibers do not undergo opening and cleaning. After opening, they are evenly scattered on the cotton web through a metering and shedding device, and then formed into a sliver by the front pressure roller. The sliver is then drawn and combined in the drawing process to obtain the blended sliver.

[0033] The functional fibers are antibacterial viscose fiber and acrylic fiber, wherein the antibacterial viscose fiber is 1.33dtex×38mm and the acrylic fiber is 1.67dtex×38mm.

[0034] The mass ratio of the pretreated down fiber, antibacterial viscose fiber, and acrylic fiber is controlled at 3:32:65.

[0035] In the carding machine, the licker-in speed is 700 rpm, the cylinder speed is 320 rpm, the interval between the flats and the cylinder is 8, 8, 7, 7, 8, the doffer speed is 70 m / min, and the weight of the sliver is 20 g / 5 m.

[0036] In the drawing process, the front roller speed is 260m / min, the hardness of the leather roller is adjusted to 85 degrees, and the weight of the sliver after the drawing process is 19g / 5m.

[0037] The drawing process employs a two-stage drawing and stretching process. In the first drawing stage, the number of folded strands should preferably be set to 6, with a total stretching ratio of 5.9 and a back zone stretching ratio of 1.7. In the second drawing stage, the number of folded strands should preferably be set to 6, with a total stretching ratio of 6.2 and a back zone stretching ratio of 1.3.

[0038] S3, roving and spinning After the wool tops are processed through roving and spinning processes, down-blend yarn is obtained.

[0039] The roving twist coefficient is 32 twists / m, and the roving weight is 6g / 10m.

[0040] The yarn twist coefficient is controlled at 800 twists / m, the yarn draft is 30 times, the back zone draft is 1.1 times, and the yarn count is 24S.

[0041] Testing showed that the down-blend yarn prepared using Example 1 meets the main performance requirements for everyday wear fabrics. The finished yarn has a breaking strength of 12.5 cN / tex, a breaking strength coefficient of variation of 11%, a linear density coefficient of variation of 2.2%, a yarn evenness coefficient of variation of 14.5%, and 48 neps / 1000m. According to the FZ / T 12078-2023 standard for "Viscose Fiber and Acrylic Blend Colored Spun Yarn," it meets the quality requirements for first-class yarn. The raw material loss rate of the down fiber is 0.7%.

[0042] Example 2: A method for preparing down-blend yarn S1, Pretreatment of down fibers Take down fibers and place them in a sodium hydroxide solution with a pH of 10. After soaking and washing for 10 minutes, dehydrate them and then wash them with soft water at 35℃ until neutral. After dehydration, oiling, dehydration, and drying, they are ready for use.

[0043] The length of the down fibers ranges from 10 to 12 mm, and the length uniformity is 55%.

[0044] During the soaking and washing process, the mass ratio of down fibers to sodium hydroxide solution is controlled at 1:25.

[0045] The oiling agent is a mixture of HONOL GA and HONOL MGR produced by Takemoto Oils Co., Ltd. of Japan, wherein the mass ratio of HONOL GA to HONOL MGR is 7:3.

[0046] The concentration of the oil bath for oiling is 7 g / L, the mass ratio of down fiber to oil bath is controlled at 1:23, the oiling temperature is 40℃, and the time is 7 min.

[0047] The moisture content of the dried down fibers is controlled at 28%.

[0048] S2, Cotton blend and drawing The blended functional fibers are fed into a carding machine via a feed roller, and after being carded in the cylinder, they enter the doffer to form a cotton web. The pre-treated down fibers do not undergo opening and cleaning. After opening, they are evenly scattered on the cotton web through a metering and shedding device, and then formed into a sliver by the front pressure roller. The sliver is then drawn and combined in the drawing process to obtain the blended sliver.

[0049] The functional fibers are mite-resistant viscose fiber and acrylic fiber, wherein the mite-resistant viscose fiber is 1.33dtex×38mm and the acrylic fiber is 1.67dtex×38mm.

[0050] The mass ratio of the pretreated down fiber, anti-mite viscose fiber, and acrylic fiber is controlled at 10:50:40.

[0051] In the carding machine, the licker-in speed is 600 rpm, the cylinder speed is 300 rpm, the gap between the flats and the cylinder is 8, 8, 7, 7, 8, the doffer speed is 65 m / min, and the weight of the sliver is 19 g / 5 m.

[0052] In the drawing process, the front roller speed is 220m / min, the hardness of the leather roller is adjusted to 80 degrees, and the weight of the sliver after the drawing process is 18g / 5m.

[0053] The drawing process employs a two-stage drawing process with sequential drawing; the number of folded strands in the first drawing stage should preferably be set to 6, with a total drawing ratio of 5.8 and a back zone drawing ratio of 1.7; the number of folded strands in the second drawing stage should preferably be set to 6, with a total drawing ratio of 6.2 and a back zone drawing ratio of 1.3.

[0054] S3, roving and spinning After the wool tops are processed through roving and spinning processes, down-blend yarn is obtained.

[0055] The roving twist coefficient is 30 twists / m, and the roving weight is 5g / 10m.

[0056] The yarn twist coefficient is controlled at 750 twists / m, the yarn draft is 28 times, the back zone draft is 1.1 times, and the yarn count is 20S.

[0057] Testing showed that the down-blend yarn prepared in Example 2 met the requirements for everyday wear fabrics. The finished yarn had a breaking strength of 12.8 cN / tex, a breaking strength coefficient of variation of 10.5%, a linear density coefficient of variation of 2%, a yarn evenness coefficient of variation of 12.5%, and 44 neps / 1000m. According to the FZ / T 12078-2023 "Viscose Fiber and Acrylic Blend Colored Spun Yarn" quality standard, it met the requirements for first-class yarn quality. The raw material loss rate of down fiber was 0.9%.

[0058] Example 3: A method for preparing down-blend yarn S1, Pretreatment of down fibers Take down fibers and place them in a sodium carbonate solution with a pH of 8. After soaking and washing for 18 minutes, dehydrate them and then wash them with soft water at 32℃ until neutral. After dehydration, oiling, dehydration, and drying, they are ready for use.

[0059] The length of the down fibers ranges from 10 to 12 mm, and the length uniformity is 55%.

[0060] During the soaking and washing process, the mass ratio of down fibers to sodium bicarbonate solution is controlled at 1:30.

[0061] The oiling agent is a mixture of HONOL GA and HONOL MGR produced by Takemoto Oils Co., Ltd. of Japan, wherein the mass ratio of HONOL GA to HONOL MGR is 6.5:3.5.

[0062] The concentration of the oil bath for oiling is 6 g / L, the mass ratio of down fiber to oil bath is controlled at 1:20, the oiling temperature is 50℃, and the time is 10 min.

[0063] The moisture content of the dried down fibers is controlled at 30%.

[0064] S2, Cotton blend and drawing The blended functional fibers are fed into a carding machine via a feed roller, and after being carded in the cylinder, they enter the doffer to form a cotton web. The pre-treated down fibers do not undergo opening and cleaning. After opening, they are evenly scattered on the cotton web through a metering and shedding device, and then formed into a sliver by the front pressure roller. The sliver is then drawn and combined in the drawing process to obtain the blended sliver.

[0065] The functional fibers are antibacterial viscose fiber and acrylic fiber, wherein the antibacterial viscose fiber is 1.33dtex×38mm and the acrylic fiber is 1.56dtex×38mm.

[0066] The mass ratio of the pretreated down fiber, antibacterial viscose fiber, and acrylic fiber is controlled at 15:50:35.

[0067] In the carding machine, the licker-in speed is 800 rpm, the cylinder speed is 350 rpm, the spacing between the flats and the cylinder is 8, 8, 7, 7, 8, the doffer speed is 75 m / min, and the weight of the sliver is 21 g / 5 m.

[0068] In the drawing process, the front roller speed is 300m / min, the hardness of the leather roller is adjusted to 90 degrees, and the weight of the sliver after the drawing process is 18.5g / 5m.

[0069] The drawing process employs a two-stage drawing process with sequential drawing; the number of folded strands in the first drawing stage should preferably be set to 6, with a total drawing ratio of 5.8 and a back zone drawing ratio of 1.7; the number of folded strands in the second drawing stage should preferably be set to 6, with a total drawing ratio of 6.2 and a back zone drawing ratio of 1.3.

[0070] S3, roving and spinning After the wool tops are processed through roving and spinning processes, down-blend yarn is obtained.

[0071] The roving twist coefficient is 30.5 twists / m, and the roving weight is 5.9g / 10m.

[0072] The yarn twist coefficient is controlled at 840 twists / m, the yarn draft is 33 times, the back zone draft is 1.16 times, and the yarn count is 32S.

[0073] Testing revealed that the down-blend yarn prepared using Example 3 had a breaking strength of 12.7 cN / tex, a coefficient of variation of 10.8%, a coefficient of variation of 2.1% for linear density, a coefficient of variation of 13.6% for yarn evenness, and 46 neps per 1000m. According to the FZ / T 12078-2023 standard for "Blended Colored Yarn of Viscose Fiber and Acrylic Fiber," it meets the quality requirements for first-class yarn. The raw material loss rate of the down fiber was 0.8%.

[0074] Example 4: A method for preparing down-blend yarn S1, Pretreatment of down fibers Take down fibers and place them in a mixed solution of sodium carbonate and sodium bicarbonate at pH 9. After soaking and washing for 20 minutes, dehydrate them and then wash them with soft water at 35℃ until neutral. After dehydration, oiling, dehydration, and drying, they are ready for use.

[0075] The length of the down fibers ranges from 10 to 12 mm, and the length uniformity is 55%.

[0076] During the soaking and washing process, the mass ratio of down fibers to the sodium carbonate and sodium bicarbonate mixed solution is controlled at 1:25.

[0077] The oiling agent is a mixture of HONOL GA and HONOL MGR produced by Takemoto Oils Co., Ltd. of Japan, wherein the mass ratio of HONOL GA to HONOL MGR is 6:4.

[0078] The concentration of the oil bath for oiling is 10 g / L, the mass ratio of down fiber to oil bath is controlled at 1:20, the oiling temperature is 45℃, and the time is 6 min.

[0079] The moisture content of the dried down fibers is controlled at 20%.

[0080] S2, Cotton blend and drawing The blended functional fibers are fed into a carding machine via a feed roller, and after being carded in the cylinder, they enter the doffer to form a cotton web. The pre-treated down fibers do not undergo opening and cleaning. After opening, they are evenly scattered on the cotton web through a metering and shedding device, and then formed into a sliver by the front pressure roller. The sliver is then drawn and combined in the drawing process to obtain the blended sliver.

[0081] The functional fiber is an antibacterial viscose fiber, wherein the antibacterial viscose fiber is 1.67 dtex × 38 mm.

[0082] The mass ratio of pretreated down fibers to antibacterial viscose fibers is controlled at 10:90.

[0083] In the carding machine, the licker-in speed is 800 rpm, the cylinder speed is 350 rpm, the spacing between the flats and the cylinder is 8, 8, 7, 7, 8, the doffer speed is 75 m / min, and the weight of the sliver is 21 g / 5 m.

[0084] In the drawing process, the front roller speed is 300m / min, the hardness of the leather roller is adjusted to 90 degrees, and the weight of the sliver after the drawing process is 20g / 5m.

[0085] The drawing process employs a two-stage drawing process with sequential drawing; the number of folded strands in the first drawing stage should preferably be set to 6, with a total drawing ratio of 5.8 and a back zone drawing ratio of 1.7; the number of folded strands in the second drawing stage should preferably be set to 6, with a total drawing ratio of 6.2 and a back zone drawing ratio of 1.3.

[0086] S3, roving and spinning After the wool tops are processed through roving and spinning processes, down-blend yarn is obtained.

[0087] The roving twist coefficient is 35 twists / m, and the roving weight is 7.5g / 10m.

[0088] The yarn twist coefficient is controlled at 850 twists / m, the yarn draft is 35 times, the back zone draft is 1.2 times, and the yarn count is 32S.

[0089] Testing revealed that the down-blend yarn prepared using Example 4 had a breaking strength of 12.9 cN / tex, a coefficient of variation of 10.1%, a coefficient of variation of 1.9% for linear density, a coefficient of variation of 12.2% for yarn evenness, and 41 neps / 1000m. According to the FZT 12003-2025 standard for "Viscose Fiber Natural Yarn", it meets the quality requirements for first-class yarn. The raw material loss rate of the down fiber was 0.8%.

[0090] Comparative Example 1: Using a representative example, Comparative Example 1 differs from Example 1 in step S2, while the rest is identical to Example 1. Step S2 of Comparative Example 1 is as follows: After pretreatment, the down fibers are not opened and cleaned. They are mixed with functional fibers and then fed into a carding machine through a feed roller. After being carded in the cylinder, they enter the doffer to form a cotton web. Then, they are formed into a sliver by the front pressure roller. Finally, they are drawn and combined in the drawing process to obtain the mixed sliver.

[0091] Using Comparative Example 1, the breaking strength of the finished yarn was 11.8 cN / tex, the coefficient of variation for breaking strength was 13%, the coefficient of variation for linear density was 2.3%, the coefficient of variation for yarn evenness was 15.6%, and the number of neps per kilometer was 82. The raw material loss rate of down fiber was 7.2%.

[0092] Comparative Example 2: The representative Example 1 was used. The difference between Comparative Example 2 and Example 1 is that the down fibers were not pretreated, but the other steps were the same as those in Comparative Example 1.

[0093] Using Comparative Example 2, the breaking strength of the finished yarn was 12.0 cN / tex, the coefficient of variation for breaking strength was 12.5%, the coefficient of variation for linear density was 2.1%, the coefficient of variation for yarn evenness was 15.2%, and the number of neps per kilometer was 76. The raw material loss rate of down fiber was 8.3%.

[0094] Unless otherwise specified, all proportions and percentages mentioned in this invention are mass proportions and mass percentages; all raw materials are commercially available.

[0095] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing down-blend yarn, characterized in that, The preparation method includes pretreatment of down fibers, cotton blending and drawing, roving and spinning; The blended cotton sliver is formed by feeding the blended functional fibers into a carding machine via a feed roller, carding them in a cylinder, and then entering a doffer to form a cotton web. The pre-treated down fibers do not undergo opening and cleaning. After opening, they are evenly scattered onto the cotton web by a metering and shedding device, and then formed into a sliver by a front pressure roller. The sliver is then drawn and combined to obtain the blended sliver. In the carding machine, the speed of the licker-in roller is 600-800 rpm, the speed of the cylinder is 300-350 rpm, the interval between the flats and the cylinder is 8, 8, 7, 7, 8, the doffer speed is 65-75 m / min, and the weight of the sliver is 19-21 g / 5m. In the drawing process, the front roller speed is 220-300 m / min, the hardness of the leather roller is adjusted to 80-90 degrees, and the weight of the sliver after the drawing process is 18-20 g / 5m. In the drawing process, the number of folded slivers in a single drawing pass is set to 5 to 6, and the total draw ratio is controlled at 5.5 to 6.5 times. The pretreatment of the down fiber is as follows: take the down fiber and place it in an alkaline solution with a pH of 8 to 10, soak and wash for 10 to 20 minutes, dehydrate and then wash with soft water at 30 to 40°C until neutral, and then dehydrate, oil, dehydrate and dry for later use. The moisture content of the dried down fibers is controlled at 15-30%. The mass ratio of pretreated down fibers to functional fibers is controlled at 3-15:85-97. The roving and spinning are obtained by sequentially processing wool slivers through roving and spinning processes to obtain down-blend yarn. The roving twist coefficient is controlled at 30-35 twists / m, and the roving weight is 5-8g / 10m; The spinning process adopts compact spinning, with the yarn twist coefficient controlled at 750-850 twists / m, the spinning machine draft at 28-35 times, the back zone draft at 1.1-1.2 times, and the yarn count at 20-32S.

2. The method for preparing a down-blend yarn according to claim 1, characterized in that, The alkaline additive in the alkaline solution is one or more of sodium hydroxide, sodium carbonate, and sodium bicarbonate. During the soaking and washing process, the mass ratio of down fibers to alkaline solution is controlled at 1:20 to 30.

3. The method for preparing a down-blend yarn according to claim 1, characterized in that, The concentration of the oil bath for oiling is 6-10 g / L, the mass ratio of down fiber to oil bath is controlled at 1:15-20, the oiling temperature is 40-50℃, and the time is 3-10 min.

4. The method for preparing a down-blend yarn according to claim 1, characterized in that, The functional fiber is one or more of viscose fiber and acrylic fiber.

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