Self-curling high-bulkiness yarn based on high-shrinkage differential fiber blending and preparation method thereof

Abstract

The application provides a self-curling high-bulkiness yarn based on high-shrinkage differential fiber blending and a preparation method thereof, and belongs to the technical field of yarns.The yarn is composed of three-component fiber blending of component A, component B and component C, the yarn has a radial gradient distribution trend, component A is located at the core, component B is located at the outer layer and is in a curved arch state, which is beneficial to forming a three-dimensional support skeleton structure, and component C is filled in the skeleton gap;the hierarchical control of fiber friction coefficients is realized through differential spinning oil application, the radial gradient distribution is formed by combining fiber length difference design and step-by-step sliver blending strategy, after the spinning forming, wet heat treatment is carried out to stimulate shrinkage, and then soft finishing and drying are carried out to obtain the finished yarn;the three-dimensional skeleton is constructed by using the curved arch behavior of rigid fibers under the action of shrinkage stress, which is beneficial to improving the compression resilience performance of the bulkiness structure of the yarn.

Description

Technical Field

[0001] This invention belongs to the field of yarn technology and relates to a self-crimping high-loft yarn based on high shrinkage difference fiber blend and its preparation method. Background Technology

[0002] High-loft yarns are widely used in sweaters, wool yarns, and home textiles due to their excellent warmth, lightweight feel, and soft hand texture. Currently, the main industrial technology for achieving yarn loft is the high-shrinkage fiber blended bulky yarn technology. The principle is to blend high-shrinkage fibers with low-shrinkage fibers in a certain proportion. After heat treatment, the high-shrinkage fibers shrink, driving the low-shrinkage fibers to be pushed and arched to form a loop-like structure, thereby increasing the yarn volume and improving its loft.

[0003] However, in existing high-shrinkage blended bulky yarn technology, the low-shrinkage component is usually made of soft fibers (such as ordinary acrylic fiber, fine denier polyester, etc.), which form a disordered microscopic "soft loop" structure after heat treatment. Although this type of soft loop structure has a good feel, it has an inherent defect of poor pressure resistance and flatness: during long-term wear and repeated washing, the loops formed by soft fibers gradually collapse due to insufficient bending recovery force. The free space inside the yarn is continuously compressed, and the fluffiness is difficult to effectively rebound, resulting in obvious "hardening after long-term wear" problems in sweater products, which seriously affects the product's service life and wearing experience.

[0004] In conventional high-loft, soft yarn designs, soft, low-shrinkage fibers are typically preferred to avoid itching and a rough feel. Therefore, high-rigidity fibers are less commonly used in the selection of materials for high-shrinkage blended bulky yarns. This conventional design approach, to some extent, limits the solutions to the problem of maintaining yarn loft. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide a self-crimping, high-loft yarn based on a high-shrinkage-difference fiber blend and its preparation method.

[0006] In a first aspect, the present invention provides a self-crimping high-loft yarn based on a high-shrinkage fiber blend, wherein the yarn is composed of a blend of three-component fibers: component A, component B and component C.

[0007] Component A is high-shrinkage polypropylene terephthalate short fiber with a boiling water shrinkage rate ≥35%, a dry breaking elongation rate of 20%-60%, and an average cutting length of 35-40 mm.

[0008] Component B is ramie staple fiber or high-modulus modified polyester staple fiber, with a flexural modulus ≥2.0 GPa, boiling water shrinkage ≤5%, linear density of 1.5-3.0 dtex, and an average cutting length 5%-20% longer than that of component A;

[0009] Component C is either fine denier hollow acrylic fiber or cashmere.

[0010] After being subjected to wet heat treatment, the yarn forms a radial gradient distribution structure. Component A is located in the yarn core, component B is located in the outer layer of the yarn and forms a three-dimensional support skeleton structure in a curved and arched state, and component C fills the gaps in the skeleton structure.

[0011] This invention employs a three-component tiered design consisting of component A, component B, and component C. Each of the three components plays a different mechanical role in the yarn. A radial gradient distribution is achieved through the manufacturing process, and the three components work synergistically to form a three-dimensional fluffy structure with compressive resilience after being stimulated by humid heat.

[0012] Component A, acting as the kinetic phase, provides axial shrinkage driving force during the thermal activation process. Its boiling water shrinkage rate is ≥35%, providing shrinkage power for yarn structure reconstruction. Component A is a high-shrinkage polypropylene terephthalate staple fiber, which inherently possesses good elastic recovery properties, contributing to the yarn's elastic recovery function while providing shrinkage driving force. Controlling its dry breaking elongation within the range of 20%-60% aims to reduce the risk of fiber brittle fracture interrupting shrinkage force transmission during shrinkage. Component B, selected from ramie staple fiber or high-modulus modified polyester staple fiber, serves as the skeleton phase. Its flexural modulus is ≥2.0 GPa, and its boiling water shrinkage rate is ≤5%. During thermal activation, its own shrinkage amplitude is small, and it tends to bend and arch under the axial shrinkage stress of component A. Controlling the linear density of component B within the range of 1.5-3.0 dtex helps reduce the potential itching sensation caused by rigid fibers. Component C is either fine denier hollow acrylic fiber or cashmere. As a filler phase, it passively fills the gaps in the skeleton opened by component B, encapsulating the rigid fibers and helping to improve the surface feel of the yarn. Regarding the ratio of the three components, if the proportion of component A is too low, the shrinkage driving force may be insufficient; if the proportion is too high, the yarn may feel stiff due to excessive shrinkage. If the proportion of component B is too low, the skeleton support effect is limited; if the proportion is too high, it may affect the softness of the yarn. Component C, within the set range, helps to fully fill the gaps in the skeleton and encapsulate the rigid fibers.

[0013] Regarding the formation of radial gradient distribution, this invention achieves this through the synergistic control of friction coefficient design, fiber length difference design, and step-by-step blending strategy. The radial position of fibers during drafting and twisting is related to factors such as their surface friction coefficient, bending stiffness, and fiber length. Generally, fibers with lower surface friction coefficients and shorter lengths tend to migrate towards the yarn axis; while fibers with higher surface friction coefficients, greater bending stiffness, and relatively longer lengths are more likely to be distributed in the outer layer of the yarn. This invention controls this from three levels: First, at the friction coefficient level, a smoothing spinning oil is applied to component A to reduce its dynamic friction coefficient to 0.15-0.25, and a cohesive spinning oil is applied to component B to maintain its dynamic friction coefficient at 0.25-0.40. The difference in friction coefficients between the two provides a driving force difference for radial migration, causing the smoother component A to tend to migrate towards the yarn axis, while the component B with higher surface friction tends to be distributed in the outer layer. Secondly, regarding fiber length, the average cutting length of component B is set to be 5%-20% longer than that of component A. In the ring spinning drafting zone, longer fibers have a larger control distance between the front and rear roller nipples, experience stronger lateral pressure, and are more easily pushed to the outer edge of the yarn. This length difference design, combined with the friction coefficient programming, creates a synergistic effect. Thirdly, regarding the sliver blending strategy, component A and component C are pre-blended to form an A / C sliver during the opening / carding stage. Then, component B, which is used for sliver preparation, is introduced separately during the drawing stage. This ensures that component B's initial position is on the outer edge of the fiber bundle, which is beneficial for laying the foundation for the outer layer distribution of component B during subsequent drafting and twisting. If the three components are mixed all at once during the opening stage, component B may become embedded inside the fiber bundle during carding, which is not conducive to the formation of the core-sheath distribution. The yarn twist coefficient is set to 120-180, slightly higher than the twist coefficient level of conventional acrylic bulky yarn, which is beneficial for enhancing the radial migration trend of fibers during twisting.

[0014] In the thermally activated reconstruction of the three-dimensional skeletal structure, when the initial state blended yarn with a radial gradient distribution enters the wet heat treatment process, component A, concentrated in the core, undergoes axial shrinkage in a boiling water bath at 90-100℃, generating axial compressive stress on the entire yarn. Component B, distributed in the outer layer, due to its low boiling water shrinkage rate and high flexural modulus, tends to exhibit bending and arching behavior under this axial compressive stress, springing away from the yarn periphery. When the shrinkage force of core component A is transferred to outer component B through the frictional cohesion between fibers, if the axial compressive stress on outer component B exceeds its critical buckling load under the constraint conditions in the yarn, bending behavior similar to lateral instability may occur. Due to the high flexural modulus of component B (≥2.0 GPa), its bending radius is relatively large, and it does not tend to bend into small curled loops, but rather forms a large-scale bending and arching structure. This large-scale bending and arching is similar to a microscopic arch bridge structure, creating a relatively wide three-dimensional space within the yarn. From an overall mechanical structure perspective, a mechanical system is formed within the yarn: component A acts as a "cable," providing continuous axial shrinkage force under thermal excitation; component B acts as a "compression bar" or "supporting arch," forming a stable bending arch under shrinkage force due to its bending stiffness; component C serves as a passive filling medium, filling the gaps in the skeleton while simultaneously enveloping the exposed rigid fibers. When the yarn or fabric made from it is subjected to external compressive loads, the rigid arch structure, due to its high bending recovery force, helps to reduce compression deformation and improve the bulk recovery ability after the load is released. Compared to the "soft loop" structure formed by soft fibers in traditional bulky yarns, this arch skeleton composed of rigid fibers has a structural advantage in resisting repeated compression deformation.

[0015] The softening finishing process following wet heat treatment further improves the feel of the yarn surface and helps reduce the roughness of exposed rigid fibers in component B. A loose drying method is used to avoid compressing the already formed fluffy skeletal structure, which helps maintain the three-dimensional fluffiness of the yarn.

[0016] In the technical solution of the present invention, there are multiple levels of synergistic effects among the material selection of the above three components, the formation process of the radial gradient distribution, and the thermally excited reconstruction process.

[0017] At the material system level, components A, B, and C respectively play the functional roles of shrinkage driving, rigid support, and soft filling. The three are interdependent in the functional chain: the shrinkage force of component A preferentially acts on component B, which has sufficient flexural modulus, thus making it more conducive to forming large-scale curved arched structures. If the low-shrinkage component is a soft fiber, it will only form a conventional soft loop. The rigid skeleton formed by component B needs component C to fill and wrap the gaps; otherwise, the exposed rigid fibers will affect the tactile feel.

[0018] At the process level, the formation of radial gradient distribution relies on the synergistic effect of three methods: friction coefficient design, fiber length difference design, and step-by-step blending strategy. Step-by-step blending provides the initial spatial pre-distribution of the outer layer position for component B. The friction coefficient difference and length difference continuously provide radial migration driving force during the subsequent drafting and twisting process. The three factors work in turn during the blending, drafting, and twisting stages, which together contribute to the formation of a relatively stable core-sheath distribution structure.

[0019] At the structure-performance level, there is also a sequential synergistic relationship between the formation of radial gradient distribution and thermally activated remodeling. Radial gradient distribution provides the spatial conditions for thermal activation; when component B is more distributed in the outer layer, it is more conducive to its outward expansion under contraction stress. Thermal activation provides mechanical activation for radial distribution; the contraction force of core component A is transmitted to outer component B through the frictional cohesion between fibers, driving it to buckle and arch. The two work together in both spatial and temporal dimensions to facilitate the formation of a three-dimensional, fluffy skeletal structure.

[0020] Secondly, the present invention provides a method for preparing a self-crimping, high-loft yarn based on a high-shrinkage-difference fiber blend, the method comprising:

[0021] S1: Apply a smoothing spinning oil to component A to make its dynamic friction coefficient between 0.15 and 0.25, and apply a cohesive spinning oil to component B to make its dynamic friction coefficient between 0.25 and 0.40. Let components A, B and C stand to equilibrium to obtain pretreated component A, pretreated component B and pretreated component C respectively.

[0022] S2: Pretreatment component A and pretreatment component C are fed into the opening and cleaning equipment for preliminary opening and mixing, and then carded by a carding machine to obtain premixed A / C sliver; pretreatment component B is separately opened and carded, and then drawn and drafted to produce B sliver; the premixed A / C sliver and B sliver are combined, drawn, and then twisted and wound on a roving frame to obtain roving;

[0023] S3: The roving is fed into the spinning frame for drafting and twisting to obtain fine yarn, which is then wound through a winding machine to obtain smooth initial state blended yarn.

[0024] S4: Place the smooth initial state blended yarn in a wet heat treatment device and treat it in a boiling water bath; after dehydration, soak it in a softener for finishing, and after centrifugal dehydration, dry it with hot air to obtain a self-crimping high-loft yarn based on high shrinkage difference fiber blend.

[0025] As a preferred technical solution of the present invention, in step S1, component A is selected as high-shrinkage polypropylene terephthalate short fiber, and the boiling water shrinkage rate of component A is ≥35%.

[0026] In some optional embodiments, the dry elongation at break of component A is 20-60%, for example, it can be 20%, 24%, 28%, 32%, 36%, 40%, 44%, 48%, 52%, 56% or 60%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0027] In some alternative embodiments, the average cut length of component A is 35-40 mm, for example, it can be 35.0 mm, 35.5 mm, 36.0 mm, 36.5 mm, 37.0 mm, 37.5 mm, 38.0 mm, 38.5 mm, 39.0 mm, 39.5 mm or 40.0 mm, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0028] The smoothing spinning oil can be selected from any one of POLYFIN501, POLYFIN502, and KEOFILSR15;

[0029] In some alternative embodiments, the coefficient of kinetic friction of component A is in the range of 0.15-0.25, for example, it may be 0.15, 0.16, 0.17, 0.18, 0.19, 0.20, 0.21, 0.22, 0.23, 0.24 or 0.25, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0030] Component B is ramie short fiber or high-modulus modified polyester short fiber;

[0031] In some alternative embodiments, the linear density of the preformed component B is 1.5-3.0 dtex, for example, it can be 1.50 dtex, 1.65 dtex, 1.80 dtex, 1.95 dtex, 2.10 dtex, 2.25 dtex, 2.40 dtex, 2.55 dtex, 2.70 dtex, 2.85 dtex or 3.00 dtex, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0032] In some optional embodiments, the average cut length of the preformed component B is 5-20% longer than the average cut length of component A, for example, it can be 5.0%, 6.5%, 8.0%, 9.5%, 11.0%, 12.5%, 14.0%, 15.5%, 17.0%, 18.5% or 20.0% longer, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0033] The flexural modulus of component B is ≥2.0 GPa.

[0034] The boiling water shrinkage rate of component B is ≤5%.

[0035] The cohesive spinning oil can be KEOFILSR50;

[0036] In some alternative embodiments, the coefficient of kinetic friction of component B is in the range of 0.25-0.40, for example, it may be 0.250, 0.265, 0.280, 0.295, 0.310, 0.325, 0.340, 0.355, 0.370, 0.385 or 0.400, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0037] In some optional embodiments, the settling equilibrium temperature is 20-25°C, for example, it can be 20.0°C, 20.5°C, 21.0°C, 21.5°C, 22.0°C, 22.5°C, 23.0°C, 23.5°C, 24.0°C, 24.5°C or 25.0°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0038] In some optional embodiments, the relative humidity for settling equilibrium is 60-70%, for example, it can be 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69% or 70%, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0039] In some optional embodiments, the settling and equilibration time is 12-24 hours, for example, it can be 12.0 hours, 13.2 hours, 14.4 hours, 15.6 hours, 16.8 hours, 18.0 hours, 19.2 hours, 20.4 hours, 21.6 hours, 22.8 hours or 24.0 hours, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0040] Component C is fine denier hollow acrylic fiber or cashmere;

[0041] As a preferred technical solution of the present invention, in step S2, the mass ratio of the pretreatment component A to the pretreatment component C is (20-40):(40-70), for example, it can be (20, 22, 24, 26, 28, 30, 32, 34, 36, 38 or 40):(40, 43, 46, 49, 52, 55, 58, 61, 64, 67 or 70), but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0042] The pretreatment component B is separately cleaned and combed, and then subjected to 1-2 rounds of drawing and stretching to produce raw strip B.

[0043] In some optional embodiments, the mass ratio of the premixed A / C raw strips to the B raw strips is (70-90):(10-30), for example, it can be (70, 72, 74, 76, 78, 80, 82, 84, 86, 88 or 90):(10, 12, 14, 16, 18, 20, 22, 24, 26, 28 or 30), but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0044] In some optional embodiments, the number of folding passes in the combined processing of the premixed A / C sliver and B sliver is 2-4, for example, 2, 3 or 4 passes, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0045] In some optional embodiments, the draw ratio of the drawing machine during the folding process is 6-8 times, for example, it can be 6.0 times, 6.2 times, 6.4 times, 6.6 times, 6.8 times, 7.0 times, 7.2 times, 7.4 times, 7.6 times, 7.8 times or 8.0 times, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0046] In some alternative embodiments, the twist coefficient of the roving is 60-90, for example, it can be 60, 63, 66, 69, 72, 75, 78, 81, 84, 87 or 90, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0047] As a preferred technical solution of the present invention, in step S3, the total draft ratio of the yarn is 30-50 times, for example, it can be 30 times, 32 times, 34 times, 36 times, 38 times, 40 times, 42 times, 44 times, 46 times, 48 ​​times or 50 times, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0048] In some alternative embodiments, the twist coefficient of the yarn is 120-180, for example, it can be 120, 126, 132, 138, 144, 150, 156, 162, 168, 174 or 180, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0049] In some optional embodiments, the spindle speed of the spinning machine is 12,000-18,000 rpm, for example, 12,000 rpm, 12,600 rpm, 13,200 rpm, 13,800 rpm, 14,400 rpm, 15,000 rpm, 15,600 rpm, 16,200 rpm, 16,800 rpm, 17,400 rpm or 18,000 rpm, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0050] In some optional embodiments, the winding speed during the winding process is 600-1000 m / min, for example, it can be 600 m / min, 640 m / min, 680 m / min, 720 m / min, 760 m / min, 800 m / min, 840 m / min, 880 m / min, 920 m / min, 960 m / min or 1000 m / min, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0051] As a preferred technical solution of the present invention, in step S4, the temperature of the boiling water bath is 90-100℃, for example, it can be 90℃, 91℃, 92℃, 93℃, 94℃, 95℃, 96℃, 97℃, 98℃, 99℃ or 100℃, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0052] In some optional embodiments, the boiling water bath treatment time for the smooth initial state blended yarn is 1-15 min, for example, it can be 1.0 min, 2.4 min, 3.8 min, 5.2 min, 6.6 min, 8.0 min, 9.4 min, 10.8 min, 12.2 min, 13.6 min or 15.0 min, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0053] In some alternative embodiments, the shrinkage rate of component A reaches 80-100% of its theoretical boiling water shrinkage rate, for example, it can be 80%, 82%, 84%, 86%, 88%, 90%, 92%, 94%, 96%, 98% or 100%, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0054] In some alternative embodiments, the mass concentration of the softener is 1-5 g / L, for example, it can be 1.0 g / L, 1.4 g / L, 1.8 g / L, 2.2 g / L, 2.6 g / L, 3.0 g / L, 3.4 g / L, 3.8 g / L, 4.2 g / L, 4.6 g / L or 5.0 g / L, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0055] In some optional embodiments, the bath ratio for soaking and finishing is 1:(10-20), for example, it can be 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18, 1:19 or 1:20, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0056] In some optional embodiments, the soaking and finishing temperature is 40-60°C, for example, it can be 40°C, 42°C, 44°C, 46°C, 48°C, 50°C, 52°C, 54°C, 56°C, 58°C or 60°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0057] In some optional embodiments, the soaking and finishing time is 20-40 minutes, for example, 20 minutes, 22 minutes, 24 minutes, 26 minutes, 28 minutes, 30 minutes, 32 minutes, 34 minutes, 36 minutes, 38 minutes or 40 minutes, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0058] In some optional embodiments, the temperature of the hot air drying is 80-100°C, for example, it can be 80°C, 82°C, 84°C, 86°C, 88°C, 90°C, 92°C, 94°C, 96°C, 98°C or 100°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0059] In some optional embodiments, the hot air drying time is 10-20 min, for example, 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, 16 min, 17 min, 18 min, 19 min or 20 min, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0060] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0061] This invention introduces a specific proportion of rigid, low-shrinkage fibers as a skeleton phase into a high-shrinkage blended system. Utilizing their high flexural modulus, these fibers form a three-dimensional rigid micro-arch bridge structure under heat shrinkage stress, creating a larger space inside the yarn and improving the compressive resilience of the yarn's fluffy structure.

[0062] This invention helps reduce the itching sensation that rigid fibers may cause by controlling the linear density of component B within a fine range and using component C to fill and wrap the gaps in it, thus balancing the skeletal support function with a soft touch.

[0063] This invention achieves graded control of the fiber dynamic friction coefficient by applying differentiated spinning oil. Combined with the design of fiber cutting length difference and step-by-step mixing strategy, it utilizes the radial migration law of fibers during spinning and drafting, which is conducive to forming a radial gradient distribution of the three-component fiber sheath and core on conventional ring spinning equipment. It does not require complex covering or core-spun spinning equipment and has good process compatibility.

[0064] The three-component material system, radial gradient distribution process and thermal activation reconstruction process of this invention form a multi-level synergistic relationship. The three components are interdependent and work in succession in three dimensions: material function, spatial distribution and mechanical activation, so that the final yarn’s bulkiness and compressive resilience show a trend of multi-factor synergistic improvement. Attached Figure Description

[0065] Figure 1 This is a schematic diagram of the radial distribution of the cross-section of the smooth initial state blended yarn before wet heat treatment in Example 1;

[0066] Figure 2 This is a schematic diagram of the three-dimensional skeleton structure of the longitudinal section of the smooth initial state blended yarn after wet heat treatment in Example 1.

[0067] In the figure: 1. Pretreatment component A; 2. Pretreatment component B; 3. Pretreatment component C. Detailed Implementation

[0068] The technical solutions of the present invention will be described in detail below with reference to specific embodiments and accompanying drawings. The embodiments described herein are specific implementations of the present invention, used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary, and should not be construed as limiting the implementation methods or the scope of protection of the present invention. In addition to the embodiments described herein, those skilled in the art can employ other obvious technical solutions based on the content disclosed in the claims and specification of this application. These technical solutions include any obvious substitutions and modifications made to the embodiments described herein.

[0069] The chemical reagents used in the embodiments and comparative examples of this invention are all commercially available products and have not undergone further purification or processing.

[0070] High-shrinkage polypropylene terephthalate staple fiber: purchased from Jiangsu Zaibo New Material Technology Co., Ltd.;

[0071] Ramie short fiber: purchased from Jiaxing Huilong Ramie Industry Co., Ltd.;

[0072] High-modulus modified polyester staple fiber: purchased from Hangzhou Benma Chemical Fiber Spinning Co., Ltd.;

[0073] Polyester staple fiber with conventional bending modulus: purchased from Hangzhou Benma Chemical Fiber Spinning Co., Ltd.;

[0074] Example 1

[0075] This embodiment provides a self-crimping, high-loft yarn based on a high-shrinkage-difference fiber blend and its preparation method. The preparation method of the self-crimping, high-loft yarn based on a high-shrinkage-difference fiber blend specifically includes the following steps:

[0076] S1: High-shrinkage polypropylene terephthalate staple fiber with boiling water shrinkage rate ≥35%, dry breaking elongation rate 40%, and average cutting length 38mm was prepared by using a smooth spinning oil agent POLYFIN501 to bring its dynamic friction coefficient to the range of 0.22 to obtain component A. Ramie staple fiber with linear density of 2.5dtex, average cutting length 15% longer than the average cutting length of component A, flexural modulus ≥2.0GPa, and boiling water shrinkage rate ≤5% was prepared by using a cohesive spinning oil agent to bring its dynamic friction coefficient to the range of 0.35 to obtain component B. Fine denier hollow acrylic fiber was selected as component C. The three components of fiber were respectively placed in an environment of 24℃ and 68% relative humidity for 20h to obtain pretreated component A1, pretreated component B2, and pretreated component C3.

[0077] S2: Pretreatment component A1 and pretreatment component C3 are fed into the opening and mixing equipment at a mass ratio of 35:65 for initial opening and mixing, and then carded by a carding machine to obtain premixed A / C sliver; pretreatment component B2 is separately opened and carded, and then drawn and drafted once to produce B sliver; the premixed A / C sliver and B sliver are combined at a mass ratio of 85:15, and then drawn three times, with the draft ratio of the drawing frame controlled at 7.5 times, and then twisted and wound on a roving frame to obtain roving; the roving twist coefficient is controlled at 80;

[0078] S3: The roving is fed into the spinning frame for drafting and twisting to obtain the fine yarn. The total draft ratio of the fine yarn is controlled at 45 times, the twist coefficient of the fine yarn is set at 170, and the spindle speed is controlled at 17000 rpm. Then the fine yarn is wound on the winding machine at a speed of 900 m / min to obtain a smooth initial state blended yarn. Figure 1The diagram shows the smooth initial state of the blended yarn. As shown, pretreatment component A1 is concentrated in the yarn core, pretreatment component B2 is mainly distributed in the outer layer of the yarn, and pretreatment component C3 is distributed throughout the yarn cross-section and surrounds pretreatment component B2 in the outer layer region. At this time, the yarn as a whole has a tight and smooth conventional yarn shape. None of the three component fibers have shrunk or bent, the yarn diameter is small, and it has not yet shown a fluffy characteristic.

[0079] S4: Place the smooth initial state blended yarn in a wet heat treatment device and treat it in a boiling water bath at 98℃ for 12 minutes to make the shrinkage rate of component A reach 95% of its theoretical boiling water shrinkage rate; after dehydration, immerse it in a softener with a mass concentration of 4g / L, and soak and finish it at a bath ratio of 1:18 and a temperature of 55℃ for 35 minutes. After centrifugal dehydration, dry it loosely in hot air at 95℃ for 18 minutes to obtain a self-crimping high-loft yarn based on high shrinkage difference fiber blend. Figure 2 This is a schematic diagram of a self-crimping, high-loft yarn based on a high-shrinkage fiber blend. As shown in the figure, after wet heat treatment, the core pretreatment component A1 undergoes axial shrinkage, resulting in a significant reduction in fiber length and a short, densely packed, contracted state. The outer pretreatment component B2, which itself shrinks almost nothing, bends and arches outwards towards the yarn's periphery under the axial compressive stress generated by the shrinkage of the core pretreatment component A1, forming several large-scale arched structures, significantly increasing the yarn's radial dimension. The pretreatment component C3 subsequently expands and loosens, filling the gaps between adjacent arched arcs and the outer side of the arched arcs in a naturally curved state, thus enveloping the pretreatment component B2. The yarn as a whole exhibits a fluffy, full, three-dimensional shape.

[0080] Example 2

[0081] This embodiment provides a self-crimping, high-loft yarn based on a high-shrinkage-difference fiber blend and its preparation method. The preparation method of the self-crimping, high-loft yarn based on a high-shrinkage-difference fiber blend specifically includes the following steps:

[0082] S1: High-shrinkage polypropylene terephthalate short fibers with a boiling water shrinkage rate ≥35%, dry breaking elongation rate 20%, and average cutting length of 35 mm are used with a smooth spinning oil agent POLYFIN502 to achieve a dynamic friction coefficient within the range of 0.15 to obtain component A. Pre-treated component B ramie short fibers with a linear density of 1.5 dtex, an average cutting length 5% longer than the average cutting length of component A, a bending modulus ≥2.0 GPa, and a boiling water shrinkage rate ≤5% are used with a cohesive spinning oil agent to achieve a dynamic friction coefficient within the range of 0.25 to obtain component B. Cashmere is selected as component C. The three components of fibers are respectively placed in an environment with a temperature of 20℃ and a relative humidity of 60% for 12 hours to achieve static equilibrium, resulting in pretreated component A1, pretreated component B2, and pretreated component C3.

[0083] S2: Pretreatment component A1 and pretreatment component C3 are fed into the opening and mixing equipment at a mass ratio of 20:40 for initial opening and mixing, and then carded by a carding machine to obtain premixed A / C sliver; pretreatment component B2 is separately opened and carded, and then drawn and drafted twice to produce B sliver; the premixed A / C sliver and B sliver are combined at a mass ratio of 70:10, and then drawn twice, with the draft ratio of the drawing frame controlled at 6 times, and then twisted and wound on a roving frame to obtain roving; the roving twist coefficient is controlled at 60.

[0084] S3: The roving is fed into the spinning frame for drafting and twisting to obtain the fine yarn. The total draft ratio of the fine yarn is controlled at 30 times, the twist coefficient of the fine yarn is set at 120, and the spindle speed is controlled at 12000 rpm. Then the fine yarn is wound on the winding machine at a speed of 600 m / min to obtain a smooth initial state blended yarn.

[0085] S4: Place the smooth initial state blended yarn in a wet heat treatment device and treat it in a boiling water bath at 90℃ for 1 minute so that the shrinkage rate of component A reaches 80% of its theoretical boiling water shrinkage rate; after dehydration, immerse it in a softener with a mass concentration of 1g / L, and soak and finish it at a bath ratio of 1:10 and a temperature of 40℃ for 20 minutes. After centrifugal dehydration, dry it loosely in hot air at 80℃ for 10 minutes to obtain a self-crimping high-loft yarn based on high shrinkage difference fiber blend.

[0086] Example 3

[0087] This embodiment provides a self-crimping, high-loft yarn based on a high-shrinkage-difference fiber blend and its preparation method. The preparation method of the self-crimping, high-loft yarn based on a high-shrinkage-difference fiber blend specifically includes the following steps:

[0088] S1: High-shrinkage polypropylene terephthalate staple fiber with boiling water shrinkage rate ≥35%, dry breaking elongation rate 50%, and average cutting length 36mm was prepared by using a smooth spinning oil agent KEOFILSR15 to keep its dynamic friction coefficient within the range of 0.18 to obtain component A. High-modulus modified polyester staple fiber with linear density of 2.0dtex, average cutting length 10% longer than the average cutting length of component A, flexural modulus ≥2.0GPa, and boiling water shrinkage rate ≤5% was prepared by using a cohesive spinning oil agent to keep its dynamic friction coefficient within the range of 0.30 to obtain component B. Fine denier hollow acrylic fiber was selected as component C. The three components of fiber were respectively placed in an environment of 21℃ and 62% relative humidity for 16h to obtain pretreated component A1, pretreated component B2, and pretreated component C3.

[0089] S2: Pretreatment component A1 and pretreatment component C3 are fed into the opening and mixing equipment at a mass ratio of 30:70 for initial opening and mixing, and then carded by a carding machine to obtain premixed A / C sliver; pretreatment component B2 is separately opened and carded, and then drawn and drafted once to produce B sliver; the premixed A / C sliver and B sliver are combined at a mass ratio of 80:20, and then drawn three times, with the draft ratio of the drawing frame controlled at 6.5 times, and then twisted and wound on a roving frame to obtain roving; the roving twist coefficient is controlled at 70;

[0090] S3: The roving is fed into the spinning frame for drafting and twisting to obtain the fine yarn. The total draft ratio of the fine yarn is controlled at 35 times, the twist coefficient of the fine yarn is set at 140, and the spindle speed is controlled at 14000 rpm. Then the fine yarn is wound on the winding machine at a speed of 700 m / min to obtain a smooth initial state blended yarn.

[0091] S4: Place the smooth initial state blended yarn in a wet heat treatment device and treat it in a boiling water bath at 92℃ for 5 minutes to make the shrinkage rate of component A reach 85% of its theoretical boiling water shrinkage rate; after dehydration, immerse it in a softener with a mass concentration of 2g / L, and soak and finish it at a bath ratio of 1:12 and a temperature of 45℃ for 25 minutes. After centrifugal dehydration, dry it loosely in hot air at 85℃ for 12 minutes to obtain a self-crimping high-loft yarn based on high shrinkage difference fiber blend.

[0092] Example 4

[0093] This embodiment provides a self-crimping, high-loft yarn based on a high-shrinkage-difference fiber blend and its preparation method. The preparation method of the self-crimping, high-loft yarn based on a high-shrinkage-difference fiber blend specifically includes the following steps:

[0094] S1: High-shrinkage polypropylene terephthalate staple fiber with boiling water shrinkage ≥35%, dry breaking elongation 60%, and average cutting length 40mm was prepared by using a smooth spinning oil agent POLYFIN501 to bring its dynamic friction coefficient to the range of 0.25 to obtain component A. High-modulus modified polyester staple fiber with linear density of 3.0dtex, average cutting length 20% longer than the average cutting length of component A, flexural modulus ≥2.0GPa, and boiling water shrinkage ≤5% was prepared by using a cohesive spinning oil agent to bring its dynamic friction coefficient to the range of 0.40 to obtain component B. Cashmere was selected as component C. The three components of fiber were respectively placed in an environment of 25℃ and 70% relative humidity for 24h to obtain pretreated component A1, pretreated component B2, and pretreated component C3.

[0095] S2: Pretreatment component A1 and pretreatment component C3 are fed into the opening and cleaning equipment at a mass ratio of 40:60 for initial opening and mixing, and then carded by a carding machine to obtain premixed A / C sliver; pretreatment component B2 is separately opened and carded, and then drawn and drafted twice to produce B sliver; the premixed A / C sliver and B sliver are combined at a mass ratio of 90:30, and then drawn four times, with the draft ratio of the drawing frame controlled at 8 times, and then twisted and wound on a roving frame to obtain roving; the roving twist coefficient is controlled at 90.

[0096] S3: The roving is fed into the spinning frame for drafting and twisting to obtain the fine yarn. The total draft ratio of the fine yarn is controlled at 50 times, the twist coefficient of the fine yarn is set at 180, and the spindle speed is controlled at 18000 rpm. Then the fine yarn is wound on the winding machine at a speed of 1000 m / min to obtain a smooth initial state blended yarn.

[0097] S4: Place the smooth initial state blended yarn in a wet heat treatment device and treat it in a boiling water bath at 100℃ for 15 minutes to make the shrinkage rate of component A reach 100% of its theoretical boiling water shrinkage rate; after dehydration, immerse it in a softener with a mass concentration of 5g / L, and soak and finish it at a bath ratio of 1:20 and a temperature of 60℃ for 40 minutes. After centrifugal dehydration, dry it in hot air at 100℃ for 20 minutes to obtain a self-crimping high-loft yarn based on high shrinkage difference fiber blend.

[0098] Comparative Example 1

[0099] This comparative example provides a self-crimping high-loft yarn based on high-shrinkage fiber blend and its preparation method. The difference from Example 1 is that component B is replaced by polyester short fibers with conventional bending modulus instead of ramie short fibers. Other operating steps and process parameters are exactly the same as in Example 1.

[0100] Comparative Example 2

[0101] This comparative example provides a self-crimping high-loft yarn based on high-shrinkage fiber blend and its preparation method. The difference from Example 1 is that component B is replaced by high-modulus modified polyester staple fiber with a boiling water shrinkage rate of about 18% instead of ramie staple fiber. Other operating steps and process parameters are exactly the same as in Example 1.

[0102] Comparative Example 3

[0103] This comparative example provides a self-crimping high-loft yarn based on high-shrinkage fiber blend and its preparation method. The difference from Example 1 is that no differentiated friction coefficient design is performed, and the same conventional general-purpose spinning oil is applied to the three fibers of component A, component B and component C. Other operating steps and process parameters are exactly the same as in Example 1.

[0104] Comparative Example 4

[0105] This comparative example provides a self-crimping high-loft yarn based on high-shrinkage fiber blend and its preparation method. The difference from Example 1 is that the step-by-step blending strategy is not adopted. The three fibers are mixed and added at one time during the opening stage for opening and mixing. After carding, they directly enter the drawing process. Other operation steps and process parameters are exactly the same as those in Example 1.

[0106] The performance of the self-crimping, high-bulge yarns based on high-shrinkage fiber blends in Examples 1-4 and Comparative Examples 1-4 was tested, and the specific process is as follows:

[0107] The yarns obtained in each embodiment and comparative example were woven into weft-knitted fabric samples with the same structure, and tested after being conditioned to humidity equilibrium for 24 hours under standard atmospheric conditions (20°C, 65%RH).

[0108] Loft test: Take equal weights of yarn and stack them naturally, then measure their loft at 10g / cm³. 2 Specific volume under load (cm) 3 / g).

[0109] Compression resilience test: The fabric sample is held under 50% compression strain for 1 minute and then released. This cycle is repeated 10 times, and the thickness recovery rate is measured after the 10th release.

[0110] Longitudinal morphology observation: The yarn sample after wet heat treatment is placed under a stereomicroscope in a naturally relaxed state. The yarn surface is observed longitudinally at a magnification of 20-50 times. The outer fibers are recorded to see if they are bent and arched and the degree of arching.

[0111] The test results are shown in Table 1.

[0112] Table 1. Performance test results of self-crimping high-loft yarns based on high-shrinkage-difference fiber blends in Examples 1-4 and Comparative Examples 1-4

[0113]

[0114] As shown in Table 1, the test results of Example 1 and Comparative Example 1 indicate that when component B is replaced with polyester staple fiber with conventional bending modulus, under the compressive stress generated by the axial shrinkage of core component A, component B has insufficient bending stiffness and is difficult to form and maintain large-scale bending. Instead, it tends to bend into small, disordered, soft, and curly loops. Therefore, no large-scale curved arched skeleton structure was observed in the longitudinal morphology observation. Due to the lack of a large-scale arched three-dimensional space, the free space inside the yarn is limited, resulting in a decrease in specific volume. The small, soft loop structure has weak bending recovery force and is easily collapsed during repeated compression and is difficult to restore its original shape, thus reducing the thickness recovery rate.

[0115] As shown in Table 1, the test results of Example 1 and Comparative Example 2 indicate that when component B was replaced with high-modulus modified polyester staple fiber with a boiling water shrinkage rate of approximately 18%, component B itself underwent significant axial shrinkage during the wet heat treatment process, tending to shrink synchronously with the core component A. This reduced the tendency for component B to passively buckle and arch under the axial compressive stress generated by the shrinkage of component A. Therefore, component B did not exhibit a bent and arched state in the longitudinal morphology observation, and the yarn as a whole showed a tightly contracted morphology. Since the overall yarn length was shortened due to the joint shrinkage of component B and component A, but the periphery was not stretched, the yarn lacked an effective three-dimensional expansion space, resulting in a decrease in specific volume. The yarn lacked a rigid arch bridge skeleton support inside, and under external compressive load, it lacked a rigid restoring force source to resist deformation and restore its shape, thus reducing the thickness recovery rate.

[0116] As shown in Table 1, the test results of Example 1 and Comparative Example 3 indicate that without differentiated friction coefficient design, applying the same conventional general-purpose spinning oil to all three fibers (component A, component B, and component C) resulted in a convergence of surface friction coefficients among the three fiber components. Component A reduced the preferential driving force for migration towards the yarn core due to its low friction coefficient, while component B also reduced the driving force for being pushed to the outer layer due to its high friction coefficient. Although the step-by-step blending strategy and fiber length difference could still provide some pre-layering and migration drive, the radial gradient distribution was limited. Therefore, only partial bending and arching were observed in the longitudinal morphology, and the distribution was uneven. Since component B was not sufficiently concentrated in the outer layer, its bending and arching skeleton function was limited, and the space for expansion to the outside was insufficient, resulting in a decrease in specific volume. The incomplete skeleton structure caused some areas of the yarn to lack rigid support when subjected to compressive loads, weakening the recovery ability of the fluffy structure and thus reducing the thickness recovery rate.

[0117] As shown in Table 1, the test results of Example 1 and Comparative Example 4 indicate that without a step-by-step blending strategy, the three fibers are mixed and added at once during the opening stage for opening and mixing. After carding, they directly enter the drawing process. Component B may be embedded inside the fiber bundle during carding, losing the initial outer layer position pre-distribution advantage provided by step-by-step blending. Although the differential friction coefficient design and fiber length difference can still provide the driving force for outward migration during subsequent drafting and twisting, due to the randomness of the initial position, some component B fibers have difficulty completing the radial migration from the inside to the outside layer within the drafting stroke. Therefore, the degree of bending and arching in the longitudinal morphology observation is not as good as in Example 1, and the uniformity is insufficient. Due to the reduced concentration of outer layer component B, the three-dimensional space opened by the arched skeleton is reduced, thus the specific volume decreases. The insufficient uniformity of skeleton distribution makes the local support force of the yarn weaker during compression, and the overall compression resistance and elasticity are weakened, thus the thickness recovery rate decreases.

[0118] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A self-crimping, high-bulk yarn based on a high-shrinkage-difference fiber blend, characterized in that: The yarn is composed of a blend of three-component fibers: component A, component B, and component C. Component A is high-shrinkage polypropylene terephthalate short fiber with a boiling water shrinkage rate ≥35%, a dry breaking elongation rate of 20%-60%, and an average cutting length of 35-40 mm. Component B is ramie staple fiber or high-modulus modified polyester staple fiber, with a flexural modulus ≥2.0 GPa, boiling water shrinkage ≤5%, linear density of 1.5-3.0 dtex, and an average cutting length 5%-20% longer than that of component A; Component C is either fine denier hollow acrylic fiber or cashmere. After being subjected to wet heat treatment, the yarn forms a radial gradient distribution structure. Component A is located in the yarn core, component B is located in the outer layer of the yarn and forms a three-dimensional support skeleton structure in a curved and arched state, and component C fills the gaps in the skeleton structure.

2. A method for preparing a self-crimping, high-bulge yarn based on a high-shrinkage-difference fiber blend as described in claim 1, characterized in that, The preparation method includes: S1: Apply a smoothing spinning oil to component A to regulate its dynamic friction coefficient, and apply a cohesive spinning oil to component B to regulate its dynamic friction coefficient; let components A, B and C stand still to obtain pretreated component A (1), pretreated component B (2) and pretreated component C (3). S2: Pretreatment component A (1) and pretreatment component C (3) are put into the opening and mixing equipment and carded to obtain premixed A / C sliver; pretreatment component B (2) is separately opened, carded and drawn to make B sliver; the premixed A / C sliver and B sliver are combined and drawn, and then twisted on a roving frame to obtain roving; S3: The roving is fed into the spinning frame for drafting and twisting to obtain fine yarn, and the fine yarn is wound into the winding bobbin to obtain a smooth initial state blended yarn; S4: The smooth initial state of the blended yarn is treated in a boiling water bath, and after being removed and dehydrated, it is softened and dried to obtain the self-crimping high-loft yarn based on high shrinkage difference fiber blend.

3. The method for preparing a self-crimping, high-loft yarn based on a high-shrinkage-difference fiber blend according to claim 2, characterized in that, In S1, the coefficient of dynamic friction of component A is adjusted to 0.15-0.25, the smoothing spinning oil is selected from any one of POLYFIN501, POLYFIN502 or KEOFILSR15, the coefficient of dynamic friction of component B is adjusted to 0.25-0.40, the cohesive spinning oil is KEOFILSR50, and the components A, B and C are respectively placed in equilibrium at a temperature of 20-25℃, a relative humidity of 60-70% and a time of 12-24h.

4. The method for preparing a self-crimping, high-loft yarn based on a high-shrinkage-difference fiber blend according to claim 2, characterized in that, In S2, the mass ratio of pre-treated component A (1) to pre-treated component C (3) in the premixed A / C raw strip is (20-40):(40-70), and the mass ratio of premixed A / C raw strip to B raw strip is (70-90):(10-30).

5. The method for preparing a self-crimping, high-loft yarn based on a high-shrinkage-difference fiber blend according to claim 2, characterized in that, In S2, pretreatment component B (2) is made into B sliver by drawing 1-2 times; the number of drawing passes for the premixed A / C sliver and B sliver to be combined is 2-4 times, and the draft ratio of the drawing frame during the combining process is 6-8 times; the twist coefficient of the roving is 60-90.

6. The method for preparing a self-crimping, high-bulge yarn based on a high-shrinkage-difference fiber blend according to claim 2, characterized in that, In S3, the total draft ratio of the yarn is 30-50 times, the spindle speed of the spinning machine is 12000-18000 rpm, the twist coefficient of the yarn is 120-180, and the winding speed during the winding process is 600-1000 m / min.

7. The method for preparing a self-crimping, high-bulge yarn based on a high-shrinkage-difference fiber blend according to claim 2, characterized in that, In S4, the temperature of the boiling water bath treatment of the smooth initial state blended yarn is 90-100℃ and the time is 1-15min, so that the actual shrinkage rate of component A reaches 80%-100% of its theoretical boiling water shrinkage rate. The softening finishing is to immerse the dehydrated yarn in a softener solution with a mass concentration of 1-5g / L for 20-40min at a bath ratio of 1:(10-20) and a temperature of 40-60℃. The drying is to dry the yarn by hot air loose drying at 80-100℃ for 10-20min after centrifugal dehydration.

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