Rough twill elastic jean fabric and preparation method thereof

Abstract

The invention discloses a rough twill elastic jean fabric and a preparation method thereof, and belongs to the technical field of textile materials and processing. The rough twill elastic jean fabric is provided with 3 / 1 right twill weave, the warp density is 230-260 pieces / 10 cm, and the weft density is 145-165 pieces / 10 cm; the warp yarns are pure cotton bunchy yarns, and the weft yarns are double-core elastic yarns; wherein slub sections and non-slub sections are periodically distributed on the pure cotton slub yarn in the length direction of the pure cotton slub yarn, the average diameter of the slub sections is D1, the average diameter of the non-slub sections is D2, and D1 / D2 is 1.25-1.45; the length of the bamboo joint section is 4-6 cm, and the length of the non-bamboo joint section is 2-5 cm. The front surface of the rough twill elastic jean fabric is provided with clear and rough right twill lines, and the rough twill elastic jean fabric has excellent elastic elongation and elastic recovery rate and extremely low elastic growth rate.

Description

Technical Field

[0001] This invention belongs to the field of textile materials and processing technology, specifically relating to a rugged twill stretch denim fabric and its preparation method. Background Technology

[0002] Denim is a relatively thick, yarn-dyed twill cotton fabric. The warp yarns are dark, usually indigo, while the weft yarns are light, usually light gray or bleached off-white.

[0003] To balance elasticity and shape retention, conventional stretch denim fabrics typically use uniform yarns and a high warp and weft density in their weaving. This conventional design generally results in a less defined fabric texture, a stiffer feel, and a lack of rugged vintage style. Simultaneously, it often struggles to balance elasticity; while it has a certain elongation rate, its elastic recovery rate is usually less than 80%, and its elastic deformation (permanent deformation) is significant. This causes garments to easily loosen and deform after repeated wear, especially in areas with frequent stress such as the knees and elbows. Repeated wear can lead to sagging, bulging, and even deformation, affecting not only the garment's crispness but also increasing after-sales complaints and product returns. Although some fabrics on the market have attempted to optimize texture or improve elasticity, most focus only on single performance adjustments and fail to systematically address the contradiction between texture definition, elastic elongation, elastic recovery rate, and low permanent deformation. Therefore, how to achieve a distinctive vintage texture, high resilience, and extremely low permanent deformation in a single fabric has become a pressing issue for the industry.

[0004] Patent application CN107237031A discloses a classic rugged, slightly elastic men's denim fabric. The warp yarns are alternately arranged in a 1:7:1:1 ratio of 10-count air-jet spun yarn, 8-count air-jet spun yarn, 10-count slub yarn, and 9-count long random slub yarn. The weft yarns are alternately arranged in a 1:1 ratio of 150 / 40D elastic yarn and 150 / 70D elastic yarn. The air-jet spun yarns are rugged, simple, natural, and clear, fully embodying the essence of denim. The fabric is soft, smooth, and comfortable to wear, and after dyeing, it exhibits vibrant colors and good colorfastness. The warp density is 318.9 ends / 10cm, and the weft density is 248 ends / 10cm. This invention produces a rugged and generous fabric, fully utilizing the characteristics of slub yarn to embody the rugged, simple, and carefree essence of denim. However, this technology cannot simultaneously achieve a distinct retro texture, high resilience, and extremely low permanent deformation (i.e., low elastic elongation). Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a rugged twill stretch denim fabric and its preparation method. The rugged twill stretch denim fabric has a clear and rugged right twill pattern on the front side, and also has excellent elastic elongation, elastic recovery rate and low elastic growth rate.

[0006] To achieve the above objectives, according to one aspect of the present invention, a rugged twill stretch denim fabric is provided, the denim fabric having a 3 / 1 right twill weave, a warp density of 230-260 threads / 10cm, and a weft density of 145-165 threads / 10cm; the warp yarns are pure cotton slub yarns, and the weft yarns are double-core stretch yarns; wherein, the pure cotton slub yarns are periodically distributed with slub segments and non-slub segments along their length direction, the average diameter of the slub segments is D1, the average diameter of the non-slub segments is D2, and the ratio of D1 to D2 is 1.25-1.45; the length of the slub segments is 4-6cm, and the length of the non-slub segments is 2-5cm.

[0007] This invention controls the thickness ratio (D1 / D2=1.25-1.45) and node length period (4-6cm slub nodes, 2-5cm non-slub nodes) of the slub yarn and uses high warp density (230-260 threads / 10cm) weaving to form a regular, three-dimensional, and rugged texture. The high warp density structure effectively constrains the fluffiness of the slub nodes, highlighting the visual texture while avoiding the softness caused by the loose structure, ensuring that the fabric has excellent three-dimensionality and firmness.

[0008] In this invention, the dual-core elastic yarn comprises two parallel spandex core filaments and a cotton yarn outer sheath spirally wrapped around the spandex core filaments; the cotton yarn has a linear density of 6-9 English count and a twist of 40-48 twists / 10cm; the spandex core filaments have a draw ratio of 3.2-3.5 times. This invention constructs a synergistic elastic system by precisely controlling the center-to-center distance of the two spandex core filaments to 0.1-0.3mm and matching it with a 6-9 English count, 40-48 twist / 10cm cotton yarn outer sheath. The dual-core structure achieves a uniform distribution of elasticity within the yarn cross-section, thereby fundamentally overcoming the problems of fabric twisting, curling, and uneven elasticity caused by stress concentration in traditional single-core elastic yarns. The specific center-to-center spacing range prevents the two cores from becoming too close and losing their independent function (<0.1mm), while also avoiding poor coverage and loose structure due to being too far apart (>0.3mm). The specific yarn count and twist of the outer wrapping yarn optimize the overall flexibility and elasticity of the yarn while ensuring a stable wrapping of the two cores and meeting the processing strength requirements.

[0009] In this invention, the twist of the slub segments is 34-38 twists / 10cm, and the twist of the non-slub segments is 44-48 twists / 10cm. The slub segments use a lower twist (34-38 twists / 10cm), resulting in relatively loose fiber cohesion. This makes the yarn fluffier, softer, and easier to expand in diameter, allowing the slub segments to maintain their raised state during weaving and finishing, resulting in a rugged style. The non-slub segments use a higher twist (44-48 twists / 10cm), resulting in tighter fiber cohesion. This makes the yarn stronger, more resilient, and structurally stable, ensuring the overall durability of the fabric. Too low a twist (e.g., below 34 twists) may lead to insufficient strength in the slub segments, making them prone to breakage or pilling; too high a twist (e.g., above 48 twists) will make the non-slub segments too stiff, affecting the overall feel of the fabric. The set range ensures that the slub segments can be significantly raised, while the non-slub segments provide reliable support, together forming a yarn system that balances performance and style.

[0010] In this invention, the fabric has a rugged, three-dimensional surface effect. Within a 100cm x 100cm area, the average height difference between the highest protrusion and the lowest depression is 0.35-0.55mm. If the height difference is less than 0.35mm, the three-dimensional effect will be flat in both visual and tactile senses, failing to achieve a rugged, retro style. If the height difference exceeds 0.55mm, the unevenness is too pronounced, causing the protruding parts (especially the slub sections) of the fabric to wear out more easily during wear, affecting durability.

[0011] According to another aspect of the present invention, a method for preparing the rugged twill stretch denim fabric described in any of the above claims is also provided, comprising the following steps: (1) Spinning: Prepare pure cotton slub yarn as warp yarn and prepare double-core elastic yarn as weft yarn; (2) Weaving: The warp yarns are sequentially subjected to warping, dyeing, warping separation, sizing and threading to form a warp beam; then, on a rapier loom, with a reed number of 55-65 and a reed width of 1760-1780 mm, the warp beam and the weft yarns are used for weaving. (3) Finishing: The woven fabric is successively singed, set, brushed and shrink-proofed; wherein, the brushing process is carried out by a carbon brushing machine, and only the reverse side of the fabric is brushed, the brushing number is 4-6 times, and the brushing speed is 15-20 meters / minute.

[0012] In this invention, in step (1), spinning involves preparing pure cotton slub yarn as warp yarn and preparing double-core elastic yarn as weft yarn. The method for preparing the pure cotton slub yarn includes the following steps: (S1) Raw material pretreatment: Long-staple cotton with an average fiber length of not less than 31mm is used as raw material. After the cleaning and combing process, the short fiber content of the resulting sliver is controlled to be less than 12%. (S2) Spinning: In the spinning process, the middle roller and the back roller are driven by a servo control system to perform a periodic speed change program, alternately forming slub segments and non-slub segments on the yarn body that is output at a uniform speed; wherein, when forming slub segments, the instantaneous speed reduction of the middle and back rollers is 40-50% of the normal speed, and the duration of the speed reduction corresponds to the length of the slub segment formed; when forming non-slub segments, the middle and back rollers maintain normal speed operation, and the operation time corresponds to the length of the non-slub segment formed.

[0013] In this invention, the method for preparing the double-core elastic yarn in step (1) includes the following steps: using a double-hole guide with a center distance of 0.1-0.3 mm, two spandex core yarns are kept at a fixed distance and output in parallel; at a draft ratio of 3.2-3.5, a 6-9 count cotton yarn is used to ring spin and twist the yarn to produce the double-core elastic yarn. In this invention, during the preparation of the double-core elastic yarn, the two spandex core yarns are adjusted by an independent tension control system before entering the double-hole guide, and the real-time tension difference between the two is controlled within ±1.0 cN.

[0014] In this invention, in step (2), weaving involves sequentially performing warp balling, dyeing, warp splitting, sizing, and threading treatments on the warp yarns to create a warp beam. Subsequently, on a rapier loom, with a reed number of 55-65 and a reed width of 1760-1780 mm, the warp beam and the weft yarns are used for weaving. During the weaving process in step (2), the loom speed is 550 rpm, the loom tension is 3600-4000 cN, the back beam height is 10 mm, the shedding time is 310 degrees, the temperature in the weaving workshop is controlled at 26-32℃, and the relative humidity is controlled at 70-75%.

[0015] Furthermore, in step (2), the specific steps of the ball warp are as follows: the yarn is drawn out, the tension of the single yarn is controlled within the range of 25-35cN / yarn by the tension device, and then it is combined into a yarn bundle with a constant number of yarns and evenly wound onto the ball warp beam, with the machine speed controlled at 250-300m / min.

[0016] Further, in step (2), the specific steps of the dyeing process are as follows: the yarn bundle is introduced into a rope dyeing machine and sequentially undergoes scouring, washing, multiple indigo dyeing passes, washing, and post-treatment. The dyeing machine speed is 20-30 m / min; the concentration of scouring alkali (NaOH) is 4-6 g / L; in the indigo dyeing tank, the concentration of indigo powder is 2-4 g / L, and the concentration of sodium hydrosulfite (reducing agent) is 18-22 g / L; the indigo dyeing rate for each dyeing pass is controlled at 1.0%-2.0%, and the total dyeing rate is controlled at 12-18%. In the post-treatment, citric acid (concentration 5-8 g / L) is used for neutralization, and a softener (concentration 40-60 g / L) is applied. The moisture regain of the yarn bundle after dyeing is controlled at 6-9%.

[0017] Furthermore, in step (2), the specific steps of warping are as follows: the yarn bundle is separated into parallel, equidistant single yarns by the warping reed of the warping machine, and then wound onto the warping beam. This process requires controlling the tension of the single yarn at 28-38 cN / yarn and the machine speed at 180-220 m / min.

[0018] Furthermore, in step (2), the specific steps of sizing are as follows: the yarn sheet drawn from the warp beam is immersed in sizing liquid in a sizing tank, then squeezed and dried by a sizing roller, and finally wound into a weaving beam. The sizing speed is 35-45 m / min, the sizing rate is controlled at 8-12%, the yarn moisture regain after drying is 9-11%, and the total elongation is controlled at 0.5-1.5%.

[0019] Furthermore, in step (2), the specific steps of the warp threading are as follows: a 6-page heddle frame is used; the ground weave is 3 / 1 right twill, with 4 ground warp yarns threaded through each reed tooth, and the threading sequence is forward threading (i.e., 1, 2, 3, 4, 5, 6 cycle); the edge weave is 2 / 2 warp-flat, with 20-28 edge yarns used to reinforce each side of the fabric edge.

[0020] In this invention, in step (3), the finishing process involves sequentially singeing, setting, brushing, and shrinkage prevention of the woven fabric. Preferably, the woven fabric is passed through the flame at a speed of 70-90 meters per minute. A "two-front, one-back" fabric-passing method is adopted (i.e., two front singeings and one back singeing), passing through a total of 2-4 flames at a flame temperature of 900-1100℃. The singeed fabric is then introduced into the setting machine at a speed of 40-50 meters per minute and a setting temperature of 180-190℃. During the process, overfeeding is controlled at 1-3%, and the fabric width is stretched to the target range of ±1.5 cm for the finished product width. The brushing process uses a carbon brushing machine, and brushing is only performed on the back side of the fabric. The brushing is performed 4-6 times at a speed of 15-20 meters per minute. The brushed fabric is introduced into the pre-shrinking machine at a speed of 40-50 meters per minute. The steam pressure in the rubber blanket extrusion zone is controlled at 0.25-0.35 MPa, and the steam pressure in the wool blanket drying zone is controlled at 0.45-0.55 MPa.

[0021] Compared with the prior art, the beneficial effects of the present invention are: 1. The denim fabric provided by this invention achieves a significant improvement in appearance and elasticity through the synergistic effect of pure cotton slub yarn with a specific warp shape and double-core elastic yarn in the weft. On the one hand, the periodically distributed coarse and fine structure of the slub yarn directly forms a distinct, natural, and layered three-dimensional rugged texture on the fabric surface, giving the product a unique retro visual style. On the other hand, the double-core elastic yarn uses two parallel spandex core filaments, which can provide more balanced and durable weft recovery force. This not only greatly improves the wearing comfort and freedom of movement of the fabric, but also improves the defects of traditional single-core elastic yarn, such as fabric twisting and curling caused by stress concentration, thereby ensuring excellent elastic elongation, elastic recovery rate, and extremely low elastic growth rate of the finished product. The denim fabric of this invention can prevent the fabric from easily loosening and deforming after being made into clothing, especially solving the problem of loosening, bulging, or even deformation after repeated wear in areas with frequent stress, such as the knees and elbows. The denim trousers made by this invention are designed to withstand long-term wear and vigorous activity without easily deforming at the joints, ensuring the garment's long-term aesthetic appeal. This design has significant practical value and promising market prospects.

[0022] 2. The precise control of the slub shape and double core structure in the spinning process provided by this invention ensures the stability and reproducibility of yarn characteristics from the source; the optimized weaving process configuration ensures the regularity and tightness of the high-density twill structure; and the directional and quantitative reverse brushing finishing process enhances the final three-dimensional rough style without damaging the strength of the fabric. Attached Figure Description

[0023] Figure 1 This is a magnified front view of the denim fabric obtained in Example 1.

[0024] Figure 2 This is a front-view, long-distance photograph of the denim fabric obtained in Example 1.

[0025] Figure 3 This is a magnified photograph of the back of the denim fabric obtained in Example 1.

[0026] Figure 4 This is a long-distance photograph of the back of the denim fabric obtained in Example 1.

[0027] Figure 5 This is a pattern diagram of the denim fabric texture obtained in the example. Detailed Implementation

[0028] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0029] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0030] In this document, when describing embodiments or examples, it should be understood that it is not intended to limit the invention to those embodiments or examples. Rather, all alternatives, modifications, and equivalents of the methods and materials described herein are covered within the scope defined by the claims.

[0031] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0032] This invention provides a rugged twill stretch denim fabric. The denim fabric has a 3 / 1 right-hand twill weave, with a warp density of 230-260 threads / 10cm and a weft density of 145-165 threads / 10cm. The warp yarns are pure cotton slub yarns, and the weft yarns are double-core stretch yarns. The pure cotton slub yarns have slub segments and non-slub segments periodically distributed along their length. The average diameter of the slub segments is D1, and the average diameter of the non-slub segments is D2, with a D1 / D2 ratio of 1.25-1.45. The length of the slub segments is 4-6cm, and the length of the non-slub segments is 2-5cm.

[0033] In some embodiments, the dual-core elastic yarn comprises two parallel spandex core filaments and a cotton yarn outer sheath spirally wrapped around the spandex core filaments; the linear density of the cotton yarn is 6-9 English count and the twist is 40-48 twists / 10cm; the draw ratio of the spandex core filaments is 3.2-3.5 times.

[0034] In some embodiments, the center-to-center distance between the two parallel spandex core filaments in the dual-core elastic yarn is 0.1-0.3 mm.

[0035] In some embodiments, the twist of the bamboo segment is 34-38 twists / 10cm, and the twist of the non-bamboo segment is 44-48 twists / 10cm.

[0036] In some embodiments, the fabric has a rough, three-dimensional surface effect, and the average height difference between the highest protrusion and the lowest depression in a 100cm×100cm area is 0.35-0.55mm.

[0037] This invention also provides a method for preparing the rugged twill stretch denim fabric described in any of the above claims, comprising the following steps: (1) Spinning: Prepare pure cotton slub yarn as warp yarn and prepare double-core elastic yarn as weft yarn; (2) Weaving: The warp yarns are sequentially subjected to warping, dyeing, warping separation, sizing and threading to form a warp beam; then, on a rapier loom, with a reed number of 55-65 and a reed width of 1760-1780 mm, the warp beam and the weft yarns are used for weaving. (3) Finishing: The woven fabric is successively singed, set, brushed and shrink-proofed; wherein, the brushing process is carried out by a carbon brushing machine, and only the reverse side of the fabric is brushed, the brushing number is 4-6 times, and the brushing speed is 15-20 meters / minute.

[0038] In some embodiments, the method for preparing the pure cotton slub yarn in step (1) includes the following steps: (S1) Raw material pretreatment: Long-staple cotton with an average fiber length of not less than 31mm is used as raw material. After the cleaning and combing process, the short fiber content of the resulting sliver is controlled to be less than 12%. (S2) Spinning: In the spinning process, the middle roller and the back roller are driven by a servo control system to perform a periodic speed change program, alternately forming slub segments and non-slub segments on the yarn body that is output at a uniform speed; wherein, when forming slub segments, the instantaneous speed reduction of the middle and back rollers is 40-50% of the normal speed, and the duration of the speed reduction corresponds to the length of the slub segment formed; when forming non-slub segments, the middle and back rollers maintain normal speed operation, and the operation time corresponds to the length of the non-slub segment formed.

[0039] In some embodiments, the method for preparing the double-core elastic yarn in step (1) includes the following steps: using a double-hole guide with a center distance of 0.1-0.3 mm, two spandex core yarns are kept at a fixed distance and output in parallel; at a draft ratio of 3.2-3.5, a 6-9 count cotton yarn is used to ring spin and twist it to produce double-core elastic yarn.

[0040] In some embodiments, during the weaving process in step (2), the loom speed is 550 rpm, the upper tension is 3600-4000 cN, the back beam height is 10 mm, the shedding time is 310 degrees, the temperature in the weaving workshop is controlled at 26-32℃, and the relative humidity is controlled at 70-75%.

[0041] In some embodiments, during the preparation of the dual-core elastic yarn, the two spandex core filaments are adjusted by independent tension control systems before entering the dual-hole guide, and the real-time tension difference between the two is controlled within ±1.0cN.

[0042] The present invention will be described in detail below through embodiments. It should be understood that the following embodiments are only used to further explain and illustrate the content of the present invention by way of example, and are not intended to limit the present invention.

[0043] Example 1 is the best example.

[0044] The chemical additives used in the embodiments and comparative examples of this invention are all commercially available, and the specific information is as follows: Long-staple cotton: purchased from Qingdao Yushengbang Textile Co., Ltd.; Spandex core yarn: 40D spandex yarn, purchased from Jiangsu Qiaoxin Fiber Co., Ltd.; Cotton yarn: purchased from Dongxu Textile Products Co., Ltd.; Indigo: purchased from Shandong Pingju Biotechnology Co., Ltd.; Other auxiliaries and solvents: purchased from Aladdin Reagent Co., Ltd.

[0045] Example 1 This embodiment describes a rugged twill stretch denim fabric. The denim fabric has a 3 / 1 right-hand twill weave, with a warp density of 240 threads / 10cm and a weft density of 150 threads / 10cm. The warp yarn is pure cotton slub yarn, and the weft yarn is double-core stretch yarn. The pure cotton slub yarn has slub segments and non-slub segments periodically distributed along its length. The slub segments are 5cm long, and the non-slub segments are 3.5cm long. The double-core stretch yarn includes two parallel spandex core filaments and a cotton yarn outer layer spirally wrapped around the spandex core filaments. The cotton yarn has a linear density of 7 English count and a twist of 44 twists / 10cm. The slub segments have a twist of 36 twists / 10cm, and the non-slub segments have a twist of 46 twists / 10cm. The preparation method of the rough twill stretch denim fabric includes the following steps: (1) Spinning: Long-staple cotton with an average fiber length of 32mm is selected. After the cleaning and combing process, the short fiber content of the resulting sliver is controlled to be less than 12%. In the spinning process, the middle and back rollers are controlled by a servo system to perform periodic speed changes: during the deceleration phase (45% reduction, lasting for a corresponding time), a 5cm long low-twist (36 twists / 10cm) slub segment is formed; during the normal speed phase, a 3.5cm long high-twist (46 twists / 10cm) non-slub segment is formed. This cycle is repeated to produce 6-count pure cotton slub yarn, which is then wound into warp yarn. On the ring spinning machine, two 40D spandex yarns are fed through independent tensioners, with the tension difference controlled within ±0.8cN. They then pass together through a double-hole guide with a center distance of 0.2mm to ensure parallel output. Under 3.4 times draft, they meet a 7-count cotton yarn in the twisting triangle area and are twisted (44 twists / 10cm) to form a cotton yarn covering a double core elastic yarn. Finally, it is wound into weft yarn. (2) Weaving: The warp yarns are first treated with ball warping, that is, the warp yarns are unwound from the bobbin and drawn out. The tension of the single yarn is controlled at 30 cN / yarn by a tension device. The yarns are combined into bundles of about 330 yarns each and wound evenly onto the ball warp beam at a speed of 280 m / min. Then, dyeing is carried out: the yarn bundles are introduced into a rope dyeing machine and successively undergo scouring (alkali concentration 5 g / L), washing, multi-pass indigo dyeing (dye liquor concentration 3 g / L, sodium hydrosulfite concentration 20 g / L, controlling the single-pass dyeing rate at 1.5% and the total dyeing rate at 16%), washing and post-treatment (neutralization with citric acid 6 g / L and treatment with softener 50 g / L). The dyeing speed is 25 m / min, and the final yarn bundle moisture regain is controlled at 8%. After dyeing, the yarn bundles are separated by a warp splitter and spread into parallel single yarns by a warp splitter. The tension of the single yarn is controlled at 30 cN / yarn and wound onto the warp splitter at a speed of 200 m / min. Next, sizing is performed: the warp yarns on the warp beam are drawn out to form yarn sheets, which are then impregnated in a sizing tank, pressed, dried, and wound into a warp beam. The sizing machine speed is controlled at 40 m / min, the sizing rate at 10%, the moisture regain at 10%, and the total elongation at 1%. Finally, warping is done: a 6-page heald frame is used, with a 3 / 1 right-hand twill weave. The ground warp is threaded in a straight-through pattern (cycles 1, 2, 3, 4, 5, 6) with 4 threads per reed. The selvage uses a 2 / 2 warp-heavy plain weave and is reinforced with 20-28 selvage yarns on each side. The prepared warp beam and weft yarns are woven on a rapier loom, using a reed size of 60 and a reed width of 1770 mm. The loom speed is 550 rpm, the tension is 3800 cN, the back beam height is 10 mm, the sheathing time is 310 degrees, and the ambient temperature in the weaving workshop is controlled at 28℃ and the relative humidity at 72%. (3) Finishing: The woven fabric is passed through the flame burner at a speed of 80 m / min. A two-front-one-back burning method is used (i.e., two front burns and one back burn), passing through a total of 3 flame burners at a flame temperature of 1000℃. The burned fabric is then introduced into the setting machine at a speed of 45 m / min and a setting temperature of 185℃. Overfeeding is controlled at 2% during the process, and the fabric width is stretched to the target range of ±1.5 cm for the finished product width. The napping process uses a carbon napping machine, and only the back side of the fabric is napped. The napping is performed 5 times at a speed of 18 m / min. The napped fabric is then introduced into the pre-shrinking machine at a speed of 45 m / min. The steam pressure in the rubber blanket extrusion zone is controlled at 0.30 MPa, and the steam pressure in the felt drying zone is controlled at 0.50 MPa.

[0046] Example 2 This embodiment describes a rugged twill stretch denim fabric. The denim fabric has a 3 / 1 right-hand twill weave, with a warp density of 230 threads / 10cm and a weft density of 145 threads / 10cm. The warp yarn is pure cotton slub yarn, and the weft yarn is double-core stretch yarn. The pure cotton slub yarn has slub segments and non-slub segments periodically distributed along its length. The slub segments are 4cm long, and the non-slub segments are 2cm long. The double-core stretch yarn includes two parallel spandex core filaments and a cotton yarn outer layer spirally wrapped around the spandex core filaments. The cotton yarn has a linear density of 6 English count and a twist of 40 twists / 10cm. The slub segments have a twist of 34 twists / 10cm, and the non-slub segments have a twist of 44 twists / 10cm. The preparation method of the rough twill stretch denim fabric includes the following steps: (1) Spinning: Long-staple cotton with an average fiber length of 32mm is selected. After the cleaning and combing process, the short fiber content of the resulting sliver is controlled to be less than 12%. In the spinning process, the middle and back rollers are controlled by a servo system to perform periodic speed changes: during the deceleration phase (40% reduction, lasting for a corresponding time), a 4cm long low-twist (34 twists / 10cm) slub segment is formed; during the normal speed phase, a 2cm long high-twist (44 twists / 10cm) non-slub segment is formed. This cycle is repeated to produce 8-count pure cotton slub yarn, which is then wound into warp yarn. On the ring spinning machine, two 40D spandex yarns are fed through independent tensioners, with the tension difference controlled within ±1cN. They then pass together through a double-hole guide with a center distance of 0.1mm to ensure parallel output. Under 3.2 times draft, they meet a 6-count cotton yarn in the twisting triangle area and are twisted (40 twists / 10cm) to form a cotton yarn covering a double-core elastic yarn. Finally, it is wound into weft yarn. (2) Weaving: The warp yarns are first treated with ball warping, that is, the warp yarns are unwound from the bobbin and drawn out. The tension of the single yarn is controlled at 25 cN / yarn by a tension device. They are then combined into a bundle of about 330 yarns each and wound evenly onto the ball warp beam at a speed of 250 m / min. Then, dyeing is carried out: the yarn bundles are introduced into a rope dyeing machine and successively undergo scouring (alkali concentration 4 g / L), washing, multi-pass indigo dyeing (dye liquor concentration 2 g / L, sodium hydrosulfite concentration 18 g / L, controlling the single-pass dyeing rate at 1.0% and the total dyeing rate at 12%), washing and post-treatment (neutralization with citric acid 5 g / L, treatment with softener 40 g / L). The dyeing speed is 20 m / min, and the final yarn bundle moisture regain is controlled at 6%. After dyeing, the yarn bundles are separated by a warp splitter and spread into parallel single yarns by a warp splitter. The tension of the single yarn is controlled at 28 cN / yarn and wound onto the warp splitter at a speed of 180 m / min. Next, sizing is performed: the warp yarns on the warp beam are drawn out to form yarn sheets, which are then impregnated in a sizing tank, pressed, dried, and wound into a warp beam. The sizing machine speed is controlled at 35 m / min, the sizing rate at 8%, the moisture regain at 9%, and the total elongation at 0.5%. Finally, warping is done: a 6-page heald frame is used, with a 3 / 1 right-hand twill weave. The ground warp is threaded in a straight-through pattern (cycles 1, 2, 3, 4, 5, 6) with 4 threads per reed. The selvage uses a 2 / 2 warp-heavy plain weave and is reinforced with 20 selvage yarns on each side. The prepared warp beam and weft yarn cones are woven on a rapier loom, using a reed size of 55, a reed width of 1760 mm, a loom speed of 550 rpm, a tension of 3600 cN, a back beam height of 10 mm, and a shedding time of 310 degrees. The ambient temperature in the weaving workshop is controlled at 26℃ and the relative humidity at 70%. (3) Finishing: The woven fabric is passed through the flame at a speed of 70 m / min. A two-front-one-back passing method is used (i.e., two front singeings and one back singeing), passing through a total of two flames at a flame temperature of 900℃. The singed fabric is then introduced into the setting machine at a speed of 40 m / min and a setting temperature of 180℃. Overfeeding is controlled at 1% during the process, and the fabric width is stretched to the target range of ±1.5 cm for the finished product width. The napping process uses a carbon napping machine, and napping is performed only on the back of the fabric. The napping is performed four times at a speed of 15 m / min. The napped fabric is then introduced into the pre-shrinking machine at a speed of 40 m / min. The steam pressure in the rubber blanket extrusion zone is controlled at 0.25 MPa, and the steam pressure in the felt drying zone is controlled at 0.45 MPa.

[0047] Example 3 This embodiment describes a rugged twill stretch denim fabric. The denim fabric has a 3 / 1 right-hand twill weave, with a warp density of 260 threads / 10cm and a weft density of 165 threads / 10cm. The warp yarns are pure cotton slub yarn, and the weft yarns are double-core stretch yarn. The pure cotton slub yarn has slub segments and non-slub segments periodically distributed along its length. The slub segments are 6cm long, and the non-slub segments are 5cm long. The double-core stretch yarn includes two parallel spandex core filaments and a cotton yarn outer layer spirally wrapped around the spandex core filaments. The cotton yarn has a linear density of 9 English count and a twist of 48 twists / 10cm. The slub segments have a twist of 38 twists / 10cm, and the non-slub segments have a twist of 48 twists / 10cm. The preparation method of the rough twill stretch denim fabric includes the following steps: (1) Spinning: Long-staple cotton with an average fiber length of 32mm is selected. After the cleaning and combing process, the short fiber content of the resulting sliver is controlled to be less than 12%. In the spinning process, the middle and back rollers are controlled by a servo system to perform periodic speed changes: during the deceleration phase (a decrease of 50%, lasting for a corresponding time), a 6cm long low-twist (38 twists / 10cm) slub segment is formed; during the normal speed operation phase, a 5cm long high-twist (48 twists / 10cm) non-slub segment is formed. This cycle is repeated to produce 9-count pure cotton slub yarn, which is then wound into warp yarn. On the ring spinning machine, two 40D spandex yarns are fed through independent tensioners, with the tension difference controlled within ±0.8cN. They then pass together through a double-hole guide with a center distance of 0.3mm to ensure parallel output. Under 3.5 times draft, they meet a 9-count cotton yarn in the twisting triangle area and are twisted (48 twists / 10cm) to form a cotton yarn covering a double core elastic yarn. Finally, it is wound into weft yarn. (2) Weaving: The warp yarns are first balled, that is, the warp yarns are unwound from the bobbin and drawn out. The tension of the single yarn is controlled at 35 cN / yarn by a tension device. They are then combined into a bundle of about 330 yarns each and wound evenly onto the ball warp beam at a speed of 300 m / min. Then, dyeing is carried out: the yarn bundles are introduced into a rope dyeing machine and successively undergo scouring (alkali concentration 6 g / L), washing, multi-pass indigo dyeing (dye liquor concentration 4 g / L, sodium hydrosulfite concentration 22 g / L, controlling the single-pass dyeing rate at 2.0% and the total dyeing rate at 18%), washing and post-treatment (neutralization with citric acid 8 g / L and treatment with softener 60 g / L). The dyeing speed is 30 m / min, and the final yarn bundle moisture regain is controlled at 9%. After dyeing, the yarn bundles are separated by a warp splitter and spread into parallel single yarns by a warp splitter. The tension of the single yarn is controlled at 38 cN / yarn and wound onto the warp splitter at a speed of 220 m / min. Next, sizing is performed: the warp yarns on the warp beam are drawn out to form yarn sheets, which are then impregnated in a sizing tank, pressed, dried, and wound into a warp beam. The sizing machine speed is controlled at 45 m / min, the sizing rate at 12%, the moisture regain at 11%, and the total elongation at 1.5%. Finally, warping is done: a 6-page heald frame is used, with a 3 / 1 right-hand twill weave. The ground warp is threaded in a straight-through pattern (cycles 1, 2, 3, 4, 5, 6) with 4 threads per reed. The selvage uses a 2 / 2 warp-heavy plain weave and is reinforced with 28 selvage yarns on each side. The prepared warp beam and weft yarns are woven on a rapier loom, using a reed size of 65, a reed width of 1780 mm, a loom speed of 550 rpm, a tension of 4000 cN, a back beam height of 10 mm, and a shedding time of 310 degrees. The ambient temperature in the weaving workshop is controlled at 32℃ and the relative humidity at 75%. (3) Finishing: The woven fabric is passed through the flame burner at a speed of 90 m / min. A two-front-one-back burning method is used (i.e., two front burns and one back burn), for a total of 4 flame burns at a flame temperature of 1100℃. The burned fabric is then introduced into the setting machine at a speed of 50 m / min and a setting temperature of 190℃. Overfeeding is controlled at 3% during the process, and the fabric width is stretched to the target range of ±1.5 cm for the finished product width. The napping process uses a carbon napping machine, and napping is performed only on the back side of the fabric. The napping is performed 6 times at a speed of 20 m / min. The napped fabric is then introduced into the pre-shrinking machine at a speed of 50 m / min. The steam pressure in the rubber blanket extrusion zone is controlled at 0.35 MPa, and the steam pressure in the felt drying zone is controlled at 0.55 MPa.

[0048] Comparative Example 1 The rugged twill stretch denim fabric described in this comparative example is exactly the same as that in Example 1, except that when forming the slub segments, the instantaneous speed reduction of the middle and rear rollers is 30% of the normal speed.

[0049] Comparative Example 2 The rough twill stretch denim fabric described in this comparative example is exactly the same as that in Example 1, except that when forming the slub segment, the instantaneous deceleration of the middle and back rollers is 60% of the normal speed.

[0050] Comparative Example 3 The rough twill stretch denim fabric described in this comparative example is exactly the same as that in Example 1, except that the length of the slub segment of the pure cotton slub yarn is set to 8cm, and the length of the non-slub segment is set to 1cm.

[0051] Comparative Example 4 The rough twill stretch denim fabric described in this comparative example is exactly the same as that in Example 1, except that the weft yarn is replaced with a traditional single-core stretch yarn with a single spandex core filament wrapped in cotton yarn.

[0052] Comparative Example 5 The rough twill stretch denim fabric described in this comparative example is exactly the same as that in Example 1, except that the center-to-center distance between the two spandex core yarns in the dual-core stretch yarn is increased to 1.0 mm.

[0053] Performance testing The rough twill stretch denim fabrics obtained in Examples 1-3 and Comparative Examples 1-5 were subjected to performance tests according to the following methods, and the specific results are shown in Table 1.

[0054] (1) Average diameter and diameter ratio of bamboo segment / non-bamboo segment: Using a fiber fineness tester, at least 50 complete bamboo segment cycles were randomly cut and laid flat on a glass slide. Under standard tension (0.5 cN / tex), the yarn diameter was measured at the center position of each bamboo segment and non-bamboo segment. The average values ​​were calculated to obtain D1 and D2, and the ratio of them is the diameter ratio D1 / D2.

[0055] (2) Average height difference of fabric surface: Using a white light interferometer, select at least 5 representative 100cm×100cm areas on the front of the fabric (avoiding the edge of the fabric), scan to obtain the three-dimensional morphology data of the surface, measure the vertical distance difference between the highest protrusion and the lowest depression in the area, and take the average value.

[0056] (3) Fracture strength: Tested according to ASTM D5034.

[0057] (4) Tear strength: Tested according to ASTM D1424.

[0058] (5) Joint slippage: Tested according to ASTM D1683.

[0059] (6) Elastic recovery rate: Tested according to ASTM D3107.

[0060] (7) Elastic elongation: Tested according to ASTM D3107.

[0061] (8) Elastic growth rate: Tested according to ASTM D3107.

[0062] Table 1 Performance data of Examples 1-3 and Comparative Examples 1-5 .

[0063] As shown in Table 1, the embodiments of the present invention achieve a textured fabric surface (average height difference of 0.35-0.55 mm) by controlling the periodic structure of the slub yarn (diameter ratio D1 / D2 between 1.25 and 1.45), creating a distinctive rugged style. In terms of mechanical properties, the fabric has high strength and durability, with good breaking strength, tearing strength, and seam slip resistance in both the radial and weft directions. At the same time, due to the design of the double-core elastic weft yarn, the fabric exhibits excellent elasticity, with an elastic elongation of 16.0%-17.2%, and a high elastic recovery rate (86.5%-89.2%) and a low elastic growth rate (2.2%-2.5%), ensuring good deformation recovery ability and wearing durability.

[0064] A comparison of Example 1 and Comparative Example 1 reveals that the rough texture of the fabric in Comparative Example 1 is significantly reduced. This is mainly because the roller deceleration during the formation of slub segments is smaller, resulting in insufficient increase in the diameter of the slub segments and a weakening of the contrast between thick and thin yarns and the periodic unevenness. In terms of mechanical properties, the radial and weft breaking strengths, tearing strengths, and seam slippage forces of both examples are similar, indicating that the smaller deceleration did not significantly damage the strength of the yarn. However, Comparative Example 1 exhibits a higher elasticity growth rate, indicating that its fabric's dimensional retention ability deteriorates after repeated stretching. This is related to the distribution of internal stress in the fabric caused by changes in its slub structure.

[0065] A comparison of Example 1 and Comparative Example 2 reveals that the average height difference of the fabric surface in Comparative Example 2 is significantly lower than that in Example 1, resulting in a less rugged feel. This is primarily due to the excessive reduction in roller speed during the formation of the slub segments. Although the slub segments are thicker, the excessive thickness disrupts the uniformity and periodicity of the yarn structure, thus weakening the uniform and distinct three-dimensional effect of the fabric surface. In terms of mechanical properties, the weft breaking strength and tearing strength are reduced because the excessively thick areas of the yarn become stress concentration points during weaving and under stress. The recovery rate is also lower, indicating poor internal structural balance. Therefore, the excessively high reduction in speed damages the yarn structure and fabric performance.

[0066] A comparison of Example 1 and Comparative Example 3 reveals that Comparative Example 3 employed a long slub (8cm) + short non-slub (1cm) cycle, resulting in sparse slub distribution and abrupt transitions, disrupting the continuity of the yarn structure. Excessively long slub segments are more prone to structural weaknesses and uneven tension during weaving, thus weakening the overall uniformity and density of the fabric, leading to a decrease in radial breaking strength and tearing strength. Long and loose warp slub segments are more easily pulled out and slip at seams, resulting in reduced seam slip resistance. Simultaneously, due to the increased unevenness of the overall fabric structure caused by warp changes, stability deteriorates, and after repeated stretching, plastic deformation increases, leading to a higher elasticity rate.

[0067] A comparison of Example 1 and Comparative Example 4 reveals that the weft breaking strength and tearing strength of Comparative Example 4 are significantly lower than those of Example 1. This is because the support provided by a single spandex core filament is limited and the stress distribution is more concentrated, making the outer cotton yarn more prone to breakage under stress. Comparative Example 4 shows a significantly lower elastic recovery rate and a significantly higher elastic growth rate, indicating poor deformation recovery and dimensional stability of the fabric after repeated stretching. This is because in a single-core structure, the core filament is prone to deviating from the center during yarn twisting, resulting in uneven coverage, low elasticity efficiency, and a single core filament being more susceptible to plastic deformation within the fabric. Therefore, the dual-core structure used in Example 1, by enhancing the synergistic effect of the core filaments and the stability of the outer sheath, significantly improves strength and elastic durability while maintaining high elasticity.

[0068] A comparison of Example 1 and Comparative Example 5 shows that Comparative Example 5, by increasing the center-to-center distance between the two spandex core filaments to 1.0 mm, prevents the outer cotton yarn from forming a tight and uniform spiral wrap around them, causing the two core filaments to tend to disperse independently within the yarn. This loose structure weakens the overall integrity of the yarn, resulting in lower weft breaking strength and tearing strength compared to Example 1. Comparative Example 5 also shows a significantly reduced elastic recovery rate and an increased elasticity growth rate, indicating poorer fabric recovery after stretching and greater dimensional flexibility. In contrast, the small center-to-center distance used in Example 1 ensures parallel, tight, and uniform wrapping of the two cores, thereby achieving excellent strength retention and high elasticity durability.

[0069] Figure 1 and Figure 2 The denim fabric prepared in Example 1 is shown to have a distinct 3 / 1 right twill weave and a regularly distributed slub effect on the front, showcasing its rugged three-dimensional style achieved through a specific spinning process. Figure 3 and Figure 4 This shows that the twill pattern is still visible on the back of the fabric. Figure 5The image shown is a weave pattern diagram of the denim fabric obtained in the embodiment, which is actually the weave pattern diagram of the ground weave of the fabric of this invention. It can be seen that it is a 3 / 1 right-hand twill fabric. The black squares represent warp yarns on top, and the white squares represent warp yarns on the bottom. This structure gives the fabric surface a clear and full diagonal weave, which not only helps to highlight the rugged style of the slub yarn, but also has good structural stability due to the reasonable distribution of interlacing points.

[0070] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A rugged twill stretch denim fabric, characterized in that, The denim fabric has 3 / 1 right twill weave, warp density of 230-260 per 10 cm, weft density of 145-165 per 10 cm; the warp yarn is pure cotton slub yarn, and the weft yarn is double-core elastic yarn; wherein the pure cotton slub yarn has slub segments and non-slub segments periodically distributed along the length direction of the pure cotton slub yarn, the average diameter of the slub segment is D1, the average diameter of the non-slub segment is D2, and D1 / D2 is 1.25-1.45; the length of the slub segment is 4-6 cm, and the length of the non-slub segment is 2-5 cm.

2. The rugged twill stretch denim fabric of claim 1, wherein, The double-core elastic yarn comprises two parallel spandex core filaments and a cotton yarn outer layer spirally wrapped around the periphery of the spandex core filaments; the linear density of the cotton yarn is 6-9 English, and the twist is 40-48 twists per 10 cm; the draft ratio of the spandex core filament is 3.2-3.5 times.

3. The rugged twill stretch denim fabric of claim 2, wherein, The center distance between the two parallel spandex core filaments in the double-core elastic yarn is 0.1-0.3 mm.

4. The rugged twill stretch denim fabric of claim 1, wherein, The twist of the slub segment is 34-38 twists per 10 cm, and the twist of the non-slub segment is 44-48 twists per 10 cm.

5. The rugged twill stretch denim fabric of claim 1, wherein, The fabric has a rugged three-dimensional fabric surface effect, and the average height difference between the highest protrusion and the lowest depression on the surface within a 100 cm x 100 cm area is 0.35-0.55 mm.

6. The method of making a rugged twill stretch denim fabric according to any one of claims 1-5, characterized in that, The method comprises the following steps: (1) Spinning: prepare pure cotton slub yarn as warp yarn package, and prepare double-core elastic yarn as weft yarn package; (2) Weaving: sequentially perform ball warp, dyeing, warp separation, sizing and threading treatment on the warp yarn package to prepare a weaving beam; then use the weaving beam and the weft yarn package to weave on a rapier loom with a process configuration of reed number 55-65 and reed width 1760-1780 mm; (3) Post-finishing: sequentially perform singeing, setting, sanding and shrink-proofing treatment on the woven gray fabric; wherein the sanding process adopts a carbon sander, and only the reverse side of the fabric is sanded, the sanding frequency is 4-6 times, and the sanding speed is 15-20 m / min.

7. The method of claim 6, wherein the denim stretch fabric is prepared by the steps of: In step (1), the preparation method of the pure cotton slub yarn comprises the following steps: (S1) Raw material pretreatment: long-staple cotton with an average fiber length of not less than 31 mm is used as raw material, and after the carding process, the resulting sliver has a short fiber content of less than 12%; (S2) Spinning: in the spinning process, the servo control system drives the middle roller and the back roller to perform a periodic speed change program, and the slub segments and non-slub segments are alternately formed on the yarn body output at a constant speed; wherein when forming the slub segment, the instantaneous speed reduction amplitude of the middle and back rollers is 40-50% of the normal speed, and the speed reduction duration corresponds to the length of the slub segment; when forming the non-slub segment, the middle and back rollers maintain normal speed operation, and the operation time corresponds to the length of the non-slub segment.

8. The method of claim 6, wherein the denim stretch fabric is prepared by the steps of: In step (1), the preparation method of the double-core elastic yarn comprises the following steps: using a double-hole guide with a center distance of 0.1-0.3 mm to make the two spandex core filaments output in parallel with a fixed distance; under a draft ratio of 3.2-3.5 times, a 6-9 English cotton yarn is used for ring spinning covering and twisting to prepare a double-core elastic yarn.

9. The method of claim 6, wherein the denim stretch fabric is prepared by the steps of: In the weaving process of step (2), the speed of the loom is 550 rpm, the on-loom tension is 3600-4000 cN, the back rest height is 10 mm, the shedding time is 310 degrees, the weaving workshop temperature is controlled at 26-32°C, and the relative humidity is controlled at 70-75%.

10. The method of claim 8, wherein the denim stretch fabric is prepared by the steps of: In the preparation process of the double-core elastic yarn, the two nylon core yarns are respectively adjusted by independent tension control systems before entering the double-hole guide, and the real-time tension difference of the two is controlled within ±1.0 cN.

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