Polyester cotton yarn composite fiber material and preparation method thereof

Abstract

The present application relates to the field of preparation of fiber materials, and particularly relates to a polyester cotton yarn composite fiber material and a preparation method thereof. The present application takes cotton oligosaccharide obtained by mild alkaline hydrolysis and simple filtration of impurities of cotton fibers as a modified component, uniformly mixes the cotton oligosaccharide with polyester chips, and then directly carries out melt blending spinning with cotton fibers. By utilizing the inherent high-temperature environment of melt spinning, a polyester cotton yarn composite fiber material can be prepared through a one-step basic esterification reaction without additional complex catalysts. The present application has simple process and low cost, and also effectively solves the problems of weak interface bonding force, easy delamination, fast mechanical property attenuation and complicated modification process of the existing polyester cotton composite fibers. The prepared composite fibers have excellent mechanical properties, good interface stability and good spinnability, and are suitable for multiple fields such as textiles, clothing, medical textiles and the like.

Description

Technical Field

[0001] This invention relates to the field of fiber material preparation, specifically to a polyester-cotton yarn composite fiber material and its preparation method. Background Technology

[0002] Polyester-cotton composite fibers combine the high strength, wrinkle resistance, and dimensional stability of polyester with the moisture absorption, breathability, and wearing comfort of cotton fibers, making them one of the most widely used composite fiber materials in the textile industry. In existing technologies, polyester-cotton composites are mostly physical blends, where polyester and cotton fibers are physically mixed and spun together. The resulting composite material exhibits only mechanical entanglement without any chemical bonding. The significant polarity difference and poor compatibility between polyester and cellulose lead to obvious defects at the interface between the two phases of the composite fiber. During processing and long-term use, interfacial delamination and separation are highly likely to occur, resulting in a substantial decrease in fiber mechanical properties, reduced abrasion resistance, and severe pilling.

[0003] To address the interfacial compatibility issue, existing technologies often employ methods such as coupling agent modification and grafting modification. For instance, silane and titanate coupling agent modification requires multiple surface treatments of polyester and cotton fibers, respectively. However, this method is cumbersome, and the coupling agent is prone to migration and precipitation, resulting in poor durability of the interfacial modification effect. Cellulose grafting modification requires complex chemical modifications to cellulose to introduce segments compatible with polyester. This involves multiple reaction steps, stringent conditions, and high costs, making it difficult to achieve large-scale industrial production.

[0004] Therefore, inventing a polyester-cotton composite fiber material with improved interfacial bonding, high-performance polyester, simplified process, and controllable cost has great market potential. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a polyester-cotton composite fiber material and its preparation method. This invention uses cotton oligosaccharides obtained from the mild alkaline hydrolysis and simple filtration of cotton fibers as a modifying component. These oligosaccharides are uniformly mixed with polyester chips and then directly melt-blended and spun with the cotton fibers. Utilizing the inherent high-temperature environment of melt spinning, the polyester-cotton composite fiber material can be obtained through a one-step basic esterification reaction without the need for additional complex catalysts. This invention features a simple process and low cost, and effectively solves the problems of weak interfacial bonding, easy delamination, rapid decline in mechanical properties, and cumbersome modification processes in existing polyester-cotton composite fibers. The resulting composite fiber exhibits excellent mechanical properties, good interfacial stability, and good spinnability, making it suitable for multiple fields such as textiles, clothing, and medical textiles.

[0006] This invention discloses a polyester-cotton composite fiber material, which is composed of the following components in parts by weight:

[0007] 60-70 parts polyester chips, 20-30 parts cotton fiber, and 1-6 parts cotton oligosaccharide.

[0008] Preferably, the cotton oligosaccharide is a product obtained by alkaline hydrolysis and filtration to remove impurities from cotton fibers, with a degree of polymerization of 20 to 70.

[0009] Preferably, the cotton fiber is pure carded cotton yarn, combed cotton yarn, or cotton linter, with a fiber length of 40~65mm.

[0010] This invention also discloses a method for preparing a polyester-cotton yarn composite fiber material, the method comprising the following steps: Preparation of S1 cotton oligosaccharide: Cotton fibers are crushed and then subjected to alkaline hydrolysis. After neutralization, filtration to remove impurities, and drying, cotton oligosaccharide is obtained. S2 raw material pretreatment: Vacuum dry polyester chips and cotton fibers, and after drying, mix polyester chips and cotton oligosaccharides evenly to obtain modified polyester blend. S3 Melt Blending Spinning: The modified polyester blend obtained in step S2 and cotton fiber are added to a twin-screw spinning machine in proportion to carry out melt blending spinning, and an esterification reaction occurs to obtain nascent fiber. S4 Post-processing: The nascent fibers obtained in step S3 are subjected to two-stage stretching and heat setting to obtain the polyester-cotton composite fiber material.

[0011] Preferably, in step S1, the particle size of the pulverized cotton fiber is 45-70 mesh; the solvent used for alkaline hydrolysis is a sodium hydroxide aqueous solution with a mass fraction of 3-8%.

[0012] Preferably, in step S1, the solid-liquid ratio of alkaline hydrolysis is 1:(10~20).

[0013] Preferably, in step S2, the vacuum drying temperature of the polyester chips is 120~130℃ and the vacuum drying time is 8~9h; the vacuum drying temperature of the cotton fibers is 70~80℃ and the vacuum drying time is 5~6h.

[0014] Preferably, in step S2, the mixing speed is 900~1200 rpm and the mixing time is 5~10 min.

[0015] Preferably, in step S3, the melting is divided into four zones: zone one has a temperature of 240~250℃, zone two has a temperature of 250~260℃, zone three has a temperature of 260~270℃, and zone four has a temperature of 290~300℃.

[0016] Preferably, in step S4, the first stage of the two-stage stretching is at a temperature of 70~80℃ and a stretching ratio of 2.5~3.5 times; the second stage of stretching is at a temperature of 100~125℃ and a stretching ratio of 1.2~1.7 times; the heat setting temperature is 140~150℃ and the setting time is 10~20s.

[0017] Compared with the prior art, the beneficial effects of the present invention are: This invention provides a polyester-cotton yarn composite fiber material and its preparation method, which has the following characteristics: (1) This invention uses cotton oligosaccharide as a bidirectional link, with one end connected to the polyester molecular chain end by covalent bond, and the other end being a homologous polysaccharide structure with cotton fiber to form a high-density hydrogen bond network, thus constructing a continuous phase interface structure of polyester, cotton oligosaccharide and cotton fiber, effectively eliminating the interface defects between polyester and cellulose, solving the problem of easy delamination and interface peeling in conventional physical blending, and the interface bonding strength of the composite fiber is more than 50% higher than that of conventional polyester-cotton blending, and there is no mechanical property decay after long-term use.

[0018] (2) The cotton oligosaccharides bonded to the ends of the polyester molecular chains are not only highly efficient heterogeneous nucleating agents, which can refine the spherulite size of polyester, improve crystallization uniformity and crystallinity, and improve the dimensional stability of polyester; they can also achieve internal toughening effect through flexible sugar chain structure, solving the problem of increased fiber brittleness caused by conventional nucleating agents. As a result, the high-performance polyester composite fiber obtained has a tensile strength that is 15% higher than that of conventional polyester, a breaking elongation that is 20% higher, a dry heat shrinkage that is more than 30% lower, and significantly improved wrinkle resistance and abrasion resistance.

[0019] (3) The preparation of cotton oligosaccharides only requires mild alkaline hydrolysis of cotton fibers and simple filtration to remove impurities. The process is simple, the raw materials are widely available and the cost is low. In the modification process, the inherent high temperature of melt spinning and the residual catalyst are used to achieve one-step esterification bonding. No additional catalysts, coupling agents and other auxiliaries are required. The production efficiency is high and the overall production cost is low.

[0020] (4) Cotton oligosaccharides are fixed on polyester molecular chains by covalent bonding, which fundamentally avoids the problems of easy agglomeration and poor compatibility with polyester of conventional cellulose modifiers. It achieves nanoscale uniform dispersion in polyester matrix without phase separation. There are no broken or fuzzy fibers in the composite fiber spinning process. The spinning stability is good, the yield is high, and the performance difference between batches is small.

[0021] (5) The composite fiber obtained by the present invention has the high performance of polyester and the comfort and breathability of cotton fiber. It has good biocompatibility and can be used not only for regular clothing and home textile fabrics, but also for close-fitting textiles, medical textiles, industrial textiles and other fields. Detailed Implementation

[0022] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0023] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0024] Example 1: A polyester-cotton composite fiber material, composed of the following components in parts by weight: The composition consists of 60 parts polyester chips, 20 parts cotton fiber, and 1 part cotton oligosaccharide. The cotton oligosaccharide is a product obtained by alkaline hydrolysis and filtration to remove impurities from cotton fiber, with a degree of polymerization of 70. The cotton fiber is pure carded cotton yarn with a fiber length of 65 mm.

[0025] A method for preparing a polyester-cotton composite fiber material includes the following steps: Preparation of S1 cotton oligosaccharide: Cotton fibers were crushed to 70 mesh and added to a 3% sodium hydroxide aqueous solution with a solid-liquid ratio of 1:10. The mixture was stirred and hydrolyzed at 40°C for 2 hours. The pH of the system was adjusted to 6.5 using dilute hydrochloric acid for neutralization. The mixture was filtered through a 100-mesh filter cloth to remove unhydrolyzed residues and small molecule impurities, thus obtaining cotton oligosaccharide.

[0026] S2 raw material pretreatment: Polyester chips and cotton fibers are vacuum dried. The vacuum drying temperature of polyester chips is 120℃ and the vacuum drying time is 8h; the vacuum drying temperature of cotton fibers is 70℃ and the vacuum drying time is 5h. After drying, polyester chips and cotton oligosaccharides are mixed evenly. The mixing speed is 900rpm and the mixing time is 5min to obtain modified polyester mixture.

[0027] S3 Melt Blending Spinning: The modified polyester blend obtained in step S2 and cotton fiber are added to a twin-screw spinning machine in proportion to carry out melt blending spinning and esterification reaction. The melt is divided into four zones: zone 1 temperature is 240℃, zone 2 temperature is 250℃, zone 3 temperature is 260℃, and zone 4 temperature is 290℃, to obtain nascent fiber.

[0028] S4 Post-processing: The nascent fibers obtained in step S3 are subjected to two-stage stretching and heat setting treatment. The first stage stretching temperature is 70℃ and the stretching ratio is 2.5 times. The second stage stretching temperature is 100℃ and the stretching ratio is 1.2 times. The heat setting temperature is 140℃ and the setting time is 10s to obtain the polyester-cotton composite fiber material.

[0029] Example 2: A polyester-cotton composite fiber material, composed of the following components in parts by weight: The composition consisted of 62 parts polyester chips, 22 parts cotton fibers, and 2 parts cotton oligosaccharides. The cotton oligosaccharides were obtained by alkaline hydrolysis and filtration to remove impurities from the cotton fibers, with a degree of polymerization of 60. The cotton fibers were combed cotton yarn with a fiber length of 60 mm.

[0030] A method for preparing a polyester-cotton composite fiber material includes the following steps: Preparation of S1 cotton oligosaccharide: Cotton fibers were crushed to 65 mesh and added to a 4% sodium hydroxide aqueous solution with a solid-liquid ratio of 1:12. The mixture was stirred and hydrolyzed at 42℃ for 2.2 h. The pH of the system was adjusted to 6.7 by dilute hydrochloric acid for neutralization. The mixture was filtered through a 100-mesh filter cloth to remove unhydrolyzed residues and small molecule impurities, thus obtaining cotton oligosaccharide.

[0031] S2 raw material pretreatment: Polyester chips and cotton fibers were vacuum dried. The vacuum drying temperature of polyester chips was 122℃ and the vacuum drying time was 8.2h. The vacuum drying temperature of cotton fibers was 72℃ and the vacuum drying time was 5.2h. After drying, polyester chips and cotton oligosaccharides were mixed evenly. The mixing speed was 950rpm and the mixing time was 6min to obtain modified polyester mixture.

[0032] S3 Melt Blending Spinning: The modified polyester blend obtained in step S2 and cotton fiber are added to a twin-screw spinning machine in proportion to carry out melt blending spinning and esterification reaction. The melt is divided into four zones: zone 1 temperature is 242℃, zone 2 temperature is 252℃, zone 3 temperature is 262℃, and zone 4 temperature is 292℃, to obtain nascent fiber.

[0033] S4 Post-processing: The nascent fibers obtained in step S3 are subjected to two-stage stretching and heat setting treatment. The first stage stretching temperature is 72℃ and the stretching ratio is 2.7 times. The second stage stretching temperature is 105℃ and the stretching ratio is 1.3 times. The heat setting temperature is 142℃ and the setting time is 14s to obtain the polyester-cotton composite fiber material.

[0034] Example 3: A polyester-cotton composite fiber material, composed of the following components in parts by weight: The composition consisted of 64 parts polyester chips, 24 parts cotton fibers, and 3 parts cotton oligosaccharides. The cotton oligosaccharides were obtained by alkaline hydrolysis and filtration to remove impurities from the cotton fibers, with a degree of polymerization of 50. The cotton fibers were short cotton linters with a fiber length of 55 mm.

[0035] A method for preparing a polyester-cotton composite fiber material includes the following steps: Preparation of S1 cotton oligosaccharide: Cotton fibers were crushed to 60 mesh and added to a 5% sodium hydroxide aqueous solution with a solid-liquid ratio of 1:14. The mixture was stirred and hydrolyzed at 44℃ for 2-3 hours. The pH of the system was adjusted to 6.9 using dilute hydrochloric acid for neutralization. The mixture was filtered through a 100-mesh filter cloth to remove unhydrolyzed residues and small molecule impurities, thus obtaining cotton oligosaccharide.

[0036] S2 raw material pretreatment: Polyester chips and cotton fibers were vacuum dried. The vacuum drying temperature of polyester chips was 124℃ and the vacuum drying time was 8.4h. The vacuum drying temperature of cotton fibers was 74℃ and the vacuum drying time was 5.4h. After drying, polyester chips and cotton oligosaccharides were mixed evenly. The mixing speed was 1000rpm and the mixing time was 7min to obtain modified polyester mixture.

[0037] S3 Melt Blending Spinning: The modified polyester blend obtained in step S2 and cotton fiber are added to a twin-screw spinning machine in proportion to carry out melt blending spinning and esterification reaction. The melt is divided into four zones: zone 1 temperature is 244℃, zone 2 temperature is 254℃, zone 3 temperature is 264℃, and zone 4 temperature is 294℃, to obtain nascent fiber.

[0038] S4 Post-processing: The nascent fibers obtained in step S3 are subjected to two-stage stretching and heat setting treatment. The first stage stretching temperature is 74℃ and the stretching ratio is 2.9 times. The second stage stretching temperature is 110℃ and the stretching ratio is 1.4 times. The heat setting temperature is 144℃ and the setting time is 14s to obtain the polyester-cotton composite fiber material.

[0039] Example 4: A polyester-cotton composite fiber material, composed of the following components in parts by weight: The composition consisted of 66 parts polyester chips, 26 parts cotton fiber, and 4 parts cotton oligosaccharide. The cotton oligosaccharide was obtained by alkaline hydrolysis and filtration to remove impurities from the cotton fiber, with a degree of polymerization of 40. The cotton fiber was pure carded cotton yarn with a fiber length of 50 mm.

[0040] A method for preparing a polyester-cotton composite fiber material includes the following steps: Preparation of S1 cotton oligosaccharide: Cotton fibers were crushed to 55 mesh and added to a 6% sodium hydroxide aqueous solution with a solid-liquid ratio of 1:16. The mixture was stirred and hydrolyzed at 46℃ for 2.6 h. The pH of the system was adjusted to 7.1 by dilute hydrochloric acid for neutralization. The mixture was filtered through a 100-mesh filter cloth to remove unhydrolyzed residues and small molecule impurities, thus obtaining cotton oligosaccharide.

[0041] S2 raw material pretreatment: Polyester chips and cotton fibers were vacuum dried. The vacuum drying temperature of polyester chips was 126℃ and the vacuum drying time was 8.6h. The vacuum drying temperature of cotton fibers was 76℃ and the vacuum drying time was 5.6h. After drying, polyester chips and cotton oligosaccharides were mixed evenly. The mixing speed was 1050rpm and the mixing time was 8min to obtain modified polyester mixture.

[0042] S3 Melt Blending Spinning: The modified polyester blend obtained in step S2 and cotton fiber are added to a twin-screw spinning machine in proportion to carry out melt blending spinning and esterification reaction. The melt is divided into four zones: zone 1 temperature is 246℃, zone 2 temperature is 256℃, zone 3 temperature is 266℃, and zone 4 temperature is 296℃, to obtain nascent fiber.

[0043] S4 Post-processing: The nascent fibers obtained in step S3 are subjected to two-stage stretching and heat setting treatment. The first stage stretching temperature is 76℃ and the stretching ratio is 3.1 times. The second stage stretching temperature is 115℃ and the stretching ratio is 1.5 times. The heat setting temperature is 146℃ and the setting time is 16s to obtain the polyester-cotton composite fiber material.

[0044] Example 5: A polyester-cotton composite fiber material, composed of the following components in parts by weight: The composition consisted of 68 parts polyester chips, 28 parts cotton fibers, and 5 parts cotton oligosaccharides. The cotton oligosaccharides were obtained by alkaline hydrolysis and filtration to remove impurities from the cotton fibers, with a degree of polymerization of 30. The cotton fibers were pure carded cotton yarn with a fiber length of 45 mm.

[0045] A method for preparing a polyester-cotton composite fiber material includes the following steps: Preparation of S1 cotton oligosaccharide: Cotton fibers were crushed to 50 mesh and added to a 7% sodium hydroxide aqueous solution with a solid-liquid ratio of 1:18. The mixture was stirred and hydrolyzed at 48°C for 2.8 hours. The pH of the system was adjusted to 7.3 using dilute hydrochloric acid for neutralization. The mixture was filtered through a 100-mesh filter cloth to remove unhydrolyzed residues and small molecule impurities, thus obtaining cotton oligosaccharide.

[0046] S2 raw material pretreatment: Polyester chips and cotton fibers were vacuum dried. The vacuum drying temperature of polyester chips was 128℃ and the vacuum drying time was 8.8h. The vacuum drying temperature of cotton fibers was 78℃ and the vacuum drying time was 5.8h. After drying, polyester chips and cotton oligosaccharides were mixed evenly. The mixing speed was 1100rpm and the mixing time was 9min to obtain modified polyester mixture.

[0047] S3 Melt Blending Spinning: The modified polyester blend obtained in step S2 and cotton fiber are added to a twin-screw spinning machine in proportion to carry out melt blending spinning and esterification reaction. The melt is divided into four zones: zone 1 temperature is 248℃, zone 2 temperature is 258℃, zone 3 temperature is 268℃, and zone 4 temperature is 298℃, to obtain nascent fiber.

[0048] S4 Post-processing: The nascent fibers obtained in step S3 are subjected to two-stage stretching and heat setting treatment. The first stage stretching temperature is 78℃ and the stretching ratio is 3.3 times. The second stage stretching temperature is 8120℃ and the stretching ratio is 1.6 times. The heat setting temperature is 148℃ and the setting time is 18s to obtain the polyester-cotton composite fiber material.

[0049] Example 6: A polyester-cotton composite fiber material, composed of the following components in parts by weight: The composition consists of 70 parts polyester chips, 30 parts cotton fiber, and 6 parts cotton oligosaccharide. The cotton oligosaccharide is a product obtained by alkaline hydrolysis and filtration to remove impurities from cotton fiber, with a degree of polymerization of 70. The cotton fiber is pure carded cotton yarn with a fiber length of 65 mm.

[0050] A method for preparing a polyester-cotton composite fiber material includes the following steps: Preparation of S1 cotton oligosaccharide: Cotton fibers were crushed to 70 mesh and added to an 8% sodium hydroxide aqueous solution with a solid-liquid ratio of 1:20. The mixture was stirred and hydrolyzed at 50°C for 3 hours. The pH of the system was adjusted to 7.5 using dilute hydrochloric acid for neutralization. The mixture was filtered through a 100-mesh filter cloth to remove unhydrolyzed residues and small molecule impurities, thus obtaining cotton oligosaccharide.

[0051] S2 raw material pretreatment: Polyester chips and cotton fibers are vacuum dried. The vacuum drying temperature of polyester chips is 130℃ and the vacuum drying time is 9h; the vacuum drying temperature of cotton fibers is 80℃ and the vacuum drying time is 6h. After drying, polyester chips and cotton oligosaccharides are mixed evenly. The mixing speed is 1200rpm and the mixing time is 10min to obtain modified polyester mixture.

[0052] S3 Melt Blending Spinning: The modified polyester blend obtained in step S2 and cotton fiber are added to a twin-screw spinning machine in proportion to carry out melt blending spinning and esterification reaction. The melt is divided into four zones: zone 1 temperature is 250℃, zone 2 temperature is 260℃, zone 3 temperature is 270℃, and zone 4 temperature is 300℃, to obtain nascent fiber.

[0053] S4 Post-processing: The nascent fibers obtained in step S3 are subjected to two-stage stretching and heat setting treatment. The first stage stretching temperature is 80℃ and the stretching ratio is 3.5 times. The second stage stretching temperature is 125℃ and the stretching ratio is 1.7 times. The heat setting temperature is 150℃ and the setting time is 20s to obtain the polyester-cotton composite fiber material.

[0054] Example 7: No cotton oligosaccharides were added to the raw materials, and no cotton oligosaccharide preparation was carried out in the preparation process. All other raw materials and step parameters were the same as in Example 5.

[0055] Example 8: Conventional preparation method of polyester-cotton composite fiber material: Dried polyester chips and cotton cellulose powder were added to a mixer according to the target ratio, and then 3% silane coupling agent was added and mixed at 1000 rpm for 10 min to obtain a uniform physical blend material; the blend material was added to a twin-screw spinning mill for melt spinning, with the temperature of each zone of the screw set to 250℃, the die head temperature to 270℃, the screw speed to 600 rpm, and the spinning speed to 900 m / min to obtain nascent fibers; the nascent fibers were stretched and heat-set to obtain polyester-cotton composite fiber material.

[0056] The properties of the polyester-cotton composite fiber materials prepared in Examples 1-8 were tested, and the test results are shown in the table below:

[0057] The data in the table above shows that: (1) When the amount of cotton oligosaccharide added is increased from 1 part to 5 parts, the functional groups that can be bonded to the ends of the polyester molecular chains increase simultaneously, the number of bidirectional bonding sites increases, and the interfacial bonding strength continues to improve. At the same time, the content of cotton oligosaccharide as a heterogeneous nucleating agent increases, which can refine polyester spherulites more efficiently and improve crystallization uniformity. Therefore, tensile strength, elongation at break, and dimensional stability are improved simultaneously, reaching the optimal value at an addition amount of 5 parts. When the amount of cotton oligosaccharide is increased to 6 parts, the reactive sites at the ends of the polyester molecular chains tend to be saturated. Excessive cotton oligosaccharide cannot completely achieve covalent bonding, and a small amount of free cotton oligosaccharide will slightly affect the crystallization continuity of the polyester matrix. Therefore, the various properties are lower than those in Example 5, but are still significantly better than those in other Examples 7-8.

[0058] (2) The interfacial peel strength of Example 5 reached 13.5 N / 25 mm, while that of Example 7 was only 7.2 N / 25 mm. The strength retention rate of Example 5 after 50 washes was 97.5%, which was 15.6% higher than that of Example 7 and 10.4% higher than that of Example 8. Example 7 was only a physical blend of polyester and cotton fibers. Due to the large difference in polarity between the two, without any chemical bonding force, it relied solely on mechanical winding, resulting in a large number of interfacial defects. It was prone to interfacial peeling and fiber slippage, thus the interfacial strength was low and the mechanical properties were significantly reduced after washing. Example 8 was a conventional coupling agent modification, which only physically coated the cotton fibers with silane coupling agents. The bonding force was weak and it was easily washed away, thus the durability was poor. Examples 1-6 are polyester-cotton composite fiber materials prepared by the present invention. The present invention constructs a continuous phase interface structure of polyester, cotton oligosaccharide and cotton fiber through cotton oligosaccharide. Under the dual action of covalent bonding and hydrogen bonding, the interface defects are effectively eliminated, and the polyester-cotton composite fiber material fundamentally solves the problems of easy delamination and interface peeling.

[0059] (3) The breaking strength of Example 5 was 4.95 cN / dtex, which was 1.15 higher than that of the blank control Example 7; the breaking elongation of Example 5 was 41.2%, which was 22 higher than that of Example 7; and the dry heat shrinkage rate of Example 7 at 180℃ was only 1.7%, which was 2.1 lower than that of Example 7. This is because the cotton oligosaccharide bonded to the ends of the polyester molecular chain, on the one hand, acts as a highly efficient heterogeneous nucleating agent, which greatly refines the spherulite size of polyester, improves the uniformity and crystallinity of crystallization, thereby improving the tensile strength and dimensional stability of the fiber and reducing the heat shrinkage rate; on the other hand, the flexible sugar chain structure of cotton oligosaccharide can form an internal toughening effect in the polyester matrix, effectively alleviating the problem of increased fiber brittleness caused by increased crystallinity, and achieving a comprehensive improvement in strength and toughness.

[0060] (4) The anti-pilling grade of Example 5 reached the highest level of 5.0, which is 2 levels higher than that of Example 7 and 1.5 levels higher than that of Example 8. This is because in conventional polyester-cotton blended fibers, the interfacial bonding force between polyester and cotton fibers is weak, and the fibers are easy to slip off the yarn to form fuzz, which in turn causes pilling due to friction. However, the present invention firmly binds polyester and cotton fibers through the bidirectional bonding effect of cotton oligosaccharides, making the fibers less likely to slip off and reducing fuzz. Therefore, the anti-pilling performance and abrasion resistance are significantly improved, while retaining the breathability of cotton fibers and the high performance of polyester, making it suitable for various applications such as clothing, home textiles, and medical textiles.

[0061] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A polyester-cotton composite fiber material, characterized in that, Composed of the following components by weight: 60-70 parts polyester chips, 20-30 parts cotton fiber, and 1-6 parts cotton oligosaccharide.

2. The polyester-cotton composite fiber material according to claim 1, characterized in that, The cotton oligosaccharide is a product obtained by alkaline hydrolysis and filtration to remove impurities from cotton fibers, with a degree of polymerization of 20-70.

3. The polyester-cotton composite fiber material according to claim 1, characterized in that, The cotton fiber is pure cotton carded yarn, combed cotton yarn, or cotton linters, with a fiber length of 40~65mm.

4. A method for preparing a polyester-cotton composite fiber material, characterized in that, Includes the following steps: Preparation of S1 cotton oligosaccharide: Cotton fibers are crushed and then subjected to alkaline hydrolysis. After neutralization, filtration to remove impurities, and drying, cotton oligosaccharide is obtained. S2 raw material pretreatment: Vacuum dry polyester chips and cotton fibers, and after drying, mix polyester chips and cotton oligosaccharides evenly to obtain modified polyester blend. S3 Melt Blending Spinning: The modified polyester blend obtained in step S2 and cotton fiber are added to a twin-screw spinning machine in proportion to carry out melt blending spinning, and an esterification reaction occurs to obtain nascent fiber. S4 Post-processing: The nascent fibers obtained in step S3 are subjected to two-stage stretching and heat setting to obtain the polyester-cotton composite fiber material.

5. The method for preparing a polyester-cotton composite fiber material according to claim 4, characterized in that, In step S1, the particle size of the pulverized cotton fiber is 45-70 mesh; the solvent used for alkaline hydrolysis is a sodium hydroxide aqueous solution with a mass fraction of 3-8%.

6. The method for preparing a polyester-cotton composite fiber material according to claim 4, characterized in that, In step S1, the solid-liquid ratio of alkaline hydrolysis is 1:(10~20).

7. The method for preparing a polyester-cotton composite fiber material according to claim 4, characterized in that, In step S2, the vacuum drying temperature of the polyester chips is 120~130℃ and the vacuum drying time is 8~9h; the vacuum drying temperature of the cotton fibers is 70~80℃ and the vacuum drying time is 5~6h.

8. The method for preparing a polyester-cotton composite fiber material according to claim 4, characterized in that, In step S2, the mixing speed is 900~1200 rpm, and the mixing time is 5~10 min.

9. The method for preparing a polyester-cotton composite fiber material according to claim 4, characterized in that, In step S3, the melting process is divided into four zones: zone one has a temperature of 240-250°C, zone two has a temperature of 250-260°C, zone three has a temperature of 260-270°C, and zone four has a temperature of 290-300°C.

10. The method for preparing a polyester-cotton composite fiber material according to claim 4, characterized in that, In step S4, the first stage of the two-stage stretching is at a temperature of 70~80℃ and a stretching ratio of 2.5~3.5 times; the second stage of stretching is at a temperature of 100~125℃ and a stretching ratio of 1.2~1.7 times; the heat setting temperature is 140~150℃ and the setting time is 10~20s.

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