Preparation method of high-modulus regenerated viscose fiber composite fabric

Abstract

The invention discloses a preparation method of a high-modulus regenerated viscose fiber composite fabric, which comprises the following steps: S1, selecting regenerated viscose staple fibers, soaking the regenerated viscose staple fibers in deionized water, drying and carding to obtain uniformly dispersed regenerated viscose fibers; s2, dipping the uniformly dispersed regenerated viscose fibers in the cellulose nanocrystal aqueous dispersion liquid, taking out the regenerated viscose fibers, and pre-drying the regenerated viscose fibers; s3, respectively and sequentially dipping the regenerated viscose fibers into the solution to form a coating, and then dehydrating, drying and curing to obtain modified regenerated viscose fibers; s4, mixing the modified regenerated viscose fibers with high-modulus polyester staple fibers, preparing blended yarns after cotton blending, and weaving to obtain a primary composite fabric; s5, performing hot rolling compounding, shaping treatment, washing and drying on the primary composite fabric to obtain the high-modulus regenerated viscose fiber composite fabric. The preparation method disclosed by the invention has the advantages that the problems of low fabric modulus, poor interface bonding, unstable performance and the like can be solved, and the preparation method is environment-friendly and practical.

Description

Technical Field

[0001] This invention relates to the field of textile materials technology, and in particular to a method for preparing a high-modulus recycled viscose fiber composite fabric. Background Technology

[0002] Regenerated viscose fiber is an environmentally friendly regenerated fiber made from natural cellulose (such as wood pulp and cotton linters) through chemical dissolution and respinning. It combines the moisture absorption, softness, and biodegradability of natural fibers and is widely used in the textile industry, currently accounting for more than 80% of the regenerated cellulose fiber market. However, traditional regenerated viscose fiber has inherent defects such as low crystallinity (35-55%) and insufficient molecular chain orientation, resulting in fabrics with low breaking modulus, poor tensile deformation resistance, and a wet modulus that is less than 50% of the dry modulus. Furthermore, it is prone to wrinkling and deformation after long-term use or washing, which seriously limits its application in high-end textile fields.

[0003] To improve the modulus of recycled viscose fiber fabrics, existing technologies mainly employ two improvement approaches: one is to perform single modification treatment on the recycled viscose fiber, such as surface modification with silane coupling agents or nanoparticle filling. However, single modification is difficult to achieve a significant increase in modulus and can easily lead to a stiffer fiber feel and reduced breathability. The other approach is to simply blend and composite recycled viscose fiber with high-modulus fiber. However, due to the large difference in surface polarity between the two fibers, the interfacial bonding is weak, resulting in limited modulus improvement in the composite fabric. Furthermore, defects such as delamination, pilling, and fuzzing are prone to occur. At the same time, the price of lyocell fiber is 1.5 times that of recycled viscose fiber, significantly increasing production costs. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing high-modulus recycled viscose fiber composite fabric. The preparation process is simple and cost-controllable, which can effectively solve the problems of low modulus, poor interfacial bonding, and unstable performance of recycled viscose fiber composite fabric, while taking into account both environmental protection and practicality.

[0005] The above-mentioned technical objective of the present invention is achieved through the following technical solution:

[0006] A method for preparing a high-modulus recycled viscose fiber composite fabric includes the following steps: S1. Select recycled viscose short fibers, soak them in deionized water, and then dry them in an oven until the fiber moisture content drops to 8-10%. After combing, uniformly dispersed recycled viscose fibers are obtained. S2, the uniformly dispersed regenerated viscose fiber is immersed in an aqueous dispersion of cellulose nanocrystals, treated under ultrasonic assistance, and then pre-dried after removal; S3 involves sequentially immersing the recycled viscose fibers treated in S2 into an aqueous polyurethane prepolymer and a solution containing a chain extender and a silane coupling agent, respectively, to carry out an in-situ interfacial polymerization reaction. After forming a coating, the fibers are dehydrated, dried, and cured to obtain modified recycled viscose fibers. S4, modified recycled viscose fiber is mixed with high modulus polyester staple fiber, and after blending, it is successively processed through carding, drawing, roving and spinning to prepare blended yarn, which is then woven using an air-jet loom to obtain the initial composite fabric. S5, after the initial composite fabric is hot-rolled, shaped and washed and dried, a high-modulus recycled viscose fiber composite fabric is obtained.

[0007] Preferably, in step S1, the fineness of the recycled viscose short fibers is 1.2~1.5 dtex and the length is 38~42 mm. The soaking temperature of the deionized water is 25~30℃ and the soaking time is 20~30 min. The drying temperature of the oven is 80~85℃ and the drying time is 2~3 h.

[0008] Preferably, the preparation method of the aqueous dispersion of cellulose nanocrystals in step S2 is as follows: microcrystalline cellulose is added to a sulfuric acid solution with a concentration of 60~65wt%, acidified at 45~50℃ for 60~90min, and then centrifuged and dialyzed until neutral to obtain an aqueous dispersion of cellulose nanocrystals with a mass fraction of 1~3wt%, wherein the bath ratio of the regenerated viscose short fibers to the aqueous dispersion of medium cellulose nanocrystals is 1:20~1:30.

[0009] Preferably, in step S2, the ultrasonic treatment power is 250~350W, the time is 20~40min, the pre-drying temperature is 80℃, and the pre-drying time is 5~7min.

[0010] Preferably, in step S3, the solid content of the waterborne polyurethane prepolymer is 40%, and the recycled viscose fiber is impregnated in the waterborne polyurethane prepolymer, subjected to two dips and two nips, with a nip-out rate of 80%.

[0011] Preferably, in step S3, the solution containing the chain extender and silane coupling agent is an aqueous solution containing 1 wt% ethylenediamine and 0.5 wt% KH-550, and the regenerated viscose fiber is impregnated in the solution containing the chain extender and silane coupling agent and reacted at 50°C for 10-15 min.

[0012] Preferably, in step S3, the dehydration speed is 2000~2500 r / min, the dehydration time is 5~8 min, and the specific steps of drying and curing are as follows: first, pre-dry at 90~95℃ for 30~40 min, then raise the temperature to 110~120℃ and keep it warm for 2~2.5 h.

[0013] Preferably, in step S4, the mass ratio of modified recycled viscose fiber to high-modulus polyester staple fiber is 70:30. The high-modulus polyester staple fiber has a fineness of 1.0~1.2 dtex, a length of 35~38 mm, a breaking strength ≥5.5 cN / dtex, a blending speed of 10~15 m / min, a blending time of 15~20 min, a carding speed of 25~30 m / min, a drawing speed of 80~100 m / min, a roving twist of 35~40 twists / 10 cm, a yarn twist of 80~90 twists / 10 cm, a weaving speed of 300~350 r / min, a warp density of 380~420 threads / 10 cm, and a weft density of 280~320 threads / 10 cm.

[0014] Preferably, in step S5, the hot rolling temperature for hot rolling composite is 125~135℃, the hot rolling pressure is 0.3~0.4MPa, the hot rolling speed is 6~7m / min, the sizing temperature is 130~140℃, the sizing time is 30~40s, and the sizing tension is 50~60N.

[0015] The high-modulus recycled viscose fiber composite fabric prepared by the preparation method has a breaking modulus of 520~580 N / mm², a wet modulus retention rate of ≥85%, and a moisture regain of ≥13%.

[0016] In summary, the beneficial effects of this invention are as follows: This invention uses an aqueous dispersion of cellulose nanocrystals as a rigid nano-reinforcement and an aqueous polyurethane prepolymer as a flexible interface layer. Through the "bridging" effect of the silane coupling agent and the hot-pressing process, a "rigid and flexible" micro-composite structure is achieved. While significantly improving the modulus, it avoids material embrittlement. At the same time, through in-situ polymerization, the aqueous polyurethane and cellulose nanocrystals form an interpenetrating network. Combined with the chemical bonding of the silane coupling agent and the physical interlocking of the hot-pressing, a multi-level and firm bond between the reinforcing phase, the matrix phase, and the interface phase is achieved, ensuring the durability of the performance. Detailed Implementation

[0017] The specific embodiments of the present invention will be further described below. These embodiments do not constitute a limitation on the present invention.

[0018] Example 1 A method for preparing a high-modulus recycled viscose fiber composite fabric includes the following steps: S1. Select recycled viscose short fibers with a fineness of 1.2 dtex and a length of 38 mm, soak them in deionized water at 25°C for 20 min, and then dry them in an oven at 80°C for 2 h until the fiber moisture content drops to 8%. After combing, uniformly dispersed recycled viscose fibers are obtained.

[0019] S2, the uniformly dispersed regenerated viscose fibers are impregnated in an aqueous dispersion of 2wt% cellulose nanocrystals at a bath ratio of 1:25, and treated with ultrasonic assistance at a power of 300W for 30 minutes. After removal, they are pre-dried at 80℃ for 6 minutes.

[0020] S3 involves impregnating the recycled viscose fiber treated in S2 into a waterborne polyurethane prepolymer with a solid content of 40% for two dips and two nips, with a nip-out ratio of 80%. Then, it is impregnated into an aqueous solution containing 1 wt% ethylenediamine and 0.5 wt% KH-550 and reacted at 50°C for 10 min to carry out in-situ interfacial polymerization. After forming a coating, it is dehydrated at a speed of 2100 r / min for 6 min. It is then pre-dried at 92°C for 35 min, and then heated to 110°C and cured for 2 h to obtain modified recycled viscose fiber.

[0021] S4. Modified recycled viscose fiber and high-modulus polyester staple fiber are mixed at a mass ratio of 70:30. The high-modulus polyester staple fiber has a fineness of 1.0 dtex, a length of 35 mm, and a breaking strength of 5.5 cN / dtex. After blending, the yarn is processed sequentially through carding, drawing, roving, and spinning to obtain the blended yarn. The blending speed is 10 m / min, the blending time is 15 min, the carding speed is 25 m / min, the drawing speed is 90 m / min, the roving twist is 35 twists / 10 cm, the spinning twist is 80 twists / 10 cm, the weaving speed is 300 r / min, the warp density is 380 ends / 10 cm, and the weft density is 280 ends / 10 cm. The yarn is then woven on an air-jet loom to obtain the initial composite fabric.

[0022] S5. After hot rolling, setting, washing and drying, the initial composite fabric is obtained by hot rolling at 125℃, hot rolling pressure at 0.3MPa, hot rolling speed at 6m / min, setting temperature at 130℃, setting time at 40s, and setting tension at 50N.

[0023] Example 2 A method for preparing a high-modulus recycled viscose fiber composite fabric includes the following steps: S1. Select recycled viscose short fibers with a fineness of 1.3 dtex and a length of 40 mm, soak them in deionized water at 28℃ for 25 min, and then dry them in an oven at 83℃ for 2.5 h until the fiber moisture content drops to 9%. After combing, uniformly dispersed recycled viscose fibers are obtained.

[0024] S2, the uniformly dispersed regenerated viscose fibers are impregnated in an aqueous dispersion of 1 wt% cellulose nanocrystals at a bath ratio of 1:20, and treated with ultrasonic assistance at a power of 350W for 40 minutes. After removal, they are pre-dried at 80℃ for 5 minutes.

[0025] S3 involves impregnating the recycled viscose fiber treated in S2 into a waterborne polyurethane prepolymer with a solid content of 40% for two dips and two nips, with a nip rate of 80%. Then, it is impregnated into an aqueous solution containing 1 wt% ethylenediamine and 0.5 wt% KH-550 and reacted at 50°C for 12 min to carry out in-situ interfacial polymerization. After forming a coating, it is dehydrated at a speed of 2200 r / min for 8 min. It is then pre-dried at 93°C for 35 min, and then heated to 120°C and cured for 2 h to obtain modified recycled viscose fiber.

[0026] S4. Modified recycled viscose fiber and high-modulus polyester staple fiber were mixed at a mass ratio of 70:30. The high-modulus polyester staple fiber had a fineness of 1.0 dtex, a length of mm, and a breaking strength of 5.8 cN / dtex. After blending, the yarn was processed sequentially through carding, drawing, roving, and spinning to obtain the blended yarn. The blending speed was 12 m / min, the blending time was 20 min, the carding speed was 30 m / min, the drawing speed was 90 m / min, the roving twist was 38 twists / 10 cm, the spinning twist was 85 twists / 10 cm, the weaving speed was 320 r / min, the warp density was 400 ends / 10 cm, and the weft density was 320 ends / 10 cm. The yarn was then woven on an air-jet loom to obtain the initial composite fabric.

[0027] S5. After hot rolling, setting, washing and drying, the initial composite fabric is obtained by hot rolling at 135℃, hot rolling pressure at 0.3MPa, hot rolling speed at 7m / min, setting temperature at 140℃, setting time at 40s, and setting tension at 60N.

[0028] Example 3 A method for preparing a high-modulus recycled viscose fiber composite fabric includes the following steps: S1. Select recycled viscose short fibers with a fineness of 1.5 dtex and a length of 42 mm, soak them in deionized water at 28℃ for 30 min, and then dry them in an oven at 85℃ for 4 h until the fiber moisture content drops to 10%. After combing, uniformly dispersed recycled viscose fibers are obtained.

[0029] S2, the uniformly dispersed regenerated viscose fibers are impregnated in an aqueous dispersion of cellulose nanocrystals with a mass fraction of 3wt% at a bath ratio of 1:30. The mixture is then treated with ultrasonic assistance at a power of 350W for 40 minutes. After removal, the fibers are pre-dried at a temperature of 80℃ for 5 minutes.

[0030] S3 involves impregnating the recycled viscose fiber treated in S2 into a waterborne polyurethane prepolymer with a solid content of 40% for two dips and two nips, with a nip-out ratio of 80%. Then, it is impregnated into an aqueous solution containing 1 wt% ethylenediamine and 0.5 wt% KH-550 and reacted at 50°C for 15 min to carry out in-situ interfacial polymerization. After forming a coating, it is dehydrated at a speed of 2500 r / min for 8 min. It is then pre-dried at 90°C for 30 min, and then heated to 115°C and cured for 2.5 h to obtain modified recycled viscose fiber.

[0031] S4. Modified recycled viscose fiber and high-modulus polyester staple fiber were mixed at a mass ratio of 70:30. The high-modulus polyester staple fiber had a fineness of 1.2 dtex, a length of 38 mm, and a breaking strength of 6.0 cN / dtex. After blending, the yarn was processed sequentially through carding, drawing, roving, and spinning to obtain the blended yarn. The blending speed was 12 m / min, the blending time was 20 min, the carding speed was 25 m / min, the drawing speed was 100 m / min, the roving twist was 40 twists / 10 cm, the spinning twist was 85 twists / 10 cm, the weaving speed was 330 r / min, the warp density was 420 ends / 10 cm, and the weft density was 320 ends / 10 cm. The yarn was then woven using an air-jet loom to obtain the initial composite fabric.

[0032] S5. After hot rolling, setting, washing and drying, the initial composite fabric is obtained by hot rolling at 125℃, hot rolling pressure at 0.3MPa, hot rolling speed at 7m / min, setting temperature at 140℃, setting time at 40s, and setting tension at 60N.

[0033] Comparative Example 1 Without performing steps S2 and S3, the recycled viscose fiber treated in step S1 is directly selected and mixed with high-modulus polyester staple fiber at a mass ratio of 70:30. The remaining steps are exactly the same as in Example 1, and a conventional recycled viscose composite fabric is prepared.

[0034] Testing standards and methods 1. Modulus of rupture and tensile strength: Tested according to GB / T 3923.1-2013 "Textiles - Tensile properties of fabrics - Part 1: Determination of tensile strength and elongation at break - Strip method", with a clamping length of 200 mm and a tensile speed of 100 mm / min. The warp and weft directions were tested, and the average value was taken. 2. Wet modulus retention rate: The wet modulus of rupture was tested according to GB / T 3916-2013 "Determination of breaking strength of yarn - Wet method", and the ratio of wet modulus to dry modulus was calculated, i.e., wet modulus retention rate = (wet modulus of rupture / dry modulus of rupture) × 100%; 3. Tear strength: Tested according to GB / T 3917.2-2009 "Textiles - Tear properties of fabrics - Part 2: Determination of tongue-shaped tear strength", taking the average value of the warp and weft directions; 4. Moisture regain (hygroscopicity): Tested in accordance with GB / T 9995-2013 "Determination of moisture content and moisture regain of textiles" using an oven.

[0035] The specific test data is shown in Table 1 below.

[0036] Table 1

[0037] The composite fabrics prepared in Examples 1-3 of this invention have a breaking modulus of 520-580 N / mm², which is 48%-66% higher than that of the unmodified Comparative Example 1 (380 N / mm²). This indicates that the dual modification technology of "silane coupling agent-nanoparticles" can significantly improve the modulus of the composite fabric. The synergistic effect of the two modifiers is obvious and superior to the single modification scheme.

[0038] The wet modulus retention rates of Examples 1-3 of the present invention reached 85.2%-88.5%, far exceeding that of Comparative Example 1 (48.6%), indicating that the modification and composite process of the present invention can effectively improve the wet mechanical stability of the fabric and solve the inherent defect of low wet modulus of traditional recycled viscose fabrics.

[0039] The mechanical properties such as breaking strength and tear strength of Examples 1-3 of the present invention are significantly better than those of Comparative Example 1, indicating that the technical solution of the present invention can improve the modulus while taking into account other mechanical properties of the fabric.

[0040] The moisture regain rates of Examples 1-3 of the present invention were 13.1%-13.8%, which were not significantly different from Comparative Example 1. This indicates that the modification and composite process of the present invention did not affect the moisture absorption and softness of the fabric, and maintained the inherent advantages of recycled viscose fiber.

[0041] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art can make various modifications or equivalent substitutions to the present invention within the scope of its essence and protection. Such modifications or equivalent substitutions should also be considered to fall within the protection scope of the present invention.

Claims

1. A method for preparing a high-modulus recycled viscose fiber composite fabric, characterized in that, Includes the following steps: S1. Select recycled viscose short fibers, soak them in deionized water, and then dry them in an oven until the fiber moisture content drops to 8-10%. After combing, uniformly dispersed recycled viscose fibers are obtained. S2, the uniformly dispersed regenerated viscose fiber is immersed in an aqueous dispersion of cellulose nanocrystals, treated under ultrasonic assistance, and then pre-dried after removal; S3 involves sequentially immersing the recycled viscose fibers treated in S2 into an aqueous polyurethane prepolymer and a solution containing a chain extender and a silane coupling agent, respectively, to carry out an in-situ interfacial polymerization reaction. After forming a coating, the fibers are dehydrated, dried, and cured to obtain modified recycled viscose fibers. S4, modified recycled viscose fiber is mixed with high modulus polyester staple fiber, and after blending, it is successively processed through carding, drawing, roving and spinning to prepare blended yarn, which is then woven using an air-jet loom to obtain the initial composite fabric. S5, after the initial composite fabric is hot-rolled, shaped and washed and dried, a high-modulus recycled viscose fiber composite fabric is obtained.

2. The method for preparing a high-modulus recycled viscose fiber composite fabric according to claim 1, characterized in that: In step S1, the fineness of the recycled viscose short fibers is 1.2~1.5 dtex and the length is 38~42 mm. The soaking temperature of the deionized water is 25~30℃ and the soaking time is 20~30 min. The drying temperature of the oven is 80~85℃ and the drying time is 2~3 h.

3. The method for preparing a high-modulus recycled viscose fiber composite fabric according to claim 1, characterized in that: The preparation method of the aqueous dispersion of cellulose nanocrystals in step S2 is as follows: microcrystalline cellulose is added to a sulfuric acid solution with a concentration of 60~65wt%, and acidified at 45~50℃ for 60~90min. Then, it is centrifuged and dialyzed until neutral to obtain an aqueous dispersion of cellulose nanocrystals with a mass fraction of 1~3wt%. The bath ratio of the regenerated viscose short fibers to the aqueous dispersion of medium cellulose nanocrystals is 1:20~1:

30.

4. The method for preparing a high-modulus recycled viscose fiber composite fabric according to claim 1, characterized in that: In step S2, the ultrasonic treatment power is 250~350W, the time is 20~40min, the pre-drying temperature is 80℃, and the pre-drying time is 5~7min.

5. The method for preparing a high-modulus recycled viscose fiber composite fabric according to claim 1, characterized in that: In step S3, the solid content of the waterborne polyurethane prepolymer is 40%, and the recycled viscose fiber is impregnated in the waterborne polyurethane prepolymer, with two dips and two nips, and a nip-out rate of 80%.

6. The method for preparing a high-modulus recycled viscose fiber composite fabric according to claim 1, characterized in that: In step S3, the solution containing the chain extender and silane coupling agent is an aqueous solution containing 1 wt% ethylenediamine and 0.5 wt% KH-550. The regenerated viscose fiber is impregnated in the solution containing the chain extender and silane coupling agent and reacted at 50°C for 10-15 minutes.

7. The method for preparing a high-modulus recycled viscose fiber composite fabric according to claim 1, characterized in that: In step S3, the dehydration speed is 2000~2500 r / min, the dehydration time is 5~8 min, and the specific steps for drying and curing are as follows: first, pre-dry at 90~95℃ for 30~40 min, then raise the temperature to 110~120℃ and keep it warm for 2~2.5 h.

8. The method for preparing a high-modulus recycled viscose fiber composite fabric according to claim 1, characterized in that: In step S4, the mass ratio of modified recycled viscose fiber to high-modulus polyester staple fiber is 70:

30. The high-modulus polyester staple fiber has a fineness of 1.0~1.2 dtex, a length of 35~38 mm, a breaking strength ≥5.5 cN / dtex, a blending speed of 10~15 m / min, a blending time of 15~20 min, a carding speed of 25~30 m / min, a drawing speed of 80~100 m / min, a roving twist of 35~40 twists / 10 cm, a yarn twist of 80~90 twists / 10 cm, a weaving speed of 300~350 r / min, a warp density of 380~420 threads / 10 cm, and a weft density of 280~320 threads / 10 cm.

9. The method for preparing a high-modulus recycled viscose fiber composite fabric according to claim 1, characterized in that: In step S5, the hot rolling temperature for hot rolling composite is 125~135℃, the hot rolling pressure is 0.3~0.4MPa, the hot rolling speed is 6~7m / min, the sizing temperature is 130~140℃, the sizing time is 30~40s, and the sizing tension is 50~60N.

10. A high-modulus recycled viscose fiber composite fabric prepared by any one of the preparation methods according to claims 1 to 9, characterized in that, The high-modulus recycled viscose fiber composite fabric has a breaking modulus of 520~580 N / mm², a wet modulus retention rate of ≥85%, and a moisture regain rate of ≥13%.

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