Polylactic acid / nanocellulose composite fiber dyeing process

Abstract

The invention relates to the technical field of chemical textile processing, and discloses a polylactic acid / nanocellulose composite fiber dyeing process, which comprises a spinning solution preparation process, a spinning process and a dyeing process, and the spinning solution preparation process comprises the following steps: uniformly mixing a nanocellulose suspension, a polylactic acid solution and an additive, standing at 30-80 DEG C for 1-2 hours, performing high-energy electron beam radiation to form gel, and washing the gel to obtain a hydrogel spinning solution; in the spinning process, the hydrogel spinning solution is fed into wet spinning equipment for spinning to form fibers, the fibers are subjected to high-energy electron beam radiation drying reinforcement to obtain fiber filaments, the irradiation dose is 10-50 kGy, and the irradiation time is 3-5 minutes. The preparation method disclosed by the invention is simple, feasible, green and environment-friendly, the dye uptake of the prepared composite fiber reaches 80%, the strength of the composite fiber is enhanced by 1-2 times, and the fibrillation resistance is improved by 1-2 times.

Description

Technical Field

[0001] The invention relates to the technical field of textile processing, in particular to a dyeing process for polylactic acid / nanocellulose composite fibers. Background Art

[0002] Polylactic acid fiber is a polyester fiber made by spinning polylactic acid ester obtained from natural sugars in agricultural products such as corn and grains. Polylactic acid fiber is biodegradable, green and environmentally friendly, and has excellent performance. Polylactic acid fiber is suitable for dyeing with disperse dyes. However, polylactic acid fiber has shortcomings such as low dye uptake, low dye fastness, and low dye utilization. For example, in the Chinese invention patent application with application number CN202010905523.6, a polylactic acid fiber bobbin dyeing process is disclosed, which includes the following steps: Step 1: Loosening the bobbin; through a loose winding machine, the yarns of different specifications are turned onto the plastic bobbin as planned, certain defects and impurities on the yarn are removed, and the yarn quality is improved. The knots of the yarn on the bobbin should be small and firm, and a larger yarn winding angle is adopted; Step 2: Cage loading; the loose bobbin yarn is loaded onto the yarn rod of the yarn cage as required, and fixed in preparation for dyeing; Step 3: Dyeing; the bobbin yarn is placed on the bobbin fixing frame in the bobbin yarn dyeing device On; according to the bath ratio of 1:1-50, the yarn is pre-treated with a dyeing pretreatment liquid, and a diffusing agent NN is added to the dye, and the alkalinity is adjusted; Step 4: Dehydration; After the yarn dyeing process is completed, it is dehydrated, and the dehydration is completed by a centrifugal dehydrator at high speed; Step 5: Drying; The yarn dehydrated in step 4 is dried in a high-frequency dryer, and the yarn is dried on the upper and lower heating plates; and an exhaust fan is fixedly installed on the rear side of the high-frequency dryer to exhaust the steam; Step 6: Rewinding; The dyed yarn is turned over to become a well-formed yarn that meets the unwinding requirements.

[0003] For another example, in the Chinese invention patent application with application number CN200610012779.4, a dyeing process for polylactic acid fiber / cotton blended woven fabric is disclosed, which includes a. a desizing process, b. a scouring and bleaching process, c. a mercerizing process, and d. a dyeing process.

[0004] Moreover, the cellulose fibers obtained by the traditional cellulose fiber processing technology have low strength and poor anti-fibrillation performance, and the fabrics made of the fibers are prone to shedding and pilling. Summary of the Invention

[0005] In view of the deficiencies in the prior art, the present invention provides a polylactic acid / nanocellulose composite fiber dyeing process, which has a simple process and can achieve good dyeing effect while improving the strength and anti-fibrillation performance of the polylactic acid / nanocellulose composite fiber.

[0006] To achieve the above object, the present invention provides the following technical solution: a polylactic acid / nanocellulose dyeing process, comprising a spinning solution preparation process, a spinning process and a dyeing process, The spinning solution preparation process comprises uniformly mixing a nanocellulose suspension, a polylactic acid solution, and an additive, standing at 30-80° C. for 1-2 hours, and irradiating the mixture with a high-energy electron beam to form a gel, and washing the gel with water to obtain a hydrogel spinning solution, wherein the irradiation dose of the high-energy electron beam is 10-50 kGy, and the irradiation time is 20 to 40 minutes. The mass ratio of the polylactic acid solution to the nanocellulose solution is 10:1-1:1, and the mass ratio of the polylactic acid solution to the additive solution is 10:1-1:1. The polylactic acid solution is prepared by dispersing polylactic acid in an organic solvent, and the mass concentration of the polylactic acid is 5-10%. The nanocellulose suspension is prepared by dispersing cellulose fibers with a length of 10-100 nm in water, and the mass concentration of the cellulose is 5-20%. The spinning process is to feed the hydrogel spinning solution into a wet spinning device to spin fibers, and the fibers are dried and strengthened by high-energy electron beam radiation to obtain fiber filaments, wherein the radiation dose is 10-50 kGy and the irradiation time is 3-5 minutes; The dyeing process comprises the following steps: a weight ratio of dye to fiber of 1-10%, a bath ratio of 1:45-55, an amount of dispersant NN of 0.8-1.2 g / L, a pH value of the dyeing solution of 4.8-5.2, heating the solution to 58-62°C at a rate of 1.5-2.5°C / min, adding the fiber, heating the solution to a dyeing temperature of 108-112°C at a rate of 0.8-1.2°C / min, and maintaining the temperature for dyeing for 18-22 minutes; then cooling the solution to 58-62°C, adding 2.5-3.5 g / L of hydrosulfite, 2.5-3.5 g / L of anhydrous sodium carbonate, and 2.5-3.5 g / L of detergent to remove floating color on the fiber, and then fully washing the solution with water, drying the solution, or performing a post-processing process.

[0007] In a preferred embodiment of the present invention, the hydrogel spinning solution is spun through the spinneret of a spinning apparatus, and the fibers are then passed into a water coagulation bath and washed, drawn, and dried by high-energy electron beam radiation to produce polylactic acid / nanocellulose fibers. The fiber drawing speed is controlled at 0 to 100 cm / min.

[0008] As a preferred embodiment of the present invention, the organic solvent is one or a mixture of two or more of N,N-dimethylformamide, tetrahydrofuran, 1,4-dioxane, chloroform and acetone.

[0009] As a preferred embodiment of the present invention, the additive is polyethylene glycol, glycerol, carboxymethyl chitosan, carboxymethyl cellulose, polyvinyl alcohol or polyethylene oxide.

[0010] As a preferred embodiment of the present invention, the cellulose fiber is sugarcane fiber.

[0011] As a preferred embodiment of the present invention, the molecular weight of the polylactic acid is 10,000 to 270,000.

[0012] As a preferred embodiment of the present invention, the dye is a mixture of disperse dye and reactive dye.

[0013] As a preferred embodiment of the present invention, the disperse dye is azo-type disperse red 74, disperse blue 79 or disperse yellow 54; the reactive dye is reactive red CN-3B, reactive blue CN-2G or reactive yellow CN-EX.

[0014] Compared with existing technologies, the present invention's preparation method is simple, environmentally friendly, and conducive to industrialization. The dyeing process for the polylactic acid / nanocellulose composite fibers achieves a dye uptake of 80%, increases fiber strength by 1-2 times, and enhances anti-fibrillation resistance by 1-2 times. Using the present invention's technical solution, the polylactic acid / nanocellulose composite fibers undergo two irradiation treatments. The first irradiation enhances pre-crosslinking and condensation of the hydroxyl or carboxyl groups between the nanocellulose and polylactic acid, forming appropriate ether and ester bonds to create a spinning solution suitable for spinning. The second irradiation strengthens the hydroxyl or carboxyl groups in the spinning components through radiation, further crosslinking and condensing them. This enhances fiber strength and anti-fibrillation resistance, while also increasing the affinity of disperse dyes for the fibers and improving their dyeing performance. By utilizing hydrogel spinning of the polylactic acid / nanocellulose composite fibers, the present invention eliminates the use of the N-methylmorpholine N-oxide (NMM) solvent used in traditional cellulose fiber spinning processes, eliminating the need for solvent recovery and reducing equipment investment. DETAILED DESCRIPTION

[0015] In order to better understand the technical solution of the present invention, it is described in more detail below with reference to embodiments.

[0016] Example 1 Cellulose is dispersed into a nanocellulose suspension in water using a high-speed shearing machine from sugarcane fiber to obtain a 10% nanocellulose suspension solution. Polylactic acid (produced by Aladdin Reagent (Shanghai) Co., Ltd., model Mw~60,000, the same below) is dissolved in a mixed solution of dichloromethane / N,N-dimethylformamide (the volume ratio of the two is 4:1) to obtain a polylactic acid solution with a mass fraction of 5%. The nanocellulose suspension solution, polylactic acid solution, and polyethylene glycol solution are mixed evenly in a mass ratio of 6:3:1, and then allowed to stand at 50°C for 12 hours. Then, the mixture is irradiated with a high-energy electron beam with a radiation dose of 30 kGy to obtain a polylactic acid / nanocellulose gel sample. The gel sample is immersed in deionized water, and the water is changed every 3 hours, and this is repeated 5 to 8 times. The gel is washed with water to replace the organic solvent, and the water content of the hydrogel is 60% (mass percentage, the same below) to form a hydrogel spinning solution. The spinning solution was wet-spinned using a spinning apparatus. The resulting fibers were irradiated with a high-energy electron beam for 5 minutes at a dose of 30 kGy and then subjected to secondary drying and strengthening. The hydrogel spinning solution was then spun through the spinneret of the spinning apparatus. The fibers were then washed, drawn, and irradiated to produce polylactic acid / nanocellulose fibers in a water coagulation bath. The drawing line speed was controlled at 15 cm / min. The dye was prepared at room temperature: 1% Disperse Yellow 54 (on fabric weight, 0.5%), 1% Reactive Yellow CN-EX (on fabric weight, 0.5%), and 1 g / L dispersant NN, with a bath ratio of 1:50. The pH was adjusted to 5 using acetic acid and sodium acetate. After the dye solution was prepared, the temperature was increased from room temperature to 60°C at a rate of 2°C / min. The polylactic acid / nanocellulose composite fibers were then added to initiate dyeing. The temperature was then increased to 110°C at a rate of 1°C / min and maintained at this temperature for 20 minutes. Then, the temperature is lowered from 110°C to 60°C within 30 minutes. A cleaning solution is prepared by adding 3g / L of hydrosulfite, 3g / L of anhydrous sodium carbonate, and 3g / L of detergent 6501 (detergent 6501 is a nonionic surfactant, traded under the international name Ninl 6501; a 1:1 ratio can be used, the same below. Of course, the present invention is not limited to this type of detergent; other detergents used in the field of fiber dyeing can also be used) to remove loose color from the fibers and improve wet fastness. After cleaning, the fibers are thoroughly rinsed with water, air-dried, or subjected to post-processing.

[0017] The wet spin-spinning method of Example 1 was used to dye the fiber with a dye uptake of 70%. The strength of the wet spin-spinning method was doubled to 80°C N·tex. -1Fiber mechanical properties test (the same below): Fiber mechanical properties were tested using a single-filament tensile tester in accordance with GB / T 14337-2008, "Test Method for Tensile Properties of Chemical Staple Fibers." Using a clamping distance of 20 mm and a tensile speed of 20 mm / minute, fiber samples approximately 40 mm in length were cut with scissors and placed flat on the operating panel. A suitable clamp was used to clamp one end of the fiber, and tweezers were used to grasp the other end. The fiber was placed in the instrument's clamp and stretched until it broke. Multiple tests were performed on the fiber sample, and the results were averaged and recorded. The fiber's anti-fibrillation performance was doubled, with a wet friction value reaching 180 seconds. The anti-fibrillation performance test (the same below) employed a wet friction method, in which the fiber was rubbed under wet conditions with frictional stress until it broke. The wet friction value was defined as the time from the start of friction to fiber breakage. A higher wet friction value indicates that the fibrils are less likely to be separated from the fiber, indicating a higher anti-fibrillation performance.

[0018] Example 2 Sugarcane fiber was dispersed into a nanocellulose suspension in water using a high-speed shearing machine, yielding a 15% nanocellulose suspension. Polylactic acid (PLA) was then dissolved in a mixture of chloroform and N,N-dimethylformamide (3:1 by volume) to yield an 8% PLA solution. The nanocellulose suspension, PLA solution, and glycerol solution were mixed at a mass ratio of 7:2:1 and allowed to stand at 30°C for 24 hours. The mixture was then irradiated with a high-energy electron beam (50 kGy) to produce a reinforced cross-linked gel sample. The gel sample was then immersed in deionized water, with the water changed every 3 hours for 5-8 cycles. The gel was then washed to displace the organic solvent, resulting in a hydrogel with a water content of 70%. This formed a nanocellulose / PLA hydrogel spinning solution. The spinning solution was then wet-spun using a spinneret, irradiated with a high-energy electron beam (50 kGy) for 3 minutes, and then dried for a secondary strengthening treatment. The hydrogel spinning solution was spun through the spinneret of the spinning equipment. The filaments entered a water coagulation bath, where they were washed, drawn, and then irradiated to produce polylactic acid / nanocellulose fibers. The drawing and stretching speed was controlled at 25 cm / min. The dye was prepared at room temperature: 2% Disperse Red 74 (on fabric weight, owf), 2% Reactive Red CN-3B (on fabric weight, owf), and 1 g / L dispersant NN, with a bath ratio of 1:50. The pH was adjusted to 5 using acetic acid and sodium acetate. After the dye solution was prepared, the temperature was raised from room temperature to 60°C at a rate of 2°C / min. The polylactic acid / nanocellulose composite fibers were then added to begin dyeing. The temperature was then raised at a rate of 1°C / min to 110°C and held for 20 minutes. The temperature was then cooled from 110°C to 60°C over a controlled period of 25 minutes. Add 3g / L of hydrosulfite, 3g / L of anhydrous sodium carbonate, and 3g / L of detergent 6501 to remove loose color from the fiber and improve wet fastness. After cleaning, rinse thoroughly with water, dry or perform post-treatment. The wet-spinning fiber of Example 2 has a dye uptake of 80%, and the strength of the fiber obtained by wet-spinning is increased by 2 times to 120CN•tex. -1 , the anti-fibrillation performance is increased by 2 times to 270s.

[0019] Example 3 Sugarcane fiber was dispersed in water using a high-speed shearing machine to form a nanocellulose suspension, yielding a 20% nanocellulose suspension. Polylactic acid (PLA) was then dissolved in a 4:1 (volume ratio) mixture of chloroform and N,N-dimethylformamide to yield an 8% (mass fraction) PLA solution. The nanocellulose suspension, PLA solution, and carboxymethyl cellulose solution were then mixed at a mass ratio of 6:2:2 and allowed to stand at 30°C for 24 hours. The mixture was then irradiated with a high-energy electron beam (HEB) at a dose of 45 kGy for 30 minutes to yield a reinforced cross-linked nanocellulose / PLA gel sample. The gel sample was then immersed in deionized water, with the water changed every 3 hours for 5-8 cycles. The gel was then washed to displace the organic solvent, resulting in a hydrogel with a water content of 50%, forming a nanocellulose / PLA hydrogel spinning solution. The spinning solution was then wet-spun using a spinneret and subjected to a secondary drying treatment with a 30 kGy HEB irradiation for 5 minutes. The hydrogel spinning solution was spun through the spinneret of the spinning equipment, then placed in a water coagulation bath for washing, drawing, and radiation drying to produce polylactic acid / nanocellulose fibers. The drawing line speed was controlled at 35 cm / min. The dye was prepared at room temperature: 3% Disperse Blue 79 (on fabric weight, owf), 3% Reactive Blue CN-2G (on fabric weight, owf), and 1 g / L dispersant NN, with a bath ratio of 1:50. The pH was adjusted to 5 using acetic acid and sodium acetate. After the dye solution was prepared, the temperature was raised from room temperature to 60°C at a rate of 2°C / min. The polylactic acid / nanocellulose composite fibers were then added to begin dyeing. The temperature was then raised at 1°C / min to 110°C and held for 20 minutes. The temperature was then cooled from 110°C to 60°C over a controlled period of 30 minutes. Add 3g / L of hydrosulfite, 3g / L of anhydrous sodium carbonate, and 3g / L of detergent 6501 to remove loose color from the fiber and improve wet fastness. After cleaning, rinse thoroughly with water, dry or perform post-treatment. The wet-spinning fiber of Example 3 has a dye uptake of 78%, and the strength of the fiber obtained by wet-spinning is increased by 2.5 times to 100 CN•tex. -1 , the anti-fibrillation performance is increased by 1 times to 180s.

[0020] Example 4 Sugarcane fiber was dispersed in water using a high-speed shearing machine to form a nanocellulose suspension, yielding a 5% nanocellulose suspension. Polylactic acid (PLA) was then dissolved in a mixture of dichloromethane and N,N-dimethylformamide (3:1 by volume) to yield an 8% PLA solution. The nanocellulose suspension, PLA solution, and polyvinyl alcohol solution were mixed at a mass ratio of 8:1:1 and allowed to stand at 30°C for 24 hours. The mixture was then irradiated with a high-energy electron beam (HEB) at a dose of 50 kGy for 30 minutes to yield a reinforced cross-linked nanocellulose / PLA gel sample. The gel sample was then immersed in deionized water, with the water changed every 3 hours for 5-8 cycles. The gel was then washed to displace the organic solvent, resulting in a hydrogel with a water content of 30%, forming a nanocellulose / PLA hydrogel spinning solution. The spinning solution was then wet-spun using a spinneret and subjected to a secondary drying treatment with a HEB irradiation dose of 40 kGy for 3 minutes. The hydrogel spinning solution was spun through the spinneret of the spinning equipment. The fibers entered a water coagulation bath and were washed, drawn, and then irradiated to produce polylactic acid / nanocellulose fibers. The drawing and stretching line speed was controlled at 40 cm / min. The dye was prepared at room temperature: Disperse Yellow 54 1.5% (on fabric weight, owf), Reactive Yellow CN-EX 1.5% (on fabric weight, owf), and diffusing agent NN 1 g / L, with a bath ratio of 1:50. The pH was adjusted to 5 using acetic acid and sodium acetate. After the dye solution was prepared, the temperature was raised from room temperature to 60°C at a rate of 2°C / min. The polylactic acid / nanocellulose composite fibers were then added to begin dyeing. The temperature was then raised at 1°C / min to 110°C and held for 20 minutes. The temperature was then cooled from 110°C to 60°C over a controlled period of 30 minutes. Add 3g / L of hydrosulfite, 3g / L of anhydrous sodium carbonate, and 3g / L of detergent 6501 to remove loose color from the fiber and improve wet fastness. After cleaning, rinse thoroughly with water, dry or perform post-treatment. The wet-spinning fiber of Example 4 has a dye uptake of 76%, and the strength of the fiber obtained by wet-spinning is increased by 1.5 times to 100CN•tex. -1 , the anti-fibrillation performance is improved by 1.2 times, reaching 200s.

[0021] Example 5 Sugarcane fiber was dispersed in water using a high-speed shearing machine to form a nanocellulose suspension, yielding a 15% nanocellulose suspension. Polylactic acid (PLA) was then dissolved in a dichloromethane / N,N-dimethylformamide (4:1 by volume) mixture to yield an 8% PLA solution. The nanocellulose suspension, PLA solution, and polyethylene glycol solution were mixed in a 5:3:2 mass ratio and allowed to stand at 30°C for 24 hours. The mixture was then irradiated with a high-energy electron beam (50 kGy) to produce a reinforced cross-linked nanocellulose / PLA gel sample. The gel sample was then immersed in deionized water, with the water changed every 3 hours for 5-8 cycles. The gel was then washed to displace the organic solvent, resulting in a hydrogel with a water content of 50%, forming a nanocellulose / PLA hydrogel spinning solution. The spinning solution was then wet-spun using a spinneret and subjected to a secondary drying treatment with a high-energy electron beam (50 kGy) for 5 minutes. The hydrogel spinning solution was spun through the spinneret of the spinning equipment, then placed in a water coagulation bath for washing, drawing, and radiation drying to produce polylactic acid / nanocellulose fibers. The drawing line speed was controlled at 30 cm / min. The dye was prepared at room temperature: 1.5% Disperse Blue 79 (on fabric weight, owf), 1.5% Reactive Blue CN-2G (on fabric weight, owf), 0.2 g / L anionic surfactant AES, 0.4 g / L leveling agent SL, with a bath ratio of 1:30. The pH was adjusted to 5 using acetic acid and sodium acetate. After the dye solution was prepared, the temperature was raised from room temperature to 60°C at a rate of 2°C / min. The polylactic acid / nanocellulose composite fibers were then added to initiate dyeing. The temperature was then raised at 1°C / min to 110°C and held for 20 minutes. The temperature was then cooled from 110°C to 60°C over a controlled period of 30 minutes. Add 3g / L of hydrosulfite, 3g / L of anhydrous sodium carbonate, and 3g / L of detergent 6501 to remove loose color from the fiber and improve wet fastness. After cleaning, rinse thoroughly with water, dry or perform post-treatment. The wet-spinning fiber of Example 5 has a dye uptake of 79%, and the strength of the fiber obtained by wet-spinning is increased by 2.8 times to 112CN•tex. -1 , the anti-fibrillation performance is increased by 1 times to 180s.

[0022] Comparative Example 1 The spinning solution obtained by the preparation method of Example 1 was spun without radiation cross-linking and without secondary radiation process to prepare composite fibers for dyeing.

[0023] Sugarcane fiber was dispersed into a nanocellulose suspension in water using a high-speed shearing machine, yielding a 10% nanocellulose suspension. Polylactic acid (PLA) was then dissolved in a mixture of dichloromethane and N,N-dimethylformamide (4:1 by volume) to yield a 5% PLA solution. The nanocellulose suspension, PLA solution, and polyethylene glycol solution were then mixed at a mass ratio of 6:3:1 and allowed to stand at 50°C for 12 hours to yield a PLA / nanocellulose gel sample. The gel sample was then immersed in deionized water, changing the water every 3 hours for 5-8 cycles. The gel was then washed to displace the organic solvent, resulting in a hydrogel with a water content of 60%. The solvent was then displaced from the gel to form a hydrogel spinning solution. The spinning solution was then spun through a wet spinneret, passed through the spinnerets, and the fibers were then placed in a water coagulation bath, washed, drawn, and dried with hot air to produce PLA / nanocellulose fibers. The drawing line speed was controlled at 15 cm / min, and the winding-draw speed ratio was 1.5. Hot air drying was performed at 110°C for 30 minutes. The dye was prepared at room temperature: Disperse Yellow 54 1% (on fabric weight, owf), Reactive Yellow CN-EX 1% (on fabric weight, owf), dispersant NN 1g / L, bath ratio 1:50, and pH adjusted to 5 using acetic acid and sodium acetate. After the dye solution was prepared, the temperature was raised from room temperature to 60°C at a rate of 2°C / min. The polylactic acid / nanocellulose composite fibers were then added to begin dyeing. The temperature was then raised at 1°C / min to 110°C and held for 20 minutes. The temperature was then lowered from 110°C to 60°C over a controlled period of 30 minutes. Add 3g / L of hydrosulfite, 3g / L of anhydrous sodium carbonate, and 3g / L of detergent 6501 to remove floating color on the fiber and improve wet fastness. After cleaning, rinse thoroughly with water, dry or perform post-processing. The resulting spun fiber has a dye uptake of 50% and a breaking strength of 30%, which is 56CN•tex. -1 , the fiber's anti-fibrillation performance decreased by 40% to 108s.

[0024] Comparative Example 2 Sugarcane fiber was dispersed into a nanocellulose suspension in water using a high-speed shearing machine, yielding a 15% nanocellulose suspension. Polylactic acid (PLA) was then dissolved in a mixture of chloroform and N,N-dimethylformamide (3:1 by volume) to yield an 8% PLA solution. The nanocellulose suspension, PLA solution, and glycerol solution were then mixed at a mass ratio of 7:2:1 and allowed to stand at 30°C for 24 hours to yield a reinforced cross-linked gel sample. The gel sample was then immersed in deionized water, changing the water every 3 hours for 5-8 cycles. The gel was then washed to displace the organic solvent, resulting in a hydrogel with a water content of 70%. This formed a nanocellulose / PLA hydrogel spinning solution. The spinning solution was then spun through a wet spinneret, passed through the spinneret, and the fibers were then washed, drawn, and dried with hot air to produce PLA / nanocellulose fibers. The drawing line speed was controlled at 15 cm / min, and the winding-draw speed ratio was 1.5. Hot air drying was performed at 110°C for 5 minutes. The dye was prepared at room temperature: Disperse Red 74 2% (on fabric weight, owf), Reactive Red CN-3B 2% (on fabric weight, owf), Dispersant NN 1g / L, liquor ratio 1:50. The pH was adjusted to 5 with acetic acid and sodium acetate. After the dye solution was prepared, the temperature was raised from room temperature to 60°C at a rate of 2°C / minute. Then, the polylactic acid / nanocellulose composite fibers were added and dyeing began. The temperature was then raised at 1°C / minute to 110°C and held for 20 minutes. The temperature was then lowered from 110°C to 60°C over a 30-minute cooling period. 3g / L of hydrosulfite, 3g / L of anhydrous sodium carbonate, and 3g / L of detergent 6501 were added to remove loose color and improve wet fastness. The fibers were then rinsed thoroughly with water and allowed to air dry or undergo post-processing. Compared with Example 2, the dye uptake of the obtained spun fiber was 55%, and the breaking strength of the obtained spun fiber was reduced by 50%, reaching 60CN•tex. -1 , the fiber's anti-fibrillation performance decreased by 30% to 189s.

[0025] Comparative Example 3 Sugarcane fiber was dispersed into a nanocellulose suspension in water using a high-speed shearing machine, yielding a 15% nanocellulose suspension. Polylactic acid (PLA) was then dissolved in a mixture of chloroform and N,N-dimethylformamide (3:1 by volume) to yield an 8% PLA solution. The nanocellulose suspension, PLA solution, and glycerol solution were then mixed at a mass ratio of 7:2:1 and allowed to stand at 30°C for 24 hours to yield a reinforced cross-linked gel sample. The gel sample was then immersed in deionized water, changing the water every 3 hours for 5-8 times. The gel was then washed to displace the organic solvent, resulting in a hydrogel with a water content of 70%. This formed a nanocellulose / PLA hydrogel spinning solution. The spinning solution was then spun through a wet spinneret, passed through the spinneret, and the filaments were then placed in a water coagulation bath, washed, drawn, and irradiated to produce PLA / nanocellulose fibers. The drawing line speed was controlled at 25 cm / min. The irradiation drying process involved a radiation dose of 50 kGy and a drying time of 3 minutes. The dye was prepared at room temperature: 2% Disperse Red 74 (on fabric weight, owf), 2% Reactive Red CN-3B (on fabric weight, owf), and 1 g / L Dispersant NN, with a bath ratio of 1:50. The pH was adjusted to 5 using acetic acid and sodium acetate. The dye solution was heated from room temperature to 60°C at a rate of 2°C / minute. The polylactic acid / nanocellulose composite fibers were then added and dyeing began. The temperature was then increased at a rate of 1°C / minute to 110°C and held for 20 minutes. The temperature was then lowered from 110°C to 60°C over a 30-minute cooling period. 3 g / L of hydrosulfite, 3 g / L of anhydrous sodium carbonate, and 3 g / L of detergent 6501 were added to remove loose color and improve wet fastness. The solution was then rinsed thoroughly with water and allowed to air dry or undergo post-processing.

[0026] This embodiment adopts one-time irradiation. Compared with the embodiment 2, the dyeing rate of the obtained spun fiber is 65%, and the breaking strength of the obtained spun fiber is reduced by 40%, reaching 72℃N•tex. -1 , the fiber's anti-fibrillation performance is reduced by 50% to 135s.

[0027] Comparative Example 4 Sugarcane fiber is used to disperse cellulose into a nanocellulose suspension in water using a high-speed shearing machine to obtain a 15% nanocellulose suspension solution. Polylactic acid is dissolved in a mixed solution of chloroform / N,N-dimethylformamide (the volume ratio of the two is 3:1) to obtain a polylactic acid solution with a mass fraction of 8%. The nanocellulose suspension solution, polylactic acid solution, and glycerol solution are mixed evenly in a mass ratio of 7:2:1, and then allowed to stand at 30°C for 24 hours. Then, the mixture is irradiated with a high-energy electron beam with a radiation dose of 50kGy to obtain a reinforced cross-linked gel. The gel sample is soaked in deionized water, and the water is changed every 3 hours, repeated 5 to 8 times. The gel is washed with water to replace the organic solvent, and the water content of the hydrogel is 70%, forming a nanocellulose / polylactic acid hydrogel spinning solution. The spinning solution was wet-spinned through a spinning apparatus, then spun through the spinnerets. The fibers were then washed in a water coagulation bath, drawn, and hot-air dried to produce polylactic acid / nanocellulose fibers. The drawing and stretching process was controlled at a line speed of 25 cm / min. The hot-air drying process was conducted at 110°C for 30 minutes. The dye was prepared at room temperature: 2% Disperse Red 74 (on weight offabric, 0.5%), 2% Reactive Red CN-3B (on weight of fabric, 0.5%), and 1 g / L dispersant NN, with a bath ratio of 1:50. The pH was adjusted to 5 using acetic acid and sodium acetate. After the dye solution was prepared, the temperature was raised from room temperature to 60°C at a rate of 2°C / min. The polylactic acid / nanocellulose composite fibers were then added to initiate dyeing. The temperature was then raised to 110°C at a rate of 1°C / min and held for 20 minutes. The temperature was then lowered from 110°C to 60°C over a controlled period of 30 minutes. Add 3g / L of hydrosulfite, 3g / L of anhydrous sodium carbonate, and 3g / L of detergent 6501 to wash away the floating color on the fiber, while improving the wet fastness of the dyeing. After cleaning, rinse thoroughly with water, dry or perform post-processing.

[0028] This embodiment adopts one-time irradiation. Compared with the embodiment 2, the dyeing rate of the obtained spun fiber is 66%, and the breaking strength of the obtained spun fiber is reduced by 30%, reaching 84℃N•tex. -1 , the fiber's anti-fibrillation performance decreased by 40% to 162s.

[0029] The protection scope of the present invention is not limited to this embodiment, and any similar changes made by anyone shall be deemed to be within the protection scope of the present invention.

Claims

1. A polylactic acid / nanocellulose composite fiber dyeing process, comprising a spinning solution preparation process, a spinning process, and a dyeing process, characterized in that: The spinning solution preparation process comprises uniformly mixing a nanocellulose suspension, a polylactic acid solution, and an additive, standing at 30-80° C. for 1-2 hours, and irradiating the mixture with a high-energy electron beam to form a gel, and washing the gel with water to obtain a hydrogel spinning solution, wherein the irradiation dose of the high-energy electron beam is 10-50 kGy, and the irradiation time is 20 to 40 minutes. The mass ratio of the polylactic acid solution to the nanocellulose solution is 10:1-1:1, and the mass ratio of the polylactic acid solution to the additive solution is 10:1-1:

1. The polylactic acid solution is prepared by dispersing polylactic acid in an organic solvent, and the mass concentration of the polylactic acid is 5-10%. The nanocellulose suspension is prepared by dispersing cellulose fibers with a length of 10-100 nm in water, and the mass concentration of the cellulose is 5-20%. The spinning process is to feed the hydrogel spinning solution into a wet spinning device to spin fibers, and the fibers are dried and strengthened by high-energy electron beam radiation to obtain fiber filaments, wherein the radiation dose is 10-50 kGy and the irradiation time is 3-5 minutes; The dyeing process comprises the following steps: a dye to fiber weight ratio of 1-10%, a bath ratio of 1:45-55, an amount of dispersant NN of 0.8-1.2 g / L, a dyeing solution pH of 4.8-5.2, heating the solution to 58-62°C at a rate of 1.5-2.5°C / min, adding the fiber, heating the solution to a dyeing temperature of 108-112°C at a rate of 0.8-1.2°C / min, and maintaining the temperature for dyeing for 18-22 minutes; then cooling the solution to 58-62°C, adding 2.5-3.5 g / L of hydrosulfite, 2.5-3.5 g / L of anhydrous sodium carbonate, and 2.5-3.5 g / L of detergent to remove floating color from the fiber, and then fully washing the fiber with water, drying the fiber, or performing a post-treatment process; The dye is a mixture of disperse dye and reactive dye, the disperse dye is azo type disperse red 74, disperse blue 79 or disperse yellow 54; the reactive dye is reactive red CN-3B, reactive blue CN-2G or reactive yellow CN-EX.

2. A polylactic acid / nanocellulose composite fiber dyeing process according to claim 1, characterized in that: The organic solvent is one or a mixture of two or more of N,N-dimethylformamide, tetrahydrofuran, 1,4-dioxane, chloroform and acetone.

3. A polylactic acid / nanocellulose composite fiber dyeing process according to claim 2, characterized in that: The additive is polyethylene glycol, glycerol, carboxymethyl chitosan, carboxymethyl cellulose, polyvinyl alcohol or polyethylene oxide.

4. A polylactic acid / nanocellulose composite fiber dyeing process according to claim 3, characterized in that: The cellulose fiber is sugarcane fiber.

5. The polylactic acid / nanocellulose composite fiber dyeing process according to claim 4, characterized in that: The molecular weight of the polylactic acid is between 10,000 and 270,000.