An eco-friendly biodegradable fiber and a preparation method thereof

Abstract

The application discloses an ecological and environment-friendly biodegradable fiber and a preparation method thereof. The method is that first, β-cyclodextrin and polyvinyl alcohol (PVA) are subjected to a copolymerization reaction to obtain plasticized modified PVA, then the plasticized modified PVA is used as a skin layer material of the fiber, PBS is used as a core layer material, and the ecological and environment-friendly biodegradable fiber is prepared through a coaxial skin-core spinning method. The ecological and environment-friendly biodegradable fiber prepared by the method has excellent mechanical properties, has the advantage of controllable degradation compared with existing PBS fibers, and has wide market application potential in the field of soft home furnishing which has high requirements on degradation performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of biodegradable fibers, in particular to an ecological and environmentally friendly biodegradable fiber and a preparation method thereof. BACKGROUND

[0002] Polybutylene succinate (PBS) is currently a research hotspot in the field of degradable polyesters. Its outstanding mechanical properties and good biodegradability have led to its rapid development. However, it is susceptible to environmental factors during its service life, which leads to irreversible degradation and aging, thereby affecting its performance.

[0003] Currently, the means to improve the controllability of PBS degradation include blending modification and copolymerization modification. Blending modification is to melt-extrude a blending component that can improve the degradation performance with PBS to obtain a blended fiber. Copolymerization modification is to introduce certain high molecular units into the PBS molecular chain to achieve the purpose of adjusting the biodegradation rate.

[0004] A functional degradable material with controllable degradation period and a preparation method thereof (CN202011020665.0) controls the ratio of modified starch to PBS, the ratio of a mixture of polyglycolic acid and poly-p-dioxanone, and the amount of antioxidant added, and uses a melt blending technology to prepare a full-biodegradable material with a controllable degradation period to meet the needs of products with different degradation periods.

[0005] A preparation method of polybutylene succinate and its copolymer (CN202110125346.4) uses widely available and inexpensive maleic anhydride as a raw material. Compared with traditional processes, it can significantly reduce wastewater and the amount of tetrahydrofuran generated, reduce energy consumption, and ultimately obtain a polybutylene succinate copolymer with a higher molecular weight and effective degradation control.

[0006] The above-mentioned related patents involve blending modification and copolymerization modification of PBS. The blending modification method is simple and easy to operate, but it generally has the shortcomings of poor compatibility between the blending component and PBS and significant performance degradation of the composite fiber. The copolymerization modification process is complicated and the operating conditions are harsh, which is not conducive to practical application and promotion.

[0007] Therefore, it is necessary to develop a controllable degradation PBS fiber preparation method that is simple to operate and has excellent modification effect, which can be applied to the soft furnishing field that promotes green environmental protection, expand the application market of biodegradable materials, and solve the problems of the present application. SUMMARY

[0008] To address the shortcomings of existing technologies, this invention provides an eco-friendly biodegradable fiber and its preparation method. The method involves first copolymerizing β-cyclodextrin with polyvinyl alcohol (PVA) to obtain plasticized modified PVA, which is then used as the sheath material of the fiber, and PBS as the core material. The eco-friendly biodegradable fiber is then prepared through coaxial sheath-core spinning. The eco-friendly biodegradable fiber prepared by this invention exhibits excellent mechanical properties and, compared to existing PBS fibers, possesses the advantage of controllable degradation, making it highly promising for market application in the soft furnishing sector, where high degradation performance is required.

[0009] To achieve the above objectives, the present invention provides the following technical solution.

[0010] An eco-friendly biodegradable fiber consists of a sheath and a core layer. The sheath covers the outside of the core layer. The core layer is composed of PBS, and the sheath is composed of plasticized modified PVA. The melting point of the sheath is 180-200℃, and the melting point of the core layer is 110-120℃.

[0011] The aforementioned eco-friendly biodegradable fiber has a dermis component accounting for 30-70% of the total composition, and a core component accounting for 70-30% of the total composition.

[0012] The eco-friendly biodegradable fiber has a melt index (190℃, 2.16kg) of 5-10g / 10min for both the outer and core layers.

[0013] The aforementioned eco-friendly biodegradable fiber has a diameter of 0.05–0.07 mm.

[0014] This invention also provides a method for preparing an eco-friendly biodegradable fiber as described above. First, β-cyclodextrin is copolymerized with PVA to obtain plasticized modified PVA, which is then used as the sheath material of the fiber and PBS as the core material. The eco-friendly biodegradable fiber is then prepared by coaxial sheath-core spinning.

[0015] As a preferred technical solution:

[0016] The specific steps of the method described above are as follows:

[0017] (1) PVA, β-cyclodextrin, and water were added to a three-necked flask and stirred to dissolve under water bath heating at 80–100°C. The temperature was then lowered to 50–70°C, and a 30% sodium hydroxide aqueous solution was slowly added dropwise while stirring continuously for 8–10 hours. After adding a crosslinking agent and continuing the reaction for 8–10 hours, an appropriate amount of acetone was added to terminate the reaction, resulting in a yellow sol, which was neutralized with dilute hydrochloric acid. The obtained sol was separated, purified, and dried using ethanol precipitation to obtain plasticized modified PVA.

[0018] (2) Plasticized modified PVA is used as the sheath material and PBS is used as the core material for coaxial sheath-core spinning. The sheath material is melted and extruded by the first screw, then precisely metered by the first metering pump, and then enters the sheath channel of the dual-channel composite die for sheath-core spinning; the core material is melted and extruded by the second screw, then precisely metered by the second metering pump, and then enters the core channel of the dual-channel composite die for sheath-core spinning; after the two components pass through their respective channels, they are combined into fibers with a sheath-core structure on a spinneret with multiple spinneret holes, and then extruded through the spinneret to obtain multiple nascent spun fibers with a sheath-core structure.

[0019] (3) The nascent spun fibers enter the water tank for cooling and separation, undergo primary water bath stretching through the stretching roller, and secondary hot air stretching in the hot box. After stretching, each spun fiber is individually wound into a filament cake, thereby obtaining the eco-friendly biodegradable fiber described in this invention.

[0020] In the method described above, in step (1), the mass ratio of PVA, β-cyclodextrin and water is 1:3:12 to 1:4:16;

[0021] As described above, in step (1), the amount of sodium hydroxide aqueous solution added is 3 to 4 times the mass of β-cyclodextrin;

[0022] In the method described above, in step (1), the crosslinking agent is epichlorohydrin, and the molar ratio of epichlorohydrin to β-cyclodextrin is 1:2 to 1:5;

[0023] As described above, in step (2), the number of spinneret holes is 30 to 180.

[0024] As described above, in step (3), the stretching ratio of the first-stage water bath is 5 to 8 times, and the water bath temperature is 80 to 95°C.

[0025] As described above, in step (3), the stretching ratio of the secondary hot air is 1.1 to 1.7 times, and the hot air temperature is 120 to 150°C.

[0026] The beneficial effects of this invention are:

[0027] (1) Based on coaxial core-sheath spinning technology, PVA is coated onto the outside of PBS fibers. This not only simplifies the operation and produces composite fibers with excellent performance, but also effectively improves the controllability of PBS fiber degradation. PVA is stable, non-toxic, and can be decomposed into carbon dioxide and water under the action of microorganisms, making it a green and environmentally friendly polymer. PVA is water-soluble at water temperatures above 90℃, maintains stable performance under normal storage conditions, and exhibits excellent chemical and oil resistance. Even if PVA dissolves due to external conditions, the aqueous solution still exhibits excellent film-forming properties, forming a dense film structure that covers the outside of PBS fibers, preventing further degradation of PBS by water molecules and microorganisms.

[0028] (2) Since the melting point of PVA is higher than its decomposition temperature, it cannot be directly melt-spun, and existing processes often use wet spinning. In order to achieve coaxial melt spinning of PVA and PBS, PVA needs to be plasticized and modified. In this invention, β-cyclodextrin is selected as a plasticizer. It has a slightly conical hollow cylindrical three-dimensional ring structure with a hydrophilic outer side. Under the action of van der Waals forces, it can separate PVA segments, weaken the intermolecular forces, and significantly reduce the crystallinity of the polymer, thereby effectively improving the plasticity of PVA. In addition, the hydrophobic cavity of β-cyclodextrin can encapsulate the PBS segments, which greatly improves the compatibility between plasticized modified PVA and PBS during melt spinning. Attached Figure Description

[0029] Figure 1 This is a schematic cross-sectional view of an eco-friendly biodegradable fiber according to the present invention;

[0030] Figure 2 Infrared spectrum of plasticized modified PVA prepared according to the present invention. Detailed Implementation

[0031] The present invention will now be further described in conjunction with the accompanying drawings and relevant knowledge, and will be described clearly and completely. Obviously, the described applications are only some embodiments of the present invention, and not all embodiments.

[0032] An eco-friendly biodegradable fiber consists of a sheath and a core layer. The sheath covers the outside of the core layer. The core layer is composed of PBS, and the sheath is composed of plasticized modified PVA. The melting point of the sheath is 180–200℃, and the melting point of the core layer is 110–120℃. The sheath component accounts for 30–70% of the total composition, and the core component accounts for 70–30%. The melt index (190℃, 2.16kg) of both the sheath and core layer materials is 5–10g / 10min. The diameter is 0.05–0.07mm.

[0033] An eco-friendly biodegradable fiber preparation method involves first copolymerizing β-cyclodextrin with PVA to obtain plasticized modified PVA, then using it as the sheath material of the fiber and PBS as the core material, and preparing the eco-friendly biodegradable fiber by coaxial sheath-core spinning method.

[0034] The specific steps are as follows:

[0035] (1) PVA, β-cyclodextrin, and water were added to a three-necked flask and stirred to dissolve under water bath heating at 80–100°C. The temperature was then lowered to 50–70°C, and a 30% sodium hydroxide aqueous solution was slowly added dropwise while stirring continuously for 8–10 hours. After adding a crosslinking agent and continuing the reaction for 8–10 hours, an appropriate amount of acetone was added to terminate the reaction, resulting in a yellow sol, which was neutralized with dilute hydrochloric acid. The obtained sol was separated, purified, and dried using ethanol precipitation to obtain plasticized modified PVA.

[0036] (2) Plasticized modified PVA is used as the sheath material and PBS is used as the core material for coaxial sheath-core spinning. The sheath material is melted and extruded by the first screw, then precisely metered by the first metering pump, and then enters the sheath channel of the dual-channel composite die for sheath-core spinning; the core material is melted and extruded by the second screw, then precisely metered by the second metering pump, and then enters the core channel of the dual-channel composite die for sheath-core spinning; after the two components pass through their respective channels, they are combined into fibers with a sheath-core structure on a spinneret with multiple spinneret holes, and then extruded through the spinneret to obtain multiple nascent spun fibers with a sheath-core structure.

[0037] (3) The nascent spun fibers enter the water tank for cooling and separation, undergo primary water bath stretching through the stretching roller, and secondary hot air stretching in the hot box. After stretching, each spun fiber is individually wound into a filament cake, thereby obtaining the eco-friendly biodegradable fiber described in this invention.

[0038] In step (1), the mass ratio of PVA, β-cyclodextrin, and water is 1:3:12 to 1:4:16; the amount of sodium hydroxide aqueous solution added is 3 to 4 times the mass of β-cyclodextrin; the crosslinking agent is epichlorohydrin, and the molar ratio of epichlorohydrin to β-cyclodextrin is 1:2 to 1:5; the number of spinneret holes is 30 to 180; the first-stage water bath stretching ratio is 5 to 8 times, and the water bath temperature is 80 to 95°C; the second-stage hot air stretching ratio is 1.1 to 1.7 times, and the hot air temperature is 120 to 150°C.

[0039] This invention, based on coaxial core-sheath spinning technology, coats PVA onto the outside of PBS fibers. This not only simplifies the process and produces composite fibers with excellent performance, but also effectively improves the controllability of PBS fiber degradation. PVA is stable, non-toxic, and decomposes into carbon dioxide and water under microbial action, making it a green and environmentally friendly polymer. PVA exhibits water solubility at temperatures above 90°C, remains stable under normal storage conditions, and demonstrates excellent chemical and oil resistance. Even if PVA dissolves due to external conditions, the aqueous solution still exhibits excellent film-forming properties, forming a dense film structure covering the outside of the PBS fibers, preventing further degradation of PBS by water molecules and microorganisms. Because the melting point of PVA is higher than its decomposition temperature, it cannot be directly melt-spun; existing processes often employ wet spinning. To achieve coaxial melt spinning of PVA and PBS, PVA needs to be plasticized and modified. This invention uses β-cyclodextrin as a plasticizer. β-cyclodextrin has a slightly conical, hollow cylindrical three-dimensional ring structure with a hydrophilic outer layer. Under van der Waals forces, it can separate PVA segments, weakening intermolecular forces and significantly reducing polymer crystallinity, thereby effectively improving the plasticity of PVA. Furthermore, the hydrophobic cavity of β-cyclodextrin can encapsulate PBS segments, greatly improving the compatibility between plasticized PVA and PBS during melt spinning. This invention relates to an eco-friendly biodegradable fiber and its preparation method. Using biodegradable polyvinyl alcohol (PVA) and polybutylene succinate (PBS) as main raw materials, eco-friendly biodegradable fibers are prepared through coaxial core-sheath spinning. Since the core layer PBS fiber, as a biodegradable polyester, is susceptible to uncontrollable performance issues due to environmental factors, plasticized PVA is used as the sheath component, and melt spinning is used to prepare a controllable degradable composite fiber. Eco-friendly and biodegradable fibers have excellent performance and great development prospects in the field of soft furnishings.

[0040] Example 1

[0041] A method for preparing eco-friendly biodegradable fibers, the specific steps of which are as follows:

[0042] (1) PVA, β-cyclodextrin, and water were added to a three-necked flask in a mass ratio of 1:3:12 and stirred to dissolve under water bath heating at 80°C. The temperature was lowered to 50°C, and a 30% sodium hydroxide aqueous solution was slowly added dropwise, with the amount added being three times the mass of β-cyclodextrin. The mixture was stirred continuously for 10 hours. Epichlorohydrin, a crosslinking agent, was added at a molar ratio of 1:5 to β-cyclodextrin. The reaction was continued for 10 hours, and then an appropriate amount of acetone was added to terminate the reaction, resulting in a yellow sol. This sol was neutralized with dilute hydrochloric acid. The resulting sol was separated, purified, and dried using ethanol precipitation to obtain plasticized modified PVA.

[0043] (2) Plasticized modified PVA is used as the sheath material and PBS is used as the core material for coaxial sheath-core spinning. The sheath material is melted and extruded by the first screw, then precisely metered by the first metering pump, and then enters the sheath channel of the dual-channel composite die for sheath-core spinning; the core material is melted and extruded by the second screw, then precisely metered by the second metering pump, and then enters the core channel of the dual-channel composite die for sheath-core spinning; after the two components pass through their respective channels, they are combined into fibers with a sheath-core structure on a spinneret with multiple spinneret holes, and then extruded through the spinneret (with 180 spinneret holes) to obtain multiple nascent spun fibers with a sheath-core structure.

[0044] (3) The nascent spun fibers enter the water tank for cooling and separation, and are then subjected to a first-stage water bath stretching with a ratio of 5 times and a water bath temperature of 80°C. The fibers are then subjected to a second-stage hot air stretching in the hot box with a ratio of 1.1 times and a hot air temperature of 120°C. After stretching, each spun fiber is individually wound into a filament cake, thereby obtaining the eco-friendly biodegradable fiber described in this invention.

[0045] A cross-sectional schematic diagram of an eco-friendly biodegradable fiber was obtained. Figure 1 The fiber consists of a sheath 1 and a core 2, with the sheath 1 covering the outside of the core 2. The core component is PBS, and the sheath component is plasticized modified PVA. The sheath component accounts for 30% of the total composition, and the core component accounts for 70%. The melt index (190℃, 2.16kg) of both the sheath and core materials is 10g / 10min, and the diameter is 0.05mm.

[0046] The obtained plasticized modified PVA has the following infrared spectrum: Figure 2 As shown, for the PVA matrix, the position at 3192 cm⁻¹ is... -1 The absorption peak can be attributed to the -OH stretching vibration, 2947 cm⁻¹ -1 and 2909cm -1 The locations are the asymmetric and symmetric stretching vibrations of —CH2, 1389 cm⁻¹. -1 The location is attributed to the bending vibration of -CH2, 1262 cm. -1 The peak at 1179 cm⁻¹ corresponds to the C-C stretching vibration. The introduction of β-cyclodextrin resulted in a peak at 1179 cm⁻¹. -1 and 1093cm -1 The new peaks appear at the points, which are attributed to C-O-C stretching vibration and C-O-H bending vibration, respectively.

[0047] An eco-friendly biodegradable fiber was prepared, exhibiting excellent water resistance (specifically, after 24 hours of immersion in deionized water at 23±2℃, the fiber strength decreased by only 3.8%), excellent chemical resistance (specifically, after 24 hours of immersion in 5% hydrochloric acid and sodium hydroxide aqueous solutions at 23±2℃, the fiber strength decreased by 7.5% and 8.1%, respectively), and excellent controllable biodegradation performance (specifically, the degradation rate was 0% after washing with water at room temperature, 4.4% after washing with boiling water, and 82.3% after 45 days of boiling water washing).

[0048] Example 2

[0049] A method for preparing eco-friendly biodegradable fibers, the specific steps of which are as follows:

[0050] (1) PVA, β-cyclodextrin, and water were added to a three-necked flask in a mass ratio of 1:4:16 and stirred to dissolve under a water bath at 100°C. The temperature was lowered to 70°C, and a 30% sodium hydroxide aqueous solution was slowly added dropwise, with the amount added being 4 times the mass of β-cyclodextrin. The mixture was stirred continuously for 8 hours. Epichlorohydrin, a crosslinking agent, was added at a molar ratio of 1:2 to β-cyclodextrin. The reaction was continued for 8 hours, and then an appropriate amount of acetone was added to terminate the reaction, resulting in a yellow sol. This sol was neutralized with dilute hydrochloric acid. The resulting sol was separated, purified, and dried using ethanol precipitation to obtain plasticized modified PVA.

[0051] (2) Plasticized modified PVA is used as the sheath material and PBS is used as the core material for coaxial sheath-core spinning. The sheath material is melted and extruded by the first screw, then precisely metered by the first metering pump, and then enters the sheath channel of the dual-channel composite die for sheath-core spinning; the core material is melted and extruded by the second screw, then precisely metered by the second metering pump, and then enters the core channel of the dual-channel composite die for sheath-core spinning; after the two components pass through their respective channels, they are combined into fibers with a sheath-core structure on a spinneret with multiple spinneret holes, and then extruded through the spinneret (with 30 spinneret holes) to obtain multiple nascent spun fibers with a sheath-core structure.

[0052] (3) The nascent spun fibers enter the water tank for cooling and separation, and are then subjected to a first-stage water bath stretching with a ratio of 8 times and a water bath temperature of 95°C. The fibers are then subjected to a second-stage hot air stretching in the hot box with a ratio of 1.7 times and a hot air temperature of 150°C. After stretching, each spun fiber is individually wound into a filament cake, thereby obtaining the eco-friendly biodegradable fiber described in this invention.

[0053] An eco-friendly biodegradable fiber was prepared, with the dermis component accounting for 70% of the total composition and the core component accounting for 30% of the total composition. The melt index (190℃, 2.16kg) of the dermis and core materials was 5g / 10min, and the diameter was 0.07mm.

[0054] An eco-friendly biodegradable fiber was prepared, exhibiting excellent water resistance (specifically, after 24 hours of immersion in deionized water at 23±2℃, the fiber strength decreased by only 4.2%), excellent chemical resistance (specifically, after 24 hours of immersion in 5% hydrochloric acid and sodium hydroxide aqueous solutions at 23±2℃, the fiber strength decreased by 6.2% and 7.5%, respectively), and excellent controllable biodegradation performance (specifically, the degradation rate was 0% after washing with water at room temperature, 6.1% after washing with boiling water, and 79.8% after 45 days of boiling water washing).

[0055] Example 3

[0056] A method for preparing eco-friendly biodegradable fibers, the specific steps of which are as follows:

[0057] (1) PVA, β-cyclodextrin, and water were added to a three-necked flask in a mass ratio of 1:3:14 and stirred to dissolve under a water bath at 90°C. The temperature was lowered to 60°C, and a 30% sodium hydroxide aqueous solution was slowly added dropwise, with the amount added being 3.5 times the mass of β-cyclodextrin. The mixture was stirred continuously for 9 hours. Epichlorohydrin, a crosslinking agent, was added at a molar ratio of 1:4 to β-cyclodextrin. The reaction was continued for 9 hours, and then an appropriate amount of acetone was added to terminate the reaction, resulting in a yellow sol. This sol was neutralized with dilute hydrochloric acid. The resulting sol was separated, purified, and dried using ethanol precipitation to obtain plasticized modified PVA.

[0058] (2) Plasticized modified PVA is used as the sheath material and PBS is used as the core material for coaxial sheath-core spinning. The sheath material is melted and extruded by the first screw, then precisely metered by the first metering pump, and then enters the sheath channel of the dual-channel composite die for sheath-core spinning; the core material is melted and extruded by the second screw, then precisely metered by the second metering pump, and then enters the core channel of the dual-channel composite die for sheath-core spinning; after the two components pass through their respective channels, they are combined into fibers with a sheath-core structure on a spinneret with multiple spinneret holes, and then extruded through the spinneret (with 100 spinneret holes) to obtain multiple nascent spun fibers with a sheath-core structure.

[0059] (3) The nascent spun fibers enter the water tank for cooling and separation, and are then subjected to a first-stage water bath stretching with a ratio of 7 times and a water bath temperature of 90°C. The fibers are then subjected to a second-stage hot air stretching in the hot box with a ratio of 1.5 times and a hot air temperature of 140°C. After stretching, each spun fiber is individually wound into a filament cake, thereby obtaining the eco-friendly biodegradable fiber described in this invention.

[0060] An eco-friendly biodegradable fiber was prepared, with the pelvis component accounting for 50% of the total composition and the core component accounting for 50% of the total composition. The melt index (190℃, 2.16kg) of the pelvis and core materials was 7g / 10min, and the diameter was 0.06mm.

[0061] An eco-friendly biodegradable fiber was prepared, exhibiting excellent water resistance (specifically, the fiber strength decreased by only 5.5% after being placed in deionized water at 23±2℃ for 24 hours); excellent chemical resistance (specifically, the fiber strength decreased by 8.8% and 9.5% respectively after being placed in hydrochloric acid and sodium hydroxide aqueous solutions at 23±2℃ for 24 hours); and excellent controllable biodegradation performance (specifically, the degradation rate was 0% after washing with water at room temperature, 5.3% after washing with boiling water, and 85.6% after 45 days of boiling water washing).

[0062] Comparative Example 1

[0063] A method for preparing plasticized modified PVA / PBS blended fibers, the specific steps of which are as follows:

[0064] (1) PVA, β-cyclodextrin, and water were added to a three-necked flask in a mass ratio of 1:4:13 and stirred to dissolve under a water bath at 90°C. The temperature was then lowered to 60°C, and a 30% sodium hydroxide aqueous solution was slowly added dropwise, with the amount added being four times the mass of β-cyclodextrin. The mixture was stirred continuously for 9 hours. Epichlorohydrin, a crosslinking agent, was added at a molar ratio of 1:4 to β-cyclodextrin. The reaction was continued for 8 hours, and then an appropriate amount of acetone was added to terminate the reaction, resulting in a yellow sol. This sol was neutralized with dilute hydrochloric acid. The resulting sol was separated, purified, and dried using ethanol precipitation to obtain plasticized modified PVA.

[0065] (2) Plasticized modified PVA and PBS are blended and melt-spun at a mass ratio of 3:7. The fibers are then compounded on a spinneret with multiple spinneret holes and extruded through the spinneret (with 120 spinneret holes) to obtain multiple nascent spun fibers.

[0066] (3) The nascent spun fibers enter the water tank for cooling and separation, and are then subjected to a first-stage water bath stretching with a ratio of 7 times and a water bath temperature of 95°C. The fibers are then subjected to a second-stage hot air stretching in the hot box with a ratio of 1.6 times and a hot air temperature of 130°C. After stretching, each spun fiber is individually wound into a filament cake, thereby obtaining plasticized modified PVA / PBS blended fibers.

[0067] Comparing Example 3 with Comparative Example 1, the plasticized modified PVA / PBS blend fiber prepared in Comparative Example 1 exhibited poor water resistance, specifically: after being placed in deionized water at 23±2℃ for 24 hours, the fiber strength decreased by 35.5%; it also showed poor chemical resistance, specifically: after being placed in hydrochloric acid and sodium hydroxide aqueous solutions at 23±2℃ for 24 hours, the fiber strength decreased by 68.9% and 69.9%, respectively; and it lacked controllable biodegradability, specifically: the degradation rate was 24.6% after washing with water at room temperature, 58.1% after washing with boiling water, and 97.6% after 45 days of boiling water washing. This is because the plasticized modified PVA / PBS blend fiber lacks a core-sheath structure, and the addition of plasticized modified PVA cannot improve the controllable degradation of the PBS fiber.

[0068] Comparative Example 2

[0069] A method for preparing PVA / PBS core-sheath structured fibers, the specific steps of which are as follows:

[0070] Pure PVA is used as the sheath material and PBS as the core material for coaxial sheath-core spinning. The sheath material is melted and extruded by the first screw, then precisely metered by the first metering pump, and then enters the sheath channel of the dual-channel composite die for sheath-core spinning. The core material is melted and extruded by the second screw, then precisely metered by the second metering pump, and then enters the core channel of the dual-channel composite die for sheath-core spinning. After passing through their respective channels, the two components are combined on a spinneret with multiple spinneret holes to form fibers with a sheath-core structure.

[0071] Comparing Example 3 with Comparative Example 2, Comparative Example 2 could not prepare complete PVA / PBS core-sheath structure fibers. This is because the melting point of PVA is higher than its decomposition temperature, and it is easy to decompose during processing. Therefore, it cannot be directly melt-spun and PVA must be plasticized and modified.

[0072] Comparative Example 3

[0073] A method for preparing plasticized modified PVA / PBS core-sheath structured fibers, the specific steps of which are as follows:

[0074] (1) PVA and β-cyclodextrin were blended and melted at a mass ratio of 9:1 to obtain plasticized modified PVA masterbatch.

[0075] (2) Plasticized modified PVA masterbatch is used as the sheath material and PBS is used as the core material for coaxial sheath-core spinning. The sheath material is melted and extruded by the first screw, then precisely metered by the first metering pump, and then enters the sheath channel of the dual-channel composite die for sheath-core spinning; the core material is melted and extruded by the second screw, then precisely metered by the second metering pump, and then enters the core channel of the dual-channel composite die for sheath-core spinning; after the two components pass through their respective channels, they are combined into fibers with a sheath-core structure on a spinneret with multiple spinneret holes, and then extruded through the spinneret (with 100 spinneret holes) to obtain multiple nascent spun fibers with a sheath-core structure.

[0076] (3) The nascent spun fibers enter the water tank for cooling and separation, and are then subjected to a first-stage water bath stretching with a ratio of 7 times and a water bath temperature of 90°C. The fibers are then subjected to a second-stage hot air stretching in the hot box with a ratio of 1.5 times and a hot air temperature of 140°C. After stretching, each spun fiber is individually wound into a filament cake, thereby obtaining plasticized modified PVA / PBS core-sheath structure fiber.

[0077] Comparing Example 3 with Comparative Example 3, the plasticized modified PVA / PBS core-sheath structure fiber prepared in Comparative Example 3 exhibited moderate water resistance (specifically, the fiber strength decreased by 10.2% after 24 hours in deionized water at 23±2℃); poor chemical resistance (specifically, the fiber strength decreased by 45.7% and 59.7% after 24 hours in hydrochloric acid and sodium hydroxide aqueous solutions at 23±2℃, respectively); and moderate biodegradability (specifically, the degradation rate was 6.6% after washing with water at room temperature, 32.3% after washing with boiling water, and 91.1% after 45 days of boiling water washing). This is because during the preparation of the plasticized modified PVA / PBS core-sheath structure fiber, β-cyclodextrin was added to PVA in a blending manner to obtain modified masterbatch, resulting in a significantly worse plasticizing effect compared to modified PVA prepared by copolymerization, thus failing to effectively improve the degradation controllability of the PBS fiber.

[0078] The technical principles of the present invention have been described above with reference to specific embodiments, which are merely preferred embodiments of the present invention. The scope of protection of the present invention is not limited to the above embodiments; all technical solutions falling within the scope of the present invention's concept are within its protection scope. Those skilled in the art can conceive of other specific embodiments of the present invention without creative effort, and these embodiments will all fall within the protection scope of the present invention.

Claims

1. An eco-friendly biodegradable fiber, characterized in that, Composed of a skin layer and a core layer, with the skin layer covering the outside of the core layer, the core layer component is PBS, and the skin layer component is plasticized modified PVA. The melting point of the skin layer is 180~200℃, and the melting point of the core layer is 110~120℃. The preparation process of the plasticized modified PVA is as follows: PVA, β-cyclodextrin, and water are added to a three-necked flask and stirred and dissolved under water bath heating at 80~100℃; the temperature is lowered to 50~70℃, and a 30% sodium hydroxide aqueous solution is slowly added dropwise while stirring continuously for 8~10 hours; after adding a crosslinking agent and continuing the reaction for 8~10 hours, an appropriate amount of acetone is added to terminate the reaction, resulting in a yellow sol. The sol is neutralized with dilute hydrochloric acid, and the obtained sol is separated, purified, and dried by ethanol precipitation to obtain the plasticized modified PVA.

2. The eco-friendly biodegradable fiber as described in claim 1, characterized in that, The cortex component accounts for 30-70% of the total composition, with the core component making up the remainder.

3. The eco-friendly biodegradable fiber as described in claim 2, characterized in that, The melt flow index (190℃, 2.16kg) of the skin and core materials is 5~10 g / 10min.

4. The eco-friendly biodegradable fiber as described in claim 3, characterized in that, The diameter of the fiber is 0.05~0.07mm.

5. A method for preparing eco-friendly biodegradable fiber, characterized in that, First, plasticized modified PVA is prepared, and then it is used as the sheath material of the fiber, while PBS is used as the core material. Eco-friendly biodegradable fibers are prepared by coaxial sheath-core spinning. The preparation process of plasticized modified PVA is as follows: PVA, β-cyclodextrin and water are added to a three-necked flask and stirred to dissolve under water bath heating at 80~100℃; the temperature is lowered to 50~70℃, and a 30% sodium hydroxide aqueous solution is slowly added dropwise while stirring continuously for 8~10 hours; after adding a crosslinking agent and continuing the reaction for 8~10 hours, an appropriate amount of acetone is added to terminate the reaction, resulting in a yellow sol. The sol is neutralized with dilute hydrochloric acid, and the obtained sol is separated, purified and dried by ethanol precipitation to obtain plasticized modified PVA.

6. The method for preparing an eco-friendly biodegradable fiber as described in claim 5, characterized in that, Plasticized modified PVA is used as the skin layer material and PBS is used as the core layer material for coaxial skin-core spinning. Specifically, the skin layer material is melted and extruded by the first screw, then precisely metered by the first metering pump, and then enters the skin layer channel of the dual-channel composite die for skin-core spinning; the core layer material is melted and extruded by the second screw, then precisely metered by the second metering pump, and then enters the core layer channel of the dual-channel composite die for skin-core spinning. After passing through their respective channels, the two components are combined into fibers with a core-sheath structure on a spinneret with multiple spinneret holes. The fibers are then extruded through the spinneret to obtain multiple nascent spun fibers with a core-sheath structure.

7. The method for preparing an eco-friendly biodegradable fiber as described in claim 6, characterized in that, The nascent spun fibers enter a water tank for cooling and separation, undergo primary water bath stretching via a stretching roller, and secondary hot air stretching in a hot box. After stretching, each spun fiber is individually wound into a filament cake, thus obtaining eco-friendly biodegradable fibers.

8. The method for preparing an eco-friendly biodegradable fiber as described in claim 7, characterized in that, The mass ratio of PVA, β-cyclodextrin and water is (1:3:12) to (1:4:16).

9. The method for preparing an eco-friendly biodegradable fiber as described in claim 8, characterized in that, The amount of sodium hydroxide aqueous solution added is 3 to 4 times the mass of β-cyclodextrin, and the crosslinking agent is epichlorohydrin, with a molar ratio of 1:2 to 1:5 with β-cyclodextrin.

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