Degradable fiber and preparation method thereof
By using core-sheath co-extrusion and double-twist texturing composite technology, degradable masterbatch is added to the core and sheath of the fiber to prepare reliable and controllable degradable fibers. This solves the problems of fiber degradation uniformity and performance loss in existing technologies, and achieves international certification and performance retention.
Patent Information
- Application Number
- CN202610007084.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2025-12-23
- Filing Date
- 2026-01-05
- Publication Date
- 2026-02-17
AI Technical Summary
Existing chemical fiber modification schemes suffer from poor degradation uniformity and controllability, significant fiber performance loss, and low certification pass rates, making it difficult to achieve reliable and controllable biodegradability and performance retention without altering mature chemical fiber production processes and equipment.
By employing core-sheath co-extrusion technology, degradable masterbatch is added to both the core and sheath layers of the fiber to prepare twisted core-sheath fibers, including high-melting-point polyester and low-melting-point polymers. These fibers are then combined through double-twist texturing to form biodegradable fibers, ensuring that their mechanical properties remain unaffected.
It achieves controllable biodegradability of fibers without changing existing production processes, enabling them to pass international certification standards, while maintaining their mechanical properties and processability essentially unchanged.
Smart Images
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Abstract
Description
[0001] This invention claims priority to Chinese Patent Application No. 202511954559.2, filed with the China National Intellectual Property Administration on December 23, 2025, entitled "A biodegradable fiber and a method for preparing the same", the entire contents of which are incorporated herein by reference. Technical Field
[0002] This invention relates to the field of fiber preparation technology, and in particular to a biodegradable fiber and its preparation method. Background Technology
[0003] Developing environmentally friendly and biodegradable fiber materials has become an inevitable trend and research focus for the sustainable development of the chemical fiber industry.
[0004] Currently, technological development in this field mainly focuses on two directions: The first is the development of novel bio-based biodegradable polymer materials and their spinning into fibers, such as polylactic acid (PLA), polyhydroxyalkanoates (PHA), and polybutylene adipate / terephthalate (PBAT). Although these materials have good biodegradability, their large-scale application is often limited by high raw material costs, complex synthesis processes, and shortcomings in mechanical properties, thermal stability, or spinnability compared to traditional synthetic fibers, making it difficult to fully replace existing products in a short period of time.
[0005] The second category involves modifying existing large-scale-produced traditional chemical fibers, which is currently the more economical and feasible approach. Common existing solutions include blending and spinning or surface treatment. However, these existing solutions have significant technical problems: poor degradation uniformity and controllability: during simple mechanical blending, the degradation components are unevenly dispersed in the fiber matrix, easily leading to uncontrollable structural collapse during degradation, premature failure of mechanical properties, and incomplete degradation products, making it impossible to ensure that the final product passes rigorous certification testing. Significant loss of fiber intrinsic properties: to achieve degradability, a high proportion of degradation components is often required, which usually severely sacrifices the original excellent mechanical properties (such as strength, modulus, and abrasion resistance) and processability of the fiber, resulting in limited product applications. Lack of guaranteed certification pass rate: although many modification solutions show some degradation effect under laboratory conditions, due to unclear degradation mechanisms and immature processes, the final products cannot meet internationally recognized stringent testing standards (such as ISO 14855, ASTM D6400), making it difficult to obtain certification from authoritative institutions, market access, and consumer trust.
[0006] Therefore, there is an urgent need in this field for an innovative technical solution that can effectively transform traditional non-degradable chemical fibers into fibers with reliable and controllable biodegradability without significantly changing existing mature chemical fiber production processes and equipment, while retaining their original excellent properties to the maximum extent and ensuring that their degradation performance can pass the testing and certification of international authoritative standards. Summary of the Invention
[0007] In view of this, the object of the present invention is to provide a biodegradable fiber and a method for preparing the same. The preparation method provided by the present invention can impart biodegradability to the fiber without changing its mechanical properties.
[0008] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for preparing biodegradable fibers, comprising the following steps: After melting the raw materials for preparing the sheath and the raw materials for preparing the core, they are co-extruded through a sheath-core composite process. The resulting nascent fibers are then cooled, oiled, and twisted sequentially to obtain pre-drawn yarn. The pre-drawn yarn is subjected to double-twist texturing composite to obtain the biodegradable fiber; The raw materials for preparing the core layer include the following components by mass percentage: 98-99% high-melting-point polyester and 1-2% first degradation masterbatch, wherein the high-melting-point polyester has a melting point of 250-260°C and the first degradation masterbatch is ASMD®-PET 6000; The raw materials for preparing the skin layer include the following components by mass percentage: 98-99% low-melting-point polymer and 1-2% second degradation masterbatch; the low-melting-point polymer is low-melting-point polyester or polypropylene, and the melting point of the low-melting-point polymer is 150-210℃. When the low-melting-point polymer is low-melting-point polyester, the second degradation masterbatch is ASMD®-PET 6000; When the low-melting-point polymer is polypropylene, the second degradation masterbatch is ASMD®-PP 7000.
[0009] Preferably, in the raw materials for preparing the biodegradable fiber, the raw materials for preparing the sheath layer account for 20-40% by mass, and the raw materials for preparing the core layer account for 80-60% by mass.
[0010] Preferably, the high-melting-point polyester is further dried before use so that the moisture content of the dried high-melting-point polyester is less than 30 ppm.
[0011] Preferably, the low-melting-point polyester is further dried before use so that the moisture content of the dried low-melting-point polyester is less than 50 ppm.
[0012] Preferably, the melting temperature of the raw material for preparing the skin layer is 180~230℃.
[0013] Preferably, the melting temperature of the raw materials for preparing the core layer is 250~300℃.
[0014] Preferably, the total fineness of the pre-drawn yarn is 133~594 dtex, and the fineness of the single filament is 3.2~7.2 dtex.
[0015] Preferably, before the pre-drawn yarn undergoes double-twist texturing, the process further includes: sequentially performing a first preheating and a second preheating on the pre-drawn yarn; the temperatures of the first preheating and the second preheating are independently 120~150℃.
[0016] Preferably, the conditions for the double twisted texturing composite include: a draw ratio of 1.6 to 1.8 times and a texturing D / Y ratio of 1.5 to 3.
[0017] The present invention also provides a biodegradable fiber prepared by the preparation method described above, wherein the biodegradable fiber is a twisted core-sheath fiber, comprising a sheath layer and a core layer; the total fineness of the biodegradable fiber is 167~660 dtex, and the fineness of the single filament is 2~4 dtex.
[0018] This invention provides a method for preparing biodegradable fibers.
[0019] The preparation method of this invention adds degradable masterbatch to the raw materials for both the core layer and the sheath layer. This degradable masterbatch imparts biodegradability to the fiber without adversely affecting its mechanical or other properties. Data from the examples show that, under the ASTM D5511 standard, the biodegradable fiber provided by this invention achieves a 45-day anaerobic biodegradation rate of 7.55%. Attached Figure Description
[0020] Figure 1 Image of an anaerobic digestion sludge sample mixed with domestic waste; Figure 2 Microscopic images of the biodegradable fibers obtained in Example 1 before and after 45 days of culture (exposed and unexposed); Figure 3 The graph shows the net biogas production of the biodegradable fiber (test sample) and the positive control (reference material - cellulose) obtained in Example 1. Figure 4 This represents the percentage of biodegradation in the positive control (reference material). Figure 5 The percentage of biodegradable fiber obtained in Example 1 is the percentage of biodegradable fiber. Detailed Implementation
[0021] This invention provides a method for preparing biodegradable fibers, comprising the following steps: After melting the raw materials for preparing the sheath and the raw materials for preparing the core, they are co-extruded through a sheath-core composite process. The resulting nascent fibers are then cooled, oiled, and twisted sequentially to obtain pre-drawn yarn. The pre-drawn yarn is subjected to double-twist texturing composite to obtain the biodegradable fiber; The raw materials for preparing the core layer include the following components by mass percentage: 98-99% high-melting-point polyester and 1-2% first degradation masterbatch, wherein the high-melting-point polyester has a melting point of 250-260°C and the first degradation masterbatch is ASMD®-PET 6000; The raw materials for preparing the skin layer include the following components by mass percentage: 98-99% low-melting-point polymer and 1-2% second degradation masterbatch; the low-melting-point polymer is low-melting-point polyester or polypropylene, and the melting point of the low-melting-point polymer is 150-210℃. When the low-melting-point polymer is low-melting-point polyester, the second degradation masterbatch is ASMD®-PET 6000; When the low-melting-point polymer is polypropylene, the second degradation masterbatch is ASMD®-PP 7000.
[0022] Unless otherwise specified, all raw materials used in this invention are commercially available products.
[0023] In this invention, the raw materials for preparing the sheath and the raw materials for preparing the core are melted separately and then co-extruded through a sheath-core composite process. The resulting nascent fibers are then cooled, oiled, and twisted sequentially to obtain pre-drawn yarn.
[0024] In this invention, the raw materials for preparing the core layer include the following components by mass percentage: 98-99% high-melting-point polyester and 1-2% first degradation masterbatch. The high-melting-point polyester has a melting point of 250-260°C, preferably 250°C, 255°C, or 260°C. Specifically, by mass percentage, the raw materials for preparing the core layer preferably include 98%, 98.5%, or 99% high-melting-point polyester; and 1%, 1.5%, or 2% first degradation masterbatch. In this invention, the first degradation masterbatch is ASMD®-PET 6000 (full name ASMD®-PET6000 (Anaerobic + Sea) Biodegradable Masterbatch).
[0025] In this invention, the raw materials for preparing the skin layer comprise the following components by mass percentage: 98-99% low-melting-point polymer and 1-2% second degradation masterbatch. Specifically, by mass percentage, the raw materials for preparing the skin layer preferably comprise 98%, 98.5%, or 99% low-melting-point polymer; and 1%, 1.5%, or 2% second degradation masterbatch. In this invention, the low-melting-point polymer is low-melting-point polyester or polypropylene, and the melting point of the low-melting-point polymer is 150-210°C, specifically preferably 150°C, 155°C, 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, 190°C, 195°C, 200°C, 205°C, or 210°C. In this invention, when the low-melting-point polymer is low-melting-point polyester, the second degradation masterbatch is ASMD®-PET 6000 (full name ASMD®-PET6000 (Anaerobic + Sea) Biodegradable Masterbatch); when the low-melting-point plastic is polypropylene, the second degradation masterbatch is ASMD®-PP 7000 (full name ASMD®-PP7000 (Anaerobic + Sea) Biodegradable Masterbatch). In this invention, the low-melting-point polymer is low-melting-point polyester (PET), which can meet the texturing requirements.
[0026] In this invention, the raw materials for preparing the biodegradable fiber preferably account for 20-40% by mass, specifically 20%, 25%, 30%, 35% or 40%; the raw materials for preparing the core layer preferably account for 80-60% by mass, specifically 80%, 75%, 70%, 65% or 60%.
[0027] In this invention, the high melting point polyester is preferably dried (referred to as first drying) before use. This invention does not specifically limit the parameters of the first drying, as long as the moisture content of the dried high melting point polyester is less than 30 ppm.
[0028] In this invention, the low-melting-point polyester is preferably further dried (referred to as second drying) before use. The temperature of the second drying is preferably 80~100℃, specifically 80℃, 90℃ or 100℃; the time is preferably 8~12h, specifically 8h, 9h, 10h, 11h or 12h, so that the moisture content of the dried low-melting-point polyester is less than 50ppm.
[0029] In this invention, the first and second degradation masterbatches preferably undergo drying (referred to as third drying) before use. In this invention, the third drying temperature is preferably 80°C, and the drying time is preferably 2-3 hours, preferably carried out in an oven.
[0030] In this invention, controlling the moisture content of high-melting-point polyester and low-melting-point polyester before use, and drying the degradation masterbatch, can ensure the spinning process and avoid filament drift.
[0031] In this invention, the melting temperature of the raw material for preparing the skin layer is preferably 180~230℃, specifically preferably 180℃, 190℃, 200℃, 210℃, 220℃ or 230℃; the melting temperature of the raw material for preparing the core layer is preferably 250~300℃, specifically preferably 250℃, 260℃, 270℃, 280℃, 290℃ or 300℃.
[0032] In this invention, the core-sheath co-extrusion is preferably carried out in a twin-screw composite spinning device. Preferably, the twin-screw composite spinning device is equipped with a core-sheath spinning dual-channel composite die and a spinneret, the specifications of which need to match the fineness of the pre-drawn yarn.
[0033] In this invention, the preferred process of melting the raw materials for the skin layer and the raw materials for the core layer separately, followed by co-extrusion of the skin-core composite material, includes: The raw materials for preparing the skin layer are melted and extruded by the first screw, then precisely metered by the first metering pump and enter the skin layer channel of the skin-core spinning assembly; The raw materials for the core layer are melted and extruded by the second screw, then precisely metered by the second metering pump and enter the core layer channel of the core-sheath spinning assembly; The cortex component output from the cortex channel and the core component output from the core channel are combined on a spinneret with multiple spinneret holes to form a fiber with a cortex-core structure. The fiber with a cortex-core structure is extruded through the spinneret to obtain multiple nascent fibers with a cortex-core structure.
[0034] In this invention, the cooling oiling is preferably performed in the side-blowing cooling window. This invention does not specifically limit the operation of the cooling oiling; any operation well-known to those skilled in the art can be used.
[0035] The present invention does not specifically limit the plying operation, as long as the pre-drawn yarn with the target fineness can be obtained.
[0036] After the stranding, the present invention preferably further includes tension adjustment and winding. In this invention, the tension adjustment is preferably performed on the guide coil, and the parameters for the tension adjustment are not specifically limited; operations familiar to those skilled in the art can be used. In this invention, the winding is preferably performed in a high-speed winding device.
[0037] In this invention, the total fineness of the pre-drawn yarn is preferably 133~594 dtex, and the fineness of the single filament is preferably 3.2~7.2 dtex.
[0038] After obtaining the pre-drawn yarn, the present invention performs double-twist texturing composite on the pre-drawn yarn to obtain the biodegradable fiber.
[0039] Before the pre-drawn yarn undergoes double-twist texturing, the present invention preferably further includes: subjecting the pre-drawn yarn to a first preheating and a second preheating sequentially. In the present invention, the temperature of the first preheating is preferably 120~150℃, specifically preferably 120℃, 130℃, 140℃, or 150℃. In the present invention, the first preheating is preferably performed in a first heating chamber. In the present invention, the temperature of the second preheating is preferably 120~150℃, specifically preferably 120℃, 130℃, 140℃, or 150℃. In the present invention, the second preheating is preferably performed in a second heating chamber. In the present invention, the first and second preheating can promote the deformation and shaping of the pre-drawn yarn.
[0040] In this invention, the conditions for the double-twist texturing composite include: the draw ratio is preferably 1.6 to 1.8 times, specifically preferably 1.6 times, 1.7 times, or 1.8 times; the texturing D / Y ratio is preferably 1.5 to 3, specifically preferably 1.5, 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, or 3.
[0041] In this invention, the double twist texturing composite is preferably performed on a double twist texturing machine.
[0042] In this invention, the total fineness of the biodegradable fiber is preferably 167~660 dtex, and the fineness of the single filament is preferably 2~4 dtex.
[0043] The present invention also provides a biodegradable fiber prepared by the preparation method described above, wherein the biodegradable fiber is a twisted core-sheath fiber, comprising a sheath layer and a core layer; the total fineness of the biodegradable fiber is 167~660 dtex, and the fineness of the single filament is 2~4 dtex.
[0044] The following detailed description of the biodegradable fiber and its preparation method provided by the present invention, with reference to the embodiments, should not be construed as limiting the scope of protection of the present invention.
[0045] Example 1 Biodegradable fibers are produced on a twin-screw composite spinning machine and a double-twist texturing machine. The entire production process is as follows: 1. Preparation of raw materials for the leather layer: Dry low-melting-point PET (melting point of 200℃) at 100℃ for 10h until the water content is less than 50ppm; dry ASMD®-PET 6000 at 80℃ for 2h; mix the dried low-melting-point polyester and ASMD®-PET 6000 at a mass ratio of 98:2.
[0046] 2. Preparation of raw materials for core layer preparation: Dry high melting point polyester (melting point of 260℃) to make the water content less than 30ppm; dry ASMD®-PET 6000 at 80℃ for 2h; and mix the dried high melting point polyester and ASMD®-PET 6000 at a mass ratio of 98:2.
[0047] 3. Assembly and preparation of composite components: On the twin-screw composite spinning equipment, install the core-sheath spinning dual-channel composite die head, and select a spinneret with a certain number of holes (66 holes) according to the specifications of the yarn to be produced and the final pre-drawn yarn single filament fineness (dpf) to be met.
[0048] 4. The raw materials for the sheath layer are melted and extruded by the first screw at 220℃, then precisely metered by the first metering pump and enter the sheath channel of the sheath-core spinning assembly. The raw materials for the core layer are melted and extruded by the second screw at 290℃, then precisely metered by the second metering pump and enter the core channel of the sheath-core spinning assembly. After passing through their respective channels, the two raw materials are combined into fibers with a sheath-core structure on a spinneret with 66 spinneret holes. These fibers are then extruded through the spinneret to obtain multiple nascent fibers with a sheath-core structure. The resulting nascent fibers enter a side-blown cooling window for cooling and oiling, then enter the channel for plying. After tension adjustment by a guide disc, they are wound by a high-speed winding device to produce POY sheath-core composite pre-drawn yarn. The mass ratio of the raw materials for the sheath layer to the raw materials for the core layer is 25:75. The total fineness of the POY sheath-core composite pre-drawn yarn is 336 dtex, and the fineness of each filament is 5.09 dtex.
[0049] 5. After a certain period of equilibration, the POY core-sheath composite pre-drawn yarn is sent to a double-twist texturing machine. The two POY core-sheath composite pre-drawn yarns are preheated in the first heating box (temperature set at 150℃) and the second heating box (temperature set at 120℃) of the double-twist texturing machine, respectively. After the first preheating, the yarn is then double-twist texturing composite to form a biodegradable fiber with a total fineness of 420 dtex and a single filament fineness of 3.18 dtex. The conditions for double-twist texturing composite include: a draw ratio of 1.6 and a texturing D / Y ratio of 1.9.
[0050] The performance of the obtained biodegradable fibers was tested, and the results are shown in Table 1.
[0051] Table 1. Performance test results of the biodegradable fibers obtained in Example 1
[0052] Comparative Example 1 The difference from Example 1 is that no degradation masterbatch is added to the core layer and the skin layer, while all other operations are the same as in Example 1.
[0053] The obtained fibers were subjected to performance tests, and the results are shown in Table 2.
[0054] Table 2 shows the performance test results of the fibers obtained in Comparative Example 1.
[0055] The biodegradable fibers obtained in Example 1 were tested according to ASTM D5511. This test method involves determining the extent and rate of anaerobic biodegradation of the plastic material under high-solids anaerobic conditions. The test material was exposed to methanogenic inoculum produced by an anaerobic digester operating only on pretreated municipal solid waste. Anaerobic decomposition was carried out under high solids content (total solids exceeding 30%) and static, unmixed conditions. This test method aims to determine the percentage of carbon in a sample converted to gaseous carbon under conditions found in high-solids anaerobic digesters treating municipal solid waste.
[0056] (1) Collection and conditioning of inoculum Anaerobic digestion sludge mixed with domestic waste (such as...) Figure 1 (Shown) From Chembur (Mumbai). To allow the sludge to adapt and stabilize during a short post-fermentation process at 53°C, the sludge was pre-incubated at 53°C (for one week). This means that the concentrated inoculum was not fed but was allowed to undergo post-fermentation of the residue of previously added organic matter, thereby degrading large particles that are easily biodegradable and reducing the biogas background level of the inoculum itself.
[0057] (2) Characteristics of inoculum The pH value, total Kjeldahl nitrogen, dry solids percentage and volatile solids of the anaerobic digestion sludge samples were analyzed, as shown in Table 3.
[0058] Table 3 Test results of anaerobic digestion sludge samples
[0059] (3) Method Inoculum culture medium: Take a sufficient amount of inoculum (approximately 15 kg) from the post-fermentation container and mix it thoroughly by hand to obtain a homogeneous culture medium. Perform three replicate tests on the blank (inoculum only), positive control (reference material), (thin-layer chromatography cellulose), and the test material to be evaluated.
[0060] In a small container, manually mix 1000 g of wet weight (at least 20% dry solids) of inoculum for 2 to 3 minutes with 15 to 100 g of the test substance or control with volatile solids. For three blanks containing only inoculum, manually mix 1000 g of the same inoculum in a small container for 2 to 3 minutes with the same strength as the other containers containing the test substance or control. Accurately determine the weight of inoculum and test substance added to each individual Erlenmeyer flask. Add the mixture to a 2 L wide-mouth Erlenmeyer flask, spread it gently, and compact the material evenly to a uniform density.
[0061] After placing the conical flask in the incubator, connect it to the gas collection device. Incubate the flask under high temperature conditions in darkness or diffuse light at 52°C (±2°C). The incubation period should continue until no net gas is produced in the reactors of the positive control (reference material) and the test material for at least five days. The pH of the water used to measure biogas production is controlled below 2 by adding HCl. The presence of gas in the gas collector of the positive control (reference material) indicates that the inoculum is feasible, and gas displacement is observed in both the positive control (reference material) and the test sample. ASTM D5511 specifies that for the test to be valid, the positive control (reference material) must reach 70% within 30 days, with a deviation between replicates less than 20% of the mean. The positive control (reference material) showed 70.35% on day 27, with an average difference between replicates less than 20%. Gas displacement observed after 45 days is shown in Table 4.
[0062] Table 4. Biogas volume released during 45 days of biodegradation.
[0063] Bacterial colonization was observed in certain locations under a microscope, and the results were as follows: Figure 2 As shown, A and B represent the unexposed biodegradable fibers of Example 1, with A before the biodegradation test and B after the biodegradation test; C and D represent the exposed biodegradable fibers of Example 1, with C before the biodegradation test and D after the biodegradation test. Figure 2 It can be seen that the biodegradation process has begun.
[0064] The percentage of biodegradation for the positive control (reference material) and test samples was calculated by subtracting the carbon dioxide and methane releases from the blank samples at the end of the 45-day test from the cumulative carbon dioxide and methane production measured in each flask. The calculation was based on the total organic carbon of the positive control (reference material) and test samples, and the results are shown in Table 5.
[0065] Table 5. Percentage of biodegradability of cellulose in the test samples relative to the positive control (reference material).
[0066] Considering the cumulative gas production observed in Tables 4 and 5 and their analysis, it is evident that the biodegradable fiber obtained in Example 1 underwent a biodegradation process. After 45 days of incubation, the biodegradation level of the positive control (reference material) was 90.96%, while the biodegradation rate of the biodegradable fiber obtained in Example 1 of this invention was 7.55%.
[0067] The percentage of weight loss was calculated based on the initial and final weights of the test samples after 45 days of study, and the results are shown in Table 6.
[0068] Table 6. Percentage of weight loss of the biodegradable fibers obtained in Example 1
[0069] As shown in Table 6, the weight loss percentage was 3.95%.
[0070] Figure 3 This is a graph showing the net biogas volume of the biodegradable fiber (test sample) and positive control (reference material - cellulose) obtained in Example 1; the percentage of biodegradation of the test materials was determined based on the conversion of carbon from the test materials (positive control and biodegradable fiber obtained in Example 1) to gaseous carbon (CH4 and CO2), and the results are shown in [Figure number missing]. Figure 4 and Figure 5 ,from Figures 3-5 It can be confirmed that the biodegradable fibers obtained by this invention are biodegradable.
[0071] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A method for preparing a degradable fiber, comprising the following steps: melting the preparation raw material of the skin layer and the preparation raw material of the core layer respectively, then performing skin-core composite co-extrusion to obtain a nascent fiber, and then sequentially performing cooling and oiling and plying to obtain a pre-draft yarn; performing double-twist and elastic recovery composite on the pre-draft yarn to obtain the degradable fiber; the preparation raw material of the core layer comprises the following components in percentage by mass: 98-99% of high-melting-point polyester and 1-2% of a first degradable masterbatch; the high-melting-point polyester has a melting point of 250-260°C; the first degradable masterbatch is ASMD®-PET 6000; the preparation raw material of the skin layer comprises the following components in percentage by mass: 98-99% of a low-melting-point polymer and 1-2% of a second degradable masterbatch; the low-melting-point polymer is low-melting-point polyester or polypropylene, and the low-melting-point polymer has a melting point of 150-210°C; when the low-melting-point polymer is low-melting-point polyester, the second degradable masterbatch is ASMD®-PET 6000; when the low-melting-point polymer is polypropylene, the second degradable masterbatch is ASMD®-PP 7000.
2. The production method according to claim 1, characterized by, In the preparation raw material of the degradable fiber, the mass percentage of the preparation raw material of the skin layer is 20-40%, and the mass percentage of the preparation raw material of the core layer is 80-60%.
3. The preparation method according to claim 1, characterized in that, The high-melting-point polyester further comprises drying before use, so that the water content of the dried high-melting-point polyester is less than 30 ppm.
4. The production method according to claim 1, characterized by, The low-melting-point polyester further comprises drying before use, so that the water content of the dried low-melting-point polyester is less than 50 ppm.
5. The method of claim 1, wherein, The melting temperature of the preparation raw material of the skin layer is 180-230°C.
6. The method of claim 1, wherein, The melting temperature of the preparation raw material of the core layer is 250-300°C.
7. The preparation method according to claim 1, characterized in that, The total fineness of the pre-draft yarn is 133-594 dtex, and the single-fiber fineness is 3.2-7.2 dtex.
8. The method of claim 1, wherein, Before the double-twist and elastic recovery composite, the pre-draft yarn further comprises sequentially performing first preheating and second preheating; the temperature of the first preheating and the second preheating is independently 120-150°C.
9. The method of claim 1, wherein, The conditions of the double-twist and elastic recovery composite comprise: a draft ratio of 1.6-1.8 times and an elastic recovery D / Y ratio of 1.5-3.
10. The degradable fiber prepared by the method of any one of claims 1 to 9, characterized in that, The degradable fiber is a degradable twisted skin-core fiber comprising a skin layer and a core layer; the total fineness of the degradable fiber is 167-660 dtex, and the single-fiber fineness is 2-4 dtex.