Fireproofing and flame-retardant yarns of biodegradable core-sheath hollow structure and methods of making

Abstract

The application provides a biodegradable core-sheath hollow-structure fiber fireproof flame-retardant yarn and a preparation method thereof, and comprises the following steps: combining and twisting treatment of rigid fiber filaments and soluble vinylon filaments to prepare a non-damaging core yarn with a spiral structure; uniformly coating the non-damaging core yarn with soluble vinylon short fibers, and wrapping the outer layer of the soluble vinylon short fibers with polylactic acid fiber filaments to prepare a non-shrinkage yarn with balanced torque; taking the non-shrinkage yarn as a core yarn, and realizing bidirectional wrapping of polylactic acid yarn in clockwise and counterclockwise directions by using a multifunctional wrapping machine to prepare a composite yarn with a compact and stable structure; and removing the soluble vinylon short fibers and the soluble vinylon filaments in the intermediate layer of the composite yarn by using the characteristics of soluble vinylon through warm water bath to prepare a core-sheath hollow-structure yarn; and the application successfully utilizes the rigid fiber filaments to spin a biodegradable basalt fiber fireproof heat-insulating yarn composite yarn which is stable in structure, fireproof and flame-retardant, good in heat-insulating performance, high in strength and smooth.

Description

Technical Field

[0001] The present invention relates to the technical field of multi-component fiber composite spinning, in particular to a biodegradable fiber fire-retardant yarn with a core-sheath hollow structure and a preparation method thereof. Background Art

[0002] Fireproof and heat-insulating yarns play an important role in preventing fires and providing thermal protection, and have significant application significance in high-rise fire prevention and fire rescue. Currently, fireproof and heat-insulating fabrics are mainly made by spinning and weaving high-performance organic and inorganic fibers or dyeing and finishing the fabrics. Examples include polyimide fibers, flame-retardant viscose fibers, ceramic fiber-based fire-retardant fabrics, or fabrics finished with inorganic flame-retardant nanoparticles and microcapsule phase change materials. However, these products have disadvantages such as complex processes, high costs, weak effects, and non-degradability, which greatly limit the development and application of fire-retardant yarns. Basalt fiber is made by directly drawing basalt ore, which has abundant reserves in nature. It has the characteristics of low cost, natural degradation, and excellent fire-retardant effects. It is a potential material for the development of a new generation of high-performance fire-retardant yarns.

[0003] During the spinning process of basalt fiber, due to its inherent hardness and brittleness and its inability to bend, the spinning process is prone to twisting and breaking. Tangled fibers will produce burrs and are difficult to wear. In order to solve the problem that the above-mentioned rigid fibers are prone to bending and breaking during the spinning process, the basalt filaments are usually core-spun. In the prior art, patent number CN201110076746.7, entitled "A Basalt Core-Spun Yarn", proposes a method for preparing core-spun yarn with basalt filaments as the core and flame-retardant staple fibers as the shell. The specific method is to evenly coat the basalt monofilament with flame-retardant viscose fiber, pre-oxidized fiber, flame-retardant nylon fiber or / and Kevlar fiber blended fiber. The basalt core-spun yarn can be a flame-retardant woven fabric. However, it does not solve the torque imbalance problem caused by the high stiffness of the basalt fiber. At the same time, the basalt core-spun yarn has poor elasticity, which is not conducive to wearing comfort.

[0004] In addition, the invention patent with patent number CN202010764123.8 discloses a high-rigidity brittle fiber material lossless coated yarn and its spinning method and fabric, which forms a straight lossless core-shell structure composite yarn with a yarn core (basalt fiber) by forward and reverse twisting of ring spinning and friction spinning. The invention patent with patent number CN202310567380.6 also discloses a method for preparing a rigid fiber twist-free composite yarn, which spins a torque-balanced composite yarn by reverse torque of fibers of different components. Although these two methods can avoid the exposure of basalt fibers to form burrs and improve the wearability of the yarn, they cannot achieve an effective heat insulation effect, thereby further improving the fire retardant properties.

[0005] In view of this, it is necessary to design a preparation method of biodegradable core-sheath hollow structure basalt fiber fireproof and heat-insulating yarn to solve the above problems. Summary of the Invention

[0006] The main purpose of the present invention is to overcome the above shortcomings and deficiencies of the prior art and provide a method for preparing a biodegradable fiber fire-retardant yarn with a core-sheath hollow structure.

[0007] A method for preparing a biodegradable fiber fire-retardant yarn with a core-sheath hollow structure comprises the following steps:

[0008] Step 1: combining and twisting rigid fiber filaments with rigid fiber filaments to obtain a lossless core yarn with a spiral structure;

[0009] Step 2: uniformly wrapping the above-mentioned lossless core yarn with soluble vinylon staple fibers, and wrapping the outer layer of the soluble vinylon staple fibers with polylactic acid fiber filaments to obtain a torque-balanced twist-free yarn;

[0010] Step 3: Using the torque-balanced twist-free yarn as the core yarn, a multifunctional wrapping machine is used to wrap the polylactic acid yarn in both clockwise and counterclockwise directions to obtain a composite yarn with a compact and stable structure;

[0011] Step 4: Pass the composite yarn through a warm water bath, and utilize the characteristics of soluble vinylon to remove the soluble vinylon short fibers in the middle layer of the composite yarn to obtain a yarn with a core-sheath hollow structure.

[0012] In one embodiment, in step 2, the lossless core yarn in step 1 is reversely untwisted through a transverse unwinding device to obtain untwisted rigid fiber filaments, and then the soluble vinylon staple fibers are evenly coated on the rigid fiber filaments.

[0013] The present invention first performs a combined twisting treatment on the rigid fiber filaments, and then uses a transverse unwinding device to perform an untwisting treatment on them, so as to avoid the twisted rigid fiber filaments from twisting and shrinking due to their own residual torque when unwinding, and then uses the concentrated spinning method to perform a secondary twisting on the rigid fiber filaments, and ensures that the twisting multiple of the secondary twisting is equal to the twisting multiple of the combined twisting, thereby effectively avoiding the rigid fiber filaments from bending and breaking during the spinning process, which damages the structure of the rigid fiber filaments, causes the phenomenon of exposed hairiness, and affects the yarn performance.

[0014] In one embodiment, in step 2, the twist direction of the soluble vinylon staple fiber and the polylactic acid fiber filament is opposite to the twist direction of the lossless core yarn.

[0015] In one embodiment, in step 2, the twist of the soluble vinylon staple fiber and the polylactic acid fiber filament is equal to the twist of the lossless core yarn.

[0016] In one embodiment, the polylactic acid fiber filaments are bio-based polylactic acid fiber filaments, and the polylactic acid yarns are bio-based polylactic acid staple fibers. Preferably, the bio-based polylactic acid staple fibers are polylactic acid staple fiber S-twisted yarns and polylactic acid staple fiber Z-twisted yarns prepared by ring spinning technology.

[0017] In one embodiment, in step 4, the impregnated core-sheath hollow structure yarn is passed through a drying device and stretched and shaped under the action of heat and moisture to form a stable core-sheath hollow composite yarn.

[0018] In one embodiment, the effective length of the drying area of ​​the drying device is 1m-2m, and the water temperature is controlled at 60-100°C.

[0019] In one embodiment, in step 4, the effective length of the warm water bath is 1m-3m, and the water temperature is controlled at 80-100°C.

[0020] In one embodiment, in step 1, the pre-twist degree of the fiber filament is 100 T / m-600 T / m.

[0021] In one embodiment, in step 2, the polylactic acid fiber filaments pass through a self-leveling tension disk, and the tension range is controlled within 0.5N-5N.

[0022] In one embodiment, the rigid fiber filaments are preferably basalt rigid fiber filaments.

[0023] A method for preparing a biodegradable fiber fire-retardant yarn with a core-sheath hollow structure comprises the following steps:

[0024] Step 1: combining and twisting the rigid fiber filaments and the soluble vinylon filaments to obtain a lossless core yarn with a spiral structure;

[0025] Step 2: uniformly wrapping the above-mentioned lossless core yarn with soluble vinylon staple fibers, and wrapping the outer layer of the soluble vinylon staple fibers with polylactic acid fiber filaments to obtain a torque-balanced twist-free yarn;

[0026] Step 3: Using the torque-balanced twist-free yarn as the core yarn, a multifunctional wrapping machine is used to wrap the polylactic acid yarn in both clockwise and counterclockwise directions to obtain a composite yarn with a compact and stable structure;

[0027] Step 4: Pass the composite yarn through a warm water bath, and utilize the characteristics of soluble vinylon to remove the soluble vinylon staple fibers and soluble vinylon filaments in the middle layer of the composite yarn to obtain a yarn with a core-sheath hollow structure.

[0028] In one embodiment, in step 2, the lossless core yarn in step 1 is subjected to reverse untwisting, stretching and conveying treatment through a transverse unwinding device to obtain untwisted rigid fiber filaments, and then the soluble vinylon staple fibers are evenly coated on the above rigid fiber filaments.

[0029] The present invention combines and twists rigid fiber filaments with soluble vinylon flexible filaments to improve the flexibility of the core yarn, and then uses a transverse unwinding device to stretch and transport it, avoiding the twisting of the twisted core yarn due to its own residual torque during unwinding. Then, the core yarn is twisted in the same multiple in the opposite direction using ring spinning technology, and the surface of the core yarn is coated with soluble vinylon staple fibers, while the outermost layer is wrapped with polylactic acid filaments to form a structurally stable core-spun yarn, which effectively avoids the bending and breaking of basalt filaments during the spinning process, resulting in burrs. Through the above method, rigid fiber filaments made of basalt are successfully spun to produce biodegradable basalt fiber fireproof and heat-insulating yarn composite yarns with stable structure, fire retardancy, good heat insulation performance, high strength and smoothness. It can be understood that this method can be extended to the organic composite process of other rigid fibers and flexible fibers to develop multifunctional composite yarns.

[0030] A biodegradable fiber fire-retardant yarn with a core-sheath hollow structure comprises a core yarn, an air layer and an outer sheath arranged in sequence from the inside out. The core yarn is formed by twisting rigid fiber filaments and polylactic acid fiber filaments, and the outer sheath is formed by symmetrically wrapping the polylactic acid yarn in clockwise and counterclockwise directions.

[0031] The core yarn of the present invention is twisted together from rigid fiber filaments and polylactic acid fiber filaments, resulting in high strength and flexibility. After dissolving the soluble vinylon staple fibers and soluble vinylon filaments, an air layer forms between the outer sheath and the core yarn. Friction and entanglement between the fibers create a stable structure. The bio-based polylactic acid staple fiber composite core-sheath structure ensures the fireproof, flame-retardant, and high-strength properties of the basalt rigid fibers while imparting efficient thermal insulation and flame retardancy to the composite yarn. It also isolates the basalt filaments from external friction during use, improving wearability and service life.

[0032] The present invention overcomes the key problem in the prior art that basalt fiber cannot be directly taken due to its high rigidity and brittleness. A core-sheath basalt fiber fireproof and heat-insulating yarn hollow structure is obtained through a specific preparation method. The composite structure yarn has excellent fireproof, flame retardant and heat-insulating properties, and the polylactic acid fiber on the surface ensures the skin-friendliness of the yarn, making the yarn suitable for the production of protective and rescue products such as household fireproof curtains, life ropes, firefighting suits, high-temperature protective workwear, and fire tents.

[0033] The outer sheath of this invention utilizes polylactic acid staple fiber yarn. The cross-wrapping design not only ensures a stable yarn structure, but also creates a smooth outer sheath layer that enhances toughness and feel, extending the yarn's service life. Furthermore, polylactic acid fiber is flame-retardant and smokeless, enhancing the yarn's overall fire resistance. Furthermore, polylactic acid fiber is biodegradable, and its production raw materials are plentiful and inexpensive. When combined with basalt fiber, it creates a green, low-carbon yarn. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a schematic block diagram of Example 1 of the method for preparing the biodegradable fiber fire-retardant yarn with a core-sheath hollow structure of the present invention;

[0035] Figure 2 This is a schematic diagram of the structure used in step 1 of the method for preparing the biodegradable fiber fire-retardant yarn with a core-sheath hollow structure of the present invention;

[0036] Figure 3 This is a schematic diagram of the structure used in step 1 of the method for preparing the biodegradable fiber fire-retardant yarn with a core-sheath hollow structure of the present invention;

[0037] Figure 4 This is a schematic diagram of the structure used in step 4 of the method for preparing the biodegradable fiber fire-retardant yarn with a core-sheath hollow structure of the present invention;

[0038] Figure 5 This is a schematic block diagram of Example 2 of the method for preparing the biodegradable fiber fire-retardant yarn with a core-sheath hollow structure of the present invention;

[0039] Figure 6 This is a schematic structural diagram of the biodegradable core-sheath hollow structure fiber fire-retardant yarn of the present invention. DETAILED DESCRIPTION

[0040] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0041] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0042] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature identified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0043] In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connect," "fixed," etc. should be understood broadly. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0044] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0045] The present invention provides a method for preparing a biodegradable fiber fire-retardant yarn with a core-sheath hollow structure, comprising the following steps:

[0046] Step 1: combining and twisting the rigid fiber filaments and the soluble vinylon filaments to obtain a lossless core yarn with a spiral structure;

[0047] Step 2: uniformly wrapping the above-mentioned lossless core yarn with soluble vinylon staple fibers, and wrapping the outer layer of the soluble vinylon staple fibers with polylactic acid fiber filaments to obtain a torque-balanced twist-free yarn;

[0048] Step 3: Using the torque-balanced twist-free yarn as the core yarn, a multifunctional wrapping machine is used to wrap the polylactic acid yarn in both clockwise and counterclockwise directions to obtain a composite yarn with a compact and stable structure;

[0049] Step 4: Pass the composite yarn through a warm water bath, and utilize the characteristics of soluble vinylon to remove the soluble vinylon staple fibers and soluble vinylon filaments in the middle layer of the composite yarn to obtain a yarn with a core-sheath hollow structure.

[0050] The present invention combines and twists rigid fiber filaments with soluble vinylon flexible filaments to improve the flexibility of the core yarn, and then uses a lateral unwinding device to stretch and transport it to avoid the twisting of the twisted core yarn due to its own residual torque during unwinding; then uses ring spinning technology to twist the core yarn in the same multiple in the opposite direction, coats the surface of the core yarn with soluble vinylon staple fibers, and wraps polylactic acid filaments on the outermost layer to form a structurally stable core-spun yarn, which effectively avoids the bending and breaking of basalt filaments during the spinning process and the generation of burrs; through the above method, rigid fiber filaments made of basalt material are successfully spun to produce biodegradable basalt fiber fireproof and heat-insulating yarn composite yarn with stable structure, fire retardancy, good heat insulation performance, high strength and smoothness.

[0051] Example 1

[0052] See also Figures 1 to 4 The present invention provides a method for preparing a biodegradable fiber fire-retardant yarn with a core-sheath hollow structure, comprising the following steps:

[0053] Step S101: first unwind two rigid fiber filaments from the first filament reel 1 and the second filament reel 5 respectively, pass through the double-groove guide wheel 2 and the single-groove guide wheel 3 in turn, and move to the side of the first winding spindle 4 under the restriction of the first guide hook 6. The rigid fiber filaments are combined and twisted by the rotation of the first winding spindle 4 to obtain rigid fiber filaments with a twist of 30 twists / cm. The rigid fiber filaments that have undergone the above twisting treatment are wound onto the first winding spindle 4 for standby use; the rigid fiber filaments are preferably fiber filaments made of basalt, but can also be other rigid fibers.

[0054] Step S102: The rigid fiber filament with a twist of 30 twists / cm on the first winding spindle 4 in step S101 is placed on the unwinding shaft 14 of the transverse unwinding device 7 and fixed by the fixing piston 18 to ensure that the reel of the rigid fiber filament is fixed on the unwinding shaft 14. The transverse unwinding device 7 is used to perform reverse untwisting on the rigid fiber filament with a certain twist to obtain untwisted rigid fiber filament; the rigid fiber filament unwound from the reel is introduced into the unwinding shaft 14 through the godet 8;

[0055] At the same time, the soluble vinylon staple fiber is unwound from the staple fiber roving tube 11, and is gripped and stretched by the rear roller 12, the middle roller 13, and the front roller 9 in sequence and fed in parallel with the rigid fiber filaments. The soluble vinylon staple fiber is evenly coated on the surface of the rigid fiber filaments and moves toward the side of the second winding spindle 10 under the restriction of the second wire guide hook 17. The rotation of the second winding spindle 10 drives the rigid fiber filaments to undergo secondary twisting to produce rigid fiber untwisted yarn, which is wound onto the second winding spindle 10.

[0056] Step S103: Using the torque-balanced untwisted yarn as the core yarn, a multifunctional wrapping machine is used to realize clockwise and counterclockwise bidirectional wrapping of the polylactic acid yarn to obtain a composite yarn with a compact and stable structure; wherein the polylactic acid yarn is a polylactic acid staple fiber S-twisted yarn and a polylactic acid staple fiber Z-twisted yarn prepared by ring spinning technology.

[0057] Step S104, please refer to Figure 4 The composite yarn is passed through a warm water bath, and the properties of soluble vinylon are utilized to remove the middle layer of the composite yarn, thereby removing the soluble vinylon staple fibers, thereby producing a core-sheath hollow yarn. The soluble vinylon staple fibers are made of bio-based polylactic acid staple fiber bundles.

[0058] The dimensions of the first winding spindle 4 and the second winding spindle 10 are 25 mm; the diameter of the godet 8 is 8 cm, and the length of the internal rolling shaft is 7 cm; the unwinding speed of the transverse unwinding device 7 is 9.9 cm / min; the twist of the soluble vinylon staple fiber is 90 twists / cm, and the yarn count is 30. The twist multiple of the secondary twisting in step S102 is the same as the twist multiple of the twisting treatment in step S101, both being 30 twists / cm.

[0059] Among them, the guide wheel 8 can guide the rigid fiber filaments to avoid the bending of the fiber filaments after the rigid fiber filaments with a certain twist are unwound from the transverse unwinding device 7, so as to ensure that the shape of the rigid fiber filaments changes as much as possible during the spinning process. The guide wheel 8 can rotate around the rolling axis inside it.

[0060] More specifically, in step S102, the unwinding speed of the lateral unwinding device 7 is 30 m / min, and the unwinding speed is equal to the linear speed of the front roller 9, ensuring that the rigid fiber filaments always remain in a straight state, avoiding the retraction of the rigid fiber filaments, so that the twist and structure of the rigid fiber filaments are not changed or destroyed after unwinding, ensuring the stability of the rigid fiber filament structure.

[0061] More specifically, see Figure 3 In step S102, the transverse unwinding device 7 includes a support arm perpendicular to the ground and an unwinding shaft 14 mounted on the upper portion of the support arm. One end of the unwinding shaft 14 is fixed to the support arm, and the other end is provided with a fixing piston 18 that secures the first winding spindle 4 to the unwinding shaft 14. An unwinding speed adjustment switch 15 and a device switch 16 are provided on the wall of the support arm. More specifically, a magnetic base with a T-shaped cross-section is provided at the bottom of the support arm. This configuration imparts magnetic properties to the support arm and ensures the stability of the transverse unwinding device 7.

[0062] Example 2

[0063] See also Figure 5 The present invention provides a method for preparing a biodegradable fiber fire-retardant yarn with a core-sheath hollow structure, comprising the following steps:

[0064] Step S101: first unwind a rigid fiber filament and a soluble vinylon filament from the first filament reel 1 and the second filament reel 5 respectively, pass through the double-groove guide wheel 2 and the single-groove guide wheel 3 in turn, and move toward the side of the first winding spindle 4 under the restriction of the first guide hook 6. The rotation of the first winding spindle 4 drives the rigid fiber filament and the soluble vinylon filament to be combined and twisted to obtain a lossless core yarn with a spiral structure with a twist of 30 twists / cm. The rigid fiber filament that has undergone the above-mentioned twisting treatment is wound onto the first winding spindle 4 for standby use.

[0065] Step S102, put the lossless core yarn with a twist of 30 twists / cm on the first winding spindle 4 in step S101 on the unwinding shaft 14 of the transverse unwinding device 7, and fix it by the fixed piston 18 to ensure that the reel of the lossless core yarn is fixed on the unwinding shaft 14, and use the transverse unwinding device 7 to reverse untwist the lossless core yarn with a certain twist to obtain the untwisted rigid fiber filament; the rigid fiber filament unwound from the reel is introduced through the guide wheel 8; among them, the soluble vinylon filament is combined and twisted with the rigid fiber filament to improve the flexibility of the core yarn, and then the transverse unwinding device 7 is used to stretch and transport it to avoid the twisting of the twisted core yarn due to its own residual torque during unwinding.

[0066] At the same time, the soluble vinylon staple fiber is unwound from the staple fiber roving tube 11, and is gripped and stretched by the rear roller 12, the middle roller 13, and the front roller 9 in sequence and fed in parallel with the rigid fiber filaments. The soluble vinylon staple fiber is evenly coated on the surface of the rigid fiber filaments and moves toward the side of the second winding spindle 10 under the restriction of the second wire guide hook 17. The rotation of the second winding spindle 10 drives the rigid fiber filaments to undergo secondary twisting to produce rigid fiber untwisted yarn, which is wound onto the second winding spindle 10.

[0067] Step S103: Using the torque-balanced untwisted yarn as the core yarn, a multifunctional wrapping machine is used to wrap the polylactic acid yarn in both clockwise and counterclockwise directions to obtain a composite yarn with a compact and stable structure.

[0068] Step S104: passing the composite yarn through a warm water bath, and utilizing the characteristics of soluble vinylon to remove the middle layer of the composite yarn, that is, removing the soluble vinylon staple fibers and the soluble vinylon flexible filaments to obtain a yarn with a core-sheath hollow structure.

[0069] Example 3

[0070] See also Figure 6 The present invention provides a biodegradable core-sheath hollow structure fiber fire-retardant yarn, comprising a core yarn 100, an air layer 200 and an outer sheath 300 arranged in sequence from the inside to the outside. The core yarn 100 is formed by twisting rigid fiber filaments and polylactic acid fiber filaments, and the outer sheath 300 is formed by symmetrically wrapping polylactic acid yarn in clockwise and counterclockwise directions.

[0071] The core yarn 100 of the present invention is twisted together from rigid fiber filaments and polylactic acid fiber filaments, resulting in high strength and flexibility. After dissolving the soluble vinylon staple fibers and soluble vinylon filaments, an air layer 200 is formed between the outer sheath 300 and the core yarn 100. Friction and entanglement between the outer sheath 300 and the core yarn 100 simultaneously form a stable structure. The bio-based polylactic acid staple fiber composite core-sheath structure ensures the fireproof, flame-retardant, and high-strength properties of the basalt rigid fibers while imparting efficient thermal insulation and flame retardancy to the composite yarn. Furthermore, it isolates the basalt filaments from external friction during use, improving wearability and service life.

[0072] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0073] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A method for preparing a biodegradable fiber fire-retardant yarn with a core-sheath hollow structure, characterized in that: The steps include: Step 1: combining and twisting rigid fiber filaments with rigid fiber filaments to obtain a lossless core yarn with a spiral structure; Step 2: uniformly wrapping the above-mentioned lossless core yarn with soluble vinylon staple fibers, and wrapping the outer layer of the soluble vinylon staple fibers with polylactic acid fiber filaments to obtain a torque-balanced twist-free yarn; Step 3: Using the torque-balanced twist-free yarn as the core yarn, a multifunctional wrapping machine is used to wrap the polylactic acid yarn in both clockwise and counterclockwise directions to obtain a composite yarn with a compact and stable structure; Step 4: Pass the composite yarn through a warm water bath, and utilize the characteristics of soluble vinylon to remove the soluble vinylon short fibers in the middle layer of the composite yarn to obtain a yarn with a core-sheath hollow structure.

2. The method for preparing the biodegradable fire-retardant yarn with a core-sheath hollow structure according to claim 1, characterized in that: In the step 2, the lossless core yarn in step 1 is reversely untwisted by a transverse unwinding device to obtain untwisted rigid fiber filaments, and then the soluble vinylon staple fibers are evenly coated on the rigid fiber filaments.

3. The method for preparing the biodegradable fire-retardant yarn with a core-sheath hollow structure according to claim 1, characterized in that: In the step 2, the twist direction of the soluble vinylon staple fiber and the polylactic acid fiber filament is opposite to the twist direction of the lossless core yarn.

4. The method for preparing the biodegradable fire-retardant yarn with a core-sheath hollow structure according to claim 1, characterized in that: In the step 2, the twist of the soluble vinylon staple fiber and the polylactic acid fiber filament is equal to the twist of the lossless core yarn.

5. The method for preparing the biodegradable fire-retardant yarn with a core-sheath hollow structure according to claim 1, characterized in that: In the step 4, the impregnated core-sheath hollow structure yarn passes through a drying device and is stretched and shaped under the action of heat and moisture to form a stable core-sheath hollow composite yarn.

6. The method for preparing the biodegradable fire-retardant yarn with a core-sheath hollow structure according to claim 5, characterized in that: The effective length of the drying area of ​​the drying device is 1m-2m, and the water temperature is controlled at 60-100°C.

7. The method for preparing the biodegradable fire-retardant yarn with a core-sheath hollow structure according to claim 1, characterized in that: In step 4, the effective length of the warm water bath is 1m-3m, and the water temperature is controlled at 80-100°C.

8. A method for preparing a biodegradable fiber fire-retardant yarn with a core-sheath hollow structure, characterized in that: The steps include: Step 1: combining and twisting the rigid fiber filaments and the soluble vinylon filaments to obtain a lossless core yarn with a spiral structure; Step 2: uniformly wrapping the above-mentioned lossless core yarn with soluble vinylon staple fibers, and wrapping the outer layer of the soluble vinylon staple fibers with polylactic acid fiber filaments to obtain a torque-balanced twist-free yarn; Step 3: Using the torque-balanced twist-free yarn as the core yarn, a multifunctional wrapping machine is used to wrap the polylactic acid yarn in both clockwise and counterclockwise directions to obtain a composite yarn with a compact and stable structure; Step 4: Pass the composite yarn through a warm water bath, and utilize the characteristics of soluble vinylon to remove the soluble vinylon staple fibers and soluble vinylon filaments in the middle layer of the composite yarn to obtain a yarn with a core-sheath hollow structure.

9. The method for preparing the biodegradable fire-retardant yarn with a core-sheath hollow structure according to claim 8, characterized in that: In the step 2, the lossless core yarn in step 1 is subjected to reverse untwisting, stretching and conveying treatment through a transverse unwinding device to obtain untwisted rigid fiber filaments, and then the soluble vinylon staple fibers are evenly coated on the rigid fiber filaments.

10. A biodegradable fiber fire-retardant yarn with a core-sheath hollow structure, characterized in that: The biodegradable core-sheath hollow structure fiber fire-retardant yarn is made by the preparation method of any one of claims 1 to 9, comprising a core yarn, an air layer and an outer sheath arranged in sequence from the inside to the outside, the core yarn being twisted together by rigid fiber filaments and polylactic acid fiber filaments, and the outer sheath being formed by symmetrically wrapping the polylactic acid yarn in clockwise and counterclockwise directions.

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