Method of forming a silk ribbon fiber crimp

Abstract

The application provides a silk fabric fiber crimping forming method, and belongs to the technical field of crimped silk fabric manufacturing, which comprises a silk bundle smoothing step, a single-side modification step, an axial dispersion step, a fiber feeding step, a pulse compression step and a setting fixing step. The silk fabric fiber crimping forming method combines differential flexure of a mechanical structure with internal stress generated by chemical modification, and solves the problems of traditional physical crimping methods, such as non-durability of crimping degree and poor fluffy feeling.

Description

Technical Field

[0001] This invention relates to the field of manufacturing crimped silk ribbons, and particularly to a method for crimping and forming silk ribbon fibers. Background Technology

[0002] Silk ribbons, due to their unique luster and feel, are widely used in high-end textiles, decoration, and apparel. To give silk ribbons better bulk, elasticity, and hand feel, the silk fibers usually need to be crimped. Currently, the most mature crimping method in the industry mainly uses mechanical extrusion, such as feeding a bundle of silk fibers into a compression chamber. The speed difference between the feeding speed and the discharge resistance causes the fibers to fold or bend, forming a bundle with a certain degree of crimp. This method has mature equipment, is easy to operate, and is widely used in the crimping processing of synthetic fibers such as polyester and nylon.

[0003] However, when the above methods are applied directly to silk ribbon fibers, especially natural protein fibers, the following problems arise that are difficult to resolve simultaneously:

[0004] First, during the unwinding process, the silk fiber bundles are prone to periodic tension fluctuations, and the fibers overlap and entangle with each other, resulting in uneven stress on individual fibers during subsequent winding. Therefore, the crimp degree varies greatly between different batches of the same batch of silk webbing, and the quality stability is insufficient.

[0005] Secondly, when chemical additives are introduced to improve crimp durability, the fibers are prone to sticking together. Once sticking occurs, the fibers are folded together as bundles, resulting in a stiff feel and insufficient fluffiness in the finished product.

[0006] Third, the curling shape formed solely by mechanical extrusion is mostly a two-dimensional plane bend. This structure is prone to springing back and straightening after being stretched or washed, resulting in a low curl retention rate.

[0007] Fourth, the fibers of silk ribbons are relatively delicate. Excessive mechanical extrusion or excessively high setting temperature can easily damage the fiber surface, resulting in decreased luster and reduced strength.

[0008] Therefore, how to induce a highly resilient and stable three-dimensional spiral crimped structure in silk fibers while protecting their original physical properties is a technical problem that urgently needs to be solved in the silk weaving and ribbon processing field. Summary of the Invention

[0009] The present invention aims to solve the above-mentioned technical problems by providing a method for crimping and forming silk ribbon fibers.

[0010] The technical solution of the present invention is a method for crimping and forming silk ribbon fibers, comprising:

[0011] Fiber bundle flattening step: The fiber bundle to be processed is fed into the tension compensation zone composed of tension regulating rollers, and flattened by a multi-stage straight roller group so that the individual fibers in the fiber bundle are arranged in parallel tension.

[0012] One-sided modification step: A penetrating crosslinking agent is sprayed onto one side of the flat fiber bundle. The spraying pressure is used to make the crosslinking agent penetrate into the fiber bundle in a directional manner. The penetration depth of the crosslinking agent in the cross-section of the fiber is controlled to form an asymmetric molecular crosslinking gradient on the cross-section of a single fiber, forming an endogenous shrinkage stress difference pre-set zone. The sprayed fiber bundle is then subjected to a preheating reaction treatment.

[0013] Axial discretization step: The modified filament bundle is fed into a decoupling roller group including at least one pair of axial reciprocating differential rollers for axial reciprocating oscillation. The axial shear force is used to break the adhesion between the fibers, so that the filament bundle is transformed into a decoupled discrete state.

[0014] Fiber feeding step: The discrete fiber bundles are fed into the compression molding cavity by a differential control component driven by an independent motor. The rate deviation formed by the internal resistance generated between the feeding roller and the narrowed part of the compression molding cavity causes the fibers to be mechanically buckled.

[0015] Pulse compression step: At the discharge end of the compression molding cavity, a periodically changing pulse resistance is applied by a pneumatic pressure plate, so that the fiber bundle in the cavity generates curled nodes distributed along the fiber axis under the combined action of the feeding pressure and the discharge resistance, and induces the individual fiber to generate a spiral twist based on the endogenous shrinkage stress difference to form a spiral geometry.

[0016] Shaping and fixing steps: The filament bundle with curled nodes is fed into a cooling zone with a temperature gradient distribution. The spiral geometry is fixed by the temperature field gradient to complete the curling and shaping.

[0017] In one embodiment, in the unilateral modification step, the permeable crosslinking agent is at least one of polycarboxylic acid, modified polyurethane, or bioenzyme crosslinking agent.

[0018] In one embodiment, in the unilateral modification step, the preheating reaction temperature is 60°C to 95°C, and the preheating reaction time is 10s to 60s.

[0019] In one embodiment, in the single-sided modification step, the spraying pressure is adjusted so that the penetration depth of the crosslinking agent in the cross-section of a single fiber is 30% to 60% of the fiber radius.

[0020] In one embodiment, in the axial discretization step, the oscillation frequency of the axial reciprocating differential roller is 10Hz~50Hz, and the axial displacement amplitude is 2mm~10mm.

[0021] In one embodiment, during the fiber feeding step, the ratio of the linear velocity of the feeding roller to the linear velocity of the traction roller provided at the discharge end of the compression molding cavity is 1.2:1 to 2.5:1.

[0022] In one embodiment, the compression molding cavity is a tapered section with a contraction angle of 10° to 30°.

[0023] In one embodiment, during the pulse compression step, the ratio of the operating frequency of the pneumatic pressure plate to the rotational speed of the independent motor is 1:10 to 1:5, and the peak value of the pulse resistance applied by the pneumatic pressure plate is 0.2 to 1.0 MPa.

[0024] In one implementation, during the shaping and fixing step, the cooling zone includes multiple temperature control zones, with a temperature difference gradient of 15°C to 30°C between adjacent temperature control zones.

[0025] In one implementation, during the filament flattening step, the tension of the single filament within the tension compensation range is controlled at 0.05 cN / dtex to 0.2 cN / dtex.

[0026] The advantages of this invention compared to existing technologies are that the method for crimping and forming silk ribbon fibers solves the problems of inconsistent crimp and poor fluffiness in traditional physical crimping methods by combining differential buckling in the mechanical structure with the endogenous stress generated by chemical modification. Tension compensation and flattening treatment ensure uniform penetration of the agent; axial discrete decoupling enhances the crimping independence of individual filaments; and the combination of pulse compression-induced helical torsion gives the silk ribbon fibers a three-dimensional crimped structure. Ultimately, this significantly improves the elasticity and feel of the silk ribbon. Attached Figure Description

[0027] Figure 1 A flowchart of a method for crimping and forming silk ribbon fibers provided for embodiments of the present invention;

[0028] Figure 2 A schematic diagram of the structure of the ribbon fiber crimping and forming equipment provided for an embodiment of the present invention. Detailed Implementation

[0029] The above and other embodiments and advantages of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0030] In one implementation, such as Figures 1 to 2 As shown.

[0031] The method for crimping and forming filament ribbon provided in this embodiment includes a filament bundle flattening step: feeding the filament bundle to be processed into a tension compensation zone composed of tension regulating rollers, and flattening it through a multi-stage straightening roller group, so that the individual fibers in the filament bundle are arranged in parallel tension; a unilateral modification step: spraying a penetrating crosslinking agent onto one side of the flattened filament bundle, using spraying pressure to make the crosslinking agent penetrate directionally into the interior of the filament bundle, controlling the penetration depth of the crosslinking agent in the cross-section of the fiber, so as to form an asymmetric molecular crosslinking gradient on the cross-section of the individual fiber, forming an endogenous shrinkage stress difference pre-set zone, and preheating the sprayed filament bundle; an axial dispersion step: feeding the modified filament bundle into a decoupling roller group including at least one pair of axial reciprocating differential rollers for axial reciprocating oscillation, using axial shear force to break The adhesion between the fibers causes the fiber bundle to transform into a decoupled discrete state. The fiber feeding step involves feeding the discrete fiber bundle into the compression molding cavity via a differential control component driven by an independent motor. The rate deviation created by the internal resistance generated between the feeding roller and the reduced diameter section of the compression molding cavity causes the fibers to mechanically buckle. The pulse compression step involves applying periodically varying pulse resistance at the discharge end of the compression molding cavity via a pneumatic pressure plate. Under the combined action of the feeding pressure and the discharge resistance, the fiber bundle within the cavity generates curled nodes distributed along the fiber axis, inducing individual fibers to spirally twist based on the inherent shrinkage stress difference to form a spiral geometry. The shaping and fixing step involves sending the fiber bundle with curled nodes into a cooling zone with a temperature gradient distribution. The temperature field gradient is used to fix the spiral geometry, completing the curling molding process.

[0032] In this embodiment, the method for crimping and forming the filament ribbon first performs a filament bundle flattening step. In this step, the filament bundle to be treated is fed into a tension compensation zone composed of tension regulating rollers. The tension compensation zone refers to a buffer path formed by multiple adjustable rollers, i.e., tension regulating rollers, to counteract the periodic tension fluctuations generated during the unwinding of the original filament cake. Subsequently, the filament bundle undergoes flattening treatment through a multi-stage straightening roller group. The multi-stage straightening roller group applies alternating compression and relaxation to the filament bundle, transforming it from a bundled state into a flat ribbon with a thickness not exceeding twice the diameter of a single fiber. This ensures that the individual fibers within the filament bundle are arranged in parallel tension, and that the vast majority of fibers are exposed on the bundle surface to receive subsequent one-sided spraying. Here, parallel tension arrangement means not only that the fibers are geometrically parallel, but also that the pre-tension borne by each filament in the axial direction tends to be consistent. This lays the foundation for the uniformity of the penetration depth of subsequent one-sided modification. In some implementation scenarios, multi-stage flat roller groups can also be equipped with a micro-vibration-assisted flattening mechanism, which further assists the cross fibers in the yarn bundle to return to their original positions through high-frequency, low-amplitude micro-vibration, reducing local stacking caused by electrostatic adsorption, thereby ensuring that the fiber density within the ribbon width is uniform after flattening.

[0033] Next, a one-sided modification step is performed. In a flat state, a penetrating crosslinking agent is sprayed onto one side of the flattened monolayer fiber bundle. Spraying pressure is used to directionally penetrate the crosslinking agent into the fiber bundle. Since the fiber bundle has been flattened to a thickness not exceeding twice the diameter of a single fiber, and the fibers are arranged in parallel, the spraying pressure allows the crosslinking agent to act directly on the side of each fiber facing the sprayed surface, thus forming an asymmetric molecular crosslinking gradient on the cross-section of each fiber. By precisely controlling the spraying pressure and fiber travel speed, the penetration depth of the crosslinking agent within the cross-section of each fiber is controlled, thereby forming an asymmetric molecular crosslinking gradient on the cross-section of each fiber. This means that within the cross-section of a single fiber, the molecular chains on the side affected by the agent form a tight network structure through crosslinking, while the side unaffected by the agent maintains its original loose arrangement, thus creating a pre-set zone of endogenous shrinkage stress difference within the fiber. The subsequent preheating reaction treatment is to use heat energy to drive the chemical bonding between the crosslinking agent and fiber molecules, solidifying this stress difference state within the fiber. Specifically, this pre-set intrinsic shrinkage stress difference is like implanting a microscopic bending memory unit within the fiber. During subsequent mechanical buckling and pulse compression, this pre-stressed region becomes the preferential starting point for deformation and torsion, guiding the fiber to produce directional helical curling under stress, rather than random, uncontrolled bending. For example, when the degree of cross-linking on one side of the fiber is significantly higher than on the other, under axial compressive load, the side with higher cross-linking resistance is stronger, forcing the fiber as a whole to bend and twist towards the side with lower cross-linking, thus spontaneously forming a helical conformation.

[0034] The axial discretization step is then performed. The modified filament bundle is fed into a decoupling roller assembly comprising at least one pair of axially reciprocating differential rollers for axial reciprocating oscillation. While rotating, the decoupling roller assembly generates reciprocating displacement along the roller axis via a mechanical linkage mechanism. This axial shear force physically breaks down the occasional adhesions between fibers caused by crosslinking agent spraying, transforming the filament bundle into a decoupled discrete state. The so-called decoupled discrete state means that each filament in the bundle is in a spatially sliding, independent state, no longer entangled with each other. This ensures that each fiber can deform independently during subsequent mechanical buckling. To further enhance the decoupling effect, the surface of the axially reciprocating differential rollers can be machined with fine oblique grooves or coated with an elastic material with a specific coefficient of friction. When the fiber bundle passes through the roller surface, this surface structure generates a transverse kneading effect, allowing even slightly crosslinked fiber pairs to completely separate under the combined action of shear and kneading forces, ensuring that the filament bundle entering the compression molding cavity achieves the ideal monofilament discrete state. This is crucial for producing finished silk ribbons with a delicate feel and excellent fluffiness, because even a small amount of fibers sticking together can form stiff knots in the final product, reducing the softness and uniformity of the fabric.

[0035] In the fiber feeding step, discrete fiber bundles are fed into the compression forming cavity via a differential control assembly driven by an independent motor. The differential control assembly provides active conveying power through the feed rollers, while the narrowing section of the compression forming cavity generates internal resistance. The rate deviation between the thrust of the feed rollers and the resistance of the narrowing section causes the fibers to mechanically buckle under pressure. Here, the rate deviation refers to the fiber's entry velocity into the cavity being greater than its velocity through the narrowing section, thus forcing it to fold within a confined space.

[0036] In the pulse compression step, periodically varying pulse resistance is applied at the discharge end of the compression molding cavity via a pneumatic pressure plate. The pneumatic pressure plate intermittently obstructs the fiber bundle at the discharge outlet through reciprocating motion, causing the fiber bundle within the cavity to generate crimp nodes distributed along the fiber axis under the combined action of the front-end feeding pressure and the rear-end pulse resistance. A crimp node is a stress concentration point where the fiber undergoes severe folding. At this node, due to mechanical compression, the fiber is induced to twist spirally based on the aforementioned intrinsic shrinkage stress difference, thus forming a microscopic spiral geometry. Experiments show that under the action of pulse resistance, the crimp nodes of the fiber exhibit a distinct spiral shape rather than simple folding, and its crimp elastic recovery rate is significantly higher than that of pure mechanical buckling. The principle behind the generation of this spiral geometry is: when the pulse resistance increases instantaneously, the fiber is forced to buckle within the cavity, initially forming an initial bending point; during the interval between the release or reduction of the pulse resistance, due to the elastic rebound of the material and the continuous action of the feeding pressure, the bent portion of the fiber begins to release strain energy. At this point, the pre-installed asymmetric cross-linking gradient within the fiber begins to function, inducing directional torsional displacement at the bend, rather than simple elastic recovery, thus transforming the in-plane bend into a three-dimensional spiral coil. This process repeats in each pulse cycle, ultimately forming a series of spiral coil nodes with memory effect along the fiber's length, giving the webbing excellent compression resilience and hand feel.

[0037] Finally, the shaping and fixing step is performed. The fiber bundle with crimped nodes is fed into a cooling zone with a temperature gradient distribution. The temperature gradient refers to the different temperature gradient zones set along the direction of travel in the cooling zone. Through step-by-step cooling, the change in temperature field locks in the spiral geometry already formed by the fiber, ultimately completing the crimping and shaping. Using a temperature gradient distribution for shaping, compared to quenching, can significantly reduce residual thermal stress inside the fiber. During the transition from the high-temperature zone to the low-temperature zone, the macromolecular chain segments in the fiber have sufficient time to adjust and rearrange, making the crosslinking points at the spiral nodes more stable.

[0038] In this embodiment, the method for crimping and forming silk ribbon fibers solves the problems of short-lasting crimp and poor fluffiness in traditional physical crimping methods by combining differential buckling in the mechanical structure with the endogenous stress generated by chemical modification. Tension compensation and flattening treatment ensure uniform penetration of the agent; axial discrete decoupling enhances the crimping independence of individual filaments; and pulse compression-induced helical torsion gives the silk ribbon fibers a three-dimensional crimped structure. Ultimately, this significantly improves the elasticity and feel of the silk ribbon.

[0039] In one embodiment, in the unilateral modification step of the method for crimping and forming the ribbon fiber, the permeable crosslinking agent is at least one of polycarboxylic acid, modified polyurethane, or bioenzyme crosslinking agent.

[0040] In this embodiment, the permeating crosslinking agent is selected from polycarboxylic acids, modified polyurethanes, or bio-enzyme crosslinking agents. These agents are chosen because they possess good molecular permeability and reactivity. Polycarboxylic acids can form stable covalent bonds with silk fiber molecules, modified polyurethanes provide good film-forming toughness, and bio-enzyme crosslinking agents can catalyze the recombination of macromolecular chain segments under mild conditions. Using at least one of these agents ensures a sufficiently strong stress gradient is formed on the monofilament cross-section. For example, butanetetracarboxylic acid or citric acid can be selected as polycarboxylic acids, which can undergo esterification or amidation reactions with hydroxyl and amino groups in the silk fiber in the presence of a catalyst to form a stable three-dimensional network structure with few reaction byproducts and minimal impact on the fiber's color. Waterborne polyurethane emulsions are preferred for modified polyurethane, as they have good wetting and spreading properties on the silk fiber surface. After penetrating to a certain depth on the fiber surface, they can form a flexible shrinkage layer on one side of the fiber cross-section through their own properties. Bio-enzyme crosslinking agents can be, for example, transglutaminase, which is particularly suitable for treating silk fibers with high heat sensitivity requirements.

[0041] In one embodiment, in the single-sided modification step of the filament webbing fiber crimping and forming method, the preheating reaction treatment temperature is 60°C~95°C and the preheating reaction treatment time is 10s~60s.

[0042] In this embodiment, the preheating reaction temperature is set to 60°C~95°C, and the processing time is 10s~60s. Within this temperature range, the crosslinking agent and fiber molecules can complete the initial reaction in a very short time, while avoiding damage to the strength of the silk fiber itself due to high temperature, thus ensuring the continuity of the production process. When the temperature is below 60°C, the crosslinking reaction rate is too slow, making it difficult to form a shrinkage stress pre-set zone with sufficient crosslinking degree within the continuous production window of 10s~60s. If the temperature exceeds 95°C and the time is prolonged, the activity of the silk fibroin molecular chain segments inside the silk fiber will intensify, which may lead to uncontrolled over-penetration of the crosslinking agent into the fiber interior, thereby weakening the gradient difference of unilateral asymmetric modification.

[0043] In one embodiment, in the single-sided modification step of the ribbon fiber crimping and forming method, the crosslinking agent is adjusted to penetrate to a depth of 30% to 60% of the fiber radius in the cross-section of a single fiber by adjusting the spraying pressure.

[0044] In this embodiment, if the penetration depth is less than 30%, the resulting shrinkage force is insufficient to drive fiber torsion; if it is greater than 60%, the cross-section tends to be symmetrical, and an effective stress difference cannot be formed. Controlling the penetration depth within this range allows the fiber to achieve the maximum helical curvature in subsequent processes. In actual operation, the spraying pressure can be adjusted using closed-loop feedback based on the fiber fineness and travel speed. For example, for finer fibers, due to their larger specific surface area and faster agent penetration, the spraying pressure can be appropriately reduced or the fiber speed increased; while for coarser fibers, the pressure needs to be appropriately increased to ensure that the agent can penetrate to the target depth. By monitoring the changes in light transmittance of the fiber bundle before and after spraying online, the penetration depth can be precisely maintained within the preferred range, thereby ensuring the consistency of the crimping effect in mass production.

[0045] In one embodiment, in the axial discretization step of the filament webbing fiber crimping and forming method, the oscillation frequency of the axial reciprocating differential roller is 10Hz~50Hz, and the axial displacement amplitude is 2mm~10mm.

[0046] In this embodiment, the oscillation frequency of the axial reciprocating differential roller is set to 10Hz~50Hz, and the axial displacement amplitude is 2mm~10mm. Through high-frequency, small-amplitude oscillation, sufficient axial friction can be generated, causing the adhesion points between fibers to undergo slight displacement and break, thereby achieving efficient decoupling without damaging the monofilaments. Specifically, if the oscillation frequency is below 10Hz, the decoupling effect may decrease due to insufficient impact energy, requiring a longer processing path to achieve the same dispersion effect; if the frequency is too high, exceeding 50Hz, the vibration noise of the mechanical system increases and is prone to causing equipment resonance. Simultaneously, excessively high instantaneous shear rates also pose a risk of damaging the surface gloss of the silk fibers. The axial displacement amplitude is controlled between 2mm and 10mm, matching the width of the flattened fiber bundle. This ensures that the entire fiber bundle receives sufficient reciprocating shearing action without causing lateral stacking or curling of the fiber bundle between the rollers due to excessive displacement amplitude.

[0047] In one embodiment, in the fiber crimping and forming method of the ribbon, the ratio of the linear velocity of the feeding roller to the linear velocity of the traction roller provided at the discharge end of the compression forming cavity is 1.2:1 to 2.5:1 during the fiber feeding step.

[0048] In this embodiment, the ratio of the linear velocity of the feed roller to the linear velocity of the traction roller at the discharge end of the compression molding cavity is set to 1.2:1 to 2.5:1. This speed ratio determines the fiber filling density within the cavity. A higher speed ratio can increase the number of crimps per unit length, thereby improving the bulkiness of the filament weave. When the speed ratio is lower than 1.2:1, the compressive internal stress established within the cavity is small, resulting in insufficient fiber mechanical buckling amplitude, leading to low crimp and a weak hand feel in the finished product. Conversely, when the speed ratio is higher than 2.5:1, although extremely high crimp density can be obtained, excessive compression may cause plastic crushing of the fibers within the cavity, damaging the fibrillary structure of the filament fibers, and consequently significantly reducing the breaking strength of the finished filament weave.

[0049] In one embodiment, the method for crimping and forming the ribbon fiber has a compression forming cavity with a tapered diameter reduction section, and the tapered diameter reduction section has a shrinkage angle of 10° to 30°.

[0050] In this embodiment, the compression molding cavity's diameter reduction section is designed as a tapered section, with a reduction angle set to 10°~30°. The tapered design guides the filament bundle smoothly into the high-pressure zone, avoiding fiber jamming or excessive damage that could result from right-angle diameter reduction.

[0051] In one embodiment, in the pulse compression step of the ribbon fiber crimping and forming method, the ratio of the operating frequency of the pneumatic pressure plate to the rotational speed of the independent motor is 1:10 to 1:5, and the peak value of the pulse resistance applied by the pneumatic pressure plate is 0.2 to 1.0 MPa.

[0052] In this embodiment, the ratio of the pneumatic pressure plate's operating frequency to the independent motor's rotational speed is set to 1:10 to 1:5, and the peak pulse resistance is 0.2 to 1.0 MPa. By controlling the coordinated ratio of the pressure plate's movement and the motor's rotational speed, the spacing distribution of the coiled nodes can be precisely controlled. The peak pulse resistance determines the tightness of the nodes, ensuring that the inducing force of the helical twist is sufficiently large. For example, when the pneumatic pressure plate's operating frequency is relatively low, the fiber bundle has more time to accumulate feed during each pulse interval, resulting in larger buckling folds when the pressure plate moves again, producing helical nodes with larger spacing but higher tightness; conversely, when the ratio is close to 1:5, the pulse frequency increases, and the distribution of coiled nodes becomes finer and more uniform.

[0053] In one embodiment, the method for crimping and forming the ribbon fiber includes a cooling zone comprising multiple temperature control zones in the shaping and fixing step, wherein the temperature difference gradient between two adjacent temperature control zones is 15°C to 30°C.

[0054] In this embodiment, the cooling zone includes multiple temperature control zones, with the temperature gradient between adjacent zones set at 15°C to 30°C. By setting this progressively decreasing temperature gradient, fiber brittleness during rapid cooling can be prevented, and the molecular chain segments gradually stabilize during the shaping process through stepwise cooling. The multiple temperature control zones typically consist of three to five temperature plateaus. For example, the first temperature control zone maintains a temperature close to that after the preheating reaction, allowing for initial stress equalization after the fiber exits the compression chamber; subsequently, the temperature decreases by 15°C to 30°C with each subsequent temperature control zone. This stepwise cooling method not only locks in the helical geometry but also effectively reduces condensation on the fiber surface, preventing the fibers from curling or losing strength due to moisture absorption.

[0055] In one embodiment, in the fiber crimping and forming method of the ribbon, the tension of the single filament within the tension compensation range is controlled at 0.05 cN / dtex to 0.2 cN / dtex during the filament flattening step.

[0056] In this embodiment, the monofilament tension within the tension compensation range is controlled between 0.05 cN / dtex and 0.2 cN / dtex. Strictly limiting the tension to this lower limit ensures that the filament bundle does not sag during travel, while also preventing irreversible plastic stretching of the fibers on the straight roller assembly due to excessive tension, thus protecting the fiber's crimping potential. When the monofilament tension is below 0.05 cN / dtex, the filament bundle tension is insufficient, failing to effectively adhere to the roller surface. This can easily lead to sagging, slippage, or deviation from the centerline when passing through multi-stage straight roller assemblies, resulting in a deterioration in the flattening effect and uneven subsequent coating. When the tension exceeds 0.2 cN / dtex, although the filament bundle's running posture is stable, the silk fibers, especially natural silk, have undergone slight pre-stretching. This pre-stretching consumes some of the fiber's crimping elasticity, weakening the fiber's buckling and torsional response in subsequent processes, ultimately reducing the crimp of the finished product.

[0057] The specific embodiments described above further illustrate the inventive purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. In particular, it should be noted that any modifications, equivalent substitutions, or improvements made by those skilled in the art within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for forming silk ribbon fibers by curling, characterized in that, include Fiber bundle flattening step: The fiber bundle to be processed is fed into the tension compensation zone composed of tension regulating rollers, and flattened by a multi-stage straight roller group so that the individual fibers in the fiber bundle are arranged in parallel tension. One-sided modification step: A penetrating crosslinking agent is sprayed onto one side of the flat fiber bundle. The spraying pressure is used to make the crosslinking agent penetrate into the fiber bundle in a directional manner. The penetration depth of the crosslinking agent in the cross-section of the fiber is controlled to form an asymmetric molecular crosslinking gradient on the cross-section of a single fiber, forming an endogenous shrinkage stress difference pre-set zone. The sprayed fiber bundle is then subjected to a preheating reaction treatment. Axial discretization step: The modified filament bundle is fed into a decoupling roller group including at least one pair of axial reciprocating differential rollers for axial reciprocating oscillation. The axial shear force is used to break the adhesion between the fibers, so that the filament bundle is transformed into a decoupled discrete state. Fiber feeding step: The discrete fiber bundles are fed into the compression molding cavity by a differential control component driven by an independent motor. The rate deviation formed by the internal resistance generated between the feeding roller and the narrowed part of the compression molding cavity causes the fibers to be mechanically buckled. Pulse compression step: At the discharge end of the compression molding cavity, a periodically changing pulse resistance is applied by a pneumatic pressure plate, so that the fiber bundle in the cavity generates curled nodes distributed along the fiber axis under the combined action of the feeding pressure and the discharge resistance, and induces the individual fiber to generate a spiral twist based on the endogenous shrinkage stress difference to form a spiral geometry. Shaping and fixing steps: The filament bundle with curled nodes is fed into a cooling zone with a temperature gradient distribution. The spiral geometry is fixed by the temperature field gradient to complete the curling and shaping.

2. The method for forming silk ribbon fibers according to claim 1, characterized in that, In the unilateral modification step, the permeable crosslinking agent is at least one of polycarboxylic acid, modified polyurethane, or bio-enzyme crosslinking agent.

3. The method for forming silk ribbon fibers according to claim 1, characterized in that, In the unilateral modification step, the preheating reaction temperature is 60°C to 95°C, and the preheating reaction time is 10s to 60s.

4. The method for forming silk ribbon fibers according to claim 1, characterized in that, In the single-sided modification step, by adjusting the spraying pressure, the penetration depth of the crosslinking agent in the cross-section of a single fiber is 30% to 60% of the fiber radius.

5. The method for forming silk ribbon fibers according to claim 1, characterized in that, In the axial discretization step, the oscillation frequency of the axial reciprocating differential roller is 10Hz~50Hz, and the axial displacement amplitude is 2mm~10mm.

6. The method for forming silk ribbon fibers according to claim 1, characterized in that, In the fiber feeding step, the ratio of the linear velocity of the feeding roller to the linear velocity of the traction roller provided at the discharge end of the compression molding cavity is 1.2:1 to 2.5:

1.

7. The method for forming a silk ribbon fiber crimping according to claim 1, characterized in that, The compression molding cavity has a tapered diameter reduction section, and the tapered diameter reduction section has a contraction angle of 10° to 30°.

8. The method for forming silk ribbon fibers according to claim 1, characterized in that, In the pulse compression step, the ratio of the operating frequency of the pneumatic pressure plate to the rotational speed of the independent motor is 1:10 to 1:5, and the peak value of the pulse resistance applied by the pneumatic pressure plate is 0.2 to 1.0 MPa.

9. The method for forming silk ribbon fibers according to claim 1, characterized in that, In the shaping and fixing step, the cooling zone includes multiple temperature control zones, and the temperature difference gradient between two adjacent temperature control zones is 15°C to 30°C.

10. The method for forming silk ribbon fibers according to claim 1, characterized in that, In the filament flattening step, the tension of the single filament within the tension compensation range is controlled at 0.05 cN / dtex to 0.2 cN / dtex.

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