Normal temperature and pressure dyeable PVC fiber and its preparation method

Abstract

The application provides a normal-temperature and normal-pressure dyeable PVC fiber and a preparation method thereof, and comprises a PVC fiber, wherein the PVC fiber contains a modified silkworm protein powder / MOF composite material, the modified silkworm protein powder / MOF composite material is a modified silkworm silk protein powder wrapped by a MOF material, the compatibility and heat resistance of the modified silkworm protein are strengthened through enzymatic modification and MOF encapsulation, and the on-line addition melt spinning process is combined, so that the problems of difficult dyeing, poor modification effect, insufficient environmental protection and economy of the existing PVC fiber are solved.

Description

A room-temperature and room-pressure dyeable PVC fiber and its preparation method Technical Field

[0001] This invention relates to PVC fibers, and more particularly to a room-temperature and room-pressure dyeable PVC fiber and its preparation method. Background Technology

[0002] Polyvinyl chloride (PVC) fiber, with its excellent chemical stability, corrosion resistance, and cost-effectiveness, has broad application prospects in various fields such as textile fabrics, home decoration, and industrial filter materials. However, its insufficient dyeing performance has become a core bottleneck restricting the expansion of PVC fiber into high-end application scenarios. The specific defects are mainly reflected in three aspects: First, the types of dyes that can be dyed are limited. PVC fiber can only be compatible with a few disperse dyes, making it difficult to meet diverse color requirements. Second, the molecular structure of PVC fiber lacks dye-affinity functional groups, resulting in weak binding ability with high-brightness dyes and poor dyeing effects. Third, its heat resistance is poor. PVC fiber softens and shrinks at 60-70℃, making it unsuitable for the conventional high-temperature dyeing processes in the textile industry.

[0003] To address these issues, existing technologies often employ carrier-assisted dyeing methods. However, this process is not only cumbersome and increases production costs, but also causes environmental pollution due to carrier residue, which is inconsistent with the concept of green production. Furthermore, the heat stabilizers and lubricants added during the melt spinning of PVC fibers further weaken the fiber's dyeability, ultimately leading to quality problems such as low color fastness and uneven color distribution in the finished product.

[0004] Our research team discovered that recycled materials such as silk, silkworm cocoons, and waste silk products are rich in natural proteins. These proteins possess numerous active groups such as amino and carboxyl groups on their molecular chains, exhibiting excellent dyeing affinity. Effective compounding with PVC could significantly improve the dyeing performance of fibers while preserving the original superior properties of PVC. However, two major challenges exist in practical application: firstly, silkworm protein has extremely poor compatibility with the PVC matrix, making uniform dispersion and stable bonding difficult; secondly, silkworm protein is prone to degradation under the high-temperature environment of PVC melt spinning, rendering its modifying effect ineffective. These two problems severely limit the large-scale application of silkworm protein in PVC melt spinning modification. Summary of the Invention

[0005] The purpose of this invention is to provide a room-temperature and room-pressure dyeable PVC fiber and its preparation method. By enzymatic modification and MOF encapsulation to enhance the compatibility and heat resistance of silk protein with PVC, and by combining online addition melt spinning process, the invention solves the problems of difficult dyeing, poor modification effect, and insufficient environmental protection and economy of existing PVC fibers.

[0006] To achieve the above objectives, this technical solution provides a method for preparing room-temperature and room-pressure dyeable PVC fibers, comprising the following steps:

[0007] 1) Take dried silk raw material, add neutral protease, and place it in a buffer solution at 40-50℃ and pH 6.5-8.0 for 1-4 hours to obtain silk protein solution;

[0008] 2) Add 2,3-epoxypropyltrimethylammonium chloride to the silkworm protein solution and react at 55-65℃ for 2-5 hours to obtain a modified silkworm protein solution. Spray dry and grind the modified silkworm protein solution to obtain modified silkworm protein with a particle size of 0.5~2μm.

[0009] 3) Modified silkworm protein was dispersed in MOF precursor liquid and prepared into silkworm protein powder / MOF composite material by solvothermal method;

[0010] 4) The silkworm protein powder / MOF composite material was dispersed in tributyl citrate, and an antioxidant, PCL graft copolymer and coupling agent were added to prepare the silkworm protein powder / MOF composite emulsion.

[0011] 5) The silkworm protein powder / MOF composite emulsion is added to the PVC melt during the PVC melt spinning process, and after thorough mixing, it is spun to obtain room temperature and pressure dyeable PVC fiber.

[0012] It should be noted that the room-temperature and ambient-pressure dyeable PVC fiber prepared by this method has significantly improved dyeability compared to existing PVC fibers. It can complete the dyeing of PVC under normal temperature and pressure, that is, without the need for high temperature or carrier assistance, and can be dyed with a variety of acidic, reactive and cationic dyes under normal temperature and pressure (fixation rate ≥90%, color fastness to grade 4 or above). At the same time, it simultaneously improves the fiber's mechanical properties (breaking strength 2.8-3.2 cN / dtex) and heat resistance (heat shrinkage rate 10%-20%). Moreover, the raw material is recycled waste silk, realizing resource recycling. The process does not require modification of existing equipment and is easy to industrialize. It solves the problems of difficult dyeing of existing PVC fibers, limited dye types, poor modification effect, and insufficient environmental protection and economy.

[0013] Specifically, in step 1), this method uses a neutral protease to enzymatically hydrolyze the silk raw material, transforming the dried silk raw material into a silk protein solution with dye affinity potential through enzymatic hydrolysis. The neutral protease in this method can precisely break some peptide bonds in the silk protein molecular chain under conditions of 40-50℃ and pH 6.5-8.0. On the one hand, this releases more active sites such as amino and carboxyl groups, providing a "dye affinity group reserve" for the final room-temperature dyeing of the fiber; on the other hand, the enzymatic hydrolysis process also lays the foundation for the subsequent cationic modification of the silk protein and its composite with MOF materials, ensuring uniform dispersion and avoiding the problem of unhydrolyzed large molecular proteins being difficult to combine with other components.

[0014] In some embodiments, the silk raw material is selected from one or a combination of silk, silkworm cocoons and waste silk products.

[0015] In some embodiments, the neutral protease is selected from one or a combination of serratiptase, sertratiptase, aspergillus oryzae protease, and rhizopus protease, the enzymatic activity of which is adapted to an environment of pH 6.5-8.0 to maintain high catalytic activity in the buffer composition.

[0016] In some embodiments, the buffer is a phosphate buffer, a Tris-HCl buffer, or a HEPES buffer.

[0017] In some embodiments, the mass fraction of neutral protease is 0.5%-1.2%.

[0018] In some embodiments, the degree of enzymatic hydrolysis of silk in the silk protein solution is 5% to 15%.

[0019] It should be noted that this method controls the degree of enzymatic hydrolysis of silk by adjusting enzyme concentration, reaction temperature, pH value, and reaction time. The reason for controlling the degree of hydrolysis is primarily for subsequent modification. The reaction mainly involves interaction with functional groups (carboxyl, hydroxyl, and amino groups) in silk fibroin. Excessive hydrolysis results in the protein being cleaved into very small peptides or even amino acids. These small peptides cannot provide effective skeletal support and interaction when subsequently complexed with MOF. Conversely, insufficient hydrolysis prevents the effective opening and dissolution of the large silk fibroin molecular chains, resulting in a large number of raw material fragments or aggregates in the solution. This leads to high solution viscosity, making it difficult to process and causing uneven reaction with the modifier. The final composite modified powder may have excessively large or uneven particle diameters, affecting its dispersion in PVC resin.

[0020] In some embodiments, the silk raw material needs to be dried, and the dried silk raw material is mixed with a neutral protease for enzymatic hydrolysis. Further, the silk protein is dried at 40-60°C for 10-48 hours.

[0021] In step 2), this method adds 2,3-epoxypropyltrimethylammonium chloride to the silkworm protein solution to allow the epoxy group to undergo a ring-opening reaction with the amino group of the silkworm protein, thereby directionally introducing quaternary ammonium salt cationic groups. Subsequently, the quaternary ammonium salt cationic groups can be combined with or adapted to dyes, thus completely changing the limitation that the original PVC fiber can only use disperse dyes.

[0022] In some embodiments, 2%-5% of 2,3-epoxypropyltrimethylammonium chloride is added to the silkworm protein solution, and the mixture is reacted at 55-65°C for 2-5 hours to obtain a modified silkworm protein solution. This avoids both insufficient dosage leading to inadequate grafting of dyeophilic groups and weak subsequent dyeing ability, and excessive dosage causing GTA residue, thus preventing the introduction of impurities during subsequent compounding with MOF materials or spinning. The reaction temperature of 55-65°C is within the suitable reactivity range of GTA and is far below the high-temperature degradation threshold of silkworm protein, which can efficiently promote the grafting reaction while protecting the molecular structure of silkworm protein from damage.

[0023] In some embodiments, the modified silkworm protein solution is spray-dried to obtain powder, wherein the spray-drying conditions are an inlet air temperature of 150-180°C and an outlet air temperature of 80-90°C.

[0024] In some embodiments, the powder obtained by spray drying is ground using an ultrafine pulverizer to obtain modified silkworm protein with a particle size of 0.5~2μm. This has the advantage of enhancing the binding ability of the modified silkworm protein to dyes and improving its dispersibility in PVC melt.

[0025] In step 3), this scheme uses a metal-organic framework (MOF) to encapsulate the silkworm protein powder, thereby improving the heat resistance of the modified silkworm protein powder. PVC melt spinning requires a high-temperature environment of 170-190℃, but unprotected silkworm protein is prone to structural damage and loss of active groups at this temperature, leading to modification failure. Therefore, this scheme uses a MOF material with a stable porous crystalline framework to encapsulate the modified silkworm protein in its pores or cavities, forming a physical barrier to isolate the high temperature from damaging the silkworm protein molecular chains. This ensures that the quaternary ammonium salt groups, amino groups, and other dye-friendly active sites on the surface of the silkworm protein are retained after spinning, providing an active basis for subsequent room-temperature dyeing.

[0026] In some embodiments, MOFs include, but are not limited to, ZIF-8, UiO-66, UiO-67, MOF-5, ZIF-8@Mxene, and MOF-5@graphene.

[0027] In some embodiments, the conditions for the solvothermal method are a reaction temperature of 100-150°C, a reaction time of 10-48 h, and a reaction solvent selected from one or more of DMF, methanol, anhydrous ethanol, and deionized water.

[0028] In step 4), this scheme prepares a stable silkworm protein powder / MOF composite emulsion by selecting a dispersion carrier and auxiliaries. This avoids the formation of white spots or uneven dyeing inside the fiber due to agglomeration of the powder during subsequent spinning, and ensures that each fiber can have a uniform distribution of dye-affinity active sites.

[0029] This solution selects tributyl citrate as the dispersion carrier because of its compatibility, which allows the composite material to be uniformly dispersed to form a stable emulsion. Simultaneously, tributyl citrate has a plasticizing effect, which can improve the melt flowability of PVC, facilitating the uniform dispersion of the composite material in PVC and its spinning process.

[0030] In some embodiments, the antioxidant is selected as antioxidant 1010, and the coupling agent is selected as KH560. The three types of additives used in this scheme each have a core function: antioxidant 1010 prevents the composite material from oxidative degradation during subsequent high-temperature spinning, protecting the dye-loving groups; the PCL graft copolymer forms hydrogen bonds with the hydroxyl groups of silkworm protein through its ester groups, and its chain segments are partially compatible with PVC chain segments, bringing the interface distance between the composite material and the PVC matrix closer; the coupling agent KH560 further chemically connects the two, improving compatibility at the molecular level and ultimately preventing the fiber from experiencing a decline in mechanical properties due to poor interfacial bonding.

[0031] In some embodiments, the mass fraction of the silkworm protein powder / MOF composite emulsion is 5-25%, wherein the amount of antioxidant added is 0.5-2% of the mass of the silkworm protein powder / MOF composite material, the number average molecular weight of the PCL graft copolymer is 5000-8000, the amount added is 3-6% of the mass of the silkworm protein powder / MOF composite material, and the amount of coupling agent added is 0.5-5% of the mass of the silkworm protein powder / MOF composite material.

[0032] In step 5), the silkworm protein powder / MOF composite emulsion is uniformly mixed into the PVC melt by adding an online melt spinning process. After thorough mixing, spinning is completed under specific conditions. This achieves deep integration between the composite emulsion and the PVC matrix, ensuring that the dye-loving active sites of the modified silkworm protein are uniformly distributed in the fiber, and finally produces PVC fiber with room temperature and pressure dyeing capability. Since there is no need to modify the existing spinning equipment, the industrial feasibility and production stability of the process are taken into account.

[0033] In some embodiments, this solution uses a multi-frequency high-frequency shear melt extrusion system for polyvinyl chloride melt spinning. The multi-frequency high-frequency shear melt extrusion system is equipped with a multi-screw system and an online addition system. Specifically, PVC resin enters the barrel through the feed inlet at the front end of the screw extruder via a feeder, and silkworm protein powder / MOF composite emulsion is injected into the barrel through an online addition feed inlet located after the feed inlet. It is fully mixed with PVC resin in the barrel to achieve the preparation of highly uniform modified polyvinyl chloride melt.

[0034] In some embodiments, the amount of silkworm protein powder / MOF composite emulsion added is 5-15% of the mass of polyvinyl chloride.

[0035] In some embodiments, the spinning conditions are: screw temperature in each zone is 150-180°C, spinning temperature is 170-190°C, and spinning speed is 800-2300 m / min.

[0036] In some embodiments, the spun yarn is drawn and set, wherein the drawing ratio is 2-6 times and the setting temperature is 60-70°C.

[0037] As mentioned above, the chemical reaction process of the preparation method of the room temperature and pressure dyeable PVC fiber is shown in Figure 2, and the structure of the room temperature and pressure dyeable PVC fiber after the above-mentioned technical means is shown in Figure 1. It can be seen that it contains modified silk protein powder / MOF composite material. The modified silk protein powder / MOF composite material is modified silk protein powder wrapped by MOF material, which can be dyed under room temperature and pressure conditions.

[0038] Furthermore, the fibers can be dyed using any or a combination of acid dyes, reactive dyes and / or cationic dyes at room temperature and pressure. The dyeing temperature is 30-45℃, the pH value is 3.5-5, the dyeing time is 40-50 minutes, and the dye dosage is 2%-5%. The color fixation rate of the dyeable PVC fibers after dyeing at room temperature and pressure is ≥90%, and the color fastness (soap washing, rubbing) is ≥4.

[0039] Compared with existing technologies, this technical solution has the following characteristics and beneficial effects:

[0040] (1) It enables multi-dye compatible dyeing at normal temperature and pressure, improves the color fixation rate by 10%-15%, and achieves color fastness of grade 4 or above, solving the core problem of "difficult dyeing and limited dye types" of existing PVC fibers. At the same time, it extends to cationic dyeing to meet diverse color requirements.

[0041] (2) By modifying the silkworm protein powder, the heat resistance, dispersibility and compatibility with PVC substrate are improved. The improved compatibility increases the fiber breaking strength from 2.0-2.5 cN / dtex in the prior art to 2.8-3.2 cN / dtex, and the heat shrinkage rate decreases from 30%-40% to 10%-20%.

[0042] (3) The online addition process does not require major modifications to existing melt spinning equipment and is easy to implement industrially.

[0043] (4) By using silkworm silk, silkworm cocoons and waste silk products as raw materials, the recycling of resources is realized, which is in line with the concept of green environmental protection. Attached Figure Description

[0044] Figure 1 is a schematic diagram of the structure of the room temperature and pressure dyeable PVC fiber prepared by this method.

[0045] Figure 2 is a schematic diagram of the chemical reaction process of dyeable PVC fibers at room temperature and pressure in this scheme.

[0046] Figure 3 shows scanning electron microscope images of the dyeable PVC fibers at room temperature and pressure before and after dyeing according to this scheme. (a) Before dyeing, (b) Silkworm protein powder / MOF composite material on the fiber surface before dyeing, (c) After dyeing.

[0047] Figure 4. Schematic diagram of the multiple high-frequency shearing and online addition system.

[0048] In the diagram: 1-Feeder, 2-PVC resin inlet, 3-Online addition system inlet, 4-Negative pressure vacuum port, 5-Cylinder, 6-Composite screw, 7-Mel flow line, 8-Mel flow pump, 9-Metering pump, 10-Spinning box, 11-Spinning assembly. Detailed Implementation

[0049] The technical solutions of the embodiments 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. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0050] Example 1

[0051] Preparation of composite modifier:

[0052] Using low-quality silk and cocoons as raw materials, the raw materials were dried at 50℃ for 12 hours, and 1.0% by mass of sarapeptidase was added. The mixture was then enzymatically hydrolyzed in a buffer solution at 45℃ and pH 7.0 for 2 hours.

[0053] Add 3% by mass of 2,3-epoxypropyltrimethylammonium chloride to the enzymatically hydrolyzed silkworm protein solution and react at 50°C for 2 hours. Then, spray dry the modified silkworm protein solution (inlet air temperature 160°C, outlet air temperature 70°C) to make powder, and then grind it with an ultra-micro pulverizer to control the particle size at 1.2 μm.

[0054] Modified silk powder was uniformly dispersed in a prepared ZIF-8 precursor solution. The reaction was carried out by solvothermal method at a temperature of 110℃ for 10 hours. After the reaction was completed, the mixture was naturally cooled to room temperature. The product was then separated by centrifugation and washed with deionized water. The product was dried overnight in a vacuum oven at 50℃ to prepare silk protein powder / MOF composite material.

[0055] Silkworm protein powder / MOF composite material was dispersed in tributyl citrate, and antioxidant 1010, PCL graft copolymer and coupling agent KH560 were added. The mixture was stirred evenly to prepare a silkworm protein powder / MOF composite emulsion with a mass fraction of 20%. Among them, the amount of antioxidant 1010 added was 1% of the mass of silkworm protein powder, the number average molecular weight of PCL graft copolymer was 7000 and the amount added was 4% of the mass of silkworm protein powder, and the amount of coupling agent KH560 added was 0.3% of the mass of silkworm protein powder.

[0056] Online Additive Melt Spinning: Polyvinyl chloride (PVC) melt spinning is performed using a multi-frequency high-frequency shear melt extrusion system. The system is equipped with a multi-screw system and an online additive system. Silkworm protein powder / MOF composite emulsion, prepared through an online additive process, is added to the PVC melt. After thorough mixing, spinning is performed to produce room-temperature and room-pressure dyeable PVC fibers. The amount of silkworm protein powder / MOF composite emulsion added is 10% of the PVC mass. Screw zone temperatures are 150℃ in zone 1, 170℃ in zone 2, 175℃ in zone 3, 175℃ in zone 4, and 175℃ in the spinning box. The spinning speed is 800 m / min, the draw ratio is 3, and the setting temperature is 65℃.

[0057] Example 2

[0058] Preparation of composite modifier:

[0059] Waste silk products recycled from the market were used as raw materials. They were shredded into fragments of about 3mm using a shredder. The raw materials were dried at 50℃ for 12 hours. Then, 0.5% by mass of Aspergillus oryzae protease was added, and the mixture was enzymatically hydrolyzed in a buffer solution at 55℃ and pH 7.2 for 4 hours.

[0060] Add 5% by mass of 2,3-epoxypropyltrimethylammonium chloride to the enzymatically hydrolyzed silkworm protein solution and react at 50°C for 2 hours. Then, spray dry the modified silkworm protein solution (inlet air temperature 160°C, outlet air temperature 70°C) to make powder, and then grind it with an ultra-micro pulverizer to control the particle size at 0.8μm.

[0061] Modified silk powder was uniformly dispersed in a prepared UiO-67 precursor solution. The reaction was carried out by solvothermal method at a temperature of 120℃ for 12 hours. After the reaction was completed, the mixture was naturally cooled to room temperature. The product was then separated by centrifugation and washed with deionized water. The product was dried overnight in a vacuum oven at 60℃ to prepare silk protein powder / MOF composite material.

[0062] Silkworm protein powder / MOF composite material was dispersed in tributyl citrate, and antioxidant 1010, PCL graft copolymer and coupling agent KH560 were added. The mixture was stirred evenly to prepare a silkworm protein powder / MOF composite emulsion with a mass fraction of 30%. Among them, the amount of antioxidant 1010 added was 1.5% of the mass of silkworm protein powder, the number average molecular weight of PCL graft copolymer was 8000 and the amount added was 6% of the mass of silkworm protein powder, and the amount of coupling agent KH560 added was 0.5% of the mass of silkworm protein powder.

[0063] Online Additive Melt Spinning: Polyvinyl chloride (PVC) melt spinning is performed using a multi-screw high-frequency shear melt extrusion system. The system includes a multi-screw system and an online additive system. Silkworm protein powder / MOF composite emulsion, prepared via an online additive process, is added to the PVC melt. After thorough mixing, spinning is performed to produce room-temperature and room-pressure dyeable PVC fibers. The amount of silkworm protein powder / MOF composite emulsion added is 10% of the PVC mass. Screw zone temperatures are 170℃, 180℃, 180℃, and 180℃ in each zone; the spinning box temperature is 185℃; the spinning speed is 800 m / min; the draw ratio is 5; and the setting temperature is 65℃.

[0064] Comparative Example 1 (without MOF)

[0065] Preparation of composite modifier:

[0066] Using low-quality silk and cocoons as raw materials, the raw materials were dried at 50℃ for 12 hours, and 1.0% by mass of sarapeptidase was added. The mixture was then enzymatically hydrolyzed in a buffer solution at 45℃ and pH 7.0 for 2 hours.

[0067] Add 3% by mass of 2,3-epoxypropyltrimethylammonium chloride to the enzymatically hydrolyzed silkworm protein solution and react at 50°C for 2 hours. Then, spray dry the modified silkworm protein solution (inlet air temperature 160°C, outlet air temperature 70°C) to make powder, and then grind it with an ultra-micro pulverizer to control the particle size at 1.2 μm.

[0068] Silkworm protein powder was dispersed in tributyl citrate, and antioxidant 1010, PCL graft copolymer and coupling agent KH560 were added and stirred evenly to prepare a silkworm protein powder emulsion with a mass fraction of 20%. Among them, the amount of antioxidant 1010 added was 1% of the mass of silkworm protein powder, the number average molecular weight of PCL graft copolymer was 7000 and the amount added was 4% of the mass of silkworm protein powder, and the amount of coupling agent KH560 added was 0.3% of the mass of silkworm protein powder.

[0069] Online Additive Melt Spinning: Polyvinyl chloride (PVC) melt spinning is performed using a multi-frequency high-frequency shear melt extrusion system. The system is equipped with a multi-screw system and an online additive system. Silkworm protein powder emulsion, prepared through an online additive process, is added to the PVC melt. After thorough mixing, spinning is performed to produce room-temperature and room-pressure dyeable PVC fibers. The amount of silkworm protein powder emulsion added is 10% of the PVC mass. Screw zone temperatures are 150℃ in zone 1, 170℃ in zone 2, 175℃ in zone 3, 175℃ in zone 4, and 175℃ in the spinning box. The spinning speed is 800 m / min, the draw ratio is 3, and the setting temperature is 65℃.

[0070] Comparative Example 2 (without enzymatic hydrolysis)

[0071] Preparation of composite modifier:

[0072] Using low-quality silk and silkworm cocoons as raw materials, a pulverizer is used to pulverize the raw materials into powder with a size of about 1mm;

[0073] The pulverized silk powder raw material was dispersed in deionized water, and 3% by mass of 2,3-epoxypropyltrimethylammonium chloride was added. The mixture was reacted at 50°C for 2 hours. The modified silk powder solution was dried in an oven and then ground by an ultra-micro pulverizer to control the particle size at 1.2 μm.

[0074] Modified silk powder was uniformly dispersed in a prepared ZIF-8 precursor solution. The reaction was carried out by solvothermal method at a temperature of 110℃ for 10 hours. After the reaction was completed, the mixture was naturally cooled to room temperature. The product was then separated by centrifugation and washed with deionized water. The product was dried overnight in a vacuum oven at 50℃ to prepare silk powder / MOF composite material.

[0075] Silk powder / MOF composite material was dispersed in tributyl citrate, and antioxidant 1010, PCL graft copolymer and coupling agent KH560 were added. The mixture was stirred evenly to prepare a silk powder / MOF composite emulsion with a mass fraction of 20%. The amount of antioxidant 1010 added was 1% of the mass of silk powder, the number average molecular weight of PCL graft copolymer was 7000 and the amount added was 4% of the mass of silk powder, and the amount of coupling agent KH560 added was 0.3% of the mass of silk powder.

[0076] Online Additive Melt Spinning: Polyvinyl chloride (PVC) melt spinning is performed using a multi-frequency high-frequency shear melt extrusion system. The system is equipped with a multi-screw system and an online additive system. Silk powder / MOF composite emulsion, prepared through an online additive process, is added to the PVC melt. After thorough mixing, spinning is performed to produce room-temperature and atmospheric-pressure dyeable PVC fibers. The amount of silk powder / MOF composite emulsion added is 10% of the PVC mass. Screw zone temperatures are 150℃ in zone 1, 170℃ in zone 2, 175℃ in zone 3, 175℃ in zone 4, and 175℃ in the spinning box. The spinning speed is 800 m / min, the draw ratio is 3, and the setting temperature is 65℃.

[0077] Comparative Example 3 (without GTA modification)

[0078] Preparation of composite modifier:

[0079] Using low-quality silk and cocoons as raw materials, the raw materials were dried at 50℃ for 12 hours, and 1.0% by mass of sarapeptidase was added. The mixture was then enzymatically hydrolyzed in a buffer solution at 45℃ and pH 7.0 for 2 hours.

[0080] The enzymatically hydrolyzed silkworm protein solution was spray-dried (inlet air temperature 160℃, outlet air temperature 70℃) to form powder, which was then ground by an ultra-micro pulverizer to control the particle size at 1.2μm.

[0081] Silk powder was uniformly dispersed in a prepared ZIF-8 precursor solution. The reaction was carried out by solvothermal method at a temperature of 110℃ for 10 hours. After the reaction was completed, the mixture was naturally cooled to room temperature. The product was then separated by centrifugation and washed with deionized water. The product was dried overnight in a vacuum oven at 50℃ to prepare silk protein powder / MOF composite material.

[0082] Silkworm protein powder / MOF composite material was dispersed in tributyl citrate, and antioxidant 1010, PCL graft copolymer and coupling agent KH560 were added. The mixture was stirred evenly to prepare a silkworm protein powder / MOF composite emulsion with a mass fraction of 20%. Among them, the amount of antioxidant 1010 added was 1% of the mass of silkworm protein powder, the number average molecular weight of PCL graft copolymer was 7000 and the amount added was 4% of the mass of silkworm protein powder, and the amount of coupling agent KH560 added was 0.3% of the mass of silkworm protein powder.

[0083] Online Additive Melt Spinning: Polyvinyl chloride (PVC) melt spinning is performed using a multi-frequency high-frequency shear melt extrusion system. The system is equipped with a multi-screw system and an online additive system. Silkworm protein powder / MOF composite emulsion, prepared through an online additive process, is added to the PVC melt. After thorough mixing, spinning is performed to produce room-temperature and room-pressure dyeable PVC fibers. The amount of silkworm protein powder / MOF composite emulsion added is 10% of the PVC mass. Screw zone temperatures are 150℃ in zone 1, 170℃ in zone 2, 175℃ in zone 3, 175℃ in zone 4, and 175℃ in the spinning box. The spinning speed is 800 m / min, the draw ratio is 3, and the setting temperature is 65℃.

[0084] [The design differs from Example 1 in that it does not involve GTA modification, in order to demonstrate the necessity of modification].

[0085] Comparative Example 4 (without PCL)

[0086] Compared to Example 1, this comparative example only omits the addition of PCL graft copolymer during the preparation of the silkworm protein powder / MOF composite emulsion, illustrating the importance of dispersing silkworm protein powder / MOF in the PVC matrix.

[0087] Preparation of composite modifier:

[0088] Using low-quality silk and cocoons as raw materials, the raw materials were dried at 50℃ for 12 hours, and 1.0% by mass of sarapeptidase was added. The mixture was then enzymatically hydrolyzed in a buffer solution at 45℃ and pH 7.0 for 2 hours.

[0089] Add 3% by mass of 2,3-epoxypropyltrimethylammonium chloride to the enzymatically hydrolyzed silkworm protein solution and react at 50°C for 2 hours. Then, spray dry the modified silkworm protein solution (inlet air temperature 160°C, outlet air temperature 70°C) to make powder, and then grind it with an ultra-micro pulverizer to control the particle size at 1.2 μm.

[0090] Modified silk powder was uniformly dispersed in a prepared ZIF-8 precursor solution. The reaction was carried out by solvothermal method at a temperature of 110℃ for 10 hours. After the reaction was completed, the mixture was naturally cooled to room temperature. The product was then separated by centrifugation and washed with deionized water. The product was dried overnight in a vacuum oven at 50℃ to prepare silk protein powder / MOF composite material.

[0091] The silkworm protein powder / MOF composite material was dispersed in tributyl citrate, and antioxidant 1010 and coupling agent KH560 were added and stirred evenly to prepare a silkworm protein powder / MOF composite emulsion with a mass fraction of 20%; wherein, the amount of antioxidant 1010 added was 1% of the mass of silkworm protein powder, and the amount of coupling agent KH560 added was 0.3% of the mass of silkworm protein powder.

[0092] Online Additive Melt Spinning: Polyvinyl chloride (PVC) melt spinning is performed using a multi-frequency high-frequency shear melt extrusion system. The system is equipped with a multi-screw system and an online additive system. Silkworm protein powder / MOF composite emulsion, prepared through an online additive process, is added to the PVC melt. After thorough mixing, spinning is performed to produce room-temperature and room-pressure dyeable PVC fibers. The amount of silkworm protein powder / MOF composite emulsion added is 10% of the PVC mass. Screw zone temperatures are 150℃ in zone 1, 170℃ in zone 2, 175℃ in zone 3, 175℃ in zone 4, and 175℃ in the spinning box. The spinning speed is 800 m / min, the draw ratio is 3, and the setting temperature is 65℃.

[0093] Comparative Example 5

[0094] The PVC fibers were commercially available, and their mechanical and dyeing properties were directly tested.

[0095] Performance testing:

[0096] Spinning continuity: During the spinning process, the number of fiber breaks per 10,000 meters of fiber is recorded, the fiber breakage rate is calculated, and the spinning continuity is calculated based on the fiber breakage rate.

[0097] Dyeing performance testing: mainly evaluates the types of dyes that can be applied, the dyeing rate, and the color fastness.

[0098] Tensile strength test: The tensile strength of the fiber is tested using a universal testing machine.

[0099] Heat shrinkage rate test: The heat shrinkage rate of the fiber is tested using a dry heat shrinkage tester for chemical fiber filaments.

[0100] Table 1. Fiber performance parameters corresponding to different embodiments

[0101]

[0102] Analysis and Conclusion:

[0103] Examples 1 and 2, and Comparative Examples 1 to 4, all successfully prepared PVC fibers that can be dyed at room temperature and pressure. Compared with conventional PVC fibers produced by traditional technology, the PVC fibers produced by the present invention can be dyed with acid dyes, reactive dyes, cationic dyes and disperse dyes under room temperature and pressure conditions, while traditional PVC fibers can only be dyed with disperse dyes.

[0104] Comparative Example 1 (without MOF modification): The silk protein powder lacking MOF encapsulation protection has limited heat resistance. During the spinning process, the partial decomposition of the silk protein powder leads to a decrease in spinning continuity and a reduction in fiber breaking strength.

[0105] Comparative Example 2 (without enzymatic hydrolysis) prepared silk powder raw materials with larger particle size through simple mechanical crushing. The material surface had few active groups, resulting in poor effects of subsequent GTA grafting and MOF composite modification. The heat resistance and dispersibility were reduced, leading to a decrease in fiber processing and performance.

[0106] Comparative Example 3 (unmodified) silk fibroin powder, without GTA modification, exhibited significantly reduced heat resistance, affecting subsequent blending and spinning processes, decreasing spinning continuity, and lowering fiber breaking strength. The breakage rate increased significantly, demonstrating the crucial role of DOP plasticization in spinning stability. The prepared spunlace fabric had a soft hand feel.

[0107] Comparative Example 4 (without PCL): The absence of PCL in the PVC resin blend system reduced the compatibility and dispersibility of the silkworm protein powder / MOF composite material in the PVC resin, resulting in decreased spinning performance and fiber mechanical properties. Simultaneously, the poor dispersion of the composite modifier in the resin matrix also limited the dyeing performance of the fiber.

[0108] Those skilled in the art should understand that the technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments have been 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.

[0109] The above embodiments are merely illustrative of several implementation methods of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A method for preparing room-temperature and room-pressure dyeable PVC fiber, characterized in that, Includes the following steps: 1) Add neutral protease to dried silk raw materials and enzymatically hydrolyze them in a buffer solution at 40-50℃ and pH 6.5-8.0 for 1-4 hours to obtain a silk protein solution; 2) Add 2,3-epoxypropyltrimethylammonium chloride to the silk protein solution and react it at 55-65℃ for 2-5 hours to obtain a modified silk protein solution. Spray dry and grind the modified silk protein solution to obtain modified silk protein with a particle size of 0.5-2μm; 3) Disperse the modified silk protein in MOF precursor liquid and prepare silk protein powder / MOF composite material by solvothermal method; 4) Disperse the silk protein powder / MOF composite material in tributyl citrate and add antioxidant, PCL graft copolymer and coupling agent to prepare silk protein powder / MOF composite emulsion. Antioxidant 1010 is selected as the antioxidant. 5) The silkworm protein powder / MOF composite emulsion is added to the PVC melt during the melt spinning process of PVC, and after thorough mixing, it is spun to obtain room temperature and pressure dyeable PVC fiber. The fiber is dyed using any or a combination of acid dyes, reactive dyes and / or cationic dyes at room temperature and pressure.

2. The method for preparing room-temperature and room-pressure dyeable PVC fiber according to claim 1, characterized in that, Silk raw materials are selected from one or a combination of silkworm silk, silkworm cocoons and waste silk products.

3. The method for preparing room-temperature and room-pressure dyeable PVC fiber according to claim 1, characterized in that, The neutral protease is selected from one or a combination of Serratia protease, Seraitia protease, Aspergillus oryzae protease, and Rhizopus protease.

4. The method for preparing room-temperature and room-pressure dyeable PVC fiber according to claim 1, characterized in that, The mass fraction of neutral protease is 0.5%~1.2%, and the degree of enzymatic hydrolysis of silk in the silk protein solution is 5%~15%.

5. The method for preparing room-temperature and room-pressure dyeable PVC fiber according to claim 1, characterized in that, The MOF can be any one of ZIF-8, UiO-66, UiO-67, MOF-5, ZIF-8@Mxene, or MOF-5@graphene.

6. The method for preparing room-temperature and room-pressure dyeable PVC fiber according to claim 1, characterized in that, The coupling agent chosen was KH560, and the number average molecular weight of the PCL graft copolymer was 5000-8000.

7. The method for preparing room-temperature and room-pressure dyeable PVC fiber according to claim 1, characterized in that, The mass fraction of the silkworm protein powder / MOF composite emulsion is 5-25%, wherein the amount of antioxidant added is 0.5-2% of the mass of the silkworm protein powder / MOF composite material, the amount of added antioxidant is 3-6% of the mass of the silkworm protein powder / MOF composite material, and the amount of coupling agent added is 0.5-5% of the mass of the silkworm protein powder / MOF composite material.

8. The method for preparing room-temperature and room-pressure dyeable PVC fiber according to claim 1, characterized in that, The spinning conditions are as follows: screw temperature in each zone is 150-180℃, spinning temperature is 170-190℃, and spinning speed is 800-2300m / min.

9. A type of PVC fiber that can be dyed at room temperature and pressure, characterized in that, include: PVC fiber, wherein the PVC fiber contains a modified silk protein powder / MOF composite material, the modified silk protein powder / MOF composite material being modified silk protein powder encapsulated by MOF material, and is prepared by the method for preparing room temperature and pressure dyeable PVC fiber according to any one of claims 1 to 8.

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