Bicomponent superhydrophilic fiber with core-sheath structure and preparation method thereof

Abstract

The application provides a kind of bicomponent super-hydrophilic fiber of skin-core structure and its preparation method, belongs to the field of composite fiber preparation, non-water-soluble PET is used as core layer material, nano SiO2 is uniformly mixed with water-soluble PET as skin layer material, and SiO2 / PET fiber of skin-core structure is prepared by melt spinning;Then, SiO2 / PET fiber is soaked in 80-95 DEG C hot water, is treated for 4-6 h by using three-stage gradient temperature control process, to dissolve water-soluble PET in skin layer, obtain bicomponent super-hydrophilic fiber.The bicomponent super-hydrophilic fiber provided in the application adopts skin-core structure, the skin layer is hydrophilic phase, the surface has a plurality of nanopores with pore size of 80-250 nm, bosses with height of 10-50 nm, pore depth is 1-3 um, and the overall open porosity is 30-65%, which ensures the exposure of hydrophilic nanoparticles (SiO2), the static water contact angle is ≤5° (completely wet within 2 s), has excellent super-hydrophilic and rapid moisture conducting performance, and maintains good mechanical strength and washing resistance.

Description

Technical Field

[0001] This invention relates to the field of composite fiber preparation technology, specifically to a core-sheath structure of a two-component superhydrophilic fiber and its preparation method. Background Technology

[0002] Superhydrophilic fibers are functional fiber materials that have a water contact angle of less than 5° and can achieve complete wetting in a very short time. They have broad application prospects in medical dressings, sportswear, filtration and separation, oil-water separation and other fields.

[0003] For superhydrophilic fibers, existing two-component technologies have the following shortcomings:

[0004] (1) Low utilization rate of functional components: The cortex of traditional bicomponent fibers is often a continuous and dense structure. The hydrophilic functional components are covered by the polymer matrix and cannot be fully exposed on the fiber surface, resulting in unsatisfactory hydrophilic effect.

[0005] (2) Simple surface structure: lack of effective micro-nano composite rough structure design, making it difficult to achieve the synergistic effect of capillary effect and surface energy, and failing to meet the superhydrophilic standard (contact angle <5°).

[0006] (3) Inefficient process parameters: Existing preparation processes lack precise control over key parameters such as temperature, time, and draw ratio, resulting in uneven fiber structure and poor performance reproducibility. In particular, the use of a single temperature treatment during the removal of water-soluble components can easily lead to structural collapse or incomplete removal.

[0007] (4) Difficulty in balancing performance: In the pursuit of superhydrophilic properties, the mechanical strength, dimensional stability and durability of the fiber are often sacrificed, which limits its practical application.

[0008] Therefore, there is an urgent need to develop a novel method for preparing bicomponent superhydrophilic fibers. Through reasonable structural design and precise process control, a stable micro-nano composite porous structure can be constructed on the fiber surface to fully expose the hydrophilic functional components, thereby obtaining functional fiber materials with excellent superhydrophilic properties, mechanical properties and durability. Summary of the Invention

[0009] In view of the technical problems existing in the background art, this application provides a method for preparing a core-sheath structured bicomponent superhydrophilic fiber. The method uses a non-water-soluble PET substrate (PET masterbatch) as the core material and a SiO2 / water-soluble PET composite masterbatch as the sheath material. The core and sheath materials are melt-spun in a certain proportion. By controlling the melting temperature difference between the sheath and core layers, the interfacial stability and fiber forming accuracy are improved. By controlling the speed difference between the sheath screw and the core screw, the tensile strength of the fiber is improved, thus preparing SiO2 / PET fiber. Then, the SiO2 / PET fiber is immersed in hot water at 80-95℃ and treated with a three-stage gradient temperature control process for 4-6 hours to dissolve the water-soluble PET in the sheath, obtaining a core-sheath structured bicomponent superhydrophilic fiber.

[0010] The bicomponent superhydrophilic fiber prepared in this application has several pores with a diameter of 80-250 nm, protrusions with a height of 10-50 nm, and a pore depth of 1-3 μm. The open porosity of the surface of the bicomponent superhydrophilic fiber is 30-65%, which significantly increases the roughness of the fiber skin.

[0011] In a first aspect, embodiments of this application provide a method for preparing a core-sheath structured bicomponent superhydrophilic fiber, comprising the following steps:

[0012] S1. Terephthalic acid, isophthalic acid, ethylene glycol, and neopentyl glycol are placed in a reaction vessel in a preset ratio, nitrogen gas is introduced, and pressure is applied to carry out an esterification reaction. After the esterification reaction is completed, sodium bis(hydroxyethyl) isophthalate-5-sulfonate is added to polyethylene glycol to carry out a polycondensation reaction. After the reaction is completed, a water-soluble polyester material is obtained, which is then granulated to obtain a water-soluble PET masterbatch.

[0013] S2, uniformly mix nano-SiO2 particles with the water-soluble PET masterbatch obtained in step S1, melt extrude and granulate to obtain SiO2 / water-soluble PET composite masterbatch;

[0014] S3, PET masterbatch and SiO2 / water-soluble PET composite masterbatch obtained in step S2 are added to the core layer and sheath layer feed inlets respectively, and SiO2 / PET fiber with sheath core structure is prepared by a two-component melt spinning machine;

[0015] S4, the SiO2 / PET fiber with a core-sheath structure prepared in step S3 is immersed in hot water at 80-95℃ and treated with a three-stage gradient temperature control process for 4-6 h to dissolve the water-soluble PET in the sheath layer, thereby obtaining a bicomponent superhydrophilic fiber; the three-stage gradient temperature control process specifically involves treating the SiO2 / PET fiber at 80-85℃ for ah, at 85-90℃ for bh, and at 90-95℃ for ch, where a:b:c=(1-2):(1-1.5):1.

[0016] Furthermore, the value of a ranges from 1 to 2h.

[0017] Furthermore, the heating rate during the three-stage gradient temperature control process is 3-5℃ / h.

[0018] Furthermore, in step S2, the content of nano-SiO2 particles in the SiO2 / water-soluble PET composite masterbatch is 5-14 wt%.

[0019] Furthermore, in step S3, the flow rate ratio of the SiO2 / water-soluble PET composite masterbatch to the PET masterbatch is 1:(1.5-4).

[0020] Furthermore, the degree of sulfonation of water-soluble PET is 10-15 mol.

[0021] Furthermore, the particle size of the nano-SiO2 particles is 10-35 nm.

[0022] Furthermore, in step S3, the intrinsic viscosity of the PET masterbatch is 0.68-0.75 dL / g.

[0023] Secondly, embodiments of this application provide a core-sheath structure of a bicomponent superhydrophilic fiber, which is prepared using any of the aforementioned methods.

[0024] Furthermore, the surface of the bicomponent superhydrophilic fiber has several pores with a diameter of 80-250 nm, protrusions with a height of 10-50 nm, and a pore depth of 1-3 μm; the open porosity of the surface of the bicomponent superhydrophilic fiber is 30-65%.

[0025] The beneficial effects of this application are as follows:

[0026] This application provides a method for preparing a core-sheath structured bicomponent superhydrophilic fiber. A non-water-soluble PET substrate (PET masterbatch) is used as the core material, and a SiO2 / water-soluble PET composite masterbatch is used as the sheath material. The core and sheath materials are melt-spun in a certain proportion to obtain SiO2 / PET fibers. Then, the SiO2 / PET fibers are immersed in hot water at 80-95℃ and treated with a three-stage gradient temperature control process for 4-6 hours. Hot water immersion dissolves the water-soluble PET in the sheath. Through the three-stage gradient temperature control process, the weak interface between the water-soluble PET and SiO2 in the fiber sheath dissolves first, causing pores to appear around the SiO2 particles on the surface of the bicomponent fiber sheath. As the treatment temperature increases, the pores around the SiO2 particles gradually enlarge, increasing the surface roughness. The treatment time (a, b, c) at different temperatures determines the height of the bosses, the depth of the pores, and the diameter of the pores. As the roughness of the hydrophilic surface increases, the hydrophilicity of the bicomponent is improved, resulting in superhydrophilic fibers.

[0027] The bicomponent superhydrophilic fiber prepared in this application has several pores with a diameter of 80-250 nm, protrusions with a height of 10-50 nm, and a pore depth of 1-3 μm on its surface. The open porosity of the surface of this bicomponent superhydrophilic fiber is 30-65%, which significantly increases the roughness of the fiber skin. These characteristics give the bicomponent superhydrophilic fiber excellent superhydrophilic properties, mechanical properties, and durability. After 50 standard washes, the SiO2 particle retention rate reaches 99%, and the hydrophilicity remains completely wetted within 5 seconds after 50 standard washes.

[0028] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0029] To more clearly illustrate the technical solution of this application, the accompanying drawings used in this application will be briefly described below. Obviously, the drawings described below are merely some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without any creative effort.

[0030] Figure 1 This is a SEM image of the core-sheath structured bicomponent superhydrophilic fiber prepared in Example 1.

[0031] Figure 2This is a schematic diagram of the bicomponent superhydrophilic fiber with a core-sheath structure according to this application. In the diagram, the light blue area represents water-soluble PET, the yellow area represents SiO2, and the dark blue area represents the morphology of droplets on the fiber surface.

[0032] Figure 3 The image shows the hydrophilic effect of the core-sheath structured bicomponent superhydrophilic fiber prepared in Example 1.

[0033] Figure 4 This is a SEM image of the core-sheath structured bicomponent superhydrophilic fiber prepared in Example 2.

[0034] Figure 5 This is a diagram illustrating the hydrophilic effect of the core-sheath structured bicomponent superhydrophilic fiber prepared in Comparative Example 1. Detailed Implementation

[0035] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0037] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0038] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0039] In the description of the embodiments of this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application according to the specific circumstances.

[0040] In existing technologies, the main methods for preparing hydrophilic fibers include surface chemical modification, blending modification, and micro / nano structure construction. Although the blending modification method is simple, the hydrophilic components are unevenly distributed inside the fiber, with most of them being embedded in the matrix and unable to play a role, resulting in low hydrophilic efficiency, large addition amounts, and severe deterioration of mechanical properties.

[0041] To address the aforementioned technical problems, this application provides a method for preparing a core-sheath structured bicomponent superhydrophilic fiber. The method uses a non-water-soluble PET substrate as the core material and a SiO2 / water-soluble PET composite masterbatch as the sheath material. The core and sheath materials are melt-spun in a specific ratio. Interface stability and fiber forming precision are improved by controlling the melting temperature difference between the sheath and core layers. Tensile strength is enhanced by controlling the speed difference between the sheath screw and the core screw. This process yields SiO2 / PET fibers. The SiO2 / PET fibers are then immersed in hot water at 80-95℃ and treated with a three-stage gradient temperature control process for 4-6 hours to dissolve the water-soluble PET in the sheath, resulting in a core-sheath structured bicomponent superhydrophilic fiber.

[0042] In a first aspect, embodiments of this application provide a method for preparing a core-sheath structured bicomponent superhydrophilic fiber, comprising the following steps:

[0043] S1. Terephthalic acid, isophthalic acid, ethylene glycol, and neopentyl glycol are placed in a reaction vessel in a preset ratio, nitrogen gas is introduced, and pressure is applied to carry out an esterification reaction. After the esterification reaction is completed, sodium bis(hydroxyethyl) isophthalate-5-sulfonate is added to polyethylene glycol for a polycondensation reaction. After the reaction is completed, a water-soluble polyester material is obtained, which is then granulated to obtain a water-soluble PET masterbatch. The degree of sulfonation of the water-soluble PET is 10-15 mol.

[0044] For details on the preparation process of water-soluble polyester materials, please refer to the text with publication number CN118271585A, which will not be repeated here.

[0045] S2, uniformly mix nano-SiO2 particles with the water-soluble PET masterbatch obtained in step S1, melt extrude and granulate to obtain SiO2 / water-soluble PET composite masterbatch;

[0046] The particle size of the nano-SiO2 particles is 10-35 nm.

[0047] The intrinsic viscosity of PET masterbatch is 0.68-0.75 dL / g.

[0048] In the SiO2 / water-soluble PET composite masterbatch, the content of nano-SiO2 particles is 5-14wt%.

[0049] S3, PET masterbatch and SiO2 / water-soluble PET masterbatch obtained in step S2 are added to the core layer and sheath layer feed inlets respectively, and SiO2 / PET fiber with sheath core structure is prepared by a two-component melt spinning machine;

[0050] The flow rate ratio of SiO2 / water-soluble PET composite masterbatch to PET masterbatch is 1:(1.5-4).

[0051] Experiments show that PET has higher strength than water-soluble PET. Increasing the core layer ratio can improve the tensile strength of the fiber; increasing the sheath layer ratio effectively increases the number of silica particles per unit area. After a three-stage gradient temperature control treatment, the surface roughness of the sheath layer increases, thereby improving hydrophilicity, but at the same time reducing the tensile strength of the fiber. Therefore, it is necessary to adjust the core-sheath flow ratio and control the core-sheath thickness to obtain fibers that have both tensile strength and good hydrophilicity.

[0052] In this embodiment, the melt spinning process includes a material initial melting stage, a plasticizing stage, a core-sheath mixing stage, and a die stage. In the aforementioned stages, the melting temperature difference between the sheath and the core is 80-90°C.

[0053] Specifically, the skin temperature in the initial melting stage is set at 200-210℃, and the core temperature is set at 240-250℃ to ensure initial melting of the material and prevent clogging of the feed inlet; in the plasticizing stage, the skin temperature is set at 175-185℃ for full melting, and the core temperature is set at 260-270℃ to reduce melt viscosity; in the skin-core mixing stage, the skin temperature is set at 180-190℃, and the core temperature is set at 270-280℃ to maintain the interfacial stability of the two-phase melt; in the die stage, the skin temperature is set at 185-195℃, and the core temperature is set at 275-285℃ to improve melt flow uniformity and fiber forming accuracy.

[0054] In this embodiment, the rotational speed difference between the sheath screw and the core screw during melt spinning is 20-30 rpm to induce shear orientation and improve fiber tensile strength. Furthermore, the sheath screw is accelerated by 5 rpm every 2 minutes to reach the target speed, and the core screw is accelerated by 10 rpm every 2 minutes to reach the target speed.

[0055] In this embodiment of the application, the metering pump speed ratio of the sheath to the core layer during melt spinning is (1.2-1.5):1, so that the sheath thickness reaches 15-20% of the total fiber diameter.

[0056] In this embodiment of the application, the die pressure of the outer layer is 3-5 MPa and the die pressure of the core layer is 8-12 MPa during melt spinning to avoid melt rupture or interface peeling.

[0057] S4. The SiO2 / PET fibers with a core-sheath structure prepared in step S3 are immersed in hot water at 80-95℃ and treated with a three-stage gradient temperature control process for 4-6 hours to dissolve the water-soluble PET in the sheath and obtain a bicomponent superhydrophilic fiber. The three-stage gradient temperature control process is as follows: SiO2 / PET fibers are treated at 80-85℃ for ah, at 85-90℃ for bh, and at 90-95℃ for ch, where a:b:c=(1-2):(1-1.5):1.

[0058] The value of a ranges from 1 to 2h.

[0059] The heating rate during the three-stage gradient temperature control process is 3-5℃ / h.

[0060] Hot water soaking dissolves the water-soluble PET in the fiber sheath. Using a three-stage gradient temperature control process, the weakest interface between the water-soluble PET and SiO2 in the fiber sheath dissolves first, creating pores around the SiO2 particles on the surface of the bicomponent fiber sheath. As the processing temperature increases, the pores around the SiO2 particles gradually enlarge, increasing the surface roughness. The processing times at different temperatures (a, b, c) determine the height of the bosses, the depth of the pores, and the diameter of the pores. With the increased roughness of the hydrophilic surface, the hydrophilicity of the bicomponent is enhanced, resulting in superhydrophilic fibers.

[0061] Secondly, this application also provides a core-sheath structured bicomponent superhydrophilic fiber, prepared using any of the aforementioned technical solutions.

[0062] The surface of this bicomponent superhydrophilic fiber has several pores with a diameter of 80-250 nm, protrusions with a height of 10-50 nm, and a pore depth of 1-3 μm. The open porosity of the surface of this bicomponent superhydrophilic fiber is 30-65%, which significantly increases the roughness of the fiber skin.

[0063] The following are some specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0064] Example 1

[0065] Example 1 provides a method for preparing a core-sheath structured bicomponent superhydrophilic fiber, comprising the following steps:

[0066] S1. Terephthalic acid, isophthalic acid, ethylene glycol, and neopentyl glycol are placed in a reaction vessel in a molar ratio of 1:1:1.6:0.8. Nitrogen gas is introduced and pressure is applied for esterification reaction. The esterification reaction temperature is 260℃ and the pressure is 350kPa. After the esterification reaction is completed, sodium diethyl isophthalate-5-sulfonate and polyethylene glycol are added for polycondensation reaction under vacuum at a temperature of 280℃ for 3 hours. The amount of sodium diethyl isophthalate-5-sulfonate added is 10% of the mass of terephthalic acid, and the amount of polyethylene glycol added is 15% of the mass of terephthalic acid. After the reaction is completed, a water-soluble polyester material for melt spinning is obtained. Granulation is then performed to obtain a water-soluble PET masterbatch.

[0067] S2, nano-SiO2 particles (average particle size 50 nm) are uniformly mixed with the water-soluble PET masterbatch obtained in step S1 (sulfonation degree 12 mol%, melt index 35 g / min), and then melt-extruded and granulated to obtain SiO2 / water-soluble PET composite masterbatch; the mass ratio of nano-SiO2 particles to water-soluble PET masterbatch is 7:43. That is, the content of nano-SiO2 particles in the SiO2 / water-soluble PET composite masterbatch is 14 wt%.

[0068] S3, PET masterbatch (core material, viscosity of 0.72dL / g) and SiO2 / water-soluble PET masterbatch (skin material) obtained in step S2 are added to the core and skin feed ports respectively. The skin material and core material are melted at a flow ratio of 1:3 and then spun to obtain SiO2 / PET fiber with a skin-core structure. At this time, nano-SiO2 is uniformly distributed in the skin.

[0069] During the melt spinning process, the initial melting stage of the material is set with the skin temperature at 225℃ and the core temperature at 245℃; during the plasticizing stage, the skin temperature is set at 245℃ and the core temperature at 265℃; during the skin-core mixing stage, the temperature is adjusted to 250℃ for the skin and 275℃ for the core; and during the die stage, the temperature is further adjusted to 255℃ for the skin and 280℃ for the core.

[0070] The outer layer screw speed is set to 25 rpm, and increased by 5 rpm every 2 minutes to reach the target speed. The core layer screw speed is set to 50 rpm, and increased by 10 rpm every 2 minutes to reach the target speed.

[0071] The metering pump speed ratio between the skin layer and the core layer is 1.4:1, the die pressure of the skin layer is 4MPa, the die pressure of the core layer is 10MPa, the draw ratio of the skin layer is 2.8:1, and the draw ratio of the core layer is 3.5:1.

[0072] S4. The prepared SiO2 / PET fibers were immersed in hot water at 85℃ and treated with a three-stage gradient temperature control process of 85℃→90℃→95℃ for 6 hours to dissolve the water-soluble PET in the sheath layer, thus obtaining a bicomponent superhydrophilic fiber with a sheath-core structure. Specifically, the three-stage gradient temperature control process involved treating the SiO2 / PET fibers at 85℃ for 2 hours, at 90℃ for 2 hours, and at 95℃ for 2 hours, with a heating rate of 5℃ / h.

[0073] Please see Figures 1 to 2 As shown, the surface of the bicomponent superhydrophilic fiber prepared in Example 1 has several pores with a diameter of 80-250 nm, protrusions with a height of 10-50 nm, and a pore depth of 1-3 μm. The porosity of the surface of the bicomponent superhydrophilic fiber is 60%.

[0074] Tests showed that the bicomponent superhydrophilic fiber prepared in Example 1 had a tensile strength of 4.8 cN / dtex and an elastic modulus of 10 GPa.

[0075] Figure 3 The image shows the hydrophilic effect of the bicomponent superhydrophilic fiber prepared in Example 1.

[0076] Example 2

[0077] The difference between Example 2 and Example 1 is that in step S2, the content of nano-SiO2 particles in the SiO2 / water-soluble PET composite masterbatch is 7wt%, while the rest is the same as in Example 1, and will not be repeated here.

[0078] SEM image of the bicomponent superhydrophilic fiber prepared in Example 2 is shown below. Figure 4 As shown.

[0079] As can be seen, the surface of the bicomponent superhydrophilic fiber has a small number of pores with a diameter of 1.2-2.5 μm and protrusions with a height of 10-50 nm. The pore depth is 1-3 μm, and the open porosity of the surface of the bicomponent superhydrophilic fiber is 30%.

[0080] The bicomponent superhydrophilic fiber prepared in Example 2 has a breaking strength of 5.0 cN / dtex and an elastic modulus of 12 GPa.

[0081] Comparative Example 1

[0082] The difference between Comparative Example 1 and Example 1 is that in step S4, the SiO2 / PET fibers are treated at 85°C for 2 hours, at 90°C for 1 hour, and at 95°C for 4 hours, with a heating rate of 5°C / hour. The rest is the same as in Example 1 and will not be repeated here.

[0083] Figure 5 This is a diagram illustrating the hydrophilic effect of the core-sheath structured bicomponent superhydrophilic fiber prepared in Comparative Example 1.

[0084] Comparative Example 2

[0085] The difference between Comparative Example 2 and Example 1 is that step S4 was not performed. Everything else is the same as in Example 1, and will not be repeated here.

[0086] Experiments show that the composite fiber prepared in Comparative Example 2 has a smooth, non-porous surface and a specific surface area of ​​29 m². 2 / g, tensile strength at break is 5.2cN / dtex, and elastic modulus is 12 GPa.

[0087] Comparative Example 3

[0088] The difference between Comparative Example 3 and Example 1 is that in step S4, SiO2 / PET fibers were directly soaked in 80°C hot water for 6 hours. The rest is the same as in Example 1 and will not be repeated here.

[0089] Comparative Example 4

[0090] The difference between Comparative Example 4 and Example 1 is that in step S4, SiO2 / PET fibers were directly soaked in 95°C hot water for 6 hours. The rest is the same as in Example 1 and will not be repeated here.

[0091] Comparative Example 5

[0092] The difference between Comparative Example 5 and Example 1 is that in step S4, a gradient cooling process is used, specifically a three-stage gradient temperature control process of 95℃→90℃→80℃. The SiO2 / PET fiber is treated at 95℃ for 3 h, at 90℃ for 1 h, and at 80℃ for 2 h, with a heating rate of 5℃ / h. The rest is the same as in Example 1, and will not be repeated here.

[0093] The hydrophilicity of the composite fibers prepared in Examples 1-2 and Comparative Examples 1-5 was tested according to the FZ / T 50040-2018 Test Method for Hydrophilicity of Short Chemical Fibers. The test results are shown in Table 1.

[0094] Table 1. Performance summary of Examples 1-2 and Comparative Examples 1-5

[0095]

[0096] Comparing Example 1 with Comparative Example 1, it can be seen that when the temperature treatment time in the third stage is too long, the pores become too deep, causing the silica to fall off and form large pores without protrusions, reducing the roughness and thus decreasing the hydrophilicity.

[0097] Comparing Example 1 and Comparative Example 2, it can be seen that without the three-stage heating treatment, the fiber skin surface has no porous structure, and the silica encapsulated by hydrophilic PET cannot be exposed. Only a small amount of silica particles on the outer layer play a role in improving the roughness.

[0098] Comparing Example 1 and Comparative Example 3, it can be seen that when only a relatively low temperature is used for treatment, a small number of pores are formed on the surface of the fiber skin. The pore size is small, the nanoscale protrusions are low, the roughness is low, and the hydrophilicity is reduced.

[0099] Comparing Example 1 and Comparative Example 4, it can be seen that when only a relatively high temperature is used for treatment, the long-term high-temperature treatment causes the hydrophilic PET itself to begin to dissolve, in addition to the weak interface where silica and hydrophilic PET come into contact. As a result, a large number of macropores are formed, making it impossible to form nano-sized protrusions and reducing hydrophilicity.

[0100] Comparing Example 1 with Comparative Example 5, it can be seen that if the initial temperature is too high, in addition to the weak interface where silica and hydrophilic PET come into contact, the hydrophilic PET itself also begins to dissolve, forming a small number of small pores. Once pores appear, under continuous high-temperature treatment, the pores will continue to grow larger, eventually forming a large number of large pores, making it impossible to form nano-sized protrusions, and reducing hydrophilicity.

[0101] According to AATCC 61-2013e(2020) Colorfastness to Laundering: Accelerated standard, the composite fibers prepared in Examples 1-2 and Comparative Examples 1-5 were subjected to 50 standard washes. The fiber surface was imaged using a scanning electron microscope (SEM) under the same magnification and sampling conditions, and the number density of silica particles per unit area (particles / μm²) was statistically analyzed using the image, denoted as n0. After washing, n was obtained using the same method. 50 The durability of the coating is characterized by the particle retention rate R, calculated as R = (n 50 / n0)×100%. The hydrophilicity of the sample after washing was also tested, expressed as wicking height. The data are shown in Table 2.

[0102] Table 2. SiO2 particle retention and hydrophilicity of fibers after 50 standard washes

[0103]

[0104] As shown in the table above, the bicomponent superhydrophilic fiber with a core-sheath structure prepared in this application has good wash resistance. After 50 standard washes, the SiO2 particle retention rate reaches 95-98%.

[0105] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A method for preparing a core-sheath structured bicomponent superhydrophilic fiber, characterized in that, Includes the following steps: S1. Terephthalic acid, isophthalic acid, ethylene glycol, and neopentyl glycol are placed in a reaction vessel in a preset ratio, nitrogen gas is introduced, and pressure is applied to carry out an esterification reaction. After the esterification reaction is completed, sodium bis(hydroxyethyl) isophthalate-5-sulfonate is added to polyethylene glycol to carry out a polycondensation reaction. After the reaction is completed, a water-soluble polyester material is obtained, which is then granulated to obtain a water-soluble PET masterbatch. S2, the nano-SiO2 particles are uniformly mixed with the water-soluble PET masterbatch obtained in step S1, and then melt-extruded and granulated to obtain a SiO2 / water-soluble PET composite masterbatch; the content of nano-SiO2 particles in the SiO2 / water-soluble PET composite masterbatch is 14 wt%. S3, PET masterbatch and SiO2 / water-soluble PET composite masterbatch obtained in step S2 are added to the core layer and sheath layer feed inlets respectively, and SiO2 / PET fiber with sheath core structure is prepared by a two-component melt spinning machine; S4. The SiO2 / PET fiber with a core-sheath structure prepared in step S3 is immersed in hot water at 85°C and treated with a three-stage gradient temperature control process of 85°C→90°C→95°C for 6 hours to dissolve the water-soluble PET in the sheath layer and obtain a bicomponent superhydrophilic fiber. The three-stage gradient temperature control process specifically involves treating the SiO2 / PET fiber at 85°C for 2 hours, at 90°C for 2 hours, and at 95°C for 2 hours, with a heating rate of 5°C / h.

2. The method for preparing the core-sheath structured bicomponent superhydrophilic fiber according to claim 1, characterized in that, In step S3, the flow rate ratio of the SiO2 / water-soluble PET composite masterbatch to the PET masterbatch is 1:(1.5-4).

3. The method for preparing the core-sheath structured bicomponent superhydrophilic fiber according to claim 1, characterized in that, The degree of sulfonation of water-soluble PET is 10-15 mol.

4. The method for preparing the core-sheath structured bicomponent superhydrophilic fiber according to claim 1, characterized in that, The particle size of the nano-SiO2 particles is 10-35 nm.

5. The method for preparing the core-sheath structured bicomponent superhydrophilic fiber according to claim 1, characterized in that, In step S3, the intrinsic viscosity of the PET masterbatch is 0.68-0.75 dL / g.

6. A core-sheath structured bicomponent superhydrophilic fiber, characterized in that, The bicomponent superhydrophilic fiber is prepared by any one of the preparation methods described in claims 1-5.

7. The bicomponent superhydrophilic fiber with a core-sheath structure according to claim 6, characterized in that, The surface of the bicomponent superhydrophilic fiber has several pores with a diameter of 80-250 nm, protrusions with a height of 10-50 nm, and a pore depth of 1-3 μm; the open porosity of the surface of the bicomponent superhydrophilic fiber is 30-65%.

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