Preparation method of elastic hollow fiber with inner spiral channel

Abstract

The present invention provides a method for preparing an elastic hollow fiber with an internal spiral channel, wherein the spinning liquid is used as the external phase and the coagulant solution is used as the internal phase, a coaxial spinneret is used for spinning, and the flow rate of the internal and external phases is controlled, and finally the obtained fiber is immersed in a coagulation bath with the same composition as the coagulant solution to shape the hollow structure and internal spiral structure inside the fiber, and then dried to obtain an elastic hollow fiber with a yarn shape and a spiral channel inside. The elastic hollow fiber prepared by the above method can utilize the double diffusion phenomenon of the contact surface of the internal and external phases when the internal and external phases flow out of the capillary to cause the fiber to curl and form an internal spiral structure therein. The continuity of the fiber is good during the preparation process, and the internal spiral distribution of the obtained fiber is uniform and elastic, which broadens the application of hollow fibers in the field of smart wearables.

Description

Technical Field

[0001] The invention relates to the technical field of elastic hollow fibers, and in particular to a method for preparing an elastic hollow fiber with an inner spiral channel. Background Art

[0002] Due to its unique three-dimensional geometric structure, the helical structure has the characteristics of high deformation, high recovery rate and high flexibility. It has shown potential application prospects in tissue engineering, microswimmers, drug delivery, pollutant adsorption, flexible smart wearables and other fields.

[0003] In the prior art, the patent document with application number CN202111134964.1 and publication date of January 11, 2022, entitled “A method for constructing high-strength spiral fibers by microfluidic spinning” adopts a microfluidic spinning method to spin a polymer solution, with the polymer solution as the inner phase and the coagulation bath as the outer phase, so as to utilize the solvent exchange between the polymer solution and the coagulation bath, thereby increasing the viscosity of the polymer solution and causing phase separation to occur, thereby obtaining spiral fibers. The spiral fibers prepared by the above method exhibit high strength characteristics, but the above fibers are difficult to maintain their spiral structure during actual application, especially after they are processed and prepared into products, which causes the spiral structure of the fiber to be damaged, affecting the performance of the fiber spiral properties.

[0004] In view of this, it is necessary to design an improved method for preparing elastic hollow fibers with inner spiral channels to solve the above problems. Summary of the Invention

[0005] The object of the present invention is to provide a method for preparing an elastic hollow fiber with an inner spiral channel.

[0006] To achieve the above-mentioned object of the invention, the present invention provides a method for preparing an elastic hollow fiber having an inner spiral channel, comprising the following steps:

[0007] S1. dissolving the polymer in a solvent to prepare a uniform, bubble-free spinning solution;

[0008] S2. Using the spinning solution in step S1 as the outer phase and the coagulant solution as the inner phase, a homemade coaxial spinneret is used for coaxial wet spinning or dry spinning. The outer side of the inner needle of the coaxial spinning head is connected to a capillary. The entire fiber section is immersed in a coagulation bath and dried to obtain the elastic hollow fiber with an inner diameter of 50-900 μm.

[0009] Preferably, in step S2, the coagulant solution and the coagulation bath have the same composition, and the coagulation bath is one or more of deionized water, ethanol, N,N-dimethylformamide, dimethyl sulfoxide, and sodium sulfate.

[0010] Preferably, in step S2, the flow rate ratio of the outer phase to the inner phase is 1-10.

[0011] Preferably, in step S2, the length of the connecting tube of the coaxial spinneret is more than 1.5 times the length of the inner needle, the inner diameter of the connecting tube is greater than 0.1 mm different from the outer diameter of the inner needle, and the inner diameter of the inner needle is 0.06-2.00 mm.

[0012] Preferably, in step S1, the polymer is one of polyurethane, SBS, polyvinyl chloride, and polyvinyl alcohol.

[0013] Preferably, in step S1, the concentration of the spinning solution is 5-50%.

[0014] Preferably, in step S1, the solvent is one of deionized water, N,N-dimethylformamide, tetrahydrofuran, cyclohexanone, dimethyl sulfoxide or ethanol.

[0015] The beneficial effects of the present invention are:

[0016] The present invention proposes a method for preparing an elastic hollow fiber with an internal spiral channel. The method comprises the following steps: using a spinning solution as the outer phase and a coagulant solution as the inner phase, adopting a coaxial spinneret for spinning, and controlling the flow rates of the inner and outer phases. Finally, the prepared fiber is immersed in a coagulation bath having the same composition as the coagulant solution to shape the hollow structure and the internal spiral structure of the fiber. After drying, an elastic hollow fiber with a yarn appearance and an internal spiral channel is obtained. The elastic hollow fiber prepared by the above method can utilize the differences in the composition of the internal and external phases, flow rates and the dimensional characteristics of the connecting tubes in the coaxial spinneret. When the internal and external phases flow out of the coaxial spinneret, a stable laminar flow phenomenon is formed in the capillary. When flowing out of the capillary, a double diffusion phenomenon occurs at the contact surface of the internal and external phases, which increases the viscosity of the interface, causing it to bend and become unstable, curling and forming an internal spiral structure inside the fiber. The fiber has good continuity during the preparation process, and the internal spiral distribution of the prepared fiber is uniform and elastic. Secondly, the method proposed in the present invention does not require a complex control process, and has the advantages of simple operation and high production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a SEM image of the elastic hollow fiber with an inner spiral channel prepared in Example 1 of the present invention;

[0018] Figure 2 This is an optical photograph of the elastic hollow fiber prepared in Example 1 when filled with a fluorescent agent;

[0019] Figure 3 for Figure 1SEM image of the internal structure of the elastic hollow fiber with inner spiral channels;

[0020] Figure 4 Schematic diagram of the structure of the coaxial spinning head to which the present invention is applied;

[0021] The reference numerals are as follows:

[0022] 1. Connecting tube; 2. Inner needle; 3. Capillary tube. DETAILED DESCRIPTION

[0023] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] It should also be noted here that, in order to avoid obscuring the present invention due to unnecessary details, only structures and / or processing steps closely related to the solutions of the present invention are shown in the drawings, while other details that are not closely related to the present invention are omitted.

[0025] In addition, it should be noted that the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.

[0026] See also Figure 1 As shown, the present invention provides a method for preparing an elastic hollow fiber with an inner spiral channel, comprising the following steps:

[0027] S1. dissolving the polymer in a solvent to prepare a uniform, bubble-free spinning solution;

[0028] S2. Using the spinning solution in step S1 as the outer phase and the coagulant solution as the inner phase, a homemade coaxial spinneret is used for coaxial spinning or dry spinning. The outer side of the inner needle 2 of the coaxial spinning head is connected to a capillary 3, which is used as an outer needle. After the fiber is formed, the entire fiber is immersed in a coagulation bath and dried to obtain an elastic hollow fiber with an inner diameter of 50-900 μm. During the fiber preparation process, the spinning solution is injected into the connecting tube 1 of the coaxial spinning head, and the coagulant solution is injected into the inner needle 2 of the coaxial spinning head. It should be noted that the capillary 3 here is used to provide auxiliary effect for the formation of the fiber so that the fiber can be better formed. Therefore, the capillary 3 does not need to be consistent with the length of the fiber to be prepared, and its length can be set as needed.

[0029] Preferably, in step S1, the polymer is one of polyurethane, SBS (styrene-butadiene-styrene block copolymer), polyvinyl chloride, and polyvinyl alcohol.

[0030] Preferably, in step S1, the solvent is one of deionized water, N,N-dimethylformamide, tetrahydrofuran, cyclohexanone, dimethyl sulfoxide or ethanol.

[0031] Preferably, in step S1, the concentration of the spinning solution is 5-50%.

[0032] Preferably, in step S2, the coagulant solution and the coagulation bath have the same composition, and are one or more of deionized water, ethanol, N,N-dimethylformamide, dimethyl sulfoxide, and sodium sulfate.

[0033] Preferably, in step S2, the flow rate ratio of the outer phase to the inner phase is 1-10. When the flow rates of the inner and outer phases are within this range, it can be ensured that the internal structure of the formed fiber is uniform and the fiber is intact.

[0034] Preferably, in step S2, the length of the connecting tube 1 of the coaxial spinneret is more than 1.5 times the length of the inner needle 2, the difference between the inner diameter of the connecting tube 1 and the outer diameter of the inner needle 2 is greater than 0.1 mm, and the inner diameter of the inner needle 2 is 0.06-2.00 mm; preferably, the length of the connecting tube 1 of the coaxial spinneret is 1.5-3 times the length of the inner needle 2.

[0035] Preferably, in step S2, the soaking time is 1-24 hours.

[0036] Preferably, in step S2, the drying temperature is 25-30°C and the drying time is more than 12 hours.

[0037] The preparation method of the elastic hollow fiber with an inner spiral channel of the present invention is further described below with reference to specific embodiments:

[0038] Example 1

[0039] The present invention prepares an elastic hollow fiber with an inner spiral channel. The specific preparation method includes the following steps:

[0040] S1, dissolving polyurethane in DMF to prepare a spinning solution with a concentration of 20%;

[0041] S2. Using the spinning solution in step S1 as the outer phase and deionized water as the inner phase, coaxial spinning is performed using a homemade coaxial spinning head at a flow rate ratio of 2 between the outer phase and the inner phase. A capillary 3 is set at the end of the coaxial spinning head. After the fiber is formed, the entire fiber is immersed in deionized water for 120 minutes and then dried at 25°C for 24 hours to obtain an elastic hollow fiber with an inner diameter of 150.16 μm and a spacing between the spirals inside the fiber of 693.45 μm.

[0042] The SEM images of the elastic hollow fiber prepared in this embodiment and the SEM images of the internal structure of the fiber are shown in FIG. Figure 1 and Figure 3 As shown in the figure, it can be seen that a uniformly distributed inner spiral structure is formed inside the fiber. In order to observe the inner spiral structure inside the fiber more clearly, a fluorescent agent is filled inside the fiber. The optical photo is shown in Figure 2 As shown in the figure, the inner spiral structure inside the fiber can be clearly observed. The results show that this example successfully prepared a hollow fiber with an inner spiral structure.

[0043] Examples 2 to 3

[0044] The only difference between Examples 2 and 3 and Example 1 is that the flow rate ratio of the external phase to the internal phase during the spinning process is different from that in Example 1. The other steps are essentially the same as in Example 1 and are not further described here. The flow rate ratios of the external phase to the internal phase during the spinning process in Examples 1 to 3 and the properties of the hollow fibers produced under these conditions are shown in Table 1. This table shows that the flow rate ratio of the internal phase to the internal phase affects properties such as the fiber's inner diameter, helical pitch, and elongation.

[0045] Table 1 Flow rate ratio of the external phase to the internal phase in the spinning process in Examples 1 to 3 and properties of the hollow fibers obtained under the corresponding conditions

[0046] project Flow rate ratio Fiber inner diameter (μm) Helical pitch (μm) Elongation (%) Example 1 2 150.16 693.45 903 Example 2 3 132.68 442.12 874 Example 3 4 118.67 248.26 1006

[0047] Comparative Example 1

[0048] The only difference between Comparative Example 1 and Example 1 is that in step S2, the spinning solution is used as the inner phase and the coagulation bath solution is used as the outer phase. The other steps are basically the same as those in Example 1 and will not be described in detail here. Figure 4 As shown in the figure, the fiber is spiral in shape, and there is no internal spiral structure inside the fiber. This is because: in Comparative Example 1, the spinning solution is used as the internal phase solution, and the mass transfer effect only occurs externally to form a solid-phase fiber, while in Example 1, the spinning solution is used as the external phase and the coagulation bath solution is used as the internal phase. The mass transfer effect occurs both inside and outside the spinning solution, and the solid phase is formed into a hollow fiber.

[0049] The preparation mechanism of the elastic hollow fiber with an internal spiral channel of the present invention is explained below: by using the spinning solution as the outer phase and the coagulant solution as the inner phase, a coaxial spinneret is used for spinning, and the flow rate of the inner and outer phases is controlled. The spinning process can utilize the differences in the composition, flow rate and dimensional characteristics of the inner and outer phases and the connecting tube 1 in the coaxial spinneret. When the inner and outer phases flow out of the coaxial spinneret, a stable laminar flow phenomenon is formed in the capillary 3. When flowing out of the capillary 3, the force exerted on the inner phase is greater than that on the outer phase, so that the inner and outer phases produce different coiling forms, forming an internal spiral structure inside the fiber, and forming a hollow structure inside the fiber as the coagulant solution evaporates during the drying process; then, it is immersed in a coagulation bath with the same composition as the coagulation bath solution, and the fiber is shaped by the coagulation bath solution inside and outside the fiber and the squeezing effect of the coagulation bath on the fiber, so that the internal spiral structure inside the fiber remains stable.

[0050] In summary, the method for preparing an elastic hollow fiber with an internal spiral channel proposed by the present invention is to use a spinning solution as the outer phase and a coagulation bath solution as the inner phase, and to use a coaxial spinneret for spinning. The flow rates of the inner and outer phases are controlled, and finally the obtained fiber is immersed in a coagulation bath having the same composition as the coagulation bath solution to shape the hollow structure and internal spiral structure inside the fiber. After drying, an elastic hollow fiber with a yarn shape and an internal spiral channel is obtained. The elastic hollow fiber obtained by the above method can utilize the double diffusion phenomenon at the contact surface of the inner and outer phases when the inner and outer phases flow out of the capillary to cause the fiber to curl and form an internal spiral structure therein. During the drying process, a hollow structure is formed inside the fiber as the coagulant solution evaporates. The fiber has good continuity during the preparation process, and the internal spiral distribution of the obtained fiber is uniform and elastic.

[0051] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing an elastic hollow fiber having an inner spiral channel, characterized in that: The steps include: S1. dissolving the polymer in a solvent to prepare a uniform, bubble-free spinning solution; S2. Using the spinning solution in step S1 as the outer phase and the coagulant solution as the inner phase, a homemade coaxial spinneret is used for coaxial wet spinning or dry spinning. The outer side of the inner needle of the coaxial spinneret is connected to a capillary. The entire fiber section is immersed in a coagulation bath and dried to obtain the elastic hollow fiber with an inner diameter of 50-900 μm; the length of the connecting tube of the coaxial spinneret is more than 1.5 times the length of the inner needle, the difference between the inner diameter of the connecting tube and the outer diameter of the inner needle is greater than 0.1 mm, and the inner diameter of the inner needle is 0.06-2.00 mm; the capillary is used as the outer needle, the port of the inner needle is located inside the capillary, and the port of the inner needle is not flush with the port of the capillary.

2. The method for preparing an elastic hollow fiber having an inner spiral channel according to claim 1, characterized in that: In step S2, the coagulant solution and the coagulation bath have the same composition, and the coagulation bath is one or more of deionized water, ethanol, N,N-dimethylformamide, dimethyl sulfoxide, and sodium sulfate.

3. The method for preparing an elastic hollow fiber having an inner spiral channel according to claim 1, characterized in that: In step S2, the flow rate ratio of the outer phase to the inner phase is 1-10.

4. The method for preparing an elastic hollow fiber having an inner spiral channel according to claim 1, characterized in that: In step S1, the polymer is one of polyurethane, SBS, polyvinyl chloride, and polyvinyl alcohol.

5. The method for preparing an elastic hollow fiber having an inner spiral channel according to claim 1, characterized in that: In step S1, the concentration of the spinning solution is 5-50%.

6. The method for preparing an elastic hollow fiber having an inner spiral channel according to claim 1, characterized in that: In step S1, the solvent is one of deionized water, N,N-dimethylformamide, tetrahydrofuran, cyclohexanone, dimethyl sulfoxide or ethanol.

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