Preparation method of short fiber and bacterial cellulose-calcium alginate aerogel fiber composite yarn

Abstract

The invention discloses a preparation method of short fiber and bacterial cellulose-calcium alginate aerogel fiber composite yarn. The preparation method comprises the following steps: (1) preparing a spinning solution from bacterial cellulose and sodium alginate; (2) extruding the spinning solution into a coagulating bath by adopting an injection pump to obtain hydrogel fibers, transferring the hydrogel fibers into replacement liquid to replace moisture in the hydrogel fibers, and then freezing and drying to obtain bacterial cellulose-calcium alginate aerogel fibers; and (3) blending the short fibers and the bacterial cellulose-calcium alginate aerogel fibers by adopting a friction spinning process to obtain the short fiber and bacterial cellulose-calcium alginate aerogel fiber composite yarn. The aerogel fibers prepared from the bacterial fibers and the sodium alginate have high mechanical properties and torsion resistance, and the composite yarn with the bacterial cellulose-calcium alginate aerogel fibers coated with the short fibers is prepared through the friction spinning technology, so that the aerogel fibers have spinnability.

Description

Technical Field

[0001] The present invention relates to the technical field of textiles, and particularly relates to a method for preparing a composite yarn of short fibers and bacterial cellulose-calcium alginate aerogel fibers. Background Art

[0002] Aerogel fibers have characteristics such as a three-dimensional network porous structure, low density, high porosity, and low thermal conductivity. They can be used in fireproof clothing, spacesuits, and daily warm clothing, etc., and have broad application prospects in the fields of heat insulation and aerospace. They are known as a new generation of heat insulation materials.

[0003] Currently, aerogel fibers mainly include silica aerogel fibers, polyimide aerogel fibers, and cellulose aerogel fibers, etc. Among them, silica aerogel fibers have poor mechanical properties and a powder falling phenomenon, and their spinnability is poor; polyimide aerogel has good mechanical properties, but the preparation process is complex, time-consuming, involves a variety of organic solvents, is not environmentally friendly, and has a low torsional stiffness, making it difficult to carry out textile processing; the preparation of cellulose aerogel fibers usually dissolves cellulose in organic solvents such as DMSO, NMP, or DMAC to prepare a spinning dope, and then extrudes it into a coagulation bath to prepare aerogel fibers, but the obtained aerogel fibers have poor mechanical properties. Therefore, the preparation of aerogel fibers with both high strength and torsional properties is still a bottleneck in current technology, and due to the difficult-to-twist nature of aerogel fibers, it is more difficult to spin aerogel fibers into yarns. Summary of the Invention

[0004] To solve the above technical problems, the present invention provides a method for preparing a composite yarn of short fibers and bacterial cellulose-calcium alginate aerogel fibers.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A method for preparing a composite yarn of short fibers and bacterial cellulose-calcium alginate aerogel fibers, comprising the steps of:

[0007] (1) Prepare a bacterial cellulose suspension, add sodium alginate powder, and stir well to dissolve sodium alginate and mix bacterial cellulose and sodium alginate evenly to prepare a spinning dope;

[0008] (2) Use an injection pump to extrude the spinning dope into a coagulation bath to obtain formed hydrogel fibers, transfer the hydrogel fibers to a displacement liquid to displace the moisture in the hydrogel fibers, and then perform freezing and drying to obtain bacterial cellulose-calcium alginate aerogel fibers;

[0009] (3) Use a friction spinning process to blend short fibers with bacterial cellulose-calcium alginate aerogel fibers to obtain a composite yarn of short fibers and bacterial cellulose-calcium alginate aerogel fibers.

[0010] Further, in the step (1), the mass concentration of the bacterial cellulose suspension is 0.5-5.0%, and the mass ratio of the solid content of the bacterial cellulose to the sodium alginate is 0.2-5:1.

[0011] Further, in the step (2), the solution used in the coagulation bath is a calcium chloride solution, and the displacement liquid is an aqueous solution of ethanol, tert-butanol or propanol.

[0012] Further, the mass concentration of the calcium chloride solution is 1-10%, and the volume concentration of the aqueous solution of ethanol, tert-butanol or propanol is 5-50%.

[0013] Further, in the step (2), the injection speed of the injection pump is 50-300 mL / h.

[0014] Further, in the step (2), the freezing method is liquid nitrogen freezing or refrigerator freezing, and the freezing temperature is -196°C to -20°C.

[0015] Further, in the step (3), the composite yarn prepared by friction spinning is a core-spun yarn with short fibers covering the bacterial cellulose-calcium alginate aerogel fiber.

[0016] Further, in the step (3), the short fibers used in the friction spinning are at least one of cotton fiber, viscose fiber, polyester fiber, polyamide fiber and aramid fiber.

[0017] The beneficial effects of the present invention are as follows:

[0018] (1) The present invention provides a preparation method of a composite yarn of short fibers and bacterial cellulose-calcium alginate aerogel fibers. A spinning dope is prepared by mixing bacterial cellulose and sodium alginate, and is solidified and formed by calcium ions. Bacterial cellulose can provide a continuous and non-agglomerated cellulose spatial network at a certain concentration. The bacterial cellulose spatial network ensures the stable spatial structure and excellent torsional resistance of the aerogel fiber. The sodium alginate solution is evenly dispersed on the surface of the bacterial cellulose nanofibers, and after being solidified by calcium chloride, it further ensures the structural stability of the aerogel fiber, improves the mechanical properties and torsional resistance of the aerogel fiber, enables it to withstand a certain amount of torsion during the spinning process, and realizes the preparation of the aerogel fiber composite yarn;

[0019] (2) The present invention provides a method for preparing a composite yarn of short fibers and bacterial cellulose-calcium alginate aerogel fibers. The short fibers and the bacterial cellulose-calcium alginate aerogel fibers are blended by friction spinning process. The unique spinning characteristics of friction spinning enable the aerogel fibers to be subjected to only limited torsion during the spinning process. Using this spinning process, a composite yarn with short fibers coating the bacterial cellulose-calcium alginate aerogel fibers can be prepared, greatly improving the mechanical properties of the aerogel fibers and endowing the aerogel fibers with spinnability, which can be used to prepare textile products;

[0020] (3) The present invention provides a method for preparing a composite yarn of short fibers and bacterial cellulose-calcium alginate aerogel fibers. Using bacterial cellulose and sodium alginate as raw materials, it has the characteristics of wide source, biodegradability, renewability, environmental friendliness, etc. In addition, sodium alginate also has flame retardancy, which also makes the prepared aerogel fibers have certain flame retardancy. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0022] Figure 1 It is a schematic diagram of the cross-linking effect of bacterial cellulose, sodium alginate and calcium ions of the present invention;

[0023] Figure 2 It is a scanning electron microscope photograph of the aerogel fibers prepared in Example 1 of the present invention;

[0024] Figure 3 It is a scanning electron microscope photograph of the composite yarn prepared in Example 1 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] The present invention provides a method for preparing a composite yarn of short fibers and bacterial cellulose-calcium alginate aerogel fibers. To make the purpose, technical solutions and effects of the present invention clearer and more definite, the following further details the present invention. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0026] The present invention provides a method for preparing a composite yarn of short fibers and bacterial cellulose-calcium alginate aerogel fibers, including the steps of:

[0027] (1) Prepare a bacterial cellulose suspension, add sodium alginate powder, and stir well to dissolve the sodium alginate and mix the bacterial cellulose and sodium alginate evenly to prepare a spinning dope;

[0028] Specifically, in this step, the mass concentration of the bacterial cellulose suspension is 0.5-5.0%, and the mass ratio of the solid content of bacterial cellulose to sodium alginate is 0.2-5:1. Bacterial cellulose is preferably used as the bacterial cellulose;

[0029] (2) Use a syringe pump to extrude the spinning dope into a coagulation bath to obtain a formed hydrogel fiber. Transfer the hydrogel fiber to a displacement liquid to displace the water in the hydrogel fiber, and then perform freezing and drying to obtain a bacterial cellulose-calcium alginate aerogel fiber;

[0030] Specifically, in this step, the solution used in the coagulation bath is a calcium chloride solution, and the mass concentration of the calcium chloride solution is 1-10%; the displacement liquid is an aqueous solution of ethanol, tert-butanol or propanol, and the volume concentration of the ethanol, tert-butanol or propanol aqueous solution is 5-50%; the injection speed of the syringe pump is 50-300 mL / h; the freezing method is liquid nitrogen freezing or refrigerator freezing, and the freezing temperature is -196°C to -20°C;

[0031] (3) Use a friction spinning process to blend short fibers with the bacterial cellulose-calcium alginate aerogel fiber to obtain a composite yarn of short fibers and bacterial cellulose-calcium alginate aerogel fiber;

[0032] Specifically, in this step, the short fibers used in the friction spinning are at least one of cotton fiber, viscose fiber, polyester fiber, polyamide fiber, and aramid fiber, and their length is 35-150 mm; and the composite yarn prepared by friction spinning is a core-spun yarn with short fibers covering the bacterial cellulose-calcium alginate aerogel fiber.

[0033] Through the above technical solutions, the present invention solves the problem that aerogel fibers cannot be processed by textile due to poor mechanical properties and low torsional stiffness. Specifically, the present invention mainly solves this problem through the following aspects:

[0034] In the first aspect, the present invention utilizes the structural characteristics of bacterial cellulose, which has a nano-scale spatial network structure. By controlling its concentration, it is uniformly dispersed in an aqueous solution to form a continuous and non-aggregated cellulose spatial network. The bacterial cellulose spatial network ensures the stable spatial structure and excellent torsional resistance of the aerogel fiber;

[0035] In a second aspect, the present invention uniformly mixes bacterial cellulose and sodium alginate and then spins them. The resulting hydrogel fibers are solidified and formed by a calcium chloride solution, and then aerogel fibers are obtained by freeze-drying. During the formation of the gel fibers, the bacterial cellulose in the spinning dope serves as the "skeleton" of the aerogel fibers, while the sodium alginate solution is uniformly dispersed on the surface of the bacterial cellulose nanofibers. After being solidified by calcium chloride into calcium alginate, it becomes the "cement" of the aerogel fibers, making it a structure similar to "reinforced concrete". This not only ensures the structural stability of the aerogel fibers but also improves the mechanical properties of the aerogel fibers through the connection of "reinforced concrete". Additionally, referring to Figure 1 , after injecting the spinning solution of bacterial cellulose and sodium alginate into the calcium chloride solution, since there are hydroxyl groups on bacterial cellulose and hydroxyl and carboxyl groups on sodium alginate, hydrogen bonds will form between the hydroxyl and carboxyl groups. At the same time, hydrogen bonds will also form between and within cellulose molecules. Through hydrogen bond action and calcium ion cross-linking, hydrogel fibers are solidified and formed.

[0036] In a third aspect, in order to ensure the structural stability of bacterial cellulose and calcium alginate hydrogel fibers during freeze-drying, after preparing the bacterial cellulose and calcium alginate hydrogel fibers, a displacement liquid with a low surface energy, such as tert-butanol, is first used to displace the water in the bacterial cellulose and calcium alginate hydrogel fibers. After the displacement is completed, freeze-drying is then carried out.

[0037] Furthermore, in the present invention, the above three aspects are combined with each other and work together. If ordinary cellulose is used instead of bacterial cellulose, or the concentration of bacterial cellulose is too low or too high, it is difficult to form an interconnected and continuous bacterial cellulose network. Even if cellulose-calcium alginate aerogel fibers are prepared by adding sodium alginate, due to the discontinuous spatial structure of cellulose, its torsional resistance cannot be guaranteed. If only bacterial cellulose is used without adding sodium alginate, calcium alginate cannot be coated on the bacterial cellulose, that is, the "reinforced concrete" structure cannot be formed, resulting in poor structural stability and mechanical properties of the aerogel fibers, and even the aerogel fibers cannot be formed. If the hydrogel fibers are directly freeze-dried, due to the high surface energy of water, it will damage the combination of bacterial cellulose and calcium alginate during the sublimation of freeze-drying, thereby destroying the structure of the aerogel fibers, which may lead to a decrease in both the porosity and torsional resistance. The present invention realizes the structural stability, high mechanical properties, and torsional resistance of the aerogel fibers through the combination of the above three aspects.

[0038] On the basis of solving the problems of poor mechanical properties and low torsional stiffness of aerogel fibers through the above three aspects, the present invention also spins the aerogel fibers. Conventional spinning methods require twisting the fibers. The fibers need to be twisted multiple times and are intertwined with other fibers, which requires relatively high resistance to bending, compression, and torsion of the fibers. Even though the aerogel fibers prepared by the method of the present invention have relatively good torsional resistance, in practice, the inherent properties of the aerogel fibers that are not easily compressible and twisted cannot be avoided. Therefore, the present invention uses friction spinning to mix and spin the above-mentioned aerogel fibers and other short fibers, with the aerogel fibers as the core yarn and other short fibers coated on the aerogel fibers. Due to the unique spinning characteristics of friction spinning, the aerogel fibers only undergo limited torsion during the spinning process, and the torsional resistance of the aerogel fibers prepared by the present invention can withstand this torsion. Through the aerogel fibers prepared by the present invention, supplemented by the friction spinning process, the preparation of aerogel fiber composite yarns can be realized.

[0039] It should be noted that the mechanical properties of the above-mentioned aerogel fibers mainly refer to the tensile strength.

[0040] In addition, the present invention does not have any special restrictions on the sources of all raw materials, and they can be commercially available.

[0041] Example 1

[0042] This example provides a composite yarn of short fibers and bacterial cellulose-calcium alginate aerogel fibers, and its preparation process is as follows:

[0043] (1) Prepare a 1wt% bacterial cellulose suspension, then add sodium alginate powder. The mass ratio of the solid content of sodium alginate to bacterial cellulose is 1:1. Stir well to dissolve sodium alginate and mix bacterial cellulose and sodium alginate evenly to prepare a spinning dope.

[0044] (2) Use an injection pump to extrude the spinning dope into a 3wt% calcium chloride solution at an injection speed of 80 mL / h to obtain formed hydrogel fibers. Transfer the hydrogel fibers to a 25% (volume concentration) aqueous solution of tert-butanol for replacement for 12 h, then freeze them using liquid nitrogen, that is, the freezing temperature is -196 °C, and then place them in a freeze dryer for drying to obtain bacterial cellulose-calcium alginate aerogel fibers.

[0045] (3) Use the friction spinning process to blend viscose short fibers and bacterial cellulose-calcium alginate aerogel fibers, so that the viscose short fibers coat the bacterial cellulose-calcium alginate aerogel fibers to obtain a composite yarn of short fibers and bacterial cellulose-calcium alginate aerogel fibers.

[0046] The bacterial cellulose-calcium alginate aerogel fibers prepared in step (2) of the above Example 1 were detected using a scanning electron microscope, asFigure 2 As shown, where (a) is the scanning electron microscope (SEM) photograph of the overall cross-section of the aerogel fiber, and (b) is the SEM photograph of the aerogel on the aerogel fiber. It can be seen from Figure 2 this that the aerogel fiber has a three-dimensional network porous structure.

[0047] The short fibers prepared in step (3) of the above Example 1 and the composite yarn of bacterial cellulose-calcium alginate aerogel fiber were observed. As Figure 3 shown, where (a) is the photograph of the composite yarn along its length direction, and (b) is the photograph of the cross-section of the composite yarn. It can be seen from Figure 3 this that the composite yarn is a core-sheath structure with short fibers coating the bacterial cellulose-calcium alginate aerogel fiber.

[0048] After testing, the porosity of the aerogel fiber prepared in this example is 92%, the diameter is 903 μm, the tensile strength is 2.6 N, and the single-torsion limit can reach 21 r; the porosity of the composite yarn is 80%, the diameter is about 1.6 mm, the tensile strength is 3.6 N, the single-torsion limit can reach 43 r, and the heat insulation coefficient is 0.04 W / (m·K).

[0049] Example 2

[0050] This example provides a composite yarn of short fibers and bacterial cellulose-calcium alginate aerogel fiber, and its preparation process is as follows:

[0051] (1) Prepare a 0.5 wt% bacterial cellulose suspension, then add sodium alginate powder. The mass ratio of the solid content of sodium alginate to bacterial cellulose is 1:5. Stir well to dissolve sodium alginate and mix bacterial cellulose and sodium alginate evenly to prepare a spinning dope.

[0052] (2) Use an injection pump to extrude the spinning dope into a 3 wt% calcium chloride solution at an injection speed of 200 mL / h to obtain a formed hydrogel fiber. Transfer the hydrogel fiber to an ethanol aqueous solution with a volume concentration of 10% for replacement for 12 h, then freeze it with liquid nitrogen, that is, the freezing temperature is -196 °C, and then put it into a freeze dryer for drying to obtain a bacterial cellulose-calcium alginate aerogel fiber.

[0053] (3) Use the friction spinning process to blend viscose short fibers and bacterial cellulose-calcium alginate aerogel fibers so that the viscose short fibers coat the bacterial cellulose-calcium alginate aerogel fibers to obtain a composite yarn of short fibers and bacterial cellulose-calcium alginate aerogel fibers.

[0054] After testing, the porosity of the aerogel fiber prepared in this example is 90%, the diameter of the composite yarn is about 1.6 mm, the tensile strength is 5.8 N, and the heat insulation coefficient is 0.04 W / (m·K).

[0055] Example 3

[0056] This example provides a composite yarn of short fibers and bacterial cellulose-calcium alginate aerogel fibers, and its preparation process is as follows:

[0057] (1) Prepare a 5wt% bacterial cellulose suspension, and then add sodium alginate powder. The mass ratio of the solid content of sodium alginate to bacterial cellulose is 5:1. Stir well to dissolve sodium alginate and mix bacterial cellulose and sodium alginate evenly to prepare a spinning dope;

[0058] (2) Use an injection pump to extrude the spinning dope into an 8wt% calcium chloride solution at an injection speed of 80 mL / h to obtain formed hydrogel fibers. Transfer the hydrogel fibers to an aqueous solution of tert-butanol with a volume concentration of 40% for replacement for 12 h, and then freeze them with liquid nitrogen, that is, the freezing temperature is -196°C. Subsequently, place them in a freeze dryer for drying to obtain bacterial cellulose-calcium alginate aerogel fibers;

[0059] (3) Use friction spinning technology to blend viscose short fibers with bacterial cellulose-calcium alginate aerogel fibers, so that the viscose short fibers coat the bacterial cellulose-calcium alginate aerogel fibers to obtain a composite yarn of short fibers and bacterial cellulose-calcium alginate aerogel fibers.

[0060] After testing, the porosity of the aerogel fibers prepared in this example is 85%, the diameter of the composite yarn is about 1.5 mm, the tensile strength is 12.3 N, and the heat insulation coefficient is 0.05 W / (m·K).

[0061] Comparative Example 1

[0062] The difference between this comparative example and Example 1 is that the cellulose in this comparative example is nanofibrillated cellulose (fibrous nanofibrillated cellulose) prepared by the TEMPO oxidation method, and bacterial cellulose is not used.

[0063] In the friction spinning process of this comparative example, the aerogel fibers were broken and spinning could not be carried out smoothly.

[0064] After testing, the porosity of the aerogel fibers prepared in this comparative example is 91%, the tensile strength is 0.9 N, and the single-twist limit can reach 8 r.

[0065] Comparative Example 2

[0066] The difference between this comparative example and Example 1 is that the concentration of bacterial cellulose in this comparative example is 0.03 wt%.

[0067] In the friction spinning process of this comparative example, the aerogel fibers were broken and spinning could not be carried out smoothly.

[0068] After testing, the porosity of the aerogel fiber prepared in this comparative example is 96%, the tensile strength is 0.4 N, and the single-torsion limit can reach 3 r.

[0069] Comparative Example 3

[0070] The difference between this comparative example and Example 1 is that this comparative example only uses bacterial cellulose and does not add sodium alginate.

[0071] The aerogel fiber of this comparative example cannot be formed.

[0072] Comparative Example 4

[0073] The difference between this comparative example and Example 1 is that after the formed hydrogel fiber is obtained through the coagulation bath in this comparative example, freeze-drying is directly carried out.

[0074] After testing, the porous structure of the fiber prepared in this comparative example collapses during the freeze-drying process. The porosity of the aerogel fiber prepared in this comparative example is only 66%, and the heat insulation coefficient is 0.2 W / (m·K), with poor heat insulation performance.

[0075] Comparative Example 5

[0076] The difference between this comparative example and Example 1 is that this comparative example uses the ordinary ring spinning process to blend and spin the aerogel fiber and the short fiber.

[0077] When spinning using the ring spinning process in this comparative example, the hollow structure of the aerogel fiber is damaged by twisting, the porosity is less than 10%, and a large number of fibers break during the twisting process.

[0078] It should be noted that the parts not described in this invention can be realized by adopting or referring to the existing technologies.

[0079] Of course, the above description is not a limitation to this invention, and this invention is not limited to the above examples only. The changes, modifications, additions or substitutions made by those skilled in the art within the essence of this invention should also fall within the protection scope of this invention.

Claims

1. A preparation method of a composite yarn of short fibers and bacterial cellulose-calcium alginate aerogel fibers, characterized in that, Including the steps: (1) Prepare a bacterial cellulose suspension, add sodium alginate powder, and stir well to dissolve sodium alginate and mix bacterial cellulose and sodium alginate evenly to prepare a spinning dope; (2) Use an injection pump to extrude the spinning dope into a coagulation bath to obtain a shaped hydrogel fiber, transfer the hydrogel fiber to a displacement liquid to displace the moisture in the hydrogel fiber, and then perform freezing and drying to obtain a bacterial cellulose-calcium alginate aerogel fiber; (3) Use a friction spinning process to blend short fibers with the bacterial cellulose-calcium alginate aerogel fiber to obtain a composite yarn of short fibers and bacterial cellulose-calcium alginate aerogel fibers.

2. The preparation method of a composite yarn of short fibers and bacterial cellulose-calcium alginate aerogel fibers according to claim 1, characterized in that, In the step (1), the mass concentration of the bacterial cellulose suspension is 0.5-5.0%, and the mass ratio of the solid content of bacterial cellulose to sodium alginate is 0.2-5:

1.

3. The preparation method of a composite yarn of short fibers and bacterial cellulose-calcium alginate aerogel fibers according to claim 1, characterized in that, In the step (2), the solution used in the coagulation bath is a calcium chloride solution, and the displacement liquid is an aqueous solution of ethanol, tert-butanol or propanol.

4. The preparation method of a composite yarn of short fibers and bacterial cellulose-calcium alginate aerogel fibers according to claim 4, wherein, The mass concentration of the calcium chloride solution is 1-10%, and the volume concentration of the aqueous solution of ethanol, tert-butanol or propanol is 5-50%.

5. The preparation method of a composite yarn of short fibers and bacterial cellulose-calcium alginate aerogel fibers according to claim 1, characterized in that, In the step (2), the injection speed of the injection pump is 50-300 mL / h.

6. The preparation method of a composite yarn of short fibers and bacterial cellulose-calcium alginate aerogel fibers according to claim 1, characterized in that In the step (2), the freezing method is liquid nitrogen freezing or refrigerator freezing, and the freezing temperature is -196°C to -20°C.

7. The preparation method of a composite yarn of short fibers and bacterial cellulose-calcium alginate aerogel fibers according to claim 1, characterized in that, In the step (3), the composite yarn prepared by friction spinning is a core-spun yarn with short fibers covering the bacterial cellulose-calcium alginate aerogel fiber.

8. The preparation method of a composite yarn of short fibers and bacterial cellulose-calcium alginate aerogel fibers according to claim 1, characterized in that, In the step (3), the short fibers used in friction spinning are at least one of cotton fiber, viscose fiber, polyester fiber, polyamide fiber, and aramid fiber.

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