A full-hole regenerated cellulose sponge fiber and a preparation method and application thereof

Abstract

The application belongs to the technical field of fibers, and provides full-hole regenerated cellulose sponge fibers, a preparation method and application thereof.The preparation method comprises the following steps: S1, mixing alkali, urea and water to obtain a mixed solution; S2, mixing the mixed solution with cotton linters to obtain a cellulose solution; S3, centrifuging the cellulose solution to obtain supernatant; and S4, wet spinning the supernatant to obtain full-hole regenerated cellulose sponge fibers.The application takes natural degradable biomass materials as raw materials, takes an alkali / urea system with low price as a solvent, and through the low density and high activity of hydrochloric acid, the product forms a uniform pore structure, and the formation of a dense skin layer or a gradient structure in the coagulation process is avoided.The preparation method provided by the application also has the advantages of simplicity, rapidness, low cost, mass production and the like.

Description

Technical Field

[0001] The present invention relates to the field of fiber technology, in particular to a full-pore regenerated cellulose sponge fiber and a preparation method and application thereof. Background Art

[0002] Compared to other materials, fibers are flexible and can be woven, making them widely used in clothing, thermal insulation, aerospace, biomedicine, and other fields. Biomass fibers, due to their excellent biocompatibility, are widely used in biological scaffolds, drug diagnosis, tissue culture, oral medication, and other fields.

[0003] Currently, in industrial production or experimental research, commonly used methods for preparing biomass fibers include dry spinning, wet spinning, wet extrusion, microfluidic spinning, and dry-jet wet spinning. Commonly used biomass dissolution systems include alkali / urea systems, ionic liquid systems, and LiCl / DMAc systems. Taking into account multiple factors such as technical difficulty, spinning speed, product quality, and production cost, wet spinning in an alkali / urea system is the most widely used method. In addition, microfluidic spinning also has broad application prospects for the preparation of biomass fibers in this system.

[0004] Whether wet spinning or microfluidic spinning is used, the coagulation bath plays a very important role in the production process of regenerated biomass fibers. Taking the alkali / urea solvent system as an example, commonly used coagulation baths include ethanol, dilute sulfuric acid solution, phytic acid solution, etc. However, the process of gelation of the spinning solution in the above-mentioned coagulation bath is often directional. After the outer layer of the spinning solution contacts the coagulation bath, the two react strongly first, causing the fiber surface to contact the outer layer of the coagulation bath first, resulting in the entire fiber being highly dense. Therefore, the biomass fiber produced by the traditional alkali-urea system has a skin-core structure fiber with a dense outer layer and a loose inner layer, or a densified fiber with both inner and outer layers dense; and the applicant previously constructed a type of cellulose sponge fiber with a differentiated structure (sparse outer layer and dense inner layer) based on the multi-sheath microfluidic spinning method of a microfluidic field device (patent application number: 202110341408.5). However, to date, no regenerated cellulose fiber with uniform inner and outer layers and porous structure has been reported.

[0005] Therefore, how to achieve the preparation of fully porous regenerated cellulose sponge fibers with a highly uniform porous structure and realize their unique thermal management performance applications has become an urgent problem that technicians in this field need to solve. Summary of the Invention

[0006] In view of this, the present invention provides a fully porous regenerated cellulose sponge fiber and its preparation method and application. Its purpose is to achieve the preparation of fully porous regenerated cellulose sponge fiber with highly uniform porous structure, filling the gap in this field in China.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] The present invention provides a method for preparing full-pore regenerated cellulose sponge fiber, comprising the following steps:

[0009] S1, mixing alkali, urea and water to obtain a mixed solution;

[0010] S2, mixing the mixed solution with cotton linters to obtain a cellulose solution;

[0011] S3, centrifuging the cellulose solution to obtain a supernatant;

[0012] S4. The supernatant is wet-spinned to obtain fully porous regenerated cellulose sponge fibers.

[0013] Furthermore, in step S1, the mass ratio of alkali, urea and water is 30-50:60-80:350-500.

[0014] Furthermore, in step S1, the base is sodium hydroxide or lithium hydroxide.

[0015] Furthermore, in step S2, the mass concentration of cotton linters in the cellulose solution is 3-6%; the mixing is performed by stirring for 1-5 minutes.

[0016] Furthermore, in step S3, the centrifugal speed is 5000-10000 rpm, and the centrifugal time is 20-60 min.

[0017] Furthermore, in step S4, the supernatant is first mixed with a cross-linking agent and reacted to obtain a spinning solution, and then wet spinning is performed; the cross-linking agent is epichlorohydrin.

[0018] Furthermore, the volume ratio of the supernatant to the cross-linking agent is 50-200:1-5; the reaction temperature is 0-10° C., and the reaction time is 1-3 hours.

[0019] Furthermore, in step S4, the wet spinning parameters are as follows: the pore size of the spinneret is 0.05-0.5 mm, the single hole flow rate is 200-800 μL / min, and the coagulation bath is a hydrochloric acid aqueous solution with a mass concentration of 30-70%.

[0020] The present invention provides full-pore regenerated cellulose sponge fibers prepared by the above preparation method.

[0021] The present invention also provides the use of the fully porous regenerated cellulose sponge fiber in electronic components, photothermal conversion materials, osmotic energy conversion materials, seawater desalination materials or biomedical polymer materials.

[0022] It can be seen from the above technical solution that compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] The present invention uses natural degradable biomass materials as raw materials and an inexpensive alkali / urea system as solvent. By replacing the commonly used coagulation bath of sulfuric acid with a hydrochloric acid solution through a dissolution regeneration method, the formation of a dense cortex or gradient structure during the coagulation process is avoided, and full-pore cellulose fibers with uniform pore size and distribution are prepared. The pore diameter can be adjusted by controlling the content of hydrochloric acid in the solution.

[0024] The preparation method provided by the present invention has the advantages of being simple, fast, low-cost, and mass-producible. The prepared fully porous regenerated cellulose sponge fiber has a unique structure and good biocompatibility, and can be widely used in electronic components, photothermal conversion materials, osmotic energy conversion materials, seawater desalination materials, or biomedical polymer materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a SEM image of the fully porous regenerated cellulose sponge fiber prepared in Example 1;

[0026] Figure 2 This is an SEM image of the fully porous regenerated cellulose sponge fiber prepared in Example 2;

[0027] Figure 3 This is an SEM image of the fully porous regenerated cellulose sponge fiber prepared in Example 3;

[0028] Figure 4 This is an SEM image of the fully porous regenerated cellulose sponge fiber prepared in Example 4;

[0029] Figure 5 The cross-sectional (left) and surface (right) morphologies of the gradient structure “dense outside and sparse inside” biomass fiber prepared in Comparative Example 1;

[0030] Figure 6 The cross-section (left) and enlarged cross-section (right) morphology of the gradient structure "dense outside and dense inside" biomass fiber prepared in Comparative Example 2;

[0031] Figure 7 This is the SEM image of the gradient structure "sparse outside and dense inside" fiber prepared in Comparative Example 3;

[0032] Figure 8 This is a picture of the spinneret used in the present invention. DETAILED DESCRIPTION

[0033] The present invention provides a method for preparing full-pore regenerated cellulose sponge fiber, comprising the following steps:

[0034] S1, mixing alkali, urea and water to obtain a mixed solution;

[0035] S2, mixing the mixed solution with cotton linters to obtain a cellulose solution;

[0036] S3, centrifuging the cellulose solution to obtain a supernatant;

[0037] S4. The supernatant is wet-spinned to obtain fully porous regenerated cellulose sponge fibers.

[0038] In the present invention, in step S1, the mass ratio of alkali, urea and water is 30-50:60-80:350-500, preferably 35-45:65-77:380-460, and more preferably 40:75:400.

[0039] In the present invention, in step S1, the base is sodium hydroxide or lithium hydroxide, preferably sodium hydroxide.

[0040] In the present invention, in step S2, the mass concentration of cotton linters in the cellulose solution is 3-6%, preferably 4-5%; the mixing is carried out by stirring for 1-5 minutes, preferably 2-4 minutes, and more preferably 3 minutes.

[0041] In the present invention, in step S3, the centrifugal speed is 5000-10000 rpm, preferably 6000-9000 rpm, more preferably 7000-8000 rpm; the centrifugal time is 20-60 min, preferably 30-50 min, more preferably 40 min.

[0042] In the present invention, in step S4, the supernatant is first mixed with a cross-linking agent and reacted to obtain a spinning solution, and then wet spinning is performed; the cross-linking agent is epichlorohydrin.

[0043] In the present invention, the volume ratio of the supernatant to the cross-linking agent is 50-200:1-5, preferably 100-180:2-4, and more preferably 120-150:3; the reaction temperature is 0-10°C, preferably 2-8°C, and more preferably 4-6°C; the reaction time is 1-3h, preferably 1.5-2.5h, and more preferably 2h.

[0044] In the present invention, in step S4, the parameters of wet spinning are: the aperture of the spinneret is 0.05-0.5 mm, preferably 0.1-0.4 mm, and more preferably 0.2-0.3 mm; the single hole flow rate is 200-800 μL / min, preferably 300-700 μL / min, and more preferably 400-600 μL / min; the coagulation bath is a hydrochloric acid aqueous solution with a mass concentration of 30-70%, and the mass concentration of the hydrochloric acid aqueous solution is preferably 40-60%, and more preferably 45-50%.

[0045] In the present invention, the product obtained by wet spinning in step S4 is washed with water until neutral, and then freeze-dried to obtain full-pore regenerated cellulose sponge fiber; the freeze-drying temperature is -60 to -100°C, preferably -70 to -90°C, and more preferably -80°C; the freeze-drying time is 3 to 5 hours, preferably 3.5 to 4.5 hours, and more preferably 4 hours.

[0046] The present invention provides full-pore regenerated cellulose sponge fibers prepared by the above preparation method.

[0047] The present invention also provides the use of the fully porous regenerated cellulose sponge fiber in electronic components, photothermal conversion materials, osmotic energy conversion materials, seawater desalination materials or biomedical polymer materials.

[0048] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0049] Example 1

[0050] A method for preparing fully porous regenerated cellulose sponge fiber comprises the following steps:

[0051] S1. Place 40g of sodium hydroxide and 75g of urea in a beaker, add 400g of water, and precool to obtain a mixed solution after complete dissolution;

[0052] S2, adding cotton linters to the mixture and stirring for 3 minutes to obtain a cellulose solution with a mass concentration of 3%;

[0053] S3, centrifuging the cellulose solution at 8000 rpm for 50 min to obtain a supernatant;

[0054] S4. Take 150 mL of the supernatant and mix it with 2 mL of epichlorohydrin, then react it at 4°C for 2 h to obtain a spinning solution. The spinning solution is wet-spun using a spinneret with a pore size of 0.05 mm. The supernatant is squeezed into a 30 wt% hydrochloric acid solution coagulation bath at a propulsion speed of 200 μL / min to obtain fibers; the fibers are washed with deionized water until neutral, and dried at -80°C for 4 h to obtain full-pore regenerated cellulose sponge fibers (with an average diameter of approximately 40 μm).

[0055] Example 2

[0056] A method for preparing full-pore regenerated cellulose sponge fiber comprises the following steps:

[0057] S1. Place 45g of sodium hydroxide and 80g of urea in a beaker, add 500g of water, and precool to obtain a mixed solution after complete dissolution;

[0058] S2, adding cotton linters to the mixture and stirring for 5 minutes to obtain a cellulose solution with a mass concentration of 6%;

[0059] S3, centrifuging the cellulose solution at 6000 rpm for 60 min to obtain a supernatant;

[0060] S4. Take 200 mL of the supernatant and mix it with 5 mL of epichlorohydrin, then react it at 0°C for 2 h to obtain a spinning solution. The spinning solution is wet-spun using a spinneret with a pore size of 0.5 mm. The spinning solution is squeezed into a 70 wt% hydrochloric acid solution coagulation bath at a propulsion speed of 800 μL / min to obtain fibers; the fibers are washed with deionized water until neutral, and dried at -60°C for 4 h to obtain full-pore regenerated cellulose sponge fibers (with an average diameter of approximately 250 μm).

[0061] Example 3

[0062] A method for preparing fully porous regenerated cellulose sponge fiber comprises the following steps:

[0063] S1. Place 40g of sodium hydroxide and 75g of urea in a beaker, add 400g of water, and precool to obtain a mixed solution after complete dissolution;

[0064] S2, adding cotton linters to the mixture and stirring for 3 minutes to obtain a cellulose solution with a mass concentration of 5%;

[0065] S3, centrifuging the cellulose solution at 10,000 rpm for 30 min to obtain a supernatant;

[0066] S4. Take 200 mL of the supernatant and mix it with 3 mL of epichlorohydrin, then react it at 6°C for 1 hour to obtain a spinning solution, and wet-spin the spinning solution. Use a spinneret with a pore size of 0.3 mm to squeeze the spinning solution into a 50 wt% hydrochloric acid solution coagulation bath at a propulsion speed of 500 μL / min to obtain fibers; wash the fibers with deionized water until neutral, and dry them at -90°C for 1 hour to obtain full-pore regenerated cellulose sponge fibers (average diameter of about 150 μm).

[0067] Example 4

[0068] A method for preparing fully porous regenerated cellulose sponge fiber comprises the following steps:

[0069] S1. Place 40 g of lithium hydroxide and 75 g of urea in a beaker, add 400 g of water, and precool to obtain a mixed solution after complete dissolution;

[0070] S2, adding cotton linters to the mixture and stirring for 4 minutes to obtain a cellulose solution with a mass concentration of 4%;

[0071] S3, centrifuging the cellulose solution at 7000 rpm for 50 min to obtain a supernatant;

[0072] S4. Take 100 mL of the supernatant and mix it with 1 mL of epichlorohydrin, then react it at 0°C for 2 h to obtain a spinning solution. The spinning solution is wet-spun using a spinneret with a pore size of 0.2 mm. The spinning solution is squeezed into a 40 wt% hydrochloric acid solution coagulation bath at a propulsion speed of 300 μL / min to obtain fibers; the fibers are washed with deionized water until neutral, and dried at -70°C for 3.5 h to obtain full-pore regenerated cellulose sponge fibers (with an average diameter of approximately 100 μm).

[0073] Comparative Example 1

[0074] A method for preparing biomass fibers with a gradient structure of "dense outside and sparse inside" comprises the following steps:

[0075] S1. Place 40 g of lithium hydroxide and 75 g of urea in a beaker, add 400 g of water, and precool to obtain a mixed solution after complete dissolution;

[0076] S2, adding cotton linters to the mixture and stirring for 4 minutes to obtain a cellulose solution with a mass concentration of 4%;

[0077] S3, centrifuging the cellulose solution at 8000 rpm for 50 min to obtain a supernatant;

[0078] S4. Take 100 mL of the supernatant and mix it with 1 mL of epichlorohydrin, then react it at 4°C for 2 hours to obtain a spinning solution. The spinning solution is wet-spun using a spinneret with a pore size of 0.2 mm. The spinning solution is squeezed into a 5 wt% sulfuric acid solution coagulation bath at a propulsion speed of 300 μL / min to obtain fibers; the fibers are washed with deionized water until neutral, and dried at -80°C for 4 hours to obtain gradient structure "dense outside and sparse inside" biomass fibers (with an average diameter of approximately 110 μm).

[0079] Comparative Example 2

[0080] A method for preparing a biomass fiber with a gradient structure of "dense outside and dense inside" comprises the following steps:

[0081] S1. Place 40g of sodium hydroxide and 75g of urea in a beaker, add 400g of water, and precool to obtain a mixed solution after complete dissolution;

[0082] S2, adding cotton linters to the mixture and stirring for 3 minutes to obtain a cellulose solution with a mass concentration of 5%;

[0083] S3, centrifuging the cellulose solution at 8000 rpm for 50 min to obtain a supernatant;

[0084] S4. Take 200 mL of the supernatant and mix it with 3 mL of epichlorohydrin, then react it at 4°C for 2 hours to obtain a spinning solution. The spinning solution is wet-spun using a spinneret with a pore size of 0.3 mm. The spinning solution is squeezed into a 30 wt% sulfuric acid solution coagulation bath at a propulsion speed of 300 μL / min to obtain fibers; the fibers are washed with deionized water until neutral, and dried at -60°C for 4 hours to obtain gradient structure "dense outside and dense inside" biomass fibers (average diameter is about 80 μm).

[0085] Comparative Example 3

[0086] A method for preparing a fiber with a gradient structure of "sparse outside and dense inside" comprises the following steps:

[0087] S1. Mix lithium hydroxide, urea, and water in a mass ratio of 8:15:77 to obtain a mixed solution;

[0088] S2. Add cotton linters to the mixture and stir for 4 minutes to obtain 100 g of cellulose solution with a mass concentration of 5%;

[0089] S3, centrifuging the cellulose solution at 8000 rpm for 50 min to obtain a supernatant;

[0090] S4. Take 150 mL of the supernatant and mix it with 2 mL of epichlorohydrin, then react it at 4°C for 2 h to obtain a spinning solution. The spinning solution is wet-spun and microfluidic-spun. A spinneret with a pore size of 0.3 mm is used to squeeze the spinning solution at a propulsion speed of 500 μL / min. At the same time, the first sheath flow and the second sheath flow are respectively introduced into an alkali-urea solvent and a 10 wt% sulfuric acid solution to obtain fibers; the fibers are washed with deionized water until neutral, and dried at -90°C for 1 h to obtain gradient structure "sparse outside and dense inside" fibers.

[0091] Performance Characterization

[0092] Figure 1 This is the SEM image of the fully porous regenerated cellulose sponge fiber prepared in Example 1. Figure 1 It can be seen that the prepared fiber surface has a uniform full-pore structure;

[0093] Figure 2 This is the SEM image of the fully porous regenerated cellulose sponge fiber prepared in Example 2. Figure 2 It can be seen that the prepared fiber surface has a uniform full-pore structure;

[0094] Figure 3 This is the SEM image of the fully porous regenerated cellulose sponge fiber prepared in Example 3. Figure 3 It can be seen that the prepared fiber surface has a uniform full-pore structure;

[0095] Figure 4 This is the SEM image of the fully porous regenerated cellulose sponge fiber prepared in Example 4. Figure 4 It can be seen that the prepared fiber surface has a uniform full-pore structure;

[0096] Figure 5 The cross-section (left) and surface (right) morphology of the gradient structure "dense outside and sparse inside" biomass fiber prepared in Comparative Example 1. Figure 5 It can be seen that the prepared fiber has a thick and dense cortex and the internal pore structure is also relatively dense;

[0097] Figure 6 The cross-section (left) and cross-section magnification (right) morphology of the gradient structure "outer dense and inner dense" biomass fiber prepared in Comparative Example 2. Figure 6 It can be seen that the prepared fibers are highly dense inside and outside;

[0098] Figure 7 This is the SEM image of the gradient structure "outside sparse inside" fiber prepared in Comparative Example 3. Figure 7 The prepared fiber has a relatively loose outer layer and a relatively dense core layer.

[0099] Performance Testing

[0100] 1. The thermal conductivity of the fully porous regenerated cellulose sponge fiber of Example 1 was tested by a heat flow method and was found to be 0.024 (W / (m·K)), which proves that the fully porous regenerated cellulose sponge fiber has a good thermal insulation effect and can be used as a thermal barrier material.

[0101] 2. The fully porous regenerated cellulose sponge fiber prepared in Example 2 was loaded with LiCl and its water absorption rate was measured to be 180% of its own weight, which proves that the fully porous regenerated cellulose sponge fiber as a substrate can provide a large amount of storage space for water and has good prospects in fields such as seawater desalination.

[0102] 3. The water transmission rate of the fully porous regenerated cellulose sponge fiber prepared in Example 3 can reach 800 μm / s by doping with carbon materials, which proves that the fully porous regenerated cellulose sponge fiber as a substrate can provide strong power generation capacity and enhance the hydrovoltaic effect, and has good application prospects in the field of hydrovoltaic power generation.

[0103] 4. The fully porous regenerated cellulose sponge fiber prepared in Example 4 was loaded with drugs, demonstrating a drug loading efficiency exceeding 81% and a sustained-release duration exceeding 22 hours. Therefore, this fully porous regenerated cellulose sponge fiber is a promising multifunctional drug carrier with great potential for tablet miniaturization, drug abuse deterrence, and sustained and controlled drug release.

[0104] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0105] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing full-pore regenerated cellulose sponge fiber, characterized in that: The following steps are involved: S1, mixing alkali, urea and water to obtain a mixed solution; S2, mixing the mixed solution with cotton linters to obtain a cellulose solution; S3, centrifuging the cellulose solution to obtain a supernatant; S4, wet-spinning the supernatant to obtain fully porous regenerated cellulose sponge fibers; In step S4, the supernatant is first mixed with a cross-linking agent and reacted to obtain a spinning solution, and then wet spinning is performed; The cross-linking agent is epichlorohydrin; In step S4, the wet spinning parameters are as follows: the pore size of the spinneret is 0.05-0.5 mm, the single hole flow rate is 200-800 μL / min, and the coagulation bath is a hydrochloric acid aqueous solution with a mass concentration of 30-70%.

2. The preparation method according to claim 1, characterized in that In step S1, the mass ratio of alkali, urea and water is 30-50:60-80:350-500.

3. The preparation method according to claim 1 or 2, characterized in that In step S1, the base is sodium hydroxide or lithium hydroxide.

4. The preparation method according to claim 3, characterized in that In step S2, the mass concentration of cotton linters in the cellulose solution is 3-6%; the mixing is carried out by stirring for 1-5 minutes.

5. The preparation method according to claim 1, 2 or 4, characterized in that: In step S3, the centrifugal speed is 5000-10000 rpm, and the centrifugal time is 20-60 min.

6. The preparation method according to claim 5, characterized in that The volume ratio of the supernatant to the cross-linking agent is 50-200:1-5; the reaction temperature is 0-10° C., and the reaction time is 1-3 hours.

7. Full-porous regenerated cellulose sponge fiber prepared by the preparation method according to any one of claims 1 to 6.

8. Use of the fully porous regenerated cellulose sponge fiber according to claim 7 in electronic components, photothermal conversion materials, osmotic energy conversion materials, seawater desalination materials or biomedical polymer materials.

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