A skin-core gradient non-silver antibacterial regenerated cellulose fiber and a preparation method thereof
By designing a core-sheath gradient structure and functional components, the problem of uneven distribution of antibacterial components in regenerated cellulose fibers was solved, improving antibacterial performance and spinning stability while maintaining the mechanical properties of the fibers.
Patent Information
- Application Number
- CN202611022950.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-10
- Publication Date
- 2026-11-03
AI Technical Summary
The antibacterial components of existing regenerated cellulose fibers are unevenly distributed in the fiber cross-section, resulting in low utilization efficiency per unit amount, poor washability and spinning stability, and easy loss during post-processing, which affects the mechanical properties of the fibers.
Employing a core-shell gradient structure, the shell liquid and core liquid are prepared separately. The shell liquid contains quaternized chitosan, halloysite nanotubes, catecholized chitosan, and quaternized polysilsesquioxane nanoparticles. These are simultaneously extruded through a coaxial spinneret to form regenerated cellulose fibers with a core-shell structure. The functional components of the shell are distributed in a decreasing manner from the outside to the inside.
It improves the surface utilization rate of antibacterial components and the antibacterial retention rate after washing, reduces the migration and loss of functional components during post-treatment, and improves spinning stability and fiber mechanical properties.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of regenerated cellulose fiber technology, specifically to a core-sheath gradient non-silver antibacterial regenerated cellulose fiber and its preparation method. Background Technology
[0002] Regenerated cellulose fibers possess excellent moisture absorption, breathability, skin-friendliness, and spinnability, making them widely used in hygiene products, home textiles, apparel fabrics, and medical textiles. To impart antibacterial properties to regenerated cellulose fibers, current techniques typically involve directly adding antibacterial components to the spinning solution for blending and spinning. While this method can impart antibacterial properties to the fibers to some extent, it still has some limitations.
[0003] First, antibacterial components are typically distributed relatively uniformly across the fiber cross-section. Functional components located in the fiber's central region are less likely to fully participate in surface contact antibacterial activity, resulting in low utilization efficiency per unit amount. Second, functional components are prone to migration and loss during coagulation, washing, drafting, desulfurization, and finishing processes, leading to decreased wash resistance and process stability. Third, increasing the amount of functional components added to maintain a high antibacterial rate often results in decreased spinning solution stability, filtration difficulties, poor spinneret flow, increased fiber breakage, and decreased fiber mechanical properties.
[0004] Existing technologies include methods for directly adding quaternized chitosan to viscose spinning solution and then wet spinning to obtain antibacterial regenerated cellulose fibers. While this method can achieve initial antibacterial activity, because the functional components are relatively uniformly distributed within the fiber cross-section, the functional components located in the fiber's central region are difficult to effectively participate in surface contact antibacterial activity. Furthermore, during acid coagulation, washing, and finishing processes, they tend to migrate and seep out along the concentration gradient, making it difficult to simultaneously improve the density of effective surface sites and the antibacterial retention rate after washing.
[0005] In homogeneous blending systems, after functional particles or polyelectrolytes are dispersed within the fiber cross-section, the components located in the central region cannot effectively participate in contact antibacterial activity. At the same time, during acid coagulation and subsequent washing, these components are also prone to migrate and seep out along the concentration gradient, making it difficult to simultaneously improve the surface effective site density and wash resistance retention rate.
[0006] While existing technologies have outlined core-shell structures that arrange functional components on the fiber surface, and have also disclosed the use of nano-inorganic carriers, interfacial adhesive components, and organosilicon cationic phases in antibacterial materials, there is still a lack of a complete technical solution that can synergistically confine cationic antibacterial polymers, inorganic nanocarriers, interfacial anchoring components, and low-migration organic-inorganic cationic nanophases in a continuous phase system of regenerated cellulose, and form a gradually decreasing distribution from the surface to the inside through coaxial wet spinning, thereby taking into account antibacterial properties, washability, spinning stability, and mechanical properties.
[0007] Therefore, it is still necessary to provide a new non-silver antibacterial regenerated cellulose fiber structure and its preparation method to improve the surface utilization rate of functional components, reduce their loss during post-processing, and take into account the spinnability and comprehensive performance of the fiber. Summary of the Invention
[0008] The purpose of this invention is to provide a core-sheath gradient non-silver antibacterial regenerated cellulose fiber and its preparation method, in order to solve the problems of insufficient utilization of functional components, low washability, easy loss during post-processing, and the adverse effects of high addition amount on spinnability and mechanical properties in existing blended antibacterial regenerated cellulose fibers.
[0009] To achieve the above objectives, the present invention provides a method for preparing core-sheath gradient non-silver antibacterial regenerated cellulose fibers, comprising the following steps:
[0010] Step (1) Prepare the shell base liquid and the core liquid respectively. The shell base liquid is a regenerated cellulose spinning solution and the core liquid is a regenerated cellulose spinning solution.
[0011] Step (2) Premix halloysite nanotubes with a portion of quaternized chitosan, and add the premix, catecholized chitosan and quaternized polysilsesquioxane nanoparticles to the shell base liquid to obtain the shell liquid;
[0012] Step (3) Use a coaxial spinneret to simultaneously extrude the shell liquid and core liquid and introduce them into a coagulation bath for wet spinning;
[0013] Step (4) After the fiber solidifies, it is washed with water, stretched, desulfurized, oiled and dried in sequence to obtain the core-sheath gradient non-silver antibacterial regenerated cellulose fiber.
[0014] Furthermore, both the shell liquid and the core liquid use regenerated cellulose as the continuous phase; the resulting fiber has a core-shell structure, and the functional components in the shell layer show a distribution trend of decreasing from the outer surface of the fiber to the inside of the fiber. Moreover, the shell liquid, the core liquid, and the resulting fiber do not contain elemental silver, silver salts, or silver-containing inorganic antibacterial agents as antibacterial active ingredients.
[0015] Preferably, the shell liquid is a regenerated cellulose spinning solution, wherein the α-cellulose content in the shell liquid is 8.0%–8.4%, and the total alkali content is 5.1%–5.4%; based on 100 parts by mass of shell α-cellulose, the shell liquid contains 2.8–3.5 parts by mass of quaternized chitosan, 0.8–1.5 parts by mass of halloysite nanotubes, 0.20–0.50 parts by mass of catecholized chitosan, and 0.40–0.80 parts by mass of quaternized polysilsesquioxane nanoparticles; the core liquid contains 8.4%–8.8% α-cellulose, has a total alkali content of 4.8%–5.2%, and does not contain quaternized chitosan, halloysite nanotubes, catecholized chitosan, or quaternized polysilsesquioxane nanoparticles.
[0016] Preferably, before adding the shell liquid, the halloysite nanotubes are first dispersed in an aqueous dispersion system containing polysorbate-80 for 20-40 min, and then centrifuged, washed, dried and pulverized to obtain carrier powder; the premixed mass ratio of halloysite nanotubes to quaternized chitosan is 20:1 to 5:1; the average length of the halloysite nanotubes is 0.2-1.0 μm, the inner diameter is 10-30 nm, and the outer diameter is 30-50 nm.
[0017] Preferably, in step (3), the viscosity ratio of the shell liquid to the core liquid at 20°C is 0.98 to 1.02, and the mass flow ratio of the shell liquid to the core liquid is 1:5 to 1:3; the coagulation bath temperature is 42 to 46°C, and the concentration of sulfuric acid in the coagulation bath is 95 to 105 g / L, the concentration of sodium sulfate is 260 to 290 g / L, and the concentration of zinc sulfate is 20 to 28 g / L.
[0018] Preferably, in step (4), the total draw ratio is 90% to 120%, the sodium sulfite concentration in the desulfurization liquid is 8 to 12 g / L, the degree of quaternization of the quaternized chitosan is 15% to 35%, the degree of catechin substitution of the catechinized chitosan is 5% to 20%, and the average particle size of the quaternized polysilsesquioxane nanoparticles is 60 to 100 nm.
[0019] This invention also provides a core-shell gradient non-silver antibacterial regenerated cellulose fiber, comprising a core layer and a shell layer; wherein, both the core layer and the shell layer are composed of regenerated cellulose as the sole continuous phase, the shell layer contains quaternized chitosan, halloysite nanotubes, catecholized chitosan, and quaternized polysilsesquioxane nanoparticles, the core layer is a regenerated cellulose layer that does not contain the quaternized chitosan, halloysite nanotubes, catecholized chitosan, and quaternized polysilsesquioxane nanoparticles, and the functional components in the shell layer exhibit a distribution trend of decreasing overall from the fiber outer surface to the fiber interior, and the fiber does not contain elemental silver, silver salts, or silver-containing inorganic antibacterial agents as antibacterial active ingredients.
[0020] Preferably, the shell thickness accounts for 10% to 16% of the fiber radius; based on 100 parts by weight of shell α-cellulose, the shell contains 2.8 to 3.5 parts by weight of quaternized chitosan, 0.8 to 1.5 parts by weight of halloysite nanotubes, 0.20 to 0.50 parts by weight of catecholized chitosan, and 0.40 to 0.80 parts by weight of quaternized polysilsesquioxane nanoparticles.
[0021] Preferably, the halloysite nanotubes in the shell are premixed with quaternized chitosan at a mass ratio of 20:1 to 5:1; the degree of quaternization of the quaternized chitosan is 15% to 35%; and the degree of catechin substitution of the catechinized chitosan is 5% to 20%.
[0022] Preferably, the average particle size of the quaternized polysilsesquioxane nanoparticles is 60-100 nm; and the amount of the quaternized polysilsesquioxane nanoparticles added is 0.50-0.70 parts by mass per 100 parts by mass of shell α-cellulose.
[0023] Preferably, the shell thickness accounts for 12% to 14% of the fiber radius.
[0024] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:
[0025] 1. This invention employs a core-shell structure of regenerated cellulose core and a regenerated cellulose shell containing a quaternary functional system, and makes the functional components in the shell exhibit a distribution trend of decreasing from the outer surface of the fiber to the inside of the fiber. This allows the antibacterial functional phase to be preferentially concentrated in the outer layer of the fiber and maintain a high degree of proximity to the fiber surface, thereby improving the surface utilization rate of the antibacterial components and improving the antibacterial retention rate after washing.
[0026] 2. This invention simultaneously incorporates quaternized chitosan, halloysite nanotubes, catecholized chitosan, and quaternized polysilsesquioxane nanoparticles within the shell layer. Quaternized chitosan provides cationic antibacterial sites, halloysite nanotubes provide a carrier and diffusion hindrance, catecholized chitosan enhances the interfacial anchoring between the functional phase and the regenerated cellulose matrix and inorganic phase, and quaternized polysilsesquioxane nanoparticles provide a low-migration organic-inorganic cationic nanophase. This reduces the migration and loss of functional components during coagulation, washing, and desulfurization processes, improves the retention rate of characteristic elements such as N and Si in the shell layer, and enhances wash resistance stability.
[0027] 3. This invention employs a system in which both the shell liquid and the core liquid are continuous phases of regenerated cellulose. By matching the shell and core viscosity, matching the shell and core flow rate, and controlling the coaxial wet spinning process, it helps to form a shell-core structure with a clear interface, continuous shell, and controllable thickness. This reduces shell breakage, local missing parts, obvious eccentricity, and continuous agglomeration, thereby improving the stability of continuous spinning. It also maintains good dry strength, wet strength, and elongation at break while ensuring antibacterial and wash-resistant properties. Attached Figure Description
[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0029] Figure 1 This is a process flow diagram of the preparation process of the core-sheath gradient non-silver antibacterial regenerated cellulose fiber of the present invention;
[0030] Figure 2 This is a comparison diagram of the surface enrichment characteristics of different samples of the non-silver antibacterial regenerated cellulose fiber with sheath-core gradient according to the present invention;
[0031] Figure 3 This is a comparison chart of the antibacterial rate of the non-silver antibacterial regenerated cellulose fiber with sheath-core gradient after 50 washes according to the present invention.
[0032] Figure 4 This is a comparison chart of element retention rates after 20 washes of the non-silver antibacterial regenerated cellulose fiber with sheath-core gradient according to the present invention. Detailed Implementation
[0033] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0034] The chitosan used in this embodiment has a degree of deacetylation of 85% and a viscosity-average molecular weight of approximately 1.6 × 10⁻⁶. 5 Glycidyltrimethylammonium chloride is of industrial grade. Halloysite nanotubes have an average length of approximately 0.5 μm, an inner diameter of approximately 18 nm, and an outer diameter of approximately 42 nm. Quaternized polysilsesquioxane nanoparticles are preferably a self-made nanoparticle system, with an average particle size determined by dynamic light scattering, preferably 60–100 nm, and a PDI of less than 0.15.
[0035] The quaternized polysilsesquioxane nanoparticles can be prepared as follows: First, 3-glycidoxypropyltrimethoxysilane and N,N-dimethyloctadecylamine are added to isopropanol at a molar ratio of 1:1 to 1.2, and the solid content is controlled at 20% to 35%. The mixture is reacted at 70°C for 3 hours to obtain a quaternized silane intermediate. Then, deionized water and ethanol are mixed at a volume ratio of 3:7, a composite emulsifier is added, and the pH of the system is adjusted to 4.0 to 4.5. The composite emulsifier is polysorbate-80 and Span-80, and the total amount added is 1.0% to 3.0% of the total mass of the mixed solvent. After pre-stirring at 10 to 25°C for 2 hours, methyltrimethoxysilane and the quaternized silane intermediate are added dropwise at a rate of 20 drops / min. After the addition is completed, the reaction continues for 8 to 12 hours. After centrifugation to remove large particles and dialysis or washing to remove small molecules, a dispersion of quaternized polysilsesquioxane nanoparticles is obtained. The resulting dispersion preferably has a solid content of 8% to 15% and an average particle size of 60 to 100 nm.
[0036] The apparent viscosities of the shell fluid and core fluid were measured using a rotational rheometer at 20°C with a shear rate of 10 s⁻¹. -1 In the embodiments, the apparent viscosity of the shell liquid can be controlled at 90–96 Pa·s, and the apparent viscosity of the core liquid can be controlled at 92–97 Pa·s.
[0037] The experimental core-shell composite nozzle structure used has the following characteristics: nozzle body height is 9 mm, diameter is 7 mm; core layer filament outlet diameter is 0.5 mm, and shell layer filament outlet diameter is 1.3 mm; core layer spinneret main flow channel straight section outer diameter is 3.5 mm, and shell layer spinneret branch flow channel straight section inner diameter is 4.3 mm. Both shell layer and core layer fluids are filtered through a 5 μm filter before use.
[0038] The desulfurization temperature of this invention is 60-70℃, the water washing temperature is around 50℃, the oiling temperature is 40-45℃, and the drying temperature can be 135-155℃, preferably 135-145℃. The water washing bath ratio can be 1:20, the water washing time can be 10 min; the stretching bath temperature can be 45-50℃; the oiling rate can be 0.20%-0.50%, and the drying time can be 20-30 min.
[0039] The degree of quaternization of quaternized chitosan is preferably determined by elemental analysis, nuclear magnetic resonance (NMR), or potentiometric titration; the degree of catechol substitution of catecholized chitosan is preferably determined by ultraviolet spectrophotometry, NMR, or Folin-Ciocalteu colorimetry. If NMR is used, the degree of quaternization or catechol substitution is calculated based on the ratio of the integral area of the characteristic peak to the integral area of the characteristic peak of the chitosan backbone.
[0040] Preparation Example 1
[0041] This preparation example discloses a method for preparing quaternized chitosan, including the following steps:
[0042] Ten parts by mass of chitosan were added to 600 parts by volume of 1% acetic acid aqueous solution and stirred at 60°C until completely dissolved. 28 parts by mass of glycidyltrimethylammonium chloride were added and the reaction was continued at 60°C for 18 hours. After the reaction was completed, the reaction solution was placed in a dialysis bag and dialyzed in deionized water for 60 hours, with the water changed regularly during the process. After dialysis, the solution was freeze-dried to obtain quaternized chitosan.
[0043] Preparation Example 2
[0044] This preparation example discloses a method for preparing halloysite nanotube carrier powder, including the following steps:
[0045] 300 parts by volume of deionized water were heated to 60°C, and 0.30 parts by mass of polysorbate-80 were added. After mixing, 30 parts by mass of halloysite nanotubes were gradually added at 100 rpm. The mixture was shaken and dispersed for 35 min. After centrifugation, the mixture was washed three times with distilled water and dried at 100°C for 15 h. The mixture was then pulverized and sieved to obtain the carrier powder. Subsequently, the carrier powder was premixed with quaternized chitosan at a mass ratio of 10:1. The quaternized chitosan used in the premixing step was included in the total amount of quaternized chitosan added to the shell layer.
[0046] Preparation Example 3
[0047] This preparation example discloses a method for preparing catecholized chitosan, including the following steps:
[0048] One part by mass of chitosan was dissolved in a weakly acidic aqueous solution, and 0.4 parts by mass of 3,4-dihydroxyphenylacetic acid, 0.3 parts by mass of N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride and 0.15 parts by mass of N-hydroxysuccinimide were added. The mixture was reacted at room temperature for 12 hours. The reaction solution was dialyzed and freeze-dried to obtain catecholized chitosan.
[0049] Preparation Example 4
[0050] This preparation example discloses a method for preparing quaternized polysilsesquioxane nanoparticles, including the following steps:
[0051] S1: 1.00 mol of 3-glycidoxypropyltrimethoxysilane and 1.05 mol of N,N-dimethyloctadecylamine were added to isopropanol, the solid content of the system was controlled at 30%, and the reaction was stirred at 70°C for 3 h to obtain the quaternized silane intermediate.
[0052] S2: Mix ethanol and deionized water at a volume ratio of 7:3, add 1.5% polysorbate-80 and 0.5% Span-80 by mass of the total mixed solvent, adjust the pH of the system to 4.2 with glacial acetic acid, and stir at 15°C for 2 hours;
[0053] S3: While maintaining stirring at 15°C, methyltrimethoxysilane and the quaternized silane intermediate obtained in step S1 were added dropwise at a rate of 20 drops / min, with a total molar ratio of 1:0.15; after the addition was completed, the reaction continued for 10 hours.
[0054] S4: The reaction solution was centrifuged at 8000 rpm for 10 min to remove large particles, and then dialyzed with deionized water for 48 h to obtain a quaternized polysilsesquioxane nanoparticle dispersion.
[0055] S5: The average particle size of the obtained nanoparticles was approximately 82 nm, and the PDI was less than 0.15, as measured by dynamic light scattering.
[0056] Example 1
[0057] This embodiment discloses a method for preparing a core-sheath gradient non-silver antibacterial regenerated cellulose fiber, comprising the following steps:
[0058] Step (1) The α-cellulose content in the shell liquid is 7.2%, and the total alkali content is 4.6%; based on 100 parts by mass of shell α-cellulose, 1.2 parts by mass of quaternized chitosan, 0.3 parts by mass of halloysite nanotubes, 0.08 parts by mass of catecholized chitosan and 0.15 parts by mass of quaternized polysilsesquioxane nanoparticles are added to the shell liquid.
[0059] The core layer solution is a conventional regenerated cellulose spinning solution with an α-cellulose content of 7.8% and a total alkali content of 4.3%, without the aforementioned functional components added.
[0060] Step (2) Premix halloysite nanotubes with a portion of quaternized chitosan and then add them to the shell liquid.
[0061] The halloysite nanotubes were added in the form of a premixed carrier powder of halloysite nanotubes obtained in Preparation Example 2. Based on 100 parts by mass of shell α-cellulose, the amount of halloysite nanotubes added in the premixed carrier powder was equivalent to 0.3 parts by mass, and the corresponding amount of quaternized chitosan introduced in the premix was 0.03 parts by mass, which was included in the total amount of quaternized chitosan added to the shell liquid. The remaining 1.17 parts by mass of quaternized chitosan were added using the quaternized chitosan obtained in Preparation Example 1. The catecholized chitosan was the product obtained in Preparation Example 3, and the quaternized polysilsesquioxane nanoparticles were the dispersion obtained in Preparation Example 4. The shell liquid was obtained after high-speed dispersion, filtration, and degassing.
[0062] Step (3) Use a coaxial spinneret to simultaneously extrude the shell liquid and core liquid and introduce them into the coagulation bath for wet spinning.
[0063] The viscosity ratio of the shell liquid to the core liquid was controlled at 0.92, and the mass flow rate ratio of the shell liquid to the core liquid was 1:6. The coagulation bath temperature was 38℃, and the concentration of sulfuric acid was 85 g / L, sodium sulfate was 230 g / L, and zinc sulfate was 12 g / L.
[0064] Step (4) After the fiber solidifies, it is washed with water, stretched, desulfurized, oiled and dried in sequence to obtain the core-sheath gradient non-silver antibacterial regenerated cellulose fiber.
[0065] The total draw ratio is 50%, and the sodium sulfite concentration in the desulfurization solution is 6 g / L.
[0066] Example 2
[0067] This embodiment discloses a method for preparing a core-sheath gradient non-silver antibacterial regenerated cellulose fiber, which is basically the same as that in Example 1, except that:
[0068] Step (1) The α-cellulose content in the shell liquid is 8.0%, and the total alkali content is 5.2%. Based on 100 parts by mass of shell α-cellulose, 3.0 parts by mass of quaternized chitosan, 1.0 parts by mass of halloysite nanotubes, 0.30 parts by mass of catecholized chitosan and 0.50 parts by mass of quaternized polysilsesquioxane nanoparticles are added to the shell liquid. After high-speed dispersion, filtration and degassing, the shell liquid is obtained.
[0069] The core liquid contains 8.5% α-cellulose and 5.0% total alkali, without the aforementioned functional components.
[0070] Step (2) Premix halloysite nanotubes with a portion of quaternized chitosan and then add them to the shell liquid.
[0071] In this embodiment, the halloysite nanotubes were added in the form of a premixed carrier powder of halloysite nanotubes obtained in Preparation Example 2. Based on 100 parts by mass of shell α-cellulose, the amount of halloysite nanotubes added in the premixed carrier powder was equivalent to 1.0 parts by mass, and the corresponding amount of quaternized chitosan introduced in the premix was 0.10 parts by mass, which was included in the total amount of quaternized chitosan added to the shell liquid. The remaining 2.90 parts by mass of quaternized chitosan were added using the quaternized chitosan obtained in Preparation Example 1. The catecholized chitosan was the product obtained in Preparation Example 3, and the quaternized polysilsesquioxane nanoparticles were the dispersion obtained in Preparation Example 4.
[0072] Step (3) Use a coaxial spinneret to simultaneously extrude the shell liquid and core liquid and introduce them into the coagulation bath for wet spinning.
[0073] The viscosity ratio of the shell liquid to the core liquid was controlled at 0.98, and the mass flow rate ratio of the shell liquid to the core liquid was 1:5. The coagulation bath temperature was 45℃, and the concentration of sulfuric acid was 100 g / L, sodium sulfate was 280 g / L, and zinc sulfate was 25 g / L.
[0074] Step (4) After the fiber solidifies, it is washed with water, stretched, desulfurized, oiled and dried in sequence to obtain the core-sheath gradient non-silver antibacterial regenerated cellulose fiber.
[0075] The total draw ratio is 100%, and the sodium sulfite concentration in the desulfurization solution is 10 g / L.
[0076] Example 3
[0077] This embodiment discloses a method for preparing a core-sheath gradient non-silver antibacterial regenerated cellulose fiber, which is basically the same as that in Example 1, except that:
[0078] Step (1) The α-cellulose content in the shell liquid is 8.8%, and the total alkali content is 5.8%. Based on 100 parts by mass of shell α-cellulose, 5.0 parts by mass of quaternized chitosan, 2.0 parts by mass of halloysite nanotubes, 0.80 parts by mass of catecholized chitosan and 1.20 parts by mass of quaternized polysilsesquioxane nanoparticles are added to the shell liquid. After high-speed dispersion, filtration and degassing, the shell liquid is obtained.
[0079] The core liquid contains 9.0% α-cellulose and 5.3% total alkali, without the aforementioned functional components.
[0080] Step (2) Premix halloysite nanotubes with a portion of quaternized chitosan and then add them to the shell liquid.
[0081] In this embodiment, the halloysite nanotubes were added in the form of a premixed carrier powder of halloysite nanotubes obtained in Preparation Example 2. Based on 100 parts by mass of shell α-cellulose, the amount of halloysite nanotubes added in the premixed carrier powder was equivalent to 2.0 parts by mass, and the corresponding amount of quaternized chitosan introduced in the premix was 0.20 parts by mass, which was included in the total amount of quaternized chitosan added to the shell liquid. The remaining 4.80 parts by mass of quaternized chitosan were added using the quaternized chitosan obtained in Preparation Example 1. The catecholized chitosan was the product obtained in Preparation Example 3, and the quaternized polysilsesquioxane nanoparticles were the dispersion obtained in Preparation Example 4.
[0082] Step (3) Use a coaxial spinneret to simultaneously extrude the shell liquid and core liquid and introduce them into the coagulation bath for wet spinning.
[0083] The viscosity ratio of the shell liquid to the core liquid was controlled at 0.96, and the mass flow rate ratio of the shell liquid to the core liquid was 1:3. The coagulation bath temperature was 48℃, and the concentration of sulfuric acid was 110 g / L, sodium sulfate was 300 g / L, and zinc sulfate was 30 g / L.
[0084] Step (4) After the fiber solidifies, it is washed with water, stretched, desulfurized, oiled and dried in sequence to obtain the core-sheath gradient non-silver antibacterial regenerated cellulose fiber.
[0085] The total draw ratio is 140%, and the sodium sulfite concentration in the desulfurization solution is 15 g / L.
[0086] Example 4
[0087] This embodiment discloses a method for preparing a core-sheath gradient non-silver antibacterial regenerated cellulose fiber, which is basically the same as that in Example 1, except that:
[0088] Step (1) The α-cellulose content in the shell liquid is 8.2%, and the total alkali content is 5.3%. Based on 100 parts by mass of shell α-cellulose, 3.2 parts by mass of quaternized chitosan, 1.2 parts by mass of halloysite nanotubes, 0.35 parts by mass of catecholized chitosan and 0.60 parts by mass of quaternized polysilsesquioxane nanoparticles are added to the shell liquid. After high-speed dispersion, filtration and degassing, the shell liquid is obtained.
[0089] The core liquid contains 8.6% α-cellulose, 5.0% total alkali, and 0% total functional additives.
[0090] Step (2) Premix halloysite nanotubes with a portion of quaternized chitosan and then add them to the shell liquid.
[0091] In this embodiment, the halloysite nanotubes were added in the form of a premixed carrier powder of halloysite nanotubes obtained in Preparation Example 2. Based on 100 parts by mass of shell α-cellulose, the amount of halloysite nanotubes added in the premixed carrier powder was equivalent to 1.2 parts by mass, and the corresponding amount of quaternized chitosan introduced in the premix was 0.12 parts by mass, which was included in the total amount of quaternized chitosan added to the shell liquid. The remaining 3.08 parts by mass of quaternized chitosan were added using the quaternized chitosan obtained in Preparation Example 1. The catecholized chitosan was the product obtained in Preparation Example 3, and the quaternized polysilsesquioxane nanoparticles were the dispersion obtained in Preparation Example 4.
[0092] Step (3) Use a coaxial spinneret to simultaneously extrude the shell liquid and core liquid and introduce them into the coagulation bath for wet spinning.
[0093] The viscosity ratio of the shell liquid to the core liquid was controlled at 1.00, and the mass flow rate ratio of the shell liquid to the core liquid was 1:4. The coagulation bath temperature was 44℃, and the concentration of sulfuric acid was 100 g / L, sodium sulfate was 275 g / L, and zinc sulfate was 24 g / L.
[0094] Step (4) After the fiber solidifies, it is washed with water, stretched, desulfurized, oiled and dried in sequence to obtain the core-sheath gradient non-silver antibacterial regenerated cellulose fiber.
[0095] The total draw ratio is 110%, and the sodium sulfite concentration in the desulfurization solution is 10 g / L.
[0096] Comparative Example 1
[0097] All functional components from Example 2 were directly added to a single regenerated cellulose spinning solution in the same amount. Instead of coaxial core-sheath spinning, ordinary wet spinning was used to prepare homogeneous blended non-silver antibacterial regenerated cellulose fibers. The functional components were: 3.0 parts by weight of quaternized chitosan, 1.0 parts by weight of halloysite nanotubes, 0.30 parts by weight of catecholized chitosan, and 0.50 parts by weight of quaternized polysilsesquioxane nanoparticles, based on 100 parts by weight of α-cellulose.
[0098] Comparative Example 2
[0099] The same shell and core spinning conditions as in Example 2 were used, but halloysite nanotubes were not added to the shell solution, while other components and process conditions remained unchanged.
[0100] Comparative Example 3
[0101] The same shell and core spinning conditions as in Example 2 were used, but catechinized chitosan was not added to the shell solution, while other components and process conditions remained unchanged.
[0102] Comparative Example 4
[0103] The same shell and core spinning conditions as in Example 2 were used, but quaternized polysilsesquioxane nanoparticles were not added to the shell solution, while other components and process conditions remained unchanged.
[0104] Comparative Example 5
[0105] The same composition and formulation as in Example 2 were used, but the viscosity ratio of the shell liquid to the core liquid was adjusted to 1.20, and the mass flow ratio of the shell liquid to the core liquid was adjusted to 1:8, while the other conditions remained unchanged, in order to form a shell structure that was significantly thinner and had poorer interfacial stability.
[0106] Test methods and results:
[0107] Antibacterial properties were quantitatively tested according to GB / T 20944.3-2008, with Staphylococcus aureus and Escherichia coli as the test strains. Wash resistance was tested according to GB / T 8629-2017, with antibacterial rates tested after 20 and 50 washes. Fiber mechanical properties were tested according to GB / T 14337-2022, with dry and wet strength measured in cN / dtex. The average particle size and particle size distribution of nanoparticles were determined using dynamic light scattering, following GB / T 29022-2021; if zeta potential characterization was required, it was performed according to GB / Z 42353-2023. Shell thickness was measured using fiber cross-sectional image analysis, with 50 fibers randomly selected. The radial gradient distribution was characterized using SEM-EDS line and area scans. Nitrogen (N) was used to characterize the enrichment of quaternized chitosan and catechinized chitosan, silicon (Si) was used to characterize the enrichment of quaternized polysilsesquioxane nanoparticles, and al (Al) was used to characterize the distribution of halloysite nanotubes in the shell. The above performance data are preferably the average of three parallel experiments.
[0108] Element retention rate is calculated using the following formula:
[0109] Element retention rate (%) = Normalized signal intensity of characteristic elements in the treated sample / Normalized signal intensity of characteristic elements in the untreated sample × 100%.
[0110] The normalized signal intensity is the ratio of the peak intensity of the characteristic element to the total count intensity of the same region under the same instrument parameters, the same sampling area size, the same sampling time, and the same data processing conditions, or the ratio of the peak intensity of the characteristic element to the total peak intensity of C and O elements in the same region.
[0111] The percentage of abnormal cross sections refers to the proportion of fiber cross sections with obvious shell fractures, local missing parts, severe eccentricity, or visible continuous agglomeration areas among 50 randomly selected fiber cross sections.
[0112] The continuous spinning time and number of yarn breaks were recorded under the same spinning speed, the same liquid supply rate and the same ambient temperature and humidity conditions. The spinning speed was 10 m / min, the ambient temperature was controlled at 20±2℃ according to GB / T 6529-2008, and the relative humidity was controlled at 65±4%.
[0113] Table 1. Results of structure distribution and gradient characterization
[0114] sample Whether a core-skin structure is formed Shell thickness as a percentage of radius (%) Percentage of abnormal sections (%) N-signal in the 0–2 μm region of the surface / N-signal in the center 1 / 3 radius Si signal in the 0–2 μm region of the surface / Si signal in the center 1 / 3 radius Example 1 yes 8.3 7.6 1.67 1.54 Example 2 yes 10.9 3.8 2.21 2.03 Example 3 yes 17.4 4.4 2.83 2.49 Example 4 yes 13.8 2.1 3.08 2.91 Comparative Example 1 no — — 1.08 1.00 Comparative Example 2 yes 10.6 5.8 1.54 1.87 Comparative Example 3 yes 10.7 6.1 1.63 1.82 Comparative Example 4 yes 10.5 5.7 1.79 — Comparative Example 5 yes 5.8 19.4 1.31 1.18
[0115] Table 2 Results of antibacterial and wash resistance
[0116] sample Initial inhibition rate against Staphylococcus aureus (%) Antibacterial rate after 20 washes (%) Antibacterial rate after 50 washes (%) Initial inhibition rate against Escherichia coli (%) Antibacterial rate after 20 washes (%) Antibacterial rate after 50 washes (%) Example 1 97.34 90.82 83.67 96.91 89.46 82.11 Example 2 99.42 95.37 88.96 99.08 94.12 87.45 Example 3 99.71 95.84 89.28 99.53 95.01 88.07 Example 4 99.83 97.18 91.64 99.66 96.24 90.38 Comparative Example 1 98.88 87.76 75.84 98.43 86.19 73.92 Comparative Example 2 99.05 91.33 81.04 98.77 89.85 79.36 Comparative Example 3 99.11 90.41 79.72 98.90 88.97 78.21 Comparative Example 4 99.08 90.95 80.86 98.82 89.43 79.18 Comparative Example 5 97.81 84.63 71.34 97.26 82.94 69.57
[0117] Table 3 Results of element retention rate, mechanical properties and spinning stability
[0118] sample N retention rate after desulfurization (%) N retention rate (%) after 20 washes Si retention rate after desulfurization (%) Si retention rate (%) after 20 washes Dry strength (cN / dtex) Wet strength (cN / dtex) Elongation at break (%) Continuous spinning time (h) Number of decapitations Example 1 90.8 80.6 88.4 77.9 2.29 1.42 16.7 7.2 3 Example 2 94.1 86.4 91.2 83.1 2.38 1.51 16.0 9.4 2 Example 3 92.9 84.9 90.1 82.3 2.30 1.44 15.2 8.3 3 Example 4 96.3 89.1 94.4 87.2 2.43 1.57 15.9 10.1 1 Comparative Example 1 83.2 67.1 80.6 62.4 2.17 1.29 17.4 7.5 4 Comparative Example 2 88.6 74.3 87.5 70.6 2.31 1.40 16.3 8.2 3 Comparative Example 3 87.4 72.1 85.9 68.3 2.32 1.39 16.1 8.1 3 Comparative Example 4 88.1 75.0 — — 2.30 1.39 15.8 8.4 3 Comparative Example 5 81.9 65.8 79.2 60.5 2.11 1.25 17.1 4.3 8
[0119] As shown in Table 1, Examples 1-4 all formed relatively well-defined core-shell structures, with the shell thicknesses of Examples 2 and 4 falling within the preferred range of this invention. Although Example 3 also exhibited good surface enrichment characteristics, its shell thickness was too large, resulting in a less balanced overall performance compared to Example 4. Overall, the shell structure of Example 4 was more stable, with more pronounced surface enrichment and radial distribution characteristics of the functional components. In contrast, Comparative Example 1, due to its homogeneous blending method, did not form a well-defined core-shell structure; while Comparative Example 5 formed an outer layer, its shell was too thin and exhibited poor stability.
[0120] As shown in Table 2, Examples 2-4 all exhibited high initial antibacterial properties and maintained good antibacterial effects after washing, indicating that the present invention improves antibacterial performance while also ensuring wash resistance stability. Comparative Example 1, although exhibiting high initial antibacterial performance, showed significantly poor wash resistance retention. Comparative Examples 2-4, lacking different auxiliary functional components, showed little change in initial antibacterial performance, but their wash resistance retention rates all decreased, indicating that these auxiliary components primarily enhance the stability and wash resistance of the functional components. Comparative Example 5, due to its unstable shell structure, exhibited poor initial and post-wash antibacterial performance.
[0121] As shown in Table 3, Examples 2-4 maintained high retention rates of characteristic elements after post-treatment and washing, indicating that the functional components in the shell layer have good anti-migration stability. Meanwhile, these examples also maintained good dry strength, wet strength, and elongation at break, demonstrating that the present invention improves antibacterial durability without significantly impairing fiber mechanical properties. Example 4, in particular, exhibited superior spinning continuity and process stability, indicating a good match between its process parameters and shell structure.
[0122] Further comparison reveals that, compared to the homogeneous blending comparative example, the improvement in Example 2 lies not merely in increasing the amount of antibacterial agent added, but in enhancing surface utilization and reducing loss through core-shell layer enrichment and gradient distribution. Compared to the comparative example lacking halloysite nanotubes, halloysite nanotubes in this invention not only serve as inorganic fillers but also act as carriers and diffusion inhibitors. Compared to the comparative example lacking catecholized chitosan, catecholized chitosan helps enhance the interfacial anchoring between functional components and the matrix. Compared to the comparative example lacking quaternized polysilsesquioxane nanoparticles, these nanoparticles help improve shell integrity and wash resistance. The comparison between Example 4 and Comparative Example 5 demonstrates that core-shell viscosity matching and flow rate matching have a significant impact on shell thickness, gradient distribution, and spinning stability.
[0123] In summary, based on Tables 1 to 3 and Figures 1-4 It is understood that by co-setting quaternized chitosan, halloysite nanotubes, catecholized chitosan, and quaternized polysilsesquioxane nanoparticles in the shell of regenerated cellulose, and by combining shell-core viscosity matching and coaxial wet spinning process control, this invention can form a non-silver antibacterial regenerated cellulose fiber with a stable structure, suitable shell layer, and functional components distributed in a decreasing manner from the surface to the inside. This results in a better balance of antibacterial properties, washability, spinning stability, and mechanical properties.
[0124] It should be understood that, without departing from the spirit and essence of this invention, those skilled in the art can make various modifications and improvements to this invention, and all such modifications and improvements should fall within the protection scope of this invention.
[0125] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. All equivalent substitutions, modifications, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A method for preparing a core-sheath gradient non-silver antibacterial regenerated cellulose fiber, characterized in that, Includes the following steps: Step (1) Prepare the shell base liquid and the core liquid respectively. The shell base liquid is a regenerated cellulose spinning solution and the core liquid is a regenerated cellulose spinning solution. Step (2) Premix halloysite nanotubes with a portion of quaternized chitosan, and add the premix, catecholized chitosan and quaternized polysilsesquioxane nanoparticles to the shell base liquid to obtain the shell liquid; Step (3) Use a coaxial spinneret to simultaneously extrude the shell liquid and core liquid and introduce them into a coagulation bath for wet spinning; Step (4) After the fiber solidifies, it is washed with water, stretched, desulfurized, oiled and dried in sequence to obtain the core-sheath gradient non-silver antibacterial regenerated cellulose fiber; The shell liquid and core liquid both use regenerated cellulose as the continuous phase, and the resulting fiber has a core-shell structure. The functional components in the shell liquid show a distribution trend of decreasing from the outer surface of the fiber to the inside of the fiber. Furthermore, the shell liquid, core liquid, and the resulting fiber do not contain elemental silver, silver salts, or silver-containing inorganic antibacterial agents as antibacterial active ingredients.
2. The method for preparing core-sheath gradient non-silver antibacterial regenerated cellulose fiber according to claim 1, characterized in that, The shell liquid is a regenerated cellulose spinning solution, with an α-cellulose content of 8.0%–8.4% and a total alkali content of 5.1%–5.4%. Based on 100 parts by mass of shell α-cellulose, the shell liquid contains 2.8–3.5 parts by mass of quaternized chitosan, 0.8–1.5 parts by mass of halloysite nanotubes, 0.20–0.50 parts by mass of catecholized chitosan, and 0.40–0.80 parts by mass of quaternized polysilsesquioxane nanoparticles. The core liquid contains 8.4%–8.8% α-cellulose and 4.8%–5.2% total alkali, and does not contain quaternized chitosan, halloysite nanotubes, catecholized chitosan, or quaternized polysilsesquioxane nanoparticles.
3. The method for preparing core-sheath gradient non-silver antibacterial regenerated cellulose fiber according to claim 1, characterized in that, Before being added to the shell liquid, the halloysite nanotubes are first dispersed in an aqueous dispersion system containing polysorbate-80 for 20–40 min, and then centrifuged, washed, dried and pulverized to obtain carrier powder. The premixed mass ratio of halloysite nanotubes to quaternized chitosan is 20:1–5:
1. The average length of the halloysite nanotubes is 0.2–1.0 μm, the inner diameter is 10–30 nm, and the outer diameter is 30–50 nm.
4. The method for preparing core-sheath gradient non-silver antibacterial regenerated cellulose fiber according to claim 1, characterized in that, In step (3), the viscosity ratio of the shell liquid to the core liquid at 20°C is 0.98 to 1.02, and the mass flow ratio of the shell liquid to the core liquid is 1:5 to 1:3; the coagulation bath temperature is 42 to 46°C, and the sulfuric acid concentration in the coagulation bath is 95 to 105 g / L, the sodium sulfate concentration is 260 to 290 g / L, and the zinc sulfate concentration is 20 to 28 g / L.
5. The method for preparing core-sheath gradient non-silver antibacterial regenerated cellulose fiber according to claim 1, characterized in that, In step (4), the total draw ratio is 90% to 120%, the sodium sulfite concentration in the desulfurization liquid is 8 to 12 g / L, the degree of quaternization of the quaternized chitosan is 15% to 35%, the degree of catechin substitution of the catechinized chitosan is 5% to 20%, and the average particle size of the quaternized polysilsesquioxane nanoparticles is 60 to 100 nm.
6. A core-sheath gradient non-silver antibacterial regenerated cellulose fiber, characterized in that, The fiber comprises a core layer and a shell layer. Both the core layer and the shell layer are composed of regenerated cellulose as the sole continuous phase. The shell layer contains quaternized chitosan, halloysite nanotubes, catecholized chitosan, and quaternized polysilsesquioxane nanoparticles. The core layer is a regenerated cellulose layer that does not contain the quaternized chitosan, halloysite nanotubes, catecholized chitosan, and quaternized polysilsesquioxane nanoparticles. The functional components in the shell layer exhibit a distribution trend that generally decreases from the outer surface of the fiber to the interior of the fiber. The fiber does not contain elemental silver, silver salts, or silver-containing inorganic antibacterial agents as antibacterial active ingredients.
7. The core-sheath gradient non-silver antibacterial regenerated cellulose fiber according to claim 6, characterized in that, The shell thickness accounts for 10% to 16% of the fiber radius; based on 100 parts by weight of shell α-cellulose, the shell contains 2.8 to 3.5 parts by weight of quaternized chitosan, 0.8 to 1.5 parts by weight of halloysite nanotubes, 0.20 to 0.50 parts by weight of catecholized chitosan, and 0.40 to 0.80 parts by weight of quaternized polysilsesquioxane nanoparticles.
8. The core-sheath gradient non-silver antibacterial regenerated cellulose fiber according to claim 6, characterized in that, Halloysite nanotubes in the shell are premixed with quaternized chitosan at a mass ratio of 20:1 to 5:1; the degree of quaternization of the quaternized chitosan is 15% to 35%; and the degree of catechin substitution of the catechinized chitosan is 5% to 20%.
9. The core-sheath gradient non-silver antibacterial regenerated cellulose fiber according to claim 6, characterized in that, The average particle size of the quaternized polysilsesquioxane nanoparticles is 60-100 nm; the amount of the quaternized polysilsesquioxane nanoparticles added is 0.50-0.70 parts by mass per 100 parts by mass of shell α-cellulose.
10. The core-sheath gradient non-silver antibacterial regenerated cellulose fiber according to claim 6, characterized in that, The shell thickness accounts for 12% to 14% of the fiber radius.