Sanitary napkin core body based on nanometer material

Abstract

The invention relates to the technical field of hygienic product manufacturing, and discloses a sanitary napkin core body based on a nano material, functional particles are accurately positioned through flow field directional regulation and control of fiber three-dimensional orientation distribution, pulsed electric field activation free radical gradient polymerization and supercritical CO2 deposition, a surface micropore compact water locking layer with the aperture of 5-20 microns is constructed, and an inner macropore flow guide layer is formed. The pore diameter is 80-150 microns, and a cross-scale synergistic structure is formed. Self-reconstruction of the fiber is excited by sudden change of the flow field rotating speed, and mutual exclusion limitation of the absorption rate and the liquid retention amount of a traditional homogeneous structure is broken through in combination with diffusion kinetics of a terahertz wave resonance reinforced cross-linking agent; a C-O-Ag chemical anchoring point is established by a plasma bonding technology, and the nano-silver particles are physically confined by a graphene oxide sheet layer, so that the problems of particle agglomeration and ion burst release in a traditional spraying process are solved. The dynamic multi-field synergistic process realizes porosity gradient, oriented arrangement of molecular chains and long-acting residence of functional particles, and provides a core solution with high absorptivity, zero reverse osmosis and long-acting bacteriostasis for hygienic products.

Description

Technical Field

[0001] The present invention relates to the technical field of hygiene product manufacturing, and specifically to a sanitary napkin core based on nanomaterials. Background Art

[0002] The core performance of absorbent hygiene products (such as sanitary napkins, diapers, etc.) depends on the ability of the core material to quickly absorb and long-term lock in liquids. Traditional materials achieve basic functions through the combination of superabsorbent resin (SAP) and cellulose, but there are mutual constraints among indicators such as absorption rate, liquid retention capacity, and antibacterial properties. With the upgrading of consumers' demands for lightweight and long-term dry and fresh experiences, breaking through the bottleneck of material structure design has become the focus of industry technology research.

[0003] Current technologies mostly use homogenized cross-linked networks to construct porous structures, and regulate the porosity through mechanical foaming or chemical cross-linking. Typical processes include high-temperature thermal-initiated polymerization, nanoparticle surface spraying, etc., relying on a single physical field (such as temperature, pressure) to control the material forming process. Although these methods can achieve basic liquid absorption functions, the structural uniformity leads to the singleization of pore functions.

[0004] Homogeneous structures are difficult to coordinate contradictory performance requirements: large-aperture channels are conducive to rapid absorption but reduce the liquid retention ability; small-aperture water storage improves the liquid locking amount but significantly delays the absorption rate. The distribution of liquid in the core is disordered, leading to local saturation premature aging and aggravated reverse osmosis. How to construct a gradient cross-linked network and break the mutually exclusive relationship between the absorption rate and the liquid locking ability has become the core obstacle restricting the leap of material performance. Summary of the Invention

[0005] Aiming at the deficiencies of the prior art, the present invention provides a sanitary napkin core based on nanomaterials, which solves the problem that the homogeneous cross-linked structure in the prior art cannot coordinate the absorption rate and the liquid locking ability.

[0006] To achieve the above objectives, the present invention is realized through the following technical solutions: A sanitary napkin core based on nanomaterials, comprising a three-dimensional gradient cross-linked network structure and functional nanoparticles uniformly distributed at network nodes; the three-dimensional gradient cross-linked network structure is composed of the following raw materials:

[0007] 3.5 - 5.0 parts of cellulose nanocrystals;

[0008] 0.9 - 1.4 parts of monolayer Ti3C2Tx MXene;

[0009] 13 - 17 parts of acrylic acid-N-vinylpyrrolidone-2-acrylamido-2-methylpropanesulfonic acid copolymer;

[0010] 0.4 - 0.8 parts of tetra-arm polyethylene glycol succinimide ester;

[0011] The functional nanoparticles include:

[0012] 0.025 - 0.045 parts of zinc tetracarboxyphenyl porphyrin;

[0013] 0.18 - 0.32 parts of silver nanoparticles / graphene oxide composite particles;

[0014] Among them, the crosslinking density of the three-dimensional gradient crosslinked network shows an exponential decay distribution from the surface layer to the core layer, and the decay coefficient α = 0.18 - 0.22 mm -1 .

[0015] Preferably, the diameter of the cellulose nanocrystals is 18 - 22 nm, and the aspect ratio ≥ 55; the lateral size of the single-layer Ti3C2Tx MXene is 2.5 - 8.5 μm, and the number of layers ≤ 3 layers.

[0016] Preferably, the functional nanoparticles are fixed at the crosslinked network nodes by supercritical CO2 fluid-assisted deposition technology, and the deposition positioning accuracy ≤ ±1.5 μm, and the coverage rate is 92 ± 3%.

[0017] Preferably, the silver loading in the silver nanoparticles / graphene oxide composite particles is 9 - 11 wt%, and the thickness of the graphene oxide sheet layer ≤ 1.0 nm.

[0018] A preparation method of a sanitary napkin core body based on nanomaterials includes the following steps:

[0019] (1) Nanofiber network construction: Dispersions of cellulose nanocrystals and single-layer Ti3C2Tx MXene are aligned in a Taylor-Couette flow field to form a three-dimensional fiber network skeleton;

[0020] (2) Polymer matrix molding: In-situ free radical polymerization of an acrylic copolymer is carried out in the oriented fiber network to form a polymer matrix with reactive activity;

[0021] (3) Gradient crosslinking and curing: Tetra-arm polyethylene glycol succinimide ester reacts with the polymer matrix through the action of a composite electromagnetic field to form a three-dimensional network structure with a decreasing crosslinking density from the surface layer to the core layer;

[0022] (4) Functional particle loading: Zinc tetracarboxyphenyl porphyrin and silver nanoparticles / graphene oxide composite particles are accurately deposited at the crosslinked network nodes by supercritical fluid technology;

[0023] (5) Interface strengthening treatment: The interfacial bonding strength between the nanoparticles and the polymer network is enhanced by plasma bonding;

[0024] Among them, steps (1) - (5) together constitute a complete core body forming process chain.

[0025] Preferably, in the above (1), the Reynolds number Re of the Taylor-Couette flow field is controlled to be 2500 - 3500, the rotational speed of the inner cylinder is 1450 - 1550 rpm, the rotational speed of the outer cylinder is 630 - 670 rpm, and an axial pressure pulsation with a frequency of 8 - 12 Hz is applied synchronously.

[0026] Preferably, in the above (2), a pulsed electric field is used to initiate the polymerization reaction, the electric field strength is 2.8 - 3.5 kV / cm, the pulse duty cycle is 65 - 75%, and the reaction time is 45 - 75 s.

[0027] Preferably, in the above (3), the following are applied simultaneously:

[0028] Microwave field: power density 3.3 - 3.7 W / cm 3 ;

[0029] Terahertz wave: frequency 0.34 - 0.36 THz;

[0030] Static magnetic field: intensity 1.4 - 1.6 T, and the direction forms an angle of 55 ± 3° with the material flow direction.

[0031] Preferably, the parameters of supercritical CO2 deposition in the above (4) include:

[0032] Pressure 12.8 - 13.5 MPa;

[0033] Temperature 42 - 48 °C;

[0034] Nozzle Mach number Ma = 3.05 - 3.15;

[0035] Deposition positioning accuracy ≤ ±1.5 μm.

[0036] Preferably, the plasma treatment parameters in the above (5) include:

[0037] Power density 1.45 - 1.55 W / cm 2 ;

[0038] Pulse frequency 4.8 - 5.2 kHz;

[0039] Ambient oxygen content 85 - 110 ppm;

[0040] Interface binding energy after treatment ≥ 320 kJ / mol.

[0041] The present invention provides a sanitary napkin core body based on nanomaterials, having the following beneficial effects:

[0042] 1. The present invention adopts a flow field orientation - electric field polymerization multi - stage coupling technology to achieve a gradient distribution of the pores in the core body. The uniform cross - linked structure of the traditional process leads to liquid retention and back - leakage. The present invention forms a cross - scale channel with a dense surface layer and a loose inner layer, breaking through the mutually exclusive bottleneck of the absorption rate and water - locking ability.

[0043] 2. The low-temperature pulsed electric field of the present invention synergistically resonates with terahertz waves to directionally activate cross-linking sites. Conventional thermal-initiated polymerization causes molecular chain entanglement and local overheating. The present invention achieves a narrow molecular weight distribution, and the coefficient of variation of the cross-linking agent distribution is reduced to less than 10%.

[0044] 3. The sudden change in the flow field rotation speed of the present invention is coupled with an electromagnetic field to trigger fiber self-assembly and reconstruction. Static process parameters for curing lead to a decline in mechanical properties. The present invention increases the compressive strength of the core by 2.1 times, and the rebound rate after a thousand compressions still exceeds 85%.

[0045] 4. The supercritical deposition of the present invention combines plasma bonding to lock nano-active sites. Traditional physical mixing causes particle aggregation and burst release. The present invention achieves a positioning accuracy of more than 90% for silver particles, and the antibacterial aging time is extended to 3.6 times that of the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a schematic flow chart of the method of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0047] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0048] Example 1:

[0049] Please refer to the attached Figure 1 , the embodiment of the present invention provides a sanitary napkin core based on nanomaterials, including:

[0050] Component composition:

[0051] Cellulose nanocrystals: 4.2%

[0052] Single-layer Ti3C2T x MXene: 1.1%

[0053] Ternary acrylic copolymer: 15.3%

[0054] Four-armed polyethylene glycol cross-linking agent: 0.6%

[0055] Zinc porphyrin photosensitizer: 0.035%

[0056] Nano-silver / graphene oxide composite: 0.25%

[0057] Deionized water: 78.515%

[0058] Steps and Parameters:

[0059] Fiber Skeleton Molding: Pre - cool deionized water to 5°C. Add cellulose nanocrystals. Adjust the stirring speed to 1800 rpm. Continue for 15 minutes. Add MXene powder. Treat with an ultrasonic crusher. Set the power to 500 W and the frequency to 28 kHz. Treat for 30 minutes.

[0060] Flow Field Orientation: Introduce the mixed solution into a coaxial cylinder reactor. Lock the inner cylinder rotation speed at 1480 rpm and the outer cylinder at 660 rpm. The axial pressure pulsation frequency is 11 Hz. The temperature decreases from 34°C at the inlet to 23°C at the outlet in a gradient. The running time is 48 minutes.

[0061] Electric Field Polymerization: Inject acrylic monomer solution. Adjust the electric field strength to 3.1 kV / cm. The pulse duty cycle is 68%. Set the single - pulse width to 55 μs. Control the electrolyte conductivity at 475 μS / cm. The polymerization reaction lasts for 62 seconds.

[0062] Multi - field Cross - linking: The microwave radiation power density is 3.4 W / cm 3 ². The terahertz emitter frequency is 0.348 THz. The static magnetic field strength is 1.48 T. The angle between the magnetic field direction and the material flow is 56°. The treatment duration is 22 seconds.

[0063] Particle Deposition: Raise the supercritical CO₂ pressure to 13.1 MPa. The nozzle throat diameter is 0.31 mm. The Mach number is stabilized at 3.08. The nanoparticle deposition coverage rate is 93.2%. The positioning error is ±1.3 μm.

[0064] Interface Strengthening: Pump the plasma treatment chamber to a vacuum of 10 Pa. Adjust the oxygen content to 98 ppm. The pulse frequency is 4.9 kHz. The power density is 1.49 W / cm 2 ². The exposure time is 88 seconds.

[0065] The surface cross - linking degree reaches 86.7%. The liquid absorption rate is 12.1 mL / s. The antibacterial rate against Staphylococcus aureus is 99.96%. The core body resilience rate is 92.4%.

[0066] Example 2:

[0067] Component Composition:

[0068] Cellulose Nanocrystals: 3.8%

[0069] Single - layer Ti₃C₂T x MXene: 0.95%;

[0070] Ternary Acrylic Copolymer: 14.2%;

[0071] Four - armed Polyethylene Glycol Cross - linker: 0.45%;

[0072] Zinc porphyrin photosensitizer: 0.028%;

[0073] Silver nanowire / graphene oxide composite: 0.19%;

[0074] pH buffer: 80.387%;

[0075] Steps and parameters:

[0076] Acidic pretreatment: Adjust the pH buffer to 4.3. Add MXene powder. Set the magnetic stirrer speed to 2200 rpm. Maintain a constant temperature of 40 °C. Disperse for 25 minutes.

[0077] Vortex shear: Start the Taylor vortex generator. Suddenly reduce the outer cylinder temperature to 18 °C. Suddenly increase the inner cylinder speed to 1520 rpm. Axial pressure pulsation amplitude 13 kPa. Shear rate γ = 1350 s -1 . Treatment cycle 51 minutes.

[0078] Low-temperature polymerization: Reduce the reactor temperature to 8 °C. Increase the electric field strength to 3.4 kV / cm. Shorten the pulse width to 52 μs. Adjust the duty cycle to 73%. Compress the polymerization time to 49 seconds.

[0079] Electromagnetic coupling: Switch the terahertz wave frequency to 0.357 THz. Reduce the microwave power density to 3.3 W / cm 3 . Increase the magnetic field strength to 1.57 T. Adjust the angle to 54°. Irradiation time 19 seconds.

[0080] Fixed-point deposition: Control the supercritical CO2 pressure fluctuation within ±0.15 MPa. Fine-tune the nozzle throat diameter to 0.29 mm. Suddenly increase the temperature during the deposition stage by 3 °C. Increase the coverage rate to 94.1%.

[0081] Post-treatment: Fill the plasma treatment chamber with nitrogen to atmospheric pressure. Suddenly reduce the oxygen content to 82 ppm. Increase the pulse frequency to 5.1 kHz. Break through the power density of 1.53 W / cm 2 . Treatment duration 94 seconds.

[0082] The core layer porosity is expanded to 68.9%. The liquid diffusion rate is increased by 15%. The E. coli killing rate is 99.93%. The core body compressive strength is increased to 8.7 MPa.

[0083] Example 3:

[0084] Component composition:

[0085] Cellulose nanocrystals: 4.7%;

[0086] Single-layer Ti3C2T x MXene: 1.32%;

[0087] Ternary acrylic copolymer: 16.1%;

[0088] Four-armed polyethylene glycol crosslinker: 0.73%;

[0089] Zinc porphyrin photosensitizer: 0.041%;

[0090] Nano silver / graphene oxide composite: 0.29%;

[0091] Ethanol aqueous solution: 76.818%;

[0092] Steps and parameters:

[0093] Solvent replacement: Adjust the ethanol concentration to 22 vol%. Add cellulose nanocrystals. Adjust the speed of the mechanical stirrer to 1950 rpm. Maintain a constant temperature of 32 °C. Dispersion time is 37 minutes.

[0094] Dynamic flow field: The rotation speed of the outer cylinder changes suddenly three times: 620 → 655 → 680 rpm. The axial pressure pulsation frequency randomly switches between 9 - 13 Hz. Adjust the temperature gradient rate to 1.1 °C / cm. Processing time is 44 minutes.

[0095] Oscillatory polymerization: The electric field strength changes stepwise: 2.9 → 3.3 → 3.6 kV / cm. The pulse duty cycle fluctuates according to 67% → 71% → 75%. The electrolyte conductivity oscillates between 465 - 485 μS / cm. The total reaction time is 67 seconds.

[0096] Energy field modulation: The sudden peak value of the microwave power density is 3.8 W / cm 3 . The terahertz wave frequency jumps to 0.352 THz. The magnetic field direction suddenly reverses by 32°. The processing window is shortened to 17 seconds.

[0097] Deposition enhancement: The nozzle expansion rate is increased to 165 m / s. The Mach number breaks through 3.12. The CO2 pressure oscillates between 13.3 ± 0.3 MPa. The deposition positioning accuracy breaks through ±1.1 μm.

[0098] Free radical activation: The pressure in the plasma processing chamber suddenly changes to 20 Pa. The oxygen content soars to 108 ppm. The pulse front is shortened to 12 ns. The power density limit value is 1.56 W / cm 2 . The processing time is 81 seconds.

[0099] Crosslinking density attenuation coefficient α = 0.21 mm -1 . The transient absorption amount reaches 14.3 mL. The inhibition rate against Candida albicans is 99.89%. The core body can be repeatedly compressed 1000 times without collapse.

[0100] Comparative example 1:

[0101] Prior art solution: Traditional uniform cross-linked structure + mechanical stirring deposition.

[0102] Preparation process:

[0103] Fiber skeleton forming: Same as step 1 of Example 1, but cancel the temperature gradient control and keep the temperature constant at 25°C.

[0104] Flow field orientation: The rotation speeds of both the inner and outer cylinders are set to 1000 rpm (no speed difference), and no axial pressure pulsation is applied.

[0105] Electric field polymerization: DC electric field of 1.5 kV / cm (no pulse modulation), and the polymerization time is extended to 120 s.

[0106] Cross-linking and curing: Only use the microwave field (3.0 W / cm 3 ), cancel the terahertz wave and static magnetic field.

[0107] Particle deposition: Change to the ordinary impregnation method (atmospheric pressure, 40°C aqueous solution, stirring deposition for 30 min).

[0108] Interface treatment: Omit the plasma process and dry with hot air at 80°C for 20 min.

[0109] Key points for comparison: Destroy the gradient cross-linked structure + random distribution of nanoparticles.

[0110] Comparative example 2:

[0111] Prior art solution: High-temperature polymerization + single electromagnetic field cross-linking.

[0112] Preparation process:

[0113] Acidic pretreatment: Same as step 1 of Example 2, but adjust the pH to neutral (7.0).

[0114] ]>Vortex shear: Keep the outer cylinder at a constant temperature of 40°C and cancel the temperature sudden drop.

[0115] Polymerization reaction: Remove the electric field and change to thermal initiation polymerization at 60°C (ammonium persulfate initiator).

[0116] Cross-linking and curing: Only apply a static magnetic field of 1.5 T (cancel the microwave / terahertz wave).

[0117] Particle deposition: Same as step 5 of Example 2, but expand the nozzle throat diameter to 0.50 mm and reduce the Mach number to 2.0.

[0118] Post-treatment: Increase the plasma oxygen content to 200 ppm and the power density to 0.8 W / cm 2 。

[0119] Key points for comparison: Defects of high-temperature initiation polymerization + failure of electromagnetic field synergy.

[0120] Comparative Example 3:

[0121] Existing technical solution: Static flow field + Conventional energy input.

[0122] Preparation process:

[0123] Solvent replacement: Increase the ethanol concentration to 50 vol%, cancel the constant temperature control.

[0124] Flow field treatment: The fixed rotation speed of the outer cylinder is 500 rpm (no dynamic mutation).

[0125] Polymerization reaction: Remove the electric field, use ultraviolet light to initiate instead (wavelength 365 nm, irradiation for 10 min).

[0126] Energy field modulation: Only use the microwave field (2.4 W / cm 3 ), cancel the terahertz / magnetic field modulation.

[0127] Deposition enhancement: Reduce the CO2 pressure to 8.0 MPa (subcritical state), extend the deposition time to 2 h.

[0128] Interface treatment: Reduce the plasma pulse frequency to 1 kHz, power density 0.5 W / cm 2 .

[0129] Key points for comparison: Disorder of the flow field + Insufficient intensity of the energy field.

[0130] Comparative Example 4:

[0131] Existing technical solution: Non-gradient structure + Non-covalent binding

[0132] Preparation process:

[0133] Fiber network: Cancel the addition of MXene, only use cellulose nanocrystals (the proportion is increased to 6.0%).

[0134] Polymer matrix: Change to linear polyacrylic acid (non-copolymer), replace the cross-linking agent with ethylenediamine (1.2%).

[0135] Crosslinking and curing: Uniform crosslinking in the whole area (no gradient design), the crosslinking degree is uniformly set to 75%.

[0136] Particle loading: Physical mixing of zinc porphyrin and silver nanoparticles (non-composite), directly spray on the surface.

[0137] Interface treatment: Omit the supercritical deposition and plasma processes.

[0138] Key points for comparison: Simplification of components + Lack of interface bonding force.

[0139] Comparative Example 5:

[0140] Existing technical solution: Traditional flow field + single parameter control

[0141] Preparation process:

[0142] Flow field orientation: A plug flow reactor is used (non-Taylor-Couette flow field), and the shear rate is fixed at 500 s -1 .

[0143] Polymerization reaction: The pulse duty cycle is set to 100% (continuous electric field), and the dynamic adjustment of the duty cycle is removed.

[0144] Electromagnetic coupling: Only the microwave field (3.5 W / cm 3 ) is retained, and the cooperation of terahertz and magnetic field is cancelled.

[0145] Deposition control: The nozzle throat diameter is enlarged to 0.45 mm, and the Mach number is stabilized at 2.5.

[0146] Interface treatment: The plasma oxygen content is set to 20 ppm, and the power density is 0.3 W / cm 2 .

[0147] Key points of comparison: Disordered flow field + parameter solidification.

[0148] Experiment 1: Test on the liquid management effect of gradient cross-linked structure

[0149] Experiment description:

[0150] Test objects: Example 1, Comparative Example 1, Comparative Example 4;

[0151] Test parameters: Absorption rate (mL / s), liquid retention amount (mL / g), reverse osmosis amount (g);

[0152] Experiment conditions:

[0153] Artificial menstrual fluid: Sodium carboxymethylcellulose (0.9 wt%) + NaCl (0.6 wt%)

[0154] Temperature: 37 ± 0.5 °C, Humidity: 50 ± 5%

[0155] Sample size: 10 × 10 cm

[0156] Experiment steps:

[0157] Sample pretreatment: All samples are left standing at constant temperature and humidity (37 °C / 50%) for 24 h.

[0158] Absorption rate test: The sample is laid flat on the test bench. The injection pump injects artificial menstrual fluid at a rate of 3 mL / s. Trigger the high-speed camera (1000 fps) to record the rising process of the liquid surface. Calculate the soaking time.

[0159] Liquid Retention Test: Place the saturated absorption sample into a centrifuge tube. Set the centrifuge to 3000 rpm for 5 minutes. Weigh the mass difference before and after centrifugation.

[0160] Reverse osmosis test: Load a 4.8 kPa pressure plate. Place a set amount of filter paper underneath. After 5 minutes, weigh the filter paper weight gain.

[0161] Table 1. Comparison of liquid management performance

[0162] Group Absorption rate (mL / s) Liquid retention amount (mL / g) Reverse osmosis amount (g) Example 1 12.37 44.92 0.071 Comparative Example 1 6.51 28.34 0.413 Comparative Example 4 3.22 16.78 1.205 Example 1-2 11.89 43.15 0.083 Comparative Example 1-3 7.02 25.91 0.388

[0163] The high-density surface region of the gradient cross-linked network (cross-linking degree 86%) forms a rigid framework, generating capillary negative pressure upon liquid contact. The sodium carboxymethyl cellulose solution is drawn into the top channels with pore sizes of 20-50 μm within 0.3 seconds. Example 1 achieved an absorption rate exceeding 12 mL / s, 1.9 times faster than Comparative Example 1.

[0164] The uniform cross-linked structure of Comparative Example 1 resulted in a chaotic pore distribution. Macropores (100-300 μm) were randomly connected to micropores (10 μm). Turbulent vortices appeared at the flow front, increasing energy dissipation. The liquid retention rate plummeted to 28 mL / g, while the reverse osmosis rate soared to over 0.4 g.

[0165] The precise anchoring of nanoparticles at the nodes of Example 1 (coverage rate 93%) reduces the effective pore cross-sectional area. Fluid resistance is reduced. In contrast, the random spraying of Comparative Example 4 causes the graphene oxide sheets to block more than 50% of the pores. The liquid retention capacity is only 16mL / g. The reverse osmosis volume exceeds 1.2g. The data proves that the synergistic effect of gradient structure and targeted deposition is irreplaceable.

[0166] Experiment 2: Verification of low-temperature field-controlled polymerization accuracy

[0167] Experimental description:

[0168] Test objects: Example 2, Comparative Example 2, Comparative Example 5;

[0169] Core parameter: molecular weight distribution index Cross-linker distribution uniformity (CV value), reaction temperature fluctuation (ΔT);

[0170] Testing equipment:

[0171] GPC instrument (Waters 1515);

[0172] Laser confocal microscopy (Zeiss LSM 880);

[0173] Infrared thermal imaging camera (FLIR A655sc);

[0174] Experimental steps:

[0175] Sample preparation: Take the core substrate layer (avoiding the functional particle area), crush it, sieve it through an 80-mesh sieve, dissolve it in DMF (concentration 5 mg / mL), and filter it through a 0.22-μm filter membrane.

[0176] Molecular weight detection: The column temperature of GPC is 35 °C. The flow rate of the mobile phase is 1.0 mL / min. Inject samples three times and take the average value. Calculate the number-average molecular weight (Mn) and the distribution index.

[0177] Crosslinking agent distribution: Immerse the sample in rhodamine B staining solution (0.005 wt%) for 30 min. The laser excitation wavelength is 552 nm. Collect 10 fields of view and calculate the coefficient of variation (CV).

[0178] Temperature monitoring: Align the thermal imager with the reaction area. Collect the highest temperature point every 10 seconds. Calculate the extreme value of the temperature difference during the process (ΔT = Tmax - Tmin).

[0179] Table 2. Comparison of polymerization control performance

[0180]

[0181] The duty cycle modulation of the pulsed electric field controls the peak value of the free radical concentration below 0.12 mol / L. The value of 1.28 in Example 2 shows that the chain growth is highly controllable. After removing the pulse in Comparative Example 2, the explosive polymerization causes Mn to soar from 120,000 to 180,000. The distribution index deteriorates to 1.67. The thermal imager captures a temperature rise of 9.8 °C. Local hot spots trigger pre-crosslinking. The difference in the CV value of the crosslinking agent is more intuitive. The 8.3% uniformity in Example 2 comes from the terahertz wave drive. The 0.35 THz frequency excites the C-N bond resonance. The diffusion rate of the crosslinking agent is increased by 3 times. In Comparative Example 5, only the microwave field is used. The crosslinking agent accumulates at the nodes. The CV value breaks through 27%. Fluorescent clusters are visible in the field of view.

[0182] The temperature fluctuation ΔT = 2.1 °C proves the advantage of low-temperature field control. The thermal initiation in Comparative Example 2 forces the cooling system to start intermittently. The temperature curve shows a sawtooth oscillation. Molecular chain breaks occur in the highest temperature area. The infrared spectrum shows local carbonization points. The data confirm that removing the multi-field cooperation will cause the chain structure to get out of control.

[0183] [[ID=ID=27]]The temperature fluctuation ΔT = 2.1 °C proves the advantage of low-temperature field control. The thermal initiation in Comparative Example 2 forces the cooling system to start intermittently. The temperature curve shows a sawtooth oscillation. Molecular chain breaks occur in the highest temperature area. The infrared spectrum shows local carbonization points. The data confirm that removing the multi-field cooperation will cause the chain structure to get out of control.

[0184] Experiment 3: Evaluation of the structural stability of the dynamic energy field

[0185] Experimental description

[0186] Test objects: Example 3, Comparative Example 3, Comparative Example 5;

[0187] Core parameters: Compressive strength (MPa), rebound rate (%), porosity (%);

[0188] Testing equipment:

[0189] Universal material testing machine (Instron 5967);

[0190] Cyclic compression fixture (ASTM D3574 standard);

[0191] Mercury intrusion porosimeter (Micromeritics AutoPore IV 9500);

[0192] Experimental procedures:

[0193] Sample treatment: The core is made into a cylinder with a diameter of 30 mm. The end faces are polished to Ra ≤ 0.8 μm. Pretreatment is carried out at a constant temperature of 25 °C for 48 h.

[0194] Compressive strength test: The compression rate is 50 mm / min. Record the stress value at 50% deformation. Take the median value of three tests.

[0195] Rebound test: Immediately release after compression at 80% deformation. Measure the thickness recovery rate within 10 s. Calculate the attenuation slope after 100 cycles.

[0196] Pore analysis: The sample is crushed into particles with a size of 1 - 3 mm. The mercury intrusion pressure is 0.1 - 400 MPa. Calculate the proportion of the cumulative pore volume.

[0197] Table 3. Comparison of structural stability

[0198] Group Compressive strength (MPa) Rebound rate (%) Porosity (%) Example 3 9.12 88.7 63.4 Comparative Example 3 4.35 62.1 51.8 Comparative Example 5 5.78 73.5 57.2 Example 3-2 8.97 87.3 65.1 Comparative Example 3-3 3.91 58.9 49.7

[0199] The sudden rotation speed of the dynamic flow field triggers the self - reconstruction of the fiber network. The Taylor vortex frequency jumps from 8 Hz to 13 Hz. The MXene sheets rotate and slip under stress. The compressive strength of Example 3 breaks through 9 MPa. While the static flow field of Comparative Example 3 causes the fiber bundles to stack parallelly. Stress concentration occurs during compression and fractures. The strength drops sharply to 4.35 MPa.

[0200] The difference in the rebound rate is more acute. The gradient cross - linking in Example 3 forms a memory skeleton. After 80% compression, the entropy elasticity of the molecular chains is released. 87% of the thickness is recovered within 10 s. The uniform cross - linking in Comparative Example 5 intensifies the energy dissipation. After 100 cycles, the rebound rate decays to less than 50%. The cross - section electron microscopy shows the expansion of microcracks.

[0201] The mercury intrusion data reveals a deep correlation. Among the 63.4% porosity of Example 3, the pores with a size of 20 - 100 μm account for 71%, forming a continuous buffer layer. Among the 51.8% porosity of Comparative Example 3, the macropores with a size > 200 μm account for 38%, and the stress transfer path breaks. The data proves that the dynamic modulation of the energy field is the core variable for structural stability

[0202] Experiment 4: Correlation analysis of nanoparticle localization and antibacterial property

[0203] Experimental description: Test objects: Examples 1 - 3, Comparative Example 4;

[0204] Core parameters: Uniformity of Ag element distribution (RSD%), Bacteriostatic rate (%), Ag + release amount (μg / cm 2 / h);

[0205] Detection equipment:

[0206] Field emission scanning electron microscope (FE - SEM, Hitachi SU8220);

[0207] Inductively coupled plasma optical emission spectrometer (ICP - OES, PerkinElmer Avio500);

[0208] Microbial incubator (Thermo Scientific Heratherm);

[0209] Experimental procedures:

[0210] Sample treatment: SEM - EDS sample: The surface of the core body is sputter - coated with gold (thickness 5 nm), acceleration voltage 5 kV, working distance 8 mm.

[0211] Bacteriostatic test:

[0212] Bacterial suspension preparation: The concentration of Escherichia coli (ATCC 25922) suspension is adjusted to 1×10 5 CFU / mL.

[0213] Contact culture: The sample is in contact with the bacterial suspension for 24 h (37 °C), and the viable bacteria are counted by the neutral red staining method.

[0214] Ag + Release:

[0215] Artificial sweat immersion: Lactic acid 0.5 wt% + Urea 0.25 wt% + NaCl 0.5 wt%.

[0216] ICP - OES detection: Wavelength 328.068 nm, and the average value of three parallel samples is taken.

[0217] Table 4. Comparison of the efficacy of nanoparticles

[0218]

[0219] The positioning accuracy of supercritical CO2 deposition (±1.5 μm) confined the silver nanoparticles to the crosslinking nodes. EDS surface scanning showed that the relative standard deviation (RSD) of the Ag element in Example 1 was only 12.3%. The silver cluster size was ≤50 nm. In contrast, the physical mixing in Comparative Example 4 resulted in silver particle agglomeration (>200 nm). The RSD soared to 68.5%. The antibacterial rate plummeted to 82%.

[0220] The plasma treated CO-Ag bond suppresses the release of silver ions. + Release amount 0.153μg / cm 2 / h, which is 5.8 times lower than that of comparative example 4. The sustained release curve fitting showed a first-order kinetic model (R 2 =0.993). The free silver of Comparative Example 4 released a peak value of 1.2 μg / cm within 2 hours. 2 . The risk of cytotoxicity increases.

[0221] The π-π stacking of graphene oxide strengthens the fixation of silver particles. The 99.91% antibacterial rate of Example 3 is derived from the synergistic effect. SEM shows that the GO sheets wrap the silver particles (coverage > 90%). The lack of GO in Comparative Example 4 leads to oxidation of silver particles. XPS detected that Ag2O accounts for 38%. More than half of the active silver is lost. Data proves that precise positioning and interface bonding are the core conditions for long-term antibacterial effect

[0222] Experiment 5: Evaluation of the impact of process chain collaboration on production efficiency

[0223] Experimental description:

[0224] Test objects: Examples 1-3, Comparative Example 5;

[0225] Core parameters: production cycle (min / batch), energy consumption index (kW·h / kg), yield rate (%);

[0226] Monitoring equipment:

[0227] Production line full process monitoring system (Siemens S7-1500 PLC);

[0228] High-precision power meter (Yokogawa WT500);

[0229] Industrial X-ray flaw detector (Comet Yxlon FF35);

[0230] Experimental steps:

[0231] Production cycle recording: Video recording of the entire process from raw material feeding to finished product packaging. Timestamp accuracy to 0.1 second. Abnormal periods such as equipment failure are eliminated.

[0232] Energy consumption acquisition: The power meter is connected to the main circuits of the three sections of flow field orientation, aggregation, and deposition. The real-time current clamp records the effective power. The unit mass energy consumption is converted.

[0233] Good product rate detection: The sample is scanned by X-ray (voltage 90 kV, current 150 μA). The AI image analysis system (Halcon 21.05) identifies internal defects.

[0234] Table 5. Process efficiency comparison

[0235]

[0236] The dynamic parameter adjustment compresses the flow field orientation time by 38%. The PLC data stream of Example 2 shows that the inner cylinder rotation speed is intelligently adjusted in the range of 1480 - 1520 rpm. The Re number fluctuation is controlled within ±150. Compared with the fixed rotation speed scheme of Comparative Ratio 5, the energy consumption drops by 51%.

[0237] The multi-field coupling triggers the self-optimization of the process chain. The microwave-terahertz cooperation shortens the crosslinking and curing time to 22 seconds. The single energy input of Comparative Ratio 5 forces the deposition section to wait for 9 minutes. The X-ray pattern shows that the core void defect rate of the traditional process is as high as 17.9%.

[0238] The real-time data interaction breaks the process barriers. The OPC UA protocol realizes the linkage of flow field parameters → electric field strength → nozzle Mach number. The good product rate of 98.4% in Example 1 stems from this closed-loop control. The independent sections of Comparative Ratio 5 cause parameter conflicts. The power meter captures a 214% sudden increase in current during the deposition stage. The thermal imaging shows local overload ablation. The data confirms that the process chain cooperation is a necessary condition for industrial implementation.

[0239] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A sanitary napkin core based on nanomaterials, characterized in that, It includes a three-dimensional gradient crosslinked network structure and functional nanoparticles uniformly distributed at the network nodes; The three-dimensional gradient crosslinked network structure is composed of the following raw materials: 3.5 - 5.0 parts of cellulose nanocrystals; 0.9 - 1.4 parts of monolayer Ti3C2Tx MXene; 13 - 17 parts of acrylic acid-N-vinylpyrrolidone-2-acrylamido-2-methylpropanesulfonic acid copolymer; 0.4 - 0.8 parts of tetra-arm polyethylene glycol succinimidyl ester; The functional nanoparticles include: 0.025 - 0.045 parts of zinc tetracarboxyphenyl porphyrin; 0.18 - 0.32 parts of silver nanoparticles / graphene oxide composite particles; Among them, the crosslinking density of the three-dimensional gradient crosslinked network shows an exponential decay distribution from the surface layer to the core layer, and the decay coefficient α = 0.18 - 0.22 mm -1 .

2. The sanitary napkin core based on nanomaterials according to claim 1, wherein, The diameter of the cellulose nanocrystals is 18 - 22 nm, and the aspect ratio is ≥55; the lateral size of the monolayer Ti3C2Tx MXene is 2.5 - 8.5 μm, and the number of layers is ≤3 layers.

3. The sanitary napkin core based on nanomaterials according to claim 1, characterized in that, The functional nanoparticles are fixed at the crosslinked network nodes by supercritical CO2 fluid-assisted deposition technology, with a deposition positioning accuracy of ≤±1.5 μm and a coverage rate of 92±3%.

4. The sanitary napkin core based on nanomaterials according to claim 1, characterized in that, In the silver nanoparticles / graphene oxide composite particles, the silver loading is 9 - 11 wt%, and the thickness of the graphene oxide sheet layer is ≤1.0 nm.

5. A method for preparing a sanitary napkin core based on nanomaterials, according to any one of claims 1-4, a sanitary napkin core based on nanomaterials, characterized in that, It includes the following steps: (1) Nanofiber network construction: Dispersions of cellulose nanocrystals and monolayer Ti3C2Tx MXene are oriented and arranged in a Taylor-Couette flow field to form a three-dimensional fiber network skeleton; (2) Polymer matrix forming: In-situ radical polymerization of an acrylic copolymer is carried out in the oriented fiber network to form a polymer matrix with reactive activity; (3) Gradient crosslinking and curing: Through the action of a composite electromagnetic field, tetra-arm polyethylene glycol succinimidyl ester reacts with the polymer matrix to form a three-dimensional network structure with a decreasing crosslinking density from the surface layer to the core layer; (4) Functional particle loading: Zinc tetracarboxyphenyl porphyrin and silver nanoparticles / graphene oxide composite particles are accurately deposited at the crosslinked network nodes by supercritical fluid technology; (5) Interface strengthening treatment: The interfacial bonding strength between the nanoparticles and the polymer network is enhanced by plasma bonding; Among them, steps (1)-(5) together constitute a complete core forming process chain.

6. A method for preparing a sanitary napkin core body based on nanomaterials according to claim 5, characterized in that In (1), the Reynolds number Re of the Taylor-Couette flow field is controlled to be 2500 - 3500, the rotational speed of the inner cylinder is 1450 - 1550 rpm, the rotational speed of the outer cylinder is 630 - 670 rpm, and an axial pressure pulsation with a frequency of 8 - 12 Hz is applied synchronously.

7. A method for preparing a sanitary napkin core based on nanomaterials according to claim 5, characterized in that, In (2), a pulsed electric field is used to initiate the polymerization reaction, with an electric field strength of 2.8 - 3.5 kV / cm, a pulse duty cycle of 65 - 75%, and a reaction time of 45 - 75 s.

8. A method for preparing a sanitary napkin core body based on nanomaterials according to claim 5, characterized in that In (3), the following are applied simultaneously: Microwave field: power density 3.3 - 3.7 W / cm 3 ; Terahertz wave: frequency 0.34 - 0.36 THz; Static magnetic field: intensity 1.4 - 1.6 T, and the direction forms an angle of 55±3° with the material flow direction.

9. A method for preparing a sanitary napkin core based on nanomaterials according to claim 5, characterized in that, The parameters of supercritical CO2 deposition in (4) include: Pressure 12.8 - 13.5 MPa; Temperature 42 - 48 °C; Nozzle Mach number Ma = 3.05 - 3.15; Deposition positioning accuracy ≤±1.5 μm.

10. A method for preparing a sanitary napkin core body based on nanomaterials according to claim 5, characterized in that, The plasma treatment parameters in (5) include: Power density 1.45 - 1.55 W / cm 2 ; Pulse frequency 4.8 - 5.2 kHz; The environmental oxygen content is 85 - 110 ppm; The interfacial binding energy after treatment is ≥ 320 kJ / mol.

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