Absorption core body composite structure, preparation method and application

Abstract

The invention discloses an absorption core body composite structure, a preparation method and application. The foaming material layer is located on the upper layer and is subjected to hydrophilic long-acting modification, the wood pulp composite layer is located on the middle layer, and the functional viscose layer is located on the lower layer. The upper layer, the middle layer and the lower layer are compounded through a sectional spunlace process and low-temperature activation treatment. According to the invention, sectional spunlace and low-temperature activation treatment are adopted, so that the interlayer binding force is enhanced. The structure is high in liquid permeation efficiency, long-acting and stable in hydrophilicity, resistant to gel blockage, stable in structure, outstanding in antibacterial property, wide in application scene, good in compatibility with an existing production line and convenient to industrially popularize.

Description

Technical Field

[0001] This invention relates to the field of absorbent materials technology, specifically to an absorbent core composite structure, preparation method, and application, which can be widely used in hygiene products (such as diapers, sanitary napkins, and nursing pads), medical care products, and industrial absorbent materials. Background Technology

[0002] As a core component in hygiene products, medical care materials, and industrial absorbent materials, the performance of the absorbent core directly affects the user experience and functional reliability of the product. Traditional absorbent cores generally suffer from the following problems: Structural uniformity and performance imbalance: Early absorbent cores mostly adopted a simple hybrid structure of "wood pulp + superabsorbent polymer (SAP)". Although it can achieve basic liquid absorption function, it has defects such as poor air permeability (air permeability is usually <3000mL / (cm²・s)) and antibacterial effect depends on chemical coating (such as nano silver) and is easy to leave residues. For example, the traditional "sandwich" structure core is prone to delamination and clumping under liquid impact or external force due to weak interlayer bonding, resulting in a significant increase in reabsorption (>5g).

[0003] The conflict between functionality and biocompatibility: Hygiene products and medical applications demand extremely high biocompatibility from absorbent cores (cell viability >80%), but traditional antibacterial agents (such as quaternary ammonium salts) can easily cause skin irritation or cytotoxicity. Furthermore, absorbent materials need to balance liquid absorption capacity (typically <10 times) and pressure resistance; traditional structures, after absorbing high-viscosity liquids, exhibit a thickness recovery rate of less than 70%, making them unsuitable for long-term use. While traditional foamed sponges are used in filter materials, their hydrophilic modification largely relies on surface coatings, resulting in the defect of easily detached hydrophilic layers, and their open-cell ratio is generally below 85%, failing to meet the requirements for high-speed liquid conduction.

[0004] Process limitations: Traditional hydroentangling processes achieve fiber entanglement through a single high-pressure impact, which easily leads to uneven interlayer bonding strength (peel strength <0.5N / 25mm) and makes it difficult to form a regular porous structure. At the same time, high-temperature treatment (>80℃) will damage the water absorption properties of SAP particles, limiting the synergistic application of functional materials. Summary of the Invention

[0005] To address the aforementioned shortcomings, this invention proposes an absorbent core composite structure, its preparation method, and its application. Through material innovation, structural optimization, and process improvement, it achieves a comprehensive enhancement in absorption performance, stability, and practicality.

[0006] To achieve the above objectives, the absorbent core composite structure of the present invention comprises an upper layer of hydrophilic long-lasting modified foam material, a middle layer of wood pulp composite material, and a lower layer of functional adhesive material; the upper, middle, and lower layers are composited by a segmented hydroentangling process and a low-temperature activation treatment.

[0007] Furthermore, the upper foaming material is selected from at least one of polyurethane, polyethylene, polypropylene, polyester, polyether, silicone rubber, or rubber-based foaming materials; the hydrophilic long-lasting modification is performed using at least one of the following methods: (a) During the foaming stage, 5%-8% of acrylic monomers by weight of the matrix are introduced. After molding, the grafting of polyvinylpyrrolidone is initiated by irradiation with 365nm ultraviolet light for 5-10 minutes. (b) The surface is treated with plasma to form oxygen-containing polar groups. The treatment conditions are 200-500W power and 1-5 minutes time, and the gas is oxygen or air. (c) Disperse and add 3%-5% by mass of hydrophilic nano silica particles with a particle size of 10-50nm and a specific surface area of ​​100-300m² / g; (d) Use block copolymers containing polyethylene glycol segments as foaming aids. The polyethylene glycol segments have a molecular weight of 1000-5000 and the amount added is 2%-4% of the matrix mass.

[0008] Furthermore, the contact angle of the upper foam material is still <40 degrees after 5 water washes; the pore size is gradient distributed along the thickness direction, with a pore size of 0.1-0.3 mm on the upper surface and 0.8-1 mm at the lower interface (the bonding surface between the upper and middle layers); the open porosity is >90%, the density is 0.03-0.08 g / cm³, and the compression resilience is ≥85%.

[0009] Furthermore, the intermediate layer is a mixture of wood pulp fiber and bamboo pulp fiber at a mass ratio of 7:3, wherein the bamboo pulp fiber has a length of 0.5-2 mm and a hollow structure cavity diameter of 5-10 μm; the intermediate layer is also coated with superabsorbent polymer particles on the surface of the wood pulp fiber by a 2% sodium carboxymethyl cellulose solution, wherein the superabsorbent polymer particles have a particle size of 300-500 μm and the amount added is ≤20% of the mass of the intermediate layer.

[0010] Furthermore, the viscose fiber spinning solution of the lower functional viscose layer contains nano-zinc oxide modified with an amphiphilic silane coupling agent, with an addition amount of 0.3%-0.5%; 0.5%-1% of a soluble porogen (such as polyethylene glycol or sucrose) is added to the spinning solution simultaneously; the viscose fiber contains 5%-8% polycaprolactone, which forms a dynamic hydrogen bond network with the nano-zinc oxide.

[0011] Furthermore, the segmented hydroentangling process includes: a pre-piercing pressure of 5-8 MPa, a main piercing pressure of 15-20 MPa, and a shaping piercing pressure of 8-10 MPa; and the formation of a diamond pattern with a depth of 0.5 mm and a spacing of 5 mm on the core surface using a patterned roller.

[0012] Furthermore, the low-temperature activation treatment is performed by microwave activation at 40-50℃ after hydroentangling, with a power of 300W and a time of 2 minutes, resulting in an interlayer peel strength ≥0.8N / 25mm.

[0013] To achieve the above objectives, the method for preparing the absorber core composite structure of the present invention includes: (1) Prepare an upper foam material layer and modify the foam material to be hydrophilic by at least one modification method; (a) During the foaming stage, 5%-8% of acrylic monomers by weight of the matrix are introduced. After molding, the grafting of polyvinylpyrrolidone is initiated by irradiation with 365nm ultraviolet light for 5-10 minutes. (b) The surface is treated with plasma to form oxygen-containing polar groups. The treatment conditions are 200-500W power and 1-5 minutes time, and the gas is oxygen or air. (c) Disperse and add 3%-5% by mass of hydrophilic nano silica particles with a particle size of 10-50nm and a specific surface area of ​​100-300m² / g; (d) Block copolymers containing polyethylene glycol segments are used as foaming agents. The molecular weight of the polyethylene glycol segments is 1000-5000, and the addition amount is 2%-4% of the matrix mass. (2) Preparation of intermediate wood pulp composite layer: wood pulp fiber and bamboo pulp fiber are mixed at a mass ratio of 7:3, and SAP particles with a particle size of 300-500μm are coated on the surface of the mixed fibers with a 2% CMC solution; (3) Preparation of the lower functional viscose layer: Add 0.3%-0.5% nano zinc oxide and 5%-8% PCL to the viscose fiber spinning solution; (4) Stack the above three layers of materials in sequence and composite them using a segmented hydroentanglement process: pre-punching pressure 5-8MPa, main punching pressure 15-20MPa, shaping punching pressure 8-10MPa, and use patterned rollers to form diamond patterns with a depth of 0.5mm and a spacing of 5mm. (5) After hydroentangling, the core is activated by microwave at 300W power for 2 minutes at 40-50℃ to obtain the absorber core composite structure.

[0014] To achieve the above objectives, the absorbent core composite structure of the present invention is applied to hygiene products, medical care products, or industrial absorbent materials; the hygiene products include diapers, sanitary napkins, nursing pads, adult incontinence products, or medical dressings. The hygiene products include a surface layer and an absorbent core layer, wherein the surface layer is made of insulating and soothing nonwoven fabric; and the absorbent core layer employs the aforementioned absorbent core composite structure. Compared with the prior art, the present invention has the following advantages: High liquid permeation efficiency: The gradient pore size design and high hydrophilicity of the upper foam material increase the liquid conduction speed by 15%-20% compared with a uniform pore size structure, solving the problem of high liquid permeation resistance.

[0015] Long-lasting and stable hydrophilicity: Through the synergistic effect of multiple modification methods, the hydrophilic life of the upper foam material is extended to the entire product life cycle (≥3 years), overcoming the defect of easy detachment of traditional hydrophilic layers.

[0016] Excellent anti-gel blockage performance: The "fiber-SAP" core-shell structure of the middle layer avoids gel blockage caused by SAP agglomeration, increases the liquid absorption rate by 40% compared with the direct mixing method, and breaks through the traditional SAP addition limit.

[0017] Strong structural stability: The combination of segmented hydroentangling process and low-temperature activation treatment increases the interlayer peel strength by 60% compared with the traditional hydroentangling process. At the same time, the shape memory characteristics of the lower adhesive layer improve the core's resistance to deformation by 50%.

[0018] Outstanding antibacterial properties: The sustained release of nano zinc oxide in the lower adhesive layer achieves continuous antibacterial effect, solving the problem of easy bacterial growth in traditional cores and meeting medical-grade hygiene requirements.

[0019] It has a wide range of applications: it meets the needs of hygiene products and industrial leakage absorption.

[0020] Good production compatibility: It is compatible with existing hygiene product production lines, requires no large-scale equipment modification, and is easy to promote industrially. Attached Figure Description

[0021] Figure 1 This is a flowchart of the segmented hydroentangling process in this invention. Figure 2 This is a schematic diagram of the low-temperature activation process in this invention. Detailed Implementation

[0022] The present invention will now be described in detail with reference to the embodiments.

[0023] The absorber core composite structure of the present invention is composed of an upper layer, a middle layer, and a lower layer, which are composited through a segmented hydroentangling process and a low-temperature activation treatment. The materials and characteristics of each layer are as follows:

[0024] The upper foaming material is selected from at least one of polyurethane, polyethylene, polypropylene, polyester, polyether, silicone rubber, or rubber-based foaming materials, and hydrophilicity long-lasting modification is achieved by at least one of the following modification methods: (a) Introduce acrylic monomers accounting for 5%-8% of the matrix mass during the foaming stage. After molding, graft polyvinylpyrrolidone (PVP) by ultraviolet light initiation. The ultraviolet light wavelength is 365nm, the power is 100W, and the irradiation time is 5-10 minutes. (b) Forming oxygen-containing polar groups on the surface of the foamed material by plasma treatment, with treatment conditions of 200-500W power and 1-5 minutes, and the gas being oxygen or air; Plasma treatment enhances the hydrophilicity of foamed materials through the following methods: Introducing polar groups: Oxygen or air plasma contains a large number of active particles (such as oxygen radicals O・, ozone O3, etc.). At a power of 200-500W, these high-energy particles bombard the surface of the foamed material, breaking the original hydrophobic C-C and CH chemical bonds on the surface and combining with surface molecules to form oxygen-containing polar groups such as hydroxyl (-OH), carboxyl (-COOH), and carbonyl (-C=O). These polar groups can form hydrogen bonds with water molecules, significantly increasing the material's affinity for water. Surface micromorphology optimization: The etching effect of plasma creates micro-uneven structures (micron-level roughening) on ​​the material surface, increasing the surface contact area. Combined with the effect of polar groups, this further reduces the contact angle of the liquid on the surface, promoting water spreading and penetration.

[0025] (c) Disperse 3%-5% by mass of hydrophilic nano silica particles in the foaming material, with a particle size of 10-50nm and a specific surface area of ​​100-300m² / g. (d) A block copolymer containing polyethylene glycol segments is used as a foaming agent, wherein the molecular weight of the polyethylene glycol segments is 1000-5000, and the amount added is 2%-4% of the mass of the foaming material matrix.

[0026] After modification, the contact angle of the foamed material remains <40 degrees after 5 washes. Its pore size exhibits a gradient distribution along the thickness direction, with pores of 0.1-0.3 mm on the upper surface and 0.8-1 mm at the interface of the lower layer (the junction between the upper and middle layers), resulting in an open porosity >90%. The density is 0.03-0.08 g / cm³, and the compression resilience is ≥85%. The relatively dense structure of the small-pore area in the upper layer provides mechanical support, preventing excessive deformation of the foamed material under pressure (such as during wear) and maintaining the integrity of the surface liquid channels. The large-pore area in the lower layer, combined with the overall open porosity of >90%, provides ample space for gas flow. Combined with the high breathability of the functional adhesive layer (≥5000 mL / (cm²・s)), this effectively reduces stuffiness and improves user comfort (especially suitable for long-term wear of hygiene products). For low-flow liquids (such as daily secretions), the capillary force of the small pores in the upper layer can quickly absorb and guide the liquid to the middle layer; for high-flow sudden liquids (such as urine impact from baby diapers), the rapid spread of the upper layer can disperse the liquid pressure, while the large pores in the lower layer can quickly channel a large amount of liquid, avoiding side leakage caused by instantaneous liquid accumulation. At the same time, combined with the high absorbency (15-30 times) of the SAP particles in the middle layer, a synergistic effect of "rapid liquid conduction - efficient water retention" is achieved.

[0027] In summary, this gradient aperture design achieves full-process optimization of "rapid surface response - efficient conduction in the middle layer - full absorption in the core" by precisely matching the needs of the liquid at different stages of transport. It is a key structural innovation to improve the overall performance of the absorber core.

[0028] Fiber ratio: Mix wood pulp fiber and bamboo pulp fiber at a mass ratio of 7:3 (bamboo pulp fiber length 0.5-2mm, hollow structure cavity diameter 5-10μm).

[0029] SAP particle coating: Contains superabsorbent polymer (SAP) particles (particle size 300-500μm, addition amount ≤20%) uniformly coated on the surface of wood pulp fibers by a 1%-2% sodium carboxymethyl cellulose (CMC) solution.

[0030] Basic parameters: weight 40-80g / m², thickness 1.5-3.0mm.

[0031] SAP particles are coated onto the surface of wood pulp fibers using a sodium carboxymethyl cellulose (CMC) solution. The CMC acts as a "bonding medium," ensuring uniform adhesion and fixation of the SAP particles to the wood pulp fiber surface, forming a core-shell structure of "wood pulp fiber-CMC-SAP." Specifically, SAP particles are dispersed in a 1%-2% CMC solution. The CMC solution, through its viscosity, encapsulates and adheres the SAP particles to the wood pulp fiber surface. After drying, the CMC forms a thin protective film, preventing SAP particle aggregation and promoting rapid liquid penetration into the SAP particles, thus improving water absorption efficiency. Therefore, CMC does not individually coat the wood pulp fibers or SAP particles; rather, it achieves uniform coating of SAP particles on the wood pulp fiber surface through a solution system. The core purpose is to optimize the bonding state between SAP and wood pulp fibers, preventing "gel blockage."

[0032] The intermediate layer is a 7:3 blend of bamboo pulp fiber and wood pulp fiber. The core principle is to leverage the unique structure and performance advantages of bamboo pulp fiber to create a complementary function with wood pulp fiber, further optimizing liquid conduction and structural support within the absorbent core. ① Compared to solid wood pulp fiber, hollow bamboo pulp fiber increases liquid diffusion speed by 20%-30%. Combined with the high hygroscopicity of wood pulp fiber, this creates a synergistic effect of "rapid conduction + full absorption," resulting in a higher overall liquid absorption rate for the intermediate layer compared to a pure wood pulp structure, preventing backflow caused by localized liquid accumulation. ② The length of bamboo pulp fibers (0.5-2mm) matches that of wood pulp fibers, and after mixing, they can form a looser three-dimensional network structure: the rigidity of bamboo pulp fibers is slightly higher than that of wood pulp fibers, which can play the role of "support skeleton" in the middle layer, reduce excessive collapse of the core when under pressure, and maintain the porosity between fibers (porosity increased by more than 15%); ③ The hollow structure and surface roughness of bamboo pulp fibers can enhance the binding force with CMC-coated SAP particles: the fiber surface near the hollow cavity can adsorb more SAP particles, preventing SAP from falling off or agglomerating under liquid impact; the hydrophilicity of bamboo pulp fibers is slightly higher than that of wood pulp fibers, which can transfer liquid to SAP particles faster through capillary action, improve their water absorption efficiency, and further alleviate the "gel blockage" problem.

[0033] Functional additives: The viscose fiber spinning solution contains nano zinc oxide (particle size 20-50nm, addition amount 0.3%-0.5%) modified with amphiphilic silane coupling agent, which is uniformly dispersed by melt blending; 0.5%-1% soluble pore-forming agent (such as PEG or sucrose) is added simultaneously, and after solidification, it forms through-pores.

[0034] Thermoplasticity and antibacterial properties: Viscose fiber contains 5%-8% polycaprolactone (PCL), which is thermoplastic below 80℃ and forms a dynamic hydrogen bond network with nano zinc oxide; the initial antibacterial rate against Escherichia coli and Staphylococcus aureus is >99%, and the antibacterial rate is still >90% after 5 washes.

[0035] Basic parameters: thickness 0.5-1.5mm, air permeability ≥5000mL / (cm²・s); cytotoxicity test shows cell viability >90%, meeting biocompatibility requirements.

[0036] The aforementioned "melt blending heating" is to achieve uniform dispersion of nano-zinc oxide and PCL in the spinning solution. Heating to above 80-120℃ is necessary to bring the viscose spinning solution into a low-viscosity flow state. Combined with mechanical shear force (such as screw agitation), the nano-zinc oxide (20-50nm) is "de-agglomerated" and uniformly dispersed. If the temperature is below 80℃, the high viscosity of the viscose matrix makes it difficult for shear force to be transmitted to the nanoparticles, easily leading to agglomeration. If the temperature exceeds 120℃, it may cause degradation of the viscose molecular chains or decomposition of the nano-zinc oxide surface modification layer (such as silane coupling agents), which would negatively impact performance. The above-mentioned pore-forming agent is dispersed in the viscose spinning solution at a ratio of 0.5%-1% (added simultaneously with nano zinc oxide and PCL). Because the pore-forming agent has good compatibility with the viscose matrix (cellulose derivative), it can be evenly distributed inside the fiber along with the spinning solution.

[0037] Fiber forming: After the spinning solution is extruded through the spinneret into the coagulation bath, the viscose matrix solidifies to form a fiber skeleton, and the pore-forming agent is "encapsulated" inside the fiber and forms along with the fiber.

[0038] Dissolution and Removal: During the washing process after molding, the pore-forming agent is dissolved in water and removed with the water flow, leaving regular pores in their original positions. This ultimately forms a continuous porous network structure in the underlying viscose layer. The removal of these pores during washing increases the specific surface area of ​​the viscose layer by more than 30%, significantly improving the antibacterial efficiency and liquid conductivity of nano-zinc oxide. Polyethylene Glycol: Possesses excellent water solubility, good compatibility with the viscose matrix, and a wide range of selectable molecular weights, such as PEG-4000 or PEG-6000. The resulting pore diameter is controllable, which is beneficial for adjusting the air permeability of the viscose fiber.

[0039] The hydrogen atoms (δ⁺) in the hydroxyl groups (-OH) on the surface of nano-zinc oxide form hydrogen bonds (OH…O) with the oxygen atoms (δ⁻) in the ester groups of the PCL molecular chains. This weak interaction "bridges" the PCL molecular chains and the nano-zinc oxide particles. When PCL is uniformly distributed in viscose fibers, a large number of PCL molecular chains and nano-zinc oxide particles are connected by hydrogen bonds, forming a network structure that runs through the entire viscose layer (similar to a collection of "molecular-level bridges").

[0040] The "dynamic hydrogen bond network" is essentially a "flexible connection system" formed by nano-zinc oxide and PCL through reversible hydrogen bonds. It not only achieves uniform dispersion and stable anchoring of nanoparticles, but also endows the material with composite properties such as shape memory, deformation resistance and long-term antibacterial effect through dynamic adjustment. It is the core molecular mechanism for the functional innovation of the lower adhesive layer.

[0041] The overall thickness of the composite structure is 3-8mm, and the water absorption ratio is 15-30 times. The reosmotic volume after absorbing 200 mL of physiological saline is <0.5 g; After being placed at 37℃ and 90% humidity for 72 hours, the total bacterial count was <10 CFU / g; After absorbing 200 mL of physiological saline, the thickness recovery rate was ≥85% after being pressed with 5 kg of pressure.

[0042] Segmented hydroentangling process: It adopts a three-stage process of "pre-needling - main needling - shaping needling". The pre-needling pressure is 5-8MPa to initially fix the interlayer position; the main needling pressure is 15-20MPa to achieve deep fiber entanglement; the shaping needling pressure is 8-10MPa, and a diamond pattern with a depth of 0.5mm and a spacing of 5mm is formed on the core surface by a patterned roller to enhance the surface conductivity and the adhesion to the outer layer material.

[0043] Low-temperature activation treatment: After hydroentangling, microwave activation is performed at 40-50℃ with a power of 300W for 2 minutes to promote hydrogen bonding between molecules of each layer of material, and the interlayer peel strength reaches 0.8N / 25mm.

[0044] (1) Preparation of the upper foaming material layer: The foaming material is hydrophilically modified by at least one of the above modification methods; (2) Preparation of intermediate wood pulp composite layer: wood pulp fiber and bamboo pulp fiber are mixed at a mass ratio of 7:3, and SAP particles with a particle size of 300-500μm are coated on the surface of the mixed fibers with a 2% CMC solution; (3) Preparation of the lower functional viscose layer: Add 0.3%-0.5% nano zinc oxide and 5%-8% PCL to the viscose fiber spinning solution; (4) Stack the above three layers of materials in sequence and composite them using a segmented hydroentanglement process: pre-punching pressure 5-8MPa, main punching pressure 15-20MPa, shaping punching pressure 8-10MPa, and use patterned rollers to form diamond patterns with a depth of 0.5mm and a spacing of 5mm. (5) After hydroentangling, the core is activated by microwave at 300W power for 2 minutes at 40-50℃ to obtain the absorber core composite structure. Example

[0045] Upper layer preparation: Polyurethane foam material was selected, and 7% acrylic monomer by weight of the matrix was added during the foaming stage. After molding, PVP was grafted after irradiation with 365nm ultraviolet light (100W) for 8 minutes; 4% hydrophilic nano-silica (particle size 30nm, specific surface area 200m² / g) was added simultaneously. The resulting upper layer has a basis weight of 25g / m², a surface pore size of 0.2mm, a pore size of 0.9mm at the interface of the lower layer, an open porosity of 92%, a density of 0.05g / cm³, a compression resilience of 88%, and a thickness of 1.2mm.

[0046] Intermediate layer preparation: Wood pulp and bamboo pulp fibers (1 mm in length and 7 μm in cavity diameter) were mixed in a 7:3 ratio. 400 μm SAP particles were coated onto the fiber surface using a 2% CMC solution (SAP addition amount 15%). The resulting intermediate layer had a basis weight of 60 g / m² and a thickness of 2.0 mm.

[0047] Lower layer preparation: 0.4% nano zinc oxide (particle size 35nm) and 7% PCL were added to the viscose spinning solution to prepare a functional viscose layer (gram weight 28g / m², thickness 0.8mm, air permeability 6000mL / (cm²・s)).

[0048] Composite molding: After the three layers are stacked, they are formed into a diamond pattern by segmented hydroentangling (pre-piercing 6MPa, main piercing 18MPa, shaping piercing 9MPa). After being activated by microwave at 300W at 45℃ for 2 minutes, a composite structure with an overall weight of 113g / m² and a thickness of 5mm is obtained.

[0049] Test results: water absorption ratio 25 times; absorption rate of 100mL physiological saline in 8 seconds; reabsorption after absorbing 200mL physiological saline 0.3g, diffusion length 130mm; total bacterial count <10CFU / g after 72 hours in an environment of 37℃ and 90% humidity; thickness recovery rate 90% after pressing with 5kg pressure. Example

[0050] Upper layer preparation: Polyethylene foam material was selected, and the surface was treated with plasma (300W, 3 minutes, oxygen atmosphere); 3% of a block copolymer additive containing polyethylene glycol segments (molecular weight 3000) was added. The resulting upper layer has a basis weight of 20 g / m², a surface pore size of 0.1 mm, a pore size of 0.8 mm at the interface of the lower layer, an open porosity of 90%, a density of 0.03 g / cm³, a compression resilience of 85%, and a thickness of 1.0 mm.

[0051] Intermediate layer preparation: Wood pulp and bamboo pulp fibers (0.5 mm in length and 5 μm in cavity diameter) were mixed in a 7:3 ratio. 300 μm SAP particles (10% SAP addition) were coated onto the fiber surface using a 2% CMC solution. The resulting intermediate layer had a basis weight of 40 g / m² and a thickness of 1.5 mm.

[0052] Lower layer preparation: 0.3% nano zinc oxide (particle size 20nm) and 5% PCL were added to the viscose spinning solution to prepare a functional viscose layer (gram weight 15g / m², thickness 0.5mm, air permeability 5000mL / (cm²・s)).

[0053] Composite molding: After the three layers are stacked, they are formed into a diamond pattern by segmented hydroentangling (pre-piercing 5MPa, main piercing 15MPa, and shaping piercing 8MPa). After being activated by microwave at 300W at 40℃ for 2 minutes, a composite structure with an overall weight of 75g / m² and a thickness of 3mm is obtained.

[0054] Test results: water absorption ratio of 15 times; absorption rate of 100mL physiological saline in 10 seconds; reabsorption after absorbing 200mL physiological saline in 0.4g, performance meets basic usage requirements. Example

[0055] Upper layer preparation: Polypropylene foam material was selected, and 6% acrylic monomer (by weight of the matrix) was added during the foaming stage. After molding, it was irradiated with 365nm ultraviolet light (100W power) for 7 minutes to initiate the grafting of polyvinylpyrrolidone. Simultaneously, 3.5% hydrophilic nano-silica (particle size 40nm, specific surface area 250m² / g) was added. The final upper layer had a basis weight of 22g / m², a surface pore size of 0.15mm, a pore size of 0.85mm at the lower layer interface, an open porosity of 91%, a density of 0.04g / cm³, a compression resilience of 86%, and a thickness of 1.1mm.

[0056] Intermediate layer preparation: Wood pulp and bamboo pulp fibers (1.5 mm in length and 8 μm in cavity diameter) were mixed at a mass ratio of 7:3. SAP particles with a particle size of 350 μm (SAP addition amount: 12%) were then coated onto the fiber surface using a 2% sodium carboxymethyl cellulose solution. The resulting intermediate layer had a basis weight of 50 g / m² and a thickness of 1.8 mm.

[0057] Lower layer preparation: 0.35% nano zinc oxide (particle size 30nm) and 6% polycaprolactone were added to the viscose spinning solution to prepare a functional viscose layer (gram weight 22g / m², thickness 0.6mm, air permeability 5500mL / (cm²・s)).

[0058] Composite molding: The three layers are stacked in sequence and then subjected to segmented hydroentangling (pre-piercing pressure set at 7MPa, main piercing pressure at 17MPa, and shaping piercing pressure at 8.5MPa) to form a diamond pattern. After that, it is activated by microwave at 300W power for 2 minutes at 42℃ to obtain a composite structure with an overall weight of 94g / m² and a thickness of 3.5mm.

[0059] Test results: The water absorption ratio reached 20 times; the absorption rate of 100mL of physiological saline was 9 seconds; after absorbing 200mL of physiological saline, the reabsorption amount was 0.35g and the diffusion length was 125mm; after being placed in an environment of 37℃ and 90% humidity for 72 hours, the total bacterial count was <10CFU / g; after being pressed with 5kg pressure, the thickness recovery rate was 91%. Example

[0060] This embodiment provides a hygiene product, which includes at least a surface layer and an absorbent core layer. The surface layer is made of a nonwoven fabric for insulation and soothing, and the absorbent core layer is the absorbent core composite structure prepared in the embodiments 1-3 above.

[0061] The above-mentioned method for preparing the insulating and soothing nonwoven fabric includes the following steps: 1) Pre-treatment of ES fiber web surface to form a positively charged nanoscale mesh pre-coating on the fiber surface: ES fiber is treated in an alkaline solution at 55°C for 15 minutes to etch the fiber surface to form a microgroove structure. Then, natural cationic polysaccharides are adsorbed on the fiber surface by padding to form a positively charged nanoscale mesh pre-coating, which enhances the adhesion of subsequent materials. Natural cationic polysaccharides are also used to electrostatically destroy the cell membrane of microorganisms to increase biocompatibility.

[0062] 2) Construct a dynamic slow-release composite mineralization layer outside the nanoscale mesh pre-coating: Prepare a solution containing zinc gluconate, immerse the pretreated ES fibers in it, and induce the growth of hydroxyapatite (HA) nanocrystals by ultrasound at 40°C and pH 8.2. Soothing ingredients (panthenol, dipotassium glycyrrhizate, ceramide NP, and purslane extract) are simultaneously embedded in the HA lattice. During the mineralization process, zinc gluconate and soothing ingredients form coordination bonds with HA, achieving the slow release of zinc ions and exerting anti-inflammatory and soothing effects.

[0063] 3) Constructing a gradient pore structure on the fiber mesh of the mineralized layer, including: The fiber web loaded with mineralized layer is subjected to bidirectional gradient stretching. The upper layer stretching ratio is controlled at 1.8:1 to form a fine structure with a pore size of 5-10μm, which prevents liquid backflow. The lower layer (contact absorption core) stretching ratio is increased to 2.5:1 to form a loose structure with a pore size of 15-20μm, which accelerates liquid infiltration. Meanwhile, during the hot pressing and setting stage (temperature 125℃, pressure 0.8MPa), the low melting point of ES fiber is utilized to partially melt the fiber intersections, constructing a stable three-dimensional porous skeleton, and increasing the air permeability to 4500-6000mm / s.

[0064] 4) Preparation of self-crosslinking adhesive interfaces: A two-component adhesive layer composed of methacrylamide gelatin (GelMA) and sodium alginate is coated on the bottom surface of the nonwoven fabric surface. A trace amount of CaCO3 (0.1%-1%) is added to the core encapsulation layer. When in contact with liquid, the hydroxyl and amino groups of methacrylamide gelatin (GelMA) can form hydrogen bonds with the carboxyl groups of sodium alginate, enhancing compatibility with sodium alginate. Simultaneously, the ionic cross-linking network of sodium alginate and calcium ions is embedded in the network structure of GelMA, forming a triple effect of "hydrogen bond assistance + physical entanglement + chemical cross-linking," achieving a peel strength of 10-25 N / 25 mm, effectively preventing surface layer displacement during use. This design directly relies on the gradient pore structure of the third step. The fine pores in the upper layer control the liquid contact rate, allowing the cross-linking reaction to proceed gently and avoiding excessive cross-linking that leads to brittleness. The loose pores in the lower layer quickly guide the liquid to the core, ensuring continuous release of Ca²⁺ to maintain adhesive strength, forming a closed-loop support of "structure-function-stability."

[0065] Experimental example: Materials preparation: Substrate: ES fiber (20g / m²) Reagents: 0.5% NaOH solution, chitosan quaternary ammonium salt (molecular weight 50 kDa), zinc gluconate (purity 99%), hydroxyapatite precursor (Ca / P = 1.67), panthenol (purity 98%), dipotassium glycyrrhizate (purity 95%), ceramide NP (purity 90%), purslane extract (concentration 10%), methacrylamide gelatin (GelMA, degree of substitution 70%), sodium alginate (low viscosity), CaCO3 powder (particle size 5 μm). Implementation steps: 1. ES fiber surface pretreatment: ES fiber mesh was immersed in a 0.5% NaOH solution at 55℃ and magnetically stirred for 15 minutes. It was then removed and rinsed with deionized water until neutral. The fiber mesh was then immersed in a 2% chitosan quaternary ammonium salt solution (pH 6.5) using a pad-dip method (80% roll-off). After air-drying at room temperature, a positively charged nano-mesh pre-coating was formed. The zeta potential of the fiber surface was measured to be +35mV, and the groove depth was approximately 200nm.

[0066] 2. Construction of a dynamically released composite mineralization layer: A mixture containing 0.1 mol / L zinc gluconate, 0.05% panthenol, 0.03% dipotassium glycyrrhizate, 0.02% ceramide NP, and 0.1% purslane extract was prepared, and the pH was adjusted to 8.2. The pretreated ES fiber mesh was immersed in the mixture and reacted in an ultrasonic cleaner (40 kHz, 100 W) at 40 °C for 30 minutes to induce HA nanocrystal growth. After the reaction, the fiber mesh was removed and vacuum dried at 60 °C. The mineralized layer thickness was measured to be 150 nm, and the HA crystallinity was 75%.

[0067] 3. Gradient pore structure formation: The fiber web with the mineralized layer was fixed to a biaxial stretching device. The upper layer (skin contact surface) was stretched laterally at a stretch ratio of 1.8:1, and the lower layer (core contact surface) was stretched longitudinally at a stretch ratio of 2.5:1, maintaining a tension of 30N. It was then transferred to a hot press setting machine and processed at 125℃ and 0.8MPa for 10 seconds. After cooling, the pore size of the upper layer was measured to be 7μm and the pore size of the lower layer was 18μm. 4. Self-crosslinking adhesive interface design: A GelMA / sodium alginate mixture (mass ratio 3:1, solid content 15%) was coated on the reverse side of the fiber mesh layer (skin contact surface), with a coating thickness of 20 μm. The core wrapping layer was uniformly sprayed with a 0.5% CaCO3 suspension (solvent: 50% ethanol), dried at room temperature, and then assembled.

[0068] The test results of the experimental material properties are as follows:

[0069] In this embodiment, disposable hygiene products such as sanitary napkins and diapers are designed with an insulating and soothing surface layer. Using ES fiber as the base material, a dynamic slow-release composite system is employed to embed anti-inflammatory factors into a biomimetic mineralization layer, achieving continuous release of ingredients. A gradient pore breathable structure is constructed, with a denser pore size distribution at the top and a looser one at the bottom achieved through bidirectional stretching, ensuring rapid liquid penetration while maintaining good breathability. A self-crosslinking adhesive interface is developed, allowing the surface layer and absorbent core to chemically bond upon contact with liquid, achieving the insulating and soothing effect. The composite core structure, combining the aforementioned foaming material with a rapidly absorbing liquid storage layer, constructs a highly synergistic liquid management system. The gradient design between layers ensures smooth liquid transfer and progressively enhances absorbency. Each layer is interlocked, with mutual structural strength support, resulting in a soft and thin overall core.

[0070] The present invention has been described in detail above, but it is not limited to the embodiments described above. Various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the invention. Many other changes and modifications made without departing from the concept and scope of the invention should be considered within the scope of protection of the present invention.

[0071] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An absorber core composite structure, characterized in that, It consists of an upper layer of hydrophilic long-lasting modified foam material, a middle layer of wood pulp composite material, and a lower layer of functional adhesive material; the upper, middle, and lower layers are composited by a segmented hydroentangling process and low-temperature activation treatment.

2. The absorber core composite structure according to claim 1, characterized in that, The upper foaming material is selected from at least one of polyurethane, polyethylene, polypropylene, polyester, polyether, silicone rubber, or rubber-based foaming materials; the hydrophilic long-lasting modification is performed using at least one of the following methods: (a) During the foaming stage, 5%-8% of acrylic monomers by weight of the matrix are introduced. After molding, the grafting of polyvinylpyrrolidone is initiated by irradiation with 365nm ultraviolet light for 5-10 minutes. (b) The surface is treated with plasma to form oxygen-containing polar groups. The treatment conditions are 200-500W power and 1-5 minutes time, and the gas is oxygen or air. (c) Disperse and add 3%-5% by mass of hydrophilic nano-silica particles with a particle size of 10-50nm and a specific surface area of ​​100-300m² / g; (d) Use block copolymers containing polyethylene glycol segments as foaming aids. The molecular weight of the polyethylene glycol segments is 1000-5000, and the amount added is 2%-4% of the matrix mass.

3. The absorber core composite structure according to claim 2, characterized in that, The upper foam material has a contact angle of less than 40 degrees after 5 water washes; the pore size is gradient distributed along the thickness direction, with a pore size of 0.1-0.3 mm on the upper surface and 0.8-1 mm at the lower interface (the joint surface between the upper and middle layers); the open porosity is > 90%, the density is 0.03-0.08 g / cm³, and the compression resilience is ≥ 85%.

4. The absorber core composite structure according to claim 1, characterized in that, The intermediate layer is a mixture of wood pulp fiber and bamboo pulp fiber at a mass ratio of 7:

3. The bamboo pulp fiber has a length of 0.5-2 mm and a hollow structure cavity diameter of 5-10 μm. The intermediate layer is also coated with superabsorbent polymer particles with a concentration of 2% sodium carboxymethyl cellulose solution on the surface of the wood pulp fiber. The superabsorbent polymer particles have a particle size of 300-500 μm and the amount added is ≤20% of the mass of the intermediate layer.

5. The absorber core composite structure according to claim 1, characterized in that, The viscose fiber spinning solution of the lower functional viscose layer contains nano-zinc oxide modified with an amphiphilic silane coupling agent, with an addition amount of 0.3%-0.5%; 0.5%-1% of a soluble pore-forming agent is added to the spinning solution simultaneously; the viscose fiber contains 5%-8% polycaprolactone, which forms a dynamic hydrogen bond network with the nano-zinc oxide.

6. The absorber core composite structure according to claim 1, characterized in that, The segmented hydroentangling process includes: pre-piercing pressure of 5-8 MPa, main piercing pressure of 15-20 MPa, and shaping piercing pressure of 8-10 MPa; forming a diamond pattern with a depth of 0.5 mm and a spacing of 5 mm on the core surface using a patterned roller.

7. The absorber core composite structure according to claim 1, characterized in that, The low-temperature activation treatment is performed by microwave activation at 40-50℃ after hydroentangling, with a power of 300W and a time of 2 minutes, resulting in an interlayer peel strength ≥0.8N / 25mm.

8. A method for preparing an absorber core composite structure, characterized in that, The method includes: (1) Prepare an upper foam material layer and modify the foam material to be hydrophilic by at least one modification method; (a) During the foaming stage, 5%-8% of acrylic monomers by weight of the matrix are introduced. After molding, the grafting of polyvinylpyrrolidone is initiated by irradiation with 365nm ultraviolet light for 5-10 minutes. (b) The surface is treated with plasma to form oxygen-containing polar groups. The treatment conditions are 200-500W power and 1-5 minutes time, and the gas is oxygen or air. (c) Disperse and add 3%-5% by mass of hydrophilic nano-silica particles with a particle size of 10-50nm and a specific surface area of ​​100-300m² / g; (d) Block copolymers containing polyethylene glycol segments are used as foaming agents. The molecular weight of the polyethylene glycol segments is 1000-5000, and the addition amount is 2%-4% of the matrix mass. (2) Preparation of intermediate wood pulp composite layer: wood pulp fiber and bamboo pulp fiber are mixed at a mass ratio of 7:3, and SAP particles with a particle size of 300-500μm are coated on the surface of the mixed fibers with a 2% CMC solution; (3) Preparation of the lower functional viscose layer: Add 0.3%-0.5% nano zinc oxide and 5%-8% PCL to the viscose fiber spinning solution; (4) Stack the above three layers of materials in sequence and composite them using a segmented hydroentanglement process: pre-punching pressure 5-8MPa, main punching pressure 15-20MPa, shaping punching pressure 8-10MPa, and use patterned rollers to form diamond patterns with a depth of 0.5mm and a spacing of 5mm. (5) After hydroentangling, the absorber core composite structure is obtained by microwave activation at 300W power for 2 minutes at 40-50℃.

9. The absorber core composite structure according to any one of claims 1-7, characterized in that, It is applied to hygiene products, medical care products, or industrial absorbent materials; the hygiene products include diapers, sanitary napkins, nursing pads, adult incontinence products, or medical dressings; the hygiene products include a surface layer and an absorbent core layer, the surface layer being a surface layer made of insulating and soothing nonwoven fabric; the absorbent core layer adopts the absorbent core composite structure described in any one of claims 1-9.

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