Skin-friendly antibacterial ammonia-inhibiting diaper cover layer, preparation method thereof and diaper

Abstract

This invention discloses a skin-friendly, antibacterial, and ammonia-inhibiting diaper surface layer, its preparation method, and the diaper itself. The surface layer is formed from composite fibers; the composite fibers include a core layer and a sheath layer covering the outside of the core layer. The sheath layer is formed by melt spinning a polyethylene masterbatch and a non-leaching physical antibacterial masterbatch; the core layer is formed by melt spinning a polyethylene terephthalate masterbatch. The non-leaching physical antibacterial masterbatch includes a polyethylene carrier and nano-composite antibacterial powder dispersed in the polyethylene carrier. This invention directionally loads the nano-composite antibacterial powder onto the sheath layer, making the sheath layer a soft, skin-friendly contact surface with antibacterial and ammonia-inhibiting functions. The rigid PET core layer provides mechanical support and avoids ineffective consumption of functional masterbatch, thus enabling the diaper surface layer to possess softness, fluffiness, structural stability, and high utilization rate of functional components.

Description

Technical Field

[0001] This invention belongs to the technical field of infant hygiene care products, specifically relating to a skin-friendly, antibacterial, and ammonia-inhibiting diaper surface layer, its preparation method, and the diaper itself. Background Technology

[0002] Disposable diapers are commonly used disposable hygiene products in the daily care of infants and young children. They typically consist of a skin-friendly top layer, a distribution layer, an absorbent core, and a breathable bottom layer. Among these, the skin-friendly top layer is located on the side closest to the infant's skin and is in direct contact with the skin, urine, and feces. Its softness, dryness, breathability, and hygiene directly affect the comfort of wearing the diaper and the health of the infant's skin.

[0003] During diaper use, urine and feces are absorbed or retained inside the diaper, easily creating a moist, warm, and relatively enclosed local environment near the skin-contacting surface. This environment not only easily causes maceration of the skin's stratum corneum and a decline in its barrier function, but also creates conditions for the proliferation of bacteria, fungi, and other pathogenic microorganisms. Especially in cases of diarrhea, frequent bowel movements, or infrequent diaper changes in infants, irritating substances such as proteases and lipases in feces can interact with urine and microorganisms, exacerbating skin irritation and inflammatory responses, thereby increasing the risk of diaper dermatitis, skin redness, erosion, and secondary infections.

[0004] Urea in urine is easily decomposed into ammonia by microorganisms on the skin surface, in feces, or other urea-decomposing bacteria. The accumulation of ammonia inside diapers increases the irritation of the local environment and has a lasting impact on the delicate skin of infants, making it a significant factor in causing or worsening diaper rash. Meanwhile, feces and the perianal environment may contain bacteria or fungi such as Escherichia coli, Staphylococcus aureus, Streptococcus, and Candida albicans. Their continuous reproduction under warm and humid conditions can further disrupt the local microenvironment, making the skin barrier more susceptible to secondary infections. Some fecal-associated viruses may also come into contact with the diaper surface through excrement, increasing the risk of contact transmission and skin irritation during periods of diarrhea or when the skin is broken.

[0005] Current disposable diapers primarily rely on the absorbent core to absorb and retain urine, while the skin-friendly surface mainly serves to guide, isolate, and improve the feel of the diaper. For ordinary disposable diapers, their functions are mostly focused on absorbency, leak prevention, breathability, and a secure fit, with insufficient ability to inhibit the growth of microorganisms, ammonia production from urea decomposition, and fecal-related pathogens in the urine and feces contact area. Therefore, when the inside of the diaper is damp and hot, there may still be problems such as continuous microbial growth, ammonia generation, and increased skin irritation, making it difficult to reduce the risk of diaper rash and related infections at the source.

[0006] To improve the hygienic performance of diaper surface layers, existing technologies include spraying, impregnating, or finishing antibacterial agents onto the nonwoven fabric surface, as well as adding silver ions, zinc ions, copper ions, organic antibacterial agents, plant extracts, or other antibacterial materials to the fiber raw materials. While these methods can inhibit microbial growth to some extent, some antibacterial systems rely on the migration and release of antibacterial ions or small organic molecules to achieve their antibacterial effect. Long-term use may lead to problems such as component migration, precipitation, odor residue, functional degradation, or skin irritation. For diaper products that are worn close to the skin by infants for extended periods, these issues can affect their safety and gentleness.

[0007] Furthermore, organic antibacterial agents, plant extracts, and quaternary ammonium salt antibacterial agents may exhibit insufficient thermal stability during high-temperature spinning or hot-air molding, easily leading to decreased antibacterial performance or poor processing compatibility. Some organic antibacterial systems have limited effectiveness in dry or low-humidity conditions, making it difficult to maintain stable antibacterial effects in environments where the diaper surface layer alternates between dry, semi-dry, and wet states. If antibacterial agents are applied to the surface layer through finishing processes, they may detach or migrate during urine rinsing, friction, or long-term storage, resulting in insufficient antibacterial durability.

[0008] Existing inorganic antibacterial fibers or antibacterial nonwoven fabrics typically employ an integral blending method to incorporate antibacterial powder into the fiber raw materials, dispersing the functional components throughout the fiber's cross-section. However, for core-sheath composite fibers or similar composite fibers, if the antibacterial components are also distributed in the core layer, a significant portion of these components cannot fully contact urine, feces, and the microorganisms within them, resulting in a low effective utilization rate of the functional components.

[0009] Existing antibacterial diaper surface layers also have shortcomings in inhibiting ammonia production. Some products mainly reduce odor by increasing absorption speed, expanding absorbent core capacity, or adding odor-absorbing materials. Their focus is usually on absorbing or masking existing odors, rather than inhibiting the growth of urea-decomposing bacteria and other ammonia-producing microorganisms in the skin-contact area. Since urine and feces first come into contact with the skin-contact surface layer, if the activity of ammonia-producing microorganisms cannot be effectively inhibited in this area, ammonia may still continue to be generated in the local environment and irritate the skin. Summary of the Invention

[0010] The purpose of this invention is to provide a skin-friendly, antibacterial, and ammonia-inhibiting diaper surface layer, its preparation method, and the diaper itself. This invention involves directionally loading a non-leaching physical antibacterial masterbatch into the sheath layer of a core-sheath composite fiber structure, giving the diaper's skin-friendly surface layer a combination of softness, breathability, non-leaching physical antibacterial and antiviral properties, and ammonia inhibition at the source, thereby reducing irritants associated with diaper dermatitis and the contact load of fecal pathogens in infants.

[0011] In a first aspect, the present invention provides a skin-friendly, antibacterial, and ammonia-inhibiting diaper surface layer, which is formed by composite fibers; the composite fibers include a core layer and a sheath layer covering the outside of the core layer. The sheath layer is formed by melt spinning polyethylene masterbatch and non-leaching physical antibacterial masterbatch; the core layer is formed by melt spinning polyethylene terephthalate masterbatch.

[0012] The non-leaching physical antibacterial masterbatch includes a polyethylene carrier and nanocomposite antibacterial powder dispersed in the polyethylene carrier; the nanocomposite antibacterial powder includes nanoporous hexagonal boron nitride, molybdenum disulfide nanosheets, nanozirconium oxide and hydrophobic nano silica.

[0013] The polyethylene sheath is located on the outer surface of the composite fiber and is used to form a contact area that comes into contact with urine and / or feces, so that the non-leaching physical antibacterial masterbatch is concentrated in the contact area.

[0014] Preferably, in the nanocomposite antibacterial powder, the mass fraction of nanoporous hexagonal boron nitride is 70wt% to 85wt%; the mass fraction of molybdenum disulfide nanosheets is 8wt% to 18wt%; the mass fraction of nanozirconium oxide is 3wt% to 10wt%; and the mass fraction of hydrophobic nano silica is 2wt% to 8wt%.

[0015] Preferably, the nanocomposite antibacterial powder comprises, by weight percentage: 78wt% nanoporous hexagonal boron nitride, 12wt% few-layer molybdenum disulfide nanosheets, 6wt% nanozirconium oxide and 4wt% hydrophobic nano silica.

[0016] Preferably, the non-leaching physical antibacterial masterbatch comprises, by weight percentage: 15wt%–35wt% nanocomposite antibacterial powder, 55wt%–80wt% polyethylene carrier, 1wt%–5wt% silane coupling agent, and 1wt%–5wt% high-temperature resistant lubricant.

[0017] Preferably, in the non-leaching physical antibacterial masterbatch, the mass fraction of nanocomposite antibacterial powder is 25wt%, the mass fraction of polyethylene carrier is 70wt%, the mass fraction of KH-550 silane coupling agent is 3wt%, and the mass fraction of high-temperature resistant lubricant is 2wt%.

[0018] Preferably, the mass ratio of non-leaching physical antibacterial masterbatch to polyethylene carrier in the raw materials used to form the skin layer is (4-5.5):100;

[0019] Preferably, the composite fiber has a fineness of 0.8 dtex to 2.0 dtex. The specific surface area of ​​the composite fiber is 1.8 m². 2 / g~2.2m 2 / g; The mass ratio of the non-leaching physical antibacterial masterbatch to the polyethylene carrier in the cortex increases with the increase of the specific surface area of ​​the composite fiber.

[0020] Preferably, the mass ratio of the outer layer to the core layer is 3.5:6.5; the diaper outer layer is made of hot-air nonwoven fabric with a basis weight of 20 g / m². 2 ~30g / m 2 .

[0021] Secondly, the present invention provides a preparation method for preparing the aforementioned skin-friendly, antibacterial, and ammonia-inhibiting diaper surface layer. The preparation method includes:

[0022] A nanocomposite antibacterial powder was obtained by mixing nanoporous hexagonal boron nitride, molybdenum disulfide nanosheets, nanozirconium oxide, and hydrophobic nano silica.

[0023] The nanocomposite antibacterial powder is mixed with a polyethylene carrier and melt-granulated to obtain a non-leaching physical antibacterial masterbatch.

[0024] Polyethylene masterbatch is melt-mixed with non-leaching physical antibacterial masterbatch to form a skin-layer composite melt;

[0025] The polyethylene terephthalate masterbatch is melted to form the core layer melt;

[0026] Composite spinning is performed using a sheath-core composite melt and a core melt to obtain composite fibers with a sheath-core structure.

[0027] The composite fibers are processed into nonwoven fabric to obtain the skin-friendly, antibacterial, and ammonia-inhibiting diaper surface layer.

[0028] Preferably, when preparing the non-leaching physical antibacterial masterbatch, the nanocomposite antibacterial powder, polyethylene carrier, silane coupling agent and high-temperature lubricant are mixed and then melt-blended and extruded into granules.

[0029] Preferably, during the composite spinning process, the spinning temperature of the outer layer is 230℃~250℃, and the spinning temperature of the core layer is 280℃~290℃; the nonwoven fabric forming process includes opening, web laying and hot air bonding; the temperature of the hot air bonding is 250℃~280℃.

[0030] Preferably, during the composite spinning process, the sheath composite melt and the core melt respectively enter the composite spinning assembly, and the sheath composite melt covers the outside of the core melt in the composite spinning assembly, forming a composite fiber with a sheath-core structure after being spun into fibers.

[0031] Thirdly, the present invention provides a diaper, which includes a diaper body, the diaper body comprising a skin-friendly surface layer, a diversion layer, an absorbent core and a breathable bottom layer arranged sequentially from the inside to the outside; the skin-friendly surface layer is the aforementioned skin-friendly antibacterial and ammonia-inhibiting diaper surface layer.

[0032] Preferably, the absorbent core comprises superabsorbent polymer and fluff pulp, and the breathable bottom layer comprises a breathable waterproof membrane and an outer nonwoven fabric.

[0033] Compared with the prior art, the present invention has at least the following beneficial effects:

[0034] 1. This invention employs a composite fiber structure in which a PE single-layer coating is used to cover a PET rigid core layer, and nano-composite antibacterial powder is oriented and loaded onto the PE single-layer coating. This results in a soft, skin-friendly contact surface with antibacterial and ammonia-inhibiting functions, while the PET rigid core layer provides mechanical support and avoids the ineffective consumption of functional masterbatch. As a result, the diaper surface layer combines softness, fluffiness, structural stability, and high efficiency of functional component utilization.

[0035] 2. This invention forms a nanocomposite antibacterial powder by using nanoporous hexagonal boron nitride, few-layer molybdenum disulfide nanosheets, nanozirconium oxide, and hydrophobic nano silica. By utilizing porous adsorption, physical disturbance at the edges of the sheets, and structural stabilization, it produces contact inhibition or destruction of bacteria, fungi, and viruses, thereby achieving non-leaching antibacterial and antiviral effects.

[0036] 3. This invention inhibits the survival and reproduction of urea-decomposing bacteria and other ammonia-producing microorganisms through non-leaching physical antibacterial masterbatch, and combines the adsorption and retention effect of porous nanomaterials on ammonia or ammonia-containing metabolites to reduce ammonia production from the source, thereby reducing the irritation of ammonia to infants' skin.

[0037] 4. This invention improves the dryness and low friction properties of the fiber surface by using hydrophobic nano-silica and few-layer molybdenum disulfide nanosheets, reducing the retention of urine on the surface layer, thereby weakening the conditions for microbial growth and continuous ammonia production in a humid and hot environment.

[0038] 5. This invention adjusts the addition ratio of non-leaching physical antibacterial masterbatch according to the specific surface area of ​​composite fibers, so that the distribution of antibacterial sites matches the fiber contact area, thereby improving the antibacterial, antifungal and antiammonia effects while avoiding excessive addition that could lead to surface hardening or reduced air permeability. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the composite fiber cross-sectional structure of the surface layer of a skin-friendly, antibacterial, and ammonia-inhibiting diaper provided in Embodiment 1 of the present invention.

[0040] Figure 2A schematic diagram of the preparation process of the skin-friendly, antibacterial, and ammonia-inhibiting diaper surface layer is provided for Embodiment 1 of the present invention.

[0041] Figure 3 A structural schematic diagram of a diaper is provided for Embodiment 4 of the present invention.

[0042] Reference numerals: 1. Skin-friendly top layer; 2. Diversion layer; 3. Absorbent core; 4. Breathable bottom layer; 5. Elastic waistband; 6. Adhesive component; 7. Leak-proof side guard. Detailed Implementation

[0043] The present invention will be further described below with reference to embodiments. It should be understood that the following embodiments are used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Without departing from the concept of the present invention, those skilled in the art can make appropriate adjustments to the specific materials, proportions and process parameters.

[0044] Example 1

[0045] A skin-friendly, antibacterial, and ammonia-inhibiting diaper surface layer is made of composite fibers. For example... Figure 1 As shown, the composite fiber comprises a PE single-layer sheath and a PET rigid core layer. The PE single-layer sheath wraps around the outer periphery of the PET rigid core layer. The PE single-layer sheath forms the surface area that directly contacts the infant's skin, urine, and feces; the PET rigid core layer provides mechanical support to the PE single-layer sheath.

[0046] In this embodiment, the PE single-layer sheath is formed by melt spinning a food-grade low-density polyethylene masterbatch and a non-leaching physical antibacterial masterbatch containing nano-composite antibacterial powder. The PET rigid core layer is made of polyethylene terephthalate resin masterbatch. The melting point of the PET rigid core layer is 280°C to 300°C, and the mass ratio of the PE single-layer sheath to the PET rigid core layer is 3.5:6.5.

[0047] In this embodiment, the raw materials for preparing the diaper surface layer include, by weight: 500 parts of polyethylene masterbatch, 900 parts of polyethylene terephthalate masterbatch, 23 parts of non-leaching physical antibacterial masterbatch, and an appropriate amount of spinning aid. In this embodiment, the addition ratio of non-leaching physical antibacterial masterbatch to polyethylene masterbatch is 4.6 wt%, and the specific surface area of ​​the resulting composite fiber is 2.0 m². 2 / g.

[0048] The non-leaching physical antibacterial masterbatch comprises, by weight percentage: 25wt% nanocomposite antibacterial powder, 70wt% food-grade low-density polyethylene carrier, 3wt% KH-550 silane coupling agent, and 2wt% ultra-dispersed high-temperature resistant lubricant.

[0049] The nanocomposite antibacterial powder comprises, by weight percentage: 78 wt% nanoporous hexagonal boron nitride, 12 wt% few-layer molybdenum disulfide nanosheets, 6 wt% nano-zirconia, and 4 wt% hydrophobic nano-silica. In this embodiment, the few-layer molybdenum disulfide nanosheets refer to MoS2 sheet materials with 2 to 10 layers; in some embodiments, the thickness of the few-layer molybdenum disulfide nanosheets is 1 nm to 10 nm, and the sheet diameter is 50 nm to 500 nm.

[0050] like Figure 2 As shown, the diaper surface layer of this embodiment is prepared according to the following steps:

[0051] Step 1: Prepare nanocomposite antibacterial powder.

[0052] Weigh out 78 wt% porous hexagonal boron nitride, 12 wt% few-layer molybdenum disulfide nanosheets, 6 wt% nano-zirconia, and 4 wt% hydrophobic nano-silica, and premix the components to obtain a nanocomposite antibacterial powder. Premixing can be performed using a high-speed mixer to initially disperse the nanoparticles before they enter the masterbatch carrier.

[0053] In some embodiments, the dimensions of the components in the nanocomposite antibacterial powder are as follows:

[0054] (1) Nanoporous hexagonal boron nitride: particle size 0.5-2 μm, pore size 2-10 nm, specific surface area ≥150 m² 2 / g, which relies on mesoporous porous structure to achieve efficient loading of functional powders, improve functional utilization, and at the same time match spinning, filtration and extrusion conditions to avoid clogging of the screen by ultrafine powders.

[0055] (2) Few-layered molybdenum disulfide nanosheets: with a lateral dimension of 100-500 nm and a thickness of 1-5 nm (few-layered structure). The two-dimensional layered structure is used to achieve melt lubrication and functional synergy, improve spinning fluidity, and avoid the problem of nanosheet agglomeration.

[0056] (3) Nano-zirconia: Particle size is 20-100nm (tetragonal phase, yttrium oxide stable type). The powder has excellent dispersibility and stable structure, and is suitable for high-temperature masterbatch blending and spinning processing. There is no risk of agglomeration or precipitation.

[0057] (4) Hydrophobic nano-silica: with a particle size of 10-50 nm. The hydrophobic nano-silica is modified with silane, and has a hydrophobic contact angle ≥120°, which can significantly improve the hydrophobic and antibacterial properties of the fiber, while optimizing the melt rheological properties and improving the high-temperature spinning fluidity and molding uniformity.

[0058] Step 2: Prepare non-leaching physical antibacterial masterbatch.

[0059] Weigh out each component: 25wt% nanocomposite antibacterial powder, 70wt% food-grade low-density polyethylene carrier, 3wt% KH-550 silane coupling agent, and 2wt% ultra-dispersed high-temperature resistant lubricant. Add the above components into a mixing device and mix to obtain a masterbatch premix.

[0060] The premixed masterbatch is added to a twin-screw extruder for melt mixing and extrusion granulation to obtain a non-leaching physical antibacterial masterbatch. During the twin-screw extrusion process, the nanocomposite antibacterial powder is coated and dispersed by a food-grade low-density polyethylene carrier. KH-550 silane coupling agent improves the bonding stability between the powder and the carrier, and ultra-dispersed high-temperature resistant lubricant reduces powder agglomeration and processing friction, thereby obtaining masterbatch granules suitable for PE single-layer spinning.

[0061] In some embodiments, the melt spinning temperature range of the polyethylene skin in this invention is 270℃~300℃. To adapt to the high-temperature spinning system and ensure the stability of melt processing and the performance of the finished fiber, a high-temperature resistant modified polypropylene wax and high-temperature resistant modified polyether silicone oil compound system is used as a super-dispersed high-temperature resistant lubricant. The specific material parameters and technical effects are detailed below:

[0062] (1) Main lubricant: Modified polypropylene wax (PP-WAX)

[0063] The modified polypropylene wax has a melting point of 160℃~170℃ and a thermal decomposition temperature ≥320℃. It remains structurally stable, does not decompose, and releases no odor even under high-temperature spinning conditions of 270℃~300℃. Simultaneously, the modified polypropylene wax possesses both lubricating and powder dispersing properties, significantly improving the dispersion uniformity of nano-functional powders in polyethylene melt, effectively inhibiting powder agglomeration, and eliminating spinning web clogging defects. Furthermore, this material exhibits good compatibility with the polyethylene matrix and will not negatively affect fiber continuity, fiber mechanical properties, or the final antibacterial and antiviral functions.

[0064] (2) Auxiliary lubricant: High-temperature modified polyether silicone oil

[0065] The high-temperature modified polyether silicone oil has a temperature resistance of ≥300℃, making it suitable for the complete high-temperature spinning process in this embodiment. It can effectively reduce the shear viscosity of the polymer melt, decrease the melt flow friction resistance, and improve the uniformity and spinning stability of the filaments.

[0066] Step 3: Prepare PE single-layer melt and PET rigid core melt.

[0067] Polyethylene masterbatch, non-leaching physical antibacterial masterbatch and spinning aid are added to the extrusion section of PE single-layer, so that the non-leaching physical antibacterial masterbatch and polyethylene masterbatch are melted and mixed to form PE single-layer melt.

[0068] Polyethylene terephthalate masterbatch is added to the extrusion section of the PET rigid core layer to form the PET rigid core layer melt. No non-leaching physical antibacterial masterbatch is added to the extrusion section of the PET rigid core layer.

[0069] Step 4: Composite spinning to form PE single-layer ES composite fiber.

[0070] A twin-screw split-spinning process is adopted, allowing the PE single-layer melt and the PET rigid core melt to enter the composite spinning assembly separately. The spinning temperature of the PE single-layer is controlled between 230℃ and 250℃, the spinning temperature of the PET rigid core is controlled between 280℃ and 290℃, and the melt pressure is controlled between 13MPa and 15MPa.

[0071] After being extruded by the composite spinning assembly, the PE single-layer sheath covers the outside of the PET rigid core layer, forming a composite fiber.

[0072] In the aforementioned composite spinning process, the non-leached physical antibacterial masterbatch only enters the PE single-layer and not the PET rigid core layer, allowing the non-leached physical antibacterial masterbatch to be directionally loaded onto the PE single-layer. Since the PE single-layer is located on the outer surface of the composite fibers, the non-leached physical antibacterial masterbatch can be concentrated in the contact area of ​​the diaper's surface layer, thereby improving its contact efficiency with urine, feces, and microorganisms. The PET rigid core layer does not contain the non-leached physical antibacterial masterbatch, avoiding the ineffective consumption of antibacterial functional components in the core layer and helping to reduce material costs.

[0073] Step 5: Hot air nonwoven fabric forming.

[0074] The composite fibers obtained in step four are opened, laid into a web, and bonded with hot air to form a hot-air nonwoven fabric, which is the surface layer of the diaper. The basis weight of the hot-air nonwoven fabric is controlled at 25 g / m². 2 .

[0075] The temperature for hot air bonding is 250℃~280℃. During the hot air bonding process, the PE single layer softens under heat and forms an adhesive at the fiber intersection, while the PET rigid core layer maintains its supporting shape, thus giving the diaper surface layer both fluffiness, softness, and structural stability.

[0076] Step 6: Test the performance of the diaper's surface layer.

[0077] When bacteria, fungi, viruses, and urea-decomposing bacteria in excrement come into contact with the diaper surface layer provided in this embodiment, the non-leaching physical action formed by components such as nanoporous hexagonal boron nitride, few-layer molybdenum disulfide nanosheets, nano-zirconia, and hydrophobic nano-silica achieves contact antibacterial, antiviral, and ammonia-suppressing effects. The specific principle is as follows:

[0078] In some embodiments, the composite fiber has a fineness of 0.8 dtex to 2.0 dtex. The smaller the fineness, the finer the monofilament, and the larger the specific surface area per unit mass of fiber, significantly increasing the effective contact area with bacteria and viruses, thereby enhancing the overall antibacterial and antiviral efficacy. Furthermore, the specific surface area of ​​fibers at this fineness is 3 to 5 times that of conventional sanitary material fibers, ensuring both highly efficient antibacterial and antiviral performance and the soft, skin-friendly properties of the surface layer fibers.

[0079] This embodiment maintains a high degree of consistency in the fineness of the prepared composite fibers through the following process:

[0080] 1) The spinneret adopts a cross-shaped irregular cross-section structure, which increases the specific surface area by 20% to 50% compared with the circular cross-section fiber under the same fineness conditions;

[0081] 2) The spinning draw ratio is controlled between 150 and 250, and the fineness of the monofilament is precisely controlled by a stable draw ratio;

[0082] 3) The side-blowing temperature is controlled at 26-30℃ and the wind speed is controlled at 0.4-0.6m / s to ensure uniform cooling, consistent wire diameter, and eliminate fluctuations in specific surface area;

[0083] In this embodiment, before mass production of core-sheath spinning, composite fiber samples are prepared and their specific surface area is measured. The addition ratio of non-leaching physical antibacterial masterbatch is adjusted based on the specific surface area; the larger the specific surface area, the greater the addition ratio of physical antibacterial masterbatch. The specific surface area range is 1.8 μm. 2 At a concentration of / g, the addition ratio of physical antibacterial masterbatch is 4.2%; the specific surface area range is 2.0m². 2 At a concentration of / g, the addition ratio of physical antibacterial masterbatch is 4.6%; the specific surface area range is 2.2m². 2 When the content is / g, the addition ratio of physical antibacterial masterbatch is 5.0%.

[0084] I. Antibacterial and antiviral principle

[0085] This embodiment involves directionally loading a non-leaching physical antibacterial masterbatch onto the outer layer of composite fibers, allowing the nanocomposite antibacterial powder to be concentrated in the area of ​​the diaper surface that directly contacts the infant's skin, urine, and feces. The nanoporous hexagonal boron nitride in the nanocomposite antibacterial powder possesses a porous, layered structure and a large specific surface area, enabling it to adsorb and accumulate bacteria, fungi, viruses, and their metabolites, increasing the probability of contact between microorganisms and antibacterial functional sites. The few-layered molybdenum disulfide nanosheets and layered nanoporous hexagonal boron nitride have nanoscale layer edges, which can physically disturb bacterial cell walls, cell membranes, fungal cell walls, and viral capsids or envelopes, reducing their structural integrity. Nano-zirconia helps improve the structural stability and processing stability of the nanocomposite antibacterial powder. Hydrophobic nano-silica helps improve the powder dispersion and surface dryness, reducing conditions for the continuous reproduction of microorganisms in humid environments.

[0086] The aforementioned effects do not rely on the outward release of silver ions, zinc ions, copper ions, or organic antibacterial molecules, but rather on the direct contact between the nanocomposite antibacterial powder immobilized in the PE monolayer and bacteria, fungi, and viruses. Upon contact with the surface layer, bacteria and fungi experience physical damage or interference to their cell walls, cell membranes, and membrane-associated enzyme systems, leading to obstruction of nutrient exchange, energy metabolism, and reproductive processes. Similarly, upon contact with the surface layer, viral particles experience adsorption, retention, and physical disturbance of their outer shell, envelope, or surface protein structures, resulting in reduced or inactivated viral infectivity.

[0087] Because the non-leaching physical antibacterial masterbatch is distributed only in the PE single layer and does not penetrate the rigid PET core layer, the antibacterial and antiviral functional components can be concentrated in the effective contact area of ​​the diaper surface layer. This directional loading structure improves the contact efficiency between the functional components and urine, feces, and pathogenic microorganisms therein, avoiding ineffective consumption caused by antibacterial ingredients being buried deep inside the fibers or core layer. At the same time, the non-leaching fixation structure reduces the risk of migration, precipitation, sensitization, and long-term degradation of antibacterial components, allowing the diaper surface layer to maintain contact antibacterial and antiviral capabilities under wet, semi-dry, and dry conditions.

[0088] II. Ammonia Suppression Principle

[0089] (1) Inhibits the activity of urea-decomposing bacteria.

[0090] Urea in infant urine decomposes into ammonia under the action of urea-decomposing bacteria. The continuous irritation of ammonia to infant skin is a major chemical cause of diaper rash. The non-leaching physical antibacterial masterbatch in this embodiment can inhibit the survival and reproduction of urea-decomposing bacteria and other microorganisms, reducing the biological process of urea conversion to ammonia at its source.

[0091] (2) Reduce local metabolic ammonia production caused by bacterial proliferation.

[0092] When microorganisms in feces and the perianal environment proliferate in large numbers in a humid and hot environment, they accelerate urea decomposition and the production of odorous metabolites. This embodiment reduces the microbial load in the surface area through contact antibacterial action, thereby reducing the number of local ammonia-producing microorganisms and decreasing the continuous generation of ammonia.

[0093] (3) The porous structure adsorbs ammonia or ammonia-containing metabolites.

[0094] Nanoporous hexagonal boron nitride and hydrophobic nano-silica possess porous structure, high specific surface area, and surface adsorption capacity, enabling them to adsorb and retain ammonia, water vapor, or ammonia-containing metabolites in certain areas. This effect can reduce the ammonia concentration near the diaper's surface layer, thus minimizing direct skin irritation from ammonia.

[0095] (4) Improve dryness and reduce the ammonia production environment.

[0096] Hydrophobic nano-silica and few-layer molybdenum disulfide nanosheets help improve the dryness and low-friction properties of the fiber surface, reducing urine retention on the surface layer. Reduced local moisture levels inhibit microbial growth and urea decomposition, further reducing ammonia production.

[0097] The antibacterial, antiviral, and ammonia-inhibiting properties of the diaper surface layer prepared in this embodiment were tested as follows:

[0098] (1) Antibacterial performance test

[0099] The skin-friendly, antibacterial, and ammonia-inhibiting diaper surface layer prepared in Example 1 was used as the antibacterial test sample. The test bacteria included Escherichia coli, Staphylococcus aureus, Candida albicans, and Gardnerella vaginalis.

[0100] During testing, sterilized samples were cut to specified sizes and brought into contact with bacterial solutions containing the target bacterial strains. Following the provisions of Clauses E.6.3 and E.6.6 of GB 15979-2024 "Hygienic Standard for Disposable Sanitary Products," a contact antimicrobial evaluation method was used. After contact, the sample eluent was serially diluted, inoculated, cultured, and colony-counted. The colony count was compared with that of the blank control sample to calculate the sterilization rate. The tested bacterial strains included: *Escherichia coli*, *Staphylococcus aureus*, and *Candida albicans*. Standard test conditions: constant temperature 37℃, bacterial solution contact for 1 hour. Test results showed that the functional fibers prepared in this invention exhibited antibacterial and antiviral rates greater than 99% against the tested bacterial strains.

[0101] The above results indicate that the non-leaching physical antibacterial masterbatch in Example 1, after being directionally loaded onto the PE single layer, can form effective antibacterial sites in the contact area of ​​the diaper surface layer, and has a strong inhibitory or killing effect on common bacteria and fungi in urine and feces.

[0102] (2) Virus killing performance test

[0103] The skin-friendly, antibacterial, and ammonia-inhibiting diaper surface layer prepared in Example 1 was used as a sample for testing its antiviral performance. The tested viruses included rotavirus and norovirus (a norovirus surrogate model).

[0104] During testing, the virus suspension was contacted with the sample and reacted for 1 hour under specified temperature and humidity conditions. After the reaction, virus particles on the sample surface were eluted. Virus infection titer determination was used as the primary evaluation method, and viral nucleic acid residue determination was used as an auxiliary evaluation method. The viral activity in the test sample and the blank control sample was compared, and the virus inactivation rate was calculated. The test results showed that the skin-friendly antibacterial and ammonia-inhibiting diaper surface layer prepared in Example 1 had an inactivation rate of greater than 99.9% against rotavirus and greater than 99.9% against norovirus.

[0105] The above results indicate that the diaper surface layer prepared in Example 1 can effectively inactivate fecal-associated viruses, which helps reduce the risk of fecal pathogen transmission in infants and young children during diarrhea.

[0106] (3) Ammonia suppression performance test

[0107] The skin-friendly antibacterial and ammonia-inhibiting diaper surface layer prepared in Example 1 was used as the test sample, and the ordinary diaper surface layer without non-leaching physical antibacterial masterbatch was used as the control sample.

[0108] During testing, equal volumes of simulated urine or urea-containing simulated excretion were added to the test sample and control sample, respectively. A urea-decomposing microbial system was then inoculated or introduced, and the samples were placed in a sealed environment under specified temperature conditions. After a specified time, the ammonia concentration in the sealed space or the change in ammonia nitrogen content in the sample system was measured. The ammonia blocking rate was calculated based on the ammonia release from the control sample and the test sample. Test results showed that the ammonia blocking rate of the skin-friendly, antibacterial, and ammonia-inhibiting diaper surface layer prepared in Example 1 was 99.3%.

[0109] The above results indicate that the non-leaching physical antibacterial masterbatch in Example 1 can reduce the ammonia produced by urine decomposition by inhibiting the activity of urea-decomposing bacteria, reducing microbial reproduction, and adsorbing or blocking the release of ammonia-containing metabolites, thereby reducing the irritation of ammonia to the skin of infants.

[0110] (4) Dissolution performance test

[0111] The skin-friendly antibacterial and ammonia-inhibiting diaper surface layer prepared in Example 1 was used as a test sample. Migration and precipitation tests were carried out according to the standard "GB4806.10-2016". The extraction test results showed that no functional powders and additives migrated and precipitated, the material is safe and non-toxic, has no migration risk, and meets the safety standards for intimate hygiene products.

[0112] The above results indicate that non-leaching physical antibacterial masterbatch can be stably embedded in the PE single layer and achieve antibacterial and antiviral effects without relying on the migration and release of antibacterial ions, small organic molecules or heavy metal components.

[0113] (5) Softness test

[0114] The skin-friendly, antibacterial, and ammonia-inhibiting diaper surface layer prepared in Example 1 was used as a test sample. The sample was cut to a specified size, and the softness level was evaluated. The test results showed that the softness level of the skin-friendly, antibacterial, and ammonia-inhibiting diaper surface layer prepared in Example 1 was 5.

[0115] The above results indicate that when PE single-layer ES composite fiber is combined with PET rigid core layer, it can still achieve high softness while maintaining the stability of the surface layer structure.

[0116] (6) Stability test of spinning process

[0117] Continuous production process conditions: spinning temperature 280~300℃, spinning speed 3000m / min. Continuous 72h uninterrupted spinning verification: the spinning process was stable, with no fiber breakage or web blockage. Finished fiber specifications: breaking strength ≥2.5cN / dtex, fineness CV value ≤5%, meeting the industrial production and use standards for sanitary napkin surface layer fibers.

[0118] Example 2

[0119] A skin-friendly, antibacterial, and ammonia-inhibiting diaper surface layer, specially formulated for sensitive skin. Except for the following differences, this embodiment is identical to Embodiment 1 in all other aspects: structural composition, composition of the non-leaching physical antibacterial masterbatch, composition of the nanocomposite antibacterial powder, masterbatch granulation method, composite fiber structure, antibacterial masterbatch directional loading method, and hot-air nonwoven fabric molding method.

[0120] The difference between this embodiment and Embodiment 1 is that the amount of non-leaching physical antibacterial masterbatch used is different relative to the mass fraction of polyethylene masterbatch, and the specific surface area of ​​the composite fiber is different.

[0121] In Example 1, the amount of non-leaching physical antibacterial masterbatch relative to the mass fraction of polyethylene masterbatch was 4.6%; the specific surface area of ​​the composite fiber was 2.0 m². 2 / g.

[0122] In this embodiment, the amount of non-leaching physical antibacterial masterbatch relative to the mass fraction of polyethylene masterbatch is 5.0%; the specific surface area of ​​the composite fiber is 2.2 m². 2 / g. In this embodiment, based on 500 parts by weight of polyethylene masterbatch, the amount of non-leaching physical antibacterial masterbatch is adjusted from 23 parts in Example 1 to 25 parts. 500 parts of polyethylene masterbatch, 25 parts of non-leaching physical antibacterial masterbatch, and an appropriate amount of spinning aid are added to the extrusion section of the PE single-layer to form the PE single-layer melt; 900 parts of polyethylene terephthalate masterbatch are added to the extrusion section of the PET rigid core to form the PET rigid core melt. No non-leaching physical antibacterial masterbatch is added to the PET rigid core.

[0123] In this embodiment, the steps for forming PE single-layer ES composite fibers through composite spinning are basically the same as in Example 1, except that the spinning temperature of the PE single-layer is controlled at 240°C and the melt pressure is controlled at 14MPa; the spinning temperature of the PET rigid core layer is still controlled at 280°C to 290°C. After extrusion by the composite spinning assembly, composite fibers are formed. The non-leaching physical antibacterial masterbatch is only distributed in the PE single-layer, and the PET rigid core layer does not contain the non-leaching physical antibacterial masterbatch.

[0124] Compared with Example 1, the specific surface area of ​​the composite fiber in this example is further increased. At the same time, this example increases the proportion of non-leaching physical antibacterial masterbatch added based on the increased specific surface area of ​​PE single-layer fiber, so that the surface of the fiber with higher specific surface area has a more sufficient distribution of non-leaching physical antibacterial sites, thereby further improving the antifungal and antiammonia properties of the diaper surface layer, making it more suitable for use in scenarios involving sensitive skin or infants with diarrhea.

[0125] Example 3

[0126] A skin-friendly, antibacterial, and ammonia-inhibiting diaper surface layer is described in this embodiment, which differs from Embodiment 1 in that: the specific surface area of ​​the composite fibers is different; and the mass fraction of the non-leaching physical antibacterial masterbatch relative to the polyethylene masterbatch is different. In this embodiment, the specific surface area of ​​the composite fibers is 1.8 m². 2 / g; the amount of non-leaching physical antibacterial masterbatch is 4.2% of the mass fraction of polyethylene masterbatch. In this embodiment, the specific surface area of ​​the composite fiber is reduced compared with Example 1, and the addition ratio of non-leaching physical antibacterial masterbatch is reduced accordingly to avoid excessive addition causing fiber pore blockage, hardening of the surface layer or reduction of air permeability.

[0127] Example 4

[0128] like Figure 3 As shown, a diaper with a skin-friendly, antibacterial, and ammonia-inhibiting diaper surface layer includes a diaper body and an elastic waistband 5. The skin-friendly surface layer 1 is the skin-friendly, antibacterial, and ammonia-inhibiting diaper surface layer provided in Example 1, Example 2, or Example 3.

[0129] The diaper body comprises, in order from the inside out (i.e., from the side closest to the skin to the side furthest from the skin), a skin-friendly surface layer 1, a diversion layer 2, an absorbent core 3, and a breathable bottom layer 4. The skin-friendly surface layer 1 is located closest to the infant's skin and is in direct contact with the infant's skin, urine, and feces. The diversion layer 2 is positioned between the skin-friendly surface layer 1 and the absorbent core 3, guiding urine that has passed through the skin-friendly surface layer 1 along the length and thickness of the diaper into the absorbent core 3. The absorbent core 3 absorbs and retains urine. The breathable bottom layer 4 is located on the side of the absorbent core 3 furthest from the skin-friendly surface layer 1, preventing liquid leakage while allowing moisture to pass through. The elastic waistband 5 is located at the waist opening of the diaper body to improve the fit around the waist.

[0130] In this embodiment, the flow guiding layer 2 can be made of hydrophilic nonwoven fabric or fiber layer with flow guiding pores to improve the urine diffusion rate; the absorbent core 3 can be made of a composite absorbent structure formed by superabsorbent polymer and fluff pulp; the breathable bottom layer 4 can be made of a composite structure of breathable waterproof membrane and outer nonwoven fabric; the anti-leakage guard 7 can include guard nonwoven fabric and elastic element extending along the length direction.

[0131] In some embodiments, the waistband structure of the diaper body adopts a segmented structure, including a front waistband and a back waistband. Both ends of the back waistband are provided with adhesive components 6. The adhesive components 6 can be attached to the front waistband. The adhesive components 6 are used to secure the two ends of the front waistband and the two ends of the back waistband together during wear. The segmented structure of the diaper body improves the ease of wearing.

[0132] In some embodiments, the diaper body is provided with side leakage protection 7 on both sides to reduce the risk of urine or loose stool leaking from the sides of the diaper.

[0133] The diapers provided in this embodiment are prepared according to the following steps.

[0134] Step 1: Prepare the skin-friendly surface layer 1.

[0135] The skin-friendly surface layer 1 was prepared according to the preparation method provided in Example 1, Example 2 or Example 3.

[0136] Step 2: Prepare the other components of the diaper.

[0137] Prepare the following components: 2. Drainage layer; 3. Absorbent core; 4. Breathable bottom layer; 7. Anti-leakage guard; 5. Elastic waistband; and 6. Adhesive components.

[0138] Step 3: Layered composite.

[0139] The skin-friendly surface layer 1 is laid on the inner side of the diversion layer 2, the diversion layer 2 is laid on the inner side of the absorbent core 3, and the breathable bottom layer 4 is laid on the outer side of the absorbent core 3, so that the skin-friendly surface layer 1, the diversion layer 2, the absorbent core 3 and the breathable bottom layer 4 form a layered structure arranged sequentially from the inside to the outside. The skin-friendly surface layer 1, the diversion layer 2, the absorbent core 3 and the breathable bottom layer 4 are fixed together by edge heat pressing to obtain the main body of the diaper.

[0140] Step 4: Install the anti-leakage guardrail 7.

[0141] The anti-leakage guard 7 is heat-pressed onto both sides of the diaper body.

[0142] Step 5: Install the elastic waistband 5 and attach the components 6.

[0143] Secure the elastic waistband 5 to the waist opening of the diaper body.

[0144] Step 6: Finished product shaping.

[0145] The composite diapers are pressed, cut, and packaged to obtain the finished diapers.

[0146] In this embodiment, the skin-friendly surface layer 1 is used as a direct contact layer. When urine or feces first come into contact with the skin-friendly surface layer 1, the non-leaching physical antibacterial masterbatch in the PE monolayer can come into contact with microorganisms. Since the non-leaching physical antibacterial masterbatch is distributed in the PE monolayer and the PE monolayer is located on the surface of the composite fiber, the antibacterial functional components can be close to the excrement contact interface, thereby improving the antibacterial, antifungal, antiviral, and ammonia-suppressing efficiency.

[0147] In this embodiment, the PE single-layer of the skin-friendly surface layer 1 provides a soft and skin-friendly contact surface, helping to reduce friction irritation; the rigid PET core layer improves the support and fluffiness stability of the surface layer fibers, helping to maintain the surface layer's spatial structure; the non-leaching physical antibacterial masterbatch achieves antibacterial and antiviral effects through nano-physical contact, porous adsorption, and disruption of microbial membrane structures; simultaneously, it inhibits ammonia at the source by suppressing the activity of urea-decomposing bacteria and reducing ammonia accumulation. Therefore, the diaper can further improve its skin-friendliness, antibacterial safety, and diaper rash prevention performance while maintaining its absorption, leak-proof, and secure fit functions.

Claims

1. A skin-friendly antibacterial and ammonia-inhibiting diaper topsheet formed by composite fibers; the composite fibers comprising a core layer and a skin layer coated on the outside of the core layer; characterized in that, The outer layer is formed by melt spinning polyethylene masterbatch and non-leaching physical antibacterial masterbatch; the core layer is formed by melt spinning polyethylene terephthalate masterbatch. The non-leaching physical antibacterial masterbatch includes a polyethylene carrier and nanocomposite antibacterial powder dispersed in the polyethylene carrier; the nanocomposite antibacterial powder includes nanoporous hexagonal boron nitride, molybdenum disulfide nanosheets, nanozirconium oxide and hydrophobic nano silica.

2. The skin-friendly antibacterial and ammonia-inhibiting diaper topsheet according to claim 1, characterized in that, In the nanocomposite antibacterial powder, the mass fraction of nanoporous hexagonal boron nitride is 70wt% to 85wt%; the mass fraction of molybdenum disulfide nanosheets is 8wt% to 18wt%; the mass fraction of nanozirconium oxide is 3wt% to 10wt%; and the mass fraction of hydrophobic nano silica is 2wt% to 8wt%.

3. The skin-friendly antibacterial and ammonia-inhibiting diaper topsheet according to claim 1, characterized in that, The non-leaching physical antibacterial masterbatch comprises, by weight percentage: 15wt%–35wt% nanocomposite antibacterial powder, 55wt%–80wt% polyethylene carrier, 1wt%–5wt% silane coupling agent, and 1wt%–5wt% high-temperature resistant lubricant.

4. The skin-friendly antibacterial and ammonia-inhibiting diaper topsheet according to claim 1, characterized in that, In the raw materials used to form the skin layer, the mass ratio of non-leaching physical antibacterial masterbatch to polyethylene masterbatch is (4-5.5):

100.

5. The skin-friendly antibacterial and ammonia-inhibiting diaper topsheet according to claim 4, characterized in that, The composite fiber has a fineness of 0.8 dtex to 2.0 dtex; the specific surface area of the composite fiber is 1.8 m 2 / g to 2.2 m 2 / g; the mass ratio of the non-dissolution physical antibacterial masterbatch in the skin layer to the polyethylene carrier increases with the increase of the specific surface area of the composite fiber.

6. A method of manufacture characterised by, The preparation method comprises: [The method is used to prepare the skin-friendly, antibacterial, and ammonia-inhibiting diaper surface layer as described in claim 1;] A nanocomposite antibacterial powder was obtained by mixing nanoporous hexagonal boron nitride, molybdenum disulfide nanosheets, nanozirconium oxide, and hydrophobic nano silica. The nanocomposite antibacterial powder is mixed with a polyethylene carrier and melt-granulated to obtain a non-leaching physical antibacterial masterbatch. Polyethylene masterbatch is melt-mixed with non-leaching physical antibacterial masterbatch to form a skin-layer composite melt; The polyethylene terephthalate masterbatch is melted to form the core layer melt; Composite spinning is performed using a sheath-core composite melt and a core melt to obtain composite fibers with a sheath-core structure. The composite fibers are processed into nonwoven fabric to obtain the skin-friendly, antibacterial, and ammonia-inhibiting diaper surface layer.

7. The production method according to claim 6, wherein In preparing the non-leaching physical antibacterial masterbatch, the nanocomposite antibacterial powder, polyethylene carrier, silane coupling agent and high-temperature lubricant are mixed and then melt-blended and extruded into granules.

8. The preparation method according to claim 6, characterized in that, During the composite spinning process, the spinning temperature of the outer layer is 230℃~250℃, and the spinning temperature of the core layer is 280℃~290℃; the nonwoven fabric forming process includes opening, web laying and hot air bonding; the temperature of the hot air bonding is 250℃~280℃.

9. The preparation method according to claim 6, characterized in that, During the composite spinning process, the sheath composite melt and the core melt respectively enter the composite spinning assembly. The sheath composite melt covers the outside of the core melt in the composite spinning assembly and forms a composite fiber with a sheath-core structure after being spun into fibers.

10. A paper diaper comprising a paper diaper main body, the paper diaper main body comprising, in order from the inside out, a skin-friendly surface layer, a flow guide layer, an absorbent core body, and a breathable bottom layer; characterized in that, The skin-friendly surface layer is the skin-friendly, antibacterial, and ammonia-inhibiting diaper surface layer as described in any one of claims 1 to 5.

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