High-water-absorption paper diaper and preparation process thereof

Abstract

The invention relates to the technical field of paper diapers, in particular to a high-water-absorption paper diaper and a preparation process thereof.The high-water-absorption paper diaper comprises a skin-friendly layer, a core layer, an impermeable layer and a liquid-leakage-free bottom layer, a three-layer gradient flow guide structure is arranged between the skin-friendly layer and the core layer, and the three-layer gradient flow guide structure is formed by overlapping a first flow guide layer, a second flow guide layer and a third flow guide layer from top to bottom; the first flow guide layer is a non-woven fabric layer containing fluff pulp, the second flow guide layer is a three-dimensional embossed non-woven fabric layer, and the third flow guide layer is a directional flow guide surface layer. The pressure difference from the surface layer to the inner layer is formed through material configuration and surface treatment of the third flow guide layer and becomes driving force for continuous downward movement of the liquid, and the absorbed liquid is prevented from reversely permeating to the surface layer.

Description

Technical Field

[0001] This invention relates to the field of diaper technology, specifically to a highly absorbent diaper and its manufacturing process. Background Technology

[0002] Disposable diapers have become an essential part of modern life, especially for infant care. With the improvement of overall living standards and the continuous development of science and technology, the market's requirements for the comprehensive performance of these products are becoming increasingly stringent and diversified. Users' expectations for diapers go beyond basic protective functions; they pay close attention to their superior performance in core performance indicators such as absorbency, breathability, wearing comfort, and safety. Among these important performance dimensions, absorbency is undoubtedly the core element in determining whether a diaper can be widely accepted by users. It directly determines whether the diaper can quickly and effectively absorb and lock in liquid, thereby keeping the user's skin dry and reducing discomfort or even skin problems.

[0003] Existing disposable diapers mostly use superabsorbent polymers as absorbent materials, but their cost is relatively high and there is still room for improvement in absorption rate and water retention capacity.

[0004] Therefore, we propose a highly absorbent diaper and its manufacturing process. Summary of the Invention

[0005] One of the technical problems this application aims to solve is that: the production cost of superabsorbent polymers is relatively high; there is still room for improvement in the initial absorption rate when dealing with a large amount of liquid influx; there is also room for further optimization in terms of the water-locking or water-retention capacity after absorbing liquid; and the design concept of the existing diaper core layer structure is relatively simple or homogeneous, failing to fully consider the differences in pressure conditions in different areas and the problem of maximizing the longitudinal and lateral diffusion efficiency of liquid in the core.

[0006] To solve the above technical problems, this application provides a highly absorbent diaper, including a skin-friendly layer, a core layer, a leak-proof layer and a leak-proof bottom layer. A three-layer gradient flow-guiding structure is provided between the skin-friendly layer and the core layer. The three-layer gradient flow-guiding structure is composed of a first flow-guiding layer, a second flow-guiding layer and a third flow-guiding layer stacked from top to bottom. The first flow guiding layer is a non-woven fabric layer containing fluff pulp, the second flow guiding layer is a three-dimensional embossed non-woven fabric layer, and the third flow guiding layer is a directional flow guiding surface layer, which is woven from fibers formed by a surface layer covered with hydrophobic material.

[0007] In some embodiments, the core layer includes an upper core, a middle core, and a lower core disposed from top to bottom; The upper core is a nonwoven fabric matrix uniformly dispersed with a mixed water-absorbing material, which consists of 25-30 wt% starch-based polyether polyol modified wood fiber, 10-15 wt% cellulose nanofiber and 55-65 wt% superabsorbent polymer; the middle core is a nonwoven fabric layer with a mixed distribution of superabsorbent polymer with dual particle sizes of 150-200 μm and 320-400 μm; the lower core has independent storage areas at the front, middle and rear, and each storage area is filled with superabsorbent polymer with a particle size of 350-450 μm.

[0008] In some embodiments, the seepage-proof layer is a breathable seepage-proof membrane, the leak-proof bottom layer is made of a breathable microporous membrane and a tensile nonwoven fabric bonded together with hot melt adhesive, and the inner side of the diaper is also provided with a three-dimensional leak-proof partition.

[0009] In some embodiments, a process for manufacturing highly absorbent diapers includes the following steps: S1: Prepare the flow-guiding layer component by weaving the third flow-guiding layer fiber using a two-component spunbond method and depositing a hydrophobic layer on the surface of the fiber using a spraying technique. S2: Assemble the three-layer flow-guiding structure by sequentially hot-pressing the non-woven fabric impregnated with fluff pulp, the three-dimensional embossed non-woven fabric, and the surface-modified third flow-guiding layer. S3: Construct a layered core. The upper core uses airflow web forming technology to uniformly disperse modified wood fibers, nanocellulose and superabsorbent polymers on the nonwoven fabric substrate. The middle core is laid on a non-woven fabric carrier by gradient distribution of dual-particle-size superabsorbent polymers through oscillating sieving. The lower core uses a zoned positioning spray adhesive technology to form a storage area on the non-woven fabric substrate and fill it with large-particle resin.

[0010] In some embodiments, the hydrophobic layer in S1 is coated with a fluoropolymer solution and then cured at 85-95°C for 30-45 seconds.

[0011] In some embodiments, the mixing pressure of each component in the upper core of S3 is 0.15-0.25 MPa, and the airflow velocity is 8-12 m / s.

[0012] In some embodiments, the boundary of the lower core storage area is formed by ultrasonic welding to create a resin barrier dam.

[0013] In some embodiments, an embossing process is also included to apply longitudinal drainage grooves between the core layer and the impermeable layer.

[0014] This invention has at least the following beneficial effects: 1. By setting a three-layer gradient flow-guiding structure between the skin-friendly layer and the core layer, the liquid can be rapidly and evenly diffused on the surface and efficiently guided downward to the core absorption area. This alleviates the common problem of local oversaturation in the initial stage of liquid entry, allowing the liquid to be absorbed and utilized by a larger area of ​​the core layer material, significantly improving the initial liquid absorption rate and overall absorption capacity.

[0015] 2. The material configuration and surface treatment of the third diversion layer create a pressure difference from the surface to the inner layer, driving the continuous downward movement of the liquid. Simultaneously, combined with the powerful capillary pull generated by the smaller structures at the bottom of the core layer, this collective action greatly promotes the rapid penetration and locking of liquid into the deeper layers of the diaper. This effectively reduces the tendency for absorbed liquid to seep back to the surface, significantly improving the diaper's absorbency and ensuring that the wearer's skin remains dry and comfortable for a longer period.

[0016] 3. The core employs a layered and zoned design. The upper layer is a composite material made of modified wood fibers, cellulose nanofibers, and superabsorbent polymers in a specific ratio. This combination not only provides excellent initial absorption rate but also offers good structural support. The middle layer optimizes the particle packing structure by mixing superabsorbent polymer particles of different diameters, forming a more compact and effective absorbent network space. This significantly improves the utilization rate of the core material and the overall absorption and locking efficiency of liquids. The lower layer features specially designed storage units located in different functional areas. These units can specifically absorb and lock in liquids flowing towards high-load areas such as the waist and abdomen, enhancing regional protection capabilities, regardless of the baby's different activity postures. Through these layered functional optimizations, the entire core layer achieves a comprehensive improvement in absorption speed, total absorption capacity, and long-term water-locking performance.

[0017] 4. This diaper not only prioritizes absorbency but also ensures comfort. The specially selected composite structure and materials achieve high absorbency and prevent backflow while maintaining excellent overall breathability, avoiding the problem of stuffiness and discomfort caused by increased absorbency. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the layering of the diaper of the present invention; Figure 2 This is a schematic diagram of the three-layer gradient flow guiding structure of the present invention; Figure 3 This is a schematic diagram of the core layer of the present invention; Figure 4 This is a schematic diagram of the production process of the present invention.

[0019] In the diagram, 100 - skin-friendly layer; 200 - core layer; 201 - upper core; 202 - middle core; 203 - lower core; 2031 - storage area; 300 - impermeable layer; 400 - leak-proof bottom layer; 500 - three-layer gradient flow guiding structure; 501 - first flow guiding layer; 502 - second flow guiding layer; 503 - third flow guiding layer. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] See Figure 1-3 The present invention provides a technical solution: a highly absorbent diaper, comprising a skin-friendly layer 100, a core layer 200, a leak-proof layer 300, and a leak-proof bottom layer 400, wherein a three-layer gradient flow guiding structure 500 is provided between the skin-friendly layer 100 and the core layer 200, and the three-layer gradient flow guiding structure 500 is composed of a first flow guiding layer 501, a second flow guiding layer 502, and a third flow guiding layer 503 stacked from top to bottom; The first flow guiding layer 501 is a non-woven fabric layer containing fluff pulp, the second flow guiding layer 502 is a three-dimensional embossed non-woven fabric layer, and the third flow guiding layer 503 is a directional flow guiding surface layer.

[0022] The core layer 200 includes an upper core 201, a middle core 202, and a lower core 203 arranged from top to bottom. The upper core 201 is a nonwoven fabric matrix uniformly dispersed with a mixed water-absorbing material, which is composed of 25-30 wt% starch-based polyether polyol modified wood fiber, 10-15 wt% cellulose nanofiber, and 55-65 wt% superabsorbent polymer. The middle core 202 is a nonwoven fabric layer mixed with superabsorbent polymer with dual particle sizes of 150-200 μm and 320-400 μm. The lower core 203 has independent storage areas 2031 at the front, middle, and rear, and each storage area 2031 is filled with superabsorbent polymer with a particle size of 350-450 μm.

[0023] Specifically, a three-layer gradient flow guiding structure 500 is placed between the skin-friendly layer 100 and the core layer 200 to form a flow guiding system. Its design principle and purpose are specifically reflected in the following aspects: The first flow guiding layer 501 uses a nonwoven fabric containing fluff pulp, which has a gentle contact and initial dispersion function. When liquid passes through the skin-friendly layer 100 and reaches this layer, the multi-dimensional network structure formed by the fluff pulp fibers can buffer the impact intensity of the flow and expand the lateral diffusion range of the liquid to avoid concentrated seepage. The second flow guiding layer 502 has a unique three-dimensional embossed nonwoven fabric as its core structure. The three-dimensional grooves and protrusions pressed on its surface constitute a physical flow guiding channel network. This network actively guides the liquid flow along a preset path, significantly improving the directional liquid transmission efficiency and effectively solving the problem of uneven flow in traditional planar laminar flow. The third flow guiding layer 503 acts as the driving core to implement a directional flow guiding mechanism. When liquid contacts the upper surface of this layer, it can only wet and diffuse along the longitudinal direction of the fibers and is difficult to penetrate laterally.

[0024] The three-layer structure creates a gradient surface tension difference. The interfacial tension gradually decreases from the first guide layer 501 to the third guide layer 503, forming a capillary pressure gradient that provides the liquid with a continuous downward driving force. The difference between the ultra-low surface energy of the upper surface and the high surface energy of the lower surface of the third guide layer 503 creates a significant wetting pressure difference, which prompts the liquid to penetrate the fiber interface layer and rapidly transfer to the core layer 200. The three-dimensional channel structure of the second guide layer 502 effectively avoids the formation of local turbulence or stagnation areas during the transfer process. The double hydrophobic mechanism of the third guide layer 503 creates a liquid migration barrier. The hydrophobic coating of the fibers and the surface hydrophobic coating together generate surface wetting resistance, forcing the liquid to migrate downwards only through the fiber gaps.

[0025] The seepage-proof layer 300 is a breathable seepage-proof membrane, and the leak-proof bottom layer 400 is made of a breathable microporous membrane and a tensile non-woven fabric bonded together with hot melt adhesive. The inside of the diaper is also equipped with a three-dimensional leak-proof partition.

[0026] The preparation process of starch-based polyether polyol modified wood fiber is as follows: The raw material ratio by weight percentage is as follows: 55% softwood pulp fiber; 20% cassava starch; 15% polyether polyol (PPG-2000); 5% maleic anhydride; 2% potassium persulfate; and 3% borax.

[0027] Stepwise preparation process: Step 1: Fiber pretreatment. Softwood pulp fibers (1.2-1.8 mm in length) are immersed in an 8% (w / w) NaOH solution and treated at 80°C for 45 minutes. After washing with water until neutral, the fibers are pulverized and passed through a 120-mesh sieve to obtain a specific surface area > 8.5 m². 2 / g of microfibrillated cellulose.

[0028] Step 2: Starch plasticization. Tapioca starch and borax are mixed in a ratio of 100:12. Deionized water is added to adjust the solid content to 30%. The mixture is gelatinized at 85°C for 30 minutes to form a transparent colloid. Polyether polyol (PPG-2000) is added and emulsified at 110°C under high-speed shear (12000 rpm, 10 minutes) to obtain starch-polyether composite melt (dynamic viscoelasticity: G' = 1250 Pa, G" = 980 Pa).

[0029] Step 3: Mechanochemical modification. Pretreated fiber, starch-polyether melt, maleic anhydride, and potassium persulfate were added to a high-temperature ball mill jar (zirconia balls Φ3mm, ball-to-material ratio 10:1). The reaction was carried out at 135℃ for 2.5 hours under nitrogen protection. The parameters were: ball milling speed 250rpm (centrifugal acceleration 12g); reaction pressure 0.35MPa; and the reaction was terminated when the carboxyl content reached 0.85mmol / g, as monitored in real time.

[0030] Step 4: Post-processing. The reaction product is flash-dried with hot air at 80℃, then ground and classified to obtain modified fibers with a particle size of 45-150μm and a bulk density of 0.28g / cm³. 3 Moisture content ≤ 5%.

[0031] A manufacturing process for highly absorbent diapers includes the following steps: S1: Prepare the flow-guiding layer component by weaving the third flow-guiding layer 503 flow-guiding fiber using a two-component spunbonding method, and deposit a hydrophobic layer on the upper surface of the fiber using a spraying technique. S2: Assemble the three-layer flow-guiding structure by sequentially hot-pressing the non-woven fabric impregnated with fluff pulp, the three-dimensional embossed non-woven fabric, and the surface-modified third flow-guiding layer 503. S3: Construct a layered core. The upper core 201 uses airflow web forming technology to uniformly disperse modified wood fiber, nanocellulose and superabsorbent polymer on the nonwoven fabric substrate. The middle core 202 uses oscillating sieving to gradient-lay superabsorbent polymer with dual particle size on the nonwoven fabric carrier. The lower core 203 uses zoned positioning spray adhesive technology to form a storage area 2031 on the nonwoven fabric substrate and fill it with large particle size resin.

[0032] The hydrophobic layer in S1 is coated with a fluoropolymer solution and cured at 85-95℃ for 30-45 seconds after coating. In S3, the mixing pressure of each component in the upper core 201 is 0.15-0.25 MPa, and the airflow velocity is 8-12 m / s. The boundary of the storage area 2031 in the lower core 203 is formed by ultrasonic welding to create a resin barrier dike with a height of 0.8-1.2 mm. An embossing process is applied between the core layer 200 and the impermeable layer 300, creating longitudinal flow channels.

[0033] The preparation process of the fluoropolymer solution is as follows: Raw material composition (by mass percentage): perfluoroalkyl acrylate copolymer 22%; ethylene glycol monobutyl ether 35%; acetone 25%; nano silica dispersion (particle size 30-50nm) 15%; silane coupling agent (KH-570) 2.5%; leveling agent (polyether modified polydimethylsiloxane) 0.5%; Step-by-step preparation process: Step 1: Pre-dispersion. Add the perfluoroalkyl acrylate copolymer to ethylene glycol monobutyl ether and stir at 1200 rpm for 15 minutes in a water bath at 45-50℃ until a transparent viscous liquid is formed.

[0034] Step 2: Nano-modification. Add nano-silica dispersion and silane coupling agent, and transfer to an ultrasonic disperser (power 800W, frequency 28kHz) for 20 minutes to make the nanoparticles uniformly encapsulate the fluorocarbon chain.

[0035] Step 3: Solvent preparation, inject acetone and cool to 25°C, add leveling agent and stir at low speed of 500 rpm for 30 minutes to eliminate bubbles and form a homogeneous system.

[0036] Step 4: Precision filtration. The solution is filtered under pressure through a 0.1μm polytetrafluoroethylene filter membrane to obtain a colorless and transparent solution with a dynamic viscosity controlled at 25-30 mPa·s (25℃).

[0037] Example 1: A highly absorbent diaper comprises a skin-friendly layer 100, a core layer 200, a leak-proof layer 300, and a leak-proof bottom layer 400, wherein a three-layer gradient flow-guiding structure 500 is provided between the skin-friendly layer 100 and the core layer 200. The flow-guiding structure consists of a first flow-guiding layer 501 made of nonwoven fabric containing 15wt% fluff pulp; a second flow-guiding layer 502 made of three-dimensional embossed nonwoven fabric with an embossing depth of 0.4mm; and a third flow-guiding layer 503 woven from bicomponent flow-guiding fibers with a hydrophobic layer thickness of 0.8μm. The core layer 200 includes an upper core 201 containing 25 wt% starch-based polyether polyol modified wood fiber, 10 wt% cellulose nanofiber, and 65 wt% superabsorbent polymer, which are uniformly dispersed by an airflow web forming process (mixing pressure 0.2 MPa, airflow velocity 10 m / s); a middle core 202 using 180 μm and 350 μm dual-particle-size resin laid in a 5:7 volume ratio gradient; and a lower core 203 with three independent storage zones 2031 (accounting for 40% of the total area), filled with 400 μm resin, with the rear filling density being 13% higher than the front.

[0038] The preparation process is as follows: The first step involves the preparation of the flow-guiding structure. The first flow-guiding layer 501 is a base fabric formed by mixing 15wt% fluff pulp with polypropylene fibers and then using a hot air penetration nonwoven fabric process (temperature 110℃, wind speed 8m / s), with a basis weight of 22g / m². 2The second flow guiding layer 502 is subjected to three-dimensional embossing (roller temperature 125℃, pressure 0.8MPa) to form a diamond-shaped protrusion array with a depth of 0.4mm. A fluoropolymer solution (12% solid content) is sprayed onto the surface of the third flow guiding layer 503, resulting in a wet film thickness of 3.8μm; this is then cured with hot air at 90℃ for 40 seconds to form a 0.8μm hydrophobic layer.

[0039] The second step involves assembling the core layer 200. The upper core 201 is formed by feeding modified wood fiber (25 wt%), nanocellulose (12 wt%), and SAP resin (63 wt%) into an air-laid machine; the mixture is uniformly laid out (1.8 mm thickness) under a mixing pressure of 0.2 MPa and an airflow velocity of 10 m / s. The middle core 202 consists of a 5:7 volume ratio gradient of 180 μm and 350 μm resin (70% of the 180 μm resin in the front region and 85% of the 350 μm resin in the rear region). The lower core 203 uses a nonwoven fabric substrate (20 kHz frequency, 45 μm amplitude) to form a 1.0 mm high dam; three storage zones 2031 are filled with 400 μm resin, with the rear density being 13% higher than the front.

[0040] The third step, composite and post-processing, involves sequentially stacking the flow-guiding structure 500, the core layer 200, and the impermeable layer 300 (breathable membrane); followed by hot-pressing composite (temperature 95℃, pressure 0.6MPa, speed 1.5m / min). Cut and shape it, then add elastic waistbands.

[0041] The third guide layer 503 adopts a sprayed hydrophobic layer with a curing temperature of 90℃ / 40 seconds. The boundary of the storage area 2031 is formed by ultrasonic welding to form a 1.0mm barrier dam.

[0042] Example 2: The core layer 200 includes an upper core 201 containing 30 wt% starch-based polyether polyol modified wood fiber, 15 wt% cellulose nanofiber, and 55 wt% superabsorbent polymer, uniformly dispersed by an airflow web forming process (mixing pressure 0.25 MPa, airflow velocity 12 m / s). The rest is the same as in Example 1.

[0043] Example 3: The core layer 200 includes an upper core 201 containing 28 wt% starch-based polyether polyol modified wood fiber, 14 wt% cellulose nanofiber, and 58 wt% superabsorbent polymer, uniformly dispersed by an airflow web forming process (mixing pressure 0.15 MPa, airflow velocity 8 m / s). The rest is the same as in Example 1.

[0044] Comparative Example 1: The starch-based polyether polyol modified wood fiber was replaced with an equal amount of wood fiber, and the rest of the structure was the same as in Example 1.

[0045] Comparative Example 2: The three-layer gradient flow guiding structure only includes a first flow guiding layer of equal thickness, and the rest is the same as in Example 1.

[0046] The test results of Examples 1-3 and Comparative Examples 1-2 are shown in the table below: In Comparative Example 2, after the three-layer gradient flow structure was removed, the penetration time was extended to 3.2 seconds and the lateral diffusion area was reduced by 45%, proving that the multi-layer flow design significantly accelerates liquid penetration and diffusion.

[0047] In Comparative Example 1, the removal of starch-based polyether polyol-modified wood fibers resulted in insufficient water absorption and backflow performance.

Claims

1. A highly absorbent diaper, comprising a skin-friendly layer (100), a core layer (200), a leak-proof layer (300), and a leak-proof bottom layer (400), characterized in that: A three-layer gradient flow guiding structure (500) is provided between the skin-friendly layer (100) and the core layer (200). The three-layer gradient flow guiding structure (500) is composed of a first flow guiding layer (501), a second flow guiding layer (502) and a third flow guiding layer (503) stacked from top to bottom. The first flow guiding layer (501) is a non-woven fabric layer containing fluff pulp, the second flow guiding layer (502) is a three-dimensional embossed non-woven fabric layer, and the third flow guiding layer (503) is a directional flow guiding surface layer, which is woven from fibers formed by a surface layer covered with hydrophobic material.

2. The highly absorbent diaper according to claim 1, characterized in that: The core layer (200) includes an upper core (201), a middle core (202) and a lower core (203) arranged from top to bottom. The upper core (201) is a non-woven fabric matrix uniformly dispersed with a mixed water-absorbing material, which is composed of 25-30wt% starch-based polyether polyol modified wood fiber, 10-15wt% cellulose nanofiber and 55-65wt% superabsorbent polymer. The middle core (202) is a non-woven fabric layer with a mixture of 150-200μm and 320-400μm dual-particle-size superabsorbent polymers. The lower core (203) has independent storage areas (2031) in the front, middle and rear parts, and each storage area (2031) is filled with superabsorbent polymer with a particle size of 350-450μm.

3. The highly absorbent diaper according to claim 1, characterized in that: The seepage-proof layer (300) is a breathable seepage-proof membrane, and the non-leaking bottom layer (400) is made of a breathable microporous membrane and a tensile non-woven fabric bonded together with hot melt adhesive. The inner side of the diaper is also provided with a three-dimensional leak-proof partition.

4. A manufacturing process for highly absorbent diapers according to any one of claims 1-3, characterized in that, Includes the following steps: S1: Prepare the flow guiding layer component by weaving the third flow guiding layer (503) fiber by two-component spunbonding and depositing a hydrophobic layer on the surface of the fiber by spraying technology; S2: Assemble the three-layer flow-guiding structure by sequentially hot-pressing the non-woven fabric impregnated with fluff pulp, the three-dimensional embossed non-woven fabric, and the surface-modified third flow-guiding layer. S3: Construct a layered core, wherein the upper core (201) uses airflow web forming technology to uniformly disperse modified wood fiber, nanocellulose and superabsorbent polymer on a nonwoven fabric substrate; The middle core (202) is laid on the non-woven fabric carrier by a gradient of dual-particle-size superabsorbent polymer through oscillating sieving; The lower core (203) uses a partitioned positioning spray adhesive technology to form the storage area (2031) on the non-woven fabric substrate and fill it with large-particle resin.

5. The manufacturing process for a highly absorbent diaper according to claim 4, characterized in that: The hydrophobic layer in S1 is coated with a fluoropolymer solution and then cured at 85-95°C for 30-45 seconds.

6. The manufacturing process of a highly absorbent diaper according to claim 4, characterized in that: The mixing pressure of each component in the upper core (201) in S3 is 0.15-0.25 MPa, and the airflow velocity is 8-12 m / s.

7. The manufacturing process for a highly absorbent diaper according to claim 4, characterized in that: The boundary of the storage area of ​​the lower core (203) is formed by ultrasonic welding to create a resin barrier dam.

8. The manufacturing process of a highly absorbent diaper according to claim 4, characterized in that: It also includes an embossing process in which a longitudinal guide groove is applied between the core layer (200) and the impermeable layer (300).

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