A multi-layer sanitary napkin fabric capable of directing rapid directional transport of liquid and a method of making the same

Abstract

This invention provides a multi-layer sanitary napkin fabric capable of guiding rapid directional transport of liquid and its preparation method, belonging to the field of sanitary product technology. The fabric of this invention comprises, from top to bottom: a modified absorbent and quick-drying cotton layer, a hydrophobic modified non-woven fabric layer, and a breathable and water-wicking layer. Its preparation involves layering the three materials with hot-melt adhesive, hot-pressing them together at 130-150℃ and 3-5MPa, and simultaneously hot-rolling to form parallel guiding stripes 0.3-0.8mm wide and 0.2-0.5mm high. This structure utilizes the hydrophilic-hydrophobic gradient difference and surface physical guide grooves to synergistically achieve instantaneous absorption of liquid from the surface layer, unidirectional transport through the middle layer to the bottom layer, and rapid penetration into the absorbent core, effectively keeping the surface layer dry, significantly improving the ability to prevent side leakage and backflow, while also possessing good breathability.

Description

Technical Field

[0001] This invention relates to the field of hygiene products technology, and in particular to a multi-layer sanitary napkin fabric capable of guiding the rapid directional transport of liquids and its preparation method. Background Technology

[0002] Sanitary napkins are essential for women's daily menstrual care, and their core performance depends on the liquid handling capabilities of the absorbent core and surface layer materials. Traditional sanitary napkins typically have a single non-woven fabric surface layer, primarily for liquid permeation. However, this structure has significant shortcomings: Uneven liquid diffusion: After the liquid comes into contact with the surface layer, it tends to diffuse laterally and cannot be quickly guided to the absorber core below, resulting in local saturation while other areas are not utilized, which reduces absorption efficiency and service life.

[0003] Strong surface dampness: The slow liquid penetration rate results in a lot of residual liquid on the surface, causing a damp and sticky discomfort and affecting the comfort of use.

[0004] There is a risk of reverse osmosis: when the user is under pressure, the liquid in the absorbent core may be squeezed back into the surface layer, causing secondary pollution and discomfort.

[0005] Limited ability to prevent side leakage: Relying solely on the leak-proof edge and absorbent core is insufficient to control the initial diffusion of liquid on the surface layer, making it prone to side leakage.

[0006] In existing technologies, although attempts have been made to combine different materials, the structures are often complex or the wettability gradient between layers is poorly designed, failing to achieve rapid, directional, and unidirectional transport of liquid from the contact surface to the storage layer. Summary of the Invention

[0007] In view of this, the present invention provides a multi-layer sanitary napkin fabric capable of guiding the rapid directional transport of liquid and a method for preparing the same. The sanitary napkin fabric prepared by this method has a multi-layer structure, which can quickly absorb liquid and directionally transport it to the absorbent core, keeping the surface of the sanitary napkin dry, while improving the ability to prevent side leakage and reducing liquid backflow.

[0008] The multi-layer sanitary napkin fabric of the present invention, which can guide the rapid directional transport of liquid, consists of, from top to bottom, a modified absorbent and quick-drying cotton layer, a hydrophobic modified non-woven fabric layer, and a breathable and water-wicking layer.

[0009] Preferably, the thickness of the modified absorbent and quick-drying cotton layer is 0.3-0.5 mm, the thickness of the hydrophobic modified nonwoven fabric layer is 0.2-0.4 mm, and the thickness of the breathable and water-wicking layer is 0.5-0.8 mm.

[0010] Preferably, the material of the modified absorbent and quick-drying cotton layer is modified absorbent and quick-drying cotton, and its preparation method includes the following steps: mixing 5-7g of cotton fiber with 200-220mL of water, stirring and swelling at 55-60℃ for 1-1.2 hours to fully wet the fiber; then adding 2-3% by weight of the monomer initiator potassium persulfate, continuously stirring and heating to 65-70℃ for 8-10 minutes to activate the cotton fiber solution; mixing 10-15g of acrylic monomer with 15-18mL of 20% by weight sodium hydroxide solution, stirring in an ice-water bath for 10-15 minutes, then adding dropwise to the activated cotton fiber solution, and reacting at 65-70℃ for 2-3 hours to obtain the modified absorbent and quick-drying cotton.

[0011] Preferably, the material of the hydrophobic modified nonwoven fabric layer is hydrophobic modified nonwoven fabric, and the preparation method includes the following steps: (1) Prepare a water repellent solution with a concentration of 8-15 wt%, and add 0.5-1.0 wt% of crosslinking agent polyaziridinium and 0.1-0.3 wt% of penetrant fatty alcohol polyoxyethylene ether to obtain the padding working solution; (2) Use polypropylene nonwoven fabric with a weight of 20-30 gsm as the base material and adopt the "two dips and two rolls" process with a roll-in rate of 70%-90% to make the water repellent evenly adhere to the fiber surface. (3) Then pre-dry at 100-120℃ for 2-3 minutes to remove most of the moisture, and then bake at 150-170℃ for 1.5-3 minutes to allow the fluoride to complete the orientation arrangement on the fiber surface and fully react with the crosslinking agent; (4) After the reaction is complete, cool to room temperature, wash repeatedly with deionized water, filter until the filtrate is neutral, and dry in a vacuum drying oven at 75-80℃ to constant weight to obtain hydrophobic modified nonwoven fabric.

[0012] More preferably, the water repellent in step (2) comprises the following raw materials in parts by weight: 2-4 parts of isophorone diisocyanate; 2-4 parts of polyester diol; 2-4 parts of trimethylolpropane; 4-6 parts of N-methyldiethanolamine; and 3-5 parts of amino-terminated dimethylpolysiloxane.

[0013] Preferably, the breathable and water-permeable layer is a breathable and water-permeable nonwoven fabric, and its preparation method includes the following steps: (1) Hydrophilic fibers, low-melting-point fibers and hydrophobic fibers are mixed in a mass ratio of 60-70:20-30:10-20, and water is added to prepare a fiber suspension slurry with a concentration of 0.05%-0.1%, which is then deposited on a forming screen to form a wet fiber web; (2) Hydroentangle the upper layer of the wet fiber web for 10-20 minutes under a pressure of 40-60 bar to fully entangle the surface hydrophilic fibers and form a porous and loose structure. (3) Under a pressure of 80-120 bar, perform hydroentanglement on the upper and lower layers of the wet fiber web for 10-20 min respectively to ensure that the hydrophobic fiber layer is also fully entangled and densified, and firmly bonded to the overall structure, but without destroying the gradient distribution; (4) The wet fiber web after hydroentanglement is treated under hot air at 125-135℃ for 2-4 minutes to melt the low melting point fibers and form a strong "spot welding" bond in the whole layer, especially between the interfaces, and finally shape a three-dimensional breathable and water-wicking nonwoven fabric with a porous structure.

[0014] More preferably, the hydrophilic fiber is lyocell fiber with a length of 2-4 mm, providing excellent hydrophilicity and capillary effect; the low melting point fiber is a filament with a density of 10-450 D; and the hydrophobic fiber is a short hydrophobic polypropylene fiber with a density of 1.2-1.5 D and a length of 3-4 mm.

[0015] More preferably, the method for preparing the polypropylene hydrophobic short fibers includes the following steps: The polypropylene hydrophobic short fibers are obtained by immersing them in a 2-3 wt% water-repellent solution at room temperature for 2-3 hours. The water-repellent comprises the following raw materials in parts by weight: 2-4 parts isophorone diisocyanate; 2-4 parts polyester diol; 2-4 parts trimethylolpropane; 4-6 parts N-methyldiethanolamine; and 3-5 parts amino-terminated dimethylpolysiloxane.

[0016] The method for preparing the multi-layer sanitary napkin fabric capable of guiding rapid directional transport of liquid, as described in this invention, includes the following steps: (1) Apply hot melt adhesive between layers by spraying or roller coating; (2) The materials are precisely stacked and passed through heated rollers to activate the hot melt adhesive and complete the interlayer bonding; (3) Cooling and shaping to obtain the sanitary napkin fabric.

[0017] Preferably, in step (2), the heating roller process involves hot rolling and engraving to form parallel, equidistant raised stripes. The stripe width is 0.3-0.8 mm, the stripe height is 0.2-0.5 mm, and the stripe spacing is 1.0-2.0 mm. This gives the fabric a flow-guiding structure. This structure not only activates the hot melt adhesive to achieve a strong interlayer bonding, but also creates macroscopic capillary channels on the fabric surface. In conjunction with the microscopic moisture-wicking fibers, it strongly guides the liquid to flow rapidly along the stripe direction (usually the longitudinal direction of the sanitary napkin).

[0018] Preferably, the temperature of the heating roller in step (2) is 130-150℃, the pressure is 3-5 MPa, and the hot pressing time is 0.5-1.5 seconds.

[0019] Compared with the prior art, the present invention has the following beneficial effects: (1) Rapid absorption and directional delivery: The modified cotton in the upper layer absorbs the liquid rapidly within 1-3 seconds and quickly transfers it to the middle layer; the hydrophobic guide stripes in the middle layer confine the liquid within the longitudinal channel, achieving "one-line" rapid infiltration and avoiding side leakage.

[0020] (2) High efficiency in preventing backflow and keeping the surface dry: The lower breathable and water-conducting layer promotes the downward penetration of liquid and locks it in the bottom layer through the hydrophilic-hydrophobic gradient distribution; the upper cotton fiber has moderate water retention capacity after modification, and combined with the rapid flow of the middle layer, the surface contact angle remains at a high level after absorption, significantly improving the dryness.

[0021] (3) Stable structure and lightweight comfort: The three layers are bonded together by hot melt adhesive, which ensures the interlayer bonding strength and maintains the overall softness and breathability of the fabric; the total thickness is relatively thin, which is suitable for ultra-thin sanitary napkin design and is comfortable to wear.

[0022] (4) Excellent breathability, reducing stuffiness: The three-dimensional porous structure of the lower layer of spunlace fiber web, combined with the "spot welding" bonding of low melting point fiber, maintains high breathability while ensuring water conduction, which helps to reduce the accumulation of moisture and heat.

[0023] (5) Skin-friendly and safe and environmentally friendly: The surface layer is made of natural modified fiber, which does not contain harmful monomer residues and has a good skin-friendly effect. Detailed Implementation

[0024] The present invention will be further described below with reference to embodiments. In the specific embodiments of the present invention, unless otherwise specified, the raw materials are all conventional raw materials purchased from the market, and unless otherwise specified, the methods are all conventional methods in the art. In the specific embodiments of the present invention, unless otherwise specified, the amount or proportion of raw materials used are all mass ratios.

[0025] Example 1 A method for preparing modified absorbent and quick-drying cotton, comprising the following steps: (1) Mix 5g of cotton fiber with 200mL of water and stir at 60℃ for 1 hour to fully wet the fiber; add 2.2% of the monomer mass of potassium persulfate as an initiator, stir continuously and heat to 70℃ for 10 minutes to activate the cotton fiber solution. (2) Mix 10g of acrylic monomer with 15mL of 20% sodium hydroxide solution, stir in an ice-water bath for 10 minutes, then add dropwise to the activated cotton fiber solution, and react at 65℃ for 2.5 hours to obtain the modified absorbent and quick-drying cotton.

[0026] Example 2 A method for preparing a hydrophobically modified nonwoven fabric, comprising the following steps: (1) Prepare a water repellent solution with a concentration of 10 wt%, and add 0.7 wt% of crosslinking agent polyaziridinium and 0.2 wt% of penetrant fatty alcohol polyoxyethylene ether to obtain the padding working solution; (2) Polypropylene nonwoven fabric with a weight of 25 gsm is selected as the base material and the "two dips and two rolls" process is adopted with a roll-in rate of 82% to make the water repellent evenly adhere to the fiber surface. (3) Then pre-bake at 110°C for 3 minutes, followed by high-temperature baking at 155°C for 2 minutes; (4) After the reaction is complete, cool to room temperature, wash repeatedly with deionized water and filter until the filtrate is neutral, and dry in a vacuum drying oven at 80°C to constant weight to obtain hydrophobic modified nonwoven fabric.

[0027] The water repellent is composed of the following raw materials in parts by weight: 3 parts isophorone diisocyanate; 2 parts polyester diol; 3 parts trimethylolpropane; 5 parts N-methyldiethanolamine; and 4 parts amino-terminated dimethylpolysiloxane.

[0028] Example 3 A method for preparing a breathable and water-wicking nonwoven fabric, comprising the following steps: (1) Hydrophilic fibers, low melting point fibers and hydrophobic fibers are mixed in a mass ratio of 65:20:18, and water is added to prepare a fiber suspension slurry with a mass concentration of 0.07%, which is then deposited on a forming screen to form a wet fiber web; (2) Perform hydroentangling on the upper layer of the wet fiber web for 20 minutes under a pressure of 55 bar; (3) Under a pressure of 100 bar, the upper and lower layers of the wet fiber web were subjected to hydroentangling for 20 min respectively; (4) The wet fiber web after hydroentanglement is treated with hot air at 135°C for 4 minutes to form a three-dimensional air-permeable and water-wicking nonwoven fabric with a porous structure.

[0029] The hydrophilic fiber is lyocell fiber with a length of 2-4 mm; the low melting point fiber is a filament of 390-400D; and the hydrophobic fiber is a short hydrophobic polypropylene fiber of 1.2-1.5D with a length of 3-4 mm.

[0030] The preparation method of the aforementioned hydrophobic short polypropylene fibers comprises the following steps: The polypropylene hydrophobic short fibers were immersed in a 3wt% water-repellent solution at room temperature for 3 hours to obtain the polypropylene hydrophobic short fibers; the water-repellent was composed of the following raw materials in parts by weight: 4 parts isophorone diisocyanate; 3 parts polyester diol; 3 parts trimethylolpropane; 5 parts N-methyldiethanolamine; and 4 parts amino-terminated dimethyl polysiloxane.

[0031] Example 4 A multi-layer sanitary napkin fabric capable of guiding the rapid directional transport of liquid consists of, from top to bottom, a modified absorbent and quick-drying cotton layer, a hydrophobic modified non-woven fabric layer, and a breathable and water-wicking layer. The thickness of the modified absorbent and quick-drying cotton layer is 0.3 mm, the thickness of the hydrophobic modified nonwoven fabric layer is 0.4 mm, and the thickness of the breathable and water-wicking layer is 0.5 mm.

[0032] The preparation method of the multi-layer sanitary napkin fabric capable of guiding rapid directional transport of liquid includes the following steps: (1) Apply hot melt adhesive between layers by spraying or roller coating; (2) The materials are precisely stacked and passed through a heated roller to activate the hot melt adhesive and complete the interlayer bonding. During the heating process, hot rolling is performed to create raised stripes with parallel and equidistant spacing. The stripe width is 0.4 mm, the stripe height is 0.4 mm, and the stripe spacing is 1 mm. The temperature of the heated roller is 135℃, the pressure is 3.5 MPa, and the hot pressing time is 0.8 seconds. (3) Cooling and shaping to obtain the sanitary napkin fabric.

[0033] Comparative Example 1 A multi-layer sanitary napkin fabric, which differs from Example 4 in that Comparative Example 1 does not contain a hydrophobic modified nonwoven layer.

[0034] Comparative Example 2 A multi-layer sanitary napkin fabric, which differs from Example 4 in that Comparative Example 2 does not contain a breathable and water-wicking layer.

[0035] Comparative Example 3 A multi-layer sanitary napkin fabric, which differs from Example 4 in that Comparative Example 3 does not contain a hydrophobic modified nonwoven layer and a breathable and water-wicking layer.

[0036] The water absorption (weight gain) and quick-drying properties of the fabrics prepared in Example 4 and Comparative Examples 1-3 were tested, and the results are shown in Table 1.

[0037] Table 1

[0038] Sanitary napkins were prepared using the multi-layer sanitary napkin fabrics of Example 4 and Comparative Examples 1-3 as the surface layer, and their reverse seepage performance was tested. The specific method is as follows: Take 1250ml of clean water and add 10 drops of blue ink to obtain an ink solution. Then pour 10ml, 25ml, and 50ml of the ink solution onto a sanitary napkin. Cover the sanitary napkin with a facial tissue (a three-layer facial tissue conforming to GB / T 20808 standard; the same type of facial tissue was used in the experiment). After standing for 1 minute, observe whether there are water stains on the surface of the facial tissue. The results are shown in Table 2.

[0039] Table 2

[0040] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A multi-layer sanitary napkin fabric capable of guiding the rapid directional transport of liquid, characterized in that, From top to bottom, the layers are: a modified absorbent and quick-drying cotton layer, a hydrophobic modified nonwoven fabric layer, and a breathable and water-wicking layer.

2. The multi-layer sanitary napkin fabric capable of guiding rapid directional transport of liquid according to claim 1, characterized in that, The thickness of the modified absorbent and quick-drying cotton layer is 0.3-0.5 mm, the thickness of the hydrophobic modified nonwoven fabric layer is 0.2-0.4 mm, and the thickness of the breathable and water-wicking layer is 0.5-0.8 mm.

3. The multi-layer sanitary napkin fabric capable of guiding rapid directional transport of liquid according to claim 1, characterized in that, The modified absorbent and quick-drying cotton layer is made of modified absorbent and quick-drying cotton, and its preparation method includes the following steps: Cotton fibers and water are mixed and stirred to swell for 1-1.2 hours; then an initiator is added and stirred to activate the solution, resulting in an activated cotton fiber solution; acrylic monomer and sodium hydroxide solution are mixed, stirred in an ice-water bath, and then added dropwise to the activated cotton fiber solution. The mixture is reacted at 65-70°C for 2-3 hours to obtain the modified absorbent and quick-drying cotton.

4. The multi-layer sanitary napkin fabric capable of guiding rapid directional transport of liquid according to claim 1, characterized in that, The material of the hydrophobic modified nonwoven fabric layer is hydrophobic modified nonwoven fabric, and the preparation method includes the following steps: (1) Prepare a water repellent solution with a concentration of 8-15 wt%, and add 0.5-1.0 wt% of crosslinking agent and 0.1-0.3 wt% of penetrant to obtain the padding working solution; (2) Use polypropylene nonwoven fabric with a basis weight of 20-30 gsm as the base material, and adopt the "two-dip two-roll" process with a roll-off rate of 70%-90%; (3) Then pre-bake at 100-120℃ for 2-3 minutes, followed by high-temperature baking at 150-170℃ for 1.5-3 minutes; (4) After the reaction is complete, cool to room temperature, wash repeatedly with deionized water, filter until the filtrate is neutral, and dry in a vacuum drying oven at 75-80℃ to constant weight to obtain hydrophobic modified nonwoven fabric.

5. The multi-layer sanitary napkin fabric capable of guiding rapid directional transport of liquid according to claim 4, characterized in that, The water repellent in step (2) comprises the following raw materials in parts by weight: 2-4 parts isophorone diisocyanate; 2-4 parts polyester diol; 2-4 parts trimethylolpropane; 4-6 parts N-methyldiethanolamine; and 3-5 parts amino-terminated dimethylpolysiloxane.

6. The multi-layer sanitary napkin fabric capable of guiding rapid directional transport of liquid according to claim 1, characterized in that, The breathable and water-permeable layer is a breathable and water-permeable nonwoven fabric, and its preparation method includes the following steps: (1) Mix hydrophilic fibers, low melting point fibers and hydrophobic fibers in a mass ratio of 60-70:20-30:10-20, add water to pulp, and deposit on a molding screen to form a wet fiber web; (2) Perform hydroentangling on the upper layer of the wet fiber web for 10-20 minutes under a pressure of 40-60 bar; (3) Under a pressure of 80-120 bar, perform hydroentangling on the upper and lower layers of the wet fiber web for 10-20 min respectively; (4) The wet fiber web after hydroentanglement is treated with hot air at 125-135℃ for 2-4 minutes to obtain the breathable and water-wicking nonwoven fabric.

7. The multi-layer sanitary napkin fabric capable of guiding rapid directional transport of liquid according to claim 6, characterized in that, The hydrophilic fiber is lyocell fiber with a length of 2-4 mm; the low melting point fiber is a filament with a density of 10-450 D; and the hydrophobic fiber is a short hydrophobic polypropylene fiber with a density of 1.2-1.5 D and a length of 3-4 mm.

8. The method for preparing the multi-layer sanitary napkin fabric capable of guiding rapid directional transport of liquid according to claim 1, characterized in that, Includes the following steps: (1) Apply hot melt adhesive between layers by spraying or roller coating; (2) The materials are precisely stacked and passed through heated rollers to activate the hot melt adhesive and complete the interlayer bonding; (3) Cooling and shaping to obtain the sanitary napkin fabric.

9. The method for preparing the multi-layer sanitary napkin fabric capable of guiding rapid directional transport of liquid according to claim 8, characterized in that, In step (2), the heated roller process is used to perform hot rolling engraving to form raised stripes with parallel and equidistant spacing. The stripe width is 0.3-0.8 mm, the stripe height is 0.2-0.5 mm, and the stripe spacing is 1.0-2.0 mm.

10. The method for preparing the multi-layer sanitary napkin fabric capable of guiding rapid directional transport of liquid according to claim 8, characterized in that, The temperature of the heating roller in step (2) is 130-150℃, the pressure is 3-5 MPa, and the hot pressing time is 0.5-1.5 seconds.

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