A 3D sanitary napkin based on viscose and ES fiber and its preparation method

Abstract

This invention belongs to the technical field of sanitary napkins, specifically relating to a 3D sanitary napkin based on viscose and ES fibers and its preparation method. The 3D sanitary napkin based on viscose and ES fibers comprises, from top to bottom, a surface layer, a flow-distribution layer, a core layer, and a bottom layer. Through material compounding, structural optimization, and the preparation of resin raw materials, this invention systematically addresses the problems of poor absorption, severe reverse osmosis, and structural collapse associated with traditional sanitary napkin products, meeting women's diverse needs for high-quality sanitary products.

Description

Technical Field

[0001] The present invention belongs to the technical field of sanitary napkins, and in particular relates to a 3D sanitary napkin based on viscose yarn and ES fiber and a preparation method thereof. Background Art

[0002] As women's health awareness increases, sanitary napkins, as essential menstrual products, are gaining widespread attention for their functionality, comfort, and safety. Traditional sanitary napkins still face numerous technical bottlenecks in material selection, structural design, and fluid management.

[0003] First, there are limitations to the surface material. Traditional sanitary napkins often use a single viscose fiber or polypropylene non-woven fabric for the surface, which lacks both hydrophilicity and structural strength. While viscose fiber is highly hydrophilic, it suffers from poor thermal stability and cannot effectively maintain a 3D embossed structure. Pure PP fiber, on the other hand, is highly hydrophobic, resulting in slow initial liquid penetration, which in turn affects liquid absorption, making the sanitary napkin's surface matte and uncomfortable to wear. Secondly, there are issues with the absorption efficiency and reverse osmosis of the distribution layer. Traditional sanitary napkins often use a single fiber material (such as regular non-woven fabric or chopped fibers) for the distribution layer, which lacks rapid lateral diffusion of liquid, leading to liquid accumulation on the surface and high rewet rates. The core layer also faces performance bottlenecks. Most cores rely on a composite of superabsorbent resin and wood pulp. Wood pulp fibers tend to clump after absorbing liquid, hindering the expansion of the SAP and limiting absorption rate. Furthermore, the uneven distribution of SAP particles and the lack of mechanical support make them prone to rewetting when subjected to pressure, increasing the risk of lateral leakage.

[0004] Therefore, it is necessary to develop a 3D sanitary napkin based on viscose and ES fiber. Through material compounding, structural optimization and raw material preparation, the problems of poor absorption performance, severe reverse osmosis, and easy structural collapse of traditional sanitary napkin products can be systematically solved, providing users with safer, more comfortable and efficient sanitary care solutions. Summary of the Invention

[0005] The purpose of the present invention is to provide a 3D sanitary napkin based on viscose and ES fiber and a preparation method thereof, which can not only improve the absorption rate and absorption speed of the sanitary napkin, but also reduce back seepage and improve user comfort.

[0006] A 3D sanitary napkin based on viscose and ES fiber, whose structure from top to bottom is surface layer, diversion layer, core layer and bottom layer.

[0007] Preferably, the surface layer is prepared from raw materials including first viscose fiber and first ES fiber.

[0008] Preferably, the mass ratio of the first viscose fiber to the first ES fiber is (1-2):1; more preferably, it is 3:2.

[0009] Preferably, the first viscose fiber has a fineness of 1.4-1.6 dtex and a length of 35-40 mm.

[0010] Preferably, the first ES fiber is a PP skin layer / PE core layer with a skin-core ratio of 3:7, a fineness of 2.0-2.4 dtex, and a length of 50-52 mm.

[0011] The surface layer is obtained by compounding a specific first viscose fiber and a first ES fiber, which can accelerate the liquid absorption rate, improve the surface dryness, and improve the liquid absorption rate. This may be because the specific viscose fiber and ES fiber work together, and the hydroxyl groups in the viscose fiber form a hydrogen bond network, which accelerates liquid infiltration through capillary action; the PP skin layer of the ES fiber maintains the embossed three-dimensionality, and the PE core layer melts to form bonding points. The compounding of the two increases the porosity of the surface layer, thereby increasing the liquid absorption rate. A high proportion of viscose fiber can not only reduce the contact angle, increase the additional pressure difference and capillary flow, accelerate the flow of liquid, but also reduce friction and improve tactile comfort. In addition, by selecting fibers of different fineness, the mixture of coarse and fine fibers will fill the gaps between each other, and the viscose fiber has good hygroscopicity, and the fiber's direct absorption performance of water molecules is enhanced, thereby increasing the liquid absorption rate of the sanitary napkin. However, the proportion of viscose fiber should not be too high, as it will affect the above-mentioned performance effects.

[0012] Preferably, the guide layer comprises an upper guide layer, a middle guide layer and a lower guide layer.

[0013] Preferably, the raw material for preparing the upper guide layer includes second ES fibers.

[0014] Preferably, the second ES fiber is PP skin / PE core, with a skin-core ratio of 2:3, an eccentricity of 53%-57%, a curl of 8-12 / 5cm, a fineness of 5.8-6.2 dtex, and a length of 50-52 mm.

[0015] Preferably, the raw material for preparing the middle guide layer includes third ES fiber.

[0016] Preferably, the third ES fiber is PP skin / PE core, with a skin-core ratio of 2:3, an eccentricity of 53%-57%, a curl of 12-15 / 5cm, a fineness of 2.8-3.2dtex, and a length of 35-40mm.

[0017] Preferably, the raw material for preparing the lower guide layer includes fourth ES fibers.

[0018] Preferably, the fourth ES fiber PP skin layer / PE core layer has a skin-core ratio of 2:3, an eccentricity of 53%-57%, a curl of 5-10 / 5cm, a fineness of 1.4-1.6 dtex, and a length of 35-40 mm.

[0019] By selecting different ES fibers for preparation, not only can the absorption speed be increased, but also the amount of back seepage can be reduced. This may be because ES fibers of different fineness are first selected and arranged in sequence. The fibers of the upper diversion layer have a large diameter, which not only has high fluffiness, forming a three-dimensional space, and quickly diverting the liquid laterally, but also forms a large-aperture channel, using low capillary resistance to achieve rapid liquid infiltration and increase the diversion speed; the fibers of the middle diversion layer have moderate fineness and high curl, forming a water storage layer to prevent liquid accumulation. The liquid is absorbed by the middle layer before penetrating into the core, reducing surface overload. At the same time, the high curl of the middle layer forms wavy pores, which induce local turbulence, break the surface tension of the liquid, and promote lateral diffusion; the fine fibers of the lower layer are closely arranged to form a barrier layer to prevent liquid back seepage. In addition, the ES fibers selected for the diversion layer are all eccentric fibers. The offset of the PE core layer causes asymmetric melting, and after cooling, a unidirectional groove is formed, which produces a contact angle difference and drives the liquid to move in a directional manner. The eccentric structure also makes the fibers curl more tightly, increases porosity, reduces liquid penetration resistance, promotes rapid lateral diffusion of liquid between fibers, and increases flow diversion speed.

[0020] Preferably, the core layer is prepared from raw materials including super absorbent resin, fifth ES fiber and second viscose fiber.

[0021] Preferably, the mass ratio of the superabsorbent resin, the fifth ES fiber and the second viscose fiber is (2.5-3):(1-1.5):1; more preferably, it is 11:5:4.

[0022] By combining superabsorbent resin, ES fiber, and viscose fiber to prepare the core layer, it is possible to increase the absorption rate and absorption stability while increasing the absorption ratio. This may be due to the synergistic effect of the three. The carboxyl groups in the superabsorbent resin lock water through hydrogen bonds and osmotic pressure, and the cross-linked network expands to fill the core pores. The use of hollow ES fibers not only reserves expansion space to prevent the core from rupturing under pressure, but also accelerates the lateral diffusion of liquid in the internal channels of the hollow fibers, avoiding local SAP overload and affecting the liquid absorption effect. The hydroxyl groups in the viscose fiber quickly guide the liquid to the superabsorbent resin through capillary action, shortening the infiltration time. However, despite the use of ES fiber and viscose fiber for compounding, the superabsorbent resin still has the risk of collapse after absorbing water. In addition, the superabsorbent resins on the market have limited water absorption effect and slow absorption rate, which affects the various performance of sanitary napkins.

[0023] Preferably, the raw materials for preparing the superabsorbent resin include, by weight, 60-65 parts of acrylic acid, 5-8 parts of acrylamide, 3-5 parts of sodium propylene sulfonate, 9-15 parts of an inorganic modifier, 1-2 parts of modified carboxymethyl chitosan, 0.8-1.2 parts of a crosslinking agent, 0.1-0.4 parts of an initiator, and 80-100 parts of deionized water.

[0024] By selecting acrylic acid, acrylamide, and sodium propylene sulfonate and compounding them in the right proportions, the superabsorbent resin can simultaneously increase its water absorption rate and salt absorption capacity, thereby enhancing its absorption of menstrual blood. This is likely due to the synergistic effect of the three acrylic monomers: acrylic acid, as the primary water-absorbing group, provides high water absorption, while the amide group in acrylamide strongly binds to salt ions, thereby enhancing salt absorption, and the introduction of sulfonic acid groups improves salt tolerance and surface hydrophilicity. These three factors work synergistically to enhance the superabsorbent resin's absorption efficiency.

[0025] Preferably, the inorganic modifier includes modified halloysite nanotubes, modified montmorillonite and modified brucite fibers.

[0026] Preferably, the mass ratio of the modified halloysite nanotubes, modified montmorillonite and modified brucite fibers is (2-4):(1-3):1; more preferably, it is 3:2:1.

[0027] By using halloysite nanotubes, montmorillonite, and brucite fibers as inorganic modifiers, it is possible to increase both the water absorption rate and the water absorption ratio. This is likely due to the synergistic effect of the three ingredients: the halloysite tubular structure forms micron-sized pores that accelerate liquid diffusion, thereby increasing the water absorption rate; the montmorillonite layered structure absorbs salt (menstrual blood contains salt), improving salt tolerance; and the high tensile strength of brucite fibers enhances the gel strength of the superabsorbent resin, preventing collapse and thus improving its overall water absorption efficiency. However, these three raw materials are inorganic and have poor compatibility with organic systems.

[0028] The preparation method of the modified halloysite nanotubes comprises the following steps: dispersing the halloysite nanotubes in an ethanol aqueous solution with a mass fraction of 65%-75%, adding a silane coupling agent, refluxing at 80° C. for 4 hours, centrifuging and washing until neutral, and drying to obtain the modified halloysite nanotubes.

[0029] Preferably, the diameter of the halloysite nanotubes is 50-300 nm and the length is 1-10 μm.

[0030] In some preferred embodiments, the halloysite nanotubes are from Jiangsu Xianfeng Nanomaterial Technology Co., Ltd.

[0031] Preferably, the solid-to-liquid ratio of the halloysite nanotubes to the ethanol aqueous solution with a mass fraction of 65%-75% is 1 g: (10-20) mL.

[0032] Preferably, the silane coupling agent is KH-550.

[0033] Preferably, the added amount of the silane coupling agent is 1%-2% of the mass of the halloysite nanotubes.

[0034] The preparation method of the modified montmorillonite comprises the following steps: dissolving montmorillonite and hexadecyltrimethylammonium bromide in deionized water, stirring for 2 hours, centrifuging and washing until neutral, and drying to obtain the modified montmorillonite.

[0035] Preferably, the aspect ratio of the montmorillonite is 200-400, and the average particle size is 16-22 μm.

[0036] In some preferred embodiments, the montmorillonite comes from Jiangsu Xianfeng Nanomaterial Technology Co., Ltd.

[0037] Preferably, the solid-liquid ratio of the montmorillonite to deionized water is 1 g: (10-20) mL.

[0038] Preferably, the amount of cetyltrimethylammonium bromide added is 4%-6% of the mass of montmorillonite.

[0039] The preparation method of the modified brucite fiber comprises the following steps: placing the brucite fiber and a modifier in an acetic acid aqueous solution with a pH of 4, subjecting the solution to reflux reaction at room temperature for 2 hours, centrifugally washing the solution until it becomes neutral, and drying the solution.

[0040] Preferably, the brucite fiber has a specific gravity of 2.4-2.5 and a tensile strength of 880-1300 MPa.

[0041] In some preferred embodiments, the brucite fiber comes from Hebei Hongli Sepiolite Wool Co., Ltd.

[0042] Preferably, the modifier is acrylic acid.

[0043] Preferably, the solid-to-liquid ratio of the brucite fiber to the acetic acid aqueous solution is 1 g: (10-20) mL.

[0044] Preferably, the amount of the modifier added is 1%-3% of the mass of the brucite fiber.

[0045] Modifying these three inorganic substances with different modifiers can further enhance the beneficial effects of the modification. By modifying halloysite nanotubes with a silane coupling agent, the alkoxy groups of the silane coupling agent react with the hydroxyl groups on the halloysite surface to form covalent bonds, improving compatibility with acrylic acid monomers, reducing agglomeration, and further enhancing its water absorption rate. By using hexadecyltrimethylammonium bromide to cationize montmorillonite, the quaternary ammonium salt of hexadecyltrimethylammonium bromide inserts into the montmorillonite interlayers, expanding the interlayer spacing and further enhancing salt adsorption capacity. By treating brucite fibers with acrylic acid carboxylation, acrylic acid reacts with the hydroxyl groups on the brucite surface to form carboxyl groups, strengthening the interfacial bonding with the superabsorbent resin and further enhancing structural stability. Furthermore, using modified carboxymethyl chitosan as an organic modifier can further increase the water absorption rate while also enhancing the antibacterial effect of the sanitary napkin. This may be because after grafting quaternary ammonium groups on carboxymethyl chitosan, it can not only inhibit bacteria, but the carboxyl groups on it can also enhance the surface hydrophilicity of the superabsorbent resin and accelerate water absorption.

[0046] The preparation method of the modified carboxymethyl chitosan comprises the following steps: adding carboxymethyl chitosan to an ethanol aqueous solution with a mass fraction of 75%-85%, then adding epichlorohydrin, adjusting the pH of the system to 10-12, reacting at 50° C. for 2 hours, centrifuging and washing until neutral, and drying to obtain the modified carboxymethyl chitosan.

[0047] Preferably, the solid-to-liquid ratio of the carboxymethyl chitosan to the ethanol aqueous solution with a mass fraction of 75%-85% is 1 g: (90-110) mL.

[0048] Preferably, the added amount of epichlorohydrin is 4%-6% of the mass of carboxymethyl chitosan.

[0049] By combining inorganic and organic modifiers and reinforcing them with functional fibers, this product overcomes the issues of slow flow and structural collapse associated with traditional superabsorbent resins. The optimized ratios of each raw material and modification method ensure compatibility with the acrylic matrix, ultimately achieving the combined performance of superior absorption and rapid flow within the sanitary napkin core, meeting the stringent requirements of modern hygiene products.

[0050] The preparation method of the superabsorbent resin comprises the following steps:

[0051] A1. Dispersing an inorganic modifier, carboxymethyl cellulose, and modified carboxymethyl chitosan in a portion of deionized water, introducing nitrogen protection, and stirring at 70° C. for 30 minutes to obtain a dispersion; mixing a portion of the deionized water with acrylic acid, and slowly adding a mixture of sodium hydroxide and the remaining deionized water under an ice-water bath until the degree of neutralization reaches 60%-75%, thereby obtaining neutralized acrylic acid;

[0052] A2. After cooling the dispersion to 40°C, add the initiator and stir for 20 minutes. Then add the neutralized acrylic acid, acrylamide, sodium propylene sulfonate and cross-linking agent. Heat to 70°C and react for 3 hours. Then soak in 65%-75% ethanol aqueous solution for more than 1 hour, centrifuge and dry to constant weight, and grind through a 100-mesh sieve to obtain the product.

[0053] Preferably, the fifth ES fiber is a PP skin layer / PE core layer with a skin-core ratio of 1:3, a hollowness of ≥80%, and a density of 0.15-0.2 g / cm 3 , fineness is 4.3-4.6dtex, length is 43-46mm.

[0054] Preferably, the second viscose fiber has a fineness of 4.8-5.2 dtex and a length of 38-42 mm.

[0055] Preferably, the bottom layer is an ES / PE fiber composite breathable membrane.

[0056] Preferably, the raw materials for preparing the ES / PE fiber composite breathable membrane include first ES fibers and PE membrane.

[0057] Preferably, the PE base film has a gram weight of 50 g / m 2 , from Shenzhen Fuchanglong Packaging Materials Co., Ltd.

[0058] The method for preparing the 3D sanitary napkin based on viscose and ES fiber comprises the following steps:

[0059] S1. Surface layer preparation: The first viscose fiber and the first ES fiber are mixed and opened, combed into a fiber web with fiber orientation, and then laid parallel to form a fiber web, which is then placed on a 3D embossing machine for hot rolling to obtain the fiber web;

[0060] S2. Preparation of the guide layer: The raw materials of the upper guide layer, the middle guide layer, and the lower guide layer are loosened and combed into an upper fiber web, a middle fiber web, and a lower fiber web respectively; the middle fiber web is sent to an oven for hot air pre-bonding and then wave-formed to obtain a pre-treated middle fiber web; the pre-treated middle fiber web is superimposed with the upper fiber web and the lower fiber web, and then sent to a hot air through-drying oven for reinforcement.

[0061] S3. Preparation of the core layer: hollow ES fibers and viscose staple fibers are opened and mixed with superabsorbent resin, which is then laid into a fiber web using an air-laid device. At the same time, SAP is gradient-distributed using a layered laying technique. The core layer is then microwave-treated and hot-rolled to form a fiber web.

[0062] S4. Preparation of bottom layer: Lay the first ES fiber on the surface of PE film at a 45° angle, and control the surface density to 13-17 g / m 2, after hot rolling and qualitative treatment, it is obtained by plasma treatment;

[0063] S5. Preparation of three-dimensional sanitary napkin: stack the surface layer, the guide layer, the core layer and the bottom layer in order, and then perform gradient hot-melt compounding to obtain the sanitary napkin.

[0064] Preferably, in step S1, the surface density of the fiber web is 40-50 g / m 2 .

[0065] Preferably, in step S1, the specific process conditions of hot rolling forming are: temperature of 130-140° C., pressure of 0.25-0.3 MPa, and time of 1-2 min.

[0066] Preferably, in step S2, the surface density of the upper fiber web is 25-30 g / m 2 .

[0067] Preferably, in step S2, the surface density of the middle fiber web is 20-25 g / m 2 .

[0068] Preferably, in step S2, the surface density of the lower fiber web is 15-20 g / m 2 .

[0069] Preferably, in step S2, the conditions for hot air pre-bonding are: preheating temperature is 130-140° C., and heating time is 1-2 min.

[0070] Preferably, in step S2, when the waves are formed, the wavelength of the waves is set to 5 mm and the wave height is set to 2 mm.

[0071] Preferably, in step S2, the strengthening conditions are: temperature of 125-135° C., and heating time of 2-4 minutes.

[0072] Preferably, in step S3, the wind speed of the airflow forming the net is 15-20 m / s.

[0073] Preferably, in step S3, the surface density of the fiber web is 120-150 g / m 2 .

[0074] Preferably, in step S3, the gradient distribution is as follows: the upper layer SAP accounts for 60%, and the lower layer SAP accounts for 40%.

[0075] Preferably, in step S3, the specific process of microwave treatment is: frequency 2400-2500 MHz, power 4-6 kW, and time 20-40 s.

[0076] Preferably, in step S3, the specific process conditions of hot rolling forming are: temperature of 85-95° C., pressure of 0.04-0.05 MPa, and time of 10-20 s.

[0077] Preferably, in step S4, the specific process conditions of hot rolling forming are: temperature of 105-115° C., pressure of 0.7-1.0 MPa, and time of 6-10 s.

[0078] Preferably, in step S4, the specific conditions of the plasma treatment are: power 180-220 W, time 8-12 s.

[0079] Preferably, in step S5, the specific process of gradient hot melt lamination is: preheating zone, temperature 100°C, time 3s; bonding zone, temperature 120-130°C, time 5s, pressure 0.08MPa; shaping zone, temperature 80°C, time 2s.

[0080] Compared with the prior art, the advantages and beneficial effects of the present invention are:

[0081] 1. The 3D sanitary napkin based on viscose and ES fiber prepared by the present invention systematically solves the problems of poor absorption performance, severe reverse osmosis, and easy structural collapse of traditional sanitary napkin products through material compounding, structural optimization and preparation of resin raw materials, and meets women's diverse needs for high-quality sanitary products.

[0082] 2. The present invention selects a specific first viscose fiber and a first ES fiber to compound to obtain a surface layer, which can accelerate the liquid absorption speed, improve the surface dryness, and at the same time improve the liquid absorption rate.

[0083] 3. The present invention uses different ES fibers to prepare the product, which can not only increase the absorption speed but also reduce the back seepage amount.

[0084] 4. The present invention uses superabsorbent resin, ES fiber and adhesive fiber to prepare the core layer, which can improve the absorption rate and absorption stability while increasing the absorption ratio.

[0085] 5. The present invention selects acrylic acid, acrylamide, and sodium propylene sulfonate as three acrylic monomers and mixes them in proportion, thereby increasing the water absorption rate of the superabsorbent resin while improving its salt absorption capacity, thereby improving the absorbency of menstrual blood.

[0086] 6. The present invention uses halloysite nanotubes, montmorillonite and brucite fibers as inorganic modifiers, which can increase the water absorption rate and the water absorption ratio. At the same time, by modifying these three inorganic substances with different modifiers, the beneficial effects of the modification can be further enhanced. DETAILED DESCRIPTION

[0087] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0088] The raw materials used in the present invention are all commercially available, specifically:

[0089] The first viscose fiber has a fineness of 1.4-1.6 dtex and a length of 35-40 mm; the second viscose fiber has a fineness of 4.8-5.2 dtex and a length of 38-42 mm; both come from Shandong Fuhui Textile Technology Co., Ltd.

[0090] The first ES fiber is PP skin / PE core, with a skin-core ratio of 3:7, a fineness of 2.0-2.4 dtex, and a length of 50-52 mm; the second ES fiber is PP skin / PE core, with a skin-core ratio of 2:3, an eccentricity of 53%-57%, a crimp of 8-12 / 5 cm, a fineness of 5.8-6.2 dtex, and a length of 50-52 mm; the third ES fiber is PP skin / PE core, with a skin-core ratio of 2:3, an eccentricity of 53%-57%, The curl is 12-15 per 5cm, the fineness is 2.8-3.2 dtex, and the length is 35-40mm; the fourth ES fiber is PP skin / PE core, the skin-core ratio is 2:3, the eccentricity is 53%-57%, the curl is 5-10 per 5cm, the fineness is 1.4-1.6 dtex, and the length is 35-40mm; the fifth ES fiber is PP skin / PE core, the skin-core ratio is 1:3, the hollowness is ≥80%, and the density is 0.15-0.2g / cm 3 , fineness is 4.3-4.6dtex, length is 43-46mm; all from Hebei Jinyou New Material Technology Co., Ltd.

[0091] Halloysite nanotubes, with a diameter of 50-300nm and a length of 1-10μm; montmorillonite, with an aspect ratio of 200-400 and an average particle size of 16-22μm; both are from Jiangsu Xianfeng Nanomaterial Technology Co., Ltd.

[0092] Brucite fiber, with a specific gravity of 2.4-2.5 and a tensile strength of 880-1300 MPa; comes from Hebei Hongli Sepiolite Co., Ltd.

[0093] PE base film, weight 50g / m 2 , from Shenzhen Fuchanglong Packaging Materials Co., Ltd.

[0094] Example 1

[0095] This embodiment provides a 3D sanitary napkin based on viscose yarn and ES fiber, the structure of which from top to bottom is a surface layer, a guide layer, a core layer, and a bottom layer.

[0096] The surface layer is prepared from the first viscose fiber and the first ES fiber in a mass ratio of 3:2.

[0097] The guide layer is structured as an upper guide layer, a middle guide layer and a lower guide layer.

[0098] The raw material for preparing the upper guide layer is the second ES fiber.

[0099] The raw material for preparing the middle guide layer is the third ES fiber.

[0100] The raw material for preparing the lower guide layer is the fourth ES fiber.

[0101] The core layer is prepared from raw materials of super absorbent resin, fifth ES fiber and second viscose fiber, with a mass ratio of 11:5:4.

[0102] The raw materials for preparing the superabsorbent resin include, by weight, 62 parts of acrylic acid, 6 parts of acrylamide, 4 parts of sodium propylene sulfonate, 12 parts of an inorganic modifier, 1.5 parts of modified carboxymethyl chitosan, 1 part of a crosslinking agent, 0.2 parts of an initiator, and 90 parts of deionized water.

[0103] The inorganic modifiers are modified halloysite nanotubes, modified montmorillonite and modified brucite fibers, with a mass ratio of 3:2:1.

[0104] The preparation method of the modified halloysite nanotubes comprises the following steps: dispersing the halloysite nanotubes in a 70% by mass ethanol aqueous solution, adding a silane coupling agent, refluxing at 80° C. for 4 hours, centrifuging and washing until neutral, and drying to obtain the modified halloysite nanotubes.

[0105] The solid-to-liquid ratio of the halloysite nanotubes to the 70% by mass ethanol aqueous solution is 1 g:15 mL.

[0106] The silane coupling agent is KH-550.

[0107] The added amount of the silane coupling agent is 1.5% of the mass of the halloysite nanotubes.

[0108] The preparation method of the modified montmorillonite comprises the following steps: dissolving montmorillonite and hexadecyltrimethylammonium bromide in deionized water, stirring for 2 hours, centrifuging and washing until neutral, and drying to obtain the modified montmorillonite.

[0109] The solid-to-liquid ratio of the montmorillonite to deionized water is 1 g:15 mL.

[0110] The added amount of the hexadecyltrimethylammonium bromide is 5% of the mass of the montmorillonite.

[0111] The preparation method of the modified brucite fiber comprises the following steps: placing the brucite fiber and a modifier in an acetic acid aqueous solution with a pH of 4, subjecting the solution to reflux reaction at room temperature for 2 hours, centrifugally washing the solution until it becomes neutral, and drying the solution.

[0112] The modifier is acrylic acid.

[0113] The solid-to-liquid ratio of the brucite fiber to the acetic acid aqueous solution is 1 g:15 mL.

[0114] The addition amount of the modifier is 2% of the mass of the brucite fiber.

[0115] The preparation method of the modified carboxymethyl chitosan comprises the following steps: adding carboxymethyl chitosan to an ethanol aqueous solution with a mass fraction of 80%, then adding epichlorohydrin, adjusting the pH of the system to 11, reacting at 50° C. for 2 hours, centrifuging and washing until neutral, and drying to obtain the modified carboxymethyl chitosan.

[0116] The solid-liquid ratio of the carboxymethyl chitosan to the ethanol aqueous solution with a mass fraction of 80% is 1 g:100 mL.

[0117] The added amount of epichlorohydrin is 5% of the mass of carboxymethyl chitosan.

[0118] The preparation method of the superabsorbent resin comprises the following steps:

[0119] A1. Disperse an inorganic modifier, carboxymethyl cellulose, and modified carboxymethyl chitosan in 1 / 3 deionized water, introduce nitrogen protection, and stir at 70°C for 30 minutes to obtain a dispersion; mix 1 / 3 deionized water with acrylic acid, and slowly add a mixture of sodium hydroxide and 1 / 3 deionized water in an ice-water bath until the degree of neutralization reaches 60%-75%, thereby obtaining neutralized acrylic acid;

[0120] A2. After cooling the dispersion to 40°C, add the initiator and stir for 20 minutes. Then add the neutralized acrylic acid, acrylamide, sodium propylene sulfonate and cross-linking agent. Heat to 70°C and react for 3 hours. Then soak in 70% ethanol aqueous solution for more than 1 hour, centrifuge and dry to constant weight, and grind through a 100-mesh sieve to obtain the product.

[0121] The bottom layer is an ES / PE fiber composite breathable film, and the raw materials for preparing the film are first ES fibers and PE films.

[0122] The preparation method of the 3D sanitary napkin based on viscose and ES fiber comprises the following steps:

[0123] S1. Surface layer preparation: The first viscose fiber and the first ES fiber are mixed and opened, combed into a fiber web with fiber orientation, and then laid parallel to form a fiber web, which is then placed on a 3D embossing machine for hot rolling to obtain the fiber web;

[0124] S2. Preparation of the guide layer: The raw materials of the upper guide layer, the middle guide layer, and the lower guide layer are loosened and combed into an upper fiber web, a middle fiber web, and a lower fiber web respectively; the middle fiber web is sent to an oven for hot air pre-bonding and then wave-formed to obtain a pre-treated middle fiber web; the pre-treated middle fiber web is superimposed with the upper fiber web and the lower fiber web, and then sent to a hot air through-drying oven for reinforcement.

[0125] S3. Preparation of the core layer: hollow ES fibers and viscose staple fibers are opened and mixed with superabsorbent resin, which is then laid into a fiber web using an air-laid device. At the same time, SAP is gradient-distributed using a layered laying technique. The core layer is then microwave-treated and hot-rolled to form a fiber web.

[0126] S4. Preparation of bottom layer: The first ES fiber was laid on the surface of the PE film at a 45° angle, and the surface density was controlled to be 15g / m 2 , after hot rolling and qualitative treatment, it is obtained by plasma treatment;

[0127] S5. Preparation of three-dimensional sanitary napkin: stack the surface layer, the guide layer, the core layer and the bottom layer in order, and then perform gradient hot-melt compounding to obtain the sanitary napkin.

[0128] In step S1, the surface density of the fiber web is 45 g / m 2 .

[0129] In step S1, the specific process conditions of hot rolling forming are: temperature of 135° C., pressure of 0.28 MPa, and time of 1.5 min.

[0130] In step S2, the surface density of the upper fiber web is 28 g / m 2 .

[0131] In step S2, the surface density of the middle fiber web is 23g / m 2 .

[0132] In step S2, the surface density of the lower fiber web is 18 g / m 2 .

[0133] In step S2, the conditions for hot air pre-bonding are: preheating temperature is 135° C., and heating time is 1.5 min.

[0134] In step S2, when the waves are formed, the wavelength of the waves is set to 5 mm and the wave height is set to 2 mm.

[0135] In step S2, the strengthening conditions are: temperature of 130° C. and heating time of 3 minutes.

[0136] In step S3, the airflow speed of the net is 18 m / s.

[0137] In step S3, the surface density of the fiber web is 135 g / m 2 .

[0138] In step S3, the gradient distribution is as follows: the upper layer SAP accounts for 60%, and the lower layer SAP accounts for 40%.

[0139] In step S3, the specific process of microwave treatment is: frequency 2450 MHz, power 5 kW, and time 30 s.

[0140] In step S3, the specific process conditions of hot rolling forming are: temperature of 90° C., pressure of 0.04 MPa, and time of 15 s.

[0141] In step S4, the specific process conditions of hot rolling forming are: temperature of 110° C., pressure of 0.8 MPa, and time of 8 seconds.

[0142] In step S4, the specific conditions of the plasma treatment are: power 200 W, time 10 s.

[0143] In step S5, the specific process of gradient hot melt lamination is: preheating zone, temperature 100°C, time 3s; bonding zone, temperature 125°C, time 5s, pressure 0.08MPa; shaping zone, temperature 80°C, time 2s.

[0144] Example 2

[0145] The difference between this embodiment and embodiment 1 is that the surface layer is prepared using the first viscose fiber and the first ES fiber in a mass ratio of 2:1.

[0146] Comparative Example 1

[0147] The difference between this comparative example and Example 1 is that the raw material for preparing the surface layer is the first ES fiber.

[0148] Comparative Example 2

[0149] The difference between this comparative example and Example 1 is that the first ES fiber is PP skin layer / PE core layer, with a skin-core ratio of 3:7, a fineness of 1.4-1.6 dtex, and a length of 35-40 mm, and is from Hebei Jinyou New Material Technology Co., Ltd.

[0150] Comparative Example 3

[0151] The difference between this comparative example and Example 1 is that the guide layer only has an upper guide layer.

[0152] S2. Preparation of the guide layer: loosen and comb the raw materials of the upper guide layer into an upper fiber web, and send the web into a hot air penetration oven for reinforcement.

[0153] Comparative Example 4

[0154] The difference between this comparative example and Example 1 is that the second ES fiber is PP skin / PE core layer, the skin-core ratio is 2:3, the fineness is 5.8-6.2 dtex, and the length is 50-52 mm; the third ES fiber is PP skin / PE core layer, the skin-core ratio is 2:3, the fineness is 2.8-3.2 dtex, and the length is 35-40 mm; the fourth ES fiber is PP skin / PE core layer, the skin-core ratio is 2:3, the fineness is 1.4-1.6 dtex, and the length is 35-40 mm; all are from Hebei Jinyou New Material Technology Co., Ltd.

[0155] Comparative Example 5

[0156] The difference between this comparative example and Example 1 is that the core layer is prepared from raw materials of super absorbent resin and second viscose fiber in a mass ratio of 11:4.

[0157] Comparative Example 6

[0158] The difference between this comparative example and Example 1 is that the inorganic modifiers are halloysite nanotubes, montmorillonite and brucite fibers, with a mass ratio of 3:2:1.

[0159] Comparative Example 7

[0160] The difference between this comparative example and Example 1 is that the raw materials for preparing the superabsorbent resin, by weight, include 72 parts of acrylic acid, 12 parts of inorganic modifier, 1.5 parts of modified carboxymethyl chitosan, 1 part of crosslinking agent, 0.2 parts of initiator, and 90 parts of deionized water.

[0161] Performance Testing

[0162] The absorption rate and absorption rate of 3D sanitary napkins were tested with reference to GB / T 8939-2018, "Sanitary Napkins (Patent Liners)", with units of times and seconds, respectively. The rewet volume of 3D sanitary napkins was tested with reference to GB / T 28004.1-2021, "Diapers - Part 1: Infant Diapers", with units of grams. The test solution used was a simulated menstrual blood solution of 0.9% NaCl with a viscosity of 3.5 mPa·s. The results are shown in Table 1.

[0163] Table 1 Measurement results

[0164]

[0165] According to statistics, the 3D sanitary napkins based on viscose and ES fibers prepared in Examples 1-2 of the present invention have a short wetting time on the liquid-permeable surface, indicating rapid liquid absorption, improved dryness, high absorption rate, fast absorption speed, and low rewet. Comparative Example 1: The surface layer is made of only the first ES fiber; Comparative Example 2: The surface layer is made of the same fineness as the first viscose fiber; Comparative Example 3: The guide layer structure consists of only the upper guide layer; Comparative Example 4: The ES fibers used in the upper, middle, and lower guide layers are all concentric, i.e., have no eccentricity; Comparative Example 5: The core layer is made of no ES resin; Comparative Example 6: The inorganic modifiers are halloysite nanotubes, montmorillonite, and brucite fibers, i.e., these inorganic modifiers are not modified; Comparative Example 7: The superabsorbent resin is made of no acrylamide or sodium propylene sulfonate. The resulting 3D sanitary napkins have various deficiencies in performance. Therefore, the 3D sanitary napkin prepared using the raw materials and methods described in this application not only has a high absorption rate and a fast absorption speed, but also has a stable structure, low back-seepage volume, and is not easy for menstrual blood to back-seep, so the skin feels dry and non-sticky.

[0166] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A 3D sanitary napkin based on viscose and ES fiber, characterized by: The structure from top to bottom is surface layer, drainage layer, core layer, and bottom layer. The surface layer is made of first viscose fiber and first ES fiber. The first viscose fiber has a fineness of 1.4-1.6 dtex and a length of 35-40 mm. The first ES fiber is a PP skin layer / PE core layer with a skin-core ratio of 3:7, a fineness of 2.0-2.4 dtex, and a length of 50-52 mm. The guide layer comprises an upper guide layer, a middle guide layer and a lower guide layer; The upper guide layer is made of second ES fiber, which has a PP skin layer and a PE core layer with a skin-core ratio of 2:3, an eccentricity of 53%-57%, a crimp of 8-12 per 5cm, a fineness of 5.8-6.2 dtex, and a length of 50-52mm. The raw materials for the preparation of the middle-layer air distribution layer include third ES fiber; the third ES fiber is PP skin / PE core, with a skin-core ratio of 2:3, an eccentricity of 53%-57%, a crimp of 12-15 / 5cm, a fineness of 2.8-3.2dtex, and a length of 35-40mm; The lower guide layer is made of ES fiber; the ES fiber has a PP skin layer and a PE core layer with a skin-core ratio of 2:3, an eccentricity of 53%-57%, a crimp of 5-10 per 5cm, a fineness of 1.4-1.6 dtex, and a length of 35-40mm. The core layer is prepared from raw materials including super absorbent resin, fifth ES fiber and second viscose fiber; The raw materials for preparing the superabsorbent resin include, by weight, 60-65 parts of acrylic acid, 5-8 parts of acrylamide, 3-5 parts of sodium propylene sulfonate, 9-15 parts of an inorganic modifier, 1-2 parts of modified carboxymethyl chitosan, 0.8-1.2 parts of a crosslinking agent, 0.1-0.4 parts of an initiator, and 80-100 parts of deionized water; the inorganic modifier includes modified halloysite nanotubes, modified montmorillonite, and modified brucite fibers; The preparation method of modified halloysite nanotubes comprises: dispersing halloysite nanotubes in an ethanol aqueous solution with a mass fraction of 65%-75%, adding a silane coupling agent, refluxing at 80°C for 4 hours, centrifuging and washing until neutral, and drying to obtain the modified halloysite nanotubes.

2. A method for preparing a 3D sanitary napkin based on viscose and ES fiber according to claim 1, characterized in that: The following steps are involved: S1. Surface layer preparation: The first viscose fiber and the first ES fiber are mixed and opened, combed into a fiber web with fiber orientation, and then laid parallel to form a fiber web, which is then placed on a 3D embossing machine for hot rolling to obtain the fiber web; S2. Preparation of the guide layer: The raw materials of the upper guide layer, the middle guide layer, and the lower guide layer are loosened and combed into an upper fiber web, a middle fiber web, and a lower fiber web respectively; the middle fiber web is sent to an oven for hot air pre-bonding and then wave-formed to obtain a pre-treated middle fiber web; the pre-treated middle fiber web is superimposed with the upper fiber web and the lower fiber web, and then sent to a hot air through-drying oven for reinforcement. S3. Preparation of the core layer: hollow ES fibers and viscose staple fibers are opened and mixed with superabsorbent resin, which is then laid into a fiber web using an air-laid device. At the same time, SAP is gradient-distributed using a layered laying technique. The core layer is then microwave-treated and hot-rolled to form a fiber web. S4. Preparation of bottom layer: Lay the first ES fiber on the surface of PE film at a 45° angle, and control the surface density to 13-17 g / m 2 , after hot rolling and qualitative treatment, it is obtained by plasma treatment; S5. Preparation of three-dimensional sanitary napkin: stack the surface layer, the guide layer, the core layer and the bottom layer in order, and then perform gradient hot-melt compounding to obtain the sanitary napkin.

3. The preparation method according to claim 2, characterized in that In step S1, the surface density of the fiber web is 40-50 g / m 2 ; Alternatively, in step S1, the process conditions for hot rolling forming are: temperature of 130-140°C, pressure of 0.25-0.3 MPa, and time of 1-2 min.

4. The preparation method according to claim 2, characterized in that In step S2, the surface density of the upper fiber web is 25-30 g / m 2 ; Alternatively, in step S2, the surface density of the middle fiber web is 20-25 g / m 2 ; Alternatively, in step S2, the surface density of the lower fiber web is 15-20 g / m 2 .

5. The preparation method according to claim 2, characterized in that In step S3, the airflow speed is 15-20 m / s; Alternatively, in step S3, the surface density of the fiber web is 120-150 g / m 2 .

6. The preparation method according to claim 2, characterized in that In step S4, the process conditions for hot rolling forming are: temperature of 105-115° C., pressure of 0.7-1.0 MPa, and time of 6-10 s.

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