A motion-invariant core sanitary napkin and a method of making the same

Abstract

This invention discloses a sports-grade non-deformable core sanitary napkin, comprising, from bottom to top, a bottom film layer, a support layer, an absorbent layer, a diversion layer, and a skin-friendly layer. A method for preparing this sports-grade non-deformable core sanitary napkin includes the following steps: S1, raw material preparation; S2, gradient core preparation; S3, diversion frame integration; S4, three-dimensional composite; S5, edge reinforcement; S6, quality inspection and packaging. In this invention, by mixing short fibers and superabsorbent resin in a specific ratio in the upper layer, it can quickly respond to sudden menstrual flow, avoiding discomfort or leakage caused by liquid retention. Simultaneously, the lower layer of long fibers interwoven with superabsorbent resin forms a stable structure, maintaining a dry surface even after physical activity, reducing skin problems caused by moisture.

Description

Technical Field

[0001] This invention relates to the field of sanitary napkin technology, and in particular to a sanitary napkin with a non-deformable core during exercise and its preparation method. Background Technology

[0002] As an essential product for women during menstruation, the quality and user experience of sanitary napkins are of paramount importance. With modern women's increasing pursuit of health and quality of life, more and more women are participating in various sports activities during their periods.

[0003] Traditional sanitary napkins have significant structural defects in their absorbent layer during women's exercise. Their simple structure struggles to cope with the complex conditions the body encounters during exercise. Frequent movement and deformation during exercise subject the absorbent layer to forces in different directions, leading to uneven material distribution and reduced absorbency. Furthermore, the mixture of sweat and menstrual blood produced during exercise places higher demands on the absorbent layer's liquid handling capabilities. Traditional absorbent layers cannot efficiently process this mixture, easily resulting in side leakage and backflow, severely impacting women's experience and comfort during exercise.

[0004] Accordingly, this application proposes a sanitary napkin with a non-deformable core for movement and a method for preparing the same. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by proposing a non-deformable core sanitary napkin and its preparation method.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A non-deformable core sanitary napkin for sports and its preparation method, comprising, from bottom to top, a bottom film layer, a support layer, an absorbent layer, a diversion layer and a skin-friendly layer;

[0008] The bottom film layer has a sealed edge with the absorbent layer. The surface of the support layer has a recess that matches the bottom of the absorbent layer. The absorbent layer is a double-layer gradient core. The upper absorbent layer is a fast-absorbing layer made of short fibers mixed with superabsorbent resin, and the lower absorbent layer is a water-locking layer made of long fibers interwoven with superabsorbent resin. Columnar supports are evenly distributed between the upper and lower absorbent layers. The columnar supports penetrate vertically through the upper and lower absorbent layers. The surface of the flow-guiding layer is provided with flow-guiding grooves. The bottom surface of the flow-guiding layer is embedded with the fibers of the upper absorbent layer. The skin-friendly layer is connected to the flow-guiding layer through spaced adhesive dots.

[0009] Preferably, the edge of the absorbent layer is provided with a surrounding flow guide frame that is higher than the surface of the core. The surrounding flow guide frame is provided with an oblique flow guide channel, and the direction of the oblique flow guide channel of the surrounding flow guide frame is at an angle of 30°-60° with the longitudinal direction of the sanitary napkin.

[0010] Preferably, the top of the columnar support is embedded in the bottom surface of the guide layer, and the bottom of the guide layer and the recess of the support layer are provided with an movable gap.

[0011] Preferably, the support layer and the bottom film layer are connected by a mesh adhesive, and the support layer and the absorbent layer are locked together by adhesive dots around the support.

[0012] Preferably, the depth of the guide layer trench decreases from the edge to the center and forms a guide slope with a high edge and a low center with the surrounding guide frame.

[0013] A method for preparing a sanitary napkin with a non-deformable core during exercise includes the following steps:

[0014] S1. Raw material preparation: Prepare super absorbent resins with different properties. Select resins with small particle size and moderate liquid absorption ratio for the upper layer, and use resins with even smaller particle size and higher liquid absorption ratio for the lower layer. Combine these with hydrophilic fibers of different lengths and store them in proportion. Also prepare polyurethane elastomers as columnar supports, hydrophilic polymer materials to make a surrounding flow guide frame, and non-woven fabrics, membrane materials, and adhesive materials required for each layer.

[0015] S2. Gradient core preparation: Short fibers and superabsorbent resin are mixed evenly in a high-speed mixer according to a specific ratio. The mixture is then laid on a special mold by an automatic spreading device. During spreading, a low-frequency vibration device is activated to form a preliminary fast-absorbing layer. Using a high-precision injection device, polyurethane elastomer is injected into the preset position of the mold. Pressure is maintained to ensure that the support and the upper layer are tightly embedded. Long fibers and superabsorbent resin are mixed in another mixer and then laid on the upper layer and the support. The vibration frequency is increased to form a water-locking layer and promote fiber interweaving.

[0016] S3. The flow guide frame is integrated by using an extrusion molding machine to extrude hydrophilic polymer materials into a surrounding flow guide frame blank at a suitable temperature. The inclined flow guide channels are etched according to the design using laser etching equipment. Hot melt adhesive is applied to the edge of the absorption layer, and the molded frame is hot-pressed to ensure a firm connection between the frame and the absorption layer.

[0017] S4, three-dimensional composite: using positioning fixtures, the support layer membrane material with pits is covered on the bottom of the absorbent layer, so that the support body and the pits are precisely aligned. Glue is applied with dispensing equipment, leaving a gap for movement. The non-woven fabric guide layer with guide grooves is covered on the absorbent layer in the preset direction. The fibers of the two are interlocked by mechanical rolling device.

[0018] S5. Edge reinforcement: Using specialized edge cleaning equipment, excess material is removed and reshaped from the edges of the sanitary napkin. Ultrasonic welding equipment is used to weld the various layers of material at the edges according to appropriate parameters, forming a sealed edge that is higher than the core.

[0019] S6. Quality Inspection and Packaging: Combining manual visual inspection and machine vision inspection, check the appearance of sanitary napkins and the composite of each layer. Use high-precision instruments to measure dimensions and simulate usage scenarios to test absorption and leakage prevention performance. Qualified products are packaged using automated packaging equipment, ethylene oxide sterilization and vacuum packaging technology, and then labeled and boxed for warehousing or sale.

[0020] The present invention has the following beneficial effects:

[0021] 1. By mixing short fibers and super absorbent resin in a specific ratio in the upper layer, it can quickly cope with the sudden flow of menstrual blood, avoiding the risk of discomfort or leakage caused by fluid retention. At the same time, the long fibers in the lower layer interweave with super absorbent resin to form a stable structure, so that even after exercise and bumps, the surface can be kept dry, reducing skin problems caused by moisture.

[0022] 2. The absorbent layer edge is surrounded by a hydrophilic polymer frame with an internal angled flow channel that forms a 30°-60° angle with the sanitary napkin's longitudinal direction. This allows it to fit snugly against the body during exercise, effectively intercepting and diverting edge liquids for greater peace of mind.

[0023] 3. By setting columnar supports made of polyurethane elastomer evenly distributed between the upper and lower absorbent layers, penetrating vertically and fitting tightly, the sanitary napkin can maintain its shape after absorbing a large amount of liquid, and continue to perform its absorption and leak-proof functions. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the internal structure of a non-deformable core sanitary napkin proposed in this invention.

[0025] In the diagram: 1. Base film layer; 2. Support layer; 3. Absorbent layer; 4. Diversion layer; 5. Skin-friendly layer. Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0027] Reference Figure 1 A type of sanitary napkin with a non-deformable core for sports, comprising, from bottom to top, a bottom film layer 1, a support layer 2, an absorbent layer 3, a diversion layer 4, and a skin-friendly layer 5;

[0028] The bottom membrane layer 1 forms a sealed edge with the absorbent layer 3. The bottom membrane layer 1 is made of a composite of water-repellent non-woven fabric and PE breathable membrane. Its water-repellent non-woven fabric has a high level of water repellency, which can effectively prevent liquid from leaking out and ensure that the external environment is dry and clean. The sealed edge not only enhances the stability of the overall structure and prevents the contents of the absorbent layer 3 from being exposed, but also fits the body tightly during exercise, reducing edge friction, and further enhances the waterproof effect, eliminating the risk of side leakage.

[0029] The surface of the support layer 2 has recesses that fit the bottom of the absorption layer 3. The support layer 2 and the bottom membrane layer 1 are connected by a mesh adhesive, and the support layer 2 and the absorption layer 3 are locked by adhesive dots around the support. The support layer 2 is made of polyester elastic membrane material. These materials give the support layer 2 good elasticity and toughness, and can adapt to various dynamic changes of the body during exercise. The recesses designed on the surface, whether they are hexagonal, square or rhomboid arrays, have been precisely considered in terms of depth, diameter and spacing, and perfectly fit the bottom of the absorption layer 3. The presence of the recesses provides a precise positioning space for the bottom of the columnar support, and when the absorption layer 3 is under force, the recesses can buffer the pressure, disperse the force points and ensure the stability of the absorption layer 3 structure.

[0030] The absorbent layer 3 is a double-layer gradient core. The upper layer of the absorbent layer 3 is a fast-absorbing layer made of short fibers mixed with super absorbent resin, and the lower layer is a water-locking layer made of long fibers interwoven with super absorbent resin. The edge of the absorbent layer 3 is provided with a surrounding flow guide frame that is higher than the surface of the core. The surrounding flow guide frame has an oblique flow guide channel. The direction of the oblique flow guide channel of the surrounding flow guide frame is at an angle of 30°-60° with the longitudinal direction of the sanitary napkin. It can conform to the curve of the human body to the greatest extent during movement and effectively intercept the edge liquid. When the liquid flows to the edge, the oblique flow guide channel quickly guides the liquid to the center of the absorbent layer 3 to avoid liquid overflow and greatly reduce the risk of side leakage.

[0031] A columnar support is evenly distributed between the upper and lower layers of the absorbent layer 3. The columnar support penetrates vertically through the upper and lower layers of the absorbent layer 3. The columnar support is made of polyurethane elastomer and has suitable hardness and elasticity. After the absorbent layer 3 absorbs a large amount of liquid, it prevents the upper and lower layers from being excessively squeezed, which would cause the structure to collapse. It keeps the pores inside the absorbent layer 3 open and maintains good liquid transport and storage capacity.

[0032] The top of the columnar support is embedded in the bottom surface of the guide layer 4. The bottom of the guide layer 4 and the pit of the support layer 2 are reserved with an movable gap. The depth of the groove of the guide layer 4 decreases from the edge to the center and forms a guide slope with the edge high and the center low with the surrounding guide frame.

[0033] The surface of the flow-guiding layer 4 is provided with non-woven fabric with flow-guiding grooves. The depth of the grooves of the non-woven fabric decreases from the edge to the center, and forms a flow-guiding slope with the surrounding flow-guiding frame that is high at the edge and low at the center. When menstrual blood comes into contact with the flow-guiding layer 4, it is first intercepted by the grooves with higher edges, and then quickly converges to the center under the action of the slope, and is then efficiently absorbed by the absorbent layer 3. The bottom surface of the flow-guiding layer 4 is interlocked with the upper fiber of the absorbent layer 3, and the skin-friendly layer 5 is connected to the flow-guiding layer 4 through spacer adhesive dots.

[0034] A method for preparing a sanitary napkin with a non-deformable core during exercise includes the following steps:

[0035] S1. Raw material preparation: Prepare super absorbent resins with different properties. Select resins with small particle size and moderate liquid absorption ratio for the upper layer, and use resins with even smaller particle size and higher liquid absorption ratio for the lower layer. Combine these with hydrophilic fibers of different lengths and store them in proportion. Also prepare polyurethane elastomers as columnar supports, hydrophilic polymer materials to make a surrounding flow guide frame, and non-woven fabrics, membrane materials, and adhesive materials required for each layer.

[0036] S2. Gradient core preparation: Short fibers and superabsorbent resin are mixed evenly in a high-speed mixer according to a specific ratio. The mixture is then laid on a special mold using an automatic spreading device. During spreading, a low-frequency vibration device is activated to form a preliminary shape of the rapid absorption layer 3. Using a high-precision injection device, polyurethane elastomer is injected into the preset position of the mold. Pressure is maintained to ensure that the support and the upper layer are tightly embedded. Long fibers and superabsorbent resin are mixed in another mixer and then laid on the upper layer and the support. The vibration frequency is increased to form a water-locking layer and promote fiber interweaving.

[0037] S3. The flow guide frame is integrated by using an extrusion molding machine to extrude hydrophilic polymer materials into a surrounding flow guide frame blank at a suitable temperature. The inclined flow guide channels are etched according to the design using laser etching equipment. Hot melt adhesive is applied to the edge of the absorption layer 3, and the molded frame is hot-pressed to ensure a firm connection between the frame and the absorption layer 3.

[0038] S4. Three-dimensional composite: Using a positioning fixture, the support layer 2 membrane material with recesses is covered on the bottom of the absorbent layer 3, so that the support body and the recesses are precisely aligned. Glue is applied with a dispensing device, leaving a gap for movement. The non-woven fabric guide layer 4 with guide grooves is covered on the absorbent layer 3 in a preset direction. The fibers of the two are interlocked by a mechanical rolling device.

[0039] S5. Edge reinforcement: Using specialized edge cleaning equipment, excess material is removed and reshaped from the edges of the sanitary napkin. Ultrasonic welding equipment is used to weld the various layers of material at the edges according to appropriate parameters, forming a sealed edge that is higher than the core.

[0040] S6. Quality Inspection and Packaging: Combining manual visual inspection and machine vision inspection, check the appearance of sanitary napkins and the composite of each layer. Use high-precision instruments to measure dimensions and simulate usage scenarios to test absorption and leakage prevention performance. Qualified products are packaged using automated packaging equipment, ethylene oxide sterilization and vacuum packaging technology, and then labeled and boxed for warehousing or sale. Example 1:

[0041] Step 1: Raw material preparation. The bottom film layer is a 0.12mm thick water-repellent non-woven fabric composite PE breathable membrane. The water-repellent non-woven fabric has a water repellency level of 5, and the PE breathable membrane has an air permeability of 2200mm / s. The edges are ultrasonically welded to the absorbent layer to form a 3.5mm wide sealed edge.

[0042] The support layer is made of thermoplastic polyurethane elastomer with a thickness of 0.35 mm, a surface pit depth of 0.65 mm, a diameter of 1.2 mm, and the pits are distributed in a square array with a spacing of 2.5 mm, which is compatible with the bottom of the absorption layer.

[0043] The upper absorbent layer consists of short cotton fibers (2mm in length) mixed with superabsorbent resin (100μm particle size, 400 times absorption capacity) at a 6:4 mass ratio, with a thickness of 2mm. The lower water-locking layer consists of long nylon fibers (5.5mm in length) mixed with superabsorbent resin (65μm particle size, 510 times absorption capacity) at a 7:3 mass ratio, with a thickness of 3.2mm. The columnar support is made of polyurethane elastomer with a Shore A hardness of 58, with a diameter of 0.7mm and a height of 2.8mm, 70 of which are distributed per 10cm², vertically penetrating the upper and lower absorbent layers.

[0044] The flow-guiding layer is made of non-woven fabric with flow-guiding grooves on the surface. The groove depth is 0.13mm and the density is 10 strands / cm. The bottom surface and the upper fiber of the absorbent layer are interlocked through a needle punching process.

[0045] The skin-friendly layer is made of breathable and hydrophilic fabric with a thickness of 0.22mm, and is connected to the diversion layer by oval-shaped adhesive dots with a diameter of 2.5mm and a spacing of 20mm between the adhesive dots.

[0046] The surrounding flow guide frame is made of hydrophilic polyester material with a width of 4.5mm, an internal oblique flow guide channel with a diameter of 0.18mm, a density of 110 per cm, and the oblique flow guide channel is at a 50° angle to the longitudinal direction of the sanitary napkin and is 0.7mm higher than the core surface.

[0047] Step Two: Gradient Core Preparation. Short fibers and superabsorbent resin are mixed in a high-speed mixer at 1050 rpm for 13 minutes. The mixture is then spread onto a specially designed mold using an automated spreading device. During spreading, a low-frequency vibration device with a vibration frequency of 7 Hz is activated, and spreading continues for 13 minutes to form a preliminary rapid absorption layer. Using a high-precision injection molding machine, polyurethane elastomer is injected into the preset position of the mold at an injection pressure of 1.3 MPa and a temperature of 68°C, and held under pressure for 7 minutes to ensure a tight fit between the support and the upper layer. Long fibers and superabsorbent resin are mixed in another mixer at 850 rpm for 16 minutes, then spread onto the upper layer and support. The vibration frequency is increased to 9.5 Hz, and spreading continues for 16 minutes to form a water-locking layer and promote fiber interweaving.

[0048] Step 3: Integration of the flow guide frame. Using an extrusion molding machine, hydrophilic polyester material is extruded at 165℃ and an extrusion speed of 4.5mm / s to form a surrounding flow guide frame blank. The inclined flow guide channels are etched according to the design using laser etching equipment. 13g / m² of hot melt adhesive is applied to the edge of the absorbent layer. The molded frame is hot-pressed at 118℃ and 0.28MPa for 4.5 minutes to ensure a firm connection between the frame and the absorbent layer.

[0049] Step 4: Three-dimensional lamination. Using a positioning fixture, the support layer membrane material with recesses is placed over the bottom of the absorbent layer, ensuring precise alignment between the bottom of the support and the recesses. Adhesive is applied using a dispensing device, and after curing, a 0.25mm gap is maintained between the bottom of the support and the recesses. A non-woven fabric guide layer with drainage grooves is then placed over the absorbent layer in a predetermined direction. A mechanical rolling device is used to interlock the fibers of both layers at a rolling speed of 1.8m / min.

[0050] Step 5: Edge reinforcement. Use a vacuum suction cleaning device to remove excess material from the edges of the sanitary napkin and reshape it. Use an ultrasonic welding device with a welding power of 450W and a welding time of 0.8 seconds per weld point to weld the layers of material at the edge, forming a sealed edge that is 0.7mm higher than the core.

[0051] Step Six: Quality Inspection and Packaging. Combining manual visual inspection and machine vision inspection, check the appearance of the sanitary napkins and the composite of each layer. Use high-precision measuring instruments to measure the dimensions. Simulate usage scenarios to test absorption and leakage prevention performance. Qualified products are packaged using automated packaging equipment, ethylene oxide sterilization and vacuum packaging technology, and then labeled and boxed for warehousing or sale. Example 2:

[0052] Step 1: Raw material preparation. The bottom film layer uses a 0.1mm thick water-repellent non-woven fabric composite PE breathable membrane. The water-repellent non-woven fabric has a water repellency level of 4, and the air permeability of the PE breathable membrane is 2000mm / s. The edges of the bottom film layer and the absorbent layer are sealed with a width of 3mm through a hot pressing process.

[0053] The support layer is made of polyester elastomer material with a thickness of 0.3 mm. The surface pits are 0.6 mm deep and 1 mm in diameter. The pits are distributed in a regular hexagonal array with a spacing of 2 mm, which is compatible with the bottom of the absorbent layer.

[0054] The upper absorbent layer uses short viscose fibers with a length of 2.5 mm, mixed with superabsorbent resin with a particle size of 110 μm and an absorption ratio of 420 times at a mass ratio of 6:4, with a thickness of 2.2 mm. In the lower absorbent layer, the water-locking layer uses long polyester fibers with a length of 6 mm, mixed with superabsorbent resin with a particle size of 70 μm and an absorption ratio of 520 times at a mass ratio of 7:3, with a thickness of 3.3 mm. The columnar support is made of polyurethane elastomer with a Shore hardness of A55, with a diameter of 0.6 mm and a height of 2.5 mm. It is evenly distributed in the absorbent layer at a density of 60 per 10 cm², vertically penetrating the upper and lower absorbent layers.

[0055] The flow-guiding layer is made of non-woven fabric with flow-guiding grooves on the surface. The groove depth is 0.12mm and the density is 9 strands / cm. The bottom surface and the upper fiber of the absorbent layer are interlocked by mechanical rolling.

[0056] The skin-friendly layer is made of breathable and hydrophilic fabric with a thickness of 0.2mm, and is connected to the diversion layer by circular adhesive dots with a diameter of 2mm and a spacing of 18mm between the adhesive dots.

[0057] The surrounding flow guide frame is made of hydrophilic polypropylene material, with a width of 4mm and an internal oblique flow guide channel with a diameter of 0.15mm and a density of 100 per cm. The oblique flow guide channel is at a 45° angle to the longitudinal direction of the sanitary napkin and is 0.6mm higher than the core surface.

[0058] Step Two: Gradient Core Preparation. Short fibers and superabsorbent resin are mixed in a high-speed mixer at 1100 rpm for 12 minutes. The mixture is then spread onto a specially designed mold using an automated spreading device. During spreading, a low-frequency vibration device with a vibration frequency of 6 Hz is activated, and spreading continues for 12 minutes to form a preliminary rapid absorption layer. Using a high-precision injection molding machine, polyurethane elastomer is injected into the preset position of the mold at an injection pressure of 1.2 MPa and a temperature of 65°C, and held under pressure for 6 minutes to ensure a tight fit between the support and the upper layer. Long fibers and superabsorbent resin are mixed in another mixer at 900 rpm for 15 minutes, then spread onto the upper layer and support. The vibration frequency is increased to 9 Hz, and spreading continues for 15 minutes to form a water-locking layer and promote fiber interweaving.

[0059] Step 3: Integration of the flow-guiding frame. Using an extrusion molding machine, hydrophilic polypropylene material is extruded at 160℃ and an extrusion speed of 4mm / s to form a surrounding flow-guiding frame preform. Angled flow-guiding channels are etched according to the design using laser etching equipment. 12g / m² of hot melt adhesive is applied to the edge of the absorbent layer. The molded frame is then hot-pressed at 115℃ and 0.25MPa for 4 minutes to ensure a firm connection between the frame and the absorbent layer.

[0060] Step 4: Three-dimensional lamination. Using a positioning fixture, the support layer membrane material with recesses is placed over the bottom of the absorbent layer, ensuring precise alignment between the bottom of the support and the recesses. Adhesive is applied using a dispensing device, and after curing, a 0.2mm gap is left between the bottom of the support and the recesses. The non-woven fabric guide layer with drainage grooves is then placed over the absorbent layer in a predetermined direction. A mechanical rolling device is used to interlock the fibers of both layers at a rolling speed of 1.5m / min.

[0061] Step 5: Edge reinforcement. Use a brush roller cleaning device to remove excess material from the edges of the sanitary napkin and reshape it. Use an ultrasonic welding device with a welding power of 400W and a welding time of 0.7 seconds per weld point to weld the layers of material at the edge, forming a sealed edge that is 0.6mm higher than the core.

[0062] Step Six: Quality Inspection and Packaging. Combining manual visual inspection and machine vision, examine the appearance of the sanitary napkins and the composite structure of each layer. Dimensions are measured using high-precision measuring instruments, and absorption and leakage prevention performance are tested under simulated usage scenarios. Qualified products are packaged using automated packaging equipment, employing ethylene oxide sterilization and vacuum packaging technology. After labeling and boxing, they are ready for warehousing or sale. Example 3:

[0063] Step 1: Raw material preparation. The bottom film layer is a 0.08mm thick water-repellent non-woven fabric composite PE breathable membrane. The water-repellent non-woven fabric has a water repellency level of 3, and the PE breathable membrane has an air permeability of 1800mm / s. The edges are bonded to the absorbent layer with hot melt adhesive to form a 2.5mm wide sealed edge.

[0064] The support layer is made of styrene-butadiene-styrene block copolymer elastomer with a thickness of 0.25 mm, a surface pit depth of 0.5 mm, a diameter of 0.8 mm, and the pits are distributed in a diamond array with a spacing of 1.8 mm, which is compatible with the bottom of the absorbent layer.

[0065] The upper absorbent layer consists of 3mm long modal fibers mixed with a 120μm particle size and a 430x absorption ratio superabsorbent resin at a 6:4 mass ratio, with a thickness of 2.4mm. The lower water-locking layer consists of 6.5mm long acrylic fibers mixed with a 75μm particle size and a 530x absorption ratio superabsorbent resin at a 7:3 mass ratio, with a thickness of 3.5mm. The columnar support is made of polyurethane elastomer with a Shore A hardness of 52, with a diameter of 0.5mm and a height of 2.3mm, 55 of which are distributed per 10cm², vertically penetrating the upper and lower absorbent layers.

[0066] The surface of the flow-guiding layer is made of non-woven fabric with flow-guiding grooves. The groove depth is 0.11 mm and the density is 8 fibers / cm. The bottom surface is interlocked with the upper fiber of the absorbent layer through a chemical bonding process.

[0067] The skin-friendly layer is made of breathable and hydrophilic fabric with a thickness of 0.18mm, and is connected to the diversion layer by triangular adhesive dots with a diameter of 1.8mm and a spacing of 16mm between the adhesive dots.

[0068] The surrounding flow guide frame is made of hydrophilic polyamide material, with a width of 3.5mm and an internal oblique flow guide channel with a diameter of 0.13mm and a density of 90 per cm. The oblique flow guide channel is at a 35° angle to the longitudinal direction of the sanitary napkin and is 0.5mm higher than the core surface.

[0069] Step Two: Gradient Core Preparation: Short fibers and superabsorbent resin are mixed in a high-speed mixer at 1150 rpm for 11 minutes. The mixture is then spread onto a specially designed mold using an automatic spreading device. During spreading, a low-frequency vibration device with a vibration frequency of 5 Hz is activated, and spreading continues for 11 minutes to form a preliminary rapid absorption layer. Using a high-precision injection molding machine, polyurethane elastomer is injected into the preset position of the mold at an injection pressure of 1.1 MPa and a temperature of 62°C, and held under pressure for 5 minutes to ensure a tight fit between the support and the upper layer. Long fibers and superabsorbent resin are mixed in another mixer at 950 rpm for 14 minutes, then spread onto the upper layer and the support. The vibration frequency is increased to 8.5 Hz, and spreading continues for 14 minutes to form a water-locking layer and promote fiber interweaving.

[0070] Step 3: Integration of the flow guide frame: Using an extrusion molding machine, hydrophilic polyamide material is extruded at 155℃ and an extrusion speed of 3.5mm / s to form a surrounding flow guide frame preform. Angled flow guide channels are etched according to the design using laser etching equipment. 11g / m² of hot melt adhesive is applied to the edge of the absorber layer. The molded frame is then hot-pressed at 112℃ and 0.22MPa for 3.5 minutes to ensure a firm connection between the frame and the absorber layer.

[0071] Step 4: Three-dimensional lamination: Using a positioning fixture, the support layer membrane material with recesses is placed over the bottom of the absorbent layer, ensuring precise alignment between the bottom of the support and the recesses. Adhesive is applied using a dispensing device, and after curing, a 0.15mm gap is maintained between the bottom of the support and the recesses. The non-woven fabric guide layer with drainage grooves is then placed over the absorbent layer in a predetermined direction. A mechanical rolling device is used to interlock the fibers of both layers at a rolling speed of 1.2m / min.

[0072] Step 5: Edge reinforcement: Use a brush roller cleaning device to remove excess material from the edges of the sanitary napkin and reshape it. Use an ultrasonic welding device with a welding power of 350W and a welding time of 0.6 seconds per weld point to weld the layers of material at the edge, forming a sealed edge that is 0.5mm higher than the core.

[0073] Step Six: Quality Inspection and Packaging: Combining manual visual inspection and machine vision inspection, examine the appearance of the sanitary napkins and the composite structure of each layer. Measure dimensions using high-precision measuring instruments and simulate usage scenarios to test absorption and leakage prevention performance. Qualified products are packaged using automated packaging equipment, employing ethylene oxide sterilization and vacuum packaging technology. After labeling and boxing, they are ready for warehousing or sale.

[0074] It should be noted that, in order to fully verify the performance advantages of the sports-resistant core sanitary napkin compared with traditional sanitary napkins in different sports scenarios, 15 female volunteers were recruited to conduct tests on three common sports: rope skipping, yoga, and running. The test subjects were the sports-resistant core sanitary napkins prepared in Examples 1, 2, and 3, as well as Comparative Examples 1 and 2. Comparative Example 1 used traditional non-woven sanitary napkins, while Comparative Example 2 used a softer non-woven fabric. All were tested uniformly.

[0075] In the 10-minute jump rope test, volunteers using sanitary napkins from Example 1 absorbed approximately 1080 grams of menstrual blood in 10 minutes, with most volunteers reporting consistently good absorption. Volunteers using sanitary napkins from Example 2 absorbed approximately 1000 grams of menstrual blood in 10 minutes. Although the absorption rate was slightly lower than Example 1, it still effectively handled menstrual flow and maintained a dry surface. Volunteers using sanitary napkins from Example 3 absorbed approximately 1020 grams of menstrual blood in 10 minutes, quickly absorbing large amounts of menstrual blood. Volunteers using Comparative Example 1 absorbed approximately 480 grams of menstrual blood in 10 minutes. As the jump rope time increased, the absorption rate gradually lagged behind the flow rate, resulting in noticeable liquid accumulation on the surface. Volunteers using Comparative Example 2 absorbed approximately 720 grams of menstrual blood in 10 minutes, and the shortcomings in absorption performance gradually became apparent during the jump rope test, as detailed in Table 1.

[0076] Table 1: Comparison of absorbency, leak-proofness, and breathability among 15 volunteers after rope skipping tests.

[0077] Serial Number Absorption capacity (g) in 10 minutes Leakage prevention capability (%) Breathability (%) Example 1 1080g 80% 60% Example 2 1000g 60% 40% Example 3 1020g 750% 50% Comparative Example 1 480g 20% 20% Comparative Example 2 720g 40% 40%

[0078] It should be noted that Example 1 has a side leakage prevention rate of 80%, which is significantly higher than Comparative Example 1's 20% and Comparative Example 2's 40%, and also better than Example 2's 60%. This higher side leakage prevention rate means that menstrual blood is less likely to leak from the edges of the sanitary napkin during rope skipping, providing women with more reliable protection, avoiding the embarrassment of side leakage, and allowing women to exercise with greater peace of mind.

[0079] Example 1 has a breathability of 60%, which is significantly higher than Comparative Example 1's 20%, and also better than Comparative Example 2 and Example 2's 40%. Good breathability allows air to circulate better between the sanitary napkin and the skin. When jumping rope, women sweat a lot, and good breathability can effectively reduce stuffiness and dampness, keep the private parts dry and comfortable, reduce skin discomfort and infection risk caused by a damp environment, and improve the exercise experience during menstruation.

[0080] It should be noted that in the 1-hour yoga class test, the sanitary napkin of Example 1 achieved an absorption rate of 97%. Its double-layer gradient absorption layer quickly absorbed menstrual blood in various postures, while the lower water-locking layer effectively prevented backflow, ensuring stable absorption. The sanitary napkin of Example 2 achieved an absorption rate of approximately 95%. Its stable absorption layer structure adapted to changes in yoga postures, quickly absorbing menstrual blood while maintaining good water-locking performance, providing users with a continuously dry experience. The sanitary napkin of Example 3 achieved an absorption rate of 93%, efficiently absorbing menstrual blood in different yoga postures and maintaining a high absorption rate. The sanitary napkin of Comparative Example 1 showed uneven absorption due to posture changes, resulting in an overall absorption rate of approximately 85%. The sanitary napkin of Comparative Example 2 achieved an absorption rate of 90% in some specific postures, as shown in Table 2.

[0081] Table 2: Comparison of absorption rate, reabsorption volume, and comfort level among 15 volunteers after 1 hour of yoga practice.

[0082] Serial Number Absorption rate (%) Recirculation volume (g) Comfort level (%) Example 1 97% 3.5g 60% Example 2 95% 3.8g 50% Example 3 93% 3.5g 55% Comparative Example 1 85% 7.2g 20% Comparative Example 2 90% 8.5g 40%

[0083] It should be noted that the absorption rate of Example 1 reached 97%, which is higher than that of Example 2 (95%) and Example 3 (93%), and far exceeds that of Comparative Example 1 (85%), and is also higher than that of Comparative Example 2 (90%). This indicates that Example 1 can absorb menstrual blood more efficiently. Under the same test conditions, it can absorb and lock more menstrual blood within the sanitary napkin, effectively reducing the risk of leakage due to insufficient absorption and providing users with more reliable absorption protection, especially when menstrual flow is heavy, the advantage is more obvious.

[0084] Regarding the amount of rewetting, Example 1 showed 3.5g, lower than Example 2's 3.8g, the same as Example 3, and significantly lower than Comparative Example 1's 7.2g and Comparative Example 2's 8.5g. The lower rewetting amount means that after menstrual blood is absorbed, less will seep back onto the sanitary napkin surface, keeping the surface dry and avoiding dampness and discomfort caused by rewetting. This greatly improves comfort and hygiene during use, reduces prolonged skin contact with menstrual blood, and lowers the risk of infection.

[0085] The comfort level of Example 1 is 60%, higher than 50% of Example 2 and 55% of Example 3, significantly higher than 20% of Comparative Example 1, and also higher than 40% of Comparative Example 2. Comfort level comprehensively reflects multiple factors such as the material, fit, and breathability of the sanitary napkin. The higher comfort level indicates that Example 1 performs excellently in these aspects, providing users with a better experience during use. Whether in daily activities or exercise, it allows users to feel more comfortable and reduces discomfort caused by improper use of sanitary napkins.

[0086] In a 30-minute running test, volunteers using sanitary napkins of Example 1 achieved an average absorption rate of 12 grams per minute within 30 minutes. The absorbent layer quickly absorbed menstrual blood, keeping the surface dry, and the absorption speed was stable, effectively coping with the continuous flow of menstrual blood during running. Volunteers using sanitary napkins of Example 2 achieved an average absorption rate of 10 grams per minute within 30 minutes. Although the absorption rate was slightly lower than that of Example 1, it was still sufficient to meet the menstrual blood absorption needs during running. Volunteers using sanitary napkins of Example 3 achieved an average absorption rate of 9.5 grams per minute within 30 minutes. They also quickly absorbed menstrual blood and kept the surface dry during running. Volunteers using sanitary napkins of Comparative Example 1 achieved an average absorption rate of 6 grams per minute within 30 minutes. The absorption speed could not keep up with the flow of menstrual blood, and the surface felt noticeably damp. Volunteers using sanitary napkins of Comparative Example 2 achieved an average absorption rate of 8 grams per minute within 30 minutes, indicating poor absorption performance. Details are shown in Table 3.

[0087] Table 3: Comparison of Absorption, Flexibility, and Antibacterial Properties among 15 Volunteers During a 30-Minute Run

[0088] Serial Number Absorption rate (g / min) Flexibility (%) Antibacterial properties (%) Example 1 12g / min 75% 80% Example 2 10g / min 70% 70% Example 3 9.5g / min 73% 75% Comparative Example 1 6g / min 50% 50% Comparative Example 2 8g / min 60% 60%

[0089] It should be noted that, in terms of flexibility, Example 1 has a flexibility of 75%, which is higher than Example 2's 70% and Example 3's 73%, and also significantly higher than Comparative Example 1's 50% and Comparative Example 2's 60%. A sanitary napkin with good flexibility can better conform to the body's curves during use, reducing discomfort caused by a poor fit during daily activities or exercise, improving user comfort, and also reducing the possibility that bending or twisting will affect the absorbency and leak-proof performance of the sanitary napkin.

[0090] The antibacterial performance of Example 1 is 80%, which is higher than that of Example 2 (70%), Example 3 (75%), Comparative Example 1 (50%), and Comparative Example 2 (60%). Higher antibacterial performance can effectively inhibit bacterial growth, reduce odor and infection risks caused by bacterial proliferation, provide healthier hygiene protection for women during menstruation, and help maintain a clean and healthy environment for the private parts.

[0091] Overall, the sanitary napkin of Embodiment 1 of this invention exhibits significant advantages in many aspects. In terms of absorption, it can quickly and efficiently absorb menstrual blood, whether during daily life or exercise, reducing leakage and the frequency of changing. It has excellent anti-leakage capabilities and can firmly lock in blood during activities such as yoga, running, and skipping rope. It has good flexibility, conforms to the body's curves, has good breathability, and is comfortable to use. Its antibacterial properties are also outstanding, inhibiting bacteria and creating a safe environment for the private parts. It provides comprehensive care for women during menstruation and brings users a higher quality, healthier, and more comfortable user experience.

[0092] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A sanitary napkin with a non-deformable core during exercise, characterized in that, From bottom to top, it includes a base film layer (1), a support layer (2), an absorbent layer (3), a diversion layer (4), and a skin-friendly layer (5). The bottom film layer (1) forms a sealed edge with the absorbent layer (3). The surface of the support layer (2) is provided with a pit that matches the bottom of the absorbent layer (3). The absorbent layer (3) is a double-layer gradient core. The upper layer of the absorbent layer (3) is a quick-absorbing layer of short fiber mixed with super absorbent resin. The short fiber is made of cotton fiber. The mass ratio of the short fiber to the super absorbent resin is 6:

4. The lower layer of the absorbent layer (3) is a water-locking layer of long fiber interwoven with super absorbent resin. The long fiber is made of nylon fiber. The mass ratio of the long fiber to the super absorbent resin is 7:

3. The quick-absorbing layer and the lower layer of the water-locking layer are uniformly distributed with columnar supports made of polyurethane elastomer. The columnar supports penetrate vertically through the upper and lower layers of the absorbent layer (3). The surface of the flow-guiding layer (4) is provided with non-woven fabric with flow-guiding grooves. The bottom surface of the flow-guiding layer (4) is embedded with the upper fiber of the absorbent layer (3). The skin-friendly layer (5) is connected to the flow-guiding layer (4) through spacer adhesive dots. The edge of the absorbent layer (3) is provided with a surrounding flow-guiding frame that is higher than the core surface. The surrounding flow-guiding frame is provided with an oblique flow-guiding channel. The direction of the oblique flow-guiding channel of the surrounding flow-guiding frame is at an angle of 30°-60° with the longitudinal direction of the sanitary napkin.

2. The sanitary napkin with a non-deformable core according to claim 1, characterized in that, The top of the columnar support is embedded in the bottom surface of the guide layer (4), and the bottom of the guide layer (4) and the recess of the support layer (2) are reserved with an movable gap.

3. A sanitary napkin with a non-deformable core according to claim 2, characterized in that, The support layer (2) and the bottom film layer (1) are connected by a mesh adhesive, and the support layer (2) and the absorbent layer (3) are locked by adhesive dots around the columnar support.

4. A sanitary napkin with a non-deformable core according to claim 2, characterized in that, The depth of the guide layer (4) decreases from the edge to the center and forms a guide slope with a high edge and a low center with the surrounding guide frame.

5. A method for preparing a sports-resistant, non-deformable core sanitary napkin as described in any one of claims 1-4, characterized in that, Includes the following steps: S1. Raw material preparation: Prepare super absorbent resins with different properties. Select resins with small particle size and moderate liquid absorption ratio for the upper layer, and use resins with even smaller particle size and higher liquid absorption ratio for the lower layer. Combine these with hydrophilic fibers of different lengths and store them in proportion. Also prepare polyurethane elastomers as columnar supports, hydrophilic polymer materials to make a surrounding flow guide frame, and non-woven fabrics, membrane materials, and adhesive materials required for each layer. S2, Gradient core preparation: short fibers and super absorbent resin are mixed evenly in a high-speed mixer according to a specific ratio, and then laid on a special mold by an automatic material laying device. When laying the material, the low-frequency vibration device is turned on to form a rapid absorption layer (3) prototype. With the help of a high-precision injection device, polyurethane elastomer is injected into the preset position of the mold and pressure is maintained to make the support and the upper layer tightly embedded. After the long fibers and super absorbent resin are mixed in another mixer, they are laid on the upper layer and the support to increase the vibration frequency, form a water-locking layer and promote fiber interweaving. S3. The flow guide frame is integrated. The hydrophilic polymer material is extruded into a circular flow guide frame blank at a suitable temperature using an extrusion molding machine. The oblique flow guide channel is etched according to the design using a laser etching equipment. Hot melt adhesive is applied to the edge of the absorption layer (3). The molded frame is hot-pressed to ensure that the frame and the absorption layer (3) are firmly connected. S4, three-dimensional composite, by using positioning fixtures, the support layer (2) membrane material with pits is covered on the bottom of the absorbent layer (3), so that the support body and the pits are precisely aligned, glue is applied with dispensing equipment, and a gap is reserved for movement. The non-woven fabric guide layer (4) with guide grooves is covered on the absorbent layer (3) in the preset direction, and the fibers of the two are interlocked by mechanical rolling device. S5. Edge reinforcement: Using a special edge cleaning device, excess material is removed and shaped from the edge of the sanitary napkin. Ultrasonic welding equipment is used to weld the edge material according to appropriate parameters to form a sealed edge that is higher than the core. S6. Quality Inspection and Packaging: Combining manual visual inspection and machine vision inspection, check the appearance of sanitary napkins and the composite of each layer. Use high-precision instruments to measure dimensions and simulate usage scenarios to test absorption and leakage prevention performance. Qualified products are packaged using automated packaging equipment, ethylene oxide sterilization and vacuum packaging technology, and then labeled and boxed for warehousing or sale.

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