Equipment and method for detecting water locking performance of nursing pad

Abstract

The invention discloses a device and method for detecting the water locking performance of a nursing pad, and relates to the field of material performance tests.The detection method comprises the following steps that S1, a nursing pad sample is fixed to a detection platform, a composite dynamic pressure sequence containing sine fluctuation, stepped pressurization and random disturbance is applied, constant-temperature liquid is injected into the sample synchronously, and the water locking amount is calculated; s2, scanning the three-dimensional distribution of liquid in real time, capturing the expansion state of a core body, triggering sudden stop when the edge leaks, and calculating the water locking efficiency; s3, taking an absorption core material, soaking the absorption core material in normal saline, performing centrifugal dewatering, and calculating the water retention capacity; and S4, constructing a three-level evaluation system output performance report. Composite multi-point pressure is adopted to simulate human body activity mechanics characteristics, a multi-mode sensing technology is combined to track the liquid three-dimensional permeation process in real time, the defects that a traditional method is single in pressure and insufficient in detection dimension are overcome, and dynamic process analysis support which cannot be achieved through traditional static detection is provided for product optimization.

Description

Technical Field

[0001] The present invention relates to the technical field of material performance testing, and particularly to nursing pads, specifically a nursing pad water locking performance detection device and method. Background Art

[0002] In modern society, with the aggravation of the aging population problem and the improvement of people's attention to personal hygiene care, as an important sanitary product, the market demand for nursing pads is increasing day by day. The common structure of a nursing pad is that the surface layer uses skin-friendly non-woven fabric, the bottom layer uses a PE film with better barrier effect, and the absorbent core body composed of superabsorbent resin is compounded between the two. Its main function is to quickly absorb and lock liquids such as urine and blood, keep the user's skin dry, and prevent skin problems such as diaper rash. Therefore, the water locking performance of nursing pads becomes one of the key indicators to measure their quality.

[0003] Currently, in the process of testing the water locking performance of nursing pads by traditional detectors, the static weight pressing method is generally adopted, and a fixed weight is applied on the surface of the sample to simulate the pressure. However, the pressure generated by the human body during actual use is dynamically changing (such as the amplitude and frequency of the pressure fluctuate due to actions such as turning over and sitting up), and the static pressing cannot reproduce this complex mechanical environment.

[0004] Therefore, there are obvious deficiencies in the traditional detection method for evaluating the water locking performance of nursing pads, and a more scientific and accurate detection method is urgently needed. Summary of the Invention

[0005] The present invention overcomes the deficiencies of the prior art and provides a nursing pad water locking performance detection device and method.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is: a nursing pad water locking performance detection method, applicable to the water locking performance detection of nursing pads with superabsorbent resin of starch graft copolymerized with acrylic acid or acrylamide monomer as the absorbent core body material, including the following steps: S1. Fix the nursing pad sample on the detection platform, apply a composite dynamic pressure sequence including sine wave fluctuation, stepwise pressure increase and random perturbation, and simultaneously inject a constant temperature liquid into the sample to calculate the water locking amount; S2. Real-time scan the three-dimensional distribution of the liquid through a capacitance sensor matrix, combine hyperspectral imaging to capture the swelling state of the core body, trigger an emergency stop when edge leakage is detected, and calculate the water locking efficiency; S3. Take the absorbent core body material, soak it in physiological saline for 30 minutes and then centrifuge to dehydrate, and calculate the water retention amount; S4. Based on the water locking amount, water locking efficiency, water retention amount and back leakage index, construct a three-level evaluation system to output a performance report.

[0007] In a preferred embodiment of the present invention, in the step of S1, the dynamic pressure sequence includes: t = 0 - 30 s: sinusoidal wave pressure 5 ± 2 kPa, frequency 1 Hz; t = 30 - 60 s: stepped pressure increase from 10 kPa to 25 kPa to 40 kPa, with each step of pressure increase lasting for 10 s; t = 60 - 90 s: white noise random pressure 0 - 15 kPa.

[0008] In a preferred embodiment of the present invention, in the step of S1, the calculation formula for the water-locking capacity is: ; Wherein, is the water-locking capacity; is the injection rate; is the real-time leakage rate; is the total test duration; is the time element.

[0009] In a preferred embodiment of the present invention, in the step of S2, the capacitance sensor matrix has a 256-point distributed layout, with a spacing of 5 mm, a sensitivity of 0.1 μl, and a data acquisition frequency of 100 ms / time; the hyperspectral imaging frame rate is 60 fps, and the wavelength resolution is 5 nm; the calculation formula for the water-locking efficiency is: ; Wherein, is the water-locking efficiency; is the maximum water-locking capacity; is the effective absorption area; is the time to reach the maximum water-locking capacity.

[0010] In a preferred embodiment of the present invention, in the step of S3, the centrifugation condition is centrifugal dehydration at 250 g for 3 min; the calculation formula for the water retention capacity is: ; Wherein, is the water retention capacity; is the dry weight of the sample; is the total mass of the sample + tea bag after dehydration; is the mass of the blank tea bag after dehydration.

[0011] In a preferred embodiment of the present invention, in the step of S4, the three-level evaluation system includes: Level I indicators: absorption rate, maximum water-locking capacity, water retention capacity; Level II indicators: water-locking stability under pressure disturbance, backflow index; Level III indicators: critical failure pressure, leakage risk coefficient; Verify the seepage rate by modifying the Darcy equation.

[0012] In a preferred embodiment of the present invention, the calculation formula for the back-seepage index is: ; Wherein, is the back-seepage index; is the initial dry weight; is the weight after pressure release; The calculation formula for the leakage risk coefficient is: ; Wherein, is the leakage risk coefficient; is the total leakage amount during the whole testing process; is the maximum water-locking capacity; The modified Darcy equation is: ; Wherein, is the liquid seepage velocity; is the material permeability; is the liquid viscosity; is the pressure gradient; is the liquid density; is the acceleration due to gravity; is the material strain correction term, and its calculation formula is: ; Wherein, , ; is the material compressive strain, , is the thickness compression amount, is the initial thickness.

[0013] The present invention provides a detection device for detecting the water-locking performance of a nursing pad, including: a device frame, a detection table, a fixing frame installed on the top of the device frame, and a control system for automatically detecting the water-locking performance of the nursing pad by using a controller; A sample groove is formed on the top of the detection table, and a clamping mechanism for fixing the nursing pad sample is installed on the detection table; a hydraulic cylinder is fixed on the top of the fixing frame, a pressing plate is arranged at the bottom of the hydraulic cylinder, and a connection limiting mechanism for transmitting the feeding amount of the hydraulic cylinder is arranged between the hydraulic cylinder and the pressing plate; A plurality of pull rod cylinders are installed on the pressing plate, a pressing head is fixed at the output end of the pull rod cylinder located at the bottom of the pressing plate, and a plurality of hyperspectral cameras are installed on the side surface of the pressing plate; A plurality of capacitance sensors and a plurality of liquid outlets are installed at the bottom of the pressing plate. A liquid injection flow channel is opened inside the pressing plate. A liquid infusion head for externally connecting an infusion device to supply a test solution is fixed on the side surface of the pressing plate.

[0014] In a preferred embodiment of the present invention, the clamping mechanism includes: a plurality of threaded holes opened at the top of the detection table, adjusting bolts threadedly connected inside the threaded holes, and connecting blocks rotatably connected to the sides of the adjusting bolts; a pressing piece is fixed at the bottom of the connecting block.

[0015] In a preferred embodiment of the present invention, the connection and limiting mechanism includes: a plurality of connecting rods fixed on the top of the pressing plate, and a connection frame fixed between the plurality of connecting rods; the top of the connection frame is fixed to the output end of the hydraulic cylinder, and the sides of the plurality of connecting rods are sleeved inside the fixed frame.

[0016] The present invention solves the defects existing in the background technology, and the present invention has the following beneficial effects: (1) The present invention provides a nursing pad water lock performance detection device and method. Through the coordinated control of dynamic pressure loading and liquid perfusion, the authenticity and accuracy of the nursing pad water lock performance detection are significantly improved. The composite multi-point pressure is used to simulate the mechanical characteristics of human activities, and the multi-modal sensing technology is combined to track the three-dimensional liquid penetration process in real time, overcoming the defects of single pressure and insufficient detection dimensions of traditional methods. And through an intelligent algorithm, a comprehensive evaluation system is constructed by integrating multiple parameters such as leakage risk coefficient and re-infiltration volume, improving the detection accuracy to the micro-liter level, and at the same time generating a visual penetration cloud map and material failure warning data, providing dynamic process analysis support for product optimization that cannot be achieved by traditional static detection.

[0017] (2) In the present invention, a new evaluation system with water lock efficiency as the core, through simulating human activities with a dynamic pressure sequence, combining liquid perfusion and multi-modal sensing technology, tracks the penetration behavior of materials under real pressure in real time, and then expands the single index of short-term absorption amount into a dynamic model of water lock efficiency, quantifying the water lock ability per unit time and per unit area, fundamentally solving the problem of misjudgment of the performance of starch-based resins due to slow water absorption, and providing technical support for the accurate evaluation of environmental protection materials.

[0018] (3) In the present invention, by constructing a three-level index system including basic performance, dynamic performance and safety performance, and introducing a strain correction term into the traditional Darcy equation, the influence of the blockage of the pores in the core under compressive strain of the material on the penetration speed is quantified. When the material is compressed to the critical deformation, the system automatically triggers a failure warning, so as to facilitate guiding the design of the anti-compression structure of the product. Description of the Drawings

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments recorded in the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings; Figure 1 is a three-dimensional structure diagram of the water-locking performance detection device for the nursing pad in the preferred embodiment of the present invention; Figure 2 is a schematic diagram of the distribution of several pull rod cylinders in the preferred embodiment of the present invention; Figure 3 is a schematic diagram of the distribution of several pressing heads and its partial enlarged view in the preferred embodiment of the present invention; Figure 4 is a separation structure diagram of the adjusting bolt and the threaded hole in the preferred embodiment of the present invention; In the figure: 1, equipment frame; 2, detection table; 21, specimen groove; 3, fixing frame; 4, control system; 5, hydraulic cylinder; 51, pressing plate; 52, pull rod cylinder; 53, pressing head; 54, hyperspectral camera; 55, capacitance sensor; 56, liquid outlet head; 57, liquid infusion head; 6, threaded hole; 61, adjusting bolt; 62, connecting block; 63, pressing piece; 7, connecting rod; 71, connecting frame. Detailed implementation manners

[0020] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0021] In the following description, many specific details are set forth to fully understand the present invention. However, the present invention can also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited by the specific embodiments disclosed below.

[0022] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "top", "bottom", "inside", "outside", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the scope of protection of the present application. In the description of the present invention, unless otherwise specified, the meaning of "several" is two or more.

[0023] In the description of this application, it should be noted that unless otherwise clearly specified and defined, the terms "installation", "setting", and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific situations.

[0024] Application Overview: After in-depth analysis of the actual usage scenarios of nursing pads by the applicant, it is found that the national standard test method has serious deficiencies in the adaptability to new environmentally friendly materials.

[0025] Specifically, starch-based resin, that is, the graft copolymer of starch and monomers such as acrylic acid and acrylamide (such as starch-acrylic acid graft resin), as an environmentally friendly material, has a medium water absorption capacity due to its unique chemical structure and is particularly suitable for mild electrolyte solution environments, such as nursing pads designed for people with allergies or environmental protection needs.

[0026] The applicant found that under the test framework of the current national standard GB / T 22875-2018 "High Absorbency Resins for Diapers and Sanitary Napkins", for the detection logic of the absorbent core material - polyacrylate resin, it depends on the performance detection of the short-time absorption amount. However, when simulating the real usage environment of the nursing pad, the starch-based resin shows obvious water absorption hysteresis due to the molecular structure characteristics. Its 30-second absorption amount is significantly lower than that of polyacrylic acid resin, but the saturated water locking capacity is close to the latter level. Furthermore, it cannot reach the saturated state within the short time specified by the national standard, resulting in a low measured absorption speed and unable to truly reflect its water locking performance in actual use. Thus, it shows that the traditional "absorption speed" index cannot objectively evaluate the performance advantages of starch-based resin and instead misleads product design.

[0027] To address the above problems, the applicant proposed a nursing pad water locking performance detection device and method, a new evaluation system with water locking efficiency as the core. By simulating human activities through a dynamic pressure sequence, combining liquid perfusion and multimodal sensing technologies, it can track the penetration behavior of materials under real pressure in real time. Furthermore, it expands the single index of short-time absorption amount into a dynamic water locking efficiency model to quantify the water locking ability per unit time and unit area, fundamentally solving the problem of performance misjudgment caused by the slow water absorption of starch-based resin and providing technical support for the accurate evaluation of environmentally friendly materials.

[0028] A method for detecting the water locking performance of a nursing pad, which is applicable to the detection of the water locking performance of a nursing pad with an absorbent core material made of an absorbent resin obtained by graft copolymerizing starch with acrylic acid or acrylamide monomers, includes the following steps: S1. Fix the nursing pad specimen on the testing platform, apply a composite dynamic pressure sequence including sinusoidal fluctuations, stepped pressure increases, and random perturbations, and simultaneously inject a constant-temperature liquid into the specimen to calculate the water-locking capacity; S2. Real-time scan the three-dimensional liquid distribution through a capacitance sensor matrix, capture the swelling state of the core by combining hyperspectral imaging, trigger an emergency stop when edge leakage is detected, and calculate the water-locking efficiency; S3. Take the absorbent core material, soak it in physiological saline for 30 minutes and then centrifuge to dehydrate, and calculate the water retention capacity; S4. Based on the water-locking capacity, water-locking efficiency, water retention capacity, and re-infiltration index, construct a three-level evaluation system to output a performance report.

[0029] In some specific embodiments, in the step of S1, it specifically includes the following sub-steps: S11. Apply a sinusoidal fluctuating pressure of 5 ± 2 kPa for the initial 30 seconds, with a frequency of 1 Hz to simulate the slight movement of the buttocks during sitting still; S12. Subsequently, step up the pressure to 10 kPa in 30 seconds and then increase it to 25 kPa until it reaches 40 kPa, with each step of pressure increase lasting 10 seconds to simulate the pressure increase during getting up; S13. Finally, introduce random white noise of 0 - 15 kPa in the last 30 seconds to simulate the disturbance during turning over; S14. Simultaneously start the perfusion of the constant-temperature liquid, inject artificial urine at a rate of 20 ml / min at 37 ± 0.5 °C, and the pressure and liquid injection are strictly synchronized in time sequence, with an error ≤ 50 ms; S15. Real-time collect the injection volume and real-time leakage volume, and calculate the water-locking capacity through integral operation: ; where, is the water-locking capacity, representing the total amount of liquid actually locked by the nursing pad within the pressure cycle; is the injection rate; is the real-time leakage volume; is the total test duration; is the time element (integration variable).

[0030] It should be noted that the composition of the artificial urine contains 9.0 g / L of sodium chloride, 1.8 g / L of urea, and the pH value is 6.8.

[0031] Generally speaking, through the principle of biomechanical mapping, the human activities are decomposed into three types of characteristic pressure waveforms, enabling the specimen to bear the dynamic loads in the real scenario. Compared with the traditional static weights (such as the fixed pressure of 40 kPa in the national standard), the dynamic sequence can stimulate the slow-release water absorption characteristics of the starch-based resin, fully activate the resin swelling in the low-pressure stage, and verify the compressive water-locking ability in the high-pressure stage, thus breaking through the distortion limitation of the short-time test in the national standard and restoring the real usage scenario.

[0032] In some specific embodiments, in the step of S2, the capacitive sensor matrix has a 256-point distributed layout, with a spacing of 5 mm, a sensitivity of 0.1 μl, a data acquisition frequency of 100 ms per time, scans the internal liquid distribution of the specimen, and generates a three-dimensional osmotic thermal map in real time; the hyperspectral imaging frame rate is 60 fps, and the wavelength resolution is 5 nm, captures the expansion and deformation state of the absorbent core, and identifies the boundary of the effective water-locking area.

[0033] Further, the emergency stop is triggered when the capacitive sensor detects that the leakage amount at the edge of the specimen is ≥ 0.3 ml, automatically triggers the emergency stop protection and records the current time , calculate the water-locking efficiency: ; where, is the water-locking efficiency; is the maximum water-locking amount, the cumulative absorption amount before critical leakage; is the effective absorption area, which identifies the actual working area of the core through hyperspectral imaging; is the time to reach the maximum water-locking amount.

[0034] Generally speaking, through the integration of spatial resolution and spectral analysis, it not only solves the blind area problem of traditional single-point leakage detection, but also quantifies the water-locking efficiency into a comparable η value, which not only avoids the industry pain point of misjudgment of starch-based resin due to slow water absorption, but also accurately locates the leakage risk points. Its output η value and spatial penetration map become the core data connecting dynamic testing and grading evaluation, driving the product optimization to shift from empirical guesswork to precise intervention.

[0035] In some specific embodiments, in the step of S3, it specifically includes the following sub-steps: S31. Start after the emergency stop is triggered in the S2 step or the test ends, precisely cut 0.2 g of absorbent core material from the nursing pad specimen, put it into a standard breathable tea bag of 60×85 mm and seal it; S32. Immerse the tea bag completely in 37°C physiological saline (0.9% NaCl) and let it stand for 30 min to ensure that the core is fully saturated; S33. Dehydrate with a centrifuge at a centrifugal force of 250 g for 3 min to remove free liquid; S34. Weigh the total mass of the dehydrated specimen and the tea bag and the mass of the dehydrated blank tea bag of the same batch, and calculate the water retention amount: ; where, is the water retention amount, indicating the mass of the liquid locked by the absorbent core per unit mass; is the dry weight of the specimen, the measured value before the test; is the total mass of the dehydrated specimen + tea bag; is the mass of the dehydrated blank tea bag.

[0036] Generally speaking, based on the material cohesive energy locking mechanism, the critical condition of liquid detachment from the core during human activities is simulated by centrifugal force. During the centrifugal dehydration process, only the free liquid not bound by the polymer network is removed, and the retained liquid mass directly reflects the chemical cross-linking strength of the resin, quantifying the true water locking ability of the starch-based resin after dynamic pressure, thereby revealing the true water retention potential under dynamic pressure.

[0037] In some specific embodiments, in the step of S4, the three-level evaluation system includes: Level I index: absorption speed ≤ 150 s, maximum water locking capacity , water retention ; Level II index: water locking stability under pressure disturbance , backflow index ; Level III index: critical failure pressure ≥ 40 kPa, leakage risk coefficient ; Verify the penetration rate by modifying the Darcy equation.

[0038] Furthermore, the calculation formula for the backflow index is: ; where is the backflow index; is the initial dry weight; is the weight after pressure release; The calculation formula for the leakage risk coefficient is: ; where is the leakage risk coefficient; is the total leakage volume during the whole test process; is the maximum water locking capacity; The modified Darcy equation is: ; where is the liquid penetration speed; is the material permeability, reflecting the pore structure of the core; is the liquid viscosity, and the artificial urine is 0.001 Pa·s (37 °C); is the pressure gradient; is the liquid density, and the artificial urine is 1.05 g / cm 3 ; is the gravitational acceleration (9.8 m / s 2 ); is the material strain correction term, and the calculation formula is: ; where , Determined through calibration tests; is the material compression strain, , is the thickness compression amount, is the initial thickness.

[0039] Specifically, the modified Darcy equation is used to dynamically verify the water-locking stability. In specific implementation, by calculating the pressure gradient in real time and the core material compression strain , inputting into the modified equation to generate the theoretical infiltration rate, comparing it with the measured value of the capacitance sensor in Step S2. If the deviation rate ≤ 5%, it is determined that the material infiltration behavior meets the expectation; if the deviation > 10%, it is marked as the "abnormal expansion area" to participate in the safety risk assessment; The output of the performance report is generated by a machine learning model. Based on a three-level evaluation system, the discrete data of dynamic tests is associated with static water retention indicators and weighted. For example, the starch-based resin has a slow water absorption rate of only 120 ml / 30 s in Step S1, but after the water retention amount R = 22 g / g in Step S3 and η = 85% in Step S2 are jointly weighted, the model automatically compensates for its "slow water absorption and high water-locking" characteristics and outputs Grade A instead of Grade C misjudged by the national standard.

[0040] Furthermore, the algorithm of the machine learning model selects random forest. The input features are the 7-dimensional vectors of the three-level evaluation system, and the output is the three-class probability (Grade A / B / C). The Grad-CAM technology is used to fuse the hyperspectral and capacitance thermograms to generate the spatial coordinates (x, y) of the infiltration weak area; Dataset construction: 800 groups of starch-based resin compliance data (η ≥ 85%, R ≥ 20 g / g) are used as positive samples, 200 groups of traditional resin data (high water absorption but η < 80%) are used as negative samples, and 1000 groups of enhanced samples generated by pressure-liquid parameter perturbation are used for training.

[0041] Example: Taking the starch-acrylamide nursing pad as an example: Output of Step S1: (Compliant), but the absorption amount in 30 seconds is only 150 ml (judged unqualified by the national standard); Output of Step S2: (> 85% threshold), the edge leakage position is 8 cm from the center; Output of Step S3: (Far exceeding the national standard of 20 g / g); Decision in Step S4: The model identifies that the material has "high dynamic water-locking efficiency + strong water retention", ignores the short-term water absorption disadvantage, and comprehensively determines it as Grade A. The infiltration cloud map shows that the leakage point is located at the edge joint (not a defect of the material itself), guiding the production side to optimize the edge sealing process rather than replacing the resin.

[0042] Generally speaking, through the intelligent coupling of dynamic-static indicators and spatial failure location, the "slow water absorption and high water locking" characteristics of starch-based resins are transformed into quantifiable ratings, thereby solving the problem of misjudgment of environmental protection materials in national standards. The graded conclusions and infiltration cloud maps output not only end the extensive judgment of traditional "pass / fail", but also upgrade product optimization from empirical guesswork to precise engineering intervention, forming a closed loop of "detection-diagnosis-improvement".

[0043] As Figures 1-3 shown, a detection device for the water locking performance detection method of a nursing pad includes: a device frame 1, a detection table 2, a fixing frame 3 installed on the top of the device frame 1, and a control system 4 for automatically detecting the water locking performance of the nursing pad by using a controller; a sample slot 21 is opened at the top of the detection table 2, and a clamping mechanism for fixing the nursing pad sample is installed on the detection table 2; a hydraulic cylinder 5 is fixed at the top of the fixing frame 3, a pressing plate 51 is arranged at the bottom of the hydraulic cylinder 5, and a connecting limit mechanism for transmitting the feed amount of the hydraulic cylinder 5 is arranged between the hydraulic cylinder 5 and the pressing plate 51; a plurality of pull rod cylinders 52 are installed on the pressing plate 51, a pressing head 53 is fixed at the output end of the pull rod cylinder 52 at the bottom of the pressing plate 51, and a plurality of hyperspectral cameras 54 are installed on the side of the pressing plate 51; a plurality of capacitance sensors 55 and a plurality of liquid outlet heads 56 are installed at the bottom of the pressing plate 51, a liquid injection flow channel is opened inside the pressing plate 51, and a liquid injection head 57 for externally connecting an infusion device to realize the supply of test solution is fixed on the side of the pressing plate 51.

[0044] It should be noted that a plurality of pull rod cylinders 52, pressing heads 53, capacitance sensors 55, and liquid outlet heads 56 are all evenly distributed in a linear array on the pressing plate 51; the control system 4 is electrically connected to the hyperspectral camera 54, the capacitance sensor 55, the control module of the externally connected infusion device, the hydraulic system of the hydraulic cylinder 5, and the pull rod cylinder 52; the model of the hydraulic cylinder 5 is preferably CJT210; the model of the pull rod cylinder 52 is preferably MOB light-duty cylinder with a cylinder diameter of 50 mm; the model of the hyperspectral camera 54 is preferably LB-FS-2X; the model of the capacitance sensor 55 is preferably LCS-1M30M-F15PNO-K020P.

[0045] Specifically, the specimen groove 21 opened on the test bench 2 is used to place the nursing pad specimen, and the clamping mechanism is used to firmly fix the specimen to prevent displacement during the detection process. The hydraulic cylinder 5 on the fixing frame 3 precisely transmits the pressure to the pressing plate 51 through the connecting limit mechanism, causing the pressing plate 51 to descend to a distance of 10-15 cm from the specimen groove 21. The control system 4 controls the pull rod cylinder 52 on the pressing plate 51 to drive the indenter 53 to apply a composite dynamic pressure sequence including sine wave fluctuations, stepped pressure increases, and random disturbances to the specimen, simulating the complex mechanical environment during actual human use. At the same time, the liquid outlet head 56 at the bottom of the pressing plate 51 injects a constant-temperature liquid into the specimen synchronously through the internal liquid injection flow channel and the external liquid infusion device to achieve liquid perfusion, and uses the capacitance sensor 55 matrix installed at the bottom of the pressing plate 51 to scan the three-dimensional distribution of the liquid in the specimen in real time. Combined with the hyperspectral camera 54, it captures the expansion and deformation state of the nursing pad specimen after absorbing the liquid at a high frame rate and high wavelength resolution, identifies the boundary of the effective water-locking area, and triggers an emergency stop mechanism when edge leakage is detected. Through the data fusion of the capacitance sensor 55 and the hyperspectral camera 54, the control system 4 can accurately calculate key indicators such as the water-locking amount, water-locking efficiency, and water retention amount, and finally output a detailed performance report based on the constructed three-level evaluation system, so as to achieve a comprehensive and accurate detection of the water-locking performance of the nursing pad.

[0046] It can be understood that the hydraulic cylinder 5 and the pull rod cylinder 52 are controlled by an external hydraulic system. The hydraulic system is based on a motor to provide power, uses a hydraulic pump to convert mechanical energy into pressure, pushes the hydraulic oil, and controls various valves to change the flow direction of the hydraulic oil, thereby driving the hydraulic cylinder 5 to perform actions with different strokes and directions. The specific structure is a general standard part or a component known to those skilled in the art. The control method of the control system 4 and the control circuit for realizing the automatic detection of the water-locking performance of the nursing pad are realized through a programmable controller and belong to the prior art. It can be realized by programming by those skilled in the art and belongs to the common knowledge in the art. Therefore, the control method and module of the present application will not be explained in detail here and will not be elaborated in detail.

[0047] As Figure 4 shown, in some specific embodiments, the clamping mechanism includes: a plurality of threaded holes 6 opened at the top of the test bench 2, adjusting bolts 61 threadedly connected inside the threaded holes 6, and connecting blocks 62 rotatably connected to the sides of the adjusting bolts 61; a pressing piece 63 is fixed to the bottom of the connecting block 62.

[0048] It should be noted that the number of the threaded holes 6, the adjusting bolts 61, the connecting blocks 62, and the pressing pieces 63 is the same, and the bottom of the pressing piece 63 is located inside the specimen groove 21.

[0049] Specifically, after the nursing pad specimen is placed flat inside the specimen slot 21, rotate the adjusting bolt 61 to screw it into the threaded hole 6. Since the connecting block 62 is rotatably connected to the adjusting bolt 61, during the screwing process, manually limit the connecting block 62 to make the pressing piece 63 located inside the specimen slot 21, and then the pressing piece 63 can be pressed down to the top of the nursing pad specimen inside the specimen slot 21, so that nursing pad specimens with different thicknesses are kept flat and wrinkle-free inside the specimen slot 21, thereby utilizing the self-locking property of the thread to achieve adjustable fixing force and avoiding misjudgment of leakage caused by specimen displacement during the test.

[0050] As Figure 2 shown, in some specific embodiments, the connection and limit mechanism includes: a plurality of connecting rods 7 fixed to the top of the pressing plate 51, and a connecting frame 71 fixed between the plurality of connecting rods 7; the top of the connecting frame 71 is fixed to the output end of the hydraulic cylinder 5, and the sides of the plurality of connecting rods 7 are sleeved inside the fixing frame 3.

[0051] It should be noted that the plurality of connecting rods 7 are arranged in parallel with the hydraulic cylinder 5 and perpendicular to the pressing plate 51.

[0052] Specifically, during the feeding process of the hydraulic cylinder 5, its output end can be transmitted to the plurality of connecting rods 7 by the connecting frame 71. Since the bottom ends of the plurality of connecting rods 7 are fixed to the pressing plate 51, it can drive the pressing plate 51 to move synchronously to achieve lifting. At the same time, since the sides of the connecting rods 7 are sleeved inside the fixing frame 3, it can ensure that the lifting transmission path is perpendicular to the plane of the pressing plate 51, thereby improving the stability and reliability of the lifting movement.

[0053] Based on the ideal embodiments of the present invention as an inspiration, through the above description, for those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention. Any reference signs in the claims should not be regarded as limiting the claimed rights.

[0054] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for detecting the water locking performance of a nursing pad, which is applicable to detecting the water locking performance of a nursing pad with a water-absorbing resin of a starch-grafted copolymer with acrylic acid or acrylamide monomer as the absorbent core material, is characterized in that, It includes the following steps: S1. Fix the nursing pad specimen on the detection platform, apply a composite dynamic pressure sequence including sine wave fluctuations, stepped pressure boosting, and random perturbations, inject a constant-temperature liquid into the specimen synchronously, and calculate the water locking capacity; S2. Real-time scan the three-dimensional liquid distribution through a capacitance sensor matrix, capture the swelling state of the core by combining hyperspectral imaging, trigger an emergency stop when edge leakage is detected, and calculate the water locking efficiency; S3. Take the absorbent core material, soak it in physiological saline for 30 minutes, and then centrifuge and dehydrate it to calculate the water retention capacity; S4. Based on the water locking capacity, water locking efficiency, water retention capacity, and rewetting index, construct a three-level evaluation system to output a performance report.

2. The water locking performance detection method of a nursing pad according to claim 1, wherein: In the step of S1, the dynamic pressure sequence includes: t = 0 - 30s: Sine wave pressure 5 ± 2 kPa, frequency 1 Hz; t = 30 - 60s: Stepwise pressure increase from 10 kPa to 25 kPa to 40 kPa, with each step of pressure increase for 10 s; t = 60 - 90s: White noise random pressure 0 - 15 kPa.

3. A method for detecting the water locking performance of a nursing pad according to claim 1, characterized in that: In the step of S1, the calculation formula for the water locking capacity is: ； Among them, is the water locking capacity; is the injection rate; is the real-time leakage volume; is the total test duration; is the time element.

4. A water lock performance detection method for a nursing pad according to claim 1, characterized in that: In the step of S2, the capacitance sensor matrix is a 256-point distributed layout, with a spacing of 5 mm, a sensitivity of 0.1 μl, and a data acquisition frequency of 100 ms / time; the hyperspectral imaging frame rate is 60 fps, and the wavelength resolution is 5 nm; the calculation formula for the water locking efficiency is: ； Among them, is the water locking efficiency; is the maximum water locking capacity; is the effective absorption area; is the time to reach the maximum water locking capacity.

5. A water locking performance detection method for a nursing pad according to claim 1, characterized in that: In the step of S3, the centrifugation condition is dehydration at a centrifugal force of 250 g for 3 minutes; the calculation formula for the water retention capacity is: ； Among them, is the water retention capacity; is the dry weight of the specimen; is the total mass of the specimen + tea bag after dehydration; is the mass of the blank tea bag after dehydration.

6. A method for detecting the water locking performance of a nursing pad according to claim 1, characterized in that: In the step of S4, the three-level evaluation system includes: Level I indicators: Absorption speed, maximum water locking capacity, water retention capacity; Level II indicators: Water locking stability under pressure perturbation, rewetting index; Level III indicators: Critical failure pressure, leakage risk coefficient; Verify the permeation rate by modifying the Darcy equation.

7. A method for detecting the water-locking performance of a nursing pad according to claim 6, characterized in that: The calculation formula for the rewetting index is: ； Among them, is the backflow index; is the initial dry weight; is the weight after pressure release; The calculation formula for the leakage risk coefficient is: ； Among them, is the leakage risk coefficient; is the total leakage volume during the whole testing process; is the maximum water locking volume; The modified Darcy equation is: ； Among them, is the liquid penetration speed; is the material permeability; is the liquid viscosity; is the pressure gradient; is the liquid density; is the acceleration due to gravity; is the material strain correction term, and the calculation formula is: ; among them, , ; is the material compressive strain, , is the thickness compression amount, is the initial thickness.

8. A detection device for the water-locking performance detection method of a nursing pad according to any one of claims 1-7, characterized in that, It includes: An equipment frame, a detection table, a fixing frame installed on the top of the equipment frame, and a control system for automatically detecting the water locking performance of the nursing pad by using a controller; A specimen groove is opened at the top of the detection table, and a clamping mechanism for fixing the nursing pad specimen is installed on the detection table; a hydraulic cylinder is fixed on the top of the fixing frame, a pressing plate is arranged at the bottom of the hydraulic cylinder, and a connection limiting mechanism for transmitting the feed amount of the hydraulic cylinder is arranged between the hydraulic cylinder and the pressing plate; A plurality of pull rod cylinders are installed on the pressing plate, a pressing head is fixed at the output end of the pull rod cylinder located at the bottom of the pressing plate, and a plurality of hyperspectral cameras are installed on the side of the pressing plate; A plurality of capacitance sensors and a plurality of liquid outlets are installed at the bottom of the pressing plate, a liquid injection flow channel is opened inside the pressing plate, and a liquid injection head for externally connecting an infusion device to realize the supply of the test solution is fixed on the side of the pressing plate; 9. The detection device for the water locking performance detection method of a nursing pad according to claim 8, wherein: The clamping mechanism includes: a plurality of threaded holes opened at the top of the detection table, adjusting bolts threadedly connected inside the threaded holes, and connection blocks rotatably connected to the sides of the adjusting bolts; a pressing piece is fixed at the bottom of the connection block.

10. The detection device for the water locking performance detection method of a nursing pad according to claim 8, characterized in that: The connection and limit mechanism includes: a plurality of connecting rods fixed to the top of the pressing plate, and a connection frame fixed between the plurality of connecting rods; the top of the connection frame is fixed to the output end of the hydraulic cylinder, and the sides of the plurality of connecting rods are sleeved with the inner side of the fixed frame.

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