A device and method for testing the water-locking performance of a nursing pad

Abstract

The present invention discloses a device and method for testing the water-locking performance of a nursing pad, which relates to the field of material performance testing. The testing method comprises the following steps: S1, fixing a nursing pad sample on a testing platform, applying a composite dynamic pressure sequence comprising sinusoidal fluctuations, step-by-step pressurization, and random perturbations, and simultaneously injecting a constant-temperature liquid into the sample to calculate the water-locking capacity; S2, scanning the three-dimensional distribution of the liquid in real time to capture the core expansion state, triggering an emergency stop when the edge leaks, and calculating the water-locking efficiency; S3, taking the absorbent core material, soaking it in physiological saline, and then centrifuging and dehydrating it to calculate the water retention capacity; S4, constructing a three-level evaluation system to output a performance report. The present invention uses composite multi-point pressure to simulate the mechanical characteristics of human activity, and combines multimodal sensing technology to track the three-dimensional liquid penetration process in real time. This overcomes the defects of traditional methods, such as the single pressure and insufficient detection dimensions, and provides dynamic process analysis support for product optimization that cannot be achieved by traditional static testing.

Description

Technical Field

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

[0002] In modern society, with the intensification of an aging population and a growing emphasis on personal hygiene, nursing pads, as a crucial hygiene product, are experiencing a growing market demand. A typical nursing pad structure consists of a skin-friendly nonwoven fabric surface layer, a PE film with a high barrier performance as a backing layer, and an absorbent core made of a high-molecular-weight, water-absorbing resin sandwiched between the two. Their primary function is to rapidly absorb and retain fluids like urine and blood, keeping the user's skin dry and preventing skin problems like diaper rash. Therefore, the water-retention capacity of nursing pads has become a key quality indicator.

[0003] Traditional testing instruments currently use static weight application to test the moisture retention of nursing pads. This method simulates pressure by applying a fixed weight to the sample surface. However, the pressure generated by the human body during actual use is dynamic (for example, movements such as turning over and sitting up cause fluctuations in pressure amplitude and frequency), and static pressure application cannot replicate this complex mechanical environment.

[0004] Therefore, traditional testing methods have obvious shortcomings in evaluating the water-locking performance of nursing pads, and a more scientific and accurate testing method is urgently needed. Summary of the Invention

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

[0006] To achieve the above-mentioned object, the technical solution adopted by the present invention is: a method for testing the water-locking performance of a nursing pad, which is applicable to the water-locking performance testing of a nursing pad whose absorbent core material is a water-absorbing resin composed of a graft copolymer of starch and acrylic acid or acrylamide monomers, comprising the following steps:

[0007] S1. Fix the nursing pad sample on the testing platform and apply a composite dynamic pressure sequence including sinusoidal fluctuations, step pressure increase, and random disturbance. Simultaneously, inject a constant temperature liquid into the sample and calculate the water lock capacity.

[0008] S2 uses a capacitive sensor matrix to scan the three-dimensional distribution of liquid in real time, combined with hyperspectral imaging to capture the core expansion state. When edge leakage is detected, an emergency stop is triggered and the water locking efficiency is calculated;

[0009] S3. Take the absorbent core material, soak it in physiological saline for 30 minutes, then centrifuge and dehydrate it, and calculate the water retention;

[0010] S4. Based on water lock capacity, water lock efficiency, water retention capacity and re-infiltration index, a three-level evaluation system is constructed to output performance reports.

[0011] In a preferred embodiment of the present invention, in step S1, the dynamic pressure sequence includes:

[0012] t=0-30s: sine wave pressure 5±2kPa, frequency 1Hz;

[0013] t=30-60s: step-by-step pressurization from 10kPa to 25kPa to 40kPa, with each step lasting 10s;

[0014] t=60-90s: White noise random pressure 0-15kPa.

[0015] In a preferred embodiment of the present invention, in step S1, the calculation formula for the water lock amount is:

[0016] ;

[0017] in, It is the amount of water locked; is the injection rate; is the real-time leakage amount; is the total test duration; It is the time element.

[0018] In a preferred embodiment of the present invention, in step S2, the capacitive sensor matrix has a 256-point distributed layout, 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 lock efficiency is:

[0019] ;

[0020] in, It is the water locking efficiency; is the maximum water lock capacity; is the effective absorption area; This is the time to reach the maximum water lock amount.

[0021] In a preferred embodiment of the present invention, in step S3, the centrifugal condition is 250g centrifugal force dehydration for 3 minutes; the calculation formula of the water retention capacity is:

[0022] ;

[0023] in, is the water retention capacity; is the dry weight of the specimen; is the total mass of the dehydrated sample + tea bag; It is the mass of a blank tea bag after dehydration.

[0024] In a preferred embodiment of the present invention, in step S4, the three-level evaluation system includes:

[0025] Level I indicators: absorption speed, maximum water lock capacity, water retention capacity;

[0026] Level II indicators: water lock stability and re-seepage index under pressure disturbance;

[0027] Level III indicators: critical failure pressure, leakage risk coefficient;

[0028] The permeation rate was verified by the modified Darcy equation.

[0029] In a preferred embodiment of the present invention, the calculation formula of the re-infiltration index is:

[0030] ;

[0031] in, is the refiltration index; is the initial dry weight; is the weight after pressure is released;

[0032] The calculation formula of the leakage risk coefficient is:

[0033] ;

[0034] in, is the leakage risk factor; It is the total leakage during the whole test process; is the maximum water lock capacity;

[0035] The modified Darcy equation is:

[0036] ;

[0037] in, is the liquid penetration rate; is the material permeability; is the liquid viscosity; is the pressure gradient; is the density of the liquid; is the acceleration due to gravity; is the material strain correction term, and its calculation formula is: ;in, , ; is the material compressive strain, , is the thickness compression, is the initial thickness.

[0038] The present invention provides a testing device for a method for testing the water-locking performance of a nursing pad, comprising: an equipment rack, a testing platform installed on the top of the equipment rack, a fixing rack, and a control system for automatically testing the water-locking performance of the nursing pad using a controller;

[0039] A sample slot is provided on the top of the testing platform, and a clamping mechanism for fixing the nursing pad sample is installed on the testing platform; a hydraulic cylinder is fixed on the top of the fixing frame, a pressing plate is provided at the bottom of the hydraulic cylinder, and a connection limit mechanism for transmitting the feed amount of the hydraulic cylinder is provided between the hydraulic cylinder and the pressing plate;

[0040] A plurality of tie rod cylinders are installed on the pressing plate, a pressure head is fixed on the output end of the tie 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;

[0041] A plurality of capacitance sensors and a plurality of liquid outlet heads are installed at the bottom of the pressing plate, a liquid injection channel is opened inside the pressing plate, and an infusion head for connecting an external infusion device to supply the test solution is fixed on the side of the pressing plate.

[0042] In a preferred embodiment of the present invention, the clamping mechanism includes: a plurality of threaded holes opened on the top of the detection platform, an adjusting bolt threadedly connected to the inner side of the threaded hole, and a connecting block rotatably connected to the side of the adjusting bolt; a pressing plate is fixed to the bottom of the connecting block.

[0043] In a preferred embodiment of the present invention, the connection limiting mechanism includes: a plurality of connecting rods fixed on the top of the pressure plate, and a connecting frame fixed between the plurality of connecting rods; the top of the connecting frame is fixed to the output end of the hydraulic cylinder, and the side surfaces of the plurality of connecting rods are socketed with the inner side of the fixing frame.

[0044] The present invention solves the defects existing in the background technology and has the following beneficial effects:

[0045] (1) The present invention provides a device and method for testing the water-locking performance of a nursing pad. By coordinating the dynamic pressure loading and liquid perfusion, the authenticity and accuracy of the water-locking performance testing of the nursing pad are significantly improved. Composite multi-point pressure is used to simulate the mechanical characteristics of human activities. Multimodal sensing technology is combined to track the three-dimensional penetration process of liquid in real time, overcoming the defects of the traditional method of single pressure and insufficient detection dimension. An intelligent algorithm is used to integrate multiple parameters such as leakage risk coefficient and back-seepage amount to construct a comprehensive evaluation system, which improves the detection accuracy to micro-level upgrades. At the same time, a visual penetration cloud map and material failure warning data are generated, providing dynamic process analysis support for product optimization that cannot be achieved by traditional static detection.

[0046] (2) In the present invention, a new evaluation system with water-locking efficiency as the core simulates human activities through dynamic pressure sequences, combines liquid perfusion with multimodal sensing technology, and tracks the penetration behavior of materials under real pressure in real time. The single indicator of short-term absorption amount is then expanded into a dynamic model of water-locking efficiency, which quantifies the water-locking capacity per unit time and per unit area. This fundamentally solves the problem of performance misjudgment of starch-based resins due to slow water absorption, and provides technical support for the accurate evaluation of environmentally friendly materials.

[0047] (3) In the present invention, a three-level indicator system including basic performance, dynamic performance and safety performance is constructed, and a strain correction term is introduced into the traditional Darcy equation to quantify the effect of core pore blockage on the penetration rate under compressive strain of the material. When the material is compressed to a critical deformation, the system automatically triggers a failure warning, which can facilitate the guidance of product optimization of the design of the compressive structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments described in the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive efforts.

[0049] Figure 1 This is a three-dimensional structural diagram of a nursing pad water-locking performance testing device according to a preferred embodiment of the present invention;

[0050] Figure 2 This is a schematic diagram of the distribution of several tie rod cylinders in a preferred embodiment of the present invention;

[0051] Figure 3 Schematic diagram of several pressure head distributions and partial enlarged diagrams of the preferred embodiment of the present invention;

[0052] Figure 4 This is a structural diagram of the separation of the adjusting bolt and the threaded hole in a preferred embodiment of the present invention;

[0053] In the figure: 1. Equipment frame; 2. Test table; 21. Sample slot; 3. Fixing frame; 4. Control system; 5. Hydraulic cylinder; 51. Pressing plate; 52. Tie rod cylinder; 53. Pressing head; 54. Hyperspectral camera; 55. Capacitive sensor; 56. Liquid outlet head; 57. Infusion head; 6. Threaded hole; 61. Adjusting bolt; 62. Connecting block; 63. Pressing piece; 7. Connecting rod; 71. Connecting frame. DETAILED DESCRIPTION

[0054] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0055] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0056] In the description of this application, it should be understood that the terms "top," "bottom," "inside," "outside," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate the description of this application and simplify the description. They do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this application. In the description of the present invention, unless otherwise specified, "several" means two or more.

[0057] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "installed," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0058] Application Overview:

[0059] After an in-depth analysis of the actual usage scenarios of nursing pads, the applicant found that the national standard testing method is seriously insufficiently adaptable to new environmentally friendly materials.

[0060] Specifically, starch-based resin, which is a graft copolymer of starch and monomers such as acrylic acid and acrylamide (such as starch-acrylic acid graft resin), is an environmentally friendly material with moderate water absorption due to its unique chemical structure. It is particularly suitable for mild electrolyte solution environments, such as nursing pads designed for people with allergies or environmental protection needs.

[0061] The applicant discovered that under the testing framework of the current national standard GB / T 22875-2018 "Superabsorbent Resins for Diapers and Sanitary Napkins," the testing logic for absorbent core materials—polyacrylate resins—relies on short-term absorption performance testing. However, when simulating the actual use environment of nursing pads, starch-based resins exhibit significant water absorption hysteresis due to their molecular structure characteristics. Their 30-second absorption capacity is significantly lower than that of polyacrylic acid resins, but their saturated water retention capacity is close to the latter's level. Furthermore, they are unable to reach saturation within the short time specified by the national standard, resulting in a low measured absorption rate that cannot truly reflect their water retention performance in actual use. This shows that the traditional "absorption rate" indicator cannot objectively evaluate the performance advantages of starch-based resins, but instead misleads product design.

[0062] In response to the above problems, the applicant proposed a device and method for testing the water-locking performance of nursing pads. This new evaluation system, with water-locking efficiency as the core, simulates human activities through dynamic pressure sequences, combines liquid perfusion with multimodal sensing technology, and tracks the penetration behavior of materials under real pressure in real time. The single indicator of short-term absorption amount is then expanded into a dynamic model of water-locking efficiency, quantifying the water-locking capacity per unit time and per unit area, fundamentally solving the problem of performance misjudgment caused by slow water absorption of starch-based resins, and providing technical support for the accurate evaluation of environmentally friendly materials.

[0063] A method for testing the water-locking performance of a nursing pad is applicable to testing the water-locking performance of a nursing pad using a water-absorbing resin comprising a graft copolymer of starch and acrylic acid or acrylamide monomers as an absorbent core material, comprising the following steps:

[0064] S1. Fix the nursing pad sample on the testing platform and apply a composite dynamic pressure sequence including sinusoidal fluctuations, step pressure increase, and random disturbance. Simultaneously, inject a constant temperature liquid into the sample and calculate the water lock capacity.

[0065] S2 uses a capacitive sensor matrix to scan the three-dimensional distribution of liquid in real time, combined with hyperspectral imaging to capture the core expansion state. When edge leakage is detected, an emergency stop is triggered and the water locking efficiency is calculated;

[0066] S3. Take the absorbent core material, soak it in physiological saline for 30 minutes, then centrifuge and dehydrate it, and calculate the water retention;

[0067] S4. Based on water lock capacity, water lock efficiency, water retention capacity and re-infiltration index, a three-level evaluation system is constructed to output performance reports.

[0068] In some specific embodiments, the step S1 includes the following sub-steps:

[0069] S11: Apply a sinusoidal pressure of 5±2 kPa for the first 30 seconds at a frequency of 1 Hz to simulate micro-movements of the buttocks during sitting;

[0070] S12: Subsequently, the pressure is increased stepwise to 10 kPa, then to 25 kPa, and finally to 40 kPa over 30 seconds, with each step increasing for 10 seconds to simulate standing up and applying pressure.

[0071] S13, in the last 30 seconds, 0-15 kPa random white noise was introduced to simulate the turning disturbance;

[0072] S14. Synchronously start constant temperature liquid perfusion, injecting 37±0.5℃ artificial urine at a rate of 20ml / min. The pressure and liquid injection are strictly synchronized with the timing, with an error of ≤50ms;

[0073] S15. Real-time collection of injection volume and leakage volume, and calculation of water lock volume by integral operation:

[0074] ;

[0075] in, It is the water lock amount, which indicates the total amount of liquid actually locked by the nursing pad during the pressure cycle; is the injection rate; is the real-time leakage amount; is the total test duration; is the time differential (integral variable).

[0076] It should be noted that the composition of artificial urine includes 9.0g / L of sodium chloride and 1.8g / L of urea, and the pH value is 6.8.

[0077] In general, through the principle of biomechanical mapping, human activities are decomposed into three types of characteristic pressure waveforms, allowing the specimens to withstand dynamic loads in real scenarios. Compared with traditional static weights (such as the national standard 40kPa fixed pressure), the dynamic sequence can stimulate the slow-release water absorption properties of starch-based resins, fully initiate resin swelling in the low-pressure stage, and verify the pressure resistance and water-locking ability in the high-pressure stage, thereby breaking through the distortion limitations of the national standard short-time test and restoring the real usage scenario.

[0078] In some specific embodiments, in step S2, the capacitive sensor matrix has a 256-point distributed layout, a spacing of 5mm, a sensitivity of 0.1μl, a data acquisition frequency of 100ms / time, scans the liquid distribution inside the sample, and generates a three-dimensional penetration thermogram in real time; the hyperspectral imaging frame rate is 60fps, the wavelength resolution is 5nm, captures the expansion and deformation state of the absorption core, and identifies the boundary of the effective water-locking area.

[0079] Furthermore, the emergency stop trigger is when the capacitance sensor detects that the leakage at the edge of the sample is ≥0.3ml, it automatically triggers the emergency stop protection and records the current time , calculate the water locking efficiency:

[0080] ;

[0081] in, It is the water locking efficiency; is the maximum water lock capacity, the cumulative absorption before critical leakage; It is the effective absorption area, which is used to identify the actual active area of ​​the core through hyperspectral imaging; This is the time to reach the maximum water lock amount.

[0082] In general, the integration of spatial resolution and spectral analysis not only solves the blind spot problem of traditional single-point leakage detection, but also quantifies the water-locking efficiency into a comparable η value. This not only avoids the industry pain point of starch-based resins being misjudged due to slow water absorption, but also accurately locates leakage risk points. The output η value and spatial penetration map become the core data connecting dynamic testing and graded evaluation, driving product optimization from empirical speculation to precise intervention.

[0083] In some specific implementations, the step S3 specifically includes the following sub-steps:

[0084] S31. When the emergency stop is triggered in step S2 or the test is completed, accurately cut 0.2g of absorbent core material from the nursing pad sample, put it into a 60×85mm standard breathable tea bag and seal it;

[0085] S32. Immerse the tea bag completely in 37°C saline (0.9% NaCl) and let it sit for 30 minutes to ensure that the core is fully saturated.

[0086] S33, dehydrate using a centrifuge at 250g for 3 minutes to remove free liquid;

[0087] S34. Weigh the total mass of the dehydrated sample and tea bag, and the dehydrated mass of the blank tea bag from the same batch, and calculate the water retention:

[0088] ;

[0089] in, It is the water retention capacity, which indicates the mass of liquid locked by the unit mass of the absorbent core; is the dry weight of the specimen, weighed before testing; is the total mass of the dehydrated sample + tea bag; It is the mass of a blank tea bag after dehydration.

[0090] In general, based on the material's cohesive energy locking mechanism, centrifugal force is used to simulate the critical conditions for liquid to separate from the core during human activity. The centrifugal dehydration process only removes the free liquid that is not bound by the polymer network. 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.

[0091] In some specific embodiments, in step S4, the three-level evaluation system includes:

[0092] Level Ⅰ indicators: absorption speed ≤ 150s, maximum water lock capacity , water retention capacity ;

[0093] Level II indicator: water lock stability under pressure disturbance , re-infiltration index ;

[0094] Level III indicators: critical failure pressure ≥ 40kPa, leakage risk coefficient ;

[0095] The permeation rate was verified by the modified Darcy equation.

[0096] Furthermore, the calculation formula of the re-infiltration index is:

[0097] ;

[0098] in, is the refiltration index; is the initial dry weight; is the weight after pressure is released;

[0099] The calculation formula for leakage risk coefficient is:

[0100] ;

[0101] in, is the leakage risk factor; It is the total leakage during the whole test process; is the maximum water lock capacity;

[0102] The modified Darcy equation is:

[0103] ;

[0104] in, is the liquid penetration rate; is the material permeability, reflecting the core pore structure; is the viscosity of the liquid, which is 0.001 Pa·s for artificial urine (37°C); is the pressure gradient; is the density of the liquid, artificial urine is 1.05 g / cm 3 ; is the acceleration due to gravity (9.8 m / s 2 ); is the material strain correction term, and its calculation formula is: ;in, , Determined by calibration test; is the material compressive strain, , is the thickness compression, is the initial thickness.

[0105] Specifically, the modified Darcy equation is used to dynamically verify the water lock stability. In the specific implementation, the pressure gradient is calculated in real time. Compressive strain of the core material , input the correction equation to generate the theoretical permeation rate, and compare it with the actual value measured by the capacitance sensor in step S2. If the deviation rate is ≤5%, it is determined that the material permeation behavior is in line with expectations; if the deviation is greater than 10%, it is marked as an "abnormal expansion area" for safety risk assessment;

[0106] The performance report is output using a machine learning model. Based on a three-level evaluation system, the discrete data of dynamic tests are associated with static water retention indicators and assigned weights. For example, the starch-based resin absorbs water slowly in step S1, resulting in an absorption rate of only 120ml / 30s. However, after weighting the water retention capacity R=22g / g in step S3 and η=85% in step S2, the model automatically compensates for its "slow water absorption and high water lock" characteristics and outputs grade A instead of the C grade mistakenly judged by the national standard.

[0107] Furthermore, the algorithm of the machine learning model selects random forest, the input feature is a 7-dimensional vector of the three-level evaluation system, the output is a three-class probability (A / B / C grade), and the Grad-CAM technology is used to fuse the hyperspectral spectrum and the capacitance thermodynamic map to generate the spatial coordinates (x, y) of the weak penetration area; data set construction: 800 groups of starch-based resin qualified 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.

[0108] Example:

[0109] Take starch-acrylamide nursing pads as an example:

[0110] Output of step S1: (meets the standard), but the absorption volume in 30 seconds is only 150ml (determined to be unqualified by the national standard);

[0111] Output of step S2: (>85% threshold), the edge leakage position was 8 cm from the center;

[0112] S3 step output: (far exceeding the national standard of 20g / g);

[0113] Decision-making in step S4: The model identifies the material as having "high dynamic water-locking efficiency and strong water retention," ignoring any short-term water absorption disadvantages and assigning it an A rating. The permeability cloud map indicates that the leak is located at the edge seam (not a material defect), guiding the production side to optimize the edge sealing process rather than replacing the resin.

[0114] In summary, through the intelligent coupling of dynamic and static indicators and spatial failure localization, the "slow water absorption and high water retention" characteristics of starch-based resins are transformed into quantifiable ratings, thereby resolving the issue of misjudgment of environmentally friendly materials by national standards. The resulting grading conclusions and permeation cloud maps not only eliminate the traditional "pass / fail" approach to crude judgment, but also elevate product optimization from empirical speculation to precise engineering intervention, forming a closed loop of "testing-diagnosis-improvement."

[0115] like Figure 1-3 As shown, a testing device for a method for testing the water-locking performance of a nursing pad comprises: an equipment frame 1, a testing platform 2 installed on the top of the equipment frame 1, a fixing frame 3, and a control system 4 for automatically testing the water-locking performance of a nursing pad using a controller; a sample slot 21 is provided on the top of the testing platform 2, and a clamping mechanism for fixing the nursing pad sample is installed on the testing platform 2; a hydraulic cylinder 5 is fixed on the top of the fixing frame 3, a pressing plate 51 is provided at the bottom of the hydraulic cylinder 5, and a connecting limit mechanism for transmitting the feed amount of the hydraulic cylinder 5 is provided between the hydraulic cylinder 5 and the pressing plate 51; a plurality of pull rod cylinders 52 are installed on the pressing plate 51, and a pressure head 53 is fixed at the output end of the pull rod cylinder 52 located 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 capacitive sensors 55 and a plurality of liquid outlet heads 56 are installed at the bottom of the pressing plate 51, an injection channel is provided inside the pressing plate 51, and an infusion head 57 for connecting an external infusion device to realize the supply of test solution is fixed on the side of the pressing plate 51.

[0116] It should be noted that several tie rod cylinders 52, pressure heads 53, capacitive sensors 55 and liquid outlet heads 56 are evenly distributed in a linear array on the pressure plate 51; the control system 4 is electrically connected to the hyperspectral camera 54, the capacitive sensor 55, the control module of the external infusion device, the hydraulic cylinder 5 and the hydraulic system of the tie rod cylinder 52; the model of the hydraulic cylinder 5 is preferably CJT210; the model of the tie rod cylinder 52 is preferably MOB light cylinder with a cylinder diameter of 50 mm; the model of the hyperspectral camera 54 is preferably LB-FS-2X; the model of the capacitive sensor 55 is preferably LCS-1M30M-F15PNO-K020P.

[0117] Specifically, the sample slot 21 opened on the test table 2 is used to place the nursing pad sample, and the clamping mechanism is used to firmly fix the sample to prevent displacement during the test. The hydraulic cylinder 5 on the fixed frame 3 accurately transmits the pressure to the pressing plate 51 through the connection limit mechanism, so that the pressing plate 51 is lowered to a distance of 10-15 cm from the sample slot 21. The control system 4 controls the pull rod cylinder 52 on the pressing plate 51 to drive the pressure head 53 to apply a composite dynamic pressure sequence containing sinusoidal fluctuations, step-by-step pressurization and random disturbances to the sample to simulate the complex mechanical environment of the human body during actual use. At the same time, the liquid outlet 56 at the bottom of the pressing plate 51 is connected to the internal injection channel and the external infusion equipment to constantly Warm liquid is injected into the sample synchronously to achieve liquid perfusion, and the capacitance sensor 55 matrix installed at the bottom of the pressure plate 51 is used to scan the three-dimensional distribution of the liquid in the sample in real time. Combined with the hyperspectral camera 54, the expansion deformation state of the nursing pad sample after absorbing the liquid is captured at a high frame rate and high wavelength resolution, and the boundary of the effective water-locking area is identified. When edge leakage is detected, the emergency stop mechanism is triggered. 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 water locking amount, water locking efficiency and water retention, and finally output a detailed performance report based on the constructed three-level evaluation system, thereby realizing comprehensive and accurate detection of the water-locking performance of the nursing pad.

[0118] It can be understood that the hydraulic cylinder 5 and the tie rod cylinder 52 are controlled by an external hydraulic system. The hydraulic system is powered by an electric motor and uses a hydraulic pump to convert mechanical energy into pressure to push the hydraulic oil and control various valves to change the flow direction of the hydraulic oil, thereby pushing the hydraulic cylinder 5 to perform actions of different strokes and directions. The specific structure is a general standard part or a component known to those skilled in the art, as well as a control method of the control system 4 and a control circuit for automatically detecting the water-locking performance of the nursing pad. It is implemented by a programmable controller and belongs to the prior art. It can be implemented by programming by those skilled in the art and is common knowledge in the art. Therefore, this application no longer explains the control method and module in detail, and no detailed description is made here.

[0119] like Figure 4 As shown, in some specific embodiments, the clamping mechanism includes: a plurality of threaded holes 6 opened on the top of the detection platform 2, an adjusting bolt 61 threadedly connected to the inner side of the threaded hole 6, and a connecting block 62 rotatably connected to the side of the adjusting bolt 61; a pressing plate 63 is fixed to the bottom of the connecting block 62.

[0120] It should be noted that the numbers of the threaded holes 6 , the adjusting bolts 61 , the connecting blocks 62 and the pressing pieces 63 are the same, and the bottom of the pressing piece 63 is located inside the sample tank 21 .

[0121] Specifically, after the nursing pad sample is placed flatly inside the sample slot 21, the adjusting bolt 61 is rotated to screw it into the threaded hole 6. Since the connecting block 62 is rotatably connected to the adjusting bolt 61, during the screwing-in process, the connecting block 62 is manually limited so that the pressing piece 63 is located inside the sample slot 21, and then the pressing piece 63 can be pressed down inside the sample slot 21 to the top of the nursing pad sample, so that nursing pad samples of different thicknesses remain flat and wrinkle-free in the sample slot 21, thereby utilizing the self-locking characteristics of the thread to achieve adjustable fixing force, thereby avoiding misjudgment of leakage caused by sample displacement during testing.

[0122] like Figure 2 As shown, in some specific embodiments, the connection limiting mechanism includes: a plurality of connecting rods 7 fixed on the top of the pressure 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 side surfaces of the plurality of connecting rods 7 are socketed with the inner side of the fixing frame 3.

[0123] It should be noted that the connecting rods 7 are arranged parallel to the hydraulic cylinder 5 and perpendicular to the pressing plate 51 .

[0124] Specifically, during the feeding process of the hydraulic cylinder 5, its output end can be transmitted to several connecting rods 7 by the connecting frame 71. Since the bottom ends of several connecting rods 7 are fixed to the pressure plate 51, the pressure plate 51 can be driven to move synchronously to achieve lifting. At the same time, since the side of the connecting rod 7 is socketed with the inner side of the fixed frame 3, it can ensure that the lifting transmission path is perpendicular to the plane of the pressure plate 51, thereby improving the stability and reliability of the lifting movement.

[0125] The above description is based on the ideal embodiment of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, the embodiments should be considered as illustrative and non-restrictive in all respects. The scope of the present invention is defined by the appended claims, not the foregoing description, and it is intended that all variations within the meaning and range of equivalents of the claims be encompassed within the present invention. Any reference signs in the claims should not be construed as limiting the claim to which they relate.

[0126] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A method for testing the water-locking performance of a nursing pad, suitable for testing the water-locking performance of a nursing pad using a water-absorbing resin grafted copolymer of starch and acrylic acid or acrylamide monomer as the absorbent core material, characterized in that: The following steps are involved: S1. Fix the nursing pad sample on the testing platform and apply a composite dynamic pressure sequence including sinusoidal fluctuations, step pressure increase, and random disturbance. Simultaneously, inject a constant temperature liquid into the sample and calculate the water lock capacity. S2 uses a capacitive sensor matrix to scan the three-dimensional distribution of liquid in real time, combined with hyperspectral imaging to capture the core expansion state. When edge leakage is detected, an emergency stop is triggered and the water locking efficiency is calculated; S3. Take the absorbent core material, soak it in normal saline for 30 minutes, then centrifuge and dehydrate it, and calculate the water retention; S4. Based on water lock capacity, water lock efficiency, water retention capacity and re-infiltration index, a three-level evaluation system is constructed to output performance reports.

2. A method for detecting the water-locking performance of a nursing pad according to claim 1, characterized in that: In step S1, the dynamic pressure sequence includes: t=0-30s: sine wave pressure 5±2kPa, frequency 1Hz; t=30-60s: step-by-step pressurization from 10kPa to 25kPa to 40kPa, with each step lasting 10s; t=60-90s: White noise random pressure 0-15kPa.

3. A method for testing the water-locking performance of a nursing pad according to claim 1, characterized in that: In step S1, the calculation formula for the water lock amount is: ； in, It is the amount of water locked; is the injection rate; is the real-time leakage amount; is the total test duration; It is the time element.

4. A method for testing the water-locking performance of a nursing pad according to claim 1, characterized in that: In step S2, the capacitive sensor matrix has a 256-point distributed layout, 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: ； in, It is the water locking efficiency; is the maximum water lock capacity; is the effective absorption area; This is the time to reach the maximum water lock amount.

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

6. A method for testing the water-locking performance of a nursing pad according to claim 1, characterized in that: In step S4, the three-level evaluation system includes: Level I indicators: absorption speed, maximum water lock capacity, water retention capacity; Level II indicators: water lock stability and re-seepage index under pressure disturbance; Level III indicators: critical failure pressure, leakage risk coefficient; The permeation rate was verified by modifying the Darcy equation.

7. A method for testing the water-locking performance of a nursing pad according to claim 6, characterized in that: The calculation formula of the re-infiltration index is: ； in, is the refiltration index; is the initial dry weight; is the weight after pressure is released; The calculation formula of the leakage risk coefficient is: ； in, is the leakage risk factor; It is the total leakage during the whole test process; is the maximum water lock capacity; The modified Darcy equation is: ； in, is the liquid penetration rate; is the material permeability; is the liquid viscosity; is the pressure gradient; is the density of the liquid; is the acceleration due to gravity; is the material strain correction term, and its calculation formula is: ;in, , ; is the material compressive strain, , is the thickness compression, is the initial thickness.

8. A detection device based on the method for detecting the water-locking performance of a nursing pad according to any one of claims 1 to 7, characterized in that: include: An equipment rack, a test bench mounted on top of the equipment rack, a fixing rack, and a control system for automatically testing the water-locking performance of the nursing pad using a controller; A sample slot is provided on the top of the testing platform, and a clamping mechanism for fixing the nursing pad sample is installed on the testing platform; a hydraulic cylinder is fixed on the top of the fixing frame, a pressing plate is provided at the bottom of the hydraulic cylinder, and a connection limit mechanism for transmitting the feed amount of the hydraulic cylinder is provided between the hydraulic cylinder and the pressing plate; A plurality of tie rod cylinders are installed on the pressing plate, a pressure head is fixed on the output end of the tie 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 outlet heads are installed at the bottom of the pressing plate, a liquid injection channel is opened inside the pressing plate, and an infusion head for connecting an external infusion device to supply the test solution is fixed on the side of the pressing plate.

9. The testing device for the method for testing the water-locking performance of a nursing pad according to claim 8, characterized in that: The clamping mechanism includes: a plurality of threaded holes opened on the top of the test platform, adjustment bolts threadedly connected to the inner sides of the threaded holes, and a connecting block rotatably connected to the side of the adjusting bolt; a pressing piece is fixed to the bottom of the connecting block.

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

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