Process for the preparation of a diaper backsheet

Abstract

The application belongs to the technical field of diaper base film, and particularly relates to a preparation process of a diaper base film, which comprises the following steps: Step 1: preparing an intermediate barrier film: raw materials: the main component is modified polyethylene, and sheet-shaped nano clay and hydrophobic fumed silica are added; production: resin and nano filler are melt blended in a double-screw extruder, and then granulated; forming: a continuous film with a compact thickness of 3-8 microns is formed through a flow casting method to form the intermediate barrier film. The preparation process of the diaper base film is provided with a detection system, millisecond-level space-time correlation between visual defect identification and micro-needle process signals is achieved, root cause diagnosis of micropore defects is realized, equipment failure and material abnormalities can be accurately distinguished, and the troubleshooting efficiency is greatly improved. Furthermore, the system establishes a signal-quality prediction model through machine learning, and can issue a preventive early warning in an early stage when micro-needle performance degradation has not yet caused visible defects.

Description

Technical Field

[0001] This invention relates to the field of diaper bottom film technology, and in particular to a preparation process for diaper bottom film. Background Technology

[0002] As a core component of disposable hygiene products, the bottom film of diapers must maintain good breathability while absolutely preventing liquid leakage to ensure user comfort. To achieve this contradictory requirement, one advanced technological solution is to fabricate an array of micron-sized (e.g., 5-20 micrometers) pores on a polymer film (i.e., the intermediate barrier film). These micropores allow water vapor to pass through but block liquid water through capillary action. Microneedle roller perforation technology has become the mainstream process for fabricating such precision micropores due to its high efficiency and good pore shape consistency.

[0003] However, quality control in the microneedle perforation process remains a challenge for the industry. Wear, blockage, breakage, or uneven pressure of the microneedles, as well as minute fluctuations in the film raw materials, can directly lead to defects such as pore size deviation, shape distortion, or even complete absence of micropores. These defects can severely impair the function of the substrate membrane, either resulting in insufficient air permeability or triggering leakage risks. Therefore, 100% online inspection of perforation quality is crucial.

[0004] Currently, the industry primarily relies on machine vision-based online inspection systems to detect the perforation quality of such membrane materials. However, existing technologies have the following significant drawbacks, limiting the effectiveness and depth of quality control:

[0005] The disconnect between detection and cause analysis leads to superficial solutions: Existing systems typically only use industrial cameras to photograph thin films and analyze the images to identify the size, shape, and presence of micropores. This approach only "sees" the superficial results of defects (such as small or absent pores) but cannot determine the root cause. For example, if a "missing pore" is detected, the system cannot distinguish whether it is due to the breakage of a specific microneedle or the presence of impurities or uneven thickness in the film at that location leading to puncture failure. This lack of causal understanding makes subsequent process adjustments and equipment maintenance untargeted, resulting in only general shutdowns for troubleshooting and low efficiency.

[0006] Limited information dimensions and insufficient early warning capabilities: Current detection relies solely on visual information, making it a "post-incident detection." The system only issues an alarm when defects have already manifested on the product. It cannot detect the health status of the microneedles themselves (such as pressure decay due to slight wear) or abnormalities in the puncture process (such as impact from foreign objects). Therefore, the system lacks predictive maintenance capabilities, cannot issue warnings before microneedle performance deteriorates and causes mass scrap, and cannot prevent the continuous generation of defects.

[0007] Data isolation hinders intelligent decision-making: Visual inspection data and equipment physical status data (such as microneedle pressure and vibration) typically belong to different systems and are independent of each other, without effective spatiotemporal correlation and fusion analysis. This results in the massive amounts of data generated during the production process not being fully utilized, making it impossible to accurately locate fault sources through cross-validation of multi-source data, and also preventing the establishment of deep correlation models between process parameters, equipment status, and final product quality, thus limiting the development of production towards intelligent and adaptive control. Summary of the Invention

[0008] To address the technical problems of existing diaper bottom film manufacturing processes, such as the disconnect between detection and cause analysis, superficial treatment, limited information dimensions, insufficient early warning capabilities, isolated data, and inability to achieve intelligent decision-making, this invention proposes a new diaper bottom film manufacturing process.

[0009] The present invention proposes a process for preparing a diaper bottom film, comprising step one: preparing an intermediate barrier film.

[0010] Raw materials: The main component is modified polyethylene, mixed with layered nano-clay and hydrophobic fumed silica;

[0011] Production: The resin and nanofiller are melt-blended and granulated in a twin-screw extruder;

[0012] Forming: A dense, continuous film with a thickness of 3-8 micrometers is formed by casting to create an intermediate barrier film;

[0013] Step 2: Prepare the outer and inner layers:

[0014] Outer layer: A polytetrafluoroethylene stretched microporous membrane is used, which is pre-stretched to form an interconnected microporous network with a pore size of 0.1-1.0 μm;

[0015] Inner layer: Made of hydrophilic ultrafine denier spunbond nonwoven fabric;

[0016] Step 3: The intermediate barrier membrane is perforated using a microneedle roller device to form an array of micro-ventilation holes with a pore size of 5-20 micrometers on the intermediate barrier membrane.

[0017] Step 4: The intermediate barrier membrane with micro-vents is first composited with the inner layer by low-temperature hot pressing to obtain a semi-finished composite layer;

[0018] Step 5: The semi-finished composite layer and the outer layer are bonded together by low-temperature hot pressing to obtain the diaper bottom film.

[0019] Preferably, the microneedle roller device in step three includes a fabric conveying component, and the outer surface of the fabric conveying component is provided with a microneedle component, the microneedle component including microneedles, the microneedles making micro-holes in the intermediate barrier membrane;

[0020] It also includes a detection system, which comprises an imaging acquisition and quality detection unit, a microneedle state sensing unit, a multi-source information fusion diagnostic unit, and a control and output unit.

[0021] Preferably, the microneedle component further includes a support bracket, which is fixedly installed on the upper surface of the frame of the fabric conveying component. A lifting hydraulic cylinder is fixedly installed on the outer surface of the support bracket. A protective shell is fixedly installed on one end of the piston rod of the lifting hydraulic cylinder. A micro hydraulic cylinder is fixedly installed on the inner wall of the protective shell. A mounting bracket is fixedly installed on the piston rod of the micro hydraulic cylinder. A sliding plate is slidably inserted into the inner wall of the mounting bracket. The lower surface of the sliding plate is fixedly installed with one end of multiple sets of microneedles.

[0022] A pressing frame is slidably inserted into the outer surface of the mounting bracket via a connecting rod. A connecting spring is fixedly installed on the upper surface of the pressing frame. One end of the connecting spring is fixedly installed to the lower surface of the mounting bracket. One end of the microneedle passes through the lower surface of the protective shell and slidably inserts into the hole wall of the pressing frame.

[0023] Preferably, a support shell is fixedly installed on the outer surface of the frame of the fabric conveying component, a pressing cone groove is slidably inserted into the hole wall of the support shell, the inner wall of the pressing cone groove contacts one end of the micro needle after descent, a contact plate is fixedly installed on the lower surface of the pressing cone groove, a return spring is fixedly installed on the outer surface of the pressing cone groove, and one end of the return spring is fixedly installed with the hole wall of the support shell.

[0024] Preferably, the imaging acquisition and quality inspection unit is used to acquire images of the perforated film online and identify and classify micropore defects;

[0025] The microneedle status sensing unit is used to collect pressure signals when the microneedle performs the piercing action in real time and monitor the working status of the microneedle.

[0026] The multi-source information fusion diagnostic unit is connected to the imaging acquisition and quality detection unit and the microneedle state sensing unit, respectively. It is used to receive micropore defect information and microneedle state information, and through spatiotemporal correlation and logical analysis, determine whether the generation of a specific defect is caused by abnormal microneedle state, and output the root cause diagnosis result.

[0027] The control and output unit is used to display, alarm, or trigger corresponding maintenance control commands based on the root cause diagnosis results.

[0028] Preferably, the imaging acquisition and quality detection unit includes an industrial camera, a telecentric lens, a parallel backlight, and a synchronous triggering module;

[0029] The industrial camera is fixedly mounted on the outer surface of the frame of the fabric conveying component via a support bracket, the parallel backlight is fixedly mounted on the outer surface of the frame of the fabric conveying component, and the telecentric lens is fixedly mounted on the outer surface of the industrial camera.

[0030] The parallel backlight and the industrial camera are positioned on opposite sides of the thin film to form a backlight imaging optical path; the synchronous trigger module is used to control the camera to capture images and ensure that the images are synchronized with the production cycle.

[0031] Preferably, the microneedle status sensing unit includes a pressing pressure sensor installed on the inner wall of the pressing frame and a piezoelectric sensor installed on the inner bottom wall of the support housing and located directly below the contact plate;

[0032] The pressing pressure sensor is used to measure the dynamic pressure curve of a single piercing process, and the piezoelectric sensor is used to measure the steady-state force transmitted by the needle tip through the pressing cone groove and the contact plate.

[0033] The microneedle status sensing unit extracts the pressure peak, pressure curve integral area and steady-state pressure value for each piercing action in real time, compares them with the preset normal benchmark model, and outputs the microneedle status assessment. The assessment results include normal, worn, suspected blockage or failure.

[0034] Preferably, the multi-source information fusion diagnostic unit includes a data spatiotemporal alignment module and a root cause analysis logic module;

[0035] The data spatiotemporal alignment module is used to accurately match the time point and lateral position of the defect hole detected by the imaging acquisition and quality detection unit with the microneedle (26) status information acquired by the microneedle status sensing unit at the same spatiotemporal point, based on the production line speed and encoder signal.

[0036] The root cause analysis logic module has the following pre-defined diagnostic rules:

[0037] Rule A: If a defect of missing or too small aperture is detected at a certain location and the peak pressure of the microneedle (26) matched in this time is significantly lower than the normal threshold, the root cause is insufficient pressure of the corresponding microneedle (26) or wear and breakage.

[0038] Rule B: If a defect of excessively large aperture or tear is detected, and the matched steady-state pressure value is abnormally increased, the diagnostic root cause is that the corresponding microneedle (26) is blocked or encounters a foreign object, resulting in an abnormally increased puncture force.

[0039] Rule C: If a defect is detected, but the peak pressure and steady-state pressure data of the matched microneedle (26) are completely normal, the root cause is diagnosed as abnormal film raw materials or external contamination, and equipment failure is ruled out.

[0040] Preferably, the imaging acquisition and quality detection unit further includes an image processing and analysis module, which performs the following process:

[0041] Preprocessing and micro-hole target segmentation of the acquired images;

[0042] Calculate the equivalent diameter and roundness of each micropore;

[0043] According to the preset aperture range With roundness threshold Perform a pass / fail assessment and classify unqualified holes as follows: hole diameter too small / blocked, hole diameter too large / torn, poor shape, or missing hole;

[0044] Record the position coordinates of each defective hole in the film width direction or its timing number relative to the start point of the production line.

[0045] Preferably, the multi-source information fusion diagnostic unit further includes a statistical learning module;

[0046] The statistical learning module is used to collect and correlate defect data and microneedle status data over a long period of time. Through machine learning, it analyzes the correlation between microneedle status parameters and the incidence of specific types of defects, and establishes a predictive model to issue preventive maintenance warnings in advance before microneedle performance deteriorates to the point of causing apparent defects.

[0047] The control and output unit includes:

[0048] The integrated display interface is used to display micropore quality distribution cloud maps, microneedle pressure state maps, and root cause localization maps after fusion diagnosis in parallel or overlay.

[0049] The graded alarm module is used to trigger different levels of alarms based on the severity of the root cause diagnosis results. Among them, equipment failure diagnosed by rule A or B triggers a high-level shutdown and maintenance alarm, and material problems diagnosed by rule C trigger a medium-level process parameter adjustment alarm.

[0050] The maintenance command interface is used to output commands to the equipment PLC when a specific microneedle abnormality is diagnosed, prompting or automatically locating the abnormal workstation for replacement or cleaning.

[0051] The beneficial effects of this invention are as follows:

[0052] 1. By setting up a microneedle roller component and controlling the step-by-step sequence of the pressing frame and microneedles within the microneedle component—pressing before puncturing and retracting the needle before releasing the pressure—precision and reliability of the piercing process are achieved. This design ensures that the film is stably compressed at the moment of piercing, effectively preventing the film from sticking or shifting with the needle, thus forming precisely positioned and neatly edged micropores on the ultrafilm. Combined with real-time monitoring of the pressure of each action by built-in sensors, this system not only improves the consistency of piercing quality but also provides core data for predictive maintenance and process optimization through the digitization of process signals.

[0053] 2. By setting up a detection system and establishing millisecond-level spatiotemporal correlation between visual defect recognition and microneedle process signals, the root cause diagnosis of micropore defects is achieved. This system can accurately distinguish between equipment failure and material abnormality, greatly improving troubleshooting efficiency. Furthermore, the system establishes a "signal-quality" prediction model through machine learning, which can issue preventive warnings in the early stages before microneedle performance degradation leads to visible defects. This promotes a shift in quality control from post-event rejection to pre-event prevention, significantly improving the level of production intelligence and quality stability. Attached Figure Description

[0054] Figure 1 This is a schematic diagram of the preparation process of a diaper bottom film proposed in this invention;

[0055] Figure 2 This is a perspective view of the protective shell structure of a diaper bottom film manufacturing process proposed in this invention;

[0056] Figure 3 This is a perspective view of the micro hydraulic cylinder structure used in the preparation process of a diaper bottom film proposed in this invention.

[0057] Figure 4 This is a perspective view of the mounting frame structure for the preparation process of a diaper bottom film proposed in this invention;

[0058] Figure 5 This is a three-dimensional view of the microneedle structure of a diaper bottom film preparation process proposed in this invention;

[0059] Figure 6 This is a perspective view of the supporting shell structure for the preparation process of a diaper bottom film proposed in this invention;

[0060] Figure 7 This is a perspective view of the pressing cone groove structure in the preparation process of a diaper bottom film proposed in this invention;

[0061] Figure 8 This is a three-dimensional view of the industrial camera structure used in the preparation process of a diaper bottom film proposed in this invention.

[0062] Figure 9This is a flowchart of a detection system for the preparation process of a diaper bottom film proposed in this invention.

[0063] In the diagram: 1. Fabric conveying component; 2. Support bracket; 21. Lifting hydraulic cylinder; 22. Protective housing; 23. Miniature hydraulic cylinder; 24. Mounting bracket; 25. Slide plate; 26. Micro needle; 3. Pressing frame; 31. Connecting spring; 4. Support housing; 41. Pressing cone groove; 42. Contact plate; 43. Return spring; 5. Industrial camera; 51. Telecentric lens; 52. Parallel backlight; 6. Pressing pressure sensor; 61. Piezoelectric sensor. Detailed Implementation

[0064] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0065] Example 1

[0066] Reference Figures 1-8 A manufacturing process for a diaper bottom film includes step one: preparing an intermediate barrier film.

[0067] Raw materials: The main component is modified polyethylene, mixed with layered nano clay and hydrophobic fumed silica.

[0068] Production: The resin and nanofiller are melt-blended and granulated in a twin-screw extruder.

[0069] Forming: A dense, continuous film with a thickness of 3-8 micrometers is formed by casting to create an intermediate barrier film.

[0070] Step 2: Prepare the breathable and skin-friendly outer and inner layers:

[0071] Outer layer: A polytetrafluoroethylene stretched microporous membrane is used, which is pre-stretched to form an interconnected microporous network with a pore size of 0.1-1.0 μm.

[0072] Inner layer: made of hydrophilic ultrafine denier spunbond nonwoven fabric.

[0073] Step 3: Use a microneedle roller device to perforate the intermediate barrier membrane to form an array of micro-ventilation holes with a diameter of 5-20 micrometers on the intermediate barrier membrane.

[0074] Step 4: The intermediate barrier membrane with micro-vents is bonded to the inner layer by low-temperature hot pressing to form a first composite layer, resulting in a semi-finished composite layer.

[0075] Step 5: The semi-finished composite layer and the outer layer are bonded together a second time by low-temperature hot pressing to obtain the diaper bottom film.

[0076] The microneedle 26-roller equipment in step three includes a fabric conveying component 1, which forms the base and conveying platform of the equipment. Its core is a robust frame structure, internally integrating a precision guide roller system. The intermediate barrier film to be perforated is drawn out by the unwinding device and tensioned, corrected, and conveyed at a uniform speed via this guide roller system. The frame provides the mounting reference for all other functional components, ensuring a precise spatial relationship between the microneedle 26 components, detection unit, etc., and the intermediate barrier film conveying path. The conveying speed is driven by a servo motor and synchronized with the overall production line cycle.

[0077] The outer surface of the fabric conveying component 1 is provided with microneedles 26. The microneedles 26 are functional assemblies that generate the perforation action. They are rigidly fixed to the upper surface of the frame of the fabric conveying component 1 and are located directly above the conveying path of the intermediate barrier film. This component adopts a multi-layer drive and buffer design, and its specific structure is as follows:

[0078] Support bracket 2: It is a gantry or column-type rigid structure, and its bottom is firmly installed on the frame of the fabric conveying component 1 by high-strength bolts, providing stable support for the entire micro needle 26 component.

[0079] Lifting hydraulic cylinder 21: Its cylinder body is vertically fixed to the top crossbeam or side wall of the support bracket 2. This hydraulic cylinder serves as the primary drive source, responsible for achieving the "coarse positioning" lifting of the entire microneedle 26 component. In non-working state or during replacement and maintenance, it lifts the entire puncture unit to a safe height; in working state, it drives it to descend to a preparatory position close to the membrane.

[0080] Protective housing 22: A hollow rigid housing connected to the end of the piston rod of the lifting hydraulic cylinder 21. It houses a precision puncture actuator inside and serves to prevent dust, protect internal components, and guide airflow on the outside.

[0081] Miniature hydraulic cylinder 23: Fixedly installed on the top of the inner cavity of the protective housing 22. As a secondary drive source, it is responsible for driving the internal puncture mechanism to perform high-frequency, short-stroke precision reciprocating motion after the lifting hydraulic cylinder 21 completes the coarse positioning. It is the direct source of puncture force.

[0082] Mounting bracket 24: A plate-like or frame-like structure that is fixedly connected to the end of the piston rod of the micro hydraulic cylinder 23 and moves vertically together with the piston rod. It is the final support component of the micro needle 26.

[0083] Slide 25 and microneedle 26 array: Slide 25 is slidably inserted into the inner cavity of mounting bracket 24 via linear guide rail or precision guide post pair, which facilitates the replacement of microneedles 26. The upper ends of multiple sets of microneedles 26 (usually arranged in an array) are vertically fixed to the lower surface of slide 25. The microneedles 26 are made of high hardness and high wear resistance material (such as tungsten carbide), and the needle tips are precision ground.

[0084] Pressing frame 3 and connecting spring 31: Pressing frame 3 is an independent flat plate located directly below mounting frame 24. It is slidably connected to mounting frame 24 through several vertical connecting rods. Connecting spring 31 is sleeved on the connecting rods, with its two ends abutting against the lower surface of mounting frame 24 and the upper surface of pressing frame 3, respectively. Precision guide holes corresponding one-to-one with the positions of micro needles 26 are opened on pressing frame 3. The lower section of micro needle 26 can slide through these guide holes. In the natural state, the elastic force of connecting spring 31 makes pressing frame 3 in the lowest position relative to mounting frame 24. At this time, the tip of micro needle 26 retracts into the guide hole.

[0085] Support shell 4: It is fixedly installed on the lower surface of the frame of the fabric conveying component 1, and forms a guide chamber inside.

[0086] Pressing conical groove 41: A module that can slide vertically within the guide hole wall of the supporting housing 4. Its upper surface is a conical groove that contacts the tip of the microneedle 26, but the tip of the microneedle 26 does not contact the pressing conical groove 41, thus protecting the tip of the microneedle 26. Its lower surface is rigidly connected to a contact plate 42. The upper surface of the contact plate 42 is flat, and the pressing conical groove 41 pushes the contact plate 42 down.

[0087] Return spring 43: It is sleeved on the outside of the pressing cone groove 41. One end acts on the flange of the pressing cone groove 41, and the other end acts on the supporting shell 4, providing an upward return force for the pressing cone groove 41. When the micro needle 26 is pressed down, the pressing cone groove 41 moves down against the force of the return spring 43. After the micro needle 26 is withdrawn, the return spring 43 pushes the pressing cone groove 41 and the contact plate 42 back to the upper limit position.

[0088] Example 2

[0089] like Figure 9 As shown, in order to detect the micropores pierced by the microneedles 26 on the intermediate barrier membrane, a detection system was set up. The detection system includes an imaging acquisition and quality detection unit, a microneedle state sensing unit, a multi-source information fusion diagnostic unit, and a control and output unit.

[0090] Specifically, the imaging acquisition and quality inspection unit is used to acquire images of perforated films online and identify and classify micropore defects.

[0091] The microneedle status sensing unit is used to collect pressure signals in real time when the microneedle 26 performs the piercing action and monitor the working status of the microneedle 26.

[0092] The multi-source information fusion diagnostic unit is connected to the imaging acquisition and quality detection unit and the microneedle 26 state sensing unit, respectively. It is used to receive micropore defect information and microneedle 26 state information. Through spatiotemporal correlation and logical analysis, it determines whether the occurrence of a specific defect is caused by the abnormal state of the microneedle 26 and outputs the root cause diagnosis result.

[0093] The control and output unit is used to display, alarm, or trigger corresponding maintenance control commands based on the root cause diagnosis results.

[0094] Specifically, the imaging acquisition and quality inspection unit includes an industrial camera 5, a telecentric lens 51, a parallel backlight 52, and a synchronous triggering module.

[0095] This unit employs a strategy combining a telecentric optical system with parallel backlighting to ensure high-precision imaging. A high-resolution industrial camera 5, equipped with a telecentric lens 51, is mounted perpendicular to the thin film plane. A parallel backlight 52 is positioned opposite the thin film. In transmitted light imaging, the micro-aperture area appears bright due to light transmission, while the intact film area appears dark, thus obtaining a high-contrast original image. A synchronous trigger module receives encoder signals from the production line, achieving strict synchronization between image acquisition and thin film feeding, ensuring that each frame corresponds to a specific physical position.

[0096] The image processing and analysis module executes the following algorithm chain: First, Gaussian filtering and CLAHE contrast-limited adaptive histogram equalization preprocessing are performed; second, template matching based on prior array parameters is used to locate all theoretical pore locations (ROIs); then, within each ROI, Canny edge detection combined with Otsu adaptive thresholding is used to accurately segment the binarized connected regions of a single micropore.

[0097] Feature quantization calculation: For each segmented micropore connected region, calculate its key geometric features.

[0098] 1. Equivalent diameter, used to determine whether the aperture is within the standard range (5-20μm), is calculated using the following formula: ,in, This is the equivalent diameter of the micropore, expressed in micrometers. It is a direct measure for determining whether the pore size is acceptable (5-20 μm). In an image, this refers to the pixel area occupied by a single micropore's connected region, which is the total number of pixels contained in that region. The spatial calibration factor, measured in micrometers per pixel, is calculated by photographing a standard calibration board of known size, determining the length represented by each pixel in actual physical space. Pi is a mathematical constant, approximately equal to 3.14159.

[0099] 2. Circularity, used to quantify the degree to which the shape of a micropore approaches a perfect circle, is calculated using the following formula: ,in, The circularity of the micropores, ranging from (0,1]. Let be the pixel perimeter of the micro-hole connected region.

[0100] Acceptance judgment and classification: based on the preset aperture tolerance zone and shape tolerance threshold Perform a double check. Only if... ≤ ≤ and ≥ If both conditions are met, the micropore is deemed acceptable; otherwise, it is deemed defective, and the specific rule violated will be applied accordingly. < or < They are classified as "orifice too small / blocked", "orifice too large / torn", "poor shape" or "missing orifice", and their location coordinates are recorded. This is the lower limit of the acceptable standard for micropore diameter. This represents the upper limit of the acceptable pore size standard for micropores. This is the minimum threshold for the micropores to be round and spherical.

[0101] Specifically, the microneedle status sensing unit includes a pressing pressure sensor 6 installed on the inner wall of the pressing frame 3 and a piezoelectric sensor 61 installed on the inner bottom wall of the support housing 4 and located directly below the contact plate 42.

[0102] The pressing pressure sensor 6 is used to measure the dynamic pressure curve of a single piercing process, and the piezoelectric sensor 61 is used to measure the steady-state force transmitted by the needle tip through the pressing cone groove 41 and the contact plate 42.

[0103] The microneedle status sensing unit receives raw signals from the pressure sensor 6 and the piezoelectric sensor 61 in real time. The signals are filtered (e.g., bandpass filtering to remove power frequency interference), amplified, and converted by an AD converter through a signal conditioning circuit. The feature extraction engine analyzes the signals in each piercing cycle and extracts peak force, such as the pressure curve. The system extracts the force-time curve integral (impulse) and pressure rise time; simultaneously, it extracts the steady-state pressure signal features from the piezoelectric sensor 61, namely the final force value of the microneedle tip 26. The real-time extracted dynamic and steady-state pressure features are combined into a feature vector, which is compared with the pre-stored benchmark feature model library (containing typical features of new needles, normally worn needles, partially blocked needles, and broken needles) to initially output the "health status index" and "abnormal type identifier" of each microneedle.

[0104] The microneedle status sensing unit receives raw signals from the pressure sensor 6 and the piezoelectric sensor 61 in real time. and The signal is then filtered, amplified, and converted via an analog-to-digital converter (ADC) circuit. The steady-state force transmitted from the needle tip to the piezoelectric sensor 61 through the pressing conical groove 41 is characterized.

[0105] Feature extraction engine: Analyzes the signal within each piercing cycle and extracts the following time-domain feature vectors. :

[0106] 1. Time-domain characteristics of pressure signals:

[0107] Assume that during a single piercing process, the time-domain signal collected by the pressure sensor 6 is... The sampling interval is , of which time.

[0108] Peak force : , This reflects the maximum puncture force, among which, This is a pressure-time function, representing the pressure signal collected by pressure sensor 6 as a function of time. This represents the start time of a single perforation pressure signal. This represents the end time of a single perforation pressure signal.

[0109] Impulse (force-time integral) : It reflects the overall effect of the puncture process.

[0110] Pressure rise time : ,in, For the pressure to reach the threshold The moment reflects the speed of action response. The pressure threshold used to calculate rise time is typically set as a certain percentage (e.g., 10%) of the peak force. , To reach peak pressure At that moment.

[0111] 2. Steady-state pressure characteristics: Steady-state pressure value , ,in, This value represents the initial moment when the signal enters the stable plateau; it directly reflects the final force exerted by the needle tip. To obtain the arithmetic mean.

[0112] Preliminary state assessment: The feature vectors extracted in real time... The model is compared with a pre-stored baseline feature model library to output the "health status index" and preliminary abnormality indicators for each microneedle.

[0113] Specifically, the multi-source information fusion diagnostic unit includes a data spatiotemporal alignment module and a root cause analysis logic module;

[0114] The data spatiotemporal alignment module, as a prerequisite for data fusion, utilizes a unified high-precision time base (such as the PTP protocol) to associate and bind the absolute timestamp and lateral coordinate of a defect detected by the vision system with the microneedle 26 action signal features of the microneedle 26 state perception system at the same timestamp and corresponding lateral coordinate position at millisecond level.

[0115] Data spatiotemporal alignment module: Utilizes a unified time base and encoder signals to locate defects detected visually. It is precisely correlated in time with the action signal of the corresponding microneedle.

[0116] Root cause analysis logic module: Embedded with an expert system based on quantification rules, assuming the real-time peak force of the microneedle 26 associated with a certain defect location is... Real-time steady-state pressure is The average values ​​corresponding to the historical normal values ​​of microneedling 26 are as follows: , Standard deviation is , The confidence coefficient is Typically, 2-3 is chosen, and the diagnostic logic is as follows:

[0117] Rule A: If in satisfy; < and If so, the diagnosis is insufficient pressure on the microneedle 26 or wear / broken needle.

[0118] Rule B: If the defect is "excessive aperture / tear" and The diagnosis was "foreign objects or partial blockage at the tip of the microneedle 26, resulting in an abnormally increased squeezing and puncture force".

[0119] Rule C: If a defect is detected, but the associated... and All are within the normal range. If the thickness is uneven, there are internal defects or surface contamination in the thin film raw material at this location, then the diagnosis is "the thin film raw material has uneven thickness, internal defects or surface contamination at this location".

[0120] Statistical Learning and Prediction Module: This module is a self-evolving component of the system. It continuously collects long-term paired data of "process signal characteristics - micropore quality results" and uses machine learning algorithms such as random forest, gradient boosting tree or temporal neural network to train a prediction model. This model can learn the implicit correlation between the slow drift trend of microneedle signal characteristics (such as a 1% decrease in pressure peak per week) and the probability of the occurrence of specific defects in the future (such as a decrease in roundness), thereby achieving predictive maintenance and issuing a replacement warning before the performance of microneedles degrades to the point of causing apparent defects.

[0121] Statistical Learning and Prediction Module: This module uses machine learning algorithms to build a predictive model of the state characteristics of microneedles 26 and future quality risks. Essentially, it learns a mapping function from historical feature sequences to future defect rates. : ,in, The historical feature vector is the prediction model function trained by the machine learning algorithm. Trend features (such as mean and variance) are extracted from recent historical data.

[0122] Peak force sliding average : ,in, For the first in the window Peak force of secondary perforation This refers to the number of times a single piercing event is sampled within a continuous time period or a continuous sequence of piercing events.

[0123] Pressure rise time variance : ,in, For the first Pressure rise time during secondary perforation. For this window arithmetic mean .

[0124] Mean steady-state pressure : ,in, To be within the statistical analysis window, the first The steady-state pressure value measured by the piezoelectric sensor 61 during the secondary perforation event represents the final force of a single perforation.

[0125] Steady-state pressure variance : .

[0126] Model The system can be trained using algorithms such as gradient boosting decision trees. When the predicted risk level exceeds the threshold, the system will issue a preventative maintenance warning to achieve pre-emptive intervention.

[0127] The control and output unit includes:

[0128] Comprehensive display interface: Presents a quality map (using color to represent orifice distribution), pressure cloud map (using color to represent the pressure status of each needle), and root cause localization map (highlighting the specific needle location diagnosed as a defect caused by equipment) in a graphical manner.

[0129] The graded early warning and decision support module triggers three levels of early warning based on the root cause diagnosis results and the output of the prediction module. Level 1 (Early Warning): Notifies users that "the performance of microneedle 26 is showing a deteriorating trend; a shutdown for inspection is recommended next time." Level 2 (Alarm): Notifies users that "microneedle 26 is in an abnormal state, affecting quality; planned replacement is recommended." Level 3 (Severe Alarm and Linkage): Issues a signal stating "microneedle 26 has failed, causing continuous defects," and can directly send a command to the equipment PLC to trigger a shutdown or mark the needle position as disabled.

[0130] Data traceability and process optimization interface: Stores all raw data and diagnostic logs, supports in-depth traceability analysis by batch, time, and fault type, and provides data closed-loop feedback for the optimization of process parameters (such as puncture pressure and speed).

[0131] Working principle: First stage: Raw material preparation

[0132] Preparation of intermediate barrier film: Modified polyethylene resin, layered nano-clay, and hydrophobic fumed silica are melt-blended and granulated in a twin-screw extruder, and then a continuous film with a thickness of 3-8 micrometers is produced by casting.

[0133] Prepare the composite layer: Prepare the upper layer (polytetrafluoroethylene stretched microporous membrane) and the lower layer (hydrophilic ultrafine denier spunbond nonwoven fabric).

[0134] Phase Two: Microneedle 26 Precision Drilling and Online Detection

[0135] Film conveying and positioning: The rolled intermediate barrier film is precisely and uniformly pulled by the fabric conveying component 1 and passes through the micro needle 26 station.

[0136] The 26 components of the microneedle operate in sequence:

[0137] Pressing Stability: The lifting hydraulic cylinder 21 drives the entire microneedle 26 component to descend. The micro hydraulic cylinder 23 drives the mounting bracket 24 to descend, first causing the pressing bracket 3 to contact and press the film onto the contact plate 42 below, compressing the connecting spring 31.

[0138] Precise puncture: As the mounting bracket 24 continues to descend, it overcomes the elasticity of the connecting spring 31, causing the array of microneedles 26 fixed on the slide plate 25 to extend out of the pressing bracket 3, vertically piercing the film, and the needle tip finally abuts against the inner wall of the pressing cone groove 41.

[0139] Signal sensing: During the puncture, the pressure sensor 6 is pressed to collect the pressure curve in real time. Simultaneously, the needle tip pushes the pressing cone groove 41 downward, and the contact plate 42 presses the piezoelectric sensor 61 directly below, generating and transmitting a steady-state pressure signal characterizing the final force of the needle tip. .

[0140] Anti-adhesion reset: The mounting bracket 24 rises, the micro needle 26 retracts into the pressing bracket 3 first, then the pressing bracket 3 separates from the film surface, and the pressing cone groove 41 is reset under the action of the reset spring 43.

[0141] Parallel online detection and diagnosis:

[0142] Visual acquisition: Downstream of the perforation point, industrial camera 5 performs backlight imaging on the perforated film under the control of the synchronous trigger module.

[0143] Image processing: The imaging acquisition and quality inspection unit processes the image and calculates the equivalent diameter of each micropore. and roundness To determine compliance and classify defects.

[0144] State sensing: The microneedle 26 state sensing unit processes sensor signals and extracts peak force. Ascent time Steady-state pressure value Features such as...

[0145] Fusion Diagnosis: The data spatiotemporal alignment module of the multi-source information fusion diagnosis unit accurately binds the location of visual defects with the corresponding microneedle motion signals, and the root cause analysis logic module outputs diagnostic results according to rules.

[0146] Prediction and Early Warning: The statistical learning and prediction module analyzes historical characteristics and trends to predict the risk of performance degradation of the Microneedle 26 in advance.

[0147] Phase Three: Layered Composite

[0148] First composite: The perforated intermediate barrier membrane is bonded to the lower skin-friendly non-woven fabric through low-temperature hot pressing to form a semi-finished product.

[0149] The second composite process involves bonding the semi-finished product with the upper breathable membrane using low-temperature hot pressing to ultimately produce a three-layer composite diaper bottom film.

[0150] Phase Four: Monitoring, Feedback, and Decision Implementation

[0151] Information integration and display: The integrated display interface of the control and output unit displays the quality map, microneedle 26 pressure cloud map and root cause localization map in real time.

[0152] Tiered decision-making intervention:

[0153] If the diagnosis result is "abnormal film raw materials", a medium-level alarm will be triggered, prompting a check of process parameters.

[0154] If the diagnosis result is "microneedle 26 wear / blockage", an advanced alarm is triggered, the maintenance command interface outputs positioning information, and prompts to replace the microneedle 26 in a specific location.

[0155] If the prediction module outputs a high-risk warning, triggering a Level 1 warning, planned maintenance is recommended.

[0156] If a series of serious defects occur, the system can send a command to the equipment PLC to trigger an automatic shutdown.

[0157] Phase 5: Data Closed Loop

[0158] Data traceability and optimization: All process data is stored in the data storage module for quality traceability and provides data support for optimizing process parameters such as piercing pressure and speed, forming a closed loop of production-inspection-optimization.

[0159] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A manufacturing process for a diaper bottom film, characterized in that: Including step one: preparing the intermediate barrier mold: Raw materials: The main component is modified polyethylene, mixed with layered nano-clay and hydrophobic fumed silica; Production: The resin and nanofiller are melt-blended and granulated in a twin-screw extruder; Forming: A dense, continuous film with a thickness of 3-8 micrometers is formed by casting to create an intermediate barrier film; Step 2: Prepare the outer and inner layers: Outer layer: A polytetrafluoroethylene stretched microporous membrane is used, which is pre-stretched to form an interconnected microporous network with a pore size of 0.1-1.0 μm; Inner layer: Made of hydrophilic ultrafine denier spunbond nonwoven fabric; Step 3: The intermediate barrier membrane is perforated using a microneedle roller device to form an array of micro-ventilation holes with a pore size of 5-20 micrometers on the intermediate barrier membrane. Step 4: The intermediate barrier membrane with micro-vents is first composited with the inner layer by low-temperature hot pressing to obtain a semi-finished composite layer; Step 5: The semi-finished composite layer and the outer layer are bonded together by low-temperature hot pressing to obtain the diaper bottom film.

2. The preparation process of a diaper bottom film according to claim 1, characterized in that: The microneedle roller device in step three includes a fabric conveying component (1), and a microneedle component is provided on the outer surface of the fabric conveying component (1). The microneedle component includes microneedles (26), and the microneedles (26) make micro-perforations in the intermediate barrier membrane. It also includes a detection system, which comprises an imaging acquisition and quality detection unit, a microneedle state sensing unit, a multi-source information fusion diagnostic unit, and a control and output unit.

3. The preparation process of a diaper bottom film according to claim 2, characterized in that: The microneedle component also includes a support bracket (2), which is fixedly installed on the upper surface of the frame of the fabric conveying component (1). A lifting hydraulic cylinder (21) is fixedly installed on the outer surface of the support bracket (2). A protective shell (22) is fixedly installed on one end of the piston rod of the lifting hydraulic cylinder (21). A micro hydraulic cylinder (23) is fixedly installed on the inner wall of the protective shell (22). A mounting bracket (24) is fixedly installed on the piston rod of the micro hydraulic cylinder (23). A sliding plate (25) is slidably inserted into the inner wall of the mounting bracket (24). The lower surface of the sliding plate (25) is fixedly installed with one end of multiple sets of microneedles (26). The outer surface of the mounting bracket (24) is slidably connected to a pressing bracket (3) via a connecting rod. A connecting spring (31) is fixedly installed on the upper surface of the pressing bracket (3). One end of the connecting spring (31) is fixedly installed to the lower surface of the mounting bracket (24). One end of the micro needle (26) passes through the lower surface of the protective shell (22) and is slidably connected to the hole wall of the pressing bracket (3).

4. The preparation process of a diaper bottom film according to claim 3, characterized in that: A support shell (4) is fixedly installed on the outer surface of the frame of the fabric conveying component (1). A pressing cone groove (41) is slidably inserted into the hole wall of the support shell (4). The inner wall of the pressing cone groove (41) contacts one end of the micro needle (26) after it descends. A contact plate (42) is fixedly installed on the lower surface of the pressing cone groove (41). A return spring (43) is fixedly installed on the outer surface of the pressing cone groove (41). One end of the return spring (43) is fixedly installed with the hole wall of the support shell (4).

5. The preparation process of a diaper bottom film according to claim 4, characterized in that: The imaging acquisition and quality inspection unit is used to acquire images of the perforated film online and identify and classify micropore defects. The microneedle status sensing unit is used to collect the pressure signal when the microneedle (26) performs the piercing action in real time and monitor the working status of the microneedle (26). The multi-source information fusion diagnostic unit is connected to the imaging acquisition and quality detection unit and the microneedle state sensing unit respectively. It is used to receive micropore defect information and microneedle (26) state information, and through spatiotemporal correlation and logical analysis, determine whether the generation of a specific defect is caused by the abnormal state of the microneedle (26), and output the root cause diagnosis result. The control and output unit is used to display, alarm, or trigger corresponding maintenance control commands based on the root cause diagnosis results.

6. The preparation process of a diaper bottom film according to claim 5, characterized in that: The imaging acquisition and quality detection unit includes an industrial camera (5), a telecentric lens (51), a parallel backlight (52), and a synchronous triggering module; The industrial camera (5) is fixedly mounted on the outer surface of the frame of the fabric conveying component (1) by a support frame, the parallel backlight (52) is fixedly mounted on the outer surface of the frame support frame of the fabric conveying component (1), and the telecentric lens (51) is fixedly mounted on the outer surface of the industrial camera (5). The parallel backlight (52) and the industrial camera (5) are placed on opposite sides of the thin film to form a backlight imaging optical path; the synchronous trigger module is used to control the camera to capture images and ensure that the images are synchronized with the production cycle.

7. The preparation process of a diaper bottom film according to claim 6, characterized in that: The microneedle status sensing unit includes a pressing pressure sensor (6) installed on the inner wall of the pressing frame (3) and a piezoelectric sensor (61) installed on the inner bottom wall of the support shell (4) and located directly below the contact plate (42). The pressing pressure sensor (6) is used to measure the dynamic pressure curve of a single piercing process, and the piezoelectric sensor (61) is used to measure the steady-state force transmitted by the needle tip through the pressing cone groove (41) and the contact plate (42). The microneedle status sensing unit extracts the pressure peak, pressure curve integral area and steady-state pressure value of each piercing action in real time, and compares them with the preset normal benchmark model to output the status evaluation of the microneedle (26). The evaluation results include normal, worn, suspected blockage or failure.

8. The preparation process of a diaper bottom film according to claim 7, characterized in that: The multi-source information fusion diagnostic unit includes a data spatiotemporal alignment module and a root cause analysis logic module; The data spatiotemporal alignment module is used to accurately match the time point and lateral position of the defect hole detected by the imaging acquisition and quality detection unit with the microneedle (26) status information acquired by the microneedle status sensing unit at the same spatiotemporal point, based on the production line speed and encoder signal. The root cause analysis logic module has the following pre-defined diagnostic rules: Rule A: If a defect of missing or too small aperture is detected at a certain location and the peak pressure of the microneedle (26) matched in this time is significantly lower than the normal threshold, the root cause is insufficient pressure of the corresponding microneedle (26) or wear and breakage. Rule B: If a defect of excessively large aperture or tear is detected, and the matched steady-state pressure value is abnormally increased, the diagnostic root cause is that the corresponding microneedle (26) is blocked or encounters a foreign object, resulting in an abnormally increased puncture force. Rule C: If a defect is detected, but the peak pressure and steady-state pressure data of the matched microneedle (26) are completely normal, the root cause is diagnosed as abnormal film raw materials or external contamination, and equipment failure is ruled out.

9. The preparation process of a diaper bottom film according to claim 8, characterized in that: The imaging acquisition and quality detection unit also includes an image processing and analysis module, which performs the following process: Preprocessing and micro-hole target segmentation of the acquired images; Calculate the equivalent diameter and roundness of each micropore; According to the preset aperture range With roundness threshold Perform a pass / fail assessment and classify unqualified holes as follows: hole diameter too small / blocked, hole diameter too large / torn, poor shape, or missing hole; Record the position coordinates of each defective hole in the film width direction or its timing number relative to the start point of the production line.

10. The preparation process of a diaper bottom film according to claim 9, characterized in that: The multi-source information fusion diagnostic unit also includes a statistical learning module; The statistical learning module is used to collect and associate defect data with microneedle (26) status data over a long period of time. It analyzes the correlation between microneedle (26) status parameters and the occurrence rate of specific types of defects through machine learning, and establishes a prediction model to issue a preventive maintenance warning in advance before the performance of microneedle (26) deteriorates to the point of causing apparent defects. The control and output unit includes: The integrated display interface is used to display micropore mass distribution cloud map, microneedle (26) pressure state map and root cause localization map after fusion diagnosis in parallel or superimposed; The graded alarm module is used to trigger different levels of alarms based on the severity of the root cause diagnosis results. Among them, equipment failure diagnosed by rule A or B triggers a high-level shutdown and maintenance alarm, and material problems diagnosed by rule C trigger a medium-level process parameter adjustment alarm. The maintenance command interface is used to output commands to the equipment PLC when a specific microneedle (26) abnormality is diagnosed, prompting or automatically locating the abnormal workstation for replacement or cleaning.

Images