The elastic adhesive manufacturing process you are interested in actually holds the key technology that ensures sanitary pads fit snugly and remain securely in place. The production of elastic adhesives for sanitary pads is based on Hot Melt Pressure-Sensitive Adhesives (HMPSA); through the precise control of compounding and coating processes, it ensures stable adhesion during high-speed manufacturing operations. The core workflow encompasses: raw material melting → filtration and homogenization → vacuum degassing → precision coating → cooling and setting. Throughout this entire process, strict control must be maintained over the following five critical process parameters:
Heating Temperature: 140°C–170°C (Dynamically Controlled)
Temperature directly influences the fluidity and viscosity of the adhesive. If the temperature is too low, it can result in uneven coating and poor wetting; conversely, if it is too high, it may cause the adhesive to carbonize or damage the substrate material. Real-time adjustments must be made based on the specific adhesive type (e.g., SIS- or EVA-based) and ambient humidity; typically, the temperature is set within the range of 150 ± 10°C, utilizing zone-specific temperature control to ensure uniform melting.
Lamination Pressure: 3 kg–6 kg (Precision Application)
During the lamination stage-where elastic bands are bonded to non-woven fabric-the roller pressure must be maintained stably within the range of 3–6 kg/cm². Insufficient pressure can easily lead to weak adhesion and subsequent delamination; conversely, excessive pressure may crush the elastic material and compromise its three-dimensional structure. Modern equipment frequently employs pneumatic closed-loop control systems to facilitate dynamic pressure compensation.
Production Line Speed: Matched to Coating Response Time
High-speed production lines can reach speeds of 400–600 pieces per minute, necessitating that the adhesive's "open time" (the interval between coating application and the completion of bonding) be precisely matched to this pace. It is essential to adjust the adhesive formulation and temperature to ensure that the adhesive achieves effective wetting and initial setting within 0.8 seconds, thereby preventing bonding failures caused by excessive line speeds.
Coating Thickness: Controlled within the 0.15 mm – 0.3 mm range.
Spiral spray or dot-pattern coating techniques are employed to ensure the adhesive layer is uniform and applied without excess. An overly thick layer can form hard lumps that compromise comfort, while an overly thin layer results in insufficient bonding strength. In actual production, a laser thickness gauge is frequently used for inline monitoring, maintaining a tolerance within ±0.02 mm.
Cooling Rate: Setting via Alternating Hot and Cold Processes.
Immediately following coating, the material enters an alternating hot and cold lamination process. High temperatures (approximately 80°C) are applied first to promote adhesive wetting, followed by rapid cooling to below ambient temperature (potentially as low as 15°C) to facilitate curing and setting. This process enhances the crystallinity of the adhesive layer, thereby boosting its holding power and creep resistance, and preventing displacement caused by elastic band retraction.
