The testing process for hot melt adhesives used in sanitary napkins is a systematic and multi-dimensional quality control process, covering key aspects such as temperature performance, adhesive strength, application performance, and environmental hygiene.
Melt Viscosity Test: Measured using a rotational viscometer at 180℃, unit is mPa·s (or cPs). The standard requirement range is typically 6500~7500 cPs; too high a range affects coating smoothness, while too low a range leads to dripping.
Softening Point Test (Ring and Ball Method): Using the GB/T 15332 standard method, the temperature at which the hot melt adhesive begins to soften is tested. Generally, it is required to be within 82℃±5℃ to ensure that it does not deform due to high temperatures during storage and transportation.
Thermal Stability Test: The adhesive is continuously kept at a high temperature (e.g., 180℃) for several hours, and the occurrence of oxidation, discoloration, skinning, etc., is observed to evaluate its stability during prolonged heating on the production line.
180° Peel Strength Test: Performed according to GB/T 2792 or ASTM D3330 standards: Apply hot melt adhesive to a standard substrate (such as polyester film), adhere it to a standard jersey fabric, cure it, and then peel it off at a constant speed at a 180° angle. Record the average peel force.
Sanitary napkin adhesive standards require a peel strength between 100 and 800 mN (approximately 0.1 to 0.8 N/inch). Too low a strength may cause displacement, while too high a strength may damage clothing or cause discomfort.
Holding Power Test: Evaluates the adhesive's resistance to creep under continuous load to prevent slippage during use.