The structural adhesive used in diapers is typically a Hot Melt Pressure Sensitive Adhesive (HMPSA). This is a solvent-free, eco-friendly thermoplastic adhesive that exists as a solid at room temperature; upon heating, it melts and flows, and upon cooling, it rapidly solidifies to form a bond.
The primary material components of this adhesive are synthetic rubber-based polymers (such as SIS, EVA, etc.), supplemented with additives-including tackifying resins, plasticizers, and antioxidants-to achieve a balanced combination of rapid bonding, strong holding power, and good elasticity. It typically appears as light yellow or transparent solid blocks, operates at a working temperature of approximately 160°C, and complies with relevant standards such as GB/T.
In diapers, the structural adhesive serves as a "skeleton," used to bond various materials-such as the non-woven topsheet, absorbent core, PE backsheet, leak guards, and elastic bands-thereby ensuring that the overall structure remains secure, stable, and leak-proof. Given that the quantity used is minimal and the adhesive is encapsulated within multiple layers of material, the structural adhesive found in legitimate products has undergone and passed skin safety testing; it is non-toxic, odorless, and poses no harm to the human body.