Multilayer Film Welding with Embossed Interlocking Seams

The invention transitions from a conventional flat heat-sealing process to a three-dimensional interlocking connection. The welding device with protruding elements creates a mechanical interlock where film layers are physically interconnected in multiple dimensions, not just bonded at a single planar interface. This dimensional change significantly enhances both mechanical stability and load-bearing capacity.

The invention creates a composite weld structure combining thermoplastic resin material (from the coating layer) with the cellulose-based film layers. The protruding elements of the welding device embed into the thermoplastic material, creating a composite connection that leverages both the adhesive properties of the thermoplastic and the mechanical interlocking geometry, resulting in superior strength and reliability.

The welding device is segmented into multiple protruding elements rather than using a single large heating element. Each protruding element independently creates a localized weld point, collectively achieving large surface area engagement. This segmentation allows the device to maintain relatively simple construction while effectively increasing the connection surface area through multiple discrete contact points.

Instead of uniformly heating a large area with a complex device, the invention applies heat and pressure locally through multiple protruding elements. Each element concentrates energy at its tip to create a strong localized bond, and the collective effect of multiple such local bonds achieves the desired overall bond strength without requiring device complexity.