Loose leaf book binder spine and clip system

摘要

Stiff boards with various combinations of flexible and semi stiff plastic sheeting covering them are hinged to a curved spine of similar materials, by seam welds. The hinges coincide with the seam welds holding a flat inner spine in place to which the rings, clips or other bonding devices are riveted or other wise secured. The curved back hides these rivets from view. The hinge welds between the curved false spine and the covers may be replaced by using continuous lengths of the weldable materials to cover both the boards and the false spine. The flexible material is typically PVC and the semi stiff material is PVC with a low plasticiser content.