| abstract |
ABSTRACT A method of and apparatus for dynamically mechanically bonding together a plurality of laminae, at least one of which comprises thermoplastic material: for example, polyethylene. In one aspect of the invention the laminae are forwarded in face to face relation through a pressure biased nip between a patterned nip defining member and an opposing nip defining member (eg, a relief patterned cylinder and an anvil cylinder) which members are independently driven to maintain a predetermined surface velocity differential between them. In another aspect of the invention which is particularly useful at intermediate and higher line velocities --preferably for line velocities of about 300 feet or more per minute and, more preferably, for line speeds of about 450 feed or more per minute -- the nip defining members may be operated with equal surface velocities. In each of these aspects of the invention, the members may be biased towards each other to provide a predetermined pattern-element-psi loading; and, additionally, they may be independently heated to provide each with an elevated surface temperature which is, preferably, in a predetermined range below the melt temperature of the thermoplastic laminae disposed closest to or in contact with each respective nip defining member as the laminae are forwarded through the nip. |