Tacked film roll and method of making same

Abstract

A wound roll of filmstrip of the type having a photographic emulsion layer on one strip face and a raised stripe disposed along one edge of the opposite strip face is so formed as to produce temporary adhesion between the stripe of one convolution and the emulsion layer of an adjacent convolution. Such adhesion or tacking, restricts relative movement of the convolutions, thereby avoiding effective axial expansion of the roll and the resultant generation of undue frictional forces during advancement of the strip through a cartridge in which is is housed. Such tacking may be achieved by forming the strip into a roll and by so applying energy to a flat end face of the roll as to cause localized melting of the emulsion layer of one convolution at its interface with the raised stripe of an adjacent convolution, whereupon subsequent cooling and rehardening of the emulsion produces adhesion of the convolutions at such interface. In a preferred method of practicing such invention, a wound but untacked roll is supported at one end face by a wall of an unassembled cartridge body and is positioned beneath a movable heating platen. When the platen is placed in contact with the opposite end face of the roll, a desired quantum of heat may be transferred to the wound strip to produce the above-mentioned melting and the resultant tack.