Slider-operated fastener with spaced notches and associated preseals

Abstract

A slider-operated fastener comprises first and second opposing tracks including respective first and second interlocking profiles and respective first and second fins extending downward from the respective first and second profiles. The first and second fins are sealed to each other by a plurality of spaced preseals. After generating each preseal, a notch is formed in the profiles and upper portions of the fins at the generated preseal. To install a slider onto the fastener, the slider is initially positioned within the respective notch and then threaded onto the fastener in response to relative movement of the slider and the fastener. Either before or after the steps of forming each preseal and respective notch and installing the respective slider, the fastener is attached to a moving web of plastic film. The fastener-carrying web is later folded and sealed to form individual plastic bags. The preseals are advantageous in that they allow the fastener to be controlled during such downstream operations as notch formation and slider installation and when the fastener is tensioned by various rollers in the bag making machine. The preseals keep the interlocked profiles together and prevent them from moving longitudinally relative to each other. In addition, the preseals generally encompass the respective notches to assist in providing a leakproof barrier to entry into an interior of the fastener between the fins via the notches. This leakproof barrier is effective in the ultimately formed plastic bags.