A leakproof plastic zipper with integrated end stops for a zipper slider particularly suited for thermoplastic bags. An increased flange height above the interlocking elements of the zipper and an increased plow depth on the separator of the slider extending down between the flanges provide a means of stopping the travel of the slider past the ends of the zipper.
The separator structure depending from the slider has a configuration in vertical cross-section corresponding to an inverted T, the horizontal portion of the T having the ends thereof adapted to be received in window structure in the flanges above the interlocking elements and adjacent one of the integrated end stops.
The present invention relates to improvements in plastic reclosable fasteners or zippers with sliders for opening and closing the zippers on plastic-film bags and the like and particularly to a provision of a leakproof plastic zipper with integrated end stops for the zipper slider at the ends of the plastic zipper to seal the ends of the zipper and to provide stops to retain the slider on the zipper.
Plastic reclosable fasteners or zippers with sliders are well known in the art. The plastic zippers include a pair of male and female fastener elements in the form of reclosable interlocking rib and groove profile elements for cooperation with the slider for opening and closing the rib and groove elements. In the manufacture of plastic-film bags, a pair of these male and female profile elements extend along the mouth of the bag and are secured in any suitable manner to the flexible walls of the plastic-film bag. These zipper elements may be integral marginal portions of such walls or they may be extruded separately and thereafter attached to the walls along the mouth of the bag.
It would be desirable to provide a leakproof plastic zipper with integrated end stops for the zipper slider wherein the volume of material available at the ends of the rib and groove elements is not only adequate for forming integrated end stops without the need for end clamp members but is also adequate to include window structure for receiving the separator finger on the slider thus allowing the interlocking elements to close completely beneath the slider and create a leakproof seal. It would also be desirable to have the window create a "detent" effect in the closed position to maintain the slider in the closed position.
The zipper comprises a pair of flexible plastic strips having separable fastener means extending along the length thereof comprising reclosable interlocking rib and groove profile elements on the respective strips. The strips each include profiled flange structure extending along the length thereof parallel to the rib and groove elements. A straddling slider is positioned on the strips for closing or opening the reclosable rib and groove elements comprising an inverted U-shaped plastic member having a back for moving along the top edges of the strips with depending sidewalls projecting therefrom for maintaining the flange structure and the rib and groove elements therebetween. The slider includes separator structure depending from the back and inserted between the flange structure to open the rib and groove elements.
The sidewalls of the slider extend from an opening end of the slider to a closing end with the sidewalls being spaced wider apart at the opening end to permit separation of the rib and groove elements and being spaced sufficiently close together at the closing end to press the rib and groove elements into interlocking relationship as the slider is moved in a zipper closing direction. The flange structure and the rib and groove elements are vertically sealed together at both ends of the pair of strips to maintain the zipper closed at the ends and to provide integrated end stops for the zipper slider.
Window structure is provided in the flange structure beneath the top thereof and above the rib and groove elements and adjacent one of the end stops. The window structure is dimensioned to receive the separator structure at the opening end of the slider whereby when the slider is moved in the zipper closing direction, the interlocking rib and groove elements are closed throughout the length of the strips by the closing end of the slider and the separator structure at the opening end of the slider is received in the window structure and thus is ineffective on the flange structure to maintain open the interlocking rib and groove elements thereby to prevent leakage through the zipper.
In one aspect of the invention the separator structure depending from the back of the slider has a configuration in vertical cross-section corresponding to an inverted T, the horizontal portion of the T having the ends thereof adapted to be received in the window structure. In accordance with a further aspect of the invention, the horizontal portion of T is shaped to aid in release of the T shaped portion of the slider from the window structure when the slider is moved in the zipper opening direction.
While a preferred embodiment of the zipper invention has been described and illustrated, it is to be understood that further modifications thereof may be made within the scope of the appended claims without departing from the spirit of the invention. |
