IE41832B1 - Improvements in or relating to fluid-tight fastners - Google Patents

Description

This invention relates generally to resilient fluid tight fasteners for providing flexible closures having a variety of different uses for example on brief cases, pouches, and wrappers.

Heretofore, resilient fasteners of the type including a generally interlocking rib and groove structure, sometimes including a slide and referred to as slide fasteners, have generally been constructed with some looseness in the assembly. This type of prior art fastener is represented by that of U.S. Patent Specification No. 2,713,421 wherein clearance is provided over the crowns of the ribs to enable the fastener strips to engage more readily as well as to permit relative sliding movement longitudinally between the strips.

Fasteners as just described are not leak proof, so that where a fluid-tight closure is required some other type of closure would be required, although a resilient fastener might be more convenient and advantageous.

One manner of solving this problem appears from U.S. Patent Specification 3,440,696 which discloses the provision of a relatively soft sealing thermoplastic substance which is placed under compression during engagement of the rj.b and and groove elements. However, that solution complicates manufacture of the fastener, requiring the bringing together of materials of different durometer characteristics instead of making the fastener from a single material as is conventional practice.

Accordingly, there has been a long felt need for a fluid-tight fastener which will provide a vapor lock oxhermetic seal, but which can be manufactured according to conventional practices, which comprise extruding the parts from a suitable plastics material of uniform characteristics suitable for the intended purpose.

The present invention is concerned with the provision of a resilient fluid-tight fastener which may be used as a closure for pouches, containers, wrappers, and the like, for enclosing articles and substances that must be protected against atmospheric, water or other deteriorating conditions, or, on the other hand, must retain within the enclosure a fluid substance without any leakage hazard.

The invention accordingly provides a fluid-tight fastener comprising a pair of mutually engageabie flexible closure strips each having a web portion and a marginal portion, at least the marginal portions being formed from resilient material and being arranged for mutual interlocking, each of the marginal portions having at least one solid form-retaining longitudinally extending rib, each of the marginal portions having alongside the or each rib thereof a groove or grooves, the groove or each groove being generally complementary to a rib of the other marginal portion, the maximum width of each rib being greater than the disengaged maximum width of its associated groove so that the rib causes the associated groove to expand laterally when receiyed therein and a respective bridge area of the resilient material overlying a crown surface of a respective rib when engaged in the respective groove and each bridge area joining the opposite sides of the respective groove and' maintaining the disengaged maximum width of the groove in a smaller dimension than the width of the associated rib, in each case thd bridge area being stretched by the lateral expansion of the groove on insertion of the rib and reacting under tension to draw the groove sides tightly against the sides of the associated rib , whereby the rib is sealingly gripped in fluid-tight relation by and between the groove sides, the groove having a disengaged depth larger than the disengaged height of an associated rib whereby to permit the stretched bridge area to draw in toward the crown surface of the associated rib.

Preferably, each groove is provided with an undercut longitudinal tooth for releasable interlocking engagement with a complementary undercut longitudinal tooth on the associated rib.

The invention will be readily understood from the following illustrative description and accompanying drawings, in which: Fig.l is a fragmentary sectional isbrnetric view of an exemplary fluid-tight fastener embodying the invention,Pig.2 is an exploded assembly view of the fastener on a larger scale, showing complementary portions thereof separated, and schematically illustrating certain features contributing to the improved results attained with this fastener; Fig.3 is an enlarged sectional view of the fastener assembled together and schematically illustrating how the parts of the fastener, stretch when assembled to attain the desirable compressive sealing reaction therein; and Fig.4 is a transverse sectional view showing a modified form of fastener embodying the invention.

Xn Fig.l there is depicted a fluid-tight fastener 5 embodying the invention and comprising a pair of complementary flexible closure strips 7 and 8 each of which has a web portion 9 provided with a marginal portion 10. Although the web portions 9 and the marginal portions 10 may be constructed from different materials, but with at least the marginal portions 10 formed from strongly resilient material, in the construction shown both the web portions 9 and the marginal portions 10 are formed integrally in one piece as an extrusion made from a suitable durometer thermoplastic material. Relative flexing movement between tho portions 9 and lo of each of the strips is facilitated by the provision of a longitudinal, groove 11 between Ihe web portion 9 and the highly resilient marginal portion 10 in each instance.

For separable interlocking of the marginal portions 10 they are provided with respective, complementary longitudinal interlocking ribs 12 and grooves 13. Each of the marginal portions 10 is provided with at least one rib 12 and one groove 13, but in the preferred arrangement shown, each of the marginal portions has two ribs and corresponding grooves. Each of the ribs 12 has an undercut tooth 14 along one side complementary to and releasably in terlockingly interengageable with the like tooth of the rib 12 assembled therewith.

The construction and relationship of the interlocking ribs 12 and grooves 13 is such that in the assembled relationship the ribs 12 are sealingly gripped in fluidtight relation with the grooves 13. For this purpose, the ribs 12 are made wider than the disengaged width of the grooves 13 so that the ribs as received in the grooves cause the grooves to expand and areas of the marginal portions 10 at the grooves to stretch and react under tension to place the ribs 12 under compression. On reference to Pig.2, for example, it will be observed by comparing the full line and the dash-line representations of the strips 7 and 8 that the grooves in the disengaged condition of the marginal portions 10 are significantly narrower than the widths of the ribs 12. Therefore, when the ribs 12 are forced into the grooves 13 until the teeth 14 interlock, the sides of the grooves 13 must move apart to accommodate the inserted ribs 12. This causes areas of the marginal portions 10 at the grooves, and more particularly bridge areas 15 of the marginal portions 10 connecting the ribs 12 with one another and with the web portions 9 to stretch and elongate transversely, as indicated by the full line showing in Fig.3 as compared to the dash-line illustration therein. Because of the resilient characteristics of the material of the fastener, such stretching causes a corresponding reaction due to the tension generated tending to pull the sides defining the grooves 13 back toward their disengaged positions, resulting in placing the sides of the ribs 12 under compression between the sides defining the grooves, As a result, the side surfaces of the ribs 12 and of the grooves 13 are in tight gripping relation and effectively hermetically seal the fastener 5.

To facilitate the stretching and tensioning of the bridge areas 15, the relative shapes and relationship of root surfaces 17 of the grooves 13 and confronting crown surfaces 18 at the heads of the interlocking ribs 12 are Such as to leave freedom of relative movement therebetween during the assembly of the ribs into the grooves. To this end, the root surfaces 17, in the grooves 13, are arched away from the ultimate positions of the crown surfaces 18 and further, the crown surfaces 18 are relatively flattened so that a spaced relationship between the root surfaces and the crown surfaces persists after assembly has been completed, as is seen in Figs. 1 and 3.

It will be observed that while the crown surfaces 18 remain substantially in their original shapes the root surfaces 17 tend to flatten somewhat and pull in toward the crown surfaces 18 as the bridge areas 15 pull in toward said crown surfaces 18 by reason of the stretching of the bridge areas.

A reasonable degree of control upon the stretch characteristics of the material of the bridge areas of the interlocking marginal portions of the fastener may be effected by selection of the thicknesses of the bridge areas. For example, in the modified fastener of Fig.4 the bridge areas 15' shown in full line are substantially thinner than the bridge areas 15 indicated in dash-line and corresponding to the bridge areas in the fastener of Figs. 1 to 3. In other respects the fastener remains the same and therefore identical reference numerals indicate identical parts according to the foregoing description.

By making the bridge areas 15' thinner, an easier stretching is attained. Of course, by the same token, by increasing the thicknesses of the bridge areas in any instance increased resistance to stretching and a tighter leakproof grip on the interlocking ribs can be attained, though if the bridge areas are too thick, no stretching will be possible and the fastener will not close.

Fasteners embodying the invention may be arranged 10 to be opened and closed by means of any preferred form of slider. When closed, a thorough hermetic seal is provided against internal or external leakage of fluid F, shown for illustrative purposes in Fig.l as a liquid on one side only of the fastener. Fluid F may, of course, be on both sides of the fastener, where mixing or contamination of one fluid by another must be avoided as, for example where a sealed package containing fluid must be stored or transported in another fluid. Also, the fluid may be in a vapor, gaseous, or a liquid ph^se.

Claims (7)

1. CLAIMS:1. A fluid-tight fastener comprising, a pair of mutually engageable flexible closure strips each having a web portion and a marginal portion, at least the 5 marginal portions being formed from resilient material and being arranged for mutual interlocking, each of the marginal portions having at least one solid form-retaining longitudinally extending rib, each of the marginal portions having alongside the or each rib thereof a groove or grooves, 10 the groove or each groove being generally complementary to a rib of the other marginal portion, the maximum width of each rib being greater than the disengaged maximum width of its associated groove so that the rib causes the associated groove to expand laterally when received therein and a 15 respective bridge area of the resilient material overlying a crown surface of a respective rib when engaged itt the respective groove and each bridge area joining the opposite sides of the respective groove and maintaining the disengaged maximum width of the groove in a smaller 20 dimension than the width of the associated rib, in each case the bridge area being stretched by the lateral expansion of the groove on insertion of the rib and reacting under tension to draw the groove sides tightly against the sideS of the associated rib, whereby the rib is sealingly 25 gripped in fluid-tight relation by and between the groove sides, the groove having a disengaged depth larger than the disengaged height of the associated rib whereby to permit the stretched bridge area to draw in toward the crown surface of the associated rib. 30

2. A fastener as claimed in claim 1 in which the crown surface of each rib is flattened relative to the associated groove surface provided by a respective bridge area.

3. A fastener as claimed in claim 1 or claim 2 in which the stretching tension of each bridge area is controlled by 35 the thickness of the bridge area. A fastener as claimed in claim 3 in which the bridge

4. - 9 area is relatively thin so that the bridge area is stretched with only moderate tension.

5. A fastener as claimed in claim 3 in which the bridge area is relatively thick and the stretching thereof effects 5 a strong tensioned reaction for gripping the associated rib.

6. A fastener as claimed in any preceding claim in which each groove is provided with an undercut longitudinal tooth for releasable interlocking engagement with 10 a complementary undercut longitudinal tooth on the associated rib.

7. A fluid-tight fastener substantially as herein described with reference to Figs, 1 to 3 or Fig. 4 of the accompanying drawings.