US3389733A - Flexible container of plastic material - Google Patents

Description

June 1968 KARL-HEINZ SIEGEL 3,389,733

FLEXIBLE CONTAINER OF PLASTIC MATERIAL Filed June 6, 1966 FIG. 7

FIG. 2

2 Sheets-Sheet 1 June 25, 1968 KARL-HEINZ SIEGEL 3,389,733

FLEXIBLE CONTAINER OF PLASTIC MATERIAL 2 Sheets-Sheet 2 iled June 6, 196

United States Patent "ice 3,389,733 FLEXIBLE CONTAINER 0F PLASTIC MATERIAL Kari-Heinz Siege], Schwaig via Narnberg, Germany, as-

signor to ASF Gleitverschulss G.rn.b.H., Nnrnberg, Germany Filed June 6, 1966, Ser. No. 555,378 Ciaims priority, application Germany, July 7, 1965, S 98,059 3 Claims. (Cl. 150-3) ABSTRACT OF THE DISCLOSURE A closure for a bag of plastic material of the type comprising complementary profiled strips longitudinally provided within the bag opening and which can be closed with one another by pressure and which can be opened at the opening of the bag by pulling apart the walls thereof. The improved closure comprises one strip having a cross section including only one book facing the interior of the bag. The complementary strip is secured to the other wall of the bag and includes a double strip comprising a first strip portion having a flat surface resting against the back of the hook when the strips are closed together and a second strip portion provided with a hook profile which is complementary to and engages when closed the hook of the first-mentioned strip.

This invention relates to a flexible wrapper of plastics material, which consists preferably of a tube section which has been obtained by forming transverse heat-sealed seams in a tubing of thermoplastic material, which tubing has on the inside two longitudinally extending, profiled strips, which can be hooked into each other under pressure. Such wrappers of plastics material should be capable of being opened when required and to be closed in a simple manner when the contents or part thereof has been removed. Thus, it is an object to provide durable and reusable wrappers.

A known bag has walls consisting of plastics material sheeting and is provided near its edge between the mutually opposite inside surfaces of its walls with fastener elements, which can be caused to interengage and embrace each other. The dimensions and/or shapes of said elements are selected so that the resistance to their separation by an internal pressure of the bag is a multiple of the force which is required for their interengagcment or for their separation by an action which is exerted from the outside on the edge-s of the walls. This definition of the bag described in a prior publication contains only a detailed statement of the problem but does not disclose a solution to a person skilled in the art. When the subject matter of the prior publication is ascertained from the contents of the description, it is apparent that a solution of the problem set forth resides in that the head of a rib constitutes an unsymmetrical, enlarged portion, which on both sides of the root forms surfaces for a hooklike engagement with the associated edges of a groove, and that one of these surfaces, which is on the inside of the rib, has a higher inclination relative to the wall of the bag than the surface on the outside of the rib.

The present invention is based on the experience, which 3,389,733 Patented June 25, 1968 has been obtained in practice and by tests, that the known hooking elements of the flexible wrapper of plastics material described initially hereinbefore are suflicient to afford the desired resistance to a force which is produced by an internal pressure.

In view of this prior art, it is an object of the inven tion to provide a wrapper which consists of plastics material and which has hooking elements having enlarged interengaging surfaces and in which a resistance of hooking elements need not be overcome to open the package.

In a flexible wrapper of plastics material of the kind set forth initially hereinbefore, this object is accomplished by the invention in that one profiled strip consists of a unilateral hook, which is directed towards the inner part of the bag, and the other profiled strip comprises two flanges, which extend at right angles from the inside surface of the wrapper and are disposed on opposite sides of the hook of the opposite profiled strip, that flange which is disposed on the outside of the fastener being arranged to engage the back of the "hook, and that flange which is disposed on the inside of the fastener comprising a unilateral hook tip, which has a concave or re-entrant inside surface. The partial object of the invention to provide a wrapper which consists of plastics material and has hooking elements having enlarged interengaging surfaces is accomplished in that that flange of the one profiled strip which is disposed on the inside of the fastener consists of a unilateral tip having a concave inside surface hook. This results in a larger space between the two flanges which are to be interengaged. For this reason, the tips of the hooks may have a length which is sufficient to ensure a reliable closure. The further partial object of the invention to enable an opening of the wrapper without need for overcoming a resistance which is generated because two flexible hooking elements must be disengaged by bending, when they rub on each other, is accomplished in that the flange disposed on the outside of the fastener does not form a hook and the intermediate flange disposed on the opposite inside surface of the wrapper has no hook tip on the outside of the fastener. This profiled configuration takes account of the fact that any user of a wrapper of flexible plastics material in opening the same unconsciously performs with its hands a rotational movement about the longitudinal axes of the two profiled strips which have been hooked together so that the two unilateral hook elements are disengaged without need for a continually repeated expansion of the female part. A forcible separation of the two interengaged hook elements is unconsciously avoided. For this reason, the fastener according to the invention is less subjected to wear and for this reason has a longer life. Another advantage of the wrapper according to the invention resides in that a reliable fastener is obtained, which has only two hook elements whereas four hook elements were required in the prior art. Thus, it has been recognized that a hooklike enlargement at the flange end is required only on the inside of the fastener. Compared to the use of hooks in the form of arrowheads, this results in a saving of material and in a reduced space requirement for the enlarged portions. In flexible wrappers these aspects are of great practical importance because the endless tubing is divided on automatic bag-making machines by a fusion cutting and sealing operation into individual wrappers.

This results in difficulties when excessively thick profiled strips are used. These advantages become also apparent when the tubing of plastics material provided with profiled strips is supplied to a customer before it has been processed into individual wrappers. For such supply, the tubing is wound up in rolls. These rolls will now require a smaller space and have a lower weight.

In a particularly preferred embodiment of the invention, each of the interengaging surfaces of the two hooklike flanges includes an acute angle with the associated inside surface of the wrapper. This will ensure a particularly good closure in spite of the action of forces which might arise in the interior of the wrapper and tend to open the fastener. In view of the design of the profiled strips according to the invention, the fastener elements will not unduly resist an opening of the fastener from the outside.

In a further embodiment of the invention, the female profiled strip has a smooth back. This affords the advantage that the two profiled strips can be more easily interengaged than in known wrappers where the female profiled strip is tiltable relative to the inside wall of the wrapper.

An embodiment of the invention will now be described by way of example with reference to the accompanying drawing, in which FIG. 1 is a sectional view showing a cut-off portion of a wrapper according to the invention with the two profiled strips interengaged.

FIG. 2 is a diagrammatic view showing the die which is employed in the manufacture of the wrapper according to the invention.

FIG. 3 is a diagrammatic showing of the unconscious rotational movement which is performed by the hands about the longitudinal axes of the profiled strips when the wrapper is being opened from the outside.

FIG. 4 is a perspective view showing a broken-off portion of a seamless tubing, which has two profiled strips and is used in the manufacture of a wrapper according to the invention.

FIG. 5 shows a finished wrapper, which has been obtained by a fusion cutting and sealing operation from a tubing as shown in FIG. 4.

To enable a sale of the wrapper 1 according to the invention at a most attractive price, the wrapper is usually made from a seamless tubing 2 of plastics material. This tubing is provided with the profiled strips 3, 4 while it is being extruded and/or blown. Instead of a tubing of plastics material, plastics material sheeting may be used as a starting material. The provision of the profiled strips during the manufacture of the tubing is recited only as a preferred feature in the claims so that they constitute a bar to an unauthorized working of the invention by a third party, who might separately make the fasteners according to the invention and join them to the wrapper, e.g., by adhering, heat-sealing or stitching. Whereas this would result in a more expensive wrapper, it is known that an unauthorized user will usually accept this disadvantage if it enables him to avoid a protective right. He will be in a position to bear the higher expenditure because he does not have to spend money on research.

The profiled strips 3, 4 are provided on the inside surface 5 of the tubing 2 and extend longitudinally and can be hooked together by an application of pressure, as is apparent from FIG. 5.

One profiled strip 3 consists of a unilateral hook '7, which is directed towards the interior 6 of the bag. The other profiled strip 4 comprises two flanges 8, 9, which extend at right angles from the inside surface 5 of the wrapper 1 and are disposed on opposite sides of the hook 7 of the opposite profiled strip 3. The flange 8 disposed on the outside of the fastener in the outer part of the wrapper engages the back 26 of the hook 7. The flange 9 which is disposed on the inside of the fastener in the inner part 6 of the wrapper 1 comprises a unilateral hook tip 11 having a concave or re-entrant inside surface.

As is apparent from FIG. 1, the female profiled strip 4 has a smooth back 12. The interengaging surfaces 13, 14 of the two hook- shaped flanges 8, 7 include an acute angle on or [3, respectively, with the associated inside sur faces of the wrapper 1.

To provide a smooth back for the female profiled strip the die 15 may be designed as shown in FIG. 2. An extrusion slot 18, from which the tubing 2 emerges, is defined between the die bushing 16 and the die insert 17. In the die insert 17, the slot 19 for the flange 8 and the slot 20 for the unilateral hook tip 11 having a concave or re-entrant inside surface include an acuate angle The action of the air stream which prevents a collapsing of the tubing 2 emerging from the extrusion slot 18 holds the flanges 8 and 9 spaced apart by a distance which corresponds to the width of the smooth back 12.

If the wrapper according to the invention is not made from a flat sheeting but from an endless tubing 2, which has been integrally formed with the profiled strips in one operation, the tubing must be severed along line 21 in FIG. 5 so that two extensions 22, 23 are formed on the outside of the fastener. To open the wrapper according to the invention, the user instinctively grips the extensions 22, 23 so that the first two joints of each of its two forefingers are parallel to the two profiled strips 3, 4, as is apparent from FIG. 3, and the two thumbs have entered the gap which has been formed by slitting the tubing. Now each of the extensions 22 and 23 is held between a thumb and forefinger of one hand. To open the fastener, the two extensions 22, 23 are moved apart. In this operation, the two hands instinctively perform a rotation about the longitudinal axes of the fastener strips 3, 4.

The wrapper is closed in the manner which is conventional with pressure fasteners.

The side edges of the individual wrapper shown in FIG. 5 are constituted by transverse heat-sealed seams 24, 25 formed in a tubing 2 as shown in FIG. 4 on an automatic bag-making machine.

What is claimed is:

1. A reclosable flexible container comprising, a bag body having flexible walls formed of a plastic film with an upwardly facing opening, releasably interlocking rib and groove elements integrally part of the walls on facing inner surfaces thereof formed of a resilient material and separable by applying a force directly to the walls drawing the elements apart and interlockable by pressing the elements together, and external flange means on the upper exposed edges of said walls which may be gripped and drawn apart to separate said elements, said rib element being L-shaped in cross section and defining a first downwardly depending unilateral hook projecting at right angles from the interior of the wall with which it is integrally formed toward the opposite wall of the bag body terminating in a flat face which seats against a portion of the opposite interior wall surface, said groove element comprised of two flanges projecting at right angles from the interior of the wall with which they are integrally formed, said flanges being spaced apart a distance corresponding with said portion of the opposite interior wall surface, one flange being in the form of a fiat bar and seating against the back of said first hook, the other flange defining a second upwardly extending unilateral hook facing and mating with said first unilateral hook along their inside surfaces.

2. A reclosable flexible container according to claim 1 wherein the inside mating surfaces of said hooks form acute angles with the interior wall surfaces of the bag body.

3. A reclosable flexible container according to claim 1 wherein the inside mating surfaces of said hooks define facing concave surfaces.

(References on following page) Svec et a1.

Svec et a1. Ausuit Freedman.

6 FOREIGN PATENTS 567,093 3/1958 Belgium. 965,258 7/1964 Great Britain. 1,132,628 11/1956 France.

DONALD F. NORTON, Primary Examiner.

Examiners.

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