US3473589A - Plastic bag - Google Patents

Description

Oct. 21, 1969 w. 0. G6T2 3,473,589

PLASTIC BAG Filed Dec. 9. 1966 2 24a /2 m /4 22 26 v I "I! IIIIIIIIIIIIIIIIIl/n 'IIIIIIIIIIIIII/IIIIIIIII' -,II,

22 Z4 Z0 32 /6 (30 A8 F1 g: 2 22 26m 30 /4 ,flmfll III II II II II II II i ll I II n INVENTOR.

WALTER 0. G6T2 BY ATTORNEYS nite States Patent m 3,473,589 PLASTIC BAG Walter O. Gtitz, Nenstadt, Germany, assignor to Minigrip, Inc., Orangeburg, N.Y., a corporation of New York Filed Dec. 9, 1966, Ser. No. 607,346 Claims priority, applieEatioiggrmany, Dec. 11, 1965, 3 Int. Cl. A45c 13/10; B65d 1/00 US. Cl. 150-3 8 Claims ABSTRACT OF THE DISCLOSURE A closure structure for a container and a method of making the structure with the structure having a first thin inner layer of flexible plastic material with a first fastener element extending therealong being of one piece with the layer and a second thin inner layer of flexible plastic material facing the first layer and having a uniform second fastener element extending therealong formed of a resilient material and being of one piece with the second inner layer and shaped to be releasably interlocked with the first fastener, a first outer layer positioned over the outer surface of the first inner layer and laminated thereto, a second outer layer positioned over the outer surface of the second inner layer and laminated thereto with each of the inner layers providing a resilient support for the fastener elements and the outer layers providing a backin for the support.

BACKGROUND OF THE INVENTION The invention relates to a material having flexible pressure interlocking releasable fasteners or interlocking elements extending therealong for forming bags or similar articles for containing items such as perishable goods.

Heretofore bags with pressure fastenable releasable interlocking elements for closures have been formed in various ways with one arrangement forming the fastener strips and attaching them to the top edges of the bags. Additional developments have embodied forming the fastener elements to be of one piece with the material of the bag. A primary consideration in the formation of such material with a fastener element is the satisfactory operation of the fastener elements. This is of paramount importance inasmuch as fastener elements which do not interlock properly or which can easily become accidentally opened are of little use and are particularly disadvantageous for containers for materials such as food stuffs where air and dirt can contaminate the contents. In order to have a satisfactory fastener element, the interlocking portions of the element must be related to each other and to the backing material in such a way that they can readily be closed by applying pressure to the outer surfaces of the material and can readily be opened by pulling the elements apart such as by separating connected opening flanges. There are many considerations and factors which are not obvious from merely viewing a fastener structure which have a bearing on its effieiency and usefulness. The fastener structure must be such that a container, and particularly the supporting walls for the fastener elements can take loads such as are encountered when the bags are stacked or can take rolling and twisting such as occurs with handling without inadvertently opening. The fastener structure must be so related to the supporting wall that it can be intentionally drawn open when desired without tearing the parts and without making them incapable of reuse.

To make an improved flexible closure it is necessary to make the interlocking rib and groove elements stronger to resist inadvertent opening and be more airtight. This of course makes the elements harder to separate inten- 3,473,589 Patented Oct. 21, 1969 tionally, and also increases the stress between the supporting elements and the fiber walls on which they are carried. Because material having elastic properties must be used for the fastener elements the supporting walls normally have the disadvantages of the elasticity of the material. In the present invention adequate strength is obtained for the walls supporting the elements without necessitating increasing the wall thickness an undue amount; that is by using a backing lamination for the wall, particularly at the place of support, having the support properties desired.

It is an object of the present invention to provide an improved combined fastener and material therefor and method of making which makes possible the formation of an improved reopenable container.

More particularly an object of the invention is to provide an improved fastener and supporting material therefor that lends a superior support relationship between the interlocking element and the supporting wall of material which has improved faculties for opening the fastener, keeping the fastener closed, and permitting reopening and reclosing.

A feature of the invention is the provision of an interlocking element which is made of one piece with an inner layer of a wall of material and wherein an outer layer is laid over the inner layer and laminated thereto so that support is afforded for the fastener element directly by the inner layer and reinforcing by the outer layer and a carrying platform or support is provided for the inner layer by the outer layer so as to afford an overall coaction between the fastener and the two layers and the line of lamination therebetween.

Other objects, advantages and features will become more apparent with the teaching of the principles of the invention in connection with the disclosure of the preferred embodiments thereof in the specification, claims and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a sectional view taken through a layer of material constructed in accordance with the principles of the present invention;

FIGURE 2 is a sectional view taken through the top of a container formed of the material of FIGURE 1; and

FIGURE 3 is a sectional view through another form of construction of the invention.

DESCRIPTION OF THE PREFERRED As shown in FIGURE 1, a first thininner layer 10 of flexible plastic material is provided having afirst fastener element 12 extending therealong. Thefastener elements 12 and 14 are complementary shaped for pressure interlocking and for being released when drawn apart. They are shown with the interlockingelement 12 being a female element having projecting sides and theelement 14 being a male element to be gripped by theelement 12 when in the interlocked position as illustrated in FIGURE 2. The interlocking elements may take various forms and theelement 14 may be arrowhead shaped with theelement 12 having overhanging sides to grip behind the head of the arrow. In the type of interlocking fastener shown, it is essential that the lips or sides of theelement 12 be sufficently flexible to bend when theelement 14 is pressed into the groove formed between the sides and the immediate base of the elements is preferably of the same material as the elements, yet the overall support for the elements must not tear or permanently stretch when the elements are separated such as when a bag is intentionally opened. The support for the fastener elements therefore constitutes an important part of the function of the elements making them capable of remaining interlocked during normal usage in handling, permitting them to be rigidly interlocked when pressed together, and permitting them to be opened when' necessary.

On the opposite side of the inner layer is anouter layer 16 which is positioned over the outer surface of theinner layer 10 and laminated thereto. Theinner layer 10 may be a flexible plastic material such as polyethylene and the outer layer forms another layer of material which affords mounting or a carrying support for theinner layer 10 providing a superior functional relationship particularly at the location where thefastener elements 12 and 14 are carried. In some instances, theouter layer 16 may be formed of a material such as polypropylene or may be formed of a metallic foil. In addition to providing a support for the fastener elements, the outer layer combined with the inner layer forms a composite wall which is substantially impervious to the penetration of moisture. In the formation of a plastic layer such as theinner layer 10 small minute holes often occur which extend through the material. By laminating the second layer to the first, these holes will be closed and a superior wall material will be provided.

As to thefastener elements 12 and 14, the flanges of the elements if made long or thin will tend to tear if the elements provide too strong a lock. By providing the present combination of elements, theouter layer 16 provides extra strength to the inner layer location of the flanges so that a strong lock can be used for thefastener element 12 and a superior strength and a tighter fastener is achieved than if a single layer were used. Further the outer material can be a stronger material (better suited for strength or support than the inner layer) such as where the inner layer is polyethylene and the outer layer is polypropylene. This makes it unnecessary to use an unnecessarily thick material to obtain the necessary strength.

FIGURE 1 may be considered as presenting a single sheet or wall or as plural walls. Ifseparate sheets 30 and 32 are used to make a bag or container, these sheets are welded or seamed together at their base and edges. If desired, the wall or sheet shown can be made as a single unit such as by being extruded from a die in one pass or the single sheet can be extruded in tubular form with the tube being slit along its length to form the sheet.

The sheet orwall 32 has anupper flange portion 24a on one side with a body portion on the other side. Similarly thewall 30 has a flange portion 22a on one side of thefastener element 14 and the body portion on the other side. Theflange portions 22a and 24a have lines of weakenedtear resistance 26 and 28 respectively. This is illustrated in FIGURE 2 with theareas 22 and 24 above thetear lines 26 and 28 being joined together to form a removable tear strip.

For the purpose of the tear strip, theouter layers 18 and 20 can be arranged to extend only to the tear strip thus accommodating more easily separation of the tear strip and actually providing a stronger backing for the material below the tear strip to facilitate better tearing. Further, the completed bag as it appears after the tear srip (formed of theareas 22 and 24) is removed, has theouter layers 18 and 20 extending to its top edge with the upper edges of the outer layers shown at 18 and 20 to provide the grippable flanges to separate thefastener elements 12 and 14.

In the arrangement of FIGURE 3, the tear line of weakened resistance has been omitted and the edges at 34 are thinned so that the entire edges can be removed.

The upper edges as formed by theareas 22 and 24, or formed by theportions 34 can be joined by being passed through a heated Pressing means, or, if desired, if the entire unit is extruded longitudinally as a tube they can be formed in one piece initially.

While the resultant bag which is formed as shown in FIGURES 2 and 3 is air and moisture tight if theouter layer 16 extends over the entire area, it is possible that the top, at the location of thetear lines 26 and 28, and/ or any other areas that may require reinforcing can be coated with a sealing lacquer so that the required impermeability is absolutely assured.

When the separate sheets orwalls 30 and 32 (or the single wall if the material is manufactured in one piece! are formed, after the inner layer has been extruded, with thefastener elements 12 and 14 being of one piece therewith and extruded concurrently therewith in accordance with the present method, theouter layer 16 is then POSI- tioned over the outer surface of theinner layer 10. it IS then laminated to the inner layer by known methods such as by including a thin layer of cement or thermoplastic adhesive between the layers. Or, if desired, the outer layer can be positioned and heat applied in a relative manner so as to merely join the two layers to accomplish the lamination. This actually causes a lamination layer at the juncture between the inner andouter layers 10 and 16 and this juncture functions further to provide superior support for thefastener elements 12 and 14. As forces on the exterior of the bag or on the bag walls tend to bend the fastener elements, they will yield limitedly with the resilient support afforded by the resilient plasticinner layer 10. This support is backed by the line of juncture or lamination between theinner layer 10 and 16, and the outer layer provide a support of strength and protection for the inner layer at the place where it supports thefastener elements 12 and 14. By providing a laminated outer layer. preferably less elastic or stronger than the inner layers. the fastener elements can be integral or of one piece with the bag wall, can be made of material of good elastic properties as is necessary for the elements, and can be very strong with the bag wall havingadequate strength without excessive thickness. The forcefi/hich occur at the fastener elements as they are separated tend to be transmitted or absorbed by the laminated material and particularly the strong outer layer. Also as stresses occur and tend to stretch the inner layer of material, they will not create a breach or tear in the outer surface of the material. This makes possible a substantially stronger fastener structure than has heretofore been available.

Thus it will be seen that I have provided an improved fastener structure material which meets the objectives and advantages above set forth. The material provides a light weight strong structure. If a single layer of material were used, of suflicient weight to stand the stresses of a strong fastener the wall and the integral fastener elements can be formed in a single extrusion process but this creates uneven cooling and stresses in the inner layer. However, with the structure of the present invention the outer layer is not affected by unequal cooling and uneven stresses are not introduced due to stretching, during extruding, providing a material which has a strength superior to other material of the same thickness which has been formed in a single layer.

The drawings and specification present a detailed disclosure of the preferred embodiments of the invention, and it is to be understood that the invention is not limited to the specific forms disclosed, but covers all modifications. changes and alternative constructions and methods falling within the scope of the principles taught by the invention.

I claim as my invention:

1. In a closure structure for a container or the like, in combination,

a first thin inner layer of flexible plastic material having a uniform first fastener element extending therealong formed of a resilient material and being of one piece with said layer,

a second thin inner layer of flexible plastic material facing said first layer and having a uniform second fastener element extending therealong formed of a resilient material and being of one piece with said second layer and shaped to be releasably interlocked with the first fastener element,

a first outer layer positioned over the outer surface of the first inner layer and laminated thereto,

said first inner and outer layers providing a first substantially monolithic wall so that said first inner layer provides a support for the first fastener element and the first outer layer provides a backing for the support with said layers coacting and allowing a stronger lock with a thin film,

and a second outer layer positioned over the outer surface of the second inner layer and laminated thereto, said second inner and outer layers providing a second substantially monolithic wall so that said second inner layer provides a support for the second fastener element and the second outer layer provides a backing for the support allowing a stronger lock with a thin film, said outer layers laminated to the inner layer opposite fastener elements so as to reinforce the inner layers in the area of said fastener elements.

2. In a closure structure for a container or the like in accordance with claim 1 wherein the combination includes the outer layers having a yield strength greater than said inner layers.

3. In a closure structure for a container or the like in accordance with claim 1, wherein the combination includes said inner layers being of polyethylene and said outer layers being polypropylene.

4. In a closure structure for a container or the like in accordance with claim 1 wherein the combination includes the inner layers being formed of a resilient plastic and said outer layers being formed of a metallic foil.

5. In a closure structure for a container or the like in accordance with claim 1 wherein the combination includes,

first and second Walls being joined to each other below the fastener elements to form a container and extending above said first and second elements providing separating flanges which may be drawn away from each other for detaching said first and second elements and separating the walls to open the container.

6. In a closure structure for a container or the like in accordance with claim 5 wherein said flanges are joined at an upper location spaced above said elements and have a line of weakened tear resistance formed between said joined location and said fastener elements.

7. In a closure structure for a container or the like in accordance with claim 6 wherein said outer layers extend upwardly to terminate adjacent said line of weakened resistance and the area above said line contains only the inner layer for accommodating tearing of the line of weakened resistance and removal of the material of the inner layer above said line.

8. In a closure structure for a container or the like,

in combination,

a thin inner layer of flexible plastic material having a uniform straight fastener element extending therealong formed of a resilient material and being of one piece with the layer,

said fastener element spaced inwardly from one edge of the plastic material forming a flange portion and being spaced inwardly from the opposite edge forming a body portion,

and a thin outer layer of material positioned over the surface of the inner layer opposite the fastener element and laminated thereto,

said layers providing a substantially monolithic wall for combining with another Wall to form a container with said other wall having another fastener element shaped to releasably interlock with the first fastener element,

said outer layer laminated to the inner layer directly opposite said fastener element so as to reinforce the inner layer at the area of the fastener element.

References Cited UNITED STATES PATENTS 2,519,290 8/1950 Saltz -3 2,780,261 2/1957 Svec et a1 150-3 2,861,022 11/1958 Lundsager 229-35 X 2,916,197 12/1959 Detrie et al 150-3 X 3,132,742 5/1964 Shapiro et al. 229-54 X 3,122,297 2/1964 Sachs 150-1 X 3,136,468 6/1964 Keller 229-35 3,198,228 8/1965 Naito 150-3 DONALD F. NORTON, Primary Examiner U.S. Cl. X.R. 150-1; 22-9-55

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