Combined Closure And Handle For A Thermoplastic Bag And Method Of Producing Same

Abstract

A combined closure and handle for heavy-duty thermoplastic bags constituted by a continuous beaded strip having integral depending spaced skirts. The closure member is extruded from thermoplastic material and includes longitudinally extending and spaced depending skirts; the abutting front and rear wall mouth portions of the bag are received between said depending skirt and sealing is effected therethrough transversely of the bag and across the full width thereof. By punching or similar operation a hand-hold aperture is produced centrally of the bag within the confines of the sealed skirt portions of the closure member and through the enclosed front and rear wall portions of the bag. The present invention relates to heavy-duty thermosplastic bags and to a novel method for closing and sealing the open mouth thereof after the bag will have been filled.

Description

The present invention relates to heavy-duty thermoplastic bags of the character used in connection with the packaging and shipment of pulverant materials such as seeds, fertilizer, and the like. Bags of this character, particularly where the contents may weigh a substantial amount, generally are filled through a combined manual and automatic process insuring the proper delivery of each bag from a filling station to a sealing station.

Bags of the character with which we here are concerned require a handle of some sort for convenient handling and it has been known in the prior art to provide closure strips with handles attached thereto or to attach the handle as a separate operation to the filled and sealed bag.

Such assemblies are both costly and time consuming and there are obvious disadvantages in connection with projecting handles which require both careful alignment and space when the bags are stacked for shipment, storage, or the like. Accordingly, it is a major purpose of the present invention to provide a combined closure member and handle for thermoplastic bags which can be sealed to the bag with particular convenience and which will not increase the overall dimensions thereof.

We here are concerned with methods for the closing and sealing of one end of a thermoplastic bag, the other end being left open for filling and sealing by normal techniques, and with methods for closing and sealing one end of a bag; the other end having been formed previously to contain a valve, or alternately formed to contain a valve after the application of a handle.

It is a further object of the invention to provide a profile-extruded closure member in continuous strip form whereby portions thereof of appropriate length may be severed successively in an automatic sealing operation in accordance with the width of the thermoplastic bags to which each severed sealing closure is attached.

It is a still further object of the invention to provide a novel closure member for the sealing of the mouth of the thermoplastic bag and means for producing a hand-hold aperture centrally of said closure member and through the included bag side walls whereby an integral handle portion is produced.

Further objects and advantages of the invention will be readily apparent from the following discription, taken in connection with the accompanying drawings, wherein:

FIG. 1 is a perspective view illustrating, somewhat diagrammatically, mechanism for conveying filled bags progressively to a closure applying station, a closure sealing station, and a hand-hold producing station;

FIG. 2 is a transverse sectional view taken on the line 2--2 of FIG. 1;

FIG. 3 is a fragmentary perspective view of the upper extremity of a thermoplastic bag illustrating the novel closure member of the present invention sealed thereto and with the hand-hold aperture having been produced;

FIG. 4 is a vertical sectional view on an enlarged scale through the handle portion of the sealed bag taken on the line 4--4 of FIG. 3; and

FIG. 5 is an enlarged detailed sectional view taken on the line 5--5 of FIG. 3 illustrating the sealed relationship between the closure member and the wall portions of the bag mouth.

As shown in the drawings, thermoplastic bags 10 produced conventionally from tubular material sealed across the bottom 11 and including front and rear walls 12 and 13, respectively, are filled with the commodity 14 being packaged and then are advanced progressively to a closure or sealing station.

Suitable means may be utilized for the handling of these filled bags and, as shown in FIG. 1 of the drawings, an endless belt conveyor 15, suitably driven and passing over rollers 16, may be employed for such purposes. A pair of guide rails 17 and 18 may be provided and the filled bags conveniently travel therebetween. Desirably, the location of these guide rails is adjacent the open bag mouth so that the front and rear walls 12 and 13 of the bag will be maintained in substantially erect alignment.

The novel closure member 20 contemplated desirably is extruded from suitable thermoplastic material and includes a pair of spaced and depending skirt portions 21 and 22, a space 23 being provided therebetween for the convenient reception of the upper extremities of the adjacent front and rear walls 12 and 13 of the bag mouth. The upper longitudinal edge of the closure member or strip includes an enlarged bead portion 24 for increased strength and convenient handling and which, desirably, is hollow as indicated at 25 to minimize shrinkage in connection with the production thereof.

The thermoplastic bags of the character with which we presently are concerned are heavy-duty and the gauge thereof may be on the order of 5 mils or greater. Desirably, the gauge of the closure strip is on the order to 10 mils or greater and that of the depending skirt portions of the closure strip is on the order of 2.5 mils or greater and the space therebetween is sufficient to accommodate snugly the opposed front and rear walls of the bag mouth.

Following positioning of the strip 20 upon the bag mouth, the strip is severed by suitable mechanisms (not shown) to provide a detached length slightly in excess of the width of the bag so as to overlap, to a small extent, the bag side edges. The bag and overlying closure strip then are advanced to a sealing station where heated sealing means is employed to seal or weld the closure strip and contained bag wall mouth structure to each other. This seal, indicated at 26, is of substantial width and extends across the full width of the bag and closure strip and may be effected by heated rollers 27, or by flat sealing bars (not shown), as is well known in this and related arts. The degree of heat required and the dwell time with bar type sealers, or the rate of bag travel with sealing rollers, is dependent upon the nature and gauge of the thermoplastic material employed and appropriate control means is provided for the variance thereof in accordance with specific requirements.

Following completion of the sealing operation, the sealed and closed bag is advanced between the guide bars 17 and 18 to a hand-hold creating station where an aperture is produced through the sealing strip and enclosed bag walls, centrally of the width of the bag, immediately below the bead 24 and within the confines of the sealing strip.

Any suitable means may be employed for producing this hand-hold aperture and, as shown more particularly in FIGS. 1 and 2 of the drawings, a cutting bar 28 is mounted on one side of the bag with a guide block 29, having an aperture 30 therein complementary to the dimensions of the cutting bar 28, mounted on the opposite side of the filled and sealed bag. It will be obvious that reciprocal movement of the cutting blade 28 through the closure strip and sealed bag mouth and into the recess 30 in the guide block 29 will produce an aperture 31 located within the confines of the closure strip 20 and immediately beneath the bead portion 24 thereof.

It will be noted that the sealed area 26 extends beneath the bottom edge of the aperture 31 as indicated at 26a and this precludes any possibility of destruction of the seal extending across the full width of the bag mouth with possible inadvertent loss of contents.

Any suitable polymeric material such as polyethylene, polypropylene, and the like, or laminates of such materials, may be employed for the bag and the closure strip should be produced of a thermoplastic material compatible to that from which the bag is produced and readily heat-sealable therewith. Polyethylene has been found to be particularly suitable for present purposes and, where laminated material is employed, improved moisture barrier and related beneficial characteristics are readily available. Utilizing a polyethylene bag having a gauge approximating 5 mils and a 10 mil gauge for the closure strip, with a gauge on the order of 2.5 mils for the depending skirt portions, where rotary sealers are employed a sealing temperature on the order of 300.degree. F to 500.degree. F provides a thoroughly effective seal. With a 20-pound bag, the rate of forward movement may be on the order of 16 feet per second, with a 40-pound bag, a rate of travel of 25 feet per second may be utilized with equal efficiency. Where bar sealers are employed, a temperature on the order of 350.degree. F to 500.degree. F with a dwell time of 1 and 1/2 seconds has been found to provide a complete weld between the closure strip and the walls of the bag mouth. While closure strip dimensions may vary through a wide range in accordance with specific requirements as to bag size and weight of contents, it has been found that the following dimensions produce a particularly satisfactory end product:

Overall height of closure strip -- 1 1/4 inches

Diameter of bead -- 1/4 inch

Diameter of aperture in bead -- 1/16 inch

Height of skirts -- 3/4 inch

Width of seal -- 1/2 inch

Length of hand-hold aperture -- 3 1/2 inches

Height of hand-hold aperture -- 1 inch

It will be obvious that bags having heavily reinforced sealed mouth portions with conveniently accessible handles may be produced in accordance with the present inventive teachings with particular ease, insuring against inadvertent detachment of the carrying handle and/or rupture of the bag at the sealed mouth thereof.

The present invention is directed not only to the novel closure strip and sealed bag referred to hereabove, but also to the method of production thereof including steps of advancing a filled bag to sealing position with the wall portions of the open mouth supported in aligned relationship; positioning an extruded closure strip with depending skirt portions in embracing relationship with respect to the mouth of the bag; advancing the bag and closure strip to a sealing station; heat-sealing the skirt portions of the closure strip to the enclosed mouth portions of the bag front and rear walls; advancing the sealed bag to a hand-hold producing station and creating a longitudinally disposed hand-hold aperture in the bag centrally thereof, the upper edge of this aperture being in substantial alignment with the lower edge of the bead portion of the closure strip while the lower edge of the hand-hold aperture is located well within the sealed area.

The present inventive concept also contemplates modified arrangements whereby only one skirt portion of the sealing strip 20 will be sealed to the adjacent bag side wall. This will permit the production of a bag and integral handle as a commercial product which then may be filled and sealing of the remaining side wall may be accomplished thereafter.

It will be obvious to those skilled in this and related arts that various changes may be made in the invention without departing from the spirit and scope thereof. Therefore, the invention is not considered limited by that which is shown in the drawings and described in the specification and reference is had to the claims for summaries of the essentials of the invention, novel features of construction, novel combinations of parts, and method, for all of which protection is desired.

Claims

What is claimed is:

1. In combination, a thermoplastic bag-like container comprising front and rear walls united along the side and bottom edges thereof, the aligned free edges of said front and rear walls constituting an open mouth portion, and a combined closure and handle for said bag;

said combined closure and handle being constituted by an elongated strip produced from thermoplastic material, said strip having an enlarged longitudinally extending bead along the upper edge thereof and a pair of integral longitudinally extending spaced skirt portions depending from said bead and enclosing therebetween the aligned front and rear mouth wall portions of said thermoplastic bag, said closure strip extending across the complete width of said bag;

a heat sealed area extending completely across said closure strip and enclosed bag wall mouth portions, said heat sealed area being located beneath the bead portion and above the bottom edges of said skirt portions;

and a longitudinally extending hand-hold aperture produced within the confines of said closure strip and enclosed bag mouth wall portions, the top edge of said hand-hold aperture being in alignment with the bottom edge of the bead on said closure strip and the bottom edge of said aperture being located within the heat sealed area extending across said closure strip and enclosed bag mouth.

2. A sealed thermoplastic bag-like container as set forth in claim 1 where said closure strip is extruded from polymeric material and said bag is produced from a compatible polymeric material readily heat sealable therewith.

3. A sealed thermoplastic bag-like container as set forth in claim 2 where said polymeric material is polyethylene.

4. A sealed thermoplastic bag-like container as set forth in claim 1 where the longitudinally extending bead on said closure strip is hollow.

5. A thermoplastic bag-like container as set forth in claim 1 where said closure strip is sealed to only one of said enclosed bag wall mouth portions.

6. A combined closure and handle in combination with a thermoplastic bag having an open mouth portion, said combined closure and handle comprising an elongated strip produced from thermoplastic material, said strip having an enlarged longitudinally extending bead along the upper edge thereof and a pair of integral longitudinally extending spaced skirt portions depending from said bead, the open mouth portion of said thermoplastic bag being received between said spaced skirt portions, the height of said skirt portions being substantially greater than the diameter of said bead and a longitudinally disposed hand-hold aperture extending through said skirt portions within the confines thereof, said hand-hold aperture also extending through the open mouth portion of said thermoplastic bag received between said spaced skirt portion.

7. A combined closure and handle in combination with a thermoplastic bag as set forth in claim 6 where said longitudinally extending bead is hollow.