Patch handle bottom valve bag

Abstract

A patch handle bottom valve bag is formed from a tubular length of plastics material and is provided with a reinforcing patch, of a width less than 50% the width of the bag, adjacent the upper edge of the bag. The patch is heat sealed to one panel of the bag by a pair of linear heat seals and a handle opening is pieced through the patch and the underlying panels of the bag. The bag includes a heat seal which extends transversely of the bag, spaced from the upper edge thereof, this heat seal also extending across the patch adjacent the lower edge thereof. The bottom of the bag is formed in a conventional manner into a block bottom with a valve sleeve inserted and secured therein. The provision of the heat sealed reinforcing patch provides a stronger bag, one which uses less material, and one which will have fewer manufacturing problems when compared to existing reinforced bags.

Description

[0001] The present invention relates in general to bottom valve bags for transporting or carrying bulk material and in particular to such a bag having a reinforced handle portion.

BACKGROUND OF THE INVENTION

[0002] Plastic bags for carrying or transporting bulk material, including particulates, powders and the like are well known in the art. Such bags typically are provided with a bottom fill valve and a closed upper end. The material is injected into the bag through the fill valve when the bag is in an inverted condition, the weight of the material closing the valve when the bag is reoriented with its upper end elevated relative to its bottom end. The bag must be cut open to release the contents.

[0003] Such bags typically will have a handle at the top or upper end for carrying the filled bag. The handle might be a simple oblong hole cut through the bag material at the upper end; it might be formed from a separate piece of plastic or other material adhered or otherwise attached to the bag; or, as is illustrated in U.S. Pat. No. 4,610,029 of Sep. 2, 1986 it might involve a reinforcing patch adhered to the upper end of the bag with a handle opening piercing the patch and the underlying bag material.

[0004] While the reinforcing patch concept of the aforementioned US patent can be effective in creating a strong handle, the concept is somewhat wasteful of material and requires the use of an adhesive for securing the patch to the bag material. In the US patent strength is achieved by folding part of the upper bag end over on itself prior to adhering the patch to the bag. The patch extends across most if not all of the width of the bag and extends over and below the transverse heat seal which defines the upper closure for the bag. The result is an upper reinforced bag section that will exhibit at least five layers of material, four from the bag material and one from the patch material. For additional strength the US patent suggests that another patch can be adhered to the opposite face of the upper end, creating a six layer section.

[0005] While adhesives will provide a strong bond for the patch, they are aromatic and may involve controlled substance catalysts, thereby creating an unhealthy environment for workers in a bag assembly plant.

SUMMARY OF THE INVENTION

[0006] The present invention on the other hand represents an improvement over the bag construction of the aforementioned US patent. The invention utilizes a small patch of plastic material which is heat sealed to the bag material in the center thereof adjacent the upper edge of the bag. By heat sealing the patch to the bag instead of using adhesive a stronger bond between the patch and the bag is achieved. Furthermore, it has been ascertained that, unlike the patch used in the above-identified US patent, it is not necessary to extend the patch the full width of the bag. In fact, a patch which is less than one-half the width of the bag will be more than adequate, with a lower limit being about 20% of the bag width. Also, the patch need not be much wider than the distance from the upper edge of the bag to the heat seal which extends completely across the bag material to establish the upper end of the fillable bag body. That heat seal will also extend across the patch adjacent the lower edge thereof. In comparison to the patch of the aforementioned US patent the present invention represents a considerable saving in patch material.

[0007] By using a heat seal to attach the patch to the bag material there is less likelihood of workers being adversely affected by the attachment process. With the prior art adhesively-attached patches there are aromatic solvents associated with the adhesive which can be damaging to the environment as well as to the health of the workers. As mentioned above, the heat seal attachment for the patch results in a stronger attachment than adhesive. Once the patch is heat sealed to the bag material a handle opening is cut through the patch and bag material layers, between upper and lower lines of heat sealing used to secure the patch to the bag material.

[0008] At the opposite end of the bag a flat bottom is formed and a fill sleeve is inserted in a conventional manner. The sleeve is used to fill the bag in an inverted state with bulk material to be carried in the bag.

[0009] The present invention also contemplates a fast, efficient production method, starting with a roll of tubular, plastic bag material which is fed into a forming machine in a flattened state. A patch for each bag is brought into contact with the bag material, centrally thereof, at a location adjacent to what will be the upper edge of the finished bag. The patch is heat sealed to the bag material while in contact with the bag material and, essentially simultaneously, the bag handle opening is cut through the layers of patch and bag material. At the next station the bag material is heat sealed along a line extending transversely of the bag material to define the upper limit of the bag body, this heat seal also extending across the patch adjacent the lower edge thereof. Essentially simultaneously, adjacent the opposite or upper edge of the patch the bag material is cut transversely thereof to define the upper edge of the finished bag. This process severs the bag from the roll of bag material and the severed blank or unfinished bag is then fed to a bottom forming station for completion. At the bottom forming station a flat or block bottom is created by folding the material to create appropriate flaps which in turn are adhered together. Before completion a valve sleeve is inserted between selected flaps and adhered in place. The valve sleeve provides access to the interior of the bag so that bulk material can be forced into the bag until it is full. Once the bag is full it is inverted so that the bag can sit on the flat bottom, with the handle at the top for convenient usage. The weight of the bulk material in the bag closes the valve sleeve and prevents any leakage of material from the bag. If desired a rectangular reinforcing patch of plastic material can be adhered to the bottom of the bag.

[0010] Broadly speaking therefore the present invention may be considered as providing a plastic bag for carrying bulk material comprising: a body portion defined by a length of tubular plastic material and exhibiting opposed rectilinear panels; a reinforcing patch of a plastic material, having a width less than one half the width of the material, heat sealed to one of the panels adjacent a transverse upper edge of the panels; a heat seal extending transversely of the panels to seal the panels together, the heat seal being spaced from the transverse upper edge of the panels and extending across the patch adjacent a lower edge thereof; a handle opening pierced through the patch and the panels underlying the patch; and a closed bottom portion including a filling valve therein.

[0011] The invention may also be considered as providing a method of forming a plastic bag having a reinforced handle area comprising the steps of: providing an indefinite length of tubular bag material in a flattened state on a roll for dispensing such material therefrom; feeding such material into forming apparatus from the roll and, within such apparatus: providing a plurality of patches of plastic material of a width less than one half the width of the length of material; for each bag to be formed, positioning one of the patches centrally of the width of the material; heat sealing the patch to the material; piercing the patch and underlying opposing panels of the length of tubular material along a line to define a handle opening; effecting a heat seal transverse to the length of material, and extending across the patch, to seal together the opposing panels of the material; simultaneously severing the material along a line of severance spaced from the transverse heat seal to create an unfinished bag section having an upper portion between the transverse heat seal and an upper edge created at the line of severance, a body portion below the transverse heat seal, and an open bottom portion at the end opposite the upper portion, the patch being located in the upper portion; and forming the open bottom portion into a closed bottom portion having a filling valve therein.

[0012] The present invention will now be described in greater detail and with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIG. 1 is a perspective view of a carrying bag in accordance with this invention.

[0014] FIG. 2 is a front view of the bag of this invention.

[0015] FIG. 3 is a partial perspective view of the bag bottom.

[0016] FIG. 4 is a schematic representation of the process for manufacturing the bag of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0017] FIGS. 1 and 2 illustrate an industrial carrying bag 10 for bulk material in accordance with this invention. The bag is generally rectilinear in overall configuration and is typically made from a plastics material such as low density polyethylene (LDPE), linear low density polyethylene (LLDPE) or high density polyethylene (HDPE) which will not be degraded by the material being carried in the bag. The bag 10 has an upper transverse edge 12 which is open, defined by opposing panels 14, 16 of the bag material which are joined along side edges 18, 18. A transverse heat seal 20 extends the width of the bag material close to the upper edge, defining an upper portion 22 between itself and the upper edge 12. Below the heat seal 20 is the main body portion 24 of the bag, the main body portion terminating at a closed bottom portion 26. The closed bottom portion 26 is created from a plurality of flaps formed from the bag material as will hereinafter be described, and it is provided with a reinforcing patch 28 which covers most of the bottom surface. A valve sleeve 30 is fixed in the closed bottom to provide access to the interior of the bag for filling purposes as is conventional in the art.

[0018] The upper portion 22 of the bag is provided with a reinforcing patch 32 which is heat sealed to one of the bag panels 14, 16 along a pair of heat seal lines 34, 36 which are generally parallel to each other as well as to the upper edge 12 and the transverse heat seal 20. The patch is formed from a material compatible with the bag material, either an LDPE, an LLDPE or an HDPE and has a width of between about 20% and 50% of that of the bag itself. The height of the patch is about the same as that of the upper portion 22, with the uppermost edge of the patch being closely adjacent the upper edge 12 of the bag. The lower edge of the patch extends below the transverse heat seal 20. The patch 32 is heat sealed to the bag material before the transverse heat seal 20 is effected so that the heat seal 20 can actually extend across the patch 32 to provide an additional securement of the patch to the bag. A flattened C-shape line 38 is pierced through the patch and the underlying bag material to create a handle opening which will be used for carrying the filled bag.

[0019] As seen in FIGS. 1 to 3 the bag bottom 26 is formed from the bag material, generally as described below, such that a flat bottom surface 40 is created, the surface 40 having a generally rectangular central section 42 and triangular end sections 44, 46. One of the end sections 46 is completely sealed whereas the other end section 44 is not. The unsealed end section 44 is provided with the valve sleeve 30 which extends from the outside of the bag to the interior and is used for filling the bag with the material to be carried thereby. The sleeve is also made from a plastics material that is durable and flexible. The bag will be filled in an inverted orientation, with the sleeve uppermost. Once it has been filled the bag is flipped end to end so that the flat bottom is lowermost and the bag can rest on its bottom. In this orientation the weight of the material in the bag will maintain the valve sleeve in a compressed, closed condition so that there will be no leakage from the filled bag.

[0020] The manufacturing process in accordance with this invention is illustrated schematically in FIG. 4. The process starts with the provision of the raw material from which the bag will be formed, generally in the form of a roll 50 of tubular plastic material which is in a flattened state, defining the opposing panels or bag sides 14, 16.

[0021] The material is drawn from the roll 50 through a set of dancing rollers 52 to maintain tension in the material into the forming apparatus generally indicated by reference number 54.

[0022] At the first station in the apparatus a plurality of rectangular plastic patches 32 are provided, one for each bag to be made. A patch 32 is brought into contact with one panel of the bag material, centrally of the width thereof and at contact the patch is heat sealed to the panel using heat sealers 54, 56 along the spaced-apart heat seal lines 34, 36 which are parallel to each other and generally normal to the bag edges 18, 18. Also concurrently with the heat sealing of the patch to the bag material a flattened C-shaped cut 38 is pierced through the patch 32 and the bag material using die cutter 58 so as to define the handle opening.

[0023] At the next station a heat seal 20 is applied transversely of the entire bag width, using heat sealer 60, the heat seal being positioned such that it extends across the patch 32 adjacent the lowermost edge thereof, below the lower one 34 of the patch heat seals. Concurrently with the application of the transverse heat seal 20 a knife 62 is actuated so that the bag section 64 is severed from the length of bag material along a line of severance 66 which is located above and closely adjacent to the uppermost edge of the patch 32, thereby creating the upper edge 12 of the bag.

[0024] The severed bag section 64 is fed to the final station in the forming apparatus whereat the closed bottom 26 is formed. At that station adhesive is applied to both sides of the bag one to two inches from the bottom end thereof. This end is then scored, folded, opened, and folded again to create flaps. This is done in a conventional manner using suction cups, duckbills and rollers. The score location is determined by the desired width of the closed bottom 26. Pressure rollers are used to maintain the creases, and to hold the flaps down. In this way the flaps are presented up, with adhesive, ready to receive the valve 30.

[0025] The sleeve 30 is preformed of LDPE/LLDPE/HDPE film tape and is placed on one end of the bag bottom flaps. Pressure rollers are used to tack it down to the adhesive already applied to the flaps. The flaps are then folded over to create the rectangular bottom end of the bag. The sleeve 30, as described above, provides access to the bag interior.

[0026] The bag bottom may be reinforced by a rectangular patch 28 of heavy gauge LDPE/LLDPE/HDPE adhered to the bottom of the bag after the forming thereof as described above. After application of the reinforcing patch 28 the bottom of the bag is passed though a set of pressure rollers which ensure good sealing of the adhesive to the flaps, sleeve and patch.

[0027] The resulting bag is strong, light in weight and uses less material than other plastic carrying bags that are available on the market for the transporting of bulk powder or particulate material, including that of U.S. Pat. No. 4,610,029.

[0028] While particular embodiments of the present invention have been described herein it is understood that modifications to the invention can be effected without departing from the true scope of the invention.

Claims

1. A method of forming a plastic bag having a reinforced handle area comprising the steps of:

providing an indefinite length of tubular bag material in a flattened state on a roll for dispensing such material therefrom;

feeding said material into forming apparatus from said roll and, within such apparatus:

providing a plurality of patches of plastic material of a width less than one half the width of said length of material;

for each bag to be formed, positioning one of said patches centrally of the width of said material;

heat sealing said patch to the material;

piercing said patch and underlying opposing panels of said length of tubular material along a line to define a handle opening;

effecting a heat seal transverse to said length of material, and extending across said patch, to seal together said opposing panels of said material;

simultaneously severing said material along a line of severance spaced from said transverse heat seal to create an unfinished bag section having an upper portion between said transverse heat seal and an upper edge created at said line of severance, a body portion below said transverse heat seal, and an open bottom portion at the end opposite said upper portion, said patch being located in said upper portion; and

forming said open bottom portion into a closed bottom portion having a filling valve therein

2. The method of claim 1, wherein said patch is heat sealed to said material by a pair of spaced apart elongated heat seals parallel to said transverse heat seal, said handle opening being created between said pair of heat seals.

3. The method of claim 2, wherein said closed bottom portion is formed by folding bottom panel portions, sealing such bottom panel portions together, and creating said filling valve in said folded and sealed bottom panel portions.

4. The method of claim 3 wherein said closed bottom portion is formed by applying adhesive to said panels close to the bottom edge of said body portion, scoring said panels, folding said panels to create a plurality of flaps, inserting a valve sleeve from one side edge of said body portion between adjacent ones of said flaps, and overlapping said flaps and said sleeve in contact with said adhesive to close and form said bottom portion, with said sleeve providing access to the interior of said bag as said filling valve.

5. The method of claim 4 wherein said sleeve is formed from low density polyethylene, linear low density polyethylene, or high density polyethylene.

6. The method of claim 1, wherein said material is formed from low density polyethylene or linear low density polyethylene, and said patch is formed from low density polyethylene, linear low density polyethylene, or high density polyethylene.

7. The method of claim 4, including the step of adhering a reinforcing patch formed from low density polyethylene, linear low density polyethylene, or high density polyethylene to the exterior surface of said closed bottom portion.

8. The method of claim 7 wherein said sleeve is formed from low density polyethylene, linear low density polyethylene, or high density polyethylene.

9. A plastic bag for carrying bulk material comprising:

a body portion defined by a length of tubular plastic material and exhibiting opposed rectilinear panels;

a reinforcing patch of a plastic material, having a width less than one half the width of said material, heat sealed to one of said panels between adjacent a transverse upper edge of said panels;

a heat seal extending transversely of said panels to seal said panels together, said heat seal being spaced from said transverse upper edge of said panels and extending across said patch adjacent a lower edge thereof;

a handle opening pierced through said patch and the panels underlying said patch; and

a closed bottom portion including a filling valve therein.

10. The bag of claim 9 wherein said patch is heat sealed to said one panel by a pair of elongated spaced apart heat seals parallel to said transverse heat seal, said handle opening being located between said pair of heat seals.

11. The bag of claim 9, wherein said material is formed from low density polyethylene or linear low density polyethylene, and said patch is formed from low density polyethylene, linear low density polyethylene, or high density polyethylene.

12. The bag of claim 9, wherein said closed bottom portion includes a plurality of folded flaps adhered to each other with a sleeve inserted between opposing flaps to provide access to the interior of said bag as said filling valve.

13. The bag of claim 12, including a reinforcing patch of plastic material adhered to the exterior surface of said bottom portion.

14. The bag of claim 13, wherein said reinforcing patch is formed from low density polyethylene, linear low density polyethylene, or high density polyethylene.