EP1003678A1 - Flat bottomed plastic bag - Google Patents

Abstract

An expandable plastic film gusseted bag in which each front panel gusset (64, 66) is connected to a rear panel gusset and each of the panel gussets is foldable between the front panel (63) and the rear panel to provide a continuous bag periphery. A bottom joins the bottom of the front panel, rear panel, two rear panel gussets and two front panel gussets at substantial right angles to the side edges of the front panel, rear panel, and gussets to close the bottom of the bag and leave only the top (62) open. The improvement provides the plastic bag with eight first linear folding axes adjacent the bottom. A linear folding axis is located within the front panel, each front panel gusset, the rear panel, and each rear panel gussets. Each folding axis extends from the joinder of a gusset at the bottom to a side edge of the front panel or the rear panel and the front panel gusset or the rear panel gusset at an approximate 45° angle. The folding axes are made by a process restricted to a group consisting of a cold seal and a hinge in the plastic film while the film is planar. On opening of the expandable gusseted bag, the bottom seal of the bag disposed adjacent the gussets forms a generally triangular shaped overlay relative to the gussets to form a flat bottom bag.

Description

FLAT BOTTOMED PLASTIC BAG

This invention relates to plastic flat bottom bags. More particularly, a plastic flat bottom bag is illustrated where either a hinge, a cold seal, and/or a hybrid cold seal and hinge forms a linear folding axis for squaring out the bottom of the bag. This construction enables rapid bag manufacture of the resultant flat bottom bag making this design competitive for the first time with conventional plastic bags

CROSS-REFERENCES TO RELATED APPLICATIONS This application claims priority from Provisional Patent Application 60/088,613 filed June 9, 1998 by the named inventor herein entitled Plastic Film Hinging Patent Application Serial No. 09/257,345 filed February 25, 1999 of even date herewith entitled Plastic Film Hinging and Precreasing Process is likewise incorporated by reference as if fully set forth herein.

This application claims priority from Provisional Patent Application entitled Cold Sealing of Plastic Film 60/088,612 filed June 9, 1998. by the named inventor herein. Patent Application Serial No. 09/257,848 filed February 25, 1999 of even date herewith entitled Apparatus and Process for Cold Seal in Plastic Bags is likewise incorporated by reference as if fully set forth herein.

This application claims priority from Provisional Patent Application 60/089,582 filed June 17, 1998 by the named inventor herein entitled Plastic Bag Bundling System. Patent Application Serial No. 09/258,010 filed February 25, 1999 of even date herewith entitled Plastic Bag Bundling System is likewise incorporated by reference as if fully set forth herein.

This application claims priority from Provisional Patent Application 60/089,583 filed June 17, 1998 by the named inventor herein with Don Pansier of Greenbay Wisconsin entitled Automatic Ventilating System. Patent Application Serial No. 09/258,033 filed February 25, 1999 of even date herewith entitled Automatic Ventilating System is likewise incorporated by reference as if fully set forth herein. This application claims priority from Provisional Patent Application 60/092,232 filed July 9, 1998 entitled Plastic Bag Manufacturing Process by the named inventor herein. Patent Application Serial No. 09/257,843 filed February 25, 1999 of even date herewith entitled Plastic Bag Manufacturing Process is likewise incorporated by reference as if fully set forth herein.

Finally, this application claims priority from Provisional Patent Application 60/092,233 filed July 9, 1998 entitled Plastic Film Rigidity Means by the named inventor herein. Patent Application Serial No. 09/258,015 filed February 25, 1999 of even date herewith entitled Plastic Film Rigidity Means is likewise incorporated by reference as if fully set forth herein.

This Application also claims priority from U.S. Patent Application Serial No. 09/257,361 filed February 25, 1999 entitled Flat Bottom Plastic Bag.

The above Provisional Applications and all following Regular Patent Applications filed of even date herewith - and all of them - are herein incorporated by reference as if fully set forth herein.

BACKGROUND OF THE INVENTION

Flat bottom plastic bags are known.

In such flat bottom plastic bags, it is necessary to form a folding axes so that upon bag opening, the flat bottom of the bag hinges along diagonal fold lines to "square out" and form an upstanding bag structure for the receipt of articles to be placed in the bag. In addition to paper bags in commerce, exemplary of the prior art is:

Platz et al US Patent 3,917,159 takes an already manufactured bag and folds the bottom so that it will "square out."

Le Fleur et al US Patent 3,915,077 utilizes individual heat seals to form the "squared out" portion of the bag.

Hanson et al US Patent 3,988,970 discloses a bag process where a square bottom bag is first produced. Thereafter, the bag is folded so that the plastic film emulates the folding present in ordinary paper bags. This folding process occurs after the square bottom bag is fully manufactured. Ross et al relates to a plastic bag that utilizes among other constitutents glue. In the disclosure that follows, a plastic bag is manufactured which uses either "cold seals", hinges, and/or hybrid cold seals and hinges in plastic film for the rapid production and formation of a plastic bag. It is important that the reader understand both of the "cold seal" and "hinge" terms and how they are limited in the disclosure that follows.

First, it is important to understand that in modern plastic bag manufacturing technology, speed of film processing is essential. In a typical bag manufacturing process, film passes through a machine for bag manufacture at rates up to 300 feet per minute is required for economic manufacture. Further, each manufacturing step must anticipate the subsequent opening and loading of the bag. As a consequence, steps taking an inordinate amount of time slow down the bag line speed and are generally unacceptable. Further, any bag post-production step - such as folding an already manufactured bag - is unacceptable.

Because of this speed requirement, so-called "hot seals" are generally not acceptable for any portion of the bag that does not require full strength sealing. In a hot seal, one film layer of a bag is permanently fused to another film layer of a bag. Hot seals take time to produce. Melting must be sufficient for complete fusing to take place between the bag parts. As a result, a hot seal is a significantly slower method of plastic bag manufacture than either utilizing a "cold seal" or forming a "hinge" within plastic film.

In a hot seal application transverse to the direction of film conveyance during plastic film bag manufacture, line speeds of the passing plastic film are usually limited to 150 feet per second. In the manufacture of the disclosed bag, line speeds in the range of 300 feet per second can be tolerated. Hot seals produce permanent fusing of the plastic layers involved. Such permanent fusing can be detected by trying to separate the joined film layers. When such an attempt is made to separate the two layers joined by a hot seal, either joined film layer tears. The "hot seal" - composed of two layers fused one to another - does not tear and remains in tact. Regarding the use of a "cold seal", in the plastic bag manufacturing arts, there has been known for many years a defective seal known as a "cold seal." Such a cold seal has here to fore been an imperfect hot seal. Usually, the imperfect hot seal would be located at the bottom of a plastic bag. When load was placed in the plastic bag, the seal would part - and the bag contents drop to the ground, usually causing content loss and damage.

Cold seals as used in the specification that follows are easy to distinguish. Where a cold seal is present, it imperfectly seals two plastic film layers together. This imperfect fusing can be easily recognized. Film separation at the cold seal allows the two imperfectly fused film layers to separate. Each layer separates from the other layer without loosing substantial structural integrity of the film. Unlike the conventional "hot seal", neither of the previously fused film layers tears when separation occurs.

Cold seals have been used with plastic bags for joining bags loosely in a bundle. Such joinder usually takes place at the top of the bag adjacent the opening. In the typical application, separation of a bag from a bundle of bags at a cold seal usually assists in the opening of the bag.

Until this disclosure, no one has made a "cold seal" an important structural element of a bag! In addition to the "cold seal", this disclosure makes use of a preformed

"hinge" with the plastic film of the bag wall. Such hinges are capable of rapid formation by impressing the rapidly passing and planar film along a linear boundary. This impressing at the linear boundary leaves the film predisposed to "hinge" or fold at the boundary. The hinge that is here utilized is to be distinguished from a "fold." In folding, film is bent over and then creased so that it folds. Once this bending and creasing has occurred, the film is disposed to repeat the bending and folding along the crease.

The "hinge" here utilized is place in the plastic film of the bag wall while the film is planar or in the "lay flat condition" and passes through the bag machine at high speed. The placed linear hinge is typically either at right angles to the direction of film motion or alternatively diagonal to film motion. Thus the hinge here used, is not to be confused with side gusset creases that result from creased folds made in the direction of film passage. When the film is hinged - for the first time from the lay flat state to the erect disposition of the bag - the hinge structure impressed in the film predisposes the film to bend along the hinge axis. Through the combination of the hinge joining panels of plastic across the multiple flat surfaces of an erect bag, sufficient structural integrity is imparted to the bag to remain upright and open to receive and contain articles - such as fast food orders.

The reader should also understand that the difference between a "cold seal" and a "hinge" is not always precise. For example, where plastic film is passing a die at relatively high speed, and the dye come down upon two or more layers of plastic film, a hybrid "cold seal and hinge" can result. The cold seal will be recognizable by the imperfect fusing of the plastic layers one to another. The hinge will be recognizable by the reduction in thickness of the plastic film wall with the increased tendency of the film to fold at the hinge. It has been found that hybrid "cold seal" and "hinge" structures are produced in the bag production process herein set forth.

In the disclosure that follows, neither the "cold seal" nor the "hinge" incorporate or refer to bending and creasing film so that the film may bend again along the bend or the crease. In both the cases of the "cold seal" and "hinge", the film is at all times flat and planar when the "cold seal" or "hinge" is applied and introduced. This is known as the "lay flat" condition.

SUMMARY OF THE INVENTION An expandable plastic film gusseted bag includes a front panel of plastic film having two substantially parallel side edges; and a rear panel of plastic film having two substantially parallel side edges. Two front panel gussets of plastic film are used.

Each front panel gusset is connected to one of the two substantially parallel side edges of the front panel. Two rear panel gussets of plastic film are used. Each rear panel gusset connected to one of the two substantially parallel side edges of the rear panel. As in conventional bag manufacture, each front panel gusset connected to a rear panel gusset and usually each of the panel gussets are foldable between the front panel and the rear panel to provide a continuous bag periphery. A bottom joins the bottom of the front panel, rear panel, two rear panel gussets and two front panel gussets at substantial right angles to the side edges of the front panel, rear panel and gussets to close the bottom of the bag and leave only the top open. The improvement provides each plastic bag with eight first linear folding axes configured adjacent the bottom within each front panel and each front panel gusset and each rear panel and each rear panel gusset having one first linear folding axes. These folding axis extend from a joinder of a gusset at the bottom to the side edges of the front panel or the rear panel and the front panel gusset or the rear panel gusset at an oblique angle in the range of 45°. The folding axes are made by a process restricted to a group consisting of either a cold seal, a hinge, or a hybrid cold seal and hinge being placed in the plastic film while the film is planar or in the "lay flat" disposition. On opening of the expandable gusseted bag, the bottom seal of the bag disposed adjacent the gussets forms a generally triangular shaped overlay relative to the gussets to form a square bottom bag.

A process for bag manufacture of a bag having a first dimension from a sealed bottom of the bag to an open top of the bag, the bag being fabricated from a continuous tube of plastic film bag material. The process includes the steps of providing a continuous tube of plastic film bag material. The side edges of the bat material are folded between a front bag panel and a rear bag panel to form gussets. Preferably, the front bag panel and the rear bag panel are confronted to and in contact with one another at an inside surface of the front bag panel and the rear bag panel. A sealing station having apparatus for placing two parallel and spaced apart seals and a knife for cutting the continuous tube of the plastic film bag material between the two parallel and spaced apart seals. First adjacent double seals are formed across the front bag panel and the rear bag panel, the double seals in parallel side-by-side relation with one another with the plastic film bag material there between. These seals are cut across the continuous tube of plastic film bag material between the first adjacent double seals. The continuous tube of plastic film bag material is at least twice the first dimension from the sealed bottom of the bag to the open top of the bag. This forms second adjacent double seals across the front bag panel and the rear bag panel, the second adjacent double seals in parallel side-by-side relation with one another. By cutting the continuous tube of plastic film bag material between the second adjacent double seals, a double bag unit is formed and severed having single seals at opposite ends of the double bag unit with a continuous tube of plastic film bag material having two first dimensions between the single seals at opposite ends of the double bag unit.

A process of cold sealing two layers of plastic film material together is used as part of the structural element of a plastic bag made from plastic film. The plastic bag is formed with a front panel having two substantially parallel side edges; a rear panel having two substantially parallel side edges; and a fastening of the front panel and rear panel for forming a continuous periphery to the bag. It is required the plastic bag have a bottom joining the bottom of the front panel, and the bottom of the rear panel at substantial right angles to the side edges of the front panel and rear panel. This imparts to the bag a closed bottom, a continuous closed periphery, and an open top. The improvement provides the bag with a cold seal, which cold seal does not form a part of the closed bottom and continuous closed periphery of the bag. In the improved process, it is required that the first and second plastic films of the bag be confronted to one another in a disposition for sealing. Compression dies are provided on at least one side of the juxtaposed first and second plastic films, the compression dies are provided with the size and shape of the cold seal desired. Impressing of the compression dies across the juxtaposed first and second plastic films occurs. This impressing is at a temperature and pressure sufficient to fuse the first and second plastic films together. However, the impressing has insufficient temperature and pressure to permanently fuse the first and second plastic films together so that the films when separated at the cold seal each retain structural integrity. Embodiments are set forth where the cold seal is used as a structural element to square out square bottom bags. Specifically, the cold seal is provided with at least a linear disposition, which imparts to the cold seal the predisposition to fold or hinge at the boundary to cause opening to the square bottom shape.

One of the most important applications of this cold seal is the placement of a hinge. Specifically, two layers of plastic film are less than permanently joined together along a linear boundary. This joinder preferably occurs in the lay flat disposition while the bag is being manufactured. In this case, the cold seals are place where hinging of a square bottom plastic bag is required to predispose the bag to open with a square bottom.

When the bag is first opened by a clerk, the films joined at the top of the bag are parted from the lay flat disposition. Specifically, the clerk parts the front bag panel and the rear bag panel adjacent the opening, and then pulls the bag rapidly through the air. When the films are parted and air is introduced into what will become a square bottom bag, parting of the opened tissue occurs until the air penetrating the bag, reaches the cold seal.

When the air reaches the cold seal, the joined bag walls no longer separate. Instead, separation ceases at the cold seal and the material of the bag hinges at the cold seal. This hinging occurs because the bag continues to expand responsive to the in rush of air but is prevented by the cold seal from further separation at the cold seal. Thus, the present invention refers to a simple process of cold sealing plastic film that results in substantially the same effect as the heat sealing methods described in LaFleur '077, Hummel '565 and Roen '262 and the adhesive bonded bag of Watkins '829 (without the use of adhesive). It also relates to some of the resultant plastic bag products, more specifically flat bottom bags. However, the present invention reveals for the first time a means of cold sealing plastic film in a high-speed process with superior qualities than that provided by the aforementioned heat sealing or adhesive processes. This cold sealing process may be applied to the plastic bag film layers before it is cut and sealed into a bag of predetermined length, which then does not significantly affect line speed. Unlike the heat sealing methodology of La Fleur '077, Roen '262 and Hummel '565 which requires controlling 4 individual heat seals per bag, the present invention requires only one simple operation per bag—which operation can be simultaneously conducted on 3-5 lanes without significantly affecting line speed. Furthermore, this cold seal technology can be applied along with the hinging technology revealed in my co- pending application, Provisional Patent Application 60/088,613 filed June 9, 1998 by the named inventor herein entitled Plastic Film Hinging now Patent Application Serial No. 09/258,033 filed February 25, 1999 of even date herewith entitled Plastic Film Hinging and Precreasing Process is likewise incorporated by reference as if fully set forth herein. In these applications, hinges are used to produce a superior flat bottom, stand up bag. When doing so, the cold seals and the hinges are applied in the same single impressing operation. The reader will understand that the production of a hybrid cold seal and hinge is also possible. In this latter case, the imperfect joinder between two film layers also relates to the wall being thinned to form a hinge.

This cold sealing process is easily adapted to existing high-speed bag making equipment and technology— both bottom seal and sideweld. The methodology of applying angular cold seals to gussets also produces a seal that lies across the entire gusset pairs—right up to and even past the center gusset creases— which is virtually impossible with the prior art heat seal or adhesive technology. The present invention cold seal process applied to common plastic bags in a high-speed mode ensures great accuracy in consistently producing high quality, square bottom plastic bags that stand up

Applying the present invention as an angular gusset cold seal on the side gussets of bottom seal bags or the bottom gusset on sideweld bags gives a bag a temporary bond. This temporary bond enables the user to quickly find the bag bottom regardless of how he/she is opening and preparing the bag for use. With angular cold seals, the bottom portions of the side gussets on bottom seal bags will fold upon themselves, forming a flat base. Alternately, the cold seals may be applied to the outside portions of the bottom gusset on sideweld bags which portions will then fold upon themselves and form a flat base. Folding occurs whether this folding is by capturing air in a bag, shaking it, or by placing a hand inside the bag and pushing the gussets down at the bottom, the result is the same— a bag manufactured in the lay flat state that squares out and tends to stand up. It will be noted that the cold seals here disclosed may lose their bond after some repetitive reuse. However, plastic bags have a one time use requirement, especially the typical bags used in supermarkets, fast food chains and so on. Generally speaking, these carry out and point of purchase bags are only opened and filled one time. For instance, a bag used in a fast food restaurant is only filled once; a bag used for as a point of purchase bag for cookies is only filled once at the cookie factory.

The present invention also reveals for the first time a means of impressing hinges and temporarily cold sealing plastic film that can be precisely executed so that the impressions and temporary seals are accurately applied to predetermined panels or bag plies. Furthermore, the process of the present invention will reveal that these impressions and temporary seals may be perfectly registered as required in the bag making process. When impressing hinges and temporary cold seals to form stand up style bags, it is typically applied to the film in its lay flat condition, which— unlike prior art— entirely eliminates the cumbersome, time consuming folding methodologies or the heat sealing processes previously discussed. Furthermore, hinge impressing and temporary cold sealing are easily adapted to existing high-speed bag making equipment and technology—both bottom seal and side weld— and can be placed on multiple lanes without substantially affecting line speed. The process of applying hinging by cold seals may also be done simultaneously during one single impressing operation. The impressing and temporary seal processes can be applied to common plastic bags at present day high speeds and with great accuracy to consistently produce high quality, square bottom plastic bags that stand up.

The process of the present invention opens up new possibilities in the use of cold seal technology in the plastic bag and film industry. For instance, the hinging effect is also a reliable means to create new bag shapes and bottom configurations, such as bags with flat, octagonal, hexagonal or decagonal bottoms. As discussed in cross reference, hinges can cause the bottom portions of the side gussets on bottom seal bags will fold down upon themselves, forming a flat base. Or, hinges may be applied to the outside portions of the bottom gusset on side weld bags which portions will then fold out upon themselves and form a flat base. Used in concert with cold or warm temporary seals, the reliability in performance of the product may be significantly improved. Impressed hinges with accompanying cold or warm temporary seals can cause side weld bags to stand more upright and erect with their side welded ends folding inward, forming a squarer bag shape and improving the ability to load the bag. As illustrated in my co- pending Provisional Patent Application 60/088,613 filed June 9, 1998 by the named inventor herein entitled Plastic Film Hinging now Patent Application Serial No. 09/257,345 filed February 25, 1999 of even date herewith entitled Plastic Film Hinging and Precreasing Process is likewise incorporated by reference as if fully set forth herein. In this application, the impressing effect can also form an aesthetically appealing, registered embossing of a logo. The possibilities are endless.

The process of the present invention can also be reliably applied to laminated films and films that may be a combination plastic film and other materials such as foil or paper, for instance those used in point-of-purchase packaging. Many laminated films are made- of a thin layer of foil with a plastic outer or inner layer, frequently polyethylene. The two key variables in applying the present invention with films other than polyethylene are the temperature and the amount of pressure applied.

The impressing of hinges and applying cold or warm temporary seals is typically accomplished by applying pressure to a die upon a flat or round platen— or a die upon a matching, cooperating die— which in between lies one or more layers of plastic film. The process may also be effectively accomplished by the means of pressure embossing between rollers, one or more of which has a die impressing means. By using various combinations of dies, for instance male and female, male and male, two males and two females and so on various effects may be created. With heat being applied to the dies or rollers to create warm temperatures, the hinge or the temporary seal processes of the present invention are fast and highly effective and can easily keep up with the fastest high speed bag machines in the world.

A hinge is disclosed for a plastic film. This film has a predetermined thickness sufficient for the plastic film to remain planar in an absence of a first bending moment applied across the plastic film. The hinge includes at least one linear groove configured in the plastic film to reduce the predetermined thickness of the plastic film at the linear groove. The hinge permits preferential hinging of the plastic film at the linear groove responsive to a bending moment at the linear groove across the plastic film less than the first bending moment. The linear groove has insufficient depth to sever the plastic film and enables the hinge film to retain sufficient remaining thickness at the linear groove to permit hinging and not tearing of the plastic film at the linear groove. When the hinge is placed across a plastic film, and the film bent at the hinge, the film defines a first panel and a second panel with each panel disposed at an angle to one another at the hinge. This allows the first panel and the second panel to form a three dimensional structure to maintain the plastic film of each panel against bending. A square bottom bag design is disclosed where the hinge predisposes a plastic bag to open with a square bottom.

The present invention relates to simple process of hinging plastic film that results in substantially the same effect of the creasing or folding or heat sealing of plastic film discussed in the Description of Prior Art. Unlike the Prior Art, the hinge may be impressed in plastic film at relatively high speed. In this embodiment, a linear die may impart the required groove to plastic film as it passes at relatively high speed (about 300 feet per second). This process also is useful with plastic bag products. For example, the film can have a hinge precisely located at an angle to the direction of the passing film. The present invention reveals for the first time a means of hinging plastic film that can effect a unidirectional or bidirectional folding ability depending upon the desired effect. This hinging process may be applied to the plastic bag film before it is cut and sealed into a bag of predetermined length, which then does not significantly affect line speed. It is typically applied to the film in its layflat condition, which— unlike prior art— entirely eliminates the cumbersome, time consuming folding methodologies or the heat sealing processes previously discussed. Furthermore, this hinging process is easily adapted to existing high-speed bag making equipment and technology— both bottom seal and sideweld— and can be placed on multiple lanes without substantially affecting line speed. This hinging process can be applied to common plastic bags in a high-speed mode and ensures great accuracy to consistently produce high quality, square bottom plastic bags that stand up. The present invention also reveals new possibilities in the use of this technology in the plastic bag and film industry. For instance, the hinging effect can be used to create new bag shapes and bottom configurations, such as flat or square bottom bags and bags with octagonal bottoms. With the hinges, the bottom portions of the side gussets on bottom seal bags will fold down upon themselves, forming a flat base. Or, hinges may be applied to the outside portions of the bottom gusset on sideweld bags which portions will then fold out upon themselves and form a flat base. The hinges can cause sideweld bags to stand more upright and erect with their sidewelded ends turning inward, which forms a squarer bag shape and improving the ability to load the bag. The hinging effect can also be used to cause bottom seals to fold under when desirable and can cause bags to stand up more erect. The hinging effect can used to make predetermined structural creases to give bags more vertical rigidity and may also be used to make bag closures in a pre-determined location. The hinging effect can even be done to impress an aesthetically appealing, registered embossing of a logo. The possibilities are many.

When applied to square-bottom or stand up bags, bottom seal or sideweld, the hinge preferentially enables the bag to open and dispose the square bottom to a counter surface. At least through the action of the hinges, the plastic bag is disposed to stand open and upright while in the empty state. The user can quickly find the bag bottom regardless of how he/she is opening and preparing the bag for use. Whether this preparation for use be by capturing air in a bag, shaking it, or by placing a hand inside the bag and pushing the gussets down at the bottom, the result is the same— a bag that squares out at the bottom and tends to stands up.

The hinge can also be reliably applied to laminated films and films that may be a blend of plastic and other materials such as foil or paper, for instance those used in point-of purchase displays. Many laminated films are made of a thin layer of foil with a plastic outer or inner layer. By applying the present invention to these types of films, the result is the same, a square bottom bag. Creating square or rectangular packages of this nature would result in a substantial savings of shipping costs and shelf space, as more square packages can be packed in a given carton size than round packages.

The hinging process is typically accomplished by applying pressure to a die upon a platen— or a die upon a matching, cooperating die— which in between lies one or more layers of plastic film. Using various combinations of dies, for instance male and female, male and male, two males and two females and so on, various effects may be created.

For ease of explanation, only some of the particular uses of the present invention will be revealed herein, however, it would be easy for anyone trained in the art to find other applications, which would fall under the scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematic representation of a "cold seal" apparatus illustrating the diagonal placement of cold seal in rapidly passing planar film for causing the "imperfect" joinder of two layers of bag material;

Fig. 2 illustrates the separation of two "imperfectly fused" joined layers illustrating that upon separation of the layers that each of the separated layers retains its structural integrity;

Fig. 3 illustrates a "hinge" as it is here defined being placed within a plastic bag wall while the film is disposed in a planar condition;

Fig. 4 is a expanded side elevation section of the plastic film at the hinge illustrating the linear impression in the plastic film which leave the film when folded for the first time with the predisposition to fold along the linear axes of the fold;

Fig. 5 is a side elevation view of the plastic bag article of this invention illustrating in particular the placement of the "folding axes" (either hinges, cold seals, or both) in the side wall of a flat bottom plastic bag predisposing the bag to open and "flat out" when used for the first time;

Fig. 6 is a perspective view of the bag of Fig. 5 being opened and "flattened out" for the placement of articles into the bag; Fig. 7 is a so-called "side weld" bag shown having the hinge axes of this invention; and,

Fig. 8 is the side weld bag of Fig. 7 in the open disposition. Fig. 9is a plan view of a prior art process, which illustrates a typical bottom seal bag manufacturing process. Fig. 10 a plan view of a prior art process, which illustrates a typical sideweld bag manufacturing process. Fig. 1 Is a plan view of the present invention, which shows the process of die cutting preformed plastic tubes that are sealed at both ends, into independent stacks of common bottom sealed plastic bags.

Fig. 12 is a plan view of the present invention of Fig. 3, which shows the process of transferring the die cut stacks to a packing location.

Fig. 13 is a partial plan view of another means of transferring the two side- by-side bag stacks to a conveyor.

Fig. 14 is a partial plan view of a means of transferring the two severed and sealed portions through a two-step die-cutting operation. Fig. 15 is a plan view of a severed and sealed portion being die cut into two bag packs with die cut handles and a sculptured top made as made by the process of the present invention.

Fig. 16 is a plan view of a severed and sealed portion being die cut into two bag packs with double extended portions above the bag mouth as made by the process of the present invention.

Fig. 17 is a plan view of a severed and sealed portion being die cut into two bag packs with single extended portions above the bag mouth which single portions are offset on the opposing bag mouths of the bag packs, as made by the process of the present invention. Fig. 18 is a plan view of the present invention as it may be applied to the process of making plastic T-shirt style, handled grocery sacks.

Fig. 19 is a plan view of the present invention, which shows the process of die cutting preformed plastic tubes sealed at both leading and trailing edges, into independent stacks of common plastic sideweld bags with die cut handles. Fig. 20A is a partial plan view showing the application of angular bottom seals used to isolate the holes in the bag bottom created by a pin stacking process.

Fig. 20B illustrates the bag unit of Fig. 12A used for filling with cement or other granular contents through a pneumatic filling aperture.

DESCRIPTION OF THE SPECIFIC EMBODIMENTS

Referring to Fig. 1, double bag unit D is shown passing along bag production line B. This double bag unit D is sealed at both ends along leading seal SI and trailing seal S2. As will herein after be made clear, eventually, double bag unit D will be severed medial at medial cut C. This severance will allow an opening for each bag of the double bag unit D to occur in the center with flat bottoms at each end.

Double bag unit D is a gusseted bag construction. As such gussets G are attached between front panel P and rear panel R, they may be seen expanded in the view of Fig. 6. as panels 82, 84, 86 and 87 respectively. The reader will understand that the schematic of Fig. 1 is for the purpose of illustrating the placement of cold seals 20 and 21. All other features of the bag construction have been omitted.

Returning to Fig. 6, a typical flat bottom bag is illustrated. This includes the placement of cold seals or hinges 70 at the bottom portion of the illustrated and expanded bag. It will be developed that the hinging of the flat bottom bag illustrated in Fig. 6 can either be a hinge or a cold seal. For the purposes of Fig. 1 and 2, only the cold seals 21, 22 are considered.

Returning to Fig. 1, it is seen that die 24 having cold seal impressing ridges 25 and 26 overlies double bag unit D. For the purposes of Fig. 1, die 24 has been rotated up and away from double bag unit D so that ridges 25 and 26 are plainly visible. As is schematically illustrated, die 24 impresses on platten 22 with double bag unit D captured there between. Impressing of die 24 may be heated or done in the cold state. In any event there is an imperfect joinder of at least two layers of plastic material. To understand how this imperfect joinder operates, the readers attention is invited to Fig. 2. Referring to Fig. 2, two plastic layers 27, 28 are being separated from one another. Such separation easily occurs until cold seal 21 is reached. At cold seal 21, it will be found that the respective layers 27, 28 are imperfectly joined to one another. Easy separation will stop along the boundary of cold seal 21. If one continues to try and separate respective layers 27, 28 beyond cold seal 21, such separation will eventually be successful. Separation will occur to seal 21. Both respective plastic layers 27, and 28 will maintain their structural integrity. In the usual case, the broken cold seal will not appreciably weaken the layers 27,^' 28.

A brief preview of how cold seal/hinge 70 functions to allow the opening of a flat bottom bag is in order with quick reference to Fig. 6. Referring briefly to Fig. 5, and then to Fig. 6, it will be seen that when the flat bottom bag, cold seal represents a point of increased resistance only to opening of the bag. This is sufficient to cause the bottom of the bag to "flat out" during the opening process. I have also discovered that the placement of a hinge in location 70 of the illustrated flat bottom bag has the same effect. Specifically, and referring to Fig. 3, plastic film 28 is impressed with hinge H. Impression occurs between die 40 and platten 42. As before, die 40 has ridge 41 extending across the bottom of the die in the path of hinge H. Again, the path of hinge H is linear and constitutes a reduction in thickness of film 28 along the axis of hinge H.

Refer again to Figs. 5 and 6. Assume that instead of cold seals 20, 21, hinge H is placed at cold seal/hinge 70 at the bottom of flat bottom bag. Again squaring of the bag B will occur. In other words, either a cold seal such as cold seals 20, 21 or hinge H will predispose the bag article of Fig. 5 to open as the flat bottom bag illustrated in Fig. 6.

Taking the case of the open flat bottom bag, it will be remembered that the production here illustrated forms the bag completely in flat and planar state. When the bag moves to the disposition shown in Fig. 6, the bag is opened for the first time. This being the case, it will be realized that cold seal/hinge 70 need only be highly transitory. In short, they need to work only once.

Further, it will be understood that both the cold seal and the illustrated hinge do not have to have the full strength of the plastic film to operate satisfactorily. All that needs to happen is to have their respective formation add to the bag the predisposition to open and flat out at the bottom. Once this is achieved, the bag can be conventionally loaded and conventionally used.

It should be understood that the hinge or cold seal used with this invention can be hybrid. In this case, impressing of a cold seal may reduce the thickness of the plastic film giving the bag a tendency to "hinge" along the cold seal. At the same time, the vicinity of the hiήge may result in an imperfect bond along the linear hinge axis with adjoining sheets of plastic film. This imperfect bond coupled with the "hinge effect" causes the film processed in the "lay flat" disposition to open and form preferentially a flat bottom contour.

Having said this much, the remaining structure of the illustrated bag can be described. Turning Fig. 5, the bag has open top 62, front panel 63, front panel gussets 64, 66 with central gusset fold 74, 80. The bag includes sealed bottom 68-72. In accordance with the preferred embodiment, hinges 65, 75 are impressed in the bag front panel 63 and rear panel 62. These hinges have been shown to react to a panel type hinging to impart additional strength to the bag.

Referring to Fig. 6, the open bag is shown with its flat bottom. It includes gussets 64, 66 extending between front panel 63 and rear panel 62. It will be seen that these respective gussets 64, 66 are in the full open position imparting to the bag a flat profile from the opening toward the bag bottom. At the bag bottom, characteristic triangular folds 90 will form. These characteristic folds dispose the bag with its flat bottom resting downward. In fact, after opening an empty bag from the disposition shown in Fig. 5, to that of Fig. 6, it has been demonstrated that the bag physically rests in the disposition of Fig. 6. In short, a clerk may load the open bag at the bottom without fear of bag collapse to the closed position.

In Fig. 7 side weld bag 200 has a top 202, a front panel 203, a rear panel (not shown), a die cut handle 205, a bottom gusset 204 and its center gusset crease 206, and side welded edges 208 and 210. At 45 degree angles in both outer regions of bottom gusset 204 are hinge axes 212 and 214 which respectively terminate approximately at the point where center crease 206 crosses side weld 208 and where center crease 206 crosses side weld 210. A vertical bi-directional hinge 216 begins at point 218 and terminates at point 220 and another bi-directional hinge 222 begins at point 224 and ends at point 226, both of which hinges have been impressed upon front wall 203, rear bag wall (not shown) and bottom gusset 204.

In Fig. 8, the side weld bag 200 of Fig. 7 has been opened and sets upright upon bottom gusset 204 , Linear hinge axes 212 and 214 cause the lower outer regions 230 and 232 respectively to turn upright and help flat out the bottom gusset assisting in the formation of a flat base. In turn, bi-directional hinge 216 causes the upper outer region 234 to stand up and box out and side weld 208 to cooperate by turning inward. Hinge 222 causes its respective upper outer region 236 to stand up and box out and side weld 210 to cooperate by turning inward. Bag 200 is now ready to be loaded.

It is easy to see that cold sealing the bottom gusset in side weld bags has a similar outcome as cold sealing the side gussets in bottom seal bags described in Figs. 5, and 6.

Some attention should be given to the linear hinge axis which is at an oblique angle - most preferably 45°. It will be understood that variations in this angle can occur. For example, the angle can easily vary in the range of 40° to 50°. Further, both of the oblique axes do not have to be identical. They may each vary by differing amounts. All that is required is that the axes produce a tendency of the bag which is manufactured in the lay flat condition to hinge and open with a flattened out bottom.

In Fig. 9 the prior art bottom seal process begins with a flattened tube T, which is slit sealed S into two smaller flattened tubes T' and T", which smaller tubes are side gusseted at locations G' and G". After each individual bag is bottom sealed and severed at bottom seal bar Bl, the bags are stacked up at location L' and L", which stacks (typically of 50 bags or so) are grasped by fingers sets F' and F" and transported to die- cutting station Cl. After die cutting, the bag stacks are typically moved to a conveyor belt or packing station, in which the die cut bag stacks are loaded into shipping cartons. In this prior art example the bags being manufactured are die-cut handled Dual-tab bags like those described in U.S. Patent 4,759,639.

In Fig. 10 prior art sideweld process begins with a flattened tube R, which is slit open at edge E, bottom gusseted P, which tube R is then sidewelded DI into individual bags, which bags are stacked up at location M. These bag stacks are typically picked up by an employee who may die cut the bag stack at manual die cutting press N, in this illustration forming die cut handles HI and sculptured shoulders V and V".

In Fig. 11 the present invention bottom seal process begins with a flattened tube 110, which is slit sealed by slit-seal knife 112 into two smaller flattened tubes 114 and 114', which smaller tubes 114 and 114' are then side gusseted 116 and 118 and 116' and 118' respectively. Tubes 114 and 114' are then fed through bottom sealer 120 which sealer 120 makes two lateral seals (not shown) across tubes 114 and 114' and simultaneously severs tubes 114 and 114' between the two seals, creating two side-by- side, severed and sealed portions 122 and 122', which portions have been transported forward and stacked up, typically into stacks of 50 or so. Severed and sealed portions 122 and 122' have lateral seals 124 and 126 and 124' and 126' respectively at both ends and gussets 116a and 118a and 116a' and 118a' respectively on their sides. One step forward in the process, two side-by-side severed and sealed portions have been transported by clamping fingers 142 and 144 and 142' and 144' respectively, to an intermediate point under die cutter 130, which die cutter 130 is shown as having die cut the two side-by-side severed and sealed portions into four individual bag stacks 132a and 132b and 132a' and 132b' by knife 131 and has die cut handles holes 133a, 133b, 133a' and 133b' respectively. Each bag stack 132a, 132b, 132a' and 132b' has side gussets 136a and 138a, 136b and 138b, 136a' and 138a', and 136b' and 138b' respectively, and lateral seals 134, 136, 134' and 136' respectively, which lateral seals have formed bag bottoms 140a, 140b, 140a' and 140b'. From this die cut operation, the bag stacks 132a, 132b, 132a' and 132b' would be transported to a loading station. This illustration shows that two slit sealed tubes can be made into four bag packs during a single cycle of the bag machine's operation. It also illustrates that the die cutting operation has the tremendous flexibility of creating virtually any style of bag and is not limited to interconnected, detachable bags. For instance, in addition to detachable bags, it may form bags with flush tops and no handles, bags with die cut handles, bags with sculptured shoulders, bags with a multitude of tab designs, T-shirt style plastic grocery sacks and so on. As is further described in the following Fig. 12, the continued process of the present invention will also eliminate the need or the extra labor required to tear apart interconnected detachable bags at a weakened tear line. It should also be understood that the process of the present invention may be applied to a tube that has been slit sealed into more than just two smaller tubes, for instance, three, four or even five tubes. In such a case, three, four or five tubes would then be converted into six, eight or ten individual bag stacks.

In Fig. 12 the process of Fig. 11 shows bag stacks 132b and 132b' have been already transported from the die cutter 130 to a packing station by fingers 142, 144, 142' and 144' respectively (see Fig. 11 to view location of Fingers 142, 144, 142' and 144' just before the transportation of bags stacks 132b and 132b'). Fingers 142, 144, 142' and 144' are now shown in position to grasp the second sets of bag stacks 132a and 132a', which bag stacks will also be transported to the same packing station where bag stacks 132b and 132b presently lie. Fingers 142, 144, 142' and 144' are typically a part of a movable carriage system that grasps and transports bags along the production line. In the process of the present invention, the fingers and carriage system will cycle twice during any one die cutting operation instead of only once, as would be the case with prior art.

In Fig. 13 a variation on transporting the bag stacks is illustrated by four sets of fingers, which fingers 152a and 154a grasp bag stack 132a, fingers 152b and 154b grasp bag stack 132b, fingers 152a' and 154a' grasp bag stack 132a', and fingers 152b' and 154b' grasp bag stack 132b', all of which fingers and bags stacks are simultaneously transported to a packing station (not shown). It is important to note that there are other transportation possibilities in the process of the present invention, for instance, the bag stacks may be grasped by two sets of fingers in which each set grasps two stacks simultaneously. The present invention is not intended to be limited by the means of bag stack transport.

In Fig. 14 two severed and sealed portions 162 and 162' have been transported to an intermediate point at first die cutting station 164 in which die cut handle holes 166 and 168 and edge portions 170 and 172 have been cut and extracted (handle hole slugs not shown) from severed and sealed portion 162, and; die cut handles 166' and 168' and edge portions 170' and 172' have been cut and extracted (handle hole slugs not shown) from severed and sealed portion 162'. Severed and sealed portions 162 and 162' remain connected via bridges 173 and 173' respectively. The arrows then show the same two severed and sealed portions 162 and 162' as they have been subsequently transported (arrows) by fingers 175 a and 175b, and 175 a' and 175b' respectively, to an intermediate point at second die cutting station 174 in which knives 176 and 176' of die cutting station 174 have severed the two portions 162 and 162' at their respective bridges 173 and 173' (before severance) forming four individual bag stacks 162a, 162b, 162a' and 162b'. This second die cutting operation is conducted near the bag packaging station, to which the bag stacks may be easily delivered by fingers to a conveyor belt or even dropped right upon the conveyor belt once severed. Or, the bag stacks themselves may be dropped directly on the belt itself or even manually removed from the second die cutting station and packed into shipping cartons. In this two-step operation, it is also ideal for heat sealing tabs if desirable, or releasably bonding bag packs as discussed in my co-pending Provisional Patent Application 60/089,582 filed June 17, 1998 by the named inventor herein entitled Plastic Bag Bundling System now Patent Application Serial No. 09/258,010 filed February 25, 1999 of even date herewith entitled Plastic Bag Bundling System is likewise incorporated by reference as if fully set forth herein. In Fig. 15 severed and sealed tube portion 180 has opposing bottom seals

182 and 184 and has been die cut at an intermediate point to form opposing bag tops 186 and 188, die cut handles 190 and 192, and sculptured shoulders 194 and 196 and 194' and 196', all together which form two opposing bag stacks 182a and 182b. In the center of the opposing bag tops 186 and 188 and the opposing sculptured shoulders 194 and 196 and 194' and 196' is slug 198 (shade lines), which is a result of the die cutting operation. After the die cutting operation has been completed, slug 198 and slugs 191 and 193 (shade lines) formed from the die cutting of handles 190 and 192 are all typically pushed into a recycling (or reprocessing) bin, which contents are later reprocessed into finished product. From this die cutting operation, the bag stacks are transported as previously described to a packing station.

In Fig. 16 severed and sealed tube portion 300 has opposing bottom seals 302 and 304 and has been die cut at a intermediate point to form opposing bag tops 306 and 308 and double extended portions 310, 310', 312 and 312' at the opposing bag tops 306 and 308 respectively, all together which form two opposing bag stacks 302a and 302b. The extended portions 310, 310', 312 and 312' are shown separated and defined by cut lines 314 and 314' respectively, which cut lines may have been made from either the single or two-step die cutting process previously described. In the center of the extended portions 310, 310', 312 and 312' are mounting holes 316, 318, 316' and 318' respectively. Slugs 320, 322 and 324 (shaded lines) will be removed and reprocessed once again in the same manner as previous discussed. These bags with double extended portions have been made according to my co-pending Provisional Patent Application 60/089,582 filed June 17, 1998 by the named inventor herein entitled Plastic Bag Bundling System now Patent Application Serial No. 09/258,010 filed February 25, 1999 of even date herewith entitled Plastic Bag Bundling System is likewise incorporated by reference as if fully set forth herein.

Fig. 17 severed and sealed tube portion 330 has opposing bottom seals 332 and 334 and has been die cut at an intermediate point to form opposing bag tops 336 and 338 and single off-set extended portions 340 and 342 at the opposing bag tops 336 and 338 respectively, all together which form two opposing bag stacks 332a and 332b. The extended portions 330 and 332 are shown separated by cut line 334a, which cut line may have been made from either the single or two-step die cutting process previously described. In the center of the extended portions 330 and 332 are mounting holes 346 and 348 respectively. Slugs 350 and 352 (shaded lines) will be removed and reprocessed in the same manner as previous discussed. These bags with single extended portions have been made according to my co-pending Provisional Patent Application 60/089,582 filed June 17, 1998 by the named inventor herein entitled Plastic Bag Bundling^" System now Patent Application Serial No. 09/258,010 filed February 25, 1999 of even date herewith entitled Plastic Bag Bundling System is likewise incorporated by reference as if fully set forth herein.

In Fig. 18 the present invention bottom seal process begins with a flattened tube 460, which is slit sealed by slit-seal knife 462 into two smaller flattened tubes 464 and 464', which smaller tubes 464 and 464' are then side gusseted 466 and 468 and 466' and 468' respectively. At seal location 469, gusseted tubes 414 and 414' are sealed laterally at 471a, 471b, 473a and 473b, and 471a', 471b', 473a' and 473b' respectively. These lateral seals 471a, 471b, 473 a and 4173b, and 471a', 471b', 473 a' and 473b' traverse the gussets 466, 468 and 466' and 468' as illustrated. Tubes 464 and 464' are then fed through bottom sealer 470, which sealer 470 makes two more lateral seals (not shown) across the entire width of tubes 414 and 414' entirely and simultaneously severs tubes 414 and 414' between the two seals, creating two side-by-side, severed and sealed portions 472 and 472', which portions respectively have lateral seals 471a, 471a, 471b, 473a and 473b, and 471a', 471b', 473a' and 473b' at an intermediate location and which severed and sealed portions 472 and 472' are stacked up into a typical stack of 50 bags or so. As illustrated, stacked up severed and sealed portions 472 and 472' have lateral seals 474 and 476, and 474' and 476' respectively, at their ends, which lateral seals were made at bottom sealer 470 and extend across the entire width of the portions 472 and 472', and; portions 472 and 472' have gussets 466a and 468a and 466a' and 468a' respectively on their sides. One step forward in the process, the two side-by-side severed and sealed portions have been transported by any of the means previously described to an intermediate point under die cutter 480, which die cutter 480 is shown as having die cut the two side-by-side severed and sealed portions into four individual bag stacks 482a and 482b and 482a' and 482b' (shown in its view after being die cut and as separated from the die cut operation) by rectangular central die cut knives 481a and 481b (not shown) and their respective blades 483a and 485a, and 483b and 484b (not shown), which blades 483a and 485a are shown cutting right in between the two pairs of lateral seals 471a and 471b and 473a and 473b. Die cuts 481a and 481b have formed handled T-shirt style bags much like those described in U.S. Patent 4,676,378 Baxley, with outer opposing strap handles Y and a central bag mouth region Z. Die cutting this type of bag pack may be done in either a single or two-step die cutting operation. The die cut between the lateral seals (as shown in 483a and 485a) forming the haridles may also be done at the sealing station 469. What is most important is to illustrate that the two slit sealed tubes can be made into four bag packs and also illustrates the tremendous flexibility of forming various bag styles without interconnecting the bags with a weakened tear line. It should be understood that this bag making process may also be applied to a tube that has been slit sealed into more than just two smaller tubes, for instance, three, four or even five tubes. In such a case, three, four or five tubes would then be converted into six, eight or ten individual bag stacks. In forming plastic grocery sacks of this style, using a two-step die cutting process may also be advantageous. The first step may die cut the handle portions thereby forming the two side-by-side bag packs, and the second step may sever the bag packs entirely while simultaneously releasably bonding the bag packs together.

In Fig. 19 the present invention sideweld process begins with a flattened tube 510, which is then gusseted 516 and 518 respectively. Tube 510 is then fed through bottom sealer 520 which sealer 520 makes two lateral seals (shown as sealed side edges 521 and 523) which seals 521 and 523 simultaneously cuts tube 510 into severed and sealed portion 522, which portion 522 has been stacked up into a stack of typically 50 bags or so. Severed and sealed portion 522 now has lateral seals 521 and 523 on its side regions and gussets 516 and 518 on its outer top and bottom regions. One step forward in the process, the severed and sealed portion 522 is shown transported to an intermediate point under die cutter 530, which die cutter 530 is shown as having die cut the severed and sealed portion 522 into two individual bag stacks 532a and 532b at cut line 534, which bag stacks 532a and 532b have die cut handles holes 533a and 533b respectively. Each bag stack 532a and 532b has bottom gussets 536a and 536b respectively, and lateral sealed edges 538a and 539a and 538b and 539b respectively, and die cut line 534 has formed two bag tops 540a and 540b respectively. From this die cut operation, the bag stacks 532a and 532b would be transported to a loading station by fingers 546a and 548a, and 546b and 548b respectively, as shown in the sequence. The bag stack transportation means may be any of those previously described. This illustration shows that a single sidewelded tube can be made into two bag packs during a single cycle of the bag machine's operation. It also illustrates the tremendous flexibility of the die cutting operation, forming virtually any style sideweld bag and also is not limited to interconnecting the bags. For instance, in addition to sideweld bags illustrated, they may have flush tops and no handles, may have sculptured shoulders with handles, and may even be a form of T-shirt bag. In a similar manner as has been previously described the sideweld process of the present invention may also be applied to two, three, four or even five tubes. In such a case, three, four or five tubes would then be converted into six, eight or ten individual bag stacks.

In Fig. 20A severed and sealed bag portion 550 is shown after it has left bag bottom sealer 552 and stacked up on stacking pins 554 and 556. At the lower outer corners of severed and sealed bag portion 550 are angular seals 558, 560, 562 and 564. These seals may have been made much like those described in U.S. Patent 3,915,007 LaFleur, or in my co-pending Provisional Patent Application entitled Cold Sealing of Plastic Film 60/088,612 filed June 9, 1998 by the named inventor herein now Patent Application Serial No. 09/257,848 filed February 25, 1999 of even date herewith entitled Apparatus and Process for Cold Seal in Plastic Bags is likewise incorporated by reference as if fully set forth herein.

Angular seals 558 and 560 serve to confine the holes made by stacking pins 554 and 556 into the outer portions 566 and 568. These outer portions 566 and 568 will be located at the eventual bag bottoms underneath the folded over gussets and are not vulnerable to stress when the bag will be subsequently loaded, which therefor, the holes formed at stacking pin locations 554 and 556 will not be vulnerable to breaking when place under load. The isolation of stacking pins may be accomplished in a variety of means, but the one illustrated in Fig. 20A would be a preferred means, since the angle seals also provide a desirable, primary function. One of the keys to the process of the present invention with pin stacking systems, is to place the pin stacking means towards the outer, lower regions where the holes could then be isolated and not be vulnerable to tearing under stress— unlike being located in the middle region where pin stacking holes would readily tear once the final bag product were placed under load. It will be seen that outer portions 566 and 568 meet this condition of not being subject to tearing when the bag is loaded. Similarly, the portions of the front panel can meet this limitation.

Fig. 20B illustrates an interesting bag unit. Specifically by placing a pneumatic nozzle 569, the bag unit of Fig. 20A can be filled as illustrated in Fig. 20B. Filling occurs in - for example - triangular portion 256 - with the triangular portion being severed for hinge like motion with respect to the double bag unit. Later, when the double bat unit is filled and stacked, triangular portion 556 hinges closed under the force of cement trying to escape the bag. A self seal bag unit results.

Referring to Figs. 21 and 22, two types of seals are illustrated. Referring to Fig. 21, a known seal called a slit seal is illustrated. Knife-edge 600 heated between 400 and 1000 degrees F periodically comes down on roller 602 with bag material 608 passing between the knife-edge and roller. This leaves two seal beads 604, 606 sealing the bottom of the respective bags. Similarly, and if Fig. 22, a broad conventional hot seal is impressed by heated bar 610 on platen 612 on bag material 608. The broad heat seal 610 results. This broad heat seal is cut by down stream knife 613. Naturally, various other combinations of seal and knives will work with this described invention.

From the foregoing descriptions of the process and the many applications of using the process of the present invention, as illustrated in both bottom seal and sideweld applications, it will be appreciated that the number of new applications are many. It is not the intention of the present invention to be limited solely to the film products illustrated herein or to the two individual processes, but to be used in whatever conceivable manner to improve the performance of a plastic bag, sheet, film, laminated film, or blended film manufacturing processes. For instance, any of the processes described herein may be used in lap seal or certain pouch applications as well.

It should also be understood that the means of stacking bags may include any number of possibilities, such as pin stacking, clamping, containing, paddlewheel stacking and so on. The result is still substantially the same as described herein.

Furthermore, it should also be understood that the means of transporting the bag stacks from and to die cutter and packing station may be any number of already acceptable means such as clamping with fingers on carriages, paddlewheel transport, conveyor belts and so on.

Claims

WHAT IS CLAIMED IS:

1. In combination an expandable plastic film gusseted bag having: a front panel of plastic film having at least one substantially linear side edge; a rear panel of plastic film having at least one substantially linear side edge; at least one front panel gussets of plastic film, each front panel gusset connected to one of the linear side edges of the front panel; each rear panel gusset connected to at least one of side edges of the rear panel; each front panel gusset connected to a rear panel gusset; each of the panel gussets foldable relative to the front panel and the rear panel; and, an improvement providing the expandable gusseted bag with a flat bottom comprising: eight first linear folding axes configured adjacent the bottom within each front panel and each front panel gusset and each rear panel and each rear panel gusset having one first linear folding axes; each folding axis extending from substantially a joinder of a gusset at an approximate oblique angle, each folding axes selected from a group consisting of a cold seal, a hinge, or a hybrid cold seal and hinge; whereby on opening of the expandable gusseted bag the bottom seal of the bag disposed adjacent the gussets forms a generally triangular shaped overlay relative to the gussets to form a flat bottom bag.

2. In combination an expandable plastic film gusseted bag according to claim 1 having in further combination: a first folding axis and a second folding axis, each folding axis extending from a central portion of the expandable gusseted bag adjacent the bottom to a peripheral portion of the expandable gusseted bag adjacent a joinder of the gusset to the panel; the first folding axis on one side of the bag configured in overlying relation in the front panel, the front panel gusset, the rear panel gusset, and the rear panel; the second folding axis on an opposite side of the bag configured in overlying relation in the front panel, the front panel gusset, the rear panel gussets and the rear panel; and, the bottom of the bag has a hot seal.

3. In combination an expandable plastic film gusseted bag according to claim 1 having in further combination: a first folding axis and a second folding axis, each folding axis extending from a central portion of the expandable gusseted bag adjacent the bottom to a peripheral portion of the expandable gusseted bag adjacent a joinder of the gusset to the panel; the first folding axis on one side of the bag configured in overlying relation in the bottom, the front panel, the rear panel, and the bottom; the second folding axis on an opposite side of the bag configured in overlying relation in the bottom, the front panel, the rear panel, and the bottom; and, the side of the bag has a hot seal.

4. In combination an expandable plastic film gusseted bag according to claim 1 having in further combination: the front panel, rear panel and gussets each including a plastic film having a predetermined thickness sufficient for the plastic film to remain planar in an absence of a first bending moment applied across the plastic film; the first linear folding axis each including at least one linear groove configured in the plastic film to reduce the predetermined thickness of the plastic film at the linear groove and to permit preferential hinging of the plastic film at the linear groove responsive to a bending moment, the linear groove having insufficient depth to sever the plastic film and retaining sufficient remaining thickness at the linear groove to permit hinging and not tearing of the plastic film at the linear groove.

5. In combination an expandable plastic film gusseted bag according to claim 1 having in further combination: the front panel, rear panel and gussets each including a plastic film having a cold seal to an adjacent layer of film to cause folding of the film adjacent the cold seal.

6. In combination an expandable plastic film gusseted bag according to claim 1 having in further combination: at least eight second linear folding axes configured in each front panel, front panel gusset and rear panel and rear panel gusset, the at least eight second linear folding axes beginning at a junction of the first hinge to gussets and extending centrally of the bag to permit respective folding of the front panel, rear panel, front panel gussets and rear panel gussets to form the flat bottom of the bag.

7. In combination an expandable plastic film gusseted bag according to claim 5 having in further combination: at least eight second linear folding axes are slightly angularly inclined to the side edges of each front panel, front panel gusset, rear panel and rear panel gussets.

8. In combination an expandable plastic film gusseted bag according to claim 1 having in further combination:

the oblique angle is 45┬░.

9. A process for bag manufacture of a bag having a first dimension from a sealed bottom of the bag to an open top of the bag, the bag being fabricated from a continuous tube of plastic film bag material; the process comprising the steps of:

providing a continuous tube of plastic film bag material with the front bag panel and the rear bag panel confronted to and in contact with one another at an inside surface of the front bag panel and the rear bag panel;

providing a sealing station having apparatus for placing two parallel and spaced apart seals and a knife for cutting the continuous tube of the plastic film bag material between the two parallel and spaced apart seals;

forming first adjacent double seals across the front bag panel and the rear bag panel, the double seals in parallel side-by-side relation with one another with the plastic film bag material there between;

cutting the continuous tube of plastic film bag material between the first adjacent double seals; advancing the continuous tube of plastic film bag material at least by twice the first dimension from the sealed bottom of the bag to the open top of the bag;

forming second adjacent double seals across the front bag panel and the rear bag panel, the second adjacent double seals in parallel side-by-side relation with one another; and,

cutting the continuous tube of plastic film bag material between the first and second adjacent double seals whereby a double bag unit is formed and severed having single seals at opposite ends of the double bag unit with a continuous tube of plastic film bag material having two first dimensions between the single seals at opposite ends of the double bag unit.

10. A process for bag manufacture of a bag according to claim 9 and having the additional step of: forming gussets join the front bag panel and the rear bag panel.

11. A process for bag manufacture of a bag according to claim 9 and having the additional step of: forming the gussets between the front bag panel and the rear bag panel.

12. A process for bag manufacture of a bag according to claim 9 and .having the additional step of: medially cutting the double bag unit at a medial portion of the double bag unit between the single seals at opposite ends to form two bags from the double bag unit.

13. A process for bag manufacture of a bag according to claim 12 and wherein: stacking of the bag unit occurs.

14. A process for bag manufacture of a bag according to claim 13 and wherein: the stacked bag units are transported for packing.

15. A process for bag manufacture of a bag according to claim 13 and wherein: stacking a plurality of double bag units before the medially cutting step.

16. A process for bag manufacture of a bag according to claim 13 and wherein:

stacking a plurality of double bag units after the medially cutting step

17. A process for bag manufacture of a bag according to claim 13 and wherein:

stacking the bags to pins in portions of the bag not subject to tearing when the bag is loaded.

18. A process for bag manufacture of a bag according to claim 9 and wherein: the side edges folded between a front bag panel and a rear bag panel have gussets.

19. A process for bag manufacture of a bag according to claim 12 and wherein: the medially cutting the double bag unit step includes excising portions of the double bag unit in the medial portion of the double bag unit.

20. A process for bag manufacture of a bag according to claim 12 and wherein: the medially cutting the double bag unit at a medial portion of the double bag unit step includes: placing a central aperture in the medial portion of the double bag unit; placing two side apertures in the medial portion of the double bag unit; forming parallel double seals in the plastic film bag material on either side of the central aperture; and, cutting between the parallel double seals in the plastic film bag material to sever the double bag unit to form "T" shirt bags.

21. A process for the manufacture of a bag comprising the steps of: providing a double bag unit having a front bag panel and a rear bag panel with the front bag panel and the rear bag panel confronted to and in contact with one another at an inside surface of the front bag panel and the rear bag panel, the provided double bag unit having single seals at opposite ends of the double bag unit with a continuous tube of plastic film bag material between the ends; medially cutting the double bag unit at a medial portion of the double bag unit between the single seals at opposite ends to form an open end of two bags from the double bag unit.

22. A process for bag manufacture of a bag according to claim 9 and wherein: side edges folded between a front bag panel and a rear bag panel have gussets.

23. A process of cold sealing two layers of plastic film material together comprising the steps of: forming a plastic bag, the plastic bag including a front panel of plastic film having two substantially parallel side edges; a rear panel of plastic film having two substantially parallel side edges; a fastening of the front panel and rear panel for forming a continuous periphery to the bag; and, a bottom joining a bottom of the front panel, and a bottom of the rear panel at substantial right angles to the side edges of the front panel and rear panel; whereby the bag has a closed bottom, a continuous closed periphery, and an open top; an improvement providing the bag with a cold seal which does not form a part of the closed bottom and continuous closed periphery of the bag, the process comprising the steps of: juxtaposing at least first and second plastic films of the bag to one another in a disposition for sealing; providing at least one compression die on at least one side of the juxtaposed at least first and second plastic films, the compression die having the size and shape of the cold seal desired; impressing the compression die across the juxtaposed first and second plastic films to produce a temperature and pressure sufficient to fuse the at least first and second plastic films together, the impressing having insufficient temperature and pressure to permanently fuse the first and second plastic films together so that the films when separated at the cold seal each retain structural integrity.

24. A process of cold sealing two layers of plastic film material together according to claim 23: the provided compression die includes first and second compression dies on opposite sides of the plastic film acting in opposition to one another.

25. A process of cold sealing two layers of plastic film material together according to claim 23: intermittently advancing and stopping plastic films in juxtaposition to be sealed; and, impressing the plastic films in juxtaposition when at least first and second films are stopped.

26. A process of cold sealing two layers of plastic film material together according to claim23: providing at least one die mounted to a rotating support; advancing plastic film to be cold sealed under the die; rotating the support for the die to apply impressing to the plastic film at substantially the velocity of the passing film whereby the cold seal is placed to the plastic film while the plastic film is advancing.

27. A process of cold sealing two layers of plastic film material together according to claim 23 and wherein: forming the plastic bag after the impressing step for the cold seal.

28. A process of cold sealing two layers of plastic film material together according to claim 23 comprising the additional steps of: the provided at least one compression die is configured for placing a groove in at least one of the at least first and second plastic films.

29. A process of cold sealing two layers of plastic film material together according to claim 28 comprising the additional steps of: the provided at least one compression die is configured for placing compression over an area of the juxtaposed at least first and second films.

30. In a plastic film having a predetermined thickness sufficient for the plastic film to remain planar in an absence of a first bending moment applied across the plastic film, the improvement of a hinge comprising: at least one linear groove configured in the plastic film to reduce the predetermined thickness of the plastic film at the linear groove and to permit preferential hinging of the plastic film at the linear groove responsive to a bending moment at the linear groove across the plastic film less than the first bending moment; and, the linear groove having insufficient depth to sever the plastic film and retaining sufficient remaining thickness at the linear groove to permit hinging and not tearing of the plastic film at the linear groove.

31. The improvement of a hinge in a plastic film according to claim 30 comprising: the linear groove is a "V" shaped linear groove.

32. The improvement of a hinge in a plastic film according to claim 30 comprising: at least two side-by-side and parallel linear grooves are configured in the plastic film.

33. The improvement of a hinge in a plastic film according to claim 32 comprising: at least one linear groove is configured from one side of the plastic film and the other linear groove is configured in parallel relationship from an opposite side of the plastic film.

34. The improvement of a hinge in a plastic film according to claim 33 comprising: each linear groove underlies a remaining linear groove.

35. The improvement of a hinge in a plastic film according to claim 32 comprising: at least two linear grooves are configured in side-by-side parallel relationship from one side of the plastic film.

36. The improvement of a hinge in a plastic film according to claim 30 comprising: at least three linear groove are configured in side-by-side parallel relationship in the plastic film.

37. The improvement of a hinge in a plastic film according to claim 30 comprising: at least two linear grooves are configured from one side of the plastic film and at least one linear groove is configured from an opposite side of the film.