Abstract:
A tubular sleeve having an open top, a closed bottom wall, a front and back faces and a pair of opposing side walls connecting the front and back faces. The side walls are formed with at least one gusset allowing the front and back faces to extend from each other. 
     The gussets are sealed unitarily at the bottom ends to form the bottom wall. The “square bottom” bag takes on a triangular lengthwise shape normally biased closed at the top but easily openable for maximum filling and discharge of the interior of the bag.

Description:
RELATED APPLICATIONS 
   The present application contains disclosures found in applicant&#39;s earlier in U.S. Pat. No. 3,988,970, U.S. Pat. No. 3,916,770 and U.S. Pat. No. 4,230,300 issued a “square bottom” or “flat bottom” plastic bag and Provisional Patent Application No. 60/365,028 dated Mar. 18, 2002 and Disclosure Documents #492644 dated Apr. 23, 2001 and No. 492645 dated Apr. 23, 2001. 
   BACKGROUND OF THE INVENTION 
   The present invention relates to the closure of open top, thin plastic, gussetted bags including a “square bottom” plastic bag, “T” shirt bag and any top opening bag with side gussets formed of thin plastic material. 
   Plastic gussetted “square bottom” or “flat bottom” bags and regular gussetted bags have supplanted paper bags for use in super markets, retail establishments, and other establishments. These bags utilize the entire space of the plastic bag, stand up right by itself and is self-supporting so that it makes loading and unloading the bag easier. 
   This heretofore not available new closure will enable such plastic bags to have many uses apparent to the user and the reader of this application. 
   This bag may be used to hold products in markets, such as, food, deli counter operations, dog food and the like as well as boxed and canned goods. While made of flexible plastic material may be made of sturdy and strong, i.e., heavy wall construction that the filled bag may be conveniently carried. It would also be extremely beneficial to provide means for automated closing the open top after the bag is filled. 
   It is the object of this present invention to close a “flat bottom” or “square bottom” gussetted bag, after being filled, at the upper edge of the bag while allowing a maximum opening for filling and discharge of the bag. 
   Another object of this present invention is to provide the bag for use for liquids, solids, semi solids, frozen and defrosted items while maintaining the integrity of the self-standing bottom plastic gussetted sack or bag. 
   It is another object to provide a “flat bottom” bag with automatic top closure having a carrying handle. The objects as well as other objects and advantages will be obvious from the following disclosures. 
   SUMMARY OF THE INVENTION 
   In my prior patents, U.S. Pat. Nos. 3,988,970, 3,916,770 and 4,230,300, I disclosed plastic bags and their manufacture in which a flat bottom has been formed. The “flat” or “square bottom” bag is formed from a tubular sleeve having gussets on each side. A long transverse seal is applied to the bottom of the tube to form a bag. An internal opening mechanism is provided to open and “square off” the bottom Two bottom seals are applied to reinforce the bottom of the bag. Further, square bottom serve to allow the bag to be neatly folded for stacking and shipping. The bags shown in these patents also have side gussetts similarly designed to allow folding and stacking for shipping. 
   According to the present invention a gussetted bag of the type shown in my earlier patents containing a tubular sleeve having an open top, a closed bottom wall, a front and back faces and a pair of opposing side walls connecting the front and back faces is improved. The side walls are formed with at least one fold creating in the side walls at least one gusset allowing the front and back faces to extend from each other. The gussets are sealed unitarily at the bottom ends of the bottom wall, sealed through and through along their top edges of the the front and back faces inwardly respective from the side wall. Then, as will be seen the “square bottom” bag takes on a triangular lengthwide shape normally biased closed at the top but easily openable for maximum full and discharge of the interior of the bag. 
   Full details of the present invention are set forth in the following disclosure and shown in the accompanying drawings. 

   
     BRIEF DESCRIPTION OF DRAWINGS 
     In the drawings: 
       FIG. 1  is a series perspective views showing the construction of a flat bottom tubular bag, 
       FIG. 2  is perspectal view of a flat bottom bag having the gusset construction of the present invention, 
       FIG. 3  is a view of the bag invention, on its side,  FIG. 2  is a view showing the discharge of goods from the interior thereof. 
   

   DESCRIPTION OF THE INVENTION 
   Seen in  FIG. 1 , a typical endless roll plastic of tubular sleeve construction  10  used to form the initial bag  12  to which the invention is applied to. In step A, a portion of the endless tubular sleeve is shaped in accordance with the afore mentioned patents, to which reference can be made as if more fully set forth. The sleeve is cut in Step B, to have a rectangle shape with a transverse cross section having a pair of opposing faces  14  and a pair of side walls  16 . Each side wall  16  is formed with at least a one longitudinal gussets  18  although two pair are preferred. The gussets  18  are folded inwardly and the tubular sleeve flattened by pressing the the opposing faces  14  in together. Then, in Step C, the plastic bag is opened and a “former” or mandrel is moved into the bag  14  so as to “square off” the bottom to make a “flat bottom”  20 . In Step D, bottom seals  22  (one on each side of the bottom) are applied to seal the bottom to the side walls  16  making the “square bottom” rigid. As seen in Step E and F, the bag is then sealed with a seam  24  from side wall to side wall at the bottom with a heat sealing mechanism making the “T” shirt bag leaving the top open ended as at  26  bag. 
   Turning to  FIGS. 2 and 3 , the present invention provides the top edge  26  with a closure seal  46  applied to limit of the length of gusset sides  18 . The reduced gussets sides  18  are made as small as as possible without interfering with the required size of the bag and integrity of the “square bottom” or “flat bottom”  20 . After the gusset sealing is completed all the gusset faces are pressed together and sealed at the top end of the bag with at least one or two band seals  30  including longitudinal seal  48  sealing the pressed gusset faces completely through the film or sheet of plastic. 
   The top edge  26  of each face may be reinforced with stay  32  of bendable material, such as a corset stay so the bag automatically closes. Also a band  34  integral with the front and rear faces  14  to extend upward longitudinal seal extends from the gussets upward therefrom an opening  36  is fashioned in the band  34  establishing a handle  38 . Below the handle, along the top of the bag itself, a zipper or other closure device  46  may be placed, so that the contents of the bag can be locked and held for shipment. 
   The number of seals  30  on each side gusset  18  can be selected as desired along with the longitudinal seal  48 . At least one diagonal seal  40  is made at the bottom end of the longitudinal seal  48  on each side of the bag. These diagonal seals  40  made at the end of the longitudinal seal  48  reinforce the longitudinal seal and enable the easy flow of goods out of the bag. (See  FIG. 3 ) 
   The block seals  30  are made near the top of the bag to insure that the bag is not torn when filling or emptying out. These block seals also allow the user a place or location to grasp the bag at time of opening, closing the bag and discharging the contents at time of unloading bags. Block seals are applied simultaneously when the long longitudinal seal and diagonal seals are made through all the side gussets. As a matter of fact, all foregoing seals ( 30 , 40 , 48 ) can be made at one time. Once the gusset seals, block seals, longitudual and diagonal seals are in place, the band and a zipper closure with cut-out handle maybe formed to the upper portion of the bag separately by sealing a portion of the flap of the zipper closure to the front and back of the new construction sealed bag. 
   If made separately, the entire upper portion of the bag containing the cut-out handle and zipper closure is heat sealed to the upper portion of lower bag. The additional block seal  50  is to prevent the zipper from opening past the gussetted sealed upper portions of the bag itself. 
   Further a small slit  42  is made in the bag at a location below the top edge closure. This will enable the easy flow of material in and out of the bag allow air to also blow out of bag. 
   As seen in detail in  FIGS. 2 &amp; 3 , all gusset members are sealed together. All gusset sides are pressed and all seals are applied including the long longitudinal seal and diagonal seal are applied at one time. The seals are made on both sides of the bag.  FIG. 2  shows the smaller gussetted sides  18  to allow for a larger opening to load and unload any material in the bag. Note the reduced gusset side size  10  is to allow for maximum opening of the bag without destroying the integrity of the gussetted “square bottom” “flat bottom” bag. 
     FIGS. 2 and 3  clearly show the small slit  42  made in the bag to allow air to escape from the bag at time of loading, as well as the zipper closure to the bag along with a cut-out handle. The block seal  50  on the zipper portion of the closure is also clearly shown. 
   As seen from the foregoing, a “flat bottom” plastic bag be constructed of any desired size and for any selected use and function. The plastic film from which the bag is constructed can be transparent or opaque to allow for identifying and merchandising material. Seen in  FIGS. 2 and 3 , a translucent film having a transparent window  44  is shown. The resultant bag has a triangular tubular shape. The “flat bottom” being larger in girth through the body of the bag, thereby allowing the bag to stand upright with the top distended to allow access and egress of material Similarly, the bag can be placed on its side as seen in  FIG. 3 . 
   Furthermore, the bag allows the addition of a handle and a locking zipper or other closure device. Thereby, the resultant bag may be used as a handbag, pocket book or satchel tote. 
   Thus the scope of the disclosure should not be seen as limiting this invention should be derived only from the appended claims.