Patent CA-2008971-A1 (CA)
Title: Serial dispensing bags which automatically open
Inventor: DEMATTEIS ROBERT B
IPC: B65D33/00
Filed: 1990-01-31
Abstract: SERIAL DISPENSING BAGS WHICH OPEN AUTOMATICALLY               ABSTRACT OF THE DISCLOSURE A unit of thermoplastic grocery bags are manufactured, assembled, prepared for use and dispensed in such a way that upon loading and dispensing the first bag of a serialized unit of bags, a subsequent bag in the unit is automatically opened. The bags are manufactured through use of a co-extrusion process wherein a bag has different characteristics for both the surfaces of the interior and the exterior of the bag.  The bag exhibits a "slipperiness" between the interior surfaces of the bag.   The bag  also exhibits  a  "stickiness"  on the exterior surfaces, allowing the bags to have a tendency to cling to one another.  Co-extruded bags will exhibit these characteristics if a high density resin is used for the interior surface and a low density resin is used for the exterior surface.  The reader will understand that it is the character-istics of slipperiness and stickiness which are important to the present invention, and not merely the use of specified material; this is because the natural characteristics of resins may be altered through the use of "slip" and "anti-block," as is known in the art, to increase or decrease slipperiness or stickiness. Therefore,  medium density resins may be used in the interior layer if they attain the requisite slipperiness. Applicant refers to a coefficient of friction existing between portions of like layers, i.e., an inside layer portion contacting another inside layer portion, or an outside layer portion contacting another outside layer portion as a mutual coefficient of friction.  Therefore, the mutual coefficient of friction exhibited by the inside layers is less than the mutual coefficient of friction of the outside layers.            The grocery bags are also provided with apertures through which supporting rods will ultimately be inserted to support the finally produced bag bundle prior to dispensing.        In a preferred embodiment, the apertures which have  been  created  are  positioned  relative  to  the supporting rod so that the dog-ear flap contacts the top surface.  In a bundle of serialized bags, the flaps will all be oriented in the same direction.  When the rod is inserted through the apertures, the flaps will be forced outward and upward,  such that they tend to be in a horizontal plane.  The bottom most flap of the rear wall of  the  last  bag will  contact  the  top  of the  rod. Successive flaps will overlie the immediately subsequent flaps.   In this  fashion,  the  flaps all  overlie one another on the top of the rod with the first flap of the first bag being the top most flap.  The natural depending weight of the bags, as transferred to the handles, rests on the layers of flaps, increasing the frictional forces existing between the layers.   These flaps provide an entraining means  between  the  individual  bags  to  be dispensed.  It is another preferred embodiment to orient the dog-ear flaps in the handles so that a normal force existing between the flaps and a supporting rod when threaded through an aperture may be increased during removal  of  bags  to  provide sufficient  self-opening forces.  It is understood that flaps could be oriented under the supporting rod, or at the side thereof, if a bag is to be generally urged up at it is removed.        It is one embodiment of the present invention to increase the self-opening force of the entraining means by blunting a blade which creates the dog-ear flaps. This increases the clinging effect of the outer layers.        The bags are also designed to reduce an automatic opening resisting force between a front tab of the bag and the wicket.  A tab is created during manufacturing on the front and on the back of each bag and will act as a means for retaining the bags into a bundle.  These tabs are fused together to form a wicket which keeps the hags in a unit having a series of bags overlying one another. The tab on the front of any given bag will resist the automatic opening of the bag as the front wall is biased to an open position.  In a preferred embodiment, rollers are inserted in the interior of the tube of plastic as it is being processed, and a cutting blade slices what will become the front wall at the position immediately below the  position where  the  front  tab will  be  created. Therefore,  once the tab is created and fused to the wicket, the front tab will not be attached to the bag body and will serve no function.  Thus, the bag will be attached to the wicket solely through the use of the back tab.   This prevents the front tab from resisting the self-opening forces.        Another preferred embodiment is to control the cut-out operation which creates the tabs.  The tab is narrowed at a critical dimension and provided with an initial cut interior to and horizontal with respect to the tab.  Creating the tab in this fashion utilizes the natural tendency the bag has to straight line tear and allows the tabs to be easily severed from the wicket while supporting the bay unit to a dispensing rack.        In operation,  the bags which are created are serialized by successively stacking one on another.  The outside surfaces of the bags are relatively sticky with respect to one another, and the insides of the bags slide relatively easily with respect to one another.  Handles apertures, and tabs for the bags are created during a cut-out operation, and the bags are fused together at the wicket to produce the dispensing units.  The apertures create dog ears which will key the bags together when mounted  on a  dispensing rack.   The bags  are  keyed together by a successive series of overlying flaps loaded by natural  depending weight  of the bag unit.   The dispensing  rack  has  two  horizontal  supporting  rods extending parallel to each other in the direction in which the serialized bags are to be dispensed.   The supporting rods are inserted through the apertures such that the dog ears overlie the supporting rod and the natural depending weight of the bags and the handles increase  the  frictional  forces  existing between  the overlying layers of the dog ears.        A first  front  bag  is  initially  opened  by releasing the front tab from the wicket, if necessary, and pulling the front wall from the back wall.  As the interior of the bag surfaces  are relatively slippery, the walls of the bags open relatively easily and a top flap and a subsequent flap slide relatively easily.  opening the first front bag causes the first flap to draw forward sliding off the top of the layers of overlying flaps.  As the first two flaps slide relatively easily with respect to one another, the second flap does not move.   The second flap is attached to the rear wall of the first bag, therefore the rear wall does not move.   The tab attaching the rear wall to the wicket holds the rear wall in its original position.  The frictional force between the second flap and a third flap (the front flap on a second bag) also tends to retain the rear wall of the second bag.  As the front wall of the first bag is urged forward and the rear wall is relatively stationary, the first front bag is opened.        After the first  front bag  is  loaded,  it  is dispensed from the rack by sliding it off the supporting rods.  To do this, the back tab is severed, allowing the first front bag to be removed.  When it is being removed, the frictional forces between the outside back wall of the first front bag and the front wall of the first subsequent  bag  urge  the  front  wall  of  the  first subsequent bag forward. Additionally, the frictional forces on the dog ears tend to open the front wall of the first subsequent bag as well.  the second flap, being a part of the rear wall of the first bag, is slid off the layers of overlying flaps and off the rod as the first bag is removed.  The second flap immediately overlies the third flap attached to the front wall of the second bag.   As the second flap is being urged off the successive layers of flaps,  the higher frictional forces existing between the two flaps urge the third flap forward.  The urging forward of the third slap directly urges the front wall of the second bag forward.  Therefore, the second bag is urged open. The forces mentioned above which tended to retain the rear wall of the first bag prior to loading are identical to the forces retaining the rear wall of the second bag.        As the front wall of the second bag is urged forward and the rear wall is retained in its original position,  the second bag is opened.   The two forces urging the front wall of the second bag forward are sufficient to overwhelm the retaining force of the tab attached to the front wall of the second bag.        Therefore, as the first front bag is removed, the first subsequent bag is opened as was the first front bag and becomes the second front bag which will open the second  subsequent bag when the  second  front bag  is removed in due course,  et cetera.   In this fashion, serial dispensing of the bags is accomplished wherein subsequent  bags  are  opened  automatically  as  an immediately preceding bag is removed.