Patent Publication Number: US-2013251290-A1

Title: Tear open bag with transmission barrier

Description:
FIELD OF THE INVENTION 
     The present disclosure generally relates to a bag adapted for holding contents, and, more particularly, to such a bag including a tear open feature that inhibits transmission of substances into and out of the bag prior to opening. 
     BACKGROUND OF THE INVENTION 
     Bags used for packaging various materials include pre-formed zones of weakness on tear lines for facilitating opening of the bags. For example, materials such as water conditioning pellets, bird seed, mulch, salt, fertilizer, and other materials may be packaged in bags having pre-formed tear lines. Conventional types of pre-formed tear lines include perforations or slits. These are openings which extend through the material of the bag, exposing contents in the interior of the bag to the outside environment. Such openings are unfavorable because contents from inside the bag can escape through the openings and contaminants such as water can infiltrate the bag through the openings. 
     SUMMARY OF THE INVENTION 
     In one aspect, the present invention is directed to a bag configured for holding contents and configured for permitting a user to dispense the contents from the bag. The bag includes a bag body including at least front and rear panels of generally flexible film. The bag body defines a volume adapted for holding the contents. The front and rear panels include respective inner surfaces which face each other and form at least part of the volume. The front and rear panels include respective outer surfaces which face away from the volume. The panels each have upper ends, lower ends, and left and right sides which together respectively form an upper end, a lower end, and left and right sides of the body. The bag body includes a zone of weakness on at least one of the front and rear panels for facilitating opening of the bag body by tearing the bag body along the zone of weakness. The zone of weakness includes an embossment structure that has a tear force that is substantially constant over the entire length of the zone of weakness. 
     In another aspect, the present invention is directed to a bag configured for holding contents and configured for permitting a user to dispense the contents from the bag. The bag includes a bag body including at least front and rear panels of generally flexible film. The bag body defines a volume adapted for holding the contents. The front and rear panels include respective inner surfaces which face each other and form at least part of the volume. The bag body includes edge margins. A zone of weakness on at least one of the front and rear panels facilitates opening of the bag body by tearing the bag body along the zone of weakness. The zone of weakness includes an embossment structure extending along a path from a first of the edge margins to a second of the edge margins. Adjacent the first edge margin, the path includes a first portion starting at said first edge margin and extending away from said second edge margin and a second portion extending from said first portion to said second edge margin. 
     In yet another aspect, the present invention is directed to a bag configured for holding contents and configured for permitting a user to dispense the contents from the bag. The bag includes a bag body including at least front and rear panels of generally flexible film. The bag body defines a volume adapted for holding the contents. The front and rear panels include respective inner surfaces which face each other and form at least part of the volume. The bag body includes a zone of weakness on at least one of the front and rear panels for facilitating opening of the bag body by tearing the bag body along the zone of weakness. The zone of weakness includes an embossment structure. The embossment structure includes a series of indentations each having a non-linear shape. 
     Other features will be in part apparent and in part pointed out hereinafter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front elevation of one embodiment of a bag of the present invention; 
         FIG. 2A  is an enlarged, fragmentary view of the bag of  FIG. 1  showing a tear line on the bag; 
         FIG. 2B  is a view similar to  FIG. 2A  but showing the bag partially torn along the tear line; 
         FIG. 3  is an enlarged view of a portion of the bag showing in closer detail indentations of the tear line; 
         FIG. 4  is a schematic fragmentary section of the bag taken in the plane including line  4 - 4  in  FIG. 3 ; 
         FIG. 5  is a front elevation of a segment of a bag of a second embodiment of the present invention, a tear line of the bag being shown; 
         FIG. 6  is a front elevation of a segment of a bag of a third embodiment of the present invention, a tear line of the bag being shown; 
         FIG. 7  is an enlarged view of a portion of the bag of  FIG. 6  showing in closer detail indentations of the tear line; 
         FIG. 8  is a front elevation of a segment of a bag of a fourth embodiment of the present invention, a tear line of the bag being shown; and 
         FIG. 9  is an enlarged view of a portion of the bag of  FIG. 8  showing in closer detail indentations of the tear line. 
     
    
    
     Corresponding reference characters indicate corresponding parts throughout the drawings. 
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , a bag of a first embodiment of the present invention is shown. The bag is generally indicated by the reference number  10 . The bag is configured for holding contents and for permitting a user to dispense the contents from the bag. For example, the bag may be used to hold contents such as water conditioning pellets, bird seed, mulch, salt, and fertilizer. The bag may be used for holding other types of contents without departing from the scope of the present invention. Desirably, the bag is closed in use to contain the contents in the bag and provides a barrier to transmission of substances into and out of the bag. However, the bag is adapted for being easily opened so a user can dispense the contents from the bag by, for example, pouring or scooping the contents from the bag. 
     The bag includes a body defining a volume  12  ( FIG. 4 ) adapted for holding the contents. The bag body includes front and rear panels  14 ,  16  of generally flexible film. The front and rear panels  14 ,  16  ( FIGS. 2B and 4 ) include respective inner surfaces that face each other and form at least part of the volume  12  between the front and rear panels. The front and rear panels  14 ,  16  include respective outer surfaces that face away from the volume  12  and form outer surfaces of the bag  10 . The panels  14 ,  16  each have upper ends, lower ends, and left and right sides which together respectively form an upper end, a lower end, and left and right sides, of the bag  10 . Various suitable materials may be used without departing from the scope of the present invention. For example, the film may be a laminated material or include a multi-layer material. 
     In the illustrated embodiment, the generally flexible film forming the panels  14 ,  16  is manufactured as a tube having opposite open ends. The front and rear panels are front and rear portions of the tube. The flexible film material extends continuously between the side margins of the front and rear panels except at the upper and lower ends of the bag  10  where the front panel is sealed to the rear panel defining upper and lower seal seams  20  to close the open ends of the tube. In other words, the bag  10  includes seal seams  20  traversing the upper and lower edge margins of the bag  10 . The bag  10  has a skirt  26  at the upper edge margin of the bag and a skirt  26  at the lower edge margin of the bag. The skirts  26  are formed by the free ends of the panels  14 ,  16  which are outboard from the seal seams  20 . 
     It will be understood that at certain stages during production, such as before the bag  10  is filled with the contents, the bag may not have a seal seam  20  at the upper and/or lower edge margin. Bags may have other constructions without departing from the scope of the present invention. For example, the front and rear panels  14 ,  16  may be formed as separate sheets of material which are sealed together about their peripheral edge margins to form the volume  12  between the sheets. Moreover, the front and rear panels  14 ,  16  need not be connected directly to each other. For example, other structure such as additional panels of generally flexible film (e.g., a gusset) may extend between the front and rear panels  14 ,  16 . 
     The bag  10  includes features which facilitate opening of the bag for dispensing contents from the bag. In particular, as shown in  FIG. 1 , the bag  10  includes a tear line (broadly, “zone of weakness”), generally indicated by the reference number  30 . The tear line  30  facilitates opening of the bag  10  by tearing the bag along the tear line. The tear line  30  is shown in closer detail in  FIG. 2A . In general, the tear line  30  includes a notch  32  formed in the upper edge margin of the bag, a slit  34  extending downward from a lower end of the notch, and an embossment structure  36  extending along the bag body. The notch  32  and slit  34  are generally aligned with an upper end of the embossment structure  36 . The notch  32  is provided to facilitate finding the tear line on the perimeter of the bag  10  and start the tear. The slit  34  is provided to initiate tearing through the seal seam  20 . The embossment structure  36  is provided for facilitating tearing of the bag body in a controlled to open the bag  10  easily and accurately. 
       FIG. 2B  illustrates the tear line  30  in a partially torn configuration. Tearing the bag  10  along the tear line  30  forms an opening  38  in the bag from which the contents may be dispensed. In the illustrated embodiment, the tear line  30  is positioned for tearing at a corner of the bag  10  and thus for forming the dispensing opening  40  at the corner of the bag. Zones of weakness having other positions, arrangements, and orientations may be used without departing from the scope of the present invention. 
     The notch  32  provides a user with a clear visual and tactile indicator of where it is suggested to begin tearing along the tear line  30 . In the illustrated embodiment, the notch  32  is formed in the upper skirt  26 . Desirably, the notch  32  is shaped and sized to be visually distinct from adjacent portions of the bag  10 . For example, the notch  32  is large enough and is shaped differently than waves, ruffles, indentations, or other structure on the skirt  26 . In the illustrated embodiment, the notch  32  defines an opening having the shape of an irregular pentagon. The notch  32  has opposite generally parallel sides connected to a lower portion which forms a point leading into the slit  34 . 
     The slit  34  extends downward from the notch  32  toward an upper end of the embossment structure  36  and assists the user in beginning to tear the embossment structure. In the illustrated embodiment, the slit  34  extends entirely across the upper seal seam  20 . Accordingly, the user does not need to tear across the seal seam  20  when tearing the tear line  30 . The slit  34  extending across the seal seam  20  may reduce the initial tear force by about 25 to 45 percent, and keeps the tear force more consistent of its full length. If the slit  34  extends across and beyond the seal seam  20  the slit may create a slight opening in the bag body. Even in this instance, there is no significant compromise to the transmission barrier at the tear line  30 . Other slit configurations may be used without departing from the scope of the present invention. For example, the slit  34  may stop short of the seal seam  20  or may extend only partially across the seal seam. 
     The embossment structure  36  includes a series of indentations  40 . The indentations  40  are arranged one after another along a path. The embossment structure  36  may extend partially or entirely across a portion of the bag  10  or from one edge margin to another. In the illustrated embodiment, the embossment structure  36  traverses a corner of the bag  10 , from the upper edge margin to the right side edge margin. The indentations  40  extend along a curvilinear path. Other arrangements, such as indentations extending along other paths or along paths having other shapes (e.g., a rectilinear path) may be used without departing from the scope of the present invention. 
     A portion of the embossment structure  36  is shown in closer detail in  FIG. 3 . In the illustrated embodiment, the indentations  40  of the embossment structure are deformations at which the generally flexible film is stretched beyond a yield point of the flexible film but not stretched beyond a break point of the flexible film. The result is the film at the deformations  40  is susceptible to tearing by application of less manual force than would be required to tear the bag body if not deformed. As used herein, the term yield point refers to the point at which irreversible plastic deformation occurs. Before reaching the yield point, the film behaves elastically, such that it resumes its original local state (e.g., generally planar) when the applied forces are removed. As used herein, the term break point refers to the point at which the film tears or an opening is formed in the film which extends entirely through the film. Desirably, before the tear line  30  is torn, the embossment structure  36  is free from any opening passing through the tear line so that the function of the bag to bar transmission of substances into or out of the bag is maintained at the tear line. 
     Referring to  FIG. 3 , each of the indentations  40  has a front end  40 A and a rear end  40 B. The rear end  40 B of each indentation  40  is positioned adjacent the front end  40 A of an immediately previous indentation in the series. The front end  40 A of each indentation  40  is positioned adjacent the rear end  40 B of an immediately subsequent indentation in the series. Each of the indentations  40  has a length L extending along the path formed by the indentations and a width W extending generally perpendicular to the path formed by the indentations. In the illustrated embodiment, the embossment structure  36  also includes connecting segments  50 . The indentations  40  are spaced from one another (e.g., about 0.06 inches or 1.52 mm) and connected to one another by the connecting segments  50 , which have a generally linear shape and have a length equal to the space between adjacent indentations. More specifically, the connecting segments  50  extend between and connect the front and rear ends  40 A,  40 B of adjacent indentations  40 . In the illustrated embodiment, the connecting segments  50  are deformations which are formed at the same time as the indentations  40 . The connecting segments  50  may be omitted or have other shapes without departing from the scope of the present invention. 
     The indentations  40  each have a non-linear shape; meaning that the indentations are not very thin rectangles such as would be formed by a knife edge type tool. The non-linear shape of the indentations  40  improves the consistency of force required to tear along the embossment structure  36 . Each indentation  40  includes an intermediate portion between its front and rear ends  40 A,  40 B. The width of each indentation  40  at its front and rear ends  40 A,  40 B is less than the width of the indentation at its intermediate portion. In the illustrated embodiment, the front and rear ends  40 A,  40 B of each indentation  40  are pointed. The tear line  30  includes a tearing path formed by the indentations  40  along which the tear line is most prone to tearing. In the illustrated embodiment, the tearing path is arcuate. Each indentation  40  includes first and second sides  40 C,  40 D extending between its front and rear ends  40 A,  40 B along the length of the indentation. The first side  40 C is positioned in register with and forms a segment of the tearing path. The first sides  40 C of the indentations  40  are aligned along the tearing path to form the tearing path. The pointed front and rear ends  40 A,  40 B of the indentations are positioned on the tearing path. The pointed front and rear ends  40 A,  40 B of adjacent indentations are connected to each other by the generally linear connecting segments  50 , which are also positioned in register with and form part of the tearing path. In the illustrated embodiment, the indentations  40  include a generally semi-circular shape. Other sizes and shapes of indentations may be used (including in some embodiments linear shaped indentations) without departing from the scope of the present invention. 
     The notch  32 , slit  34 , and embossment structure  36  may be formed on the bag  10  using the same or separate tools. For example, the embossment structure  36  may be formed on bags in a continuous fashion using a rotary die unit. Such a die unit may include flexible or rigid dies or rollers between which the film is moved. At least one of the rollers is a male roller including a raised pattern which impresses a corresponding embossed pattern on the film. Optionally, the other roller may be a female roller including an indented pattern corresponding to the raised pattern on the other roller for receiving the raised pattern and the indentations as they are formed in the film. If the front and rear panels  14 ,  16  are already arranged in opposing relationship, the embossed pattern is applied in register to both the front and rear panels. Such a configuration is illustrated in the schematic partial section of  FIG. 4 . The embossment structure  36  may be formed in the front and rear panels  14 ,  16  at the same or different times without departing from the scope of the present invention. The rollers may or may not be heated to heat the film as the indentations are formed. Other methods of forming the indentations may be used without departing from the scope of the present invention. For example, the embossment structure  36  may be formed on bags in a batch process, using, for example, stamps which are pressed into bags as they are momentarily stationary in register with the stamps. 
     In the illustrated embodiment, the tear line  30  is provided on both the front and rear panels  14 ,  16  of the bag. In other words, the notch  32 , slit  34 , and embossment structure  36  are formed in both the front and rear panels  14 ,  16 . The tear line  30  or portions of the tear line may be formed in only one of the front and rear panels  14 ,  16  without departing from the scope of the present invention. 
     As is now apparent, the bag  10  provides several advantages. In use, the notch  32  makes the tear line  30  clearly identifiable, and the slit  34  extending from the notch facilitates easy initiation of tearing through the seal seam  20 . The embossment structure  36  facilitates tearing of the bag  10  along a predetermined tearing path to form a desired opening in the bag  10 . The embossment structure  36  is free from any openings extending through the film forming the bag  10  at the embossment structure such that contents inside the bag are less likely to leak from the bag, and moisture and contaminants are less likely to infiltrate the bag through the tear line  30 . Accordingly, contents in the bag  10  are less likely to escape and form a sticky, dusty, or otherwise undesirable residue or coating on the exterior surface of the bag. Contents having relatively smaller particle size (e.g., finer grain salt) can be contained in the bag  10  without risk of the contents leaking out of the tear line  30 . In addition, contents in the bag  10  are less likely to be contaminated, such as by water entering the bag through the tear line  30 . 
     Desirably, the force required to tear along the tear line  30  to open the bag  10  (i.e., the “tear force”) is as small as possible, but the tear line is strong enough to resist opening in response to some forces not intended to tear the tear line. For example, the tear force may be between about 2 and 4 pounds. This makes it easy for the user to open the bag  10 . In some embodiments, embossment structure  36  is configured to have such a minimal tear force while being strong enough to resist inadvertent opening such as by bursting or rupturing if the bag impacts the ground after being dropped. A test used to quantify the ability of a bag to withstand inadvertent opening of the bag is referred to as a Drop Test. The Drop Test as used herein means dropping a closed bag containing contents (e.g., granular salt) which substantially fill the internal volume of the bag from a height of four feet such that the bag falls freely and strikes and comes to rest against an impact surface (e.g., a concrete floor) without the tear line partially or completely opening, tearing, or bursting (i.e., the tear line remains unbroken). Pursuant to the Drop Test, the bag is dropped six separate times so that the bag strikes the impact surface one time on each of the top and bottom and front, rear, left, and right sides of the bag. Bags according to the present invention (e.g., including an embossment structure) have been constructed and tested pursuant to the Drop Test. The Drop Test is generally according to FDA B-12. The embossment structure had a tear force of between about 2 and 4 pounds, and the bags passed the Drop Test. 
     Referring to  FIG. 5 , a second embodiment of a bag of the present invention is generally designated by the reference number  110 . The bag is identical to the bag  10  except as described. Corresponding parts are indicated by corresponding reference numbers. For example, the bag  110  has a zone of weakness or tear line  130  including an embossment structure  136 . The embossment structure  136  includes a series of non-linear indentations  140  which are spaced from one another. The indentations  140  are connected to each other by connecting segments  150  each having a generally linear shape. The connecting segments  150  may be omitted or have other shapes without departing from the scope of the present invention. 
     In this embodiment, the embossment structure  136  is constructed to tear in response to a tear force that is substantially constant over the entire length of the embossment structure, notwithstanding the change in direction of the embossment structure from extending generally lengthwise of the bag  110  (e.g., a “machine direction” of the bag) to generally widthwise of the bag (e.g., a “cross-machine direction” of the bag). For example, the tear force may be about 4 pounds or less. As shown in  FIG. 5 , the embossment structure  136  includes indentations  140  which are spaced different distances from each other. In other words, the density of the indentations  140  along the series of indentations is different at different portions of the series of indentations. In the illustrated embodiment, the indentations  140  extend along a path which includes a first portion that is oriented in predominantly an upper end to lower end direction of the bag body and a second portion that is oriented predominantly in a left side to right side direction of the bag body. The spacing between adjacent indentations  140  (or density of the indentations) is greater when the path is oriented in the predominantly upper end to lower end direction than when the path is oriented in the predominantly left side to right side direction. For example, the spacing between adjacent indentations  140  (or density of the indentations) in the first path portion oriented in the predominantly upper end to lower end direction may be about three times greater than the spacing of adjacent indentations (or density of the indentations) in the second path portion that is located in the predominantly left side to right side direction. The decrease in spacing between adjacent indentations  140  at the second portion that is oriented in the predominantly left side to right side direction of the bag  110  decreases the tear force at that second portion to make it more consistent with the tear force of the first portion that is oriented in the predominantly upper end to lower end direction of the bag. In general, the variation in spacing between the indentations may depend upon the composition of the material of the bag, and orientation of strength of the bag. There may be more than one variation in the spacing and the ratio of greatest to smallest spacing can be other than three times as described above. 
     In the illustrated embodiment, the series of indentations  140  include three separate regions  160 A- 160 C along the path of indentations. The first region of indentations  160 A extends along the portion of the path that is oriented in the predominantly upper end to lower end direction of the bag body. The third region of indentations  160 C extends along the portion of the path that is oriented in the predominantly left side to right side direction. The second region  160 B extends along an intermediate portion of the path between the first and second regions  160 A,  160 C. The indentations  140  in the first, second, and third regions  160 A- 160 C are spaced apart from one another different distances (i.e., the connecting segments  150  have different lengths in each of the zones). For example, the spacing between adjacent indentations  140  in the first region  160 A may be about 0.20 inches (5.1 mm), the spacing between adjacent indentations in the second region  160 B may be about 0.10 inches (2.5 mm), and the spacing between adjacent indentations in the third region  140 C may be about 0.05 inches (1.3 mm). In other words, the density of indentations  140  in the first region  160 A is on the order of three to four times greater than the density of the indentations in the third region  160 C. Other spacings or densities may be used without departing from the scope of the present invention. For example, there may be two regions of different indentation spacings, having for example spacings of 0.06 inches (1.6 mm) and 0.19 inches (4.8 mm), respectively. The spacing or density of the indentations  140  may more gradually change or change continuously along substantially all or a portion of the path of indentations. The ration of spacing between the largest and smallest spacing may be other than described within the scope of the present invention. 
     Referring to  FIGS. 6 and 7 , a third embodiment of a bag of the present invention is generally designated by the reference number  210 . The bag is identical to the bag  10  except as described. Corresponding parts are indicated by corresponding reference numbers. For example, the bag  210  has a zone of weakness or tear line  230  including an embossment structure  236 . The embossment structure  236  includes a series of non-linear indentations  240  which are spaced from one another. In this embodiment, there are no connecting segments (e.g., like segments  50  of the first embodiment) which connect adjacent indentations. The indentations  240  have pointed front and rear ends  240 A,  240 B. The front and rear ends  240 A,  240 B of adjacent indentations  240  are not connected to each other. 
     Referring to  FIGS. 8 and 9 , a fourth embodiment of a bag of the present invention is generally designated by the reference number  310 . The bag is identical to the bag  10  except as described. Corresponding parts are indicated by corresponding reference numbers. For example, the bag  310  has a zone of weakness or tear line  330  including an embossment structure  336 . The embossment structure  336  includes a series of non-linear indentations  340  which are spaced from one another. In this embodiment, the indentations  340  each have a generally trapezoidal shape. Referring to  FIG. 9 , each indentation  340  has pointed front and rear ends  340 A,  340 B. The indentations  340  are not connected to each other by connecting segments. For example, adjacent indentations  340  may be spaced from each other from about 0.02 to 0.30 inches (0.51 mm to 7.6 mm). In the illustrated embodiment, adjacent indentations are spaced from each other about 0.06 inches (1.5 mm). The indentations  340  have a long side  340 C and a short side  340 D. The long sides  340 C of the indentations  340  are positioned in register with each other and form segments of the tearing path along which the tear line  330  is most prone to tearing. 
     Referring again to  FIG. 8 , the embossment structure  336  extends along an arcuate path which is different than the paths of embossment structures described above. The embossment structure  336  extends along a path from the upper edge margin of the bag  310  to the right side margin of the bag. Adjacent the upper edge margin, the path includes a first portion  370 A starting at the upper edge margin and extending away from the right side edge margin and a second portion  370 B extending from the first portion to the right side edge margin. As a result, the center of the arc formed by the embossment structure  336  extends farther into the bag than a conventionally shaped perforation structure that extend parallel to the right side margin. The path having this configuration provides the opening formed by tearing the embossment structure  336  with a large mouth. More specifically, the path portion  370 A adjacent the upper edge margin which extends away from the right side edge margin provides the resulting opening with a larger mouth compared to the opening if the path portion adjacent the upper edge margin did not extend away from the right side edge margin. For example, the mouth may be over ten percent larger than conventionally formed mouths. The wider opening makes it easier to pour contents from the bag  310 . 
     Having described the invention in detail, it will be apparent that modifications and variations are possible without departing from the scope of the invention defined in the appended claims. 
     As various changes could be made in the above constructions and methods without departing from the scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.