Abstract:
The disclosure relates to a large package, typically with woven polypropylene walls, including an easy-open strip with a pre-activated peel seal. The easy-open strip achieves a high burst strength by configuring the pre-activated peel seal in shear mode in response to internal (product side) forces while achieving a low consumer opening force by configuring the peel seal in response to external (consumer side) forces.

Description:
[0001]    This application claims priority under 35 U.S.C. §119(e) of U.S. provisional application Ser. No. 61/152,571 filed Feb. 13, 2009, the disclosure of which is hereby incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Disclosure 
         [0003]    The present disclosure pertains to a package or bag, particularly a large capacity easy-open package or bag with woven polypropylene walls wherein high burst capability and easy consumer opening capability are maintained. 
         [0004]    2. Description of the Prior Art 
         [0005]    Commercial packages or bags must have high burst characteristics to survive the distribution channel. This is particularly an issue for larger capacity packages or bags. A representative prior art large capacity reclosable package or bag having high burst capability and easy consumer opening is disclosed in commonly-assigned U.S. Published Patent Application No. 2008/0050052 entitled “High Burst Zipper Assembly For Large Reclosable Packages”, published on Feb. 28, 2008 with Anzini et al. as inventors. 
         [0006]    Another way to maintain an easy opening feature is to use Zipper No. 584-001, available from Zip-Pak in Orangeburg, N.Y. This zipper includes a pre-activated peel-seal which is placed into a peel configuration for easy opening and in shear configuration during filling and drop testing. 
         [0007]    Woven polypropylene bags are tough and robust as required by the demands of the distribution channel, but many typically are sewn and may require significant force to open, or require a tool, such as a knife or scissors to open the bag. The use of a tool is typically not a problem in industrial applications, but can be problematic in retail or consumer applications. 
       OBJECTS AND SUMMARY OF THE DISCLOSURE 
       [0008]    It is therefore an object of the present disclosure to provide an easy open, high burst package, particularly an easy-open package, which may include woven polypropylene walls. 
         [0009]    This and other objects are obtained by providing an easy-open package or bag, preferably including woven polypropylene walls, with an easy-open strip which incorporates a pre-activated peel seal into the flange design creating a peel configuration for easy opening and a shear configuration for high burst strength during filling and drop testing. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    Further objects and advantages of the invention will become apparent from the following description and from the accompanying drawings, wherein: 
           [0011]      FIG. 1  is a perspective view, partially in phantom, of the package or bag of the present disclosure. 
           [0012]      FIG. 2  is a cross-sectional view of the easy-open strip of the present disclosure with internal forces applied thereby putting the peel seal into shear mode. 
           [0013]      FIG. 3  is a cross-sectional view of the easy-open of the present disclosure with external user opening forces applied thereby putting the peel seal into peel mode. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0014]    Referring now to the drawings in detail wherein like numerals indicate like elements, one sees that  FIG. 1  is a simple drawing of a large package or bag  10 . Package or bag  10  includes front and rear walls  12 ,  14 , respectively, which are typically made from woven polypropylene, and sealed together along first and second side seals  16 ,  18  However, those skilled in the art may see a range of equivalent materials after review of the present disclosure, such as but not limited to, multilayer laminates incorporating scrim, netting, gauze or woven materials, made from claf (heat-sealable, cross-laminated non-woven open-mesh fabric), or strong resin materials such as nylon, polypropylene, high density polyethylene, polystyrene or other similar substrates. The package or bag  10  is typically considered to be “large” within the common usage of the industry in that is designed to be filled with 14-50 pounds of product, although different capacities may be used. The product may include, but is not limited to, charcoal, pet food, livestock food, grain, seeds, sand, fertilizer, etc. 
         [0015]    Package or bag  10  is illustrated with upper and lower easy-open strips  20 ,  20 ′, on the top and bottom ends, respectively, extending the entire width of the front and rear walls  12 ,  14  between first and second side seals  16 ,  18 . However, some applications may require only the upper easy-open strip  20 , with the lower easy-open strip  20 ′ replaced by a traditional sewn bottom.  FIG. 1  shows the upper and lower easy-open strips  20 ,  20 ′ including thumb tabs  22 ,  22 ′. 
         [0016]      FIGS. 2 and 3  show the structure of easy-open strip  20 , which applies equally to easy-open strip  20 ′. As shown in  FIG. 2 , prior to the opening of easy-open strip  20 , the front and rear walls  12 ,  14  meet at junction  24 . Junction  24  typically includes a line of weakness such as a perforated line, laser scoring, or slit thereby adding to the strength of the easy-open strip  20  in the closed configuration, but allowing simplified initial opening or breaking by the user. Grippable thumb tabs  22  may be provided on one or both sides of junction  24  to assist in the initial opening or breaking by the user. Moreover, the line of weakness could extend partially or fully across the front and rear walls  12 ,  14  and could likewise extend into the side seals  16 ,  18 . 
         [0017]    First flange  30  is provided with first and second ends  32 ,  34 . First flange  30  is typically made from polyethylene, but is not limited thereto. First and second ends  32 ,  34  of first flange  30  are sealed to rear wall  14  (front and rear walls  12 ,  14  may be considered to be interchangeable with respect to the orientation of easy-open strip  20 ) by first and second hard seals  36 ,  38 . Those skilled in the art will recognize, after review of the present disclosure, that different materials used for front and rear walls  12 ,  14  may allow or require different methods for formation of first and second hard seals  12 ,  14 , such as ultrasonic sealing. In the case of woven polypropylene front and rear walls  12 ,  14 , first and second hard seals  36 ,  38  are typically formed by the adhesive methods taught in U.S. Published Application 2009/0297817 entitled “Sealant for Polyethylene Zipper for Polypropylene Film Substrate” published on Dec. 3, 2009 naming Olajide et al. as inventors. These adhesive methods include an evenly distributed polypropylene/polyethylene plastomer mix and further include extruding a coextruded blend of metallocene polyethylene/polypropylene plastomers onto the polyethylene zipper component, then applying a hot melt amorphous polyolefin (APAO) thereover and joining the polypropylene wall or substrate to the hot melt amorphous polyolefin. 
         [0018]    Second flange  42  is provided with first and second ends  44 ,  46 . Second flange  42  is typically made from polyethylene, but is not limited thereto. First end  44  of second flange  42  is attached to first flange  30  between first and second hard seals  36  and  38  by a releasable connection  48 . Releasable connection  48  is typically, but not limited to, a pre-activated peel seal  48  and is illustrated as such. However, peel seal  48  may be replaced with many different kinds and compositions of zipper profiles including press-to-close, double zipper profiles, zipper profiles with a slider, hook and loop, mushroom fields, all male profiles, all female profiles, etc. Second end  46  of second flange  42  is attached to front wall  12  by third hard seal  50  which is typically formed similar to first and second hard seals  36 ,  38  as described above. 
         [0019]    As shown in  FIG. 2 , when internal (product side) forces act on the closed easy-open strip  20 , the pre-activated peel seal  48  is put into shear mode, which requires a much larger opening force than peel mode. The increased strength of the peel seal  48 , along with the strength added by the intact junction  24  provide for a relatively strong configuration. 
         [0020]    On the other hand, as shown in  FIG. 3 , when the junction  24  has been broken by the consumer and external (consumer side) forces are applied to the easy-open strip  20  (such as by grasping one of the tabs  22  and the edge of front wall  12 ), the peel seal  48  is in peel mode, which requires a much lower opening force than shear mode. Additionally, the strength which was otherwise added by junction  24  has been eliminated in  FIG. 3 . This provides the consumer with easy access to the contents of package or bag  10 . 
         [0021]    First and second flanges  30 ,  42  could alternatively be made of polypropylene, but the hard seals  36 ,  38 ,  50  would still be formed from glue as heat sealing to the highly oriented woven tapes of front and rear walls  12 ,  14  is a narrow latitude (10 degrees Centigrade, at best), without film distortion and resultant poor cosmetic quality. Those skilled in the art will recognize, after review of this disclosure that some applications could have first and second flanges  30 ,  42  formed from such materials as high density polyethylene, medium density polyethylene, low density polyethylene, linear low density polyethylene, polypropylene, cyclic olefin copolymers, ultra low density polyethylene, very low density polyethylene, elastomers, plastomers, metallocene linear low density polyethylene and metallocene polypropylene, but not limited thereto. It is noted that such terms as “high density”, “medium density” and “low density” as used above are terms of art which would be understood by those skilled in the art. 
         [0022]    Thus the several aforementioned objects and advantages are most effectively attained. Although preferred embodiments of the invention have been disclosed and described in detail herein, it should be understood that this invention is in no sense limited thereby and its scope is to be determined by that of the appended claims.