Patent Abstract:
A fastener for a reclosable container is constructed of a biodegradable material. The fastener includes two tracks that interlock to close the container. The fastener may include flanges to prevent damage to other portions of the container. The material may contain a small percentage of starch to permit the fastener to biodegrade within a few years after the container has been discarded. The remainder of the container may also be constructed of a biodegradable material.

Full Description:
TECHNICAL FIELD  
       [0001]     The present invention relates to biodegradable and degradable containers and in particular to reclosable fasteners to seal containers made from these materials.  
       BACKGROUND OF THE INVENTION  
       [0002]     Containers such as so called plastic bags have long been a source of non-degradable materials found in landfills and littered in the environment. Biodegradable materials have been developed for the plastics, usually polyethylene and polypropylene, to allow the bags to breakdown. The film for these bags may be cast or blown during production. Typically, a biodegradable material will breakdown in a manner of years or months, depending upon the constituents of the material.  
         [0003]     Reclosable containers such as bags have been developed to generally permit a user to open and reseal the container. Typically, these reclosable containers incorporate a fastener adjacent a container end to releasably affix opposing walls of the container, thereby selectively forming a bag opening defined by the releasable fastener. For containers where an seal is desired, the fastener may include a pair of longitudinal tracks that bindingly engage where each track is secured to a wall of the container. Differing profiles for the longitudinal tracks may be selected based upon factors such as force required to open/close,  
         [0004]     One disadvantage of known biodegradable containers in the form of bag-like structures is that the entire container is actually not biodegradable. In particular, a biodegradable reclosable fastener has not been in use. What is needed, therefore, is a fastener for a container that is bag-like, which is biodegradable, easily manufactured, and readily adhered to at least a part of the container.  
       SUMMARY OF THE INVENTION  
       [0005]     An embodiment of the present invention provides a biodegradable fastener for a container, the fastener including a first track and a second track. The first track has a first base and a joining surface extending therefrom. The second track has a second base and an engaging surface extending therefrom. The joining surface and the engaging surface matingly engage to releasably fasten the first base to the second base.  
         [0006]     Another embodiment of the present invention provides a container that includes a film enclosure wall and a fastener. The fastener is coupled to at least part of the wall. The fastener selectively encloses at least a portion of the container. At least a portion of the fastener is biodegradable.  
         [0007]     Yet another embodiment of the present invention provides a method of manufacturing a fastener. The method includes forming a first track having a first base and a joining surface extending therefrom and forming a second track having a second base and a complementary engaging surface extending therefrom. The joining surface and the engaging surface matingly engage to releasably fasten the first base to the second base. At least one of the first track and the second track is biodegradable. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]     The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:  
         [0009]      FIG. 1  is a perspective view of a container in accordance with an embodiment of the present invention.  
         [0010]      FIG. 2  is a partial sectional view of the container of  FIG. 1 , taken along line  2 - 2  of  FIG. 1 .  
         [0011]      FIG. 3  is a partial sectional view of the container of  FIG. 1 , taken along line  3 - 3  of  FIG. 1 , illustrating a fastener with the remainder of the container removed for clarity.  
         [0012]      FIG. 4  is a sectional view of an alternative embodiment of a fastener in accordance with the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0013]     Referring to  FIGS. 1 and 2 , an embodiment of a container  20  is illustrated. Container  20  includes a first wall  22  and a second wall  24 . The first wall  22  and the second wall  24  are connected by a first seam  26 , a second seam  28 , a third seam  30 , and a releasable fastener  40 , possibly in the form of a zipper. First wall  22  includes a first end  32  and second wall  24  includes a second end  34 .  
         [0014]     Any one of seams  26 ,  28 ,  30  may be a fold of a continuous material of walls  22 ,  24  and not a joining of the materials of walls  22 ,  24 . Container  20  is preferably sealed generally air-tight by seams  26 ,  28 ,  30  and fastener  40 , as described in greater detail herein, although container  20  need not be an air tight container. As best seen in  FIG. 1 , fastener  40  includes a first end  42  and a second end  44 . In two of the possible embodiments fastener  40  is affixed to at least a part of walls  22 ,  24  by heat fusing or adhesive.  
         [0015]     As best seen in  FIG. 3 , a disclosed fastener  40  includes a first track  50  and a second track  52 . The first track  50  includes a first base  54  with a first pair of interlocking ribs  58  extending therefrom. The second track  52  includes a second base  60  with a second pair of interlocking ribs  62  extending therefrom. Interlocking ribs  58  are defined, at least in part, by a joining surface  66 . Interlocking ribs  62  are defined, at least in part, by an engaging surface  68 . At least portions of joining surface  66  and engaging surface  68  are in contact as fastener  40  is in a closed position, as illustrated in  FIGS. 1-3 .  
         [0016]     Fastener  40  has a width W, measured in a transverse direction, a length L ( FIG. 1 ), measured in a longitudinal direction, and a height T, measured generally perpendicular to the transverse and longitudinal directions. At least a portion of joining surface  66  is defined by a generally transversely extending first planar surface  76 . At least a portion of engaging surface  68  is defined by a generally transversely extending second planar surface  78 .  
         [0017]     To open container  20 , a user may grasp first end  32  and separately grasp second end  34 . The user then may pull first end  32  away from second end  34 , thereby separating at least a portion of the first track  50  from the second track  52 . The first track  50  and the second track  52  of fastener  40  may not be separated at first end  42  and second end  44 . Therefore, fastener  40  provides access to the inside of container  20 .  
         [0018]     To close container  20 , a user may grasp fastener  40  at first end  42  and squeeze together tracks  50 ,  52  along the length L of fastener  40  to interlock tracks  50 ,  52  as illustrated in  FIG. 3 .  
         [0019]      FIG. 4  illustrates an alternative embodiment of the container  20  as a container  120 . Container  120  includes a first wall  122  having a first end  132 , a second wall  124  having a second end  134 , and a fastener  140 .  
         [0020]     Fastener  140  includes a first track  150  and a second track  152 . The first track  150  includes a first base  154  with a first flange  156  and a first pair of interlocking ribs  158  extending therefrom. The second track  152  includes a second base  160  with a second pair of interlocking ribs  162  and a second flange  164  extending therefrom. Interlocking ribs  158  are defined, at least in part, by a joining surface  166 . Interlocking ribs  162  are defined, at least in part, by an engaging surface  168 . At least portions of joining surface  166  and engaging surface  168  are in contact as fastener  140  is in a closed position.  
         [0021]     Fastener  140  has a width W 1 , measured in a transverse direction, a length L 1  (not shown), measured in a longitudinal direction, and a height T 1 , measured generally perpendicular to the transverse and longitudinal directions. At least a portion of joining surface  166  is defined by a generally transversely extending first planar surface  176 . At least a portion of engaging surface  168  is defined by a generally transversely extending second planar surface  178 .  
         [0022]     To open container  120 , a user may grasp first end  132  and flange  156  and separately grasp second end  134  and flange  164 . The user then may pull flange  156  away from flange  164 , thereby separating at least a portion of the first track  150  from the second track  152 . Therefore, flanges  156 ,  164  provide a portion of fastener  140  to grasp when opening container  120  and may prevent tracks  150 ,  152  from separating from walls  122 ,  124  when the user pulls to open container  120 . Container  120  is closed in a similar manner as container  20 .  
         [0023]     Walls  22 ,  24 ,  122 ,  124  preferably have a thickness of about 1 mil, although any appropriate thickness may be used for container  20 ,  120 , including a range of about 0.1 mil to about 500 mil. As discussed below, containers  20 ,  120  and fasteners  40 ,  140  may be formed of any desired dimensions from a resiliently deformable, biodegradable polymer blend. Since walls  22 ,  24 ,  122 ,  124  are typically cast or blown and fasteners  40 ,  140  are desirably extruded, the differing forming techniques generally dictate differing desired material characteristics.  
         [0024]     Preferably, the material for fasteners  40 ,  140  is a degradable polymer. More preferably, fasteners  40 ,  140  are constructed of a biodegradable blend of starch, or other suitable material, and either a polyethylene or polypropylene. Fasteners  40 ,  140  may be any weight percent biodegradable material with the remainder being essentially polyethylene or polypropylene. Preferably, fasteners  40 ,  140  are about 1 to about 5 weight percent starch. While the biodegradable additive to the polymer material for fastener  40 ,  140  is described as starch based, other materials that provide a desirable degradation may be added to a polymer to produce a suitable material.  
         [0025]     While the materials for the biodegradable fasteners  40 ,  140  and container  20  will desirably degrade in accordance with accepted standards, such as ASTM standards, the disclosure of which is hereby incorporated by reference in its entirety, other materials that favorably degrade and may not meet the requirements of applicable standards are also within the scope of the embodiments of the invention.  
         [0026]     In one embodiment of manufacturing the fastener  40 , die extrusion is used. Tracks  50 ,  52  are extruded separately and may be joined and stored on a spool. Fastener  40  is then heat fused (welded) or adhered to walls  22 ,  24 . Seams  26 ,  28  may be heat fused as ends  42 ,  44  are simultaneously heat fused. Heat fusing is process to desirably seal seams  26 ,  28 , and ends  42 ,  44  as they are trimmed. To adequately heat fuse ends  42 ,  44 , pressure is applied as tracks  50 ,  52  are trimmed to produce ends  42 ,  44  while fusing tracks  50 ,  52  at ends  42 ,  44 . Ends  32 ,  34  are trimmed and seam  30  is heat fused, if not previously folded, to produce the container  20 . Container  120  is produced in a similar manner.  
         [0027]     While the invention has been described with respect to specific examples including preferred modes of carrying out the invention, those skilled in the art will appreciate that there are numerous variations and permutations of the above described systems and techniques that fall within the spirit and scope of the invention as set forth in the appended claims.

Technology Classification (CPC): 8