Methods of manufacturing reclosable package having a slider device

Information

  • Patent Grant
  • 6581358
  • Patent Number
    6,581,358
  • Date Filed
    Thursday, June 28, 2001
    23 years ago
  • Date Issued
    Tuesday, June 24, 2003
    21 years ago
Abstract
A method of making packages having a reclosable zipper construction openable and closable by a slider device, on a horizontal form, fill and seal process. The method includes applying the slider device to the zipper construction prior to incorporating the zipper construction with side panels to form the package. A tamper-evident seal may be provided encasing the slider device to provide indication whether access has been gained to the interior of the package.
Description




FIELD OF THE DISCLOSURE




This disclosure concerns reclosable packages. In particular, this disclosure describes reclosable packages manufactured from form, fill, and seal machines, the packages having slider devices for opening and closing the packages, and methods of manufacturing the packages.




BACKGROUND




Form, fill, and seal technology is known in the packaging industry as a method to package consumable goods. Consumable goods that are not used completely when the package is initially opened rely on a zipper closure to reclose the package and keep the remaining contents fresh. Examples of consumable goods that are often packaged in packages with a zipper closure include potting soil, fertilizer, pet food, dog biscuits, and many different foods edible by humans.




Often, the opening and closing of the zipper closure is facilitated by a slider device that is mounted on the zipper closure. The slider device is constructed to pry apart the interlocking zipper closure members when the slider device is moved in a first direction along the zipper, and to engage the interlocking zipper closure members when the slider device is moved in a second, opposite direction along the zipper. For some applications, a tamper-evident seal, to notify whether access has been gained to the zipper closure, is desired. Improvements in these types of packages are desirable.




BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

is a perspective view of a flexible, reclosable package;





FIG. 2

is a schematic, cross-sectional view of a flexible, reclosable package similar to that depicted in

FIG. 1

;





FIG. 3

is a schematic, cross-sectional view of a flexible, reclosable package having a tamper-evident seal;





FIG. 4

is a schematic, cross-sectional view of another embodiment of a flexible, reclosable package having a tamper-evident seal;





FIG. 5

is a schematic, cross-sectional view of a flexible, reclosable package having a tamper-evident seal and a peel seal;





FIG. 6

is a schematic, perspective view of a horizontal form, fill, and seal machine for manufacturing and filling packages having a zipper closure and slider device attachment;





FIG. 7

is an enlarged schematic plan view of a portion of the process depicted in

FIG. 6

;





FIG. 8

is an enlarged schematic side view of a portion of the process depicted in

FIGS. 6 and 7

, viewed from the opposite side of

FIGS. 6 and 7

;





FIG. 9

is an enlarged schematic, cross-sectional view of a process for providing a perforated tamper-evident seal, such as for the packages of

FIG. 3

;





FIG. 10

is an enlarged schematic, cross-sectional view of a process for providing a perforated external tamper-evident seal and an internal tamper-evident seal;





FIG. 11

is an enlarged schematic, cross-sectional view of a process for providing a perforated tamper-evident seal, such as for the package of

FIG. 4

; and





FIG. 12

is an enlarged schematic, cross-sectional view of a process for removing edges of film;





FIG. 13

is an enlarged schematic, cross-section view of a portion of another process for providing an external tamper-evident seal and an internal tamper-evident seal;





FIG. 14

is an enlarged perspective view of a portion of the process of

FIG. 13

;





FIG. 15A

is a front view of an apparatus for use with the process of

FIG. 13

;

FIG. 15B

is a side view of the apparatus of

FIG. 15A

;

FIG. 15C

is a rear view of the apparatus of

FIG. 15A

;

FIG. 15D

is a side view of a portion of the apparatus of FIG. A, the portion being removed from the apparatus; and





FIG. 16

is a schematic perspective view of another portion of the process of FIG.


13


.











SUMMARY OF THE DISCLOSURE




The present disclosure relates to a method of manufacturing a package, such as a flexible bag, having a resealable, reclosable zipper mechanism; opening and closing of which is accomplished by a slider device mounted on the zipper mechanism. A tamper-evident seal can be provided on the exterior or interior of the slider device so as to provide evidence whether access has been gained to the interior of the package. Alternately or additionally, a hermetic peel seal can be included in the package.




In particular, the present disclosure relates to a form, fill and seal process that manufactures the flexible package, fills the package with items, and seals the filled package. The zipper mechanism, the slider, and any seals are applied to the package in the same process as filling of the package.




The methods of this disclosure involve, in general, providing a zipper having interlocking closure members, incorporating a “park” notch within the zipper, locating the slider device within the “park” notch, attaching the zipper and slider to side panels as appropriate to provide a package.




In one particular embodiment, the present disclosure is directed to a method of manufacturing a reclosable package having a zipper closure and a slider device. The method includes providing a closure construction having a first closure profile and a second closure profile and providing a slider device. The slider device is constructed and arranged for mounting on the closure construction and for interlocking the first closure profile with the second closure profile when the slider device is moved in a first direction, and for disengaging the first closure profile from the second closure profile when the slider device is moved in a second opposite direction. The slider device is mounted onto the closure construction, and the closure construction, with the slider device mounted thereon, is transported in a straight-line between a first film panel and a second film panel. The closure construction, together with the film panels, are formed into a resealable package.




This disclosure also relates to the resealable, reclosable packages made by the methods of this disclosure.




DETAILED DESCRIPTION




The addition of a slider device to a flexible package, such as a bag, is advantageous to aging or arthritic persons not having the physical ability to use just a zipper closure to reseal a bag. The process described herein adds a slider device to bags manufactured from form, fill, and seal machines. In some embodiments, a tamper-evident seal and/or a peel seal is also provided by the process described herein.




A flexible, reclosable package


10


having side panels


12


and


14


defining interior


11


is shown in

FIGS. 1 and 2

. Side panels


12


,


14


are sealed together at side seams


13


,


15


and at bottom seam


17


. A zipper closure arrangement having mating profiles to open and close (unseal and reseal) the bag


10


is shown at


20


. The zipper closure


20


can include a variety of configurations and structures. For example, the zipper closure


20


can be constructed according to U.S. Pat. Nos. 4,240,241; 4,246,288; or 4,437,293; each of which is incorporated by reference herein. The zipper closure


20


includes a first mating profile


22


(

FIG. 2

) and a second mating profile


24


(

FIG. 2

) that engage and disengage, as appropriate, to open and close the bag


10


. Zipper closure


20


extends from a first edge


16


of the bag


10


to a second edge


18


across a mouth


21


.




A slider device


30


is mounted on zipper closure


20


to facilitate opening and closing zipper closure


20


. Slider devices and how they function to open and close zipper closures, in general, are taught, for example, in U.S. Pat. Nos. 5,063,644; 5,301,394; 5,442,837, and 5,664,229, each of which is incorporated by reference herein. A notch


23


(

FIG. 1

) is disposed within zipper closure


20


adjacent to a first edge


16


in the bag


10


. Notch


23


is designed to provide a “park place” into which slider device


30


settles when zipper closure


20


is sealed and slider device


30


is at the first edge


16


. Such a notch


23


may decrease any tendency for an incomplete interlock between first mating profile


22


and second mating profile


24


.





FIG. 3

illustrates a flexible bag


100


similar to bag


10


of

FIGS. 1 and 2

, except that bag


100


includes a tamper-evident structure


50


disposed over slider device


30


. By “tamper-evident”, it is meant that it provides an indication to the consumer as to whether the package


100


has been previously opened. In order to access the interior


11


of the package


100


, the tamper-evident structure


50


needs to be penetrated. In this embodiment, the tamper-evident structure


50


covers and forms a complete enclosure around the zipper closure


20


and slider device


30


; tamper-evident structure


50


is formed by sealing the tops of side panels


12


,


14


over slider device


30


. In order to gain access to the slider device


30


and bag interior


11


, the tamper-evident structure


50


needs to be penetrated. Various modifications of tamper-evident structures are known throughout the art of resealable packaging; additional examples of packages with tamper-evident structures are illustrated in

FIGS. 4 and 5

.





FIG. 4

illustrates a flexible bag


120


, similar to bag


10


of

FIGS. 1 and 2

and bag


100


of

FIG. 3

, except that bag


120


has an internal tamper-evident structure


60


disposed between zipper closure


20


and the interior


11


of bag


120


. In order to gain access into the interior


11


of bag


120


, tamper-evident seal


60


needs to be penetrated.

FIG. 5

shows a flexible bag


140


similar to bag


100


of

FIG. 3

, except that bag


140


also includes a peel seal


80


disposed between zipper closure


20


and the interior


11


of bag


140


. Other embodiments of tamper-evident structures are described in U.S. Pat. No. 5,713,669, herein incorporated by reference.




Each of these bags described and disclosed in

FIGS. 1 through 5

can be manufactured by a horizontal form, fill and seal machine in accordance with the present disclosure. The bag, whether with or without a tamper-evident seal and/or a peel seal, is manufactured, filled, and sealed by a single process that includes multiple sequential steps. The zipper closure


20


, slider device


30


and any tamper-evident structure are applied to the bag prior to the bag being filled with items.




Referring to

FIGS. 6 and 7

, a horizontal form, fill and seal process, in accordance to the present disclosure, is shown at


200


in FIG.


6


. As illustrated in

FIGS. 6 and 7

, the process line progresses from right to left; that is, the final filled package is at the left of the figures. The bag or package is manufactured upside-down so that the filling takes place through the bottom of the bag. Throughout this disclosure, the side of the bag having the zipper closure will be referred to as the “top” of the bag.




Polymeric film


210


, which will provide the side panels


12


,


14


(FIGS.


1


through


5


), is provided on a roll. In another embodiment, film


210


may be extruded or otherwise formed immediately before this horizontal form, fill and seal process, thereby eliminating the step of winding the film after forming and then unwinding when the bags are made and filled. A series of tensioners


205


(

FIG. 6

) helps to control the tension on the film


210


during the bag-making process. From the tensioners


205


, the film progresses to a “V-board”


250


where the film


210


is folded. A slitter knife


240


close to the base of the V-board


250


slits film


210


into two webs of film


251


,


252


. Additional features of the V-board


250


are discussed below.




An extended length of zipper closure


20


(with first closure profile and second closure profile interlocked) is provided via spool


220


simultaneously with the film


210


. Notch


23


(

FIG. 1

) is punched into zipper closure


20


by an in-line punch


223


that may be a die, knife, stamp or other such process. Notch


23


is formed in the profile of the zipper closure


20


before the zipper closure


20


is incorporated into the package. Referring still to

FIGS. 6 and 7

, slider device


30


, provided from a spool


230


, is parked into the notch


23


punched in zipper closure


20


by applicator


232


. If misaligned on the zipper closure


20


or notch


23


, the slider device


30


can be phased into register with the notch


23


by sliding or moving the slider device


30


along the zipper profile


20


by guides or the like, until the slider device is in register with the package slider “park” position, that is, notch


23


.




The punching of notch


23


by punch


223


and the application of slider device


30


by applicator


232


may be done as a continuous procedure, that is, with zipper closure


20


being continuously unwound from spool


220


and applied to film halves


251


,


252


. Alternately, notch


23


and slider device


30


may be applied in a step-wise function; that is, zipper closure


20


can be incrementally indexed to punch


223


and to applicator


232


. The zipper closure


20


would be indexed a distance generally equal to the width of the package from first edge


16


to the second edge


18


(FIG.


1


). In such a process, it may be preferable to include various tensioner rolls to compensate for the incremental feeding of zipper closure


20


with the parked slider device


30


to the film halves


251


,


252


.




The zipper closure


20


with the parked slider device


30


is fed between the two halves


251


,


252


of film


210


. A pair of guides or fingers (not illustrated) may be used to spread apart film halves


251


,


252


to allow easier passage of the combined zipper closure


20


/slider device


30


therethrough. With this arrangement, the combined zipper closure


20


and slider device


30


can be fed between the film halves


251


,


252


without having to progress through bends or around rollers. That is, the combined zipper closure


20


and slider device


30


is allowed to travel in a straight configuration from the point where slider device


30


is applied to the zipper closure


20


to the point where the combined zipper and slider are attached to film halves


251


,


252


. Preferably, once attached to film halves


251


,


252


, the straight configuration (i.e., with no bends or turns) is maintained.




V-board


250


, as used in the method of the present disclosure, bends and configures film


210


into the desired form, and is instrumental in applying zipper closure


20


with the parked slider device


30


to the film halves


251


,


252


. Slitter knife


240


, for slitting into film halves


251


,


252


, is positioned at or near the bottom of V-board


250


.




As illustrated in

FIGS. 6

,


7


and


8


, V-board


250


is a generally two-dimensional board defined by a triangular face


450


with a top edge


451


and two angled edges


452


,


454


. Generally, the board is “v” shaped. A flat sheet of film


210


is folded into two halves by passing the film against the two angled edges


452


,


454


of V-board


250


. As best seen in

FIG. 8

, film


210


is brought behind the top edge


451


and face


450


of the board, and is then folded by the two angled edges


452


,


454


. The outer edges


211


,


212


of film


210


form the bottom edges


251




b


,


252




b


of the film halves


251


,


252


, respectively, and the centerline


215


of film


210


forms the top edges of the resulting package. Film


210


is slit by slitter knife


240


at centerline


215


to provide top edges


251




t


(not illustrated),


252




t


of the two individual film halves


251


,


252


.




Preferably, V-board


250


includes a slot, slit, hole, or other aperture


255


(

FIG. 7

) through its face near the slitter knife


240


to accommodate passing the zipper closure


20


and slider device


30


therethrough. In accordance with the present disclosure, the zipper closure


20


is fed into slot


255


at the base of the V-board


250


, preferably fairly soon after slitter knife


240


produces film halves


251


,


252


from film


210


. The slot


255


allows the zipper closure


20


be brought between the film halves


251


,


252


without a need for bending or turning corners with zipper closure


20


with slider device


30


.




Because the bag or package is manufactured upside-down (that is, the bottom seam


17


(

FIGS. 1 through 5

) will be at the top of the line, and the “top” of the bag is at the bottom of the line), the zipper closure


20


, with the parked slider device


30


, is positioned at the bottom of the film halves


251


,


252


.




Heated seal bars


260


provide vertical seals on the film and zipper closure combination. These vertical seals will eventually result in side seams


13


,


15


of package


10


in FIG.


1


. In one embodiment, a single heated seal bar


260


is used. In a second embodiment, a plurality of heated seal bars


260


is used. Typically, each seal bar


260


has a first bar and a second bar (not illustrated) on opposite sides of the film. Heat may be provided from one or both sides; additionally and/or alternatively, the temperature from one side to another may be the same or may be different. Multiple seal bars, such as shown in

FIG. 6

, may be heated to different temperatures. The process may be designed so that each seam area is contacted by multiple seal bars, or by only one bar-. Rollers can be used as desired to feed and stabilize the film and zipper closure.




Top seal bar


265


, positioned at the bottom of the line, seals zipper closure


20


to the film halves


251


,


252


. Zipper closure


20


has first closure profile


22


and second closure profile


24


interlocked (FIG.


2


), so that after the film halves


251


,


252


are attached to the two closure profiles


22


,


24


, the package is ready to accept items or material into the interior


11


(FIGS.


1


through


5


).




A tamper-evident structure, for example, structure


50


of FIG.


3


and structure


60


of

FIG. 4

, provides an indication to the consumer as to whether the package


100


,


120


(

FIGS. 3 and 4

, respectively) has been previously opened. In order to access the interior


11


of the package


100


,


120


, the tamper-evident structure


50


,


60


needs to be penetrated. This is typically accomplished by cutting and/or removing the structure


50


,


60


. In some embodiments, in particular with the tamper-evident structure


50


of

FIG. 3

, the structure


50


may include a scored or perforated area to aid in the removal of at least a portion of the tamper-evident structure


50


.




A tamper-evident structure, such as structure


50


of

FIGS. 3 and 5

, can be produced by modifications to top seal bar


265


of horizontal form, fill and seal process


200


. For example, referring to

FIG. 9

, an unfinished package


100


′, similar to finished package


100


of

FIG. 3

, can be made by using a top seal bar


465


that has first sealing surfaces


420


and second sealing surfaces


450


. Zipper closure


20


, with slider device


30


mounted thereon, is positioned between film halves


251


,


252


. The two halves of seal bar


465


are brought together so that first sealing surfaces


420


and second sealing surfaces


450


contact the film halves


251


,


252


. First sealing surfaces


420


are positioned to provide pressure and, typically, heat to the area where the flanges of zipper closure


20


meet the film


251


,


252


, so as to make a seal between zipper closure


20


and the film. Second sealing surfaces


450


are positioned to provide pressure and, typically, heat to an area below slider device


30


and form a seal between film halves


251


,


252


. This will provide a tamper-evident structure


50


(shown in

FIGS. 3 and 5

at the top of the package) which encases slider device


30


.




An adjustable depth perforator


350


may be combined with seal bar


465


to provide perforations or some other weak point in the film between the area of the zipper closure/film seal and the area of the top film seal. This weakened area allows easy removal of the tamper-evident structure


50


by the consumer. Preferably, the weakened area is positioned close to the area where the zipper closure


20


is sealed to the film and the slider device


30


, to minimize the amount of film remaining close to slider device


30


after the tamper-evident structure


50


is removed from the package.




Attention is now directed to

FIGS. 13 through 16

, which depict another embodiment of a horizontal seal bar


565


, one that can be used with a slider guide


600


. In

FIGS. 13 and 14

, seal bar


565


has first sealing surface


520


, second sealing surface


550


and an outside surface


560


. In

FIG. 13

, zipper closure


20


, with slider device


30


mounted thereon, is positioned between film halves


251


,


252


. Similar to as described in reference to seal bar


465


of

FIG. 9

, two seal bars


565


are brought together so that first sealing surfaces


520


and second sealing surfaces


550


contact the film halves


251


,


252


. In

FIG. 13

, first sealing surfaces


520


are positioned to provide pressure and, typically, heat to the area where the flanges of zipper closure


20


meet the film halves


251


,


252


, so as to make a seal between zipper closure


20


and the film. Second sealing surfaces


550


are positioned to provide pressure and, typically, heat to an area below slider device


30


and form a seal between film halves


251


,


252


to provide a tamper-evident structure


50


(shown in

FIGS. 3 and 5

at the top of the package) which encases slider device


30


.




Seal bar


565


is designed for use with slider guide


600


, shown in FIG.


13


and in various views in

FIGS. 15A through 15D

. Slider guide


600


is constructed to protect zipper closure


20


and slider device


30


from first and second sealing surface


520


,


550


of seal bar


565



FIGS. 13 and 14

) during forming of the various seals, and to provide an insert between film halves


251


,


252


at first sealing surfaces


520


.




Slider guide


600


includes a generally tubular body


605


through which zipper closure


20


and slider device


30


can pass. A portion of the tubular body


605


is preferably removed, as best shown in

FIG. 16

, to facilitate sealing of film halves


251


,


252


with seal bar


565


, which is not shown in FIG.


16


. First surface


520


of seal bar


565


contacts film halves


251


,


252


in the removed region. Slider guide


600


is designed so that zipper closure


20


, with slider device


30


thereon, moves from left to right through slider guide


600


in FIG.


15


B.




Slider guide


600


further includes a separating fin


610


, best seen in FIG.


15


D. Separating fin


610


includes a horizontal fin


615


and a gusset


612


. When a zipper closure


20


is positioned within slider guide


600


, horizontal fin


615


extends away from tube body


605


toward zipper closure


20


and separates zipper closure


20


; that is, a portion of separating fin


610


, in particular horizontal fin


615


, is disposed between portions of first and second mating profiles


22


,


24


(FIG.


2


). Horizontal fin


615


facilitates sealing of film halves


251


,


252


to first and second mating profiles


22


,


24


by minimizing the occurrence of having first and second mating profiles


22


,


24


seal to one another.




Separating fin


610


is attached to mounting member


620


of slider guide


600


; mounting member


620


extends out from tubular body


605


and provides a mounting area for slider guide


600


as needed. A gusset


612


can be included on fin


610


to strengthen the attachment of fin


610


to mounting member


620


.





FIG. 16

depicts the positioning of slider guide


600


in relation to film halves


251


,


252


, zipper closure


20


and slider device


30


. The process progresses from right to left, as depicted by the arrow. Slider guide


600


would be positioned behind the V-board


250


shown in FIG.


7


. Zipper closure


20


would pass through slot


255


and into slider guide


600


. Alternately, slider guide


600


can be positioned within slot


255


in V-board


250


, so that a portion of slider guide


600


is on the left of V-board


250


and a portion is on the right.





FIG. 10

shows an unfinished package


160


. Package


160


is similar to package


100


' of

FIG. 9

, except that package


160


includes a second tamper-evident structure


60


internal to slider device


30


and zipper closure


20


. Package


160


can be made using the seal bar


465


with first and second sealing surfaces


420


,


450


, and perforator


350


, as discussed above, to form tamper-evident structure


50


. Internal tamper-evident structure


60


can be integrally formed with first and second closure profiles


22


,


24


(

FIG. 2

) when zipper closure


20


is extruded. A perforated line or a peel strip can be used at point


65


(

FIG. 10

) to allow for easy access to the bag interior.




In some embodiments, it may be desired to provide a perforated or weakened area in the film in an individual step, rather than simultaneously, with the creation of the seals.

FIG. 11

illustrates unfinished package


160


′, similar to unfinished package


160


of

FIG. 10

, except that package


160


′ has tamper-evident structure


50


already formed prior to the package


160


′ reaching perforator


350


. Tamper-evident seal


50


is provided by a seal bar (such as seal bar


465


of

FIG. 10

) and perforation is done in a subsequent step.




In some embodiments, no tamper-evident structure external to the slider device


30


is used; rather, only an internal tamper-evident structure


60


, such as on package


120


in

FIG. 4

, is used. For example,

FIG. 12

illustrates an unfinished package


120


', similar to finished package


120


of FIG.


4


. In many embodiments it is desired to minimize the amount of film present above the seal between the film halves


251


,


252


and the zipper closure


20


. A blade


360


may be used to slit the film and remove any undesired film.




The order of the steps for forming the seal between the zipper closure


20


, the film halves


251


,


252


, any optional tamper-evident structure, any perforation, and the side seams


13


,


15


(

FIG. 1

) by side seal bars


260


, can be rearranged so that the zipper closure


20


is sealed to the film before the side seals are produced. Generally, any perforation is done simultaneously or subsequent to forming a tamper-evident structure.




After the side seams are made and the closed zipper closure


20


is attached, the items or material


305


(for example, cereal, snack food, fertilizer, potting soil, etc.) to be contained in the resulting package is provided by hopper


300


. Hopper


300


includes valves, gates, and doors, as needed, to deposit an appropriate amount of item


305


into the package. A bottom seal bar


270


located at the top of the line is used to seal the bottom of the package and provide bottom seam


17


(

FIGS. 1 through 5

) once the package has been filled. A blade or knife


280


cuts the packages at the side seams to provide individual, filled packages


310


.




The above specification is believed to provide a complete description of the manufacture and use of particular embodiments of the invention. Many embodiments of the invention can be made without departing from the spirit and scope of the invention.



Claims
  • 1. A method of making and filling a reclosable package comprising a zipper closure and a slider device, the method comprising:(a) providing a closure construction having a first closure profile and a second closure profile; (b) providing a slider device constructed and arranged for mounting on the closure construction and for interlocking the first closure profile with the second closure profile when the slider device is moved in a first direction, and for disengaging the first closure profile from the second closure profile when the slider device is moved in a second opposite direction; (c) mounting the slider device onto the closure construction; (d) forming a plurality of seals between first and second film panels of a film web to form a reclosable package having at least one unsealed seam; (e) incorporating the closure construction with the slider device mounted thereon into the resealable package by passing the closure construction with the slider device mounted thereon in a straight-line through a slider guide between the first and second film panels of the film web, the film web forming a tamper evident structure over the slider device to indicate whether access has been gained to the slider device; and (f) filling the resealable package with an item.
  • 2. The method according to claim 1, wherein the step of mounting the slider device onto the closure construction comprises:(a) punching a notch in the closure construction; and (b) mounting the slider device within the notch in the closure construction.
  • 3. A reclosable package made by the method according to claim 1.
  • 4. A reclosable package made by the method according to claim 2.
CROSS REFERENCE TO RELATED APPLICATIONS

This application is a division of application Ser. No. 09/467,854, filed on Dec. 20, 1999 U.S. Pat. No. 6,293,896, which application claims benefit of provisional U.S. Ser. No. 60/164,531, filed on Nov. 10, 1999.

US Referenced Citations (9)
Number Name Date Kind
3246444 Paisley Apr 1966 A
4437293 Sanborn Mar 1984 A
5301394 Richardson et al. Apr 1994 A
5431760 Donovan Jul 1995 A
5713669 Thomas et al. Feb 1998 A
5788378 Thomas Aug 1998 A
5816018 Bois Oct 1998 A
5947603 Tilman Sep 1999 A
5956924 Thieman Sep 1999 A
Provisional Applications (1)
Number Date Country
60/164531 Nov 1999 US