CA2062569C

CA2062569C - Protruding end stops for plastic reclosable fastener

Info

Publication number: CA2062569C
Application number: CA002062569A
Authority: CA
Inventors: Fox John Herrington, Jr.; Eric Anthony St. Phillips
Original assignee: Pactiv LLC
Current assignee: Pactiv LLC
Priority date: 1991-03-22
Filing date: 1992-03-10
Publication date: 2002-02-19
Anticipated expiration: 2012-03-10
Also published as: ATE145527T1; GR3021994T3; EP0505057A1; JP3009964B2; DE69215409D1; KR100230495B1; AU642589B2; JPH0591909A; AU1280092A; EP0505057B1; KR920017591A; CA2062569A1; US5131121A; DE69215409T2; DK0505057T3; ES2097276T3

Abstract

A fastener structure for thermoplastic bags, comprising: a pair of flexible plastic strips adapted to be secured to the facing side walls along the mouth of a thermoplastic bag; reclosable interlocking male and female profile elements on the respective strips; and a slider adapted to open and close the male and female profile elements; and end stops located at the opposite ends of the reclosable fastener.
Each of the end stops is formed from the material at the opposite ends of said reclosable fastener and protrudes from said fastener a distance adequate to engage the slider, and to prevent movement of the slider past the respective ends of the bag.

Description

~~ ~~~
F-6131-L(PAC) Pratrixling Ehd Clamp Stops for Plastic Recl~able Fastener The present invention relates to a fastener structure for a thermoplastic bag.
Plastic reclosable fasteners or zippers with sliders are well Jmo~.m in the art. ~lhe plastic zippers inclr~de a pair of male and female fastener ele~~nts in the form of reclosable interlocking rib and groove elements with a slider for opening and closing the rib and groove elements. In the manufacture of thermoplastic film bags, a pair of these male and female fastener elements extend along the mouth of the bag and these male and female elements are adapted to be secured in any suitable manner to the flexible walls of the thermoplastic film bags. These el~ents may be integral marginal portions of such walls or they may be extnzded separately and thereafter attached to the walls along the mouth of the bag.
Various arrangements have been utilized heretofore to maintain the slider on the zipper. In one of the more ~rnrentional arrangements the slider includes a separator finger that eactends dawn between the integral locking rib and groove elements as the slidex is moved from one edge of the bag to the other edge of the bag. When the bag is opened, the only thing to stop the slider was the side seam at the edge of the bag when the slider finger c~.s into contact with it.
This pcrior art is descxib~l in US-A-3 , 790, 992 .
In that patent there is disclosed an improvement wherein the heat seals that join the rib and groove elements are wider at ors end than the second edge of the bag and the wider seal being of a width at least equal to the length of the slider frcan its closing end to the finger so that.the slider will remain fully on the bag at the end of its travel when opening the bag. The patent points out that these seal areas provide stops for the slider.
Another arrangement for prwidirx~ stops at the end of the zipper is disclosed in US-A-3,259,951. In that patent the bite ends of the F-6131-L(PAC)

- 2 -interlocking or mating atrips are permanevritly joined or sealed to each other at the ends with stop members sealed between the opposite errs of these members to stop the longil mav~ent of the slider therealong.
It wr~uld be desirable t.~~ provide a plastic bag having a zipper that is operated by a slider whQrein the zipper is texm:inated with protruding erxi stops formed fram tl~e zipper to prevent the slider from moving off past the ends of the zipper. With this arrangement it is nat necessary to add an additional stop element to tl~ zipper nor to rely on the strength of the seam at the edge of the bag for preventing the slider frcaa moving past the erx~.s of the bag.
It is an object of the present invention to provide a plastic bag having a fastener that :is operated by a slider wherein the fastener is terminated with protruding end stops formed from the fastener to engage the slider arxi prevent the slider from moving off past the ends of the zipper.
According to one aspect of the invention there is provided a reclosable fastener structure for thermoplastic bags, comprising a pair of flexible plastic strips adapted to be secured to the facing side walls along the mouth of a ylastic bag; reclosable interlocking male and female profile el~nts on the respective strips; and a slider adapted to open and close the male and female profile el~nts, characterised by:
end stop means located at the opposite ends of said reclosable fastener st~:-ucture, each of said end stop means being formed frown the material at the opposite ends of said reclosable fastener arxi pratzvding frcmm said fast~er~er a distance adequate t~ engage, the slider, and to prevent movement of the sl9~der past the respective ends of the bag.

F-6131-L(PAC)

- 3 -Preferably said end stclO pans protrudes frcan, at least one of the sides of said structure. lire preferably said end stop means protrudes frcen both of the sides of said fastener structure.
Accordii~g to another aspect of the invention there is provided a method of forming end stops for the slider of the fastener structure described above, ecanprising:
clamping and sealing together a pair of the flexible plastic strips and the facing side walls at a seal area at the ends of the bag to reduce the material thickness of the pair of flexible plastic strips and the facirg side walls of the bag sandwiched therebetween and conca~rently increasing the thickness of an adjacent area of the reclosable fastener adjacent the seal area to provide protrudir~g structure from the fastener thereby providing pratrudi.ng end stops for preventing movement of the slider past the ends of the bag.
Preferably the protnxdirig end stops are formed by ultrasonically smashing the adjacent area of the reclosable fastenPx.
Accordiryg to a further asp~t of the invention there is provid~l a thermoplastic bag cxattprising a pair of facing side walls defining an open myth of one end of the bag, and a fastener structure as described above dispos~i along said open mouth.
Reference is now made to the accompanying drawings, in which:
Figs. la and 1b are fractional elevational views showing the op~site ends of the top of a thermoplastic bag with protruding end stops on the plastic reclosable fastener in accordance with the present invention; and Fig. 2 is a perspective view showing the method of forming the protruding end stops on the plastic reclosable fastener.
Referring to Figs. la, 1b and 2, there is illustrated a ther~plastic bag B having a plastic slider 10 and a profiled plastic reclosable F-6131-L(PAC)

- 4 -fastener or zipper 11 with end stops 30a, 30b embodying the present invention. Zhe slider :LO and zipper 11 are particularly suited for thermoplastic bags and t:he like and the slider 10 has been illustrated in Figs. la and lb assEqnbled on the zipper 11 at the 'fop edge ar mouth of a thermoplastic bag B.
In Fig. la the slider 10 has been illustrated at the left hard erxi of the zipper 11 which is the closed end. In Fig. lb the zipper 10 has been illustrated at the right hand erxi of the zipper 11 which is the opened exxi of the zipper-. In opening arxi closing the zipper 11 it will be u~r3ers-tood that the :>lider 10 will move fran the closed end in Fig.
la to the opened erxi in Fig. lb and vice versa.
The bag B may be made fran any suitable Mastic film such for example as polyethylene or polypropylene or equivalent material. The bag B is formed by a pair of flexible plastic sheets 12 and 13 joined at the bottc~n and having a top edge, with a pair of flexible plastic strips 14 and 15 havirx~ sharable plastic means exterr3ing along the length thereof ~ris:ing reclosable interlocki~ male arxi female profile elements in the form of rib and groove elements 16 and 17 on the respective strips t:o form the zipper il. This is best shaven in Fig. 2.
The strips 14 and 15 may be extruded separately arid attached to the respective sides of the bag mouth or the strips 14 and 15 may be exintegral with 'the sides of the bag mouth. The strips 14 and 15 include profiled tz-acks 18 and 19 esalong the length thereof and parallel to the rib and groove elements 16 arxi 17 and the rib arxi groove el~ts 16 and 17 preferably have complementary cross-sectional shapes such that they are closed by pressing the bottc~n of the elements t:agether first arr3 then rolling the elements to a closed position toward the top thereof. The cxoss-sectional shapes of the interlocking male and female el~nents having the rib and groove profiles 16 and 17 are cLi.sclosed in WU 91/13564.

r '1 F-6131-L(PAC)

- 5 -It is to be hod 'that the present irnrention is not limited to the shapes of the rib and groove profiles illustrated herein and that other shapes can be utilized in connection with the present invention.
It is also to be wxlers-tood that the present invention is nat limited to the particular ~struction of the slider 10 disclosed herein arx3 that ather zipper sliders may be utilized in connection with the present invention.
As may be seen in Fig. 2 the slider 10 straddles the zipper 11 at the top of the bag B aryl is adapted for opening and closing the reclosable fastener elements 16 and 17 of the zipper 11. The slider 10 is formed from a single piece of gilded plastic ca~rising a separator finger 9 and interloc3tir~g complementary structure moving along the zipper 11.
The separator finger 9 cooperates with the zipper 11 in such a manner as to provide a self-locxihg feature for the slider and a leakproof bag. The slider 10 may be molded fraan any suitable plastic such for example as nylon, polypmopylene, polystyrene, "Delrin"* or ABS.
Referring to Fig. 2 it will be seen that the slider 10 is of the foldable type with wings 21 and 22 which have been folded down at the hinge structure 21a and 21b located at t~ top of the slider body 20 so that the wings are :in the folded sidewall position against the edges of the slider body 20. The depen3ing legs 20a and 20b are positioned on the outer side of the strips 14 and 15 and the body 20 of the slider 10 rests on the top of the tracks 18 arx3 19.
When the sidewalk 21 and 22 are in the folded position as shown in Fig. 2 a o~ression-type lad mechanism (not shown) locks the sidewalk 21 arr3 22 in folded position with the depending legs 20a arx3 20b. In this assembled position, the shoulders 21c and 22c (not shown) on the sidewalk 21 aryl 22 are positioned beneath the battcen of the fas~ter~er elett~ts 16 and 17 to prevent the slider 10 fran being lifted off the zipper 11. The foldable depending sidewalk 21 arxi 22 e~ctend frcen an opening end l0a of the slider 10 to a closing end lOb.
* Trademark F-6131-L(PAC)

- 6 -It will be nested that the main slider body 20 ardd the separator finger 9 are wider at the opening erxl l0a than at the closing end lOb.
Similarly the sidewalk 21 and 22 and the depending legs 20a and 20b are spaced wider apart at the opening end l0a of the slider 10 to permit the separation of the rib and groove elements 16 and 17 by the finger 9 engaging the tracks 18 and 19 and are spac~l sufficiently close together at the closing end lOb of the slider to press the rib and groove elements 16 and 17 into interlocking relationship as the slider 10 is waved in a fastener closing direction as illustrated by the arrow in Fig. 1a. The arrow in Fig. lb illustrates movement of the slider 10 in the fastener opening dire<:tion.
Referring again to Figs. la and lb it will be seen that the opposite ends of the zipper 11 are provided with end stops 30a, 30b. Each of the end stops 30a, 30b is formed fr~n the material at the opposite ends of the zipper 11 and protrude frcan the zipper a distance adequate to engage the slider 10 and prevent the slider from going past the respective ends of the zipper and caning off the bag.
The opposite ends of the profile elements 16, 17 of the zipper track are ultrasonically smashed to provide the end stop structure 30a, 30b protruding from the fastener or zipper 11 a distance adequate to engage the slider l0 and prevent mr~veanexat of the slider past the respective ends of the bag. As may be seen in Fig. 2 a pair of reciprocating anvils 31 and 32 are employed to perform the smashing of the zipper track ends.
The anvils 31 and 32 are each provided with cooperating recesses 31a, 31b and 32a, 32b which engage the bite sides of the zipper 11 and produce protruding bumps on the opposite sides of the zipper ends in the form of end stops 30a and 30b which interfere with the movement of the slider 10 past the ends of the bag. The end stop 30a will engage the opening end 10a of the slider 10 by engaging the end of the shoulder 21c. A double anvil arrar~g~nent is shown in Fig. 2 to concurrently ultrasonically smash the other end of the adjacent zipper 11 on the adjacent bag B to produce the end stop 30b. taken the slider F-6131-L(PAC) l0 is moved to the bite end of the bag as shown in Fig. lb the cling end 10b of the slider will engage the end stop 30b.
Fr~n the foregoing description it will be sin that the end stops 30a and 30b are forms by clamping and sealing tcx~ethex the pair of flexible plastic strips 14, 15 and the facing sidewalls at a seal area at the ite ends of the bag to reduce the material thic~ess of the pair of flexible plastic strips and the facing sidewalls of the bag sandwiched therebetween and concurrently increasing the thiclmess of the adjacent area of the reclosable fastener 11 adjacent the seal area to provide the protruding stop structure 30a and 30b from the fastener thereby providing protn~ding end stops 30a and 30b for preventing movement of the slider 10 past the ends of the bag.
It is to be wxlerstood that anvils of other shapes than those illustrated in Fig. 2 may be ~xtilized in producing the protruding structure at the ends of the zipper 11 so long as the end stops are produced from the material at the ends of the zipper. In this way the zipper will be provided with end stops which prevent the slider 10 from going past the end of the zip~x and c~nir~g off the bag but has elimir~at~l the necessity for providing additional structure separate fr~n the zipper for producing the end stop.
While a preferred embodiment of the irnrention has been described and illustrated, it is to be understood that further modifications ther~f may be made within the scope of the appended claims.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A reclosable fastener structure for thermoplastic bags, comprising a pair of flexible plastic strips adapted to be secured to the facing side walls along the mouth of a thermoplastic bag; reclosable interlocking male and female profile elements on the respective strips; and a slider adapted to open and close the male and female profile elements, characterised by:
end stop means located at the opposite ends of said reclosable fastener structure, each of said end stop means being formed from material at the opposite ends of said reclosable fastener structure and protruding from said fastener a distance adequate to engage the slider, and to prevent movement of the slider past the respective ends of the bag.

2. A fastener structure according to claim 1 wherein said end stop means protrudes from at least one of the sides of said structure.

3. A fastener structure according to claim 1 or 2 wherein said end stop means protrudes from both of the sides of said fastener structure.

4. A method of forming end. stops for the slider of a reclosable fastener structure as defined in any one of claims 1 to 3, comprising:
clamping and sealing together a pair of the flexible plastic strips and the facing side walls at a seal area at the ends of the bag to reduce the material thickness of the pair of flexible plastic strips and the facing side walls of the bag sandwiched there between and concurrently increasing the thickness of an adjacent area of the reclosable fastener adjacent the seal area to provide protruding structure from the fastener thereby providing protruding end stops for preventing movement of the slider past the ends of the bag.

5. A method according to claim 4 wherein the protruding end stops are formed by ultrasonically smashing the adjacent area of the reclosable fastener.

6. A thermoplastic bag comprising a pair of facing side walls defining an open mouth of one end of the bag, and a fastener structure as defined in any one of claims 1 to 3 disposed along said open mouth.