Background to the Invention
[0001] This invention generally relates to zippers for use in reclosable packaging, such
as bags or pouches. In particular, the invention relates to string zippers for reclosable
bags.
[0002] Reclosable bags are finding ever-growing acceptance as primary packaging, particularly
as packaging for foodstuffs such as cereal, fresh vegetables, snacks and the like.
Such bags provide the consumer with the ability to readily store, in a closed, if
not sealed, package any unused portion of the packaged product even after the package
is initially opened.
[0003] Reclosable bags comprise a receptacle having a mouth with a zipper for opening and
closing. In recent years, many zippers have been designed to operate with a slider
mounted thereon. As the slider is moved in an opening direction, the slider causes
the zipper sections it passes over to open. Conversely, as the slider is moved in
a closing direction, the slider causes the zipper sections it passes over to close.
Typically, a zipper for a reclosable bag includes a pair of interengageable profiled
closure strips that are joined at opposite ends of the bag mouth. The profiles of
interengageable plastic zipper strips can take on various configurations, e.g. interlocking
rib and groove elements having so-called male and female profiles, interlocking alternating
hook-shaped closure elements, etc. Reclosable bags having slider-operated zippers
are generally more desirable to consumers than bags having zippers without sliders
because the slider eliminates the need for the consumer to align the interengageable
zipper profiles before causing those profiles to engage.
[0004] In one type of slider-operated zipper assembly, the slider straddles the zipper and
has a separating finger at one end that is inserted between the profiles to force
them apart as the slider is moved along the zipper in an opening direction. The other
end of the slider is sufficiently narrow to force the profiles into engagement and
close the zipper when the slider is moved along the zipper in a closing direction.
[0005] In the past, many interlocking closure strips were formed integrally with the bag
making film, for example, by extruding the bag making film with the closure strips
formed on the film. Such constructions, however, were limited by the conditions required
to extrude both the film and zipper together. To avoid such limitations, many bag
designs entail separate extrusion of the closure strips, which are subsequently joined
to the bag-making film, for example, by conduction heat sealing. These separate closure
strips typically have flanges extending therefrom in such a way that the flanges can
be joined to bag-making film in order to attach the closure strips to the film. Previous
slider-operated, separately extruded zippers used flange-type constructions.
[0006] An alternative zipper design is the so-called flangeless or string zipper, which
has substantially no flange portion above or below the interengageable closure profiles.
In the case of a string zipper, the bag-making film is joined to the backs of the
bases of the closure strips. String zippers can be produced at much greater speeds,
allow much greater footage to be wound on a spool, thereby requiring less set-up time,
and use less material than flanged zippers, enabling a substantial reduction in the
cost of manufacture and processing.
[0007] There is a continuing need for new designs for reclosable bags that can be manufactured
at low cost.
Summary of the Invention
[0008] The present invention is directed to zipper improvements in reclosable packages that
have a slider-operated string zipper attached to a receptacle, the slider being employed
to open or close the string zipper for allowing or denying access to the interior
volume of the receptacle.
[0009] One aspect of the invention is a reclosable package comprising: a receptacle comprising
first and second walls, respective portions of the first and second walls forming
a mouth that communicates with an interior volume of the receptacle; a string zipper
comprising mutually interengageable first and second flangeless zipper strips, the
first flangeless zipper strip having a back joined to the portion of the first wall,
and the second flangeless zipper strip having a back joined to the portion of the
second wall; and a slider mounted over the string zipper to cause the first and second
flangeless zipper strips to separate when the slider is moved in one direction along
the string zipper and to cause the first and second flangeless zipper strips to interengage
each other when the slider is moved in an opposite direction along the string zipper,
the slider comprising first and second sidewalls, the portions of the first and second
walls joined to the first and second flangeless zipper strips passing between the
first and second sidewalls of the slider, wherein the first flangeless zipper strip
comprises a first monohook element, the second flangeless zipper strip comprises a
second monohook element, and the first and second monohook elements interfere with
each other during relative movement of the first and second zipper strips into and
out of interengagement.
Brief Description of the Drawings
[0010] Embodiments of the present invention will now be described in detail with reference
to the accompanying drawings, in which:
FIG. 1 is a drawing showing a reclosable package having a slider-operated string zipper
with end stops;
FIG. 2 is a drawing showing a sectioned view of a slider-string zipper assembly in
accordance with a first embodiment of the present invention, the section being taken
through the zipper at the closing end of the slider [The packaging film is not shown
in section in any drawing to avoid clutter];
FIGS. 3 and 4 are drawings showing respective sectioned views of the string zipper
of the first embodiment at respective stages during a zipper closure operation;
FIG. 5 is a drawing showing a sectioned view of the slider-string zipper assembly
of the first embodiment of the present invention, the section being taken through
the zipper at the opening end of the slider;
FIG. 6 is a drawing showing a sectioned view of a slider-string zipper assembly in
accordance with a second embodiment of the invention, the section being taken through
the zipper at the closing end of the slider;
FIGS. 7-9 are respective drawings showing sectioned views of respective string zippers
in accordance with three variations of a third embodiment of the invention;
FIG. 10 is a drawing showing a sectioned view of a string zipper (attached to walls
of a receptacle) in accordance with a fourth embodiment of the invention;
FIG. 11 is a drawing showing a sectioned view of a slider-string zipper assembly in
accordance with the fourth embodiment, the section being taken through the zipper
at the opening end of the slider;
Detailed Description
[0011] A reclosable package comprising a receptacle 2 and a flexible plastic string zipper
4 operated by manipulation of a slider 10 is shown in FIG. 1. It should be understood
that the slider-zipper assemblies disclosed herein can be installed in a reclosable
package of the type shown in FIG. 1 or other types of reclosable packages having different
structures.
[0012] The receptacle 2 may be made from any suitable film material, including thermoplastic
film materials such as low-density polyethylene, substantially linear copolymers of
ethylene and a C3-C8 alpha-olefin, polypropylene, polyvinylidene chloride, mixtures
of two or more of these polymers, or mixtures of one of these polymers with another
thermoplastic polymer. The person skilled in the art will recognize that this list
of suitable materials is not exhaustive. The thickness of the film is preferably 2
mils or less. The receptacle 2 comprises opposing walls (only the front panel 2a is
visible in FIG. 1) that may be secured together at opposite side edges of the receptacle
by seams 30 and 32 (indicated by dashed lines). The opposing bottoms of the walls
may be joined, for example, by means of a heat seal made in conventional fashion,
e.g., by application of heat and pressure. Typically, however, the bottom of the package
is formed by a fold 34 in the original packaging film, as depicted in FIG. 1.
[0013] At its top end, the receptacle 2 has an openable mouth, on the inside of which is
an extruded plastic string zipper 4. The string zipper 4 comprises a pair of interengageable
zipper strips. One zipper strip 6 is visible in FIG. 1. The profiles of the zipper
strips may take any form. For example, the string zipper may comprise interlocking
rib and groove elements or alternating hook-shaped closure elements or combinations
thereof. The preferred zipper material is polyethylene. The upper margins of the front
and rear bag walls are respectively sealed to the backs of the respective zipper strips
by a conventional conduction heat sealing technique.
[0014] The string zipper is operated by sliding the slider 10 along the zipper strips. As
the slider moves across the zipper, the zipper is opened or closed. As shown in FIG.
1, the slider is slidable along the zipper in a closing direction "C", causing the
zipper strips to become engaged, or in an opening direction "O", causing the zipper
strips to become disengaged.
[0015] The package shown in FIG. 1 further comprises end stops 26 and 28 for preventing
the slider from sliding off the end of the zipper when the slider reaches the zipper
closed or fully opened position. Such end stops perform dual functions, serving as
stops to prevent the slider from going off the end of the zipper and also holding
the two zipper profiles together to prevent the receptacle from opening in response
to stresses applied to the profiles through normal use of the bag. In accordance with
one embodiment of the invention, the end stops comprise stomped areas on the zipper
strips themselves. The stomped end stops comprise sections of the zipper strips that
have been fused together and flattened at the ends of the zipper.
[0016] A string zipper design in accordance with a first embodiment of the present invention
is depicted in FIGS. 2-4. One of the special attributes of the string zipper shown
in FIGS. 2-4 resides in that means are provided for strong resistance to opening from
the inside of the bag. Thus, the upper portion of the string zipper is constructed
and arranged for relatively easy opening from the top, while the lower portion of
the string zipper is constructed and arranged for strong resistance to opening from
the inside of the bag. Also, the zipper design seen in FIGS. 2-4 facilitates alignment
of the zipper strips.
[0017] The profiles of the lower portion of the string zipper 4 are constructed for effectively
resisting opening separation from the interlocking engagement shown in FIG. 2 by separating
forces exerted on the walls 2a and 2b from inside the bag body. The string zipper
comprises first and second flangeless zipper strips 6 and 8. The first flangeless
zipper strip 6 comprises a base 20 and first and second profiled closure elements
22, 24 integrally formed with the base. The first and second profiled closure elements
22, 24 project from one side of the base 20, while a portion of a marginal portion
of wall 2a is joined to the back surface of the base 20, e.g., by conventional conduction
heat sealing in a band-shaped zone of joinder. The second flangeless zipper strip
8 comprises a base 26 and first through third profiled closure elements 28, 30, 32
integrally formed with the base. The first through third profiled closure elements
28, 30, 32 project from one side of the base 26, while a portion of a marginal portion
of wall 2b is joined to the back surface of the base 26, e.g., by conventional conduction
heat sealing in a band-shaped zone of joinder. When the first and second flangeless
zipper strips are mutually engaged, the first profiled closure element 22 of the first
flangeless zipper strip 6 resides in the space between the first and second profiled
closure elements 28, 30 of the second flangeless zipper strip 8, while the second
profiled closure element 24 of the first flangeless zipper strip resides in the space
between the second and third profiled closure elements 30, 32 of the second flangeless
zipper strip.
[0018] In accordance with the embodiment shown in FIGS. 2 and 3, the first profiled closure
element 22 of the first flangeless zipper strip is an elongated rib having a generally
arrowhead-shaped profile. [This rib is a member of the set of elements referred to
hereinafter as "double hook elements", i.e., elements having two hook flanges directed
oppositely.] The rib 22 comprises a head 34 having a generally triangular profile
with a first lateral hook flange or detent 36 along its upper side and a second lateral
hook flange or detent 38 along its lower side. The head 34 is connected to the base
20 by means of a stem 40. The second profiled closure element 24 of the first flangeless
zipper strip 6 comprises an elongated hooked element that is spaced apart from and
extends in parallel with rib 22. [Each hooked element is a member of the set of elements
referred to hereinafter as "monohook elements", i.e., elements having a single hook
flange.] The first and second profiled closure elements 28, 30 of the second flangeless
zipper strip 8 comprise mutually parallel elongated hooked elements respectively located
adjacent to and on opposite sides of the rib 22 when the string zipper is closed.
Hooked element 30 projects from the base 26 of the second flangeless zipper strip
8 and comprises a generally downwardly projecting hook flange or detent 42 on its
distal end that engages the generally upwardly projecting hook flange or detent 36
of the rib 22 of the first flangeless zipper strip 6, while hooked element 28 projects
from the base 26 of the second flangeless zipper strip and has at its distal end a
generally upwardly directed hook flange or detent 44 that engages the generally downwardly
projecting hook flange or detent 38 of the rib 22. The hooked elements 28 and 30 define
a groove within which the head 34 of rib 22 is inserted when the zipper is closed.
[0019] Hook flange 38 of rib 22 is of substantially greater mass, and thus greater stiffness,
than the hook flange 36 of rib 22. The hook flange 44 of the hooked element 28 may
also be provided with substantial mass, so that the engaged hook flanges 38 and 44
afford substantial resistance to separation due to internal forces generated within
the receptacle of the package that tend to push the walls 2a and 2b apart. Further,
to assist in the resistance to internal force separation of the hook flanges 38 and
44, the hooked element 28 has a curved profile, providing a concavity that receives
hook flange 38 of rib 22, so that there is minimum stress tending to separate the
hooked element 28 from the rib 22 when the wall 2b bows outwardly under internal pressure
within the bag. Nevertheless, both of the hooked elements 28 and 30 are relatively
resiliently flexible for enabling their relative movement past head 34 of rib 22 during
zipper closure manipulation. After alignment of the profiled closure elements with
the grooves therebetween as shown in FIG. 3, closing pressure applied from opposite
sides will cause the hook flanges 42 and 44 to cam past the hook flanges 36 and 38
of rib 22 until the hook flanges 42 and 44 clear the hook flanges 36 and 38 and the
resilience of the hooked elements 28 and 30 causes the hook flanges 42 and 44 to snap
into interlocking position behind the hook flanges 36 and 38, as shown in FIG. 2.
[0020] The upper portion of the string zipper 4 comprises a hooked element 32 projecting
from the base 26 of the second flangeless zipper strip 8 and a hooked element 24 projecting
from the base 20 of the first flangeless zipper strip 6. The distal end of hooked
element 32 has a generally downwardly projecting hook flange 46, which engages a generally
upwardly projecting hook flange 48 of hooked element 24. The hooked element 24 is
disposed in back-to-back relation to hooked element 30 in a mutually supportive but
separable relation. In addition, the first flangeless zipper strip 6 also comprises
first and second backup flanges 50, 52 projecting substantially perpendicularly from
the base 20 and respectively overlying the hooked elements 28 and 32 in backup relation.
In effect, the hooked element 24 and the backup flange 52 define a groove that receives
hooked element 32; and the rib 22 and the backup flange 50 define a groove that receives
hooked element 28.
[0021] When maneuvering to close the string zipper 4, the hooked elements 24 and 32 assist
in the zipper closing registration or aligning relation as shown in FIG. 3, at the
same time that the hook flanges 42 and 44 engage in such relation with the head 34
of rib 22. The multiple alignment guidance cooperatively provided by the several hooked
elements of the two sets of profiled closure elements greatly facilitates the zipper
closing procedure. Such closing procedure then continues, as zipper closing pressure
(indicated by mutually opposing arrows 54 in FIG. 4) is applied, by relative flexing
of the flexible profiled closure elements 24, 28, 30, 32, 50 and 52, as indicated
by the solid and dashed line positions in FIG. 4. As the several hook flanges in the
two sets of profiled closure elements pass by one another, the hook flanges of one
set of profiled closure elements snap behind the cooperating hook flanges of the companion
profiled closure elements. Then the multiple flexible elements assume their normal
unflexed positions in the interlocked, i.e., zipper closed, relation as shown in FIG.
2.
[0022] Although the lower portion of the string zipper 4 is so constructed and arranged
that there is efficient, substantially assured resistance against separation due to
internal pressures within the receptacle of the package, and the upper portion of
the string zipper, together with the lower portion will maintain an effective closure
of the receptacle, opening of the receptacle when desired is easily effected by means
of a slider 10, the closing end of which is seen in FIG. 2. Although not seen in FIG.
2, the slider 10 has a separating finger or plow of the type shown in FIG. 5. The
slider is not shown in FIGS. 3 and 4.
[0023] To open the closed string zipper, the slider must be moved in an opening direction.
During slider movement in the opening direction, the separating finger pries the zipper
strips 6 and 8 apart with sufficient force to pull the interengaged profiled closure
elements apart. When the hook flanges of flangeless zipper strip 6 clear the hook
flanges of the second flangeless zipper strip 8, zipper strips are no longer interlocked
and the zipper is open, as seen in FIG. 3.
[0024] As seen in FIG. 2, the slider 10 for opening or closing the reclosable zipper is
generally shaped so that the slider straddles the zipper profiles. The upper margins
of the bag walls 2a and 2b, which are joined to the back sides of the zipper strips
6 and 8, are disposed between the respective zipper strips and the respective side
walls 56 and 58 of the slider. A sealant layer (not shown) may be co-extruded onto
the backs of the zipper strips to facilitate sealing of the bag-making film to the
flangeless zipper strips.
[0025] As seen in FIG. 5 (which shows the opening end of the slider), the slider 10 comprises
a top wall 60, a pair of side walls 56 and 58 connected to opposing sides of the top
wall 60, the top wall 60 and side walls 56, 58 forming a tunnel for passage of the
string zipper therethrough. The slider 10 further comprises a plow 62 depending from
a central portion of the top wall 60 and dividing the slider tunnel into two channels,
one for each zipper strip. The ends of the slider are open to allow the zipper to
pass through. The width of the tunnel is substantially constant along the section
that is divided by the plow 62 and then narrows from a point proximal to the end of
the plow to the closing window at one end face of the slider. The narrowing section
of the tunnel is formed by a pair of substantially planar, inclined interior surfaces
(not shown in FIG. 5), which converge toward the closing window of the slider. These
inclined surfaces cam or squeeze the zipper strips toward each other, causing the
zipper profiles to interlock, as the slider is moved in the closing direction along
the zipper. Retaining projections 64 and 66 project from the side walls 56 and 58
of the slider 10 and extend toward each other. These projections help retain the slider
on the zipper.
[0026] The slider may be made in multiple parts and welded together or the parts may be
constructed to be snapped together. The slider may also be of one-piece construction.
The slider can be made using any desired method, such as injection molding. The slider
can be molded from any suitable plastic, such as nylon, polypropylene, polystyrene,
acetal, polyketone, polybutylene terephthalate, high-density polyethylene, polycarbonate,
or ABS.
[0027] A string zipper design in accordance with a second embodiment of the invention is
shown in FIG. 6. This string zipper comprises a pair of flangeless zipper strips 6
and 8, each of which is an extruded plastic part having a generally constant profile
along its length. The backs of the flangeless zipper strips 6, 8 are joined to the
marginal portions of respective walls 2a, 2b (shown in part) of a receptacle, and
a slider 10 having a separating finger or plow (not shown) will be mounted to the
string zipper with the joined portions of the receptacle walls 2a, 2b passing between
the slider sidewalls 56 and 58.
[0028] The zipper strip 6 comprises a base 82 and first and second hooked elements 84 and
86 projecting from that base, each hooked element having a respective hook flange
or detent 88 and 90 at its distal end. The zipper strip 8 comprises first and second
hooked elements 70 and 72 projecting from the bottom and top respectively of a base
68. The hook flanges 88, 90 of hooked elements 84, 86 project away from each other;
the hook flanges 74, 76 of hooked elements 70, 72 project toward each other. When
the string zipper is closed (as depicted in FIG. 6), the hooked elements 84 and 86
of zipper strip 6 are disposed between the hooked elements 70 and 72 of zipper strip
8 in interengaging relationship. The engagement of hook flange 88 with hook flange
76 and of hook flange 90 with hook flange 74 clasps the zipper strips in interlocking
relationship.
[0029] The flangeless zipper strip 6 shown in FIG. 6 also comprises first and second backup
flanges 50 and 52 projecting substantially perpendicularly from the opposing ends
of the base 82 and respectively overlapping the hooked elements 70 and 72 of zipper
strip 8 in backup relation. The hooked element 84 and the backup flange 52 define
a groove that receives the hooked element 72 of the flangeless zipper strip 8; and
the hooked element 86 and the backup flange 50 define a groove that receives the hooked
element 70 of flangeless zipper strip 8.
[0030] The zipper design shown in FIG. 6 is provided with a self-alignment features in the
form of a large centrally located rib 80 that projects from the base 68 of flangeless
zipper strip 8 into a channel 78 defined by the backs of hooked elements 84 and 86
of flangeless zipper strip 6. The rib 80 has tapered side surfaces. Likewise the channel
78 has tapered surfaces. Alignment of the flangeless zipper strips as they are pressed
together is facilitated by the rib 80 interacting with the sides of the channel 78.
The rib 80 is sized and shaped to fit snugly in the channel 78 during zipper closure.
As a result, the rib's tapered surfaces abut against the hooked elements 84 and 86
so as to prevent inadvertent opening of the zipper.
[0031] Different variations of a string zipper design in accordance with a third embodiment
of the invention are shown in FIGS. 7-9. Again each string zipper comprises a pair
of flangeless zipper strips 6 and 8, each of which is an extruded plastic part having
a generally constant profile along its length. The backs of the flangeless zipper
strips 6, 8 are joined to marginal portions of respective walls (not shown in FIGS.
7-9) of a receptacle, and a slider (also not shown) having a separating finger or
plow will be mounted to the string zipper.
[0032] In each of the variations depicted in FIGS. 7-9, the zipper strip 6 comprises a base
96 and first and second hooked elements 98 and 100 projecting from that base, each
hooked element having a respective hook flange or detent 102 and 104 at its distal
end. The zipper strip 8 comprises first and second hooked elements 112 and 114 projecting
from the bottom and top respectively of a base 110, each hooked element having a respective
hook flange or detent 116 and 118 at its distal end. The hook flanges 102, 104 of
hooked elements 98, 100 project away from each other; the hook flanges 116, 118 of
hooked elements 112, 114 project toward each other. When the string zipper is closed
(as depicted in each of FIGS. 7-9), the hooked elements 98 and 100 of zipper strip
6 are disposed between the hooked elements 112 and 114 of zipper strip 8 in interengaging
relationship. The engagement of hook flange 102 with hook flange 116 and of hook flange
104 with hook flange 118 clasps the zipper strips in interlocking relationship. The
flangeless zipper strip 6 shown also comprises first and second backup flanges 106
and 108 projecting substantially perpendicularly from the opposing ends of the base
96 and respectively overlapping the hooked elements 112 and 114 of zipper strip 8
in backup relation. The hooked element 98 and the backup flange 106 define a groove
that receives the hooked element 112 of the flangeless zipper strip 8; and the hooked
element 100 and the backup flange 108 define a groove that receives the hooked element
114 of flangeless zipper strip 8.
[0033] Each of the zipper designs shown in FIGS. 7-9 is further provided with a feature
for providing improved waterproofing and more effective sealing of the package. The
feature consists of a spreader, projecting from the base of one zipper strip, that
fits between and spreads the hooked elements on the other zipper strip, thereby bringing
the zipper strips into a more positive interlocked condition. More specifically, zipper
strip 8 of the variation shown in FIG. 7 comprises a spreader in the form of a wedge120
having a triangular profile. When the zipper strips 6 and 8 are interlocked, the wedge
120 spreads the hooked elements 98 and 100 of zipper strip 6 apart to bring them into
a more positive interlocked condition with the hooked elements 112 and 114 of zipper
strip 8. In accordance with an alternative variant, a split wedge could be provided
by forming a slot that would extend from the apex of the triangle toward the base
of the zipper strip 8. This split wedge, due to its reduced mass, may be susceptible
to fewer problems during the extrusion process.
[0034] The variation shown in FIG. 8 differs from that shown in FIG. 7 only in that the
spreader 122 has a trapezoidal profile instead of a triangular profile. The profile
of the spreader may alternatively have a curved (e.g., semi-circular or semi-elliptical)
contour.
[0035] In both of the variations depicted in FIGS. 7 and 8, the base of the spreader is
integrally formed with the base of zipper strip 8. In accordance with alternative
variations (not shown in the drawings), a triangular or trapezoidal spreader can be
connected to the base of zipper strip 8 by means of a stem. FIG. 9 shows a variation
wherein the spreader 124 has a circular profile and is connected to the base 110 of
zipper strip 8 by means of a stem 126. The diameter of the spreader 124 needs to be
greater than the width of the gap between the backs of the hooked elements 98 and
100 of zipper strip 6. As a result, when the zipper is closed, the diametrally opposed
portions of the circular cylindrical spreader 124 will bear against the backs of the
hooked elements 98 and 100 of zipper strip 6, causing them to spread apart and into
more positive engagement with the corresponding hooked elements 112 and 114 of zipper
strip 8.
[0036] FIGS. 10 and 11 show a fourth embodiment of the invention. The string zipper consists
of a pair of flangeless zipper strips 6 and 8 that each comprise a pair of profiled
closure elements that are angled relative to the backs of the zipper strips. As seen
in FIG. 10, a flangeless zipper strip 6 comprises a base 130 with first and second
hooked elements 132 and 134 and a backup element 136 integrally formed therewith and
projecting therefrom, while a flangeless zipper strip 8 comprises a base 138 with
first and second hooked elements 140 and 142 and a backup element 144 integrally formed
therewith and projecting therefrom. The first and second flangeless zipper strips
may have substantially identical profiles, with substantially planar back surfaces
146 and 148 that are mutually parallel. When the hooked elements are interlocked,
the hook flanges lie in a plane that is inclined (i.e., neither parallel nor perpendicular)
relative to the plane of the back surfaces 146 and 148. The hooked elements 132 and
134 of zipper strip 6 define a groove that receives the hooked element 140 of zipper
strip 8, while the hooked element 132 and the backup element 136 of the zipper strip
6 define a groove that receives the hooked element 142 of zipper strip 8. Similarly,
the hooked elements 140 and 142 of zipper strip 8 define a groove that receives the
hooked element 132 of zipper strip 6, while the hooked element 140 and the backup
element 144 of zipper strip 8 define a groove that receives the hooked element 134
of zipper strip 6.
[0037] The package in accordance with the fourth embodiment further comprises a slider 10'
(shown in FIG. 11) having an angled separating finger or plow 150 (meaning that plow
150 is not perpendicular to slider top wall 60) for prying the interlocked zipper
strips apart when moved in an opening direction. The sidewalls 56 and 58 squeeze the
zipper strips together when the slider is moved in a closing direction. The angle
of the plow 150 preferably matches the angle of inclination of the hook flanges. The
slider is retained on the string zipper with the aid of retaining projections 64 and
66 projecting from the bottom marginal portions of sidewalls 56 and 58. Respective
marginal portions of walls 2a and 2b are respectively joined to the vertical back
surfaces 146 and 148 (and not to the slanted back surfaces 150 and 152), such joined
marginal portions passing between the slider sidewalls. Joinder to the vertical surfaces
only creates more of a hinge effect when the bag film 2a and 2b moves outward, thereby
improving resistance to opening the zipper from the inside of the bag.
[0038] While the invention has been described with reference to preferred embodiments, it
will be understood by those skilled in the art that various changes may be made and
equivalents may be substituted for members thereof without departing from the scope
of the invention. In addition, many modifications may be made to adapt a particular
situation to the teachings of the invention without departing from the essential scope
thereof. For example, the zipper strips and frangible connection need not be extruded
from the same plastic material. More specifically, the connection could be made of
a material that is more brittle than the material used to form the zipper strips.
Therefore it is intended that the invention not be limited to the particular embodiment
disclosed as the best mode contemplated for carrying out this invention, but that
the invention will include all embodiments falling within the scope of the appended
claims.
[0039] As used in the claims, the term "package" includes bags, pouches, and any other type
of packaging in which a flexible plastic zipper can be incorporated. As used in the
claims, the verb "joined" means fused, bonded, sealed, adhered, etc., whether by application
of heat and/or pressure, application of ultrasonic energy, application of a layer
of adhesive material or bonding agent, interposition of an adhesive or bonding strip,
etc. As used in the claims, the term "string zipper" means a zipper comprising two
interengageable zipper strips that have substantially no flange portions. As used
in the claims, the term "monohook element" means a hook element having a single hook
flange; the term "double hook element" means a hook element having two hook flanges
directed oppositely; and the term "backup element" means an element not having any
hook flanges.
1. A reclosable package comprising:
a receptacle comprising first and second walls, respective portions of said first
and second walls forming a mouth that communicates with an interior volume of said
receptacle;
a string zipper comprising mutually interengageable first and second flangeless zipper
strips, said first flangeless zipper strip having a back joined to said portion of
said first wall, and said second flangeless zipper strip having a back joined to said
portion of said second wall; and
a slider mounted over said string zipper to cause said first and second flangeless
zipper strips to separate when said slider is moved in one direction along said string
zipper and to cause said first and second flangeless zipper strips to interengage
each other when said slider is moved in an opposite direction along said string zipper,
said slider comprising first and second sidewalls, said portions of said first and
second walls joined to said first and second flangeless zipper strips passing between
said first and second sidewalls of said slider,
wherein said first flangeless zipper strip comprises a first monohook element, said
second flangeless zipper strip comprises a second monohook element, and said first
and second monohook elements interfere with each other during relative movement of
said first and second zipper strips into and out of interengagement.
2. The package as recited in claim 1, wherein said first flangeless zipper strip further
comprises a first backup element, said first backup element and said first monohook
element defining a first groove therebetween, said first groove receiving a portion
of said second monohook element when said first and second zipper strips are interengaged.
3. The package as recited in claim 1, wherein said second flangeless zipper strip further
comprises a third monohook element, said second and third monohook elements defining
a first groove therebetween, said first groove receiving a portion of said first monohook
element when said first and second zipper strips are interengaged.
4. The package as recited in claim 3, wherein said first flangeless zipper strip further
comprises a double hook element, said second flangeless zipper strip further comprises
a fourth monohook element, and said third and fourth monohook elements define a second
groove therebetween, said second groove receiving a portion of said double hook element
when said first and second zipper strips are interengaged.
5. The package as recited in claim 3, wherein said second and third monohook elements
comprise respective hook flanges that project in substantially the same direction,
while said first monohook element comprises a hook flange that projects in a generally
opposite direction.
6. The package as recited in claim 1, wherein said first flangeless zipper strip comprises
a third monohook element, said second flangeless zipper strip comprises a fourth monohook
element, and said third and fourth monohook elements interfere with each other during
relative movement of said first and second zipper strips into and out of interengagement.
7. The package as recited in claim 6, wherein said first and third monohook elements
are disposed between said second and fourth monohook elements.
8. The package as recited in claim 6, wherein said second and third monohook elements
comprise respective hook flanges that project in generally the same first direction,
whereas said first and fourth monohook elements comprise respective hook flanges that
project in generally the same second direction, said second direction being opposite
to said first direction.
9. The package as recited in claim 6, wherein said first flangeless zipper strip further
comprises first and second backup elements, said first backup element and said first
monohook element defining a first groove therebetween, said first groove receiving
a portion of said second monohook element when said first and second zipper strips
are interengaged, and said second backup element and said third monohook element defining
a second groove therebetween, said second groove receiving a portion of said fourth
monohook element when said first and second zipper strips are interengaged.
10. The package as recited in claim 6, wherein said first and third monohook elements
comprise respective hook flanges that project in generally the same first direction,
whereas said second and fourth monohook elements comprise respective hook flanges
that project in generally the same second direction, said second direction being opposite
to said first direction.
11. The package as recited in claim 6, wherein said slider comprises a top wall connected
to said first and second sidewalls, and a plow having one end connected to said top
wall, said plow being inclined at an angle relative to said top wall that is not a
right angle.