Note: Descriptions are shown in the official language in which they were submitted.
CA 02618440 2008-01-15
LIGHT-BLOCKING PLASTIC BAG
Inventor: Eugene H. Stys
Michael J. Recchia, Jr.
BACKGROUND OF THE INVENTION
Produce is marketed in plastic bags typically having ventilation apertures,
for
ease of their distribution to consumers in supermarkets and the like. However,
particularly with respect to potatoes, they are subject to "greening" when
exposed to
light for even a very few days.
As stated in the article of Alexander D. Pavlista entitled Green Potatoes: the
Problem and the Solution, in the Neb Guide published by the University of
Nebraska,
Lincoln, Nebraska (G1437): "Greening (of potatoes) is strongly affected by the
cumulative effects of light quality, duration, and intensity. Chlorophyll is
green because
it reflects green light while absorbing red-yellow and blue light. Chlorophyll
formation is
most sufficient under red-yellow light. Under green light, practically no
potato greening
occurs and little occurs under blue or ultra-violet lights. Fluorescent lights
induce more
greening than incandescent lights."
"Greening" is undesirable, tending to alter the taste of the potato, and even
creating toxic compounds in the potato. Thus, the greening of potatoes
represents a
significant problem to the industry of produce marketing.
By this present invention, an inexpensive, plastic bag for produce is
provided,
which is usable in automated processes, and which can protect potatoes or
other
produce from the harmful light, while at the same time providing a way for the
consumer
to inspect the produce product within the bag.
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DESCRIPTION OF THE INVENTION
In accordance with this invention, a plastic bag for produce is provided which
comprises first and second plastic walls, peripherally bonded together. A
central plastic
wall is positioned between the first and second plastic walls and peripherally
bonded to
the first and second walls. The central plastic wall is opaque to
substantially block the
passage of light therethrough, although it may comprise a plurality of layers
in which, if
desired, one of such layers is light colored, and another dark colored to
provide the
opaque characteristic.
The plastic bag may initially have an open end to receive produce such as
potatoes. The produce may be inserted into the bag in a compartment defined
between
the second wall and the central, plastic wall, with the first wall being
translucent. This
translucent first wall may carry printing or the like, identifying the brand
and the type of
potatoes in a conventional manner. Because of the design of the bag of this
invention,
it is generally immaterial that the first bag wall is translucent, since the
central, generally
opaque plastic wall can substantially block the passage of light therethrough,
protecting
the produce thereon. This may be accomplished by coloring the plastic wall
black to
provide an opaque characteristic.
Thus, when the produce is placed in the compartment defined between the
second wall and the central plastic wall, the central plastic wall protects
the potatoes or
other produce from light passing through the first plastic sidewall. Then, the
produce-
filled plastic bags are displayed with the first wall up, so that the brand
and description
of the potatoes or other produce on the first wall can be displayed. The
second plastic
wall may also carry printed indicia, but it preferably contains a transparent
window, or
the second wall may be completely transparent, so that the buyer can inspect
the
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_
produce in the bag. However, typically, since the bags are stored with the
first wall
positioned upwardly, little light gets in to irradiate the potatoes or other
produce through
this transparent portion of the second wall.
The central, plastic wall may comprise a light-colored layer facing the first
wall,
and an opaque layer, to substantially block the passage of the light, facing
the second
wall. The purpose of the opaque layer has been described above, i.e. to
prevent light
passing through the first plastic wall from reaching the produce. However, the
opaque
wall, which may be black or of another dark color in some embodiments, can
interfere
with the legibility of the printed identification and display of the package
on the first wall.
Thus, the light-colored layer can serve as a backing, so that the printed
material thereon
is more visible, and any colors used in the printing on the first wall can be
more
impressive.
The light-colored layer and the opaque layer of the central plastic wall can
comprise a co-extrusion, or they may comprise separate sheets, peripherally
joined
together, and/or joined together with seal lines across the layers, or by any
other
bonding technique desired.
The bag can be sealed on all sides except for one end so that, after filling,
one
added bar type heat seal can fully seal the bag. Alternatively, the bag may be
closed
with hog ring or the like, if desired.
Thus, an inexpensive bag, capable of automated production and filling, is
provided, in which produce such as potatoes can be protected from undesired
light
irradiation, to avoid greening in the case of potatoes.
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Also, a method for storing potatoes is provided, which comprises: inserting
the potatoes
into a plastic bag, which bag comprises: first and second plastic walls, and a
central plastic wall
between the first and second walls, the plastic walls being peripherally
bonded together. The
first plastic wall is typically translucent, and the central plastic wall is
opaque, to substantially
block the passage of light therethrough. The method further comprises
enclosing the potatoes in
the plastic bag between the second plastic wall and the central plastic wall,
and storing the
potatoes with the first plastic wall facing upwardly.
The central plastic wall may define a light-colored layer facing the first
wall and a dark-
colored layer facing the second wall as described above, to substantially
block the passage of the
light. Also, in some embodiments, at least a portion of the second plastic
wall is transparent, to
permit viewing of the produce in the bag.
In one broad aspect the invention provides a bag, comprising first and second
walls
peripherally coupled together, a central wall disposed between the first and
second walls and
peripherally coupled to the first and second walls, the central wall being
opaque to substantially
block light from passing through the central wall, and at least a portion of
the second wall is
transparent to allow viewing into the bag.
In a further broad aspect the invention comprehends a method for storing
produce,
comprising inserting the produce into a bag, the bag including first and
second walls and a
central wall disposed between the first and second walls, the first and second
walls being
peripherally coupled together, the central wall being opaque to substantially
block light from
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passing through the central wall, a portion of the second wall being
transparent to permit viewing
of the produce in the bag, enclosing the produce in the bag between the second
wall and the
central wall, and storing the bag with the first wall facing upwardly.
DESCRIPTION OF THE DRAWINGS
In the drawings, Fig. 1 is a front perspective view, with portions broken
away, of a plastic
bag for potatoes of this invention.
Fig. 2 is a rear perspective view of the plastic bag of Fig. 1.
Fig. 3 is an exploded perspective view of the plastic bag of Figs. 1 and 2,
showing the
separate sheets from which the bag may be made by heat sealing in an automated
assembly line.
DESCRIPTION OF SPECIFIC EMBODIMENTS
Referring to the drawings, Fig. 1 shows plastic bag 10 for produce having
first and
second plastic walls 12, 14, peripherally bonded together by heat seal 16, as
shown on three
sides. Initially, fourth side 18 of bag 10 may comprise an open mouth.
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Potatoes 20 may be inserted into bag 10, and then fourth side 18 may also be
sealed,
as is conventional.
As shown, bag 10 also carries a central plastic wall 22 which is also
peripherally
sealed at the mutual seal lines 16 of the respective plastic walls 12, 14, 22,
including
side 18 after loading of potatoes 20 into bag 10, typically after bag 10 has
been sealed
on the first three sides 16.
Thus, it can be seen that bag 10 defines a pair of compartments, one of which
is
the space between walls 12, 22, which is typically empty, and the other of
which
contains the potatoes 20, namely the space between walls 22 and 14.
First plastic front wall 12 can be seen to carry a printed label, a logo 23,
and/or
any other desired advertising indicia for identification of the product. Also,
first plastic
wall 12 may be translucent or even transparent (which is included in the term
"translucent") throughout much of its extent. The surface 24 of central
plastic wall 22,
which faces wall 12, is of a light color, typically white, so that logo 23,
carried on first
plastic wall 12, is readily seen against a light colored background, namely
the white or
other light color surface 24 of central plastic wall 22. This colored surface
may be
printed or otherwise applied to typically transparent plastic of layer 22.
Turning to Fig. 2, it can be seen that the side 30 of central plastic wall 24
that
faces second plastic wall 14 is of a dark, opaque color, for example black
printing ink, or
an opaque pigment layer, carried on central plastic wall 24, as desired. Thus,
central
plastic wall 24 is substantially opaque, and does not transmit much light.
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Central plastic wall 24 may also comprise co-extruded layers of light and dark
plastic, or a pair of separate light and dark plastic sheets, peripherally
joined at seal line
16.
In Fig. 2, a view of bag 10 from its other side is shown, with second plastic
wall
14 being presented forwardly, and first plastic wall 12 being in the rear.
Second plastic
wall 14 may also carry writing or other indicia 26, as well as a viewing
window 28
through which the potatoes 20 can be seen. If desired, viewing window 28 may
be
larger, being in area up to the entire extent of second plastic wall 14.
Thus, when the sealed bags 10, containing potatoes, are stored for example in
a
bin of a supermarket with overhead fluorescent lights irradiating them, they
are stored
with their first side 12 upwardly, for product identification and to attract
consumers. The
light that passes through first plastic wall 12 is at least partially
reflected by light colored
layer 24 of central plastic wall 22, to highlight the logo or other indicia 23
on translucent
first side 12. However, light does not penetrate central plastic wall 22 to
any significant
extent, because of the dark colored, typically black layer 30 on the side of
central wall
22 that faces second wall 14. Thus, the potatoes are in substantial darkness,
since they
are typically stored with transparent window 28 facing downwardly in the
produce bin,
and fluorescent lights above do not significantly effect them. This creates a
significant
increase in the useful life of potatoes 20 as a saleable product, preventing
their
greening.
It can be seen that ventilation holes 32 are provided in the respective first
and
second plastic walls 12, 14, in a conventional manner.
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Thus, a plastic bag is provided in which the lifespan of produce such as
potatoes
can be significantly lengthened, despite the fact that they are displayed for
purchase
under fluorescent lights or other brightly lit conditions, which reduces
product loss by
avoiding the "greening" problem.
The above has been offered for illustrative purchases only, and is not
intended to
limit the scope of the invention of this application, which is as described in
the claims
below.
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