U.S. patent application number 10/826997 was filed with the patent office on 2004-10-21 for resealable container with magnetic closure system.
Invention is credited to Metzler, Steven Paul, Stanton, Mark Anthony.
Application Number | 20040206638 10/826997 |
Document ID | / |
Family ID | 21937504 |
Filed Date | 2004-10-21 |
United States Patent
Application |
20040206638 |
Kind Code |
A1 |
Metzler, Steven Paul ; et
al. |
October 21, 2004 |
Resealable container with magnetic closure system
Abstract
A container body with a container opening and a flap partially
secured to the container body and completely covering the container
opening is disclosed. The flap is secured to the container by a
hinge or fold line and formed from the same substrate as the
container body. The container body contains a first magnetic region
adjacent to and surrounding the perimeter of the container opening.
The flap contains a second magnetic region aligned with and
opposite the container body's first magnetic region. The first and
second magnetic regions are magnetically attracted to each other.
The flap is held in a closed position by magnetic attraction
between the flap's magnetic region and the container body's
magnetic region.
Inventors: |
Metzler, Steven Paul;
(Covington, VA) ; Stanton, Mark Anthony; (Louisa,
VA) |
Correspondence
Address: |
DONALD L. BOWMAN, ESQ.
WESTVACO CORPORATION
11101 JOHNS HOPKINS ROAD
LAUREL
MD
20723
US
|
Family ID: |
21937504 |
Appl. No.: |
10/826997 |
Filed: |
April 17, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10826997 |
Apr 17, 2004 |
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10045371 |
Jan 15, 2002 |
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6749551 |
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Current U.S.
Class: |
206/1.5 ;
206/818 |
Current CPC
Class: |
B65D 2313/04 20130101;
B65D 5/721 20130101 |
Class at
Publication: |
206/001.5 ;
206/818 |
International
Class: |
B65D 083/10; B65D
075/00 |
Claims
1. A container blank comprising: a plurality of fold lines; at
least one aperture; at least one flap aligned with a larger than
said aperture; a first magnetic region secured around the perimeter
of and adjacent to said at least one aperture; and a second
magnetic region secured around the perimeter of said flap and
opposite said first magnetic region, wherein said second magnetic
region is aligned with and has a magnetic attraction to said first
magnetic region.
2. A container comprising: a body a top section, and a bottom
section, wherein said container at least one aperture; wherein a
first magnetic region is secured to said container adjacent to the
perimeter of said at least one aperture; and at least one flap
secured to said container and covering said at least one aperture
wherein the perimeter of said at least one flap has a second
magnetic region opposite said first magnetic region wherein said
second magnetic region is aligned with and has a magnetic
attraction to said first magnetic region.
3. The container of claim 2, wherein the interior of said container
body and said flap has a polymeric coating.
4. A method of forming a container comprising the steps of:
providing a substrate; cutting said substrate to form at least two
side panels, two end panels; at least one glue panel extending from
at least one end panel, at least two top panels, at least one
bottom panel, and a plurality of dust panels secured to said
plurality of top and bottom panels; forming an aperture in on a
first top panel; forming a moveable flap on a second top panel
wherein said moveable flap is aligned with and larger than said
aperture; securing a first ferrite material around the external
perimeter of said aperture on the external side of said container;
securing a second ferrite material around the interior perimeter of
said moveable flap and on the opposite side of the substrate from
said first ferrite material; generating a first magnetic field in
said first ferrite material; generating a second and opposite
magnetic field in said second ferrite material: forming fold line
between said plurality of panels; folding said plurality of panels
to form a container wherein said moveable flap is aligned with and
covers said aperture in a closed position and wherein said second
ferrite material is secured to said first ferrite material by
magnetic attraction.
5. The method of claim 4, wherein said first and second ferrite
materials are formed from non-polarized gaskets.
6. The method of claim 4, wherein said first and second ferrite
materials are formed from ink containing metallic particles.
7. The method of claim 6, wherein said ferrite materials are formed
by printing said ink and passing the printed substrate through one
or more nips formed between hard rolls covered with a release
coating, wherein said ink is in a plastic state when passing
through the nips.
8. The method of claim 7, wherein said hard rolls are constructed
from a ferromagnetic material and are provided with electromagnetic
coils to generate a strong magnetic field oriented normal to the
plane of said substrate so as to induce a degree of magnetic
anisotropy within said ferrite materials, thus enhancing their
magnetic properties.
9. (Cancelled in Parent 10/045,371)
10. (Cancelled in Parent 10/045,371)
11. A method of forming a container comprising the steps of:
providing a substrate; cutting said substrate to form at least two
side panels, two end panels; at least one glue panel extending from
at least one end panel, at least two top panels, at least one
bottom panel, a least one moveable flap, and a plurality of dust
panels secured to said plurality of top and bottom panels; forming
an aperture on a first end panel; forming a moveable flap from said
substrate wherein said moveable flap is aligned with and larger
than said aperture; securing a first ferrite material around the
external perimeter of said aperture on the external side of said
container; securing a second ferrite material around the interior
perimeter of said moveable flap and on the opposite side of the
substrate from said first ferrite material; generating a first
magnetic field in said first ferrite material; generating a second
and opposite magnetic field in said second ferrite material:
forming fold line between said plurality of panels; folding said
plurality of panels to form a container wherein said moveable flap
is aligned with and covers said aperture in a closed position and
wherein said second ferrite material is secured to said first
ferrite material by magnetic attraction.
12. A method of forming a magnetized article comprising the steps
of: providing a substrate; and securing at least one ferrite
material on at least some portion of the substrate.
13. The method of claim 12 wherein said ferrite material is a
non-polarized gaskets.
14. The method of claim 12 wherein said ferrite material comprises
an ink with at least some metallic particles.
15. The method of claim 14 wherein said ferrite material comprises
iron.
16. The method of claim 12 wherein a magnetic field is generated in
said ferrite material after it is secured to said substrate.
17. The method of claim 12 wherein a magnetic field is generated in
said ferrite material before it is secured to said substrate.
18. The method of claim 12 wherein a magnetically receptive
material is secured to at least some portion of said substrate.
19. The method of claim 18 wherein said substrate is formed into a
container.
20. The method of claim 13 wherein said ferrite material is secured
to said substrate by adhesive means.
21. The method of claim 14 wherein said ferrite materials are
secured to said substrate by a printing means.
22. A method of forming a container comprising the steps of:
providing a substrate; manipulating said substrate to form at least
two or more panels of a container; securing a ferrite material on
at least some portion of said substrate; securing a magnetically
receptive material on at least some portion of said substrate;
generating a magnetic field in said ferrite material; manipulating
said two or more panels to form a container wherein said ferrite
material is secured to at least some portion of said magnetically
receptive material by magnetic attraction.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates to a structure and method of
fabricating a resealable container with a magnetic closure
system.
[0002] Containers store, retain and preserve numerous products.
Containers are made from a variety of materials and are formed into
many shapes and sizes. An exemplary conventional container is a
cereal box made from paperboard. Generally, after placing a product
in a container the container is closed. Containers designed for
"one time" use generally do not have a re-closure system. However
containers that dispense a product at intermittent intervals, such
as cereal boxes, generally require a re-closure system.
Conventional re-closure systems include an arrangement of opposing
flaps on the container, for example at the top of a container. In a
"tab and slot" system a tab extending from a first flap of the
container is tucked into a slot located on an opposing flap. The
tab and slot secure the opposing flaps in a closed position.
[0003] The aforementioned conventional container "tab and slot"
re-closure system works well mechanically so long as the initial
opening of the container does not tear or deform the container
flaps or tab. The ease of initially opening the container depends
upon the strength of the bonds that holds the opposing container
flaps together. Conventionally, opposing flaps are secured to each
other by various adhesive compounds. The type and amount of
adhesive used is chosen to balance the strength of the container's
initial seal with the ease of initially separating the opposing
flaps from each other. A major deficiency with the conventional
"tab and slot" re-closure system is that after opening, the
re-closure system does not provide an acceptable container barrier,
especially for food or perishables items.
[0004] To address this shortcoming, perishable items are
conventionally placed in a in an air, moisture, and vermin barrier,
hereinafter referred to as "membrane." The membrane is vacuum
sealed before the container is closed. For example, food products,
such as cereal, crackers, biscuits, and cookies are conventionally
sealed in a separate membrane before the container is initially
sealed. The membrane serves to protect the product prior to the
initial opening of the container and provides additional barrier
protection after the container is open. Membrane materials
typically comprise plastic, foil, or paper that has been laminated
or coated to produce the desired barrier properties, such as air,
moisture, and vermin control.
[0005] The integrity of the membrane and the available time
interval for safely consuming the membrane's product depends
directly upon the care with which the membrane was initially opened
as well as the care with which the membrane is re-closed after each
opening. A typical membrane is re-closed by rolling the membrane
from the top until the roll is tight against the product.
Additional methods include clipping or otherwise securing the
rolled up membrane to eliminate unrolling. A main disadvantage of
the "rolling" method is that it requires attention and care by the
user. In addition, the rolling method often fails to produces an
adequate seal for perishable products even when the user rolls
according to best practice. In sum, conventional membrane
re-closure techniques do not adequately protect perishable
products. As a result the available consumption time for a product
is not maximized.
[0006] A variety of other container re-closure systems exist. They
can be classified into four general categories: (1) zippers, (2)
pinching aids such as metallic ties and plastic clips, (3) spouts
of various sorts including folding, pullout, and screw-top types,
and (4) various closure flap retention systems. Zippers generally
include a design where a container has an integrated zipper
re-closure system formed in either the container or membrane.
Pinching aids are conventional devices typically applied to the
container flaps and/or membrane. An exemplary use of a pinching aid
is to secure the rolled up portion of a membrane. Container spout
designs include the use of paperboard or plastic elements secured
to both containers and/or membranes that aid in removing the
product from the container and can be repositioned to cover a
container opening.
[0007] Flap retention systems secure moveable flaps to cover
openings in the container. Conventionally flaps require the use of
pressure sensitive adhesive or magnetic forces to secure the flap
over the opening. An exemplary flap adhesive re-closure system is
addition, the adhesive flap re-closure system requires care and
attention by the user to properly secure the flap against the
container.
[0008] An exemplary magnetic re-closure system is disclosed in U.S.
Pat. No. 4,738,390 by Gerald Brennan, entitled "Magnetic Closure
Device For Envelope or the Like." A second exemplary magnetic
re-closure system is disclosed in U.S. Pat. No. 3,749,301 by George
Pecker, entitled "Magnetically Sealable Container." Finally a third
exemplary magnetic closure system is disclosed in U.S. Pat. No.
5,505,305 by Matthew Scholz, et. al., entitled "Moisture-Proof
Resealable Pouch and Container." The three examples each rely on
magnetic attractive forces to secure a "flap-like" article to the
container. However these conventional magnetic re-closure systems
either fail to provide a secure container barrier for perishable
items or require the use of a membrane in addition to the magnetic
closure system to obtain acceptable product protection.
[0009] In summary, conventional container re-closure systems do not
achieve an easy, low cost, and reliable re-closure system. As a
result containers with conventional re-closure systems fail to
provide an optimum air, moisture, and vermin barrier. In addition,
adding a conventional membrane internal to the container to improve
product protection results in increased packaging costs and fails
to optimize product protection.
[0010] What is needed is a container with a re-closure system that
provides an improved container seal after initial opening that is
easy to open and close, is low cost, reliable, and requires little
attention from the user. In addition, what is needed is a container
with a re-closure system that eliminates the need and cost of an
internal membrane.
SUMMARY OF INVENTION
[0011] The invention fulfills these needs not met by the prior art
by providing a re-closure system for a container that is easy to
open and close, reliable, and provides an air, moisture, and vermin
barrier superior to that offered by a conventional membrane and
container system.
[0012] In general, the invention includes a container body with at
least one opening. A flap is partially secured to the container
body and completely covers the container opening. The flap is
secured to the container by a hinge or fold line and formed from
the same substrate as the container body. The container body
contains a first magnetic region adjacent to and surrounding the
opening. The flap contains a second magnetic region aligned with
and opposite the container body's first magnetic region. The first
and second magnetic regions are magnetically attracted to each
other.
[0013] The contents of the container are removed by moving the flap
to an open position. The container product is not placed in a
membrane. The container is re-closed by returning the flap to a
closed position. The flap is held in a closed position by magnetic
attraction between the flap's magnetic region and the container
body's magnetic region. The magnetic force is provided by forming
active magnetic zones on both the container body and flap, or
alternatively, one magnetic zone and a magnetically receptive zone
arranged on the opposing part. The magnetic zones are dimensioned
to extend around the entire border or perimeter of the opening and
at optimized width to provide a good barrier seal.
[0014] In a first exemplary embodiment, magnetic gaskets cut from
commercially available flexible magnetic sheet are secured to the
container body and flap in the desired pattern and location. The
magnetic gaskets are then polarized to create magnetically
attractive regions.
[0015] In a second exemplary embodiment, magnetic regions are
formed on the flap and container by printing ink containing ferrite
material in the desired pattern and location. The ferrite regions
are then polarized to create magnetically attractive regions.
BRIEF DESCRIPTION OF THE DRAWING
[0016] The above and other features of the present invention which
will become more apparent in the description below, and can be
understood by the following detailed description in conjunction
with the accompanying figures, wherein like characters represent
like parts throughout the several view and in which:
[0017] FIG. 1 is a plan view of a blank for a container with a top
flap according to the invention;
[0018] FIG. 2 is an orthogonal view of a container formed from the
blank of FIG. 1;
[0019] FIG. 3 is a plan view of a second embodiment of a blank
container with a top flap according to the invention;
[0020] FIG. 4 is an orthogonal view of a container formed from the
blank of FIG. 2;
[0021] FIG. 5 is a plan view of a third embodiment of a blank
container with a top flap according to the invention;
[0022] FIG. 6 is an orthogonal view of a container formed from the
blank of FIG. 5;
[0023] FIG. 7 is a plan view of a third embodiment of a blank
container with a top flap according to the invention;
[0024] FIG. 8 is an orthogonal view of a container formed from the
blank of FIG. 7;
[0025] FIG. 9 is a plan view of a blank container with a side flap
according to the invention;
[0026] FIG. 10 is an orthogonal view of a container formed from the
blank of FIG. 9;
[0027] FIG. 11 is a plan view of a second embodiment of a blank
container with a side flap according to the invention; and
[0028] FIG. 12 is an orthogonal view of a container formed from the
blank of FIG. 11;
DETAILED DESCRIPTION OF THE INVENTION
[0029] FIG. 1 illustrates an exemplary container blank or substrate
100 for forming a container 105 (FIG. 2) according to the
invention. In an exemplary embodiment the blank 100 is made from
paperboard or paper. However it is to be understood that the
invention covers a wide range of suitable materials for blank 100
including various plastic compositions and laminates.
[0030] In an exemplary embodiment, blank comprises four bottom
sections, 170, 172, 174, 176, four main body sections 130, 132,
134, 136, and four top sections 150, 152, 153, 154. The blank 100
has a plurality of fold lines 104, 106, 108. The blank 100 sections
are folded and cut to form container 105 (FIG. 2). Glue flap 160 is
one means to secure the folded main body sections 130, 132, 134 in
the shape of a conventional container shape. Bottom sections 170,
172, 174, 176 and top sections 150, 152, 153, 154 are cut and
folded to form a closeable top and bottom for the container 105.
Top section 153 provides a glue flap to provide integrity to the
container.
[0031] An aperture 140 is formed in the top section 152 of the
blank 100 using conventional techniques. A first ferrite or
magnetic region 156 is formed on the perimeter and adjacent to
aperture 140. The method of forming the ferrite or magnetic regions
will be discussed below. An exemplary flap 120 is formed in a top
section 150 of blank 100. The flap is formed by making cuts along
section 150 using conventional methods. A second ferrite or
magnetic region 126 is formed on a side of flap 120 opposite the
first ferrite region 156. Flap 120 is shown with optional tab 122
to assist with opening and closing the container 105 via the flap
120. The tap 122 can be formed from cutting a portion of the blank
100 using conventional methods. The container 105 of FIG. 2 can be
formed using the blank of FIG. 1 using conventional techniques well
known in the art.
[0032] If container 105 stores perishable items such as breakfast
cereal, then the re-closure system (flap and opening with first and
second magnetic region) must be arranged or dimensioned to provide
adequate barrier properties, such as moisture, air, and vermin
barriers for the container 105. By properly designing the ferrite
or magnetic regions, the conventional membrane for the perishable
products can be eliminated. In an exemplary embodiment, the blank
100 for the container 105 is coated with polymeric material to
create the desired barrier properties. Exemplary coatings include
extrusion coating of various polyethylenes onto the side of the
blank 100 which will form the interior of the container 105. To
protect against tampering with the container 105, the flap 120 can
have a tamper seal or tear off strip (not shown), surrounding the
flap 120 which is broken or removed when the container 105 is
initially opened. Exemplary tamper seals are made from paper or
cellophane, although a wide-range of tamper proof measures are
encompassed by the scope of the invention.
[0033] The formation of the ferrite or magnetic regions,
hereinafter referred to as ferrite regions, may be accomplished by
several exemplary methods. In a first exemplary embodiment, the
ferrite regions are formed from magnetic gaskets to form a
re-closure system as discussed above. The magnetic gaskets are made
from commercially available flexible magnetic sheeting, such as
magnetic sheets made by Plastiform Division of Arnold Engineering.
Magnetic sheets of this type are conventionally used for magnetic
tags, signs, "refrigerator magnets," and the like. The magnetic
sheets are pre-cut prior to placement on the blank 100 to the
desired shape and size. The magnetic gaskets are then bonded to the
flap or container blank using a conventional labeling machine
adapted for this purpose.
[0034] Various types of labeling equipment are used in the
packaging industry to apply labels to almost any type container,
with a high degree of placement accuracy and at production rates of
many thousands of containers/hour. The magnetic gaskets may have
pre-applied pressure sensitive adhesive ("PSA") or a gluer can be
used to apply adhesive, in the desired pattern, to each container
blank. Application of the magnetic gaskets may be applied "inline"
on the same continuous production line that prints, cuts, and
scores the base substrate web in form to produce individual carton
blanks.
[0035] According to this embodiment the magnetization pattern
(spatial extent of the zonal bands of magnetization and their
polarity) are exactly the same for the flap magnetic strip and the
container opening magnetic strip. For example, if spatial
arrangement of the opposing magnetic gaskets is exactly the same
but with opposite magnetic polarity, the magnetic force produced
between the flap and the container will be repulsive rather than
attractive. Thus, maximum attractive force between the flap and
container will be produced only if the magnetization zonal patterns
of the two regions are "in register" and aligned.
[0036] In order to achieve accurate magnetic register with stacked
blanks, and also to avoid possible production problems, such as
feeding problems, i.e., two or more container blanks sticking
together, prior to the cartons erection and filling, magnetization
of the magnetic gaskets may be done on the container filling line
itself Accurate magnetic pole registration is possible on a carton
filling line by using a jig that keys in, or counter-fits to the
external contour of the carton blank to precisely locate and align
the blank relative to the magnetizing fixture. The magnetizing
fixture poles (assuming a linear magnetization pattern) are either
exactly parallel or perpendicular to the folding axis of the
closure flap. For cartons made from a single blank whose closure
flap is directly attached to the body of the carton by a
score-fold, the latter orientation will in practice yield the most
consistent result, as the effect of small flexional displacements
at the folding score is thus obviated.
[0037] The holding strength of flat, sheet-form magnets is a
function of the number of poles-per-inch of the magnetization
pattern, where a fine pattern (having a large number of poles/inch)
increases the holding strength of a magnet, all else (magnet
composition and thickness) equal. Choice of a poles/inch value for
a magnetic closure will thus be a tradeoff between a desirable high
holding strength and the degree to which it is possible to maintain
magnetic register. A value of.about.10-12 poles/inch should strike
a satisfactory balance, and this value is in fact within a range
conventionally used. State of the art magnetizers currently can
have up to 18 poles/inch, and 50 poles/inch is said to be
attainable. This latter value suggests an alternative approach to
achieving magnetic polar register.
[0038] Two sheet-type magnets that are magnetized at 50 poles/inch
will re-establish register each time they are displaced relative to
each other by {fraction (1/25)}th of an inch in a shearwise fashion
(and in a direction perpendicular to their lines of polarization).
If the hinge point between the closure flap and carton is made
flexible and compliant, the flap will automatically position itself
so that its magnetization pattern is in register with that of the
carton. One embodiment of this approach for a paperboard container
would be to have a separate closure flap joined to the container
via a strip of polymeric material in thin sheet form, such as any
type plastic film conventionally used to make so-called flexible
packaging, i.e.; polyethylene. Now, the most advantageous
orientation of a (linear) magnetization pattern on the flap and
container would be to have the lines parallel to the folding axis
Then, width of the film that bridges the gap between the flap and
container to form a hinge would only need to be on the order of a
small multiple of the {fraction (1/25)} inch "repeat length" just
described--say 0.1 to 0.125 inches For illustration purposes, the
techniques described above yield for a flap design of FIGS. 1 and 2
a tensile opening force (applied to the tab on the end of the flap)
equal to approximately 0.25 lbf. This is enough resistance to
prevent accidental opening due to the weight of the contents,
should the box fall over or be laid down on its side.
[0039] An approach that by-passes the necessity of providing
accurate polar registration between magnetic gaskets upon the
carton body and flap is to magnetize only one of the gaskets. The
opposing non-magnetized gasket is made from a magnetically
receptive material such as "Rubber Steel".RTM. made by Magnum
Magnetics, Inc. A magnetically receptive paint (Magic Wall.TM.
latex) is made by Kling Magnetics, Inc. under license of U.S. Pat.
Nos. 5,609,688 and 5,843,329. From a functional standpoint it does
not matter which surface is magnetically receptive, i.e, the flap
or the container. However, various product promotional purposes,
such as advertisement, collectibles, product data, etc, could be
served if the flap's gasket is magnetized and easily removable. As
previously mentioned, magnetization of a single magnetic gasket
would likely be done later on the filling line, to avoid possible
feeding problems with stacked blanks.
[0040] An alternative to using a polymer-based, flexible magnetic
sheet to form a carton closure is to print magnetic regions
directly onto the container blank. In an exemplary print method,
the ferrite particles are mixed with a binder, which can be a
latex-, oil-, or lacquer-based paint, ink, or coating, for
subsequent printing or coating application to the paperboard.
[0041] Magnetization is then done by conventional means
(application of an external magnetic field of strength sufficient
to align the "domains" of the magnetic filler articles). Strength
of the magnet thus produced is a function of the thickness of the
coated or extruded magnetic layer, magnetic particle packing
density within the binder, and the particular magnetic compound
chosen for use.
[0042] An exemplary magnetic region forming technique is a screen
printing press method. Screen printing has an advantage since the
amount of ink that can be applied in terms of ink deposition
thickness is much greater than other printing processes (e.g.
rotogravure, flexographic, offset lithography). Magnetic holding
strength is known to be a strong function of the volumetric packing
density of ferrite that composes a magnetic layer. Of the three
types (ultraviolet cured, heat cured, and solvent based) ink used
in the experiments, solvent based inks gave the highest volume
fractions of ferrite, and consequent best magnetic performance.
This is first of all because the solvent based ink had a lower
initial viscosity than the other types ink, so that more ferrite
could be mixed with the ink before viscosity of the mixture
increased to a point beyond which printing is possible. Secondly,
and very important, much of the initial volume of the ink is lost
through solvent evaporation: the drying and curing process
effectively acts to concentrate the volume fraction of ferrite in
the printed sayer. An additional process step is necessary,
however, to obtain maximum ferrite packing density. Solvent
evaporation leaves air voids in the ferrite/ink mixture, so it is
necessary to compact the printed layer when it is yet in a
semi-cured, plastic state. This can be done by passing the printed
substarte through one or more lightly loaded (less than 20
kN/meter.about.114 lbf/lineal inch) "nips" formed between hrad
rolls covered with a suitable release-type coating (Teflon.RTM.,
for example). By this means, thickness of a solvent-based, printed
ferrite layer can be decreased (and its density increased) by a
factor of two, and volumetric fractions of ferrite in excess of 75%
can be attained.
[0043] Magnetic properties of the printed layer may be further
enhanced by creating a strong magnetic field within the nip itself,
so as to induce a degree of anisotropy within the magnetic layer (a
purely anisotropic magnet is one whose individual magnetic domains
share a common, parallel orientation). A magnetic field having the
desired orientation (perpendicular to the web) may be created
within the nip zone by constructing the rolls from a ferromagnetic
material (iron or steel, for example), and installing
electromagnetic coils on the side of each roll opposite the nip.
This approach is potentially most advantageous for so-called "high
energy" ferrites, whose individual particles are intentionally made
to be a single magnetic domain--within the industry, this is termed
"uniaxial crystalline anisotropy." The unipolar magnetic field of
each individual particle tends to orient itself parallel to the
field imposed within the roll nip. An additive effect of the roll
nip is its ability to mechanically orient those types ferrite
powder whose particulate morphology is intentionally manipulated
during manufacture to create plate-shaped particles having a length
and width greater than the thickness--fluid shear within the nip
zone acts to mechanically orient the platelike particles parallel
to the plane of the web. Magnetic orientation of these ferrites is
typically made to be normal to the plane of the particle, so the
net (and intended) effect of particle orientation induced by both
magnetic and mechanical means is to create a non-isotropic magnet.
These techniques form part of the conventional art of manufacturing
flexible polymer-based magnets, but are here extended to the
potential production of magnets created by the printing ferrite
ink.
[0044] An exemplary ferrite region was formed using an ink (Coates
Screen Gloss Vinyl C-99 mixing clear) chosen for its high degree of
mechanical flexibility when cured. Weight proportions of six parts
ferrite, one part mixing clear, and 2.4 parts reducer were combined
to make the ferrite ink. The mixing clear contains approximately
70% volatile solvent and 30% binder by weight: the above
proportions provide a mixture that can be printed and cured to
contain at least 75% ferrite by volume. Use of a 60 mesh screen, a
200 micron emulsion, and a 60 durometer squeegee yielded a per pass
dried film thickness of approximately 7 mils after being
consolidated in a roll nip. Ferrite layers 0.014 inches thick were
produced by overprinting (double thickness) and then were
magnetized at 18 poles/inch. Magnetic holding strength was 1.3
ounces/square inch, about 30% that of a typical, 0.020 inch thick
flexible bonded magnet.
[0045] One problem with producing magnetic zones by direct printing
of ferrite ink onto a substrate is the extremely heavy ink
application rate required. A typical ink thickness, or laydown, of
screen printed graphic designs for packaging applications is
.about.0.0005 inches, or {fraction (1/30)} the amount cited above.
This means that drying and curing of a screen printed magnetic
surface is presently a production bottleneck. Even with compact
designs for forced air dryers (vertical units with serpentine web
runs) are available, drying rate limitations inherent to thick
coatings would dictate layers as thick as 0.015 inches would have
to be printed using multiple print stations. Thus direct printing
approaches require expensive dryers and have slow production
rates.
[0046] FIGS. 3 and 4 illustrate another top flap container
arrangement. Blank 200 has two top sections 252, 253 connected by
fold line 260. An aperture 240 is formed in top section 252. A
first magnetic region 256 is formed on top section 252 and a second
magnetic 226 is formed on top section 253. Blank 200 is folded as
described above in FIGS. 1 and 2 to form container 205 (FIG.
4).
[0047] FIGS. 5 and 6 illustrate another top flap container
arrangement. Blank 300 has four top sections 350, 320, 352, 353. An
aperture 340 is formed in top section 352. A first magnetic region
356 is formed on top section 352 and a second magnetic 326 is
formed on flap 320. Blank 300 is folded as described above in FIGS.
1 and 2 to form container 305 (FIG. 6). Flap 320 is connected to
body section 330 along hinge line 370.
[0048] FIGS. 7 and 8 illustrate another top flap container
arrangement. Blank 400 has three top sections 452, 420, 454. An
aperture 440 is formed in top sections 452, 420. A first magnetic
region 456 is formed on top section 420 and a second magnetic 426
is formed on top section 420. Blank 400 is folded as described
above in FIGS. 1 and 2 to form container 405 (FIG. 8). Top section
420 is connected to body section 340 along hinge line 470. Top
section 420 is cut along line 472 to form a flap that covers
aperture 440.
[0049] FIGS. 9 and 10 illustrate a slide flap container
arrangement. Blank 500 has four top sections 550, 520, 552, 554. An
aperture 540 is formed in main body sections 532. A first magnetic
region 556 is formed on main body section 532 and a second magnetic
region 526 is formed on top section 520. The second magnetic region
526 is formed on an opposite side of blank 500 from the first
magnetic region 556. Blank 500 is folded as described above in
FIGS. 1 and 2 to form container 505 (FIG. 10). Top section 552 is
connected to body section 534 along hinge line 546. Top section 520
is cut along line 553 to form a flap 520 that covers aperture 540.
Flap 520 is connected to top section 550 along hinge line 542.
[0050] FIGS. 11 and 12 illustrate a second embodiment of a slide
flap container arrangement. Blank 600 has four top sections 650,
620, 652, 654. An aperture 640 is formed in main body sections 632.
A first magnetic region 656 is formed on main body section 632 and
a second magnetic region 626 is formed on top section 620. The
second magnetic region 626 is formed on the same side of blank 600
as the first magnetic region 656. Blank 600 is folded as described
above in FIGS. 1 and 2 to form container 605 (FIG. 12). Top section
652 is connected to body section 634 along hinge line 646. Top
section 620 is cut along line 653 to form a flap 620 that covers
aperture 640. Flap 620 is connected to top section 650 along hinge
line 642.
[0051] It is to further be understood that the opening, flap, and
magnetic regions of container formed according to the invention can
have numerous arrangements, configurations, designs, locations, and
dimensions within the scope of the invention. In addition the body
of the container and flap can be formed from a single or a
plurality of blanks using techniques well know in the art to form
containers. It is to further be understood that the term ferrite or
magnetic region encompasses a wide range of material capable of
either forming a sufficiently strong magnetic field or being
sufficiently magnetically receptive to allow a sufficiently strong
enough magnetic attraction to form between the flap and the
container body.
[0052] Once given the above disclosure, many other features,
modifications or improvements will become apparent to the skilled
artisan. Such features, modifications or improvements are,
therefore, considered to be a part of this invention, the scope of
which is to be determined by the following claims.
* * * * *