Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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MICROWAVE HEATING OF HEAT-EXPANDABLE MATERIALS
FOR MAKING PACKAGING SUBSTRATES AND PRODUCTS
BACKGROUND
[0001] Consumers frequently purchase ready-made products, such as food and
beverages and other products, in containers made from packaging substrates.
Thermally-insulated containers may be designed for hot or cold liquids or
foods,
such as hot coffee, iced-tea, hamburger, sandwiches, or pizza, so on. It is
desirable
that these containers can maintain the temperature of the liquid or food
contents as
long as possible by reducing heat or cold transfer from the contents through
the
container.
[0002] To help insulate the hand of the consumer from the heat of a
hot
beverage, or keep the desirable temperature of the contents of a food or
beverage
container longer, heat-expandable adhesives and coatings have been developed
by
the inventors for use with packaging substrates, for example, with multilayer
micro-
fluted board, paper or paperboard. Such expandable adhesives and coatings can
expand upon being heated over a range of certain temperatures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0003] Figure 1 is a perspective view of a cup assembled with an outer
wall.
[0004] Figure 2 is a side cutaway view of a double wall cup.
[0005] Figure 3 is a cross-section view of a sleeve with a cup.
[0006] Figure 4 is a side view of an exemplary machine system for
making
packaging materials and substrate for containers.
[0007] Figure 5 is a side view of a vacuum conveyor through which
blanks may
be processed to which is adhered heat-expandable material.
[0008] Figure 6 is a modified mandrel adapted with a raised strip
including
vacuum holes.
[0009] Figure 7 is an example of an outer wall blank (or wrap) having
a
patterned coating of heat-expandable material having a gap into which the
raised
strip of the mandrel of Figure 6 may be located.
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[0010] Figure 8 is a perspective view of a vacuum tube conveyor using
the
mandrel of Figure 6 to transport an outer wrap that includes heat-expanded
particles
on an inner side.
[0011] Figure 9 is a perspective view of a cup-building machine,
showing
application of heat-expandable material to an outside of an inner cup.
[0012] Figure 10 is a perspective view of the cup-building machine of
Figure 9,
showing insertion of the covered inner cup into an out cup blank (or wrap), to
build
a double wall cup.
[0013] Figure 11 is a flow diagram of multiple workstations or points
of a
manufacturing process for manufacturing packaging products, where microwave
heat may be applied at or between these points to expand heat-expandable
adhesives
or coatings incorporated within or on substrate layers of packaging substrates
and/or
product(s).
[0014] Figure 12 is a perspective schematic view of an exemplary
industrial
microwave heater applicator as positioned over conveyor belts.
[0015] Figure 13 is a top, plan schematic view of the microwave heater
applicator of Figure12.
[0016] Figure 14 is a side, plan schematic view of the industrial
microwave
heater applicator of Figure12.
[0017] Figure 15 is a front, cross-section schematic view of the industrial
microwave heater applicator of Figure 12.
[0018] Figure 16 is a flow chart of an exemplary method for
manufacturing a
multilayer sheet material in a process that includes microwave heating of the
multilayer sheet material to expedite expansion of a heat-expandable adhesive
or
coating.
DETAILED DESCRIPTION
[0019] A method is disclosed for utilizing microwave energy to heat,
activate
and expand heat-expandable adhesives and coatings, which can be either onto
and/or
within a substrate material used to subsequently be converted to a product, or
placed
directly onto or within a packaging product during its manufacturing
processes. The
substrate material can be either monolayer or multilayer in the form of rolls,
sheet or
blanks made of materials such as paper, paperboard, coated paper, fluted board
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material, plastic film, woven material, textile, nonwoven material, and/or
metalized
substrates, or any combination of these materials.
[0020] The multilayer sheet or roll web substrates can be bonded
together by
heat-expandable adhesives and coatings. The product can be a variety of
packaging
or non-packaging products, for example, but not limited to, double wall paper
hot
cups, paper bags, clamshell, hot cup insulating sleeves, take-out folding
carton and
boxes. The method may include heating up the packaging products made of such
materials after the products are formed, or after the products are packed in a
shipping container, or after the containers are loaded onto a pallet. A
microwave
heater utilizes microwave energy to activate the heat-expandable adhesive or
coating, causing the heat-expandable adhesive or coating to expand
efficiently. The
expansion of the adhesives or coating can help increase thermal insulation and
rigidity of a laminated or coated material, which helps convert the materials
to
packages or containers, and improve the insulation of the fluid and solid
contents of
the containers. The expansion of the adhesives or coating can also help reduce
packaging material by allowing the use of less material while maintaining the
thermal insulation and rigidity required of a laminated or coated material.
[0021] The method above can be automated to activate and expand the
heat-
expandable adhesives and coatings on or in substrate material (or called the
"pre-
activation") or on or in a product after it is formed (call the "post-
activation"). The
heat-expandable adhesive or coating may be formulated with a composition
containing heat-expandable microencapsulated particles, like microspheres or
microtubes or other shapes, and other components, such as starch or other
natural or
synthetic binders and other additives as needed for a specific application.
For
example, the heat-expandable adhesive or coating may be prepared within one or
a
combination of: viscosity modifier, moisture modifier, defoamer, dispersants,
anti-
mold agents, and salts. Some examples of a microencapsulated particle include:
Dualite supplied by Henkel, Expancel supplied by AkzoNobel, the Microspheres F
and FN series supplied by Matsumoto, and the Microspheres supplied by Kureha.
[0022] The microwave heater may heat the material at any of various points
of
the manufacturing process after the application of the heat-expandable
adhesive or
coating. A multilayered sheet material may be laminated with any combination
of
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suitable materials aforementioned, and conveyed to final processing, such as
to be
printed, die cut, formed, and/or otherwise assembled into product containers.
[0023] Heat may be applied to the material by the microwave heater at
any or a
combination of these manufacturing points or stages, e.g., at or between
various
workstations along the manufacturing process. For example, microwave heat may
be applied to the substrates while being layered and laminated, after the heat-
expandable adhesives or coatings have been applied. Furthermore, microwave
heat
may be applied to individual product containers containing unexpanded
microspheres after they have been formed, e.g., during conveyance of the
products
to a workstation for packing the products into a shipping container.
[0024] Alternatively or in addition, microwave heat may be applied
through a
shipping container, e.g., a regular slotted carton into which a number of
products
have been packed. Further, microwave heat may be applied through a loaded
pallet
onto which a number of shipping containers are stacked. The heat-expandable
adhesives or coatings incorporated within or layered on the substrates of the
products may not be expanded (or may not be fully expanded) until application
of
the microwave heat at these later stages of the manufacturing process before
shipping.
[0025] A package container may be constructed of and/or insulated with
an
insulating material. The insulating material may be made of multilayer
laminated
substrate(s) or a coated substrate containing a heat-expandable adhesive or
coating.
The heat-expandable adhesive or coating may be expanded either before or after
formation of the package container from the multilayer substrate(s) by
application of
microwave heat. Other sources of heat or thermal energy such as hot air or
infrared
(IR) may also be applied in addition to the microwave heat.
[0026] The heat-expandable adhesive or coating may be applied onto the
container or within a container material or between container layers, or may
be
applied to an outer wall of a container, or to a combination of these. The
insulating
material containing the heat-expandable adhesive or coating may be expanded
before reaching an end user, such as when the container and/or a container
sleeve are
manufactured, and/or the insulating material may be expanded only at end use
and
only in response to, for example, some level of temperature of a hot beverage
or
food served within the container. The expanded insulating material may be used
to
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aid with insulating capabilities of the container and/or the container sleeve,
and/or to
add rigidity to the container and/or the container sleeve, and could help
reduce the
thickness of the material components of the container and/or the container
sleeve.
[0027] The sheet material used to make the package, container, and/or
container
5 sleeve may be manufactured on a conveyor-type machine system, in an
automated
assembly-line process, one example of which will be discussed in more detail
later.
The heat-expandable adhesive or coating may be applied by many conventional
application methods, such as non-contact like spray, and/or contact-like rod,
roll,
nozzle or slot extrusion, pad and brush coating methods or otherwise applied
onto
sheet material, for example, but not limited to, onto a corrugated medium
before a
liner is laminated onto it. The heat-expandable adhesive or coating may thus
be
located between two layers of some sort of sheet material before being
expanded
during the manufacturing process. When the insulating material is a coating,
the
insulating material may be applied to a monolayer (or single) sheet or to an
outside
surface of or within a multilayered sheet before expansion by heat. Other
embodiments are likewise possible, as discussed later, such as applying
microwave
heat after the formation of a multilayer substrate, or after the formation of
a product,
or before shipment of the containers from a warehouse to expand the expandable
adhesive or coating at some other point during or after the manufacturing
process.
[0028] In some embodiments, the heat-expandable adhesives/coatings are
heated
during a conveyor-type machine assembly process so the expansion occurs when
the
containers are manufactured. With conventional machine systems, the common
source of heat has been by a hot air and/or infrared (IR). Conventional
heating
methods, such as a hot air oven and/or an infrared heater installed in-line on
a
machine system alone are sometimes not effective to adequately activate heat-
expandable microencapsulated particles¨like microspheres or microtubes that
are
added to the heat-expandable adhesive(s) or coatings¨at production speed,
typically
150 feet per minute (fpm) to 600 fpm. This is due, in part, to the space and
heat
power limitations and the heating mechanism of these methods primarily based
on
conduction, convection, and radiation with heat transfer from outside to
inside of the
material being heated. With these conventional sources of heating,
accordingly,
technical issues are exhibited in the mode of thermal energy transfer, which
leads to
inefficient and constrained expansion of the heat-expandable microparticles.
For
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example, the outer part of the coating may be dried and solidify first,
significantly
constraining the expansion of the expandable microparticles.
[0029] It is proposed in the present disclosure to apply microwave
energy from
an industrial microwave heater adapted to apply microwave energy over and
through
the substrate material or packaging product containing the heat-expandable
adhesives or coating passing through it during the process. Accordingly, the
microwaves from the microwave heater can penetrate into and energize the
expandable adhesive or coating inside the substrate, causing them to heat up
more
uniformly, volumetrically and quickly than they would from the conductive,
convectional or surface radiant heat. This is due to the volumetric microwave
heating of the heat-expandable adhesives/coatings in a relatively short time.
For
example, heat-expandable microspheres mixed into the adhesives/coatings may
expand rapidly when the mixture in which the microspheres are located heats up
quickly from exposure to the powerful microwave energy.
[0030] The heat-expandable adhesive or coating may contain expandable
microencapsulated microparticles, like microspheres or microtubes from
multiple
different sources. Non-limiting examples include commercial products like
Dualite,
MicroPearl, and Expancel discussed earlier, and thermally expandable
microtubes
that may be used in formulating expandable materials.
[0031] The heat-expandable adhesives/coatings may include starch-based
glues,
may be synthetic or natural material-based, such as polyacrylates, polyvinyl
acetates, polyvinyl alcohol, starch, polylactic acid, and other material, and
may be
applied to many different substrate materials, such as paper, paperboard,
corrugated
board, plastic films, metalized films, textile, woven or nonwoven materials
and other
materials from which to make laminates or coated substrates. The heat-
expandable
adhesives or coatings may also facilitate material reduction, reducing adverse
environmental impact of packaging by reducing material while maintaining bulk
and
thermal insulative performance in packaging products. These laminated or
coated
substrates in turn can be converted into many useful food and non-food
packaging
products, for example, but not limited to, folding carton containers, hot and
cold
cups, boxes, paper clamshells, fluted sleeves, microfluted clamshells, E-
fluted box,
bag, and bag-in-boxes and other packaging products (referred to generally as
containers). The multilayer materials with expanded material provide more
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flexibility for someone to expand the choices for caliber and basis weight of
different substrates than what are commonly available and supplied by existing
material suppliers.
[0032] These heat-expandable adhesives/coatings can be applied in
conventional
corrugating laminator, printing press, coater, coating applicator, or other
application
methods, and expanded with the assistance of an industrial microwave heater to
boost efficiency and speed. The heat-expandable coatings can be applied onto
paper
substrates in full coverage or in pattern of any practical design, and
subsequently
expanded by the microwave heater to create a cellular or foamed structure in
the
coating layer with different end-use benefits, some of which will be explained
below.
[0033] Figure 1 illustrates a container 100, such as a cup, with an
inner wall
102and an outer wall 104.A blank for the outer wall 104 may be in the form of
a
container sleeve or a sidewall wrap for the body of the container 100. The
inner
wall 102 could be formed from a laminated board with expandable insulating
material on the outer surface thereof The insulating material could also be
positioned between the inner wall 102 and the outer wall 104. The outer wall
104
may not be needed when the inner wall 102 coated with the insulating material
includes adequate bulk and insulation.
[0034] The container 100 is not limited to a cup and may be any other
container,
including but not limited to, a bulk coffee container, a soup tub, press-
formed
containers, plate, sleeve (e.g., single face corrugated, double face
corrugated, non-
corrugated, cardboard, etc.), folding cartons, trays, bowls, clamshells, bag,
and
others with or without covers or sleeves. The container 100 may be a
cylindrical
cup or a container having other geometrical configurations, including conical,
rectangular, square, oval, and the like.
[0035] The outer wal1104blank is not limited to a corrugated die cut
blank, and
may be constructed of any kind of paperboard, paper, foil, film, fabric, foam,
plastic,
and the like. The outer wall 104 may be made of any nominal paper stock,
including
but not limited to, natural single-face, white-topped single face, coated
bleached top
single-face, corrugate, fluted corrugate, paper, paperboard, virgin paper,
recycled
paper, coated paper, coated paperboard or any combination of these materials.
The
outer wall 104 may be removable from the container 100 or the outer wall 104
may
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be adhered to the container 100. The outer wall 104 may be adhered, for
example,
by laminating the outer wall 104 blank onto the container, using a hot
adhesive, cold
glue and/or any other adhesive or sealing mechanism. Alternatively or in
addition,
the outer wall 104 blank may be adhered with an insulating material. If the
outer
wall 104 is attached to the cup during manufacture, such attachment may
increase
efficiency by eliminating the need to use an insulating sleeve by the end-
user.
Further, the attachment may decrease the amount of storage space required by
an
end-user, e.g., storing one item such as a double or multi-wall container as
opposed
to a container and a separate insulating sleeve.
[0036] Figure 1 is not necessarily drawn to scale. For example, the outer
wall
104 may cover a larger or smaller portion of the surface of the container 100
than
illustrated. For example, the outer wall 104 may provide full body coverage.
Increasing the surface area of the outer wall 104 may provide a larger
insulated area
as well as a larger print surface. Although the drawing illustrates the outer
wall 104
on a cup, the outer wall 104 may be added to any other containers, such as but
not
limited to, a bulk beverage container, press-formed container, and soup tub.
The
outer wall 104 may be added to a container as a wrap (Figures 2 and 3).
[0037] Figure 2 is a side cutaway view of a container 100, which may
be a
double wall cup with an inner wall 102 and an outer wall 104 or a single wall
cup
with a laminated board (including the inner wall 102 and the outer wall 104)
and an
expandable insulating material 216 between two material layers such as papers.
A
space 200 between the inner wall 102 and the outer wall 104 may be filled
partially
or wholly with the expandable insulating material, which may at least
partially fill
up after expansion of the insulating material from the application of heat
such as
from a microwave heater. The container 100 may be adapted to hold a liquid
206,
whether hot or cold, as well as solid materials such as food. For cold
beverage or
food, the enhanced insulation of the container walls will help not only keep
the
beverage or food cold longer, but also reduce or eliminate moisture
condensation on
the outside of the container. The outer wall 104 can be joined with the inner
wall
102 at the top and bottom to provide an enclosed gap in between.
[0038] The insulating material 216 may expand when the unexpanded heat-
expandable microspheres (or other forming agents) added in it are activated by
heat
after the container 100 is formed. Alternatively or in addition, the
insulating
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material 216 may be pre-expanded, for example, by the inclusion of pre-
expanded
microspheres, air or inert gas, in situ air voids in the insulating material
216. The
insulating material 216 may be activated by, for example, microwave or through
other heating methods. The insulating material 216 may include, but not be
limited
to, an aqueous coating containing heat-expandable microspheres, adhesives,
starch-
based adhesives, natural polymer adhesives, inert gas foamed hot melt,
synthetic
material, foam coatings, or any combination of these or other materials. In
one
example, the insulating material 216 with heat-expandable microencapsulated
microspheres may include a starch composition with a few, such as one to ten
percent microspheres mixed into the insulating material 216. The insulating
material 216may be biodegradable, compostable, and/or recyclable.
[0039] The insulating material 216may be expandable when wet or semi-
dry, or
dry depending on different formulations. The insulating material 216 may
include
any synthetic or natural binder material including aqueous-based materials,
high
solids, or 100% solid materials. The amount of solid content is typically 20%
to
80% of the material, and more preferably 30% to 60%. Other ingredients may be
added to the binder and/or insulating material 216, including but not limited
to,
pigments or dyes, mineral or organic fillers/extenders, surfactants for
dispersion,
thickeners or solvents to control viscosity for optimized application, foaming
agents,
additives like waxes or slip aids, moisturizer, salts for enhanced absorption
of
microwave energy, and the like. Alternatively, insulating material 216 may be
an
adhesive. The insulating material 216 may have several properties, including
but
not limited to: thermal insulation to keep container contents hot or cold;
absorption
of moisture condensation and/or liquid; may expand on contact with hot
material
(such as at temperatures of 150 F or more); and may remain inactive until
reaching
a predetermined activation temperature. For example, the insulating material
216
would remain inactive at about room temperature. The insulating material 216
may
be repulpable, recyclable, and/or biodegradable.
[0040] Figure 3 illustrates a cross section of an outer wall 104 in
Figure 2, such
as a sleeve or wrap assembled with the container 100. This figure is meant to
be
illustrative and not limiting. The cup may be replaced with any container, for
example, a press-formed tray, a soup tub, or a bulk beverage container. The
outer
wall 104 may have an inner face 306 and an outer face 304. An insulating
material
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216 may be applied to the inner face 306, the outer face 304, and/or to a
surface 302
between the inner face 306 and the outer face 304, such as to an inner wall of
the
sleeve. The inner face 306 and outer face 304 do not necessarily contain a
space
302 there between.
5 [0041] An insulating material 216, such as a heat-expandable material
with the
heat-expandable microspheres in unexpanded form may be applied to an inner
face
306 of the outer wall 104. The insulating material 216 may be applied as a
full coat,
film or in a pattern that does not materially alter the thickness of the outer
wall 104
before expansion. Applying the insulating material 216 to the inside of the
outer
10 wall 104 may also maintain the printability of the outer face of the
outer wall 104. If
the insulating material 216 on the outer wall 104 is assembled, for example,
with a
standard paper cup, it may maintain the slim profile of the cup. In the
alternative,
the heat-expandable material may be activated by the microwaves to expedite
expansion thereof during manufacturing, before being assembled as a wrap. This
assures that the expandable adhesive/coating is expanded during manufacturing
and
provides for additional stiffness and strength after manufacturing and before
use.
[0042] Figure4 is a view of an exemplary machine system 400 for
manufacturing packaging substrate material that can be used later for making
containers such as the container 100 discussed above. For example, but not
limited
to, the machine system 400 may be a conveyor-type machine system with a number
of stages, such as the Asitrademicroflute lamination machine made by Asitrade
AG
of Grenchen, Switzerland, cited as merely one example. Other types of printer,
coater and laminator can be used to make similar monolayer and multilayer
substrate
materials. Figure 4 provides three parallel views of a process: a view of the
machinery, A, a view of a manner in which the sheet material may travel
through the
machine, B, and across-section view of the resulting manufactured product, C.
The
machine system 400 may extend longitudinally over a considerable length and
may
include a number of workstations along its length. The sheet materials
assembled
into the packaging material or substrate travel from right to left along the
machine as
displayed in Figure 4.
[0043] The machine system 400 may use a first sheet material 402 which
may
be provided in bulk as a roll or web. The first sheet material 402 may be fed
into the
machine system 400 and through the various steps of the process by a wheel-
based,
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belt-based, or other conveyance system. Figure 4 illustrates the use of a
wheel-
based system; for example, a conveyor belt (1213 in Figures 12-13) may be
moved
along by wheels 406 and a series of belts. Alternatively or additionally, as
shown in
Figure 4, the machine system 400 may use sheet material, which may be pre-
printed.
Different machine systems may use die-cut blanks of the particular packaging,
for
example, blanks of cups, containers, plates, clam shells, trays, bags or
beverage
container holders, among others, in which case the sheet material 402 can be
blanks.
[0044] The first sheet material 402 may be composed of a generally
flat material
having some rigidity and being capable of being bent or scored to facilitate
bending
along determined lines. For example, the sheet material 402 may be single-face
liner paper, for example but not limited to Kraft paper, clay-coated news
board,
white-top liner, containerboards, solid bleached sulfate (SBS) boards or other
materials. The material may be treated, such as to provide increased water or
fluid
resistance and may have printing on selected portions of the material.
Alternatively
or additionally, the sheet material 402 may be composed of paper, paperboard,
recycled paper, recycled paperboard, corrugated cardboard, chipboard, plywood,
metalized paper, plastic, polymer, fibers, composite, mixtures or combinations
of the
foregoing, or the like. The first sheet material 402 may be made of recyclable
materials or may be compostable, biodegradable, or a combination of these.
[0045] The first sheet material 402 may be conveyed by a roller 408 to a
first
workstation 420. The first workstation 420 may be a corrugating or coating or
printing station. The first workstation 420 may also include a corrugating
roll. The
corrugating roll may shape the first sheet material 402, or other medium
paper, into
a series of waves or flutes. In the alternative, a monolayer or single sheet
substrate
may be passed in directly, without corrugation, as the first sheet material
402 or
paper medium.
[0046] The first workstation 420 may also include an applicator, which
may
apply a securing material to a side, i.e. to the flute top, of the first sheet
material 402
or to the side of other medium paper. For example, the applicator may have a
trough
containing a securing material, such as an adhesive, and coating roll
applicator
possibly with a metering tool, like rod or roll. The trough may be stationed
near the
corrugating roll such that the adhesive is applied to the tips of the waves or
flutes
generated by the corrugating roll. Additionally or alternatively, the securing
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material may be applied by spraying, brushing, nozzle extrusion or otherwise.
For
example, an applicator may apply the securing material by spraying it onto a
side of
the first sheeting (or other medium paper) material 402. The spray from the
applicator may be constant or intermittent and may create broken lines,
stripes, dots,
or ellipses of securing material. Designs and patterns may be applied by
moving the
applicator or by moving the first sheet material 402 relative to the sprayer.
[0047] The securing material may be, for example, an adhesive, a
thermal
insulating material 216, or other materials or coatings, for example, those
with
securing or bonding properties. Various expandable insulating materials 216
were
previously discussed in detail. Furthermore, the securing material may be a
hot melt
or a non-hot melt adhesive or a cold set adhesive, for example a hot-melt
adhesive,
starch-based adhesive, natural polymer adhesive, cellulose-based adhesive,
glue, hot
melt glues, polymeric binders, synthetics, foams, and the like.
[0048] The securing material may be delivered to the applicator from a
line 422,
which may originate at a conditioning and preparation station 432. The
microspheres or other expandable insulation material may be premixed with
starch,
a binder, or other additive material in the conditioning and preparation
station 432
before delivery to the applicator of the first workstation 420.
[0049] In some embodiments, the applicator may apply a pattern of a
heat-
expandable coating to the first sheet material or other paper medium, referred
to
herein as a monolayer sheet, which is then heated by a microwave heater to
cause
the heat-expandable coating to expand. This coated and patterned monolayer
sheet
may then be sent to be processed into a final product having the patterned
coating.
[0050] In still other embodiments, the first sheet material 402 may
also be
incorporated with a second sheet 404, for example, by pressing the second
sheet
material 404 to the first sheet material 402. The second sheet material 404
may be
secured to the first sheet material 402 by the securing material resulting in
a two-
layer sheet material 426, such as single-face fluted sheeting as shown in
Figure4, C.
Alternatively or additionally, the laminated material 426 may be flat two
layer
laminate of different substrate material discussed earlier.
[0051] The two-layer sheet material 426 may then go past or through an
industrial microwave heater 427, which may be built around the conveyor belt
after
the first workstation 420 to apply microwaves to the two-layer sheeting
(Figure 12).
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Moisture preferably remains within the heat-expandable insulating material 216
from the mixture prepared in the conditioning and preparation station 432.
This
moisture is susceptible to absorption of microwave power emanating from the
microwave heater 427, and thus heats up rapidly, causing to expand the
insulating
material 216 of the adhesive/coating applied by the applicator under the
appropriate
processing conditions, e.g., temperature, pressure and time.
[0052] The microwave heater 427 is preferably a planar type operated
at or near
about 915 MHz or about 2.45 GHz, or at some other acceptable frequency. The
microwave heater 427 may also be a tubular or other type of microwave heater
that
includes microwave applicators. These types of industrial microwave heaters
may
be used to dry water-containing mixtures or products, which contain polar
molecules
that absorb the electromagnetic energy in the microwave field, resulting in
heating
and drying the water, and sometimes in cooking the products. If planar, the
microwave heater 427 may include a narrow, open slot in between two panels of
the
microwave guides or channels for a paper web or other substrate to go through,
as
seen in Figures 12-13. If the microwave heater is tubular, product with
tubular or
round cross section can be transported through microwave applicators of the
heater
in a desirable configuration. The microwave heater 427 may not only dry the
paper
web or substrate, but activate and expand the expandable materials pre-applied
between or onto the paper layers.
[0053] The microwave heater may be designed differently or configured
to heat
the heat-expandable coatings and adhesives in substrate material or in
products at
different points during a manufacturing process, as illustrated and discussed
with
reference to Figure 11.
[0054] The temperatures at which the microwave heater 427 may heat the
substrate or product containing the heat-expandable materials such as
microspheres may range between 100 and 500 degrees Fahrenheit. The
temperature may vary greatly depending on the type of microspheres used and
the thickness of the material substrate and binder being heated. For example,
some commonly used microspheres are heated to temperatures ranging between
200 and 350 degrees Fahrenheit.
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[0055] The two-layer material sheet 426 may exit the machine system
400 and
go on to further processing such as die cutting, printing, conditioning,
folding, and
the like, which results in a final product. Alternatively, the two-layer sheet
material
426 may be further processed by the machine system 400 as described below.
Note
that the microwave heater 427 may be alternatively located along stations of
further
processing down the machine system 400. For example, an expandable adhesive or
coating may be applied at a later stage in the process, after which, at some
point, the
microwave heater 427 may be positioned to expand the adhesive/coating, as
discussed later. The location of the microwave heater 427 is therefore not
critical,
but some locations may be better for ease-of-attachment to the machine system
400
parts or may be better-applied at further steps of the manufacturing and
product
preparation processes.
[0056] The two-layer material sheet 426 may be conveyed to a second
workstation430. The second workstation 430 may include an applicator, which
may
apply a securing material to a side of the two-layer sheeting 426. For
example, the
applicator may apply a securing material to the second sheet material 404 side
of the
two-layer sheeting 426, which may be the liner side of the two-layer sheeting
426.
Alternatively or additionally, the applicator may apply a securing material to
the
first sheet material 402 side of the two-layer sheeting 426. The securing
material
may be or include an expandable adhesive or insulation coating. For example,
the
securing material may be an adhesive, for example a hot-melt adhesive starch-
based
adhesive, natural polymer adhesive, cellulose-based adhesive, glue, hot melt
glues,
cold set glues, binder, synthetics, polymeric binder, foams, and the like.
[0057] The securing material may be applied by spraying, brushing, or
otherwise. For example, the applicator may have a trough containing a securing
material and a metering tool. The trough may be stationed near the roll, which
feeds
the paper into the second workstation430 such that the securing material is
applied
to the tips of the waves or flutes generated by the corrugating roll. As a
second
example, an applicator may apply the securing material by spraying it onto a
side of
the first sheeting material 402, the second sheeting material 404, or both.
The spray
from the applicator may be constant or intermittent and may create broken
lines,
stripes, dots, or ellipses of securing material. Designs and patterns may be
applied
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by moving the applicator or by moving the first sheet material 402 relative to
the
sprayer.
[0058] The two-layer sheeting material 426 may be incorporated with a
third
sheet material 434, which may be a second liner, for example, by pressing the
third
5 sheet material 434 to the two-layer sheeting 426, creating a three-layer
sheet
material 434.
[0059] The three-layer sheet material 434 may be composed of a
generally flat
material having some rigidity and being capable of being bent or scored to
facilitate
bending along determined lines. For example, the three-layer sheet material
434
10 may be single-face liner paper, for example, but not limited to, Kraft
paper. The
material may be treated, such as to provide increased water or fluid
resistance and
may have printing on selected portions of the material. Alternatively or
additionally,
the third sheet material 434 may be composed of corrugated cardboard,
chipboard,
SBS, metalized paper, plastic, polymer, fibers, composite, mixtures or
combination
15 of the foregoing, or the like. The third sheet material 434 may be made
of
recyclable materials or may be compostable, biodegradable, or a combination of
these.
[0060] The second workstation 430 may be a printer, coater or
laminator. The
layers of the multilayered sheeting, such as the three-layer sheet material
434, may
improve the structural integrity and appearance of the resulting packaging
material.
The microwave heater 427 may alternatively be located at or near the second
workstation 430 to radiate with microwave energy the multilayered sheeting
passing
through the second workstation 430, during lamination, for example. The
microwave heater 427 may then rapidly heat, and thus expand, the adhesive or
coating¨that contains heat-expandable components such as microspheres¨applied
to the multilayered sheet as the securing material. The multilayered sheet
material
leaving the second workstation 430 may be further conditioned, cut or die-cut,
and
stacked for shipping, as will be discussed in more detail with reference to
Figure 11.
The multilayered sheet material may then be formed into the container 100.
[0061] Several lab feasibility tests have been performed using a common
office
microwave oven and a pilot planar, industrial microwave heater. E-flute single-
face
corrugate board and F-flute single-wall corrugated board were used as
substrates in
these tests. The results from these tests confirmed the feasibility of
activating and
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expanding the heat-expandable adhesive and coatings sandwiched between medium
and liner. The tests also showed an enhancement in drying and reducing steam
energy consumption. The tests also revealed that it is beneficial to design a
suitable
microwave energy field inside the microwave applicator to achieve optimal
expansion efficiency of the heat expandable adhesives and coatings, and
consequently increase line speed.
[0062] As one of the examples of the pre-activation method described
earlier,
Figure 5 is a side view of a vacuum conveyor 500 through which blanks 503 may
be
coated with heat-expandable material in any desirable pattern. The vacuum
conveyor 500 may be used independently or integrated into portions of an
automated
manufacturing system. The vacuum conveyor 500 may include a vacuum motor 510
that spins in the direction of desired travel of a conveyor belt 513, which
direction is
shown with a solid black arrow in Figure 5.
[0063] A plain or printed blank 503 that may be a mono or multi-layer
sheet
material, for example, but not limited to sheet material made from the machine
system 400 discussed above, may be processed through the vacuum conveyor 500.
In one example, the blank 503 is for use in a cup or in a double wall cup. A
glue
gun (or coating or printing station) 505, or other applicator 505, may apply
wet,
heat-expandable material 216 containing microencapsulated particles 506. A
microwave heater 427 or other source of heat energy supplies the energy to
activate
and expand the particles 506, causing the particles to expand into expanded
particles
508. The expanded particles 508 may form a pattern on the blank 503 of a
certain
desirable height. The height of the expanded particles may vary to some
degree.
[0064] The vacuum motor 510 of Figure 5 may be used to help hold the
blank
503 flat to allow uniform application of a proper amount of heat-expandable
coating
in a design pattern. In order to accomplish the proper delivery of the wet
particles
506, a controller that drives the vacuum motor 510 may tightly control the
RPMs of
the vacuum motor. Alternatively or additionally, the glue gun or coating
station 505
may be controlled in turning on and off, such as to intermittently lay down
the
proper amount of heat expandable material containing particles 506 in a design
pattern on each respective blank.
[0065] A tamper or sizing device 509 such as a wheel, block or nip
rolls may be
used to tamper down the expanded particles 508 to a relatively uniform
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17
predetermined height. A vision inspection or detection system 512 may then
detect
the quality of the expanded particles 508, for quality control before further
processing, e.g., by a double wall cup or container-building machine.
[0066] Figure 6 is a modified mandrel 600 adapted with one or two
raised strips
605 having vacuum holes 601 in each raised strip 605 (where Figure 6 shows
only
one raised strip by way of example). The raised strip 605 may be adapted at a
height
of approximately (or substantially) the uniform height of expanded particles
508
shown in Figure 5. The height of the raised strip 605 is about the same as or
slightly
higher than the height of the expanded particles 508 to allow a smooth and
proper
wrap around of each blank 503 with expanded particles 508 onto the mandrel 600
to
form a proper-fitting cup wrap for a double wall cup.
[0067] Figure 7 is an example of an outer wall blank 703 having a
patterned
coating 715 of heat-expandable material 216 having a gap 723 through which one
of
the raised strips 605 of the mandrel 600 may be located. In this way, the
vacuum
holes 601 may still create a sufficient suction on the smooth part of the
inside of the
blank 703 with which to hold the blank 703, which is wrapped around the
mandrel
to be transported. After the blank 703 is formed into an outer wrap of a cup,
a single
wall cup is placed inside the formed wrap in an automated process to make a
double
wall cup.
[0068] Figure 8 is a perspective view of a vacuum conveyor 800 using the
mandrel 600 such as that described with reference to Figure 6 to transport a
blank
having heat-expanded particles adhered to an inner side of the blank. The
vacuum
conveyor 800 may receive the blanks 503 from the vacuum conveyor 500 of Figure
5. The mandrel 600 may position one of its raised strips 605 within the gap
723 in
the heat-expanded pattern 715 of heat-expanded particles of the blank 503 and
the
other raised strip 605 underneath a seam area of the wrap of the blank 503,
e.g.,
where edges of the blank meet together to form the wrap. The vacuum holes 601
of
the raised strips help holding the wrap around the mandrel 600, making it
possible to
remove the blank 503 from the vacuum conveyor 800 and transport the blank 503
through the cup outer wrap forming step.
[0069] In the steps taken in Figures 5-8, a machine assembly is made
operable to
build a double wall cup in a manner in which the heat-expandable material 216
on
the substrate (blank 503) is first expanded before construction of the
container (the
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double wall cup), which was previously referred to as the pre-activation
method. As
will now be explained, in a post-activation method, a double wall cup may also
be
constructed by first constructing the cup in a machine assembly process, and
then
later expanding the heat-expandable microspheres existing within the heat
expandable material 216, to construct the insulating double wall cup.
[0070] As one non-limiting example of the many post-activation
methods,
Figures9 and 10 show a perspective view of a cup-building machine 900. The cup-
building machine 900 may include a set of glue guns 505, a pulley 908, a rod
910
and a belt 912. The machine 900 may also include a wheel 1001 operatively
attached to the rod 910 and including multiple spokes 1010. The wheel 1001 may
rotate in a direction tangential to the spoke 1010 while the cup on the cup
mandrel
600 may spin about an axis parallel with the spokes 1010 when engaged by the
rod
910. A mandrel 600 may be attached to the end of each spoke 1010. In the
depicted
embodiment, an inner cup 1020 of a double wall cup is prepared for adhesion to
an
outer wrap 1022 of the double wall cup (Figure 10).
[0071] As the belt 912 is pulled, the pulley 908 is turned in the
direction of the
narrow arrow, causing the rod 910 to also be turned, which in turn rotates the
inner
cup 1020 on mandrel 600. As the inner cup 1020 rotates, the glue guns 505
spray
the heat-expandable material 216 onto the outer wall of the inner cup 1020.
The
material application guns or nozzles are offset to enable multiple and
separate lines
of adhesives 216 to be applied on the outside of the inner cup 1020 with
predetermined spacing between the lines. The revolutions per minute (RPM's) of
the speed at which the rod 910 turns may include a tight tolerance, e.g., the
timing
may be such so that the coating from the guns 505 is properly spaced and
uniformly
spread: not too thick, not too thin. The wheel 1001 may then be rotated to
repeat on
the inner cup 1020 of the next spoke, e.g., rotating clockwise (in direction
of thick
arrow). Each coated inner cup 1020 may then be inserted into the next outer
wrap,
thus forming a double wall cup.
[0072] The double walled cup that is formed may then be transported,
stacked,
bagged and placed in cartons that will be shipped on pallets. As will be
explained
with reference to Figure 11, the microwave or other heat may be applied at the
various stations after the cup has been formed to post-activate the heat
expandable
material 216, in addition to before the cup has been formed.
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[0073] Figure 11 is a flow diagram 1100 of multiple workstations of
the
packaging product container manufacturing process at or between which
microwave
heat may be applied to expand heat-expandable microspheres (or other heat-
expandable microparticle material) incorporated as a part of substrate layers
of
packaging substrates and/or containers. The manufacturing process includes the
conveyance of the packaging substrates or containers between the workstations.
That the workstations are numbered sequentially does not mean that an order is
required, except where stated. Microwave heat may be applied to the substrate
or
containers at more than one workstation during the manufacturer assembly
process,
such that heat-expandable materials may be expanded during more than one
manufacturing stage to achieve the desired final expansion of the heat-
expandable
materials.
[0074] In addition to the first workstation 1120, the machine system
400 may
include a printing workstation 1125 configured for printing the substrate used
to
make containers that will be ultimately assembled for shipping. The printing
ink
may include heat-expandable microencapsulated microparticles. A microwave
heater 427 may be used during or after printing to heat up the sheet material
and the
securing material to expand, at least to some extent, the microspheres or
other heat-
expandable compounds within the printing material.
[0075] As discussed with reference to Figure 4, the second workstation 430
may
be configured to apply a coating in any pattern or lamination to the packaging
substrate material that has already been formed. The coating or laminating
process
may include application of additional layers of sheeting material or
coating/laminating the multi-layered substrate, such as to improve the
structural
integrity and appearance of the resulting packaging material. A microwave
heater
427 may then be used at some point thereafter to heat up the sheet material
and the
coatings applied during lamination to expand, at least to some extent, the
microspheres or other heat-expandable compounds within the coating and/or
securing material.
[0076] Adie cutting station 1140 may be configured to perform die cutting,
either rotary die cutting, or platen die cutting or both, the result of which
may
include blanks 1143 that may be formed into a finished product. The blanks may
include, for example, blanks 1143 of cups, containers, plates, clamshells,
trays, bags
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or beverage container holders, among others. A microwave heater 427 may then
be
used to heat up the blanks to expand, at least to some extent, the
microspheres or
other heat-expandable compounds within any coating, lamination or securing
materials of the blanks 1143, when having not yet been expanded.
5 [0077] A forming workstation 1150 may be configured to form finished
products 1153 from the blanks 1143.A microwave heater 427 may then be used to
heat up the finished products 1153 to expand, at least to some extent, the
microspheres or other heat-expandable compounds within any coating, lamination
or
securing materials of the finished products 1153, when having not yet been
10 expanded.
[0078] A cartoning workstation 1160 may be configured to package the
finished
products 1153 into a shipping carton such as a regular slotted carton. The
output
from the cartooning workstation 1160 includes stacked cartons 1163 packed full
of
the finished products 1153. A microwave heater 1127 may be used to heat
through
15 the shipping cartons 1163¨during the cartoning process or after they are
stacked¨
to expand, at least to some extent, the microspheres or other heat-expandable
compounds within any coating, lamination or securing materials of the finished
products 1153 packed in the shipping carton 1163, when having not yet been
expanded.
20 [0079] Where the containers are cups or container, these may be
conveyed
through a tube that is part of the forming workstation 1150. A microwave
heater
427 may be oriented around a portion of the tube through which the cups or
containers travel to heat up the heat-expandable materials, when having not
yet been
expanded, in route as the cups or containers are sent through the tube to be
packed in
cartons and palletized.
[0080] A palletizing workstation 1170 may be configured to receive the
stacked
cartons of product containers onto pallets. A microwave heater 427 may be used
to
heat up a pallet of stacked cartons or containers to expand, at least to some
extent,
the microspheres or other heat-expandable compounds within individual product
packed in the cartons, but for an entire pallet at a time, when having not yet
been
expanded. The pallets may then be loaded onto trucks for shipping at a
shipping
workstation1290.
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[0081] Figures 12 through 15 include various schematic views of the
microwave
applicator guide(s) that may be used for the microwave heater 427, which may
be
installed around one or more conveyor belts 1213 that convey the paperboard,
sheet
material, or other substrate through the machine system 400. The microwave
heater
427 of may be a planar type having a slot 1405through which the web, sheet, or
blank material passes. Figure 14 shows a cross-machine side view while Figure
15
shows a front or machine-direction view of the microwave heater 427. The
microwave heater 427 may include a number of micro-waveguide channels that are
connected together to provide increased surface area with which to apply
microwave
energy to the sheet material. The dimensions displayed in Figures12 through 15
of
the microwave heater 427 are but exemplary and not meant to be limiting. When
tubular microwave applicator is used for 427, the cross section of the tubular
applicator is generally circular, and there is an opening through the
applicator to
allow product to pass through.
[0082] Figure 16 is a flow chart of an exemplary method for manufacturing a
multilayer sheet material in a process that includes microwave heating of the
multilayer sheet material to expedite expansion of a heat-expandable adhesive
or
coating. The dashed lines in Figurel7indicate optional routes that may bypass
one
or more steps of the method. At block 1600, a first sheet material may be
loaded
into the machine system 400 and may be corrugated. At block 1610, a securing
material may be applied to a side of the first sheet material. The securing
material
may be a heat-expandable adhesive or coating, which may include a starch and
microspheres or some other composition. At block 1620, a second sheet material
may be applied to the first sheet material. If this two-layer sheet material
has a
securing material that includes the heat-expandable coating, the two-layer
sheet
material may be heated at block 1630 with microwave energy to expand the heat-
expandable adhesive/coating. At block 1640, the two-layer sheet material may
be
conveyed to processing into a final product, such as by printing, die cutting,
removing from blanks, and/or being assembled.
[0083] At block 1650, a second securing material may be applied to a side
of the
two-layer sheet material. The second securing material may be a heat-
expandable
adhesive or coating, which may include starch and microspheres and/or some
other
adequate composition. Following this step, the multilayer sheet material may
skip
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forward certain steps and get heated and/or laminated without first having a
third
sheet material applied. Otherwise, at block 1660, a third sheet material may
be
applied to an exposed side of the first or second sheet materials. At block
1670, if
the second securing material is a heat-expandable adhesive or coating, the
multilayer
sheet material may be heated with microwave energy to expand the heat-
expandable
adhesive or coating. At block 1680, the multilayer sheet material may be
laminated.
That is, if the first, second, and third sheet materials have been applied
together, then
the first, second and third sheet materials may be laminated together at block
1680.
At block 1640, the multilayer sheet material or substrate may then be
processed into
a final product, which may include printing, die cutting, being removed from
blanks,
and/or being assembled. In addition, or alternatively, microwaves may be
applied to
the multilayer sheet material or substrate at any of these various stages (or
workstations), including but not limited to: printing, coating and/or
laminating, die
cutting, forming, cartoning RSC and preparing pallets of cartons or containers
for
shipment.
[0084] For example, the resulting multilayer sheet material may be
further
processed such as by application¨and subsequent removal of¨packaging blanks
from the sheet material and assembly of the blanks into the final product
(block
1640). The final product of the process (which may be, e.g., a cup, container
holder,
containers sleeve, clamshell, tray, and the like) may be made of one or more
layers
of one or more of the aforementioned materials. Where multiple layers of
material
are used, they may be joined such as, but not limited to, being laminated,
glued, or
otherwise fastened together for increased strength.
[0085] As mentioned, use of the insulating material 216 may help to
reduce the
thickness of paper needed to make the container, sleeves, etc., while
maintaining
bulk of the laminated substrate and provide a more rigid feel to the consumer.
The
insulating material 216 may also improve insulation properties of the
container, and
to help keep the beverages or foods warm or cold longer, depending on the
application. The substrates may be made of natural fibers, synthetic or both,
such as
natural or bleached paper, natural or bleached paperboard or boxboard with or
without recycled fibers. In combination, the features and processes disclosed
herein
add significant flexibility and versatility to the conventional converting
processes
and broaden choices available to packaging converters to address any
limitation of
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substrate supply in the supply chain. For example, laminates of two thin liner
papers
may be used to make a bulkier paper with an expanded adhesive between the thin
papers with the same or better thermal insulation as a thicker paperboard. Hot
sandwich wraps could be made of such a material, which can be more flexible
than
paperboard. As an additional example, laminates may be manufactured of a low
gauge poly coated SBS board and a clay coated news board with the expandable
adhesives therebetween. As an additional example, drinking cups for hot or
cold
fluids may be manufactured to include a laminate of two different low gauge
boards
with the expandable adhesives therebetween. The expandable adhesives can be
activated during lamination, before or after the cup is formed. The expandable
adhesive can also be applied in pattern to achieve localized expansion and
therefore
localized rigidity and insulation improvement.
[0086] While various embodiments of the invention have been described,
it will
be apparent to those of ordinary skill in the art that many more embodiments,
variations and implementations are possible that are within the scope of the
invention. For example, steps of a method as displayed in the figures or
reflected in
the below claims do require a specific order of execution by the way they are
presented, unless specified. The disclosed steps are listed as exemplary such
that
additional or different steps may be executed or the steps may be executed in
a
different order.
