U.S. patent application number 10/885674 was filed with the patent office on 2004-12-02 for insulated beverage or food container.
This patent application is currently assigned to Appleton Papers, Inc.. Invention is credited to Debraal, John Charles, Lazar, John MacKay.
Application Number | 20040238989 10/885674 |
Document ID | / |
Family ID | 32849456 |
Filed Date | 2004-12-02 |
United States Patent
Application |
20040238989 |
Kind Code |
A1 |
Debraal, John Charles ; et
al. |
December 2, 2004 |
Insulated beverage or food container
Abstract
An insulating beverage or food container or sleeve is produced
with a foam layer disposed on an inner surface of a paper stock. A
polymer shrink film layer is arranged in a position along an inside
surface of the beverage container. The foam layer is sandwiched
between the polymer shrink film layer and the paper stock and
decreases the energy transfer between the beverage and the user's
hands allowing the user to hold onto the container for an extended
period of time without causing user discomfort or pain. The polymer
shrink film layer is produced from a shrink film polymer having a
percent shrink in the range of 30% or less, and more particularly a
percent shrink range of 5 to 10%.
Inventors: |
Debraal, John Charles;
(Appleton, WI) ; Lazar, John MacKay; (Custer,
WI) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Assignee: |
Appleton Papers, Inc.
|
Family ID: |
32849456 |
Appl. No.: |
10/885674 |
Filed: |
July 8, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10885674 |
Jul 8, 2004 |
|
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|
10167463 |
Jun 13, 2002 |
|
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60298386 |
Jun 18, 2001 |
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Current U.S.
Class: |
264/46.4 ;
264/230 |
Current CPC
Class: |
B29C 44/12 20130101;
B32B 27/32 20130101; B32B 2317/12 20130101; Y10T 428/1352 20150115;
B65D 81/3865 20130101; B31B 2120/402 20170801; B32B 2307/304
20130101; Y10T 428/1376 20150115; B29C 48/08 20190201; B32B 2323/04
20130101; Y10T 428/1303 20150115; B29L 2031/7132 20130101; B31B
2120/40 20170801; Y10T 428/1328 20150115; B29K 2105/04 20130101;
Y10S 220/902 20130101; B29L 2009/00 20130101; B32B 2439/02
20130101; B29C 48/00 20190201; B31B 2105/00 20170801; Y10S 220/903
20130101; B32B 27/10 20130101 |
Class at
Publication: |
264/046.4 ;
264/230 |
International
Class: |
B29C 044/06 |
Claims
What is claimed is:
1. A method of producing an insulated container, comprising the
steps of: providing a paper cupstock having a container wall for
surrounding an interior space, a bottom portion, and a paper stock
layer arranged along an exterior surface of said container wall;
mixing a blowing agent into a foamable polymer layer; forming a
foam layer along an inside surface of the interior space; adhering
a polymer shrink film layer to said foam layer; and heat treating
the container to shrink the polymer shrink film layer between a
percent shrink range of 30% or less.
2. The method of producing an insulated container according to
claim 1, further comprising the step of arranging an additional
polymer film layer in a position interposed between said foam layer
and said paper stock layer.
3. The method of producing an insulated container according to
claim 1, further comprising the step of applying a thermal
insulating coating in a position interposed between said foam layer
and said paper stock layer.
4. The method of producing an insulated container according to
claim 1, wherein said percent shrink range is between 5 to 10%.
5. The method of producing an insulated container according to
claim 1, wherein said foam layer is laminated, melted or extruded
foam formed from high density polyethylene, low density
polyethylene, linear low density polyethylene, or oriented
polypropylene, said heat treating step including a treating process
and a cooling process.
6. The method of producing an insulated container according to
claim 1, further comprising the step of forming the container for a
food or container beverage container and wherein the interior space
is a food or beverage containing space.
7. A method of producing an insulated food or beverage container or
sleeve, comprising the steps of: providing an insulated container
or sleeve having an interior space, said interior space including a
polymer shrink film layer and a foam layer along an interior
surface thereof; and heating the interior surface to shrink the
polymer shrink film layer; and removing wrinkles along the foam and
polymer shrink film layers during the heating step to thereby
prevent a wrinkling effect in the interior space.
8. The method of producing an insulated food or beverage container
according to claim 7, further comprising the step of applying a
polyethylene film layer in a position interposed between said foam
layer and said paper stock layer.
9. The method of producing an insulated food or beverage container
according to claim 7, wherein the heating step includes at least
one of heating a supply of air for transporting and stacking the
food or beverage container, heating a forming mandrel for the food
or beverage container, and transporting the food or beverage
container through a tunnel heater.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Divisional Application of Application
Ser. No. 10/167,463 filed on Jun. 13, 2002, the entire contents of
which are hereby incorporated by reference. The present inventors
also claim the benefit of U.S. Provisional Application Ser.
60/298,386, filed on Jun. 18, 2001, Attorney Docket Number
0011-0372P, "Insulated Beverage or Food Container;" the entire
contents of which are hereby incorporated by reference. The present
inventors also claim the benefit of U.S. Non-Provisional
Application Ser. No. 09/923,332, filed on Aug. 8, 2001, Attorney
Docket Number 0011-0377P, "Insulated Beverage or Food Container;"
the entire contents of which are hereby incorporated by
reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to an apparatus and method for
insulating containers and container stock material. In particular,
the present invention relates to an insulated, paper-based beverage
or food container or stock material having improved insulation
properties and a method of producing these insulated containers or
stock materials.
[0004] 2. Description of the Background Art
[0005] Current standard paper cup stock permits excessive heat
transfer through the wall of an insulated beverage container.
Accordingly, a user's hand becomes uncomfortably or sometimes even
painfully hot when excessive heat transfer is permitted through the
container wall. This may require the user to be inconvenienced by
having to release the container due to the excessive heat of the
container's contents. Thus, such containers have a low hold time.
An analogous but opposite situation can occur with very cold
beverages, where heat from a user's hand is transferred rapidly to
the contents of the container.
[0006] U.S. Pat. No. 4,435,344 to loka describes a method for
producing an insulating composite paper container having a body
member and a bottom member. The body member is formed of paper
coated or laminated with a thermoplastic synthetic resin film. A
surface of the body member is then heated to form a foamed
polyethylene heat-insulating layer on either or both of the inner
and outer surfaces of the container's body member. The
heat-insulated body member is then attached to the bottom
member.
[0007] U.S. Pat. Nos. 6,030,476 and 5,840,139 to Geddes et al.
describe a method for producing insulating beverage containers or
cups, stock material and containers made therefrom. A stock
material includes a base layer, an insulating layer formed on a
portion of the base layer, and a printed pattern/mineral oil
applied to the insulating layer. The insulating layer is formed
using a thermoplastic synthetic resin film. Also, U.S. Pat. No.
6,030,476 describes a polyethylene foam on the outside surface of
the paper cup.
[0008] European Patent Application EP 0940240 A2 describes a heat
insulating paper cup with targeted insulation in areas where
printed matter exists. The body member of the cup is coated on its
outside surface with a foamable synthetic resin and on its inside
surface with a synthetic resin laminate to prevent liquid
penetration. The bottom panel member is optionally coated on its
upper surface with a foamed or an unfoamed synthetic resin. Printed
matter is provided prior to foaming of the synthetic resin on the
outer surface of the cup with water-based ink. Further, the low
density polyethylene is foamed by vaporizing the water contained in
the paper stock.
[0009] European Patent Application EP 1060879 A2 describes a heat
insulating paper cup having a body member partially or fully coated
on its outside surface with a foamed low density polyethylene and
coated on its inside surface with an unfoamed modified low density
polyethylene.
[0010] However, the present inventors have determined that the
devices and methods of the background art suffer from the following
disadvantages. Other designs sacrifice the outside printability of
the cup to provide insulation or do not provide adequate insulation
properties.
[0011] The background art has not yet achieved insulated paper
stock that is capable of effectively impeding heat transfer between
the contents of the container and the exterior. In addition,
adequate thermal insulation is not achieved from the background art
in a manner that is cost effective.
SUMMARY OF THE INVENTION
[0012] The present invention overcomes the shortcomings associated
with conventional devices and methods, and achieves other
advantages not realized by conventional devices and methods.
[0013] It is an aspect of the present invention to provide an
insulated beverage container, sleeve or stock material that reduces
the energy transfer through a container wall, and offers increased
functionality and usefulness.
[0014] It is an aspect of the present invention to provide a
container, sleeve, or stock material having superior hold times and
pre-disposed to high quality printing and graphics.
[0015] The present invention is a recognition, in part, that the
ability to produce blank paper cups, sleeves or stock material that
can be printed/graphically enhanced is desirable. This invention
permits a superior insulating cup product to be made from
standardized manufacturing processes.
[0016] These and other aspects of the present invention are
accomplished by an insulated container stock material comprising a
paper stock layer; a foam layer disposed along an interior surface
of the paper stock layer; and a polymer shrink film layer having a
percent shrink of 30% or less.
[0017] These and other aspects of the present invention are also
accomplished by an insulated container comprising a container wall
having an exterior surface and an interior surface; a bottom
portion engaging the container wall along a lower side portion
thereof; a paper stock layer arranged along the exterior surface of
the container wall; a foam layer arranged along the interior
surface of the container wall; and a polymer shrink film layer
having a percent shrink of 30% or less.
[0018] These and other aspects of the present invention are also
accomplished by an insulated container comprising a container wall
having an exterior surface and an interior surface; a bottom
portion engaging the container wall along a lower side portion
thereof; a paper stock layer arranged along the exterior surface of
the container wall; a foam layer arranged along the interior
surface of the container wall; and a polymer shrink film layer, the
foam layer being sandwiched between the polymer shrink film and the
paper stock layer.
[0019] These and other aspects of the present invention are also
accomplished by an insulated food or beverage container sleeve
comprising a paper stock layer having an interior surface; a foam
layer disposed along the interior surface of the paper stock layer;
and a polymer shrink film layer having a percent shrink of 30% or
less, the foam layer being sandwiched between the paper stock layer
and the polymer shrink film layer. However, the shrink film layer
may not be necessary in all embodiments of the present invention,
e.g., a beverage container sleeve will not require a shrink film
layer.
[0020] These and other aspects of the present invention are also
accomplished by a method of producing an insulated container,
comprising the steps of providing a paper cupstock having a
container wall for surrounding an interior space, a bottom portion,
and a paper stock layer arranged along an exterior surface of the
container wall; mixing a blowing agent into a foamable polymer
layer; forming a foam layer along an inside surface of the interior
space; adhering a polymer shrink film layer to the foam layer; and
heat treating the container to shrink the polymer shrink film layer
between a percent shrink range of 30% or less.
[0021] These and other aspects of the present invention are also
accomplished by a method of producing an insulated food or beverage
container or sleeve, comprising the steps of providing an insulated
container or sleeve having an interior space, the interior space
including a polymer shrink film layer and a foam layer along an
interior surface thereof; and heating the interior surface to
shrink the polymer shrink film layer; and removing wrinkles along
the foam and polymer shrink film layers during the heating step
reducing or eliminating a wrinkling effect in the interior
space.
[0022] Further scope of the applicability of the present invention
will become apparent from the detailed description given
hereinafter. However, it should be understood that the detailed
description and specific examples, while indicating preferred
embodiments of the invention, are given by way of illustration
only, since various changes and modifications within the spirit and
scope of the invention will become apparent to those skilled in the
art from this detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] The present invention will become more fully understood from
the detailed description given hereinafter and the accompanying
drawings which are given by way of illustration only, and thus are
not limitative of the present invention, and wherein:
[0024] FIG. 1 is a side cross-sectional view of an insulated
beverage or food container according to the present invention;
[0025] FIG. 2 is a cross-sectional view of an insulated beverage
container wall or sleeve according to the present invention;
[0026] FIG. 3 is a cross-sectional view of an insulated beverage
container wall according to a first embodiment of the present
invention;
[0027] FIG. 4 is a cross-sectional view of an insulated beverage
container wall according to a second embodiment of the present
invention;
[0028] FIG. 5 is a cross-sectional view of an insulated beverage
container wall according to a third embodiment of the present
invention
[0029] FIG. 6 is a cross-sectional view of an insulated beverage
container wall according to a fourth embodiment of the present
invention;
[0030] FIG. 7 is a graphical view of experimental data representing
actual and comparative hold times for embodiments of the present
invention and commercial available products;
[0031] FIG. 8 is a cross sectional view of an insulating beverage
container sleeve according to the present invention;
[0032] FIG. 9 is a cross-sectional view of an insulated beverage
container wall or beverage container sleeve wall according to a
fifth embodiment of the present invention;
[0033] FIG. 10 is a plan view depicting an interior and exterior of
a beverage container or sleeve wall according to the present
invention; and
[0034] FIG. 11 is a plan view depicting an interior and exterior of
a beverage container or sleeve wall according to the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0035] The present invention is directed toward an insulated
beverage or food container, cup or sleeve; the container stock
material; and a method of producing insulated beverage or food
containers or stock materials that utilize a polyethylene foam
layer extruded or laminated to a surface of a food or beverage
paper stock. The present invention is described in greater detail
hereinafter with reference to the accompanying drawings.
[0036] FIGS. 2 through 6 are cross-sectional views of an insulated
beverage container wall 11 according to various embodiments of the
present invention. One of skill in the art will appreciate that an
insulated container 10 as shown in FIG. 1 can readily incorporate
any of the beverage container walls depicted in FIGS. 2 through
FIG. 6. While the following description is directed toward a cup,
the techniques of this invention can be applied to any number of
containers or surfaces, for instance a beverage container,
insulating beverage sleeve or stock material can be constructed
from any of the embodiments shown in the accompanying drawings.
[0037] FIG. 1 is a side cross-sectional view of an insulated
beverage container 10 according to the present invention. The
insulated beverage container includes a container wall 1 having an
upper side portion 7, a lower side portion 8 and a bottom portion
9. A beverage containing space 11 is formed between the container
wall's 1 upper side portion 7, lower side portion 8 and bottom
portion 9.
[0038] As aforementioned, current standard paper cup stock allows
excessive heat to transfer through the wall of the container. This
results in a user's hand becoming uncomfortably or sometimes even
painfully hot or cold when grasping a hot or cold container. A
quantitative measurement of the ability of a paper stock to
withstand heat transfer between the beverage containing space and
the outermost surface of the container is often referred to as hold
time. It will be appreciated that the present invention
significantly improves the hold time of paper-based stock beverage
containers over the related art.
[0039] The present invention utilizes a gas containing film adhered
or selectively adhered to the surface of a paper stock. The gas
containing film layer provides resistance to heat transfer through
the container wall 1. The present invention provides an insulating
container construction and a method of producing this construction
which reduces the energy transfer through the container wall,
providing increased functionality and usefulness.
[0040] FIG. 2 is a cross-sectional view of an insulated beverage
container wall or sleeve 1 according to a first embodiment of the
present invention. A beverage container wall or sleeve 1 includes a
paper stock 2, and an extruded or laminated foam layer 3. The paper
stock 2 provides structural rigidity and forms the desired shape of
the container 10 or a portion of a sleeve wall. The extruded or
laminated foam layer 3 is adhered to an inner surface (e.g., facing
the beverage containing space 11) of the paper stock 2 and performs
the function of a gas containing film layer. The foam layer 3 is
designed to provide thermal insulation properties to the
container.
[0041] The paper stock 2 is standard paper used for making beverage
cups and other food containers. The paper stock 2 may be chosen
with a thickness that provides optimized physical characteristics
for cup construction. Important physical characteristics include
fold strength, stiffness, tear and tensile strength.
[0042] A desired paper thickness is chosen such that the resultant
thickness of the finished cup wall 1 does not negatively impact
converting, handling or finished cup properties. A typical paper
stock 2 for beverage and food containers range from 10 to 40 mils
in a paper stock 2 thickness, and more particularly from 10 mils to
26 mils in thickness in a preferred embodiment for the present
invention. Where the present invention is applied to an insulating
beverage sleeve, the paper stock 2 may be chosen with a thickness
which provides the proper physical characteristics such as strength
for constructing a sleeve surrounding a beverage container 10 such
as that shown in FIG. 1.
[0043] Important physical characteristics include fold strength,
stiffness, tear and tensile strength. The paper thickness is chosen
such that the resultant thickness of the sleeve and cup wall does
not negatively impact handling, distribution or become cumbersome
to the end user. Additional criteria affecting paper stock
selection includes appearance and cost. A smooth, bleached-white
paper may be chosen to enhance the print quality and the appeal of
the cup, or a brown kraft stock may be chosen for economy.
Applicable paper suitable for sleeve stock ranges from 2 mils to 10
mils for the application to an insulating beverage sleeve.
[0044] The extruded or laminated foam layer 3 is applied to the
paper stock 2 as an extrusion or lamination. The purpose of the
extruded or laminated foam layer 3 is to provide thermal insulation
properties, and to contain liquids. The extruded or laminated foam
layer 3 can also be used as a barrier to moisture transmission and
further aids in seam sealing during container construction. In the
case of an insulating beverage sleeve, the foam layer 3 is a gas
containing layer that provides resistance to heat transfer through
the sleeve wall.
[0045] The extruded or laminated foam layer 3, although not limited
to, can be formed from any of the following exemplary materials:
high density polyethylene (HDPE), low density polyethylene (LDPE),
linear low density polyethylene (LLDPE), orientated polypropylene
(OPP), etc. HDPE and LDPE are desirable materials in a preferred
embodiment of the present invention. Although not necessary,
additional foam polymers may include and/or be formed from PEFSs,
LDPEs or HDPEs that are not tensioned or stretched during
manufacturing.
[0046] Additives may also be included to enhance various material
properties or to aid in the manufacturing process. These additives
include, but are not limited to, any of the following exemplary
additives: ethylene vinyl acetate (EVA), ethylene vinyl alcohol
(EVOH), and plasticizers.
[0047] The foam layer 3 is attached to the paper stock uniformly
during the manufacturing process. The gases trapped within the film
of the foam layer 3 impart a high level of thermal insulation to
the container wall. An important aspect of the gas containing foam
layer 3 is to provide resistance to energy transfer. The amount of
trapped gas is variable and depends upon a specified volume that
will render the exterior of the container comfortable to hold for
an average user. Therefore, the required amount of trapped air will
generally vary according to the intended use of the container.
[0048] For instance, a container used to serve coffee (normally
190.degree. F.) will need more resistance to energy flow than a
similar container used to serve a relatively cool cup of soup
(normally 165.degree. F.). An additional benefit to the insulating
layer is the ability of the container to keep the food or beverage
at its serving temperature for a longer period of time.
[0049] A foam layer 3 can be either laminated to or extruded onto
the paper stock 2. When the foam layer 3 is laminated to the paper
stock layer 2, a gas containing film such as CA-20 manufactured by
Sealed Air Corporation or another may be used. When the film is
extruded onto the paper stock 2 a blowing agent is mixed into the
polymer prior to extrusion. The incorporated blowing agent creates
gas pockets within the film during the extruding process. The
extrusion method offers the additional advantage of creating the
product in one operational step.
[0050] The insulating foam layer 3 is preferably between 2 and 30
lbs/3300 ft.sup.2, and more preferably between 5 and 15 lbs/3300
ft.sup.2. The density of the film is preferably between 1.0 and 3.0
lbs/ft.sup.3. The thickness of the insulating gas containing foam
layer 3 is preferably between 5 and 30 mils, and more preferably
between 10 and 20 mils. The foam layer 3 can be a gas containing
film layer formed from a continuous single layer or lamination of
films and foam.
[0051] Polymer Shrink Films
[0052] FIG. 3 is a cross sectional view of a container wall
according to a first embodiment of the present invention. A polymer
shrink film layer 4 is extruded, laminated, or coated to the foam
containing layer 3, e.g. in a position between the beverage
containing space 11 and the foam containing layer 3 in a container
10. The foam layer 3 is therefore interposed between the paper
stock 2 and the polymer shrink film layer 4. The polymer shrink
film layer 4 will hereinafter be referred to as a PE layer 4. The
PE layer 4 can be used as a barrier against moisture transmission
and aids in seam sealing during container construction.
[0053] In a preferred embodiment, the foam layer 3 is first formed
and then it is melt extruded, laminated or melt fused to the
surface of the paper stock 2. The residual moisture held within the
paper stock 2 which is characteristically relied upon in the
related art, is not relied upon as the mechanism for creating the
foam layer 3. The foam can also be extruded to the paper stock 2,
but in each instance the foaming is created by mixing a blowing
agent into the polymer prior to extrusion or foam creation. The
incorporated blowing agent creates gas pockets within the film
during the extruding process. The extruded method offers the
advantage of directly creating the product in one operational
step.
[0054] The foam layer 3 can also be treated in order to accept or
conform with various printing inks. The foam layer 3 can be treated
by various means well known in the industry such as, but not
limited to: corona treatment, flame treatment, ozone treatment,
coatings, etc.
[0055] FIG. 4 is a cross sectional view of a container wall
according to a second embodiment of the present invention. A PE
layer 4 is extruded, laminated, or coated in a position interposed
between the foam layer 3 and the paper stock 2. However, PE layer 4
can also be used as a barrier against moisture transmission and
aids in seam sealing during container construction. As seen in FIG.
5, the foam layer 3 can also be sandwiched between two PE layers 4,
e.g. an innermost PE layer is adhered directly to the paper stock
layer 2 in a third embodiment.
[0056] The PE layer(s) 4, although not limited to, can be formed
from any of the following exemplary materials: high density
polyethylene (HDPE), low density polyethylene (LDPE), linear low
density polyethylene (LLDPE), orientated polypropylene (OPP), etc.
HDPE and LDPE are desirable materials in a preferred embodiment of
the present invention. Some additional and applicable shrinkable
thermoplastics are PVC, PTFE, FEP, PVDF, PET, LDPE, LLDPE, HDPE and
polyolefin, that may be readily incorporated into the claimed
invention.
[0057] The PE layer(s) 4 can be manufactured to develop a property
called shape memory. When the PE layer(s) 4 are subject to axial
tension and stretching during manufacture or heated while under
tension and then allowed to cool, the PE layer(s) 4 develop shape
memory. Shape memory causes the PE layer(s) to shrink, e.g. the
polymer molecules relax to their original shape, when reheated. The
present inventors have determined that the shape memory of
particular PE layer(s) can be used advantageously in conjunction
with paper stock materials to produce polymer shrink film layers 4
that reduce and/or eliminate a wrinkling effect discussed in
greater detail hereinafter.
[0058] Additives may also be included to enhance various material
properties or to aid in the manufacturing process. These additives
include, but are not limited to, any of the following exemplary
additives: ethylene vinyl acetate (EVA), ethylene vinyl alcohol
(EVOH), and plasticizers.
[0059] FIG. 6 is a cross sectional view of a container wall
according to a fourth embodiment of the present invention. A PE
layer 4 has been applied to an outside surface or interior surface,
e.g. a surface opposite to the foam layer 3 with respect to the
paper stock 2. The PE layer 4 can be laminated, extruded or coated
onto the paper stock surface. The PE layer 4 also serves a barrier
to the beverage or food placed within the container, and can also
serve as a sealing mechanism. Alternatively, the PE layer 4 could
be applied as the innermost layer, e.g., closest to the beverage
containing space 11. Further, additional PE layers 4 and/or foam
layers 3 can be applied to either the inside or outside surfaces of
the container wall 1 as desired to add additional barriers and/or
thermal resistance to the liquid or heat sealed within (or excluded
from) the container. The PE layer 4 can be applied directly to the
paper stock 2 or indirectly over the foam 3.
[0060] A preferred coating material for additional coating layers
for the present invention is an expanding foam. This expanding foam
material is encapsulated isobutane in a polymeric shell. The
expanding foam capsules are added to the coating with a small,
e.g., unexpanded, diameter. Upon drying the foam and increasing the
heat to a certain temperature, the encapsulated isobutane changes
from a liquid to a gas and the polymeric shell expands with the
appropriate volumetric change.
[0061] The resulting expanded spheres or cavities have a very low
density and low thermal conductivity. Expanded foam also has the
advantage of creating a rough surface that will further reduce the
contact area between layers in the container wall and therefore
reduce heat transfer. A thin layer of the expanding foam coated
onto the paper stock exterior is especially useful for roughening
or for texturing to aid in gripping the container.
[0062] A preferred coating is a foamed coating. Foamed coating is a
coating that utilizes entrained air. The dispersed air in the
coating provides a low coating density and low thermal
conductivity. The foamed coating also accepts and is easily
processed to achieve surface modification. The foamed coating will
therefore allow a rough or perforated surface to be created through
the use of an embosser, press or other mechanical device.
[0063] Foam coating also has the ability to be used as a single
coating, or may also act as the insulating coating and a printing
coating simultaneously, depending on the application and desires of
the end user.
[0064] The selected coating materials for the insulating coating
are dispersed in an aqueous system with additional components added
as necessary to provide ease of processing and application.
Pigments such as silica, calcium carbonate, clay and synthetic
pigments may be also used.
[0065] Binders are included to adhere the coating to the paper
substrate. Typical binders may be selected from, but are not
limited to, polyvinyl alcohol, SBR latex, starch, polyacrylates and
other binders well known in the related art. Other additives may be
included in the coating to aid in dispersion, rheology and coating
handling. These additives include, but are not limited to,
defoamers, dispersants, wetting agents, conductive polymers,
styrene malefic anhydride, thickeners, etc.
[0066] An insulating coating can be applied that is between 2 and
30 lbs/3300 ft.sup.2, and more preferably between 5 and 15 lbs/3300
ft.sup.2. A preferred thickness of the insulating coating is
between 1 and 15 mils, most preferably between 3 and 10 mils.
[0067] U.S. Pat. No. 5,911,904 to Shih et al; U.S. Pat. No.
5,993,705 to Grischchenko et al.; and U.S. Pat. No. 6,085,970 to
Sadlier, although directed toward distinct insulating container
coatings and fabrication processes from that of the present
invention, generally describe many of the manufacturing coating,
heating and assembling processes that are commonly utilized in the
paper cup/container stock art. The complete details of these
coatings, heating and assembling processes are herein incorporated
by reference in the present application.
[0068] The preferred embodiments depicted in the accompanying
figures are directed toward the application of a foam layer 3
toward or along the interior surface of a container (e.g.,
beverage-side of the container). However, it will be appreciated by
one of ordinary skill in the art that the foam layer 3 can be
alternatively, or in combination with the PE film layer 4, applied
along the exterior surface of the container.
[0069] The inventors of the present invention have discovered
highly favorable, and heretofore unexpected, results when testing
was conducted of the various preferred embodiments of the present
invention. For example, a beverage container 10 constructed with a
container wall 1 having the construction shown in FIG. 3 has
demonstrated extraordinary hold times, moisture inhibition and
resistance to vapor transmission. Further, the inventors of the
present invention have demonstrated that hold times are
significantly increased with the embodiment shown in FIG. 3 as
compared to providing a moisture foam layer 3 blown on the outside
surface of the paper stock 2, such as the PerfecTouch.TM. cup sold
by Georgia Pacific.TM..
[0070] As aforementioned, a quantitative measurement of the ability
of a paper stock to withstand heat transfer between the beverage
containing space and the outermost surface of the container is
often referred to as hold time. Accordingly, how long one can
comfortably hold the hot container 10, e.g., hold time, is
significantly reduced.
[0071] The preferred embodiment shown in FIG. 3 appears to best
inhibit heat transfer to the paper stock 2, thereby reducing heat
transfer by providing a moisture vapor transmission barrier at the
innermost surface which prevents heating by mass transfer of that
vapor through the cupstock. Hold times were significantly increased
with the preferred embodiments of the present invention.
[0072] FIG. 7 is a graphical view of experimental data representing
actual and comparative hold times for embodiments of the present
invention and commercial available products and will be discussed
further hereinafter. FIG. 8 is a cross sectional view of an
insulating beverage container sleeve 12 according to the present
invention. FIG. 8 is a cross-sectional view of an insulated
beverage container wall 1 or beverage container sleeve wall 1
according to another embodiment of the present invention.
[0073] It will be appreciated that an insulating beverage container
sleeve 12 can readily incorporate any of the applicable embodiments
of beverage container stock material (container wall) 1 shown in
the accompanying drawings. An insulating beverage container sleeve
12 is often slipped over the outer surface of a beverage container
such as that shown in FIG. 1. As seen in FIG. 9, an intermediate
layer 5 may be provided between the paper stock 2 and foam layer 3.
The intermediate layer 5 is applied to the paper stock as an
extrusion, lamination, or coating. The purpose of the intermediate
layer 5 is to adhere the gas containing film layer 3 to the paper
stock 2.
[0074] However, the intermediate layer 5 can also be utilized as a
barrier to moisture transmission and as an aid in seam sealing
during sleeve construction. Typical materials used for intermediate
layer 5 include, but are not limited to: high density polyethylene
(HDPE), low density polyethylene (LDPE), linear low density
polyethylene (LLDP), orientated polypropylene(OPP); and adhesives,
such as hot melt adhesives, water based adhesives and solvent based
adhesives, etc.
[0075] Additives known in the industry may be included to enhance
certain properties or aid in processing and may include, but are
not limited to: ethylene vinyl acetate (EVA), ethylene vinyl
alcohol (EVOH), and plasticizers. Exterior layer 4 is applied to
the paper stock to provide a surface which may have the following
properties depending on end use, including but not limited to:
materials accepting high quality graphics and printing inks,
materials providing tactile feel, materials that change color with
temperature, materials providing seam sealing capabilities, and
materials providing a more secure gripping surface, etc. The sleeve
12 construction may be preferentially oriented with the foam
material 3 toward the cup 11 surface and the paper surface 2, 4
facing outward, e.g., visible to the user. However, the sleeve
construction can be inverted with the foam on the exterior and the
paper surface(s) 2, 4 facing inwardly toward the cup/container 11
wall. A PE layer as aforementioned can also be applied (not shown
in FIG. 9) along the interior surface of the container, e.g.
between the foam layer 3 and the beverage containing space 11 when
the embodiment of FIG. 9 is applied to a container 10.
[0076] FIG. 7 is a graphical view of experimental data representing
actual and comparative hold times for embodiments of the present
invention and commercial available products. FIG. 7 shows
experimental hold times (measured in seconds) achieved for
different samples. The various samples or beverage containers were
filled with approximately 230 ml of water at approximately
90.degree. C. (194.degree. F. pour temperature).
[0077] In Table I, Sample S2 is a product/container sample having
15/15/15 pt. base stock/air w/corrugation/base stock. Sample S5,
Sample S6, and Sample S7 are test samples of the present invention
incorporating a container wall 1 with construction similar to that
shown in FIG. 3. Sample S5 is a 10 pt foam 18 pt base paper
laminate. S6 is a 20 point foam 18 pt base paper laminate. S7 is a
30 pt foam 18 pt base paper laminate. Sample S9 is a paper stock
with a moisture blow polyethylene exterior such as the
PerfecTouch.TM. container available from Fort James. Sample S12 is
a laminate foam 18 pt base with 20 pt polyethylene foam.
[0078] Testing was conducted of different samples to determine
average hold times after several iterations of testing. A control
test person was used in many testing results to maintain data
integrity. In alternative testing, several different control test
persons were utilized.
[0079] Table I provides experimental test results of insulated cup
hold time studies conducted at a pour temperature of 90.degree. C.
and with approximately 230 ml. of water. Table I is directed toward
the test results of the various samples.
[0080] Anti-Wrinkling Effects
[0081] Paper stock-based laminates may suffer from wrinkling or
creasing of the innermost layers of a final product after
manufacture. For example, a beverage container 11 or sleeve 12
utilizing a foam layer 3 along the interior may experience a
particularly problematic wrinkling effect. During a cup making
process, blanks for cups are often die cut and then shaped around a
cylindrical mandrel. Accordingly, the cup diameter will vary
depending on the substrate thickness or caliper of each layer of
the laminate, the number of layers and the type of materials
utilized in each layer. Accordingly, the change in cup diameter,
.DELTA.D, can be quantified according to the following
relationship, wherein C is the substrate thickness or caliper,
.DELTA.D=2 C. However, as seen in FIG. 1, the diameter will also
vary depending on where it is measured, e.g. the diameter along the
upper side surface 7 is greater than that along the lower side
surface 8.
1TABLE I Insulated Cup Hold Time Study Pour Temperature - 90 C. All
Cups contained 230 ml. H2O 2 5 6 7 9 12 Sample Insu- 10 pt Foam CA-
CA- Product 10 pt w/ Number lair .TM. 18 pt Base 20 30 Sample 18 pt
base Hold Times in seconds Caliper 32.5 37 43.5 27.5 1/2 thou-
sandths of an inch Hold Times Average: 53.5 85.1 73.1 94.1 29.6
55.8 minus ctrl: 45.0 76.6 64.6 85.6 21.1 47.3 minus Perf 23.9 55.5
43.4 64.5 0.0 26.1 touch: minus 0.0 31.6 19.6 40.6 -23.9 2.3
Insulair .TM.:
[0082] Accordingly, the thicker the substrate, the greater the
difference between the innermost and outermost diameters. Since
both surfaces of the substrate start out at the same length, the
difference in diameter creates a system that is under stress. The
cup forming substrate, such as a paper stock 2, has a relatively
large caliper. A foam layer 3 along the interior surface is
relatively soft and pliable. Therefore, the foam properties along
the interior surface, coupled with the change in diameter, cause
wrinkles to form under the stress (with less ability to withstand
the stress) of conforming to a relatively smaller diameter.
[0083] The cross-section shown in FIG. 3 is exemplary of a
container 10 having a PE layer 4, wherein the foam layer 3 is
sandwiched in between the paper stock layer 2 and the PE layer 4.
The cross-section shown in FIG. 4 is exemplary of an insulating
foam layer 3 adhered to the paperboard stock layer 2 by a PE layer
4 that may exhibit the aforementioned wrinkling effect. As seen in
FIG. 5, another embodiment includes at least two PE layers 4,
wherein an inner surface of the container employing this cross
section will also have a PE layer 4 closest to the beverage
container space 11.
[0084] FIG. 10 is a plan view depicting an interior and exterior of
a beverage container or sleeve wall according to another embodiment
of the present invention. FIG. 11 is a plan view depicting an
interior and exterior of a beverage container or sleeve wall
according to another embodiment of the present invention. These
wrinkles 20 or creases become undesirable and problematic in the
finished cup or sleeve. The folds in the wrinkles 20 tend to trap
the beverage in the cup causing staining and/or loss of product.
The wrinkling effect also detracts from the aesthetic value of the
finished product.
[0085] FIGS. 10-11 are also directed toward a method of making a
beverage container or sleeve that eliminates or substantially
reduces the amount of wrinkling occurring along a container's
interior 30. FIGS. 10 and 11 depict the interior cup surface 30 and
exterior cup surface 40 of a container before and after heating and
shrinking the polymer shrink film layer (PE layer) 4, respectively,
according to an embodiment of the present invention. In FIG. 10 the
foam layer 3 has wrinkled under the stresses of conforming to a
smaller diameter. After being subjected to a heating process, the
foam shrinks, producing a taut, smooth layer as shown in FIG.
11.
[0086] During high speed cup forming, die cut paper may be wrapped
around a mandrel to form the container cylinder. Due to the
relative change in diameter, the inner surface 30 is now under
stress. By choosing a foam layer 3 that has shrink properties, the
wrinkles can be removed through the application of heat. A formed
cup with a wrinkled interior can be exposed to heat, causing the
foam to shrink and remove the wrinkles 20. As long as sufficient
heat is applied to smooth out the wrinkles while not overheating
the film to cause degradation, the specific details of the heat
application method are not critical. In an ideal embodiment, the
heating method and/or equipment can be incorporated into existing
cup making equipment.
[0087] The heating process can include localized heating or
shrinking processes, e.g., only the interior surface is subjected
to a heating process, such as heated process air being passed
exclusively along the interior surface 30. However, one of skill in
the art will appreciate that the entire container or various ratios
of controlled heating may be employed, e.g., interior surface
heating rate to exterior surface heating rate being increased so
that an interior to exterior ratio is generally higher than
1:1.
[0088] The elimination of wrinkles 20 can be accomplished with any
combination of heating and/or the incorporation of polymers for the
foam layer 3 and polymer shrink film layer 4 having desirable heat
shrink properties. The air used to transport and stack the finished
cups can be heating, the forming mandrels can be heated, the cup
can be transported through a tunnel heater or other heating device,
and/or a heated air stream can be passed across the cup's interior
surface 30.
[0089] Shrink films can be made out of a wide range of commercially
available polymers. Table II lists some applicable shrink-films
commercially available in the United States. However, one of skill
in the art will appreciate that other commercially available films
are available or are currently being developed. Accordingly, any
shrink film having desirable shrink film properties for the present
invention is within the spirit and scope of the present invention.
The polymers chosen and the polymer processing history are two
major factors influencing the foam shrink properties. The polymer
type and processing method should be selected to create the amount
of shrinkage necessary while maintaining foam integrity. The Wiley
Encyclopedia of Packaging Technology, Second Edition, Aaron L.
Brody and Kenneth S. Marsh, John Wiley and Sons, 1997, describes
additional examples of suitable shrink films and their related
properties, the entirety of which is hereby incorporated by
reference.
2TABLE II Commercially Available Shrink Films Shrink Film Polymer
Type Commercial Product Polyethylene Monolayer Polyolefins DuPont
Clysar HP, LLP; and Cryovac D601 Polyethylene Multilayer
Polyolefins Cryovac D955, D940, RD106, D959 Polypropylene/monolayer
Polyolefins DuPont Clysar EHC, CHS, ethylene--ropylene RSW; Okura
Vanguard copolymer 100; and Gunze PSS PP/EPC Multilayer Polyolefins
Cryovac MPD2055, MPD2100, J960, J961; Okura Vanguard 501; Intertape
Exlfilm IP-83; and Dupont Clysar EZ Biaxially Oriented Polyvinyl
Reynolds Reynolon 1044, Chloride (PVC) 2044, 3044, 4044, 5044;
Allied Krystaltite T111, T122, T133, T144, T15, R11, R22, R44, and
Gunze Fancywrap Preferentially Oriented Polyvinyl Reynolds Reynolon
3023, Chloride (PVC) 4061, 5032, 7052; and Allied Krystaltite PT152
Aroma and Oxygen Barrier Specialty Films Cryovac BDF200 1, BDF2050
Moisture Barrier Specialty Films Cryovac BDF1000 Moisture, Gas and
Aroma Specialty Films Cryovac BDF 3000 Barrier
[0090] Preferred shrink films for the present invention,
particularly polyethylene and/or modified polyethylene films, are
determined by their properties and cost. Specific examples of
shrink films for the foam layer 3 of the present invention are high
density polyethylene or blends of HDPE and linear low density
polyethylene (LLDPE), e.g., not more than 30% by weight. The shrink
films are created by stretching the warm film and keeping it under
tension while cooling. The polymer chains are then locked into a
stressed state. Upon being subjected to a heating process near the
melting point of the shrink film, the chains relax and the film
shrinks.
[0091] In a preferred embodiment, required "percent shrink" is low
relative to shrink films commercially marketed under this category.
Typical shrink films will shrink on the order of 70-80% if
unrestrained. The present inventors have determined that too much
shrinkage of the foam layer 3 will cause the film to pull away from
the container wall 11 and/or delaminate. Further, too much
shrinkage will result in undesired interior cup space loss and
reduced stacking efficiencies. The present inventors have
determined that a foam layer 3 having a percent shrink of between
0-30%, and more preferably a percent shrink of 5-10%, will create
the best results. Films with higher shrinkage rates may be used if
additional considerations are taken to control the shrinkage of the
container, such as controlling shrinkage through the use of an
inserted mandrel or other physically limiting device.
[0092] The shrink initiation temperature is another key attribute
of a preferred shrink film. A shrink film can be designed to shrink
at 190.degree. F., such as when hot coffee is poured into a
container thereby causing wrinkles 20 to be pulled or smoothed out
under tension. In addition, a shrink film can be selected that
shrinks at a temperature well above 190.degree. F., such as during
a relatively high manufacturing process temperature so that
wrinkles are removed prior to the actual use of the container. If
the initiation temperature is low, the total amount of shrinkage
must also be low. For example, if the initiation temperature is
190.degree. F., and 200.degree. F. coffee is poured into the cup,
the shrinkage must be low to avoid cup volume loss and expulsion of
hot coffee as the volume decreases.
[0093] A method of producing an insulated container may include the
steps of providing a paper cupstock having a container wall 1 for
surrounding an interior space 11, a bottom portion 9, and a paper
stock layer 2 arranged along an exterior surface 40 of the
container wall 1; mixing a blowing agent into a foamable polymer
layer 3; forming a foam layer 3 along an inside surface 30 of the
interior space 11; adhering a polymer shrink film layer 4, e.g., PE
layer 4, to the foam layer 3; and heat treating the container to
shrink the polymer shrink film layer between a percent shrink range
of 30% or less. The foam layer 3 is adhered to the paper cupstock
2, either directly or indirectly through another intermediate layer
5, e.g. such as an additional PE layer 4.
[0094] The aforementioned method of producing an insulated food or
beverage container or sleeve, may also include the steps of
providing an insulated container or sleeve having an interior space
11, the interior space 11 including a polymer shrink film layer 4
and a foam layer 4 along an interior surface 30 thereof. The
interior surface 30 is heated to shrink the polymer shrink film
layer 20 and remove wrinkles along the foam layer(s) 3 and polymer
shrink film layer(s) 4 during the heating step to thereby prevent
an undesirable wrinkling effect in the interior space 30.
[0095] The heat treatment process is employed either during the
manufacturing process or during product use, e.g., hot cup of
coffee produces desired shrinkage for shrinking the foam layer to
remove wrinkles at a percent shrink range of 30% or less. The heat
treatment process may also be any conventional heat treatment
process for shrinking polymer shrink films available in the related
art. This includes both heating and cooling processes, including
combinations thereof. The Wiley Encyclopedia of Packaging
Technology, Second Edition, Aaron L. Brody and Kenneth S. Marsh,
John Wiley and Sons, 1997, describes specific examples of heat
treatment processes for implementing shrink films, the entirety of
which is hereby incorporated by reference. Specifically, the
present invention may utilize conventional heat treatment processes
such as a tenter-frame process, a bubble process, combinations
thereof and/or their equivalents.
[0096] The invention being thus described, it will be obvious that
the same may be varied in many ways. Such variations are not to be
regarded as a departure from the spirit and scope of the invention,
and all such modifications as would be obvious to one skilled in
the art are intended to be included within the scope of the
following claims.
* * * * *