U.S. patent application number 13/924983 was filed with the patent office on 2014-12-25 for foamed film packaging.
The applicant listed for this patent is THE PROCTER & GAMBLE COMPANY. Invention is credited to Emily Charlotte Boswell, Michael Remus, Neil John Rogers.
Application Number | 20140376835 13/924983 |
Document ID | / |
Family ID | 51059661 |
Filed Date | 2014-12-25 |
United States Patent
Application |
20140376835 |
Kind Code |
A1 |
Rogers; Neil John ; et
al. |
December 25, 2014 |
Foamed Film Packaging
Abstract
A package includes at least one layer of foamed thin film having
gaseous bubbles, void volumes, or cells. The foamed thin film
includes a bio-based content of between about 10% and about 100%, a
caliper of between about 10 and 250 microns, and a density
reduction of between about a 5% to 50%, as compared to a non-foamed
thin film of substantially the same caliper that does not comprise
gaseous bubbles, void volumes, or cells.
Inventors: |
Rogers; Neil John; (Vivorde,
BE) ; Remus; Michael; (Heidelberg, DE) ;
Boswell; Emily Charlotte; (Cincinnati, OH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
THE PROCTER & GAMBLE COMPANY |
CINCINNATI |
OH |
US |
|
|
Family ID: |
51059661 |
Appl. No.: |
13/924983 |
Filed: |
June 24, 2013 |
Current U.S.
Class: |
383/207 ;
383/105 |
Current CPC
Class: |
B32B 27/065 20130101;
B32B 2264/102 20130101; B32B 2266/025 20130101; B32B 2553/00
20130101; B32B 2307/41 20130101; B32B 5/18 20130101; B32B 27/20
20130101; B65D 75/5827 20130101; B65D 75/5838 20130101; B32B 27/32
20130101; B32B 9/02 20130101 |
Class at
Publication: |
383/207 ;
383/105 |
International
Class: |
B65D 77/38 20060101
B65D077/38; B65D 33/00 20060101 B65D033/00 |
Claims
1. A package comprising at least one layer of foamed thin film
having gaseous bubbles, void volumes, or cells, wherein the layer
of foamed thin film comprises: i. a bio-based content of between
about 10% and about 100%; ii. a caliper of between about 10 and 250
microns; and iii. a density reduction of between about a 5% to 50%,
as compared to a non-foamed thin film of substantially the same
caliper that does not comprise gaseous bubbles, void volumes, or
cells.
2. The package of claim 1, wherein the package further comprises an
opening feature selected from the group consisting of: a line of
weakness and a die cut that defines a dispensing opening, formed in
the layer of foamed thin film.
3. The package of claim 1, wherein the layer of foamed thin film
comprises a bio-based content of between about 50% and about
100%.
4. The package of claim 1, wherein the bio-based content comprises
between about 5% and about 96% of bio-identical materials.
5. The package of claim 1, wherein the bio-based content comprises
between about 5% and about 50% of bio-new materials.
6. The package of claim 1, wherein the bio-based content is sourced
from a renewable resource.
7. The package of claim 1, wherein the package comprises synthetic
polymers derived from a renewable resource via an indirect route
with an intermediate compound comprising sugar or vegetable
starch.
8. The package of claim 1, wherein the package comprises polymers
derived directly from renewable resources and the polymers are
selected from a group consisting of: cellulose, starch, poly(lactic
acid), and polyhydroxyalkanoates.
9. The package of claim 2, wherein the opening feature comprises a
line of weakness.
10. The package of claim 1 wherein the package comprises a foamed
thin film co-extrusion that includes at least one foamed thin film
layer.
11. The package of claim 10, wherein the foamed thin film
co-extrusion comprises a top layer, a core layer, and a lower
layer, wherein the core layer is a foamed thin film layer.
12. The package of claim 1, wherein the package comprises a foamed
thin film laminate that includes at least one foamed thin film
layer.
13. The package of claim 12, wherein the foamed thin film laminate
comprises a top layer, a core layer, and a lower layer, wherein the
core layer is a foamed thin film layer.
14. A package comprising at least one layer of foamed thin film
having gaseous bubbles, void volumes, or cells, wherein the layer
of foamed thin film comprises: i. a bio-based content of between
about 10% and about 100%; ii. a caliper of between about 10 and 250
microns; iii. a whitening additive; and iv. a density reduction of
between about a 5% to 50%, as compared to a non-foamed thin film of
substantially the same caliper that does not comprise gaseous
bubbles, void volumes, or cells; wherein the whitening additive is
selected to produce a foamed thin film having an opacity value of
between about 35-99%.
15. The package of claim 14, wherein the package further comprises
an opening feature selected from the group consisting of: a line of
weakness and a die cut that defines a dispensing opening, formed in
the layer of foamed thin film.
16. The package of claim 14, wherein the layer of foamed thin film
comprises a bio-based content of between about 50% and about
100/%.
17. The package of claim 14, wherein the bio-based content
comprises between about 5% and about 96% of bio-identical
materials.
18. The package of claim 14, wherein the bio-based content
comprises between about 5% and about 50% of bio-new materials.
19. The package of claim 14, wherein the bio-based content is
sourced from a renewable resource.
20. The package of claim 14, wherein the package comprises
synthetic polymers derived from a renewable resource via an
indirect route with an intermediate compound comprising sugar or
vegetable starch.
21. The package of claim 14, wherein the package comprises polymers
derived directly from renewable resources and the polymers are
selected from a group consisting of: cellulose, starch, poly(lactic
acid), and polyhydroxyalkanoates.
22. The package of claim 14, wherein the whitening agent comprises
titanium dioxide.
23. The package of claim 15, wherein the opening feature comprises
a line of weakness.
24. The package of claim 14, wherein the package comprises a foamed
thin film co-extrusion that includes at least one foamed thin film
layer.
Description
FIELD OF THE INVENTION
[0001] This application relates to the field of packages comprising
a foamed film layer, and more specifically, to the field of
packages that comprise a foamed film layer made at least in part of
renewable, recyclable and/or biodegradable materials.
BACKGROUND OF THE INVENTION
[0002] Polyolefin-based plastic film is used to construct a wide
variety of packages such as bags, pouches, labels and wraps that
hold consumer goods. For example, bags holding stacks of disposable
diapers or hygiene articles, pouches for wet wipes, and bags
containing granular laundry detergent are often made from plastic
film. The plastic film that forms a package may be a single layer
of film (called a monofilm), or a combination of layers that can be
co-extruded, fabricated as a laminate of separately produced layers
that are adhered to one another, or fabricated as an extrusion
lamination whereas one layer is extruded onto another previously
formed layer(s).
[0003] The specific compositions of the film or films that make up
the package are selected for a variety of characteristics including
liquid or gas permeability, appearance and strength. Another
relevant characteristic of plastic film used for packaging is
opacity. The level of opacity of the plastic film used in a package
impacts the appearance of the package by controlling the extent to
which the package's contents are visible through the package. In
some circumstances, a higher opacity film may be desirable to
protect the contents from exposure to light. Additives such as
titanium oxide or other white or colored pigments are mixed with
the resin for the purpose of increasing the opacity of a film. In
general, decreasing the amount of resin in a film by making the
film thinner will in turn reduce its opacity.
[0004] Many plastic film packages include opening features, such
as, for example, lines of weakness and/or peelable labels covering
die cut openings. These lines of weakness and/or peelable labels
covering die cut openings are configured to provide convenient
consumer access to the contents of the package while maintaining
the integrity of the unopened package during shipment and storage.
Lines of weakness, such as perforations or scores, provide a
mechanism by which the consumer can, in a controlled manner, tear
open a package along a predetermined opening trajectory. The label
and die cut dispensing opening combination may be configured to
provide a re-sealable package for items that require retention of
moisture and/or other product ingredients within the package and/or
items for which it is desirable to exclude contamination. The die
cut defines the dispensing opening through which items are
dispensed. The label is sized to overlap the perimeter of the die
cut dispensing opening. The label tears the die cut from the
package the first time the label is peeled from the package. The
label may be capable of completely re-covering and re-sealing the
dispensing opening formed by the die cut.
[0005] Much of the cost associated with such plastic film packages
is the cost of the plastic resin that is used to make the film.
Because the amount of plastic resin in the film is directly related
to the caliper (or thickness) of the film, efforts to reduce cost
in plastic film packages typically involve using a lower caliper
film that can still provide the necessary characteristics for a
particular package. Because lower caliper film is typically weaker
in terms of inherent film tear strength, changing to a lower
caliper film in packages that includes an opening feature (e.g.,
lines of weakness or die cut dispensing openings) requires a
redesign of the opening feature to compensate for the lower tear
strength of the film. For example, the cuts in a line of
perforations may be made shorter to leave more film intact between
the cuts to resist unintentional tearing of the line of
perforations. Scores in the film may be made shallower to provide
additional strength to resist unintentional tearing of a lower
caliper film. Film connections between the cuts that define a die
cut may be made longer to resist unintentional separation of the
die cut from the film. The redesign of the opening feature is
costly in terms of engineering and evaluation time. In addition,
the redesign of the opening feature typically requires laborious
adjustments of various manufacturing components and processes that
create the opening feature on the film and possibly the purchase of
new tooling as well.
[0006] Recent technological developments have made it feasible to
produce foamed polyolefin film of suitable thickness (from about 10
microns to about 250 microns) and strength for the types of
packages described above. Several exemplary foamed polyolefin films
that are suitable for packages are described in European Patent No.
1 646 677. The use of foamed thin film allows for replacement of
part of the resin (e.g., from about 5% to about 50% by weight) with
gaseous bubbles that are formed or incorporated in the film during
a foaming process. Because the voids or cells left by the bubbles
occupy volume that was formerly filled with resin, foamed film
allows for a reduction in resin without a corresponding reduction
in film caliper. One notable feature of foamed thin films is that
they have a rough surface texture as compared to a non-foamed film
of substantially the same caliper.
[0007] Most of the materials used in fabrication of consumer
packaging applications are derived from non-renewable resources,
such as petroleum. Often, the components of consumer packages are
made from polyolefins, such as polyethylene, polypropylene, and
polyethylene terephthalate. These polymers are derived from
monomers, such as ethylene, propylene, and terephalic acid, which
are typically obtained directly from petroleum, coal and/or natural
gas via cracking and refining processes. The price and availability
of the petroleum/coal/natural gas feedstock therefore has a
significant impact on the price of consumer packages which utilize
materials derived from petroleum. As the worldwide price of
petroleum escalates, so does the price of polyolefin based
packaging. Moreover, many consumers display an aversion to
purchasing products that are packaged in materials derived from
petrochemicals. Other consumers may have adverse perceptions about
products derived from petrochemicals being "unnatural" or not
environmentally friendly.
[0008] Accordingly, it is of continued interest to provide consumer
packages which comprise at least one polymer that is at least
partially derived from renewable or recycled resources, where the
at least one polymer has specific performance characteristics
making the polymer particularly useful in consumer packaging. It
may also be desirable to provide renewable and/or recyclable
packaging that is also biodegradable.
SUMMARY OF THE INVENTION
[0009] In one aspect, a package includes at least one layer of
foamed thin film having gaseous bubbles, void volumes, or cells.
The foamed thin film includes a bio-based content of between about
10% and about 100%, a caliper of between about 10 and 250 microns,
and a density reduction of between about a 5% to 50%, as compared
to a non-foamed thin film of substantially the same caliper that
does not comprise gaseous bubbles, void volumes, or cells.
[0010] In one aspect, a package includes at least one layer of
foamed thin film having gaseous bubbles, void volumes, or cells.
The foamed thin film includes a bio-based content of between about
10% and about 100%, a caliper of between about 10 and 250 microns,
a whitening additive, and a density reduction of between about a 5%
to 50%, as compared to a non-foamed thin film of substantially the
same caliper that does not comprise gaseous bubbles, void volumes,
or cells. The whitening additive is selected to produce a foamed
thin film having an opacity value of between about 35-99%.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1a is cross section view of a prior art thin film that
can be used to construct thin film packages with an opening
feature.
[0012] FIG. 1b is a cross section view of a foamed thin film that
can be used to construct foamed thin film packages with an opening
feature in accordance with one or more embodiments of the present
invention.
[0013] FIG. 2a is a cross section view of a prior art thin film
co-extrusion that can be used to construct packages with an opening
feature.
[0014] FIG. 2b is a cross section view of a foamed thin film
co-extrusion that can be used to construct packages with an opening
feature in accordance with one or more embodiments of the present
invention.
[0015] FIG. 3a is a cross section view of a prior art thin film
laminate that can be used construct packages with an opening
feature.
[0016] FIG. 3b is a cross section view of a foamed thin film
laminate that can be used to construct packages with an opening
feature in accordance with one or more embodiments of the present
invention.
[0017] FIGS. 4a and 4b are perspective views of a package with a
line of weakness constructed in accordance with one or more
embodiments of the present invention.
[0018] FIG. 5 is a top plan view of a package with a label and die
cut dispensing opening constructed in accordance with the present
invention.
[0019] FIG. 6 is an exploded fragmentary cross section view of the
package of FIG. 5.
DETAILED DESCRIPTION OF THE INVENTION
[0020] As used herein, the following terms have the following
meanings:
[0021] "Agricultural product" refers to a renewable resource
resulting from the cultivation of land (e.g., a crop) or the
husbandry of animals (including fish).
[0022] "Bio-based content" refers to the amount of carbon from a
renewable resource in a material as a percent of the mass of the
total organic carbon in the material, as determined by ASTM
D6866-10, Method B. Note that any carbon from inorganic sources
such as calcium carbonate is not included in determining the
bio-based content of the material.
[0023] "Biodegradation" refers to a process of chemical dissolution
of materials by microorganisms or other biological means.
[0024] "Bio-identical polymer" refers to polymers that are made
from monomers where at least one monomer is derived from renewable
resources. For instance, a bio-identical polyolefin is made from
olefins that are derived from renewable resources, whereas a
petro-based polyolefin is made from olefins typically derived from
non renewable oil or gas.
[0025] "Bio-new polymer" refers to polymers that are directly
derived (i.e., no intermediate compound in the derivation process)
from renewable resources. Such renewable resources include
cellulose (e.g. pulp fibers), starch, chitin, polypeptides,
poly(lactic acid), polyhydroxyalkanoates, and the like.
[0026] "Microorganism" is defined as an organism that is too small
to see with the naked eye, such as bacteria, fungi, archaea, and
protists.
[0027] "Monomeric compound" refers to an intermediate compound that
may be polymerized to yield a polymer.
[0028] "Petrochemical" refers to an organic compound derived from
petroleum, natural gas, or coal.
[0029] "Petroleum" refers to crude oil and its components of
paraffinic, cycloparaffinic, and aromatic hydrocarbons. Crude oil
may be obtained from tar sands, bitumen fields, and oil shale.
[0030] "Polymer" refers to a macromolecule comprising repeat units
where the macromolecule has a molecular weight of at least 1000
Daltons. The polymer may be a homopolymer, copolymer, terpolymer,
etc. The polymer may be produced via fee-radical, condensation,
anionic, cationic, Ziegler-Natta, metallocene, or ring-opening
mechanisms. The polymer may be linear, branched and/or
cross-linked.
[0031] "Polyethylene" and "polypropylene" refer to polymers
prepared from ethylene and propylene, respectively. The polymer may
be a homopolymer, or may contain up to about 10 mol % of repeat
units from a co-monomer.
[0032] "Polymers derived directly from renewable resources" refer
to polymers obtained from a renewable resource without
intermediates. Typically, these types of polymers would tend be
"bio-new".
[0033] "Post-consumer recycled polymers" refer to synthetic
polymers recovered after consumer usage and includes recycled
polymers from plastic bottles (e.g., laundry, milk, and soda
bottles).
[0034] "Renewable resource" refers to a natural resource that can
be replenished within a 100 year time frame. The resource may be
replenished naturally, or via agricultural techniques. Renewable
resources include plants, animals, fish, bugs, insects, bacteria,
fungi, and forestry products. They may be naturally occurring,
hybrids, or genetically engineered organisms. Natural resources
such as crude oil, coal, and peat which take longer than 100 years
to form are not considered to be renewable resources.
[0035] "Synthetic polymer" refers to a polymer which is produced
from at least one monomer by a chemical process. A synthetic
polymer is not produced directly by a living organism. Synthetic
polymers of the present disclosure can be derived from a renewable
resource via an indirect route involving one or more intermediate
compounds. Typically, these types of polymers would tend to be
"bio-identical", although not all of them are.
[0036] "Thin film" is defined as a film having a caliper that is
suitable for use in packages such as bags, pouches, labels and
wraps for consumer goods, such as, for example, film calipers from
about 10 to about 250 microns. As used herein, the term "foamed
thin film" designates a film containing at least one layer having a
caliper from about 10 microns to about 250 microns and that
comprises gaseous bubbles, void volumes, or cells wherein that the
at least one layer exhibits a density reduction of at least about
5% by yield (as determined by ASTM D4321) versus a film of the same
thickness that does not comprise gaseous bubbles, void volumes, or
cells.
[0037] A package and a method of constructing a package that
includes at least one layer of foamed thin film which comprise at
least one polymer that is at least partially derived from renewable
or recycled resources, wherein the package includes an opening
feature formed in the at least one layer of foamed thin film, is
provided herein. The foamed thin film has a caliper of from about
10 microns to about 250 microns thick. The foamed thin film
comprises from about 5% to about 50% density reduction as compared
to a non-foamed thin film of substantially the same composition and
caliper.
[0038] The opening feature may include a line of weakness.
Advantageously, the line of weakness may be of substantially the
same configuration as a line of weakness configured for use in a
non-foamed thin film of substantially the same composition and
caliper. The yield stress value of the at least one layer of foamed
thin film with the line of weakness may be at least about 90% of
the yield stress value of the foamed thin film without the line of
weakness. The opening feature may be, for example, in the form of
perforations, scores, or embossments.
[0039] Alternatively, the opening feature may include a die cut
dispensing opening and a label adhered to the die cut such that the
label overlaps an opening defined by the die cut. In this case, the
label has adhesive applied to a first side whereby the label is
adhered to the die cut and peelably adhered to the foamed thin film
about a periphery of the opening. Advantageously, the adhesive may
be of substantially the same composition as adhesive configured for
use on a non-foamed thin film of substantially the same composition
and substantially the same caliper.
[0040] The package may comprise a monolayer foamed film, or
multiple layers where at least one layer is foamed. A package may
include a foamed thin film co-extrusion that includes at least one
foamed thin film layer. A package may include a foamed thin film
laminate that includes at least one foamed thin film layer. The
foamed thin film layer may be, for example, blown, cast, biaxially
oriented cast, post film formation process oriented (i.e.,
stretched, drawn or tentered) in the cross or machine orientated
direction, foamed polyethylene or foamed polypropylene.
[0041] The opening feature in the foamed thin film may be formed by
weakening a selected opening trajectory or path on the foamed thin
film by non-contact means (e.g. laser, spark arcs) or mechanically
via a blade, punch or pin or by weakening the selected opening
trajectory with a deforming profile.
[0042] A package may include at least one layer of foamed thin film
made of a plastic resin and a whitening or coloring additive that
is added to the plastic resin. The resin could be a traditional
petro-based polyolefin, or it could be a renewable based
polyolefin, or a blend thereof. Alternatively it could be a blend
comprising a petro-based or renewable based polyolefin blend mixed
with a renewable "bio-new" material that is chemically different to
traditional petro-based polyolefins. The film could be comprised of
a material or mixture of materials having a total bio-based content
of about 10% to about 100% using ASTM D6866-10, method B.
[0043] In one embodiment, the package comprises from about 5% to
about 99% by weight of a polymer (A). Polymer (A) comprises at
least one or possibly more of a low density polyethylene (LDPE), a
polar copolymer of polyethylene such as ethylene vinyl acetate
(EVA), a linear low density polyethylene (LLDPE), a high density
polyethylene homopolymer/high density polyethylene copolymer, a
medium density polyethylene, a very low density polyethylene
(VLDPE), a plastomer, a polypropylene/copolypropylene/heterophasic
polypropylene, polyethylene terephthalate (PET), PLA (e.g., from
Natureworks), polyhydroxyalkanoate (PHA),
poly(ethylene-2,5-furandicarboxylate) (PEF), cellulose (available
from, for example, Innovia), NYLON 11 (i.e., Rilsan.RTM. from
Arkema), starch (either thermoplastic starch or starch fillers),
bio-polyesters, (e.g., those made from bio-glycerol, organic acid,
and anhydride, as described in U.S. Patent Application No.
2008/0200591, incorporated herein by reference), polybutylene
succinate, polyglycolic acid (PGA), and polyvinyl chloride (PVC).
At least one of the constituents of polymer (A) is at least
partially derived from a renewable resource. Recycled materials may
also be in added. In specific cases, materials that are
biodegradable may be utilized. The whitening or coloring additive
is selected to produce a foamed thin film having an opacity value
of from about 35% to about 99%. The whitening agent is of
substantially the same composition and is present in substantially
the same amount as would be selected to produce substantially the
same light reflectivity in a non-foamed thin film of substantially
the same caliper and substantially the same composition. Some of
the "bio-new" materials may further contribute to increasing the
opacity of the film, as the presence of this additional material
within the film structure can lead to additional light
reflectivity, due to their typical incompatibility with the
polyolefin matrix. In addition to introducing renewable content and
opacity (depending on the exact blend), the addition of a "bio-new"
material in particular may modify the performance of the "easy
open" feature, depending on the exact type and % of "bio-new"
content.
Foamed Films
[0044] FIG. 1a is a cross section view of a thin film 100 that is
used in many packaging applications such as bags, pouches, labels
and wraps that hold consumer goods. Thin films 100 used in such
packages typically have a caliper (thickness) from about 10 microns
to about 250 microns and are made of a polyolefin resin. Many
different blends of components are used in the polyolefin and
components are selected for a variety of properties such as
strength and opacity. Polyethylene (e.g., Low Density Polyethylene
(LDPE), Linear Low Density Polyethylene (LLDPE), High Density
Polyethylene (HDPE), Medium Density Polyethylene (MDPE),
Metallocene Polyethylene (mPE), Ethyl Vinyl Acetate (EVA), cyclic
polyolefins, ionomers (Na+ or Zn+), elastomers, plastomers and
mixtures thereof) and polypropylene, and blends thereof are two
types of materials that are often used to manufacture thin films
100. LLDPE resins could be manufactured with co-monomers that are
either butane, hexene or octane. The catalysts used to produce
polymers could be Ziegerl-Natta based, Chromium based, metallocene,
single site or other type of catalyst. Thin films 100 can be
manufactured using blown film, cast film, cast biaxially stretched
film and extrusion base processes. A secondary post film formation
process could also be applied to films such as Machine Direction
Orientation, or other type of stretching in either one or two
directions. As can be seen in FIG. 1a, the thin film 100 is made up
of a substantially solid layer of resin. The thin film 100 shown in
FIG. 1a is called a monofilm because it consists of a single layer
of resin.
[0045] FIG. 2a is a cross section view of a thin film co-extrusion
200 that includes a top layer 210, a core 220, and a lower layer
230. Many film packages use thin film co-extrusions because the
composition of each layer may be selected to contribute a desired
quality to the resulting package. To produce a thin film
co-extrusion, resins for each layer are co-extruded while molten
and cooled together to form a layered thin film co-extrusion. As
can be seen in FIG. 2a, the thin film co-extrusion 200 includes
layers (e.g., the top layer 220, core layer 220, and lower layer
230) of each type of resin directly adjacent one another. Thin film
co-extrusions may include layers that are selected to provide, for
example, strength, opacity, print quality, and moisture resistance.
As can be seen in FIG. 2a, the thin film co-extrusion 200 includes
layers that are made up of substantially solid layers of resin.
[0046] FIG. 3a is a cross section view of thin film laminate 300
that includes a top layer 310, a top adhesive layer 315, a core
320, a bottom adhesive layer 325, and a bottom layer 330. Thin film
laminates 300 are similar to thin film co-extrusions 200 because
both include layers of different resins that are selected to
contribute a desired quality to the resulting package. However,
rather than being combined in a molten form, the layers of a thin
film laminate 300 are separately formed and cooled. Laminates are
often used when one or more of the layers is not well suitable for
co-extrusion, such as, for example, metalized layers that require
significantly different processing techniques as compared to
plastic layers. The separate layers (e.g., the top layer 310 the
core 320, and the bottom layer 330) are then fixed to one another,
such as, for example, using adhesive (e.g., the top adhesive layer
315 and the bottom adhesive layer 325). As can be seen in FIG. 3a,
the thin film laminate 300 includes layers that are made up of
substantially solid layers of resin.
[0047] FIGS. 1b, 2b, and 3b illustrate various foamed thin films
10, 20, 30 that are suitable for use in packaging applications. The
foamed thin films 10, 20, 30 each include at least one foamed
layer, 12, 23, 32, respectively. As discussed above, until
recently, thin films for use in packaging were not believed to be
suitable for foaming because of concerns about potential
degradations in tear strength that could be brought about by the
loss of resin content in a foamed film. EP 1 646 677 provides
details about specific resin compositions and processing steps that
enable the production of foamed thin films. The resin used in
making the foamed film may include renewable materials--either
"bio-identical" or "bio-new" materials. Some non-limiting options
of applicable bio-identical and/or bio-new materials are further
detailed below.
[0048] Referring to FIG. 1b, a foamed thin monofilm 10 made up of a
resin 12, such as, for example, polyolefin, in which gas bubbles 14
are entrapped is shown. One way to produce foamed monofilm 10 is
adding one or more chemical blowing agents such as, for example,
Sodium Hydro Carbonate Powder and an acidifier to the master batch
of resin 12 prior to heating. Upon heating, chemical blowing agents
release carbon dioxide. The carbon dioxide expands and forms
bubbles 14 in the monofilm 10 during subsequent processing steps.
One exemplary chemical equation describing the transition of the
blowing agent to carbon dioxide is:
NaHCO.sub.3(Sodium Hydro Carbonate
Powder)+H.sup.+(Acidifier).fwdarw.Na.sup.++CO.sub.2+H.sub.2O
[0049] Some of the carbon dioxide bubbles 14 escape the molten
resin 12 while others are trapped in the resin 12 during cooling to
form voids that remain after solidification of the resin. An
alternative to the use of chemical blowing agents that react in the
resin to produce bubbles 14 is to inject a gas such as carbon
dioxide or nitrogen into the molten plastic within the extruder
prior to it leaving the die, during film manufacture (such as
practiced in the Mucell process by the Trexel Corporation). While
the bubbles 14 shown in FIG. 1b are generally spherical in the melt
and have a diameter from about 1 micron to about 100 microns, other
shapes are contemplated. For example, in some solidified foamed
films, the bubbles are generally cigar shaped (in cross sectional
analysis) and oriented in the direction of film extrusion. In a
foamed thin polyethylene monofilm having a caliper of about 40
microns, a typical cigar shaped bubble may be about 10 microns in
diameter (typically <20 microns) and typically from about 50
microns to about 300 microns in length. The foam structure of a
foamed thin monofilm 10 is generally closed towards the surface
such that substantially all of the bubbles 14 close to the surface
are closed. Because the bubbles 14 occupy volume that would have
been occupied by resin 12 in a non-foamed thin film, the foamed
thin monofilm 10 in FIG. 1b uses less resin 12 than its non-foamed
counterpart 100 in FIG. 1a while maintaining substantially the same
overall thickness "t." Of course, other foaming methods may be
employed in the practice of the present invention, such as, for
example, through the incorporation of particles (e.g. CaCO3 or PS)
followed by stretching (uni-axial or bi-axial) of the film to
cavitate around the particles. We also contemplate that bubbles
with smaller dimensions could be formed with a particular selection
of materials.
[0050] FIG. 2b shows a foamed thin film co-extrusion 20 that
includes a foamed core 23 and a non-foamed top layer 25 and a
non-foamed bottom layer 27. While only the core 23 is shown as
foamed, any combination of layers in a foamed thin film
co-extrusion may be foamed, including the top layer 25, the bottom
layer 27, or the top layer 25 and the bottom layer 27, or all three
layers 23, 25, 27. In addition, the core 23 need not be foamed if
any other layer is foamed and any number of foamed and non-foamed
layers may be present in the foamed thin film co-extrusion. The use
of foamed thin film co-extrusions 20 is well suited for many
packaging applications because layers can be selected for tensile
strength, sealing properties, cost, and aesthetic impression. It
has been observed that in foamed thin film co-extrusions, foaming
in one layer is limited to the foamed layer. That is, foaming does
not appear to induce foaming in adjacent non-foamed layers.
[0051] By way of example, a bag adapted for storing large granules
is constructed of a thin film laminate that includes the thin film
co-extrusion 200 (FIG. 2a) as a base layer. This particular thin
film co-extrusion 200 is configured to present a white outer
surface on which a printed top layer (not shown) is applied while
creating a blue inner surface that enhances the appearance of the
white granules stored in the bag when viewing the granules through
the bag's opening. The top layer 210 of the thin film co-extrusion
200 is made of a white polyethylene film having a caliper of
approximately 15 microns that is adapted for improved interaction
with the printed top layer (not shown). The core 220 is made of a
white polyethylene film having a caliper of approximately 40
microns that is adapted to mask the blue color from the bottom
layer 230 from showing through. The bottom layer 230 is made of a
blue polyethylene film having a caliper of approximately 15 microns
that is adapted to present a visually appealing background for the
granules in the bag.
[0052] The foamed thin film co-extrusion 20 shown in FIG. 2b may be
used to replace the thin film co-extrusion 200. The foamed thin
film co-extrusion 20 includes a top layer 25 made of an extreme
white polyethylene film having a caliper of approximately 15
microns, a core 23 made of a foamed light white polyethylene film
having a caliper of approximately 40 microns, and a bottom layer
made of a blue polyethylene film having a caliper of approximately
15 microns. The foamed core 23 uses about half as much resin as the
non-foamed core (e.g., core 220 in FIG. 2a). To compensate for the
change in appearance caused by the presence of bubbles in the core
23, much of the white or colored pigment in the core 23 was removed
to reduce the contrast between bubble and resin. The white
intensity of the top layer was increased to achieve a comparable
appearance between the thin film co-extrusion 200 and the foamed
thin film co-extrusion 20. Of course, the development of a foamed
thin film co-extrusion to replace an existing thin film
co-extrusion may involve changing the caliper of different layers,
changing the material composition of different layers, and/or
adding or removing layers.
[0053] FIG. 3 illustrates a foamed thin film laminate 30 that
includes a foamed core 32 and a non-foamed top layer 35 and bottom
layer 39. While only the core 32 is shown as foamed, any
combination of layers in a foamed thin film laminate may be foamed,
including the top layer 35, a bottom layer 39, both top layer 35
and bottom layer 39, or all three layers 32, 35, 39. In addition,
the core 32 need not be foamed if any other layer is foamed and any
number of foamed and non-foamed layers may be present in the foamed
thin film laminate. The use of foamed thin film laminates 30 is
well suited for many packaging applications, especially for
packages that require a layer that is not readily co-extruded with
other layers in the foamed thin film laminate. It is believed that
the same types of adhesive (e.g., adhesives 315 and 325) used in
non-foamed thin film laminates may be used as adhesives (e.g.,
adhesives 33, 37) to adhere layers in foamed thin film
laminates.
Opening Features
[0054] As used herein, the term "opening feature" is defined as an
aid to opening of the package that includes a weakening of a
selected opening trajectory on the foamed thin film. Two examples
of such opening features are linear lines of weakness and die cut
dispensing openings with labels.
[0055] FIGS. 4a and 4b illustrate a bag 40 that includes walls of
foamed thin film 42 and a linear line of weakness 43. The line of
weakness 43 is configured to remain intact until opened by the
consumer along a linear opening trajectory as shown by the arrows
in FIG. 4b. The line of weakness 43 can be formed, for example,
from a line of scores that partially cut through the wall 42 of the
bag 40 or a line of perforations that completely cut through the
wall 42 of the bag 40. The lines of weakness 43 are of
substantially the same configuration as lines of weakness that are
configured for use in a bag (not shown) having non-foamed thin film
walls of substantially the same caliper. The lines of weakness can
be produced using methods including scoring and perforation. The
scoring or perforation may be performed using a laser or by
mechanical means. The methods and method parameters used to produce
the line of weakness 43 in a foamed thin wall (e.g., wall 42) are
substantially the same as methods used to produce a line of
weakness in a non-foamed thin wall of substantially the same
caliper.
[0056] One method of making a line of weakness uses at least one
laser. First a laser beam with sufficient wattage to evaporate a
portion of the film material is focused onto the thin film. The use
of laser technology allows for very accurate control of the depth
of penetration from very slight scoring to complete perforation of
the thin film. A laser using any form of electromagnetic radiation
can be used. Suitable lasers for making lines of weakness in thin
films include those based on CO.sub.2 gas.
[0057] Another suitable method for producing the lines of weakness
is the use of blades. The blades are installed on a cylinder, which
is mounted directly on the film processing machinery so that the
cuts are made prior to formation of the bag as the film travels
past the blade-equipped cylinder Different blade patterns can be
used to get different patterns in the line of weakness. The
pressure applied to the blades is also varied during the process to
control the dimensions and depth of the cuts to ensure the bag
opens easily.
[0058] Embossing is another alternative method for production of
lines of weakness. The embossing technology weakens the thin film
in specific areas by means of pressure, temperature, processing
time and a deforming profile. The desired results are achieved by
changing the caliper and/or material structure at the embossing
trajectory. The basic equipment used for embossing consists of a
sealing jaw capable of pressing against a back plate. A deforming
profile or pattern is fixed to the jaw and heated. The thin film is
pressed between the deforming profile and the back plate. The main
variables known to affect this process are: heating temperature,
cooling temperature, pressure, heating time, cooling time, film
tension while embossing, film tension after embossing, back plate
material, back plate thickness, back plate temperature, jaw pattern
and jaw thickness. The embossing unit is typically installed after
an unwinding station of the thin film and could be incorporated
into the packaging production line. EP 1 409 366 describes methods
of producing lines of weakness in non-foamed thin films in
detail.
[0059] Lines of weakness in foamed thin film (e.g., line of
weakness 43 in FIGS. 4a and 4b and die cut line of weakness 52 in
FIG. 5) may form many different patterns. Those patterns may take
the form of a continuous line, a dashed line, or combinations
thereof. One exemplary line of weakness is a dashed line 43 that
includes a plurality of scored segments 44. The length of each
scored segment 44 varies from about 0.12 mm to about 4.4 mm. The
distance of the connections or bridges 45 between adjacent scored
segments 44 varies from about 0.4 mm to about 4 mm. The score depth
may vary depending on the thickness of the foamed thin film.
Notably, any pattern that is suitable for use in a non-foamed thin
film wall will also be suitable for use in a foamed thin film wall
of substantially the same caliper.
[0060] Lines of weakness 43, 52 are designed to deteriorate the
strength of the foamed thin film in such a way that it can
withstand normal filling, packing and handling operation and yet be
easily opened by the consumer. This is achieved by reducing the
trapezoidal tear strength of the foamed thin film. Reduction of the
trapezoidal tear strength is also generally accompanied by loss of
tensile strength.
[0061] The line of weakness 43, 52 may be characterized using the
following test methods: a) ASTM D-882 Standard Test Method for
Tensile Properties on Thin Plastic Sheeting and b) ASTM D-5733
Standard Test Method for Tearing Strength of Nonwoven Fabrics by
the Trapezoidal Procedure. The line of weakness 43, 52 may be
characterized by three parameter values obtained from these
standard tests. The first is yield stress value. The yield stress
value of the foamed thin film with a line of weakness as measured
by ASTM D-882 should be no less than about 90% of the yield stress
value of the foamed thin film without a line of weakness. Second,
the final or rupture stress value of the foamed thin film with the
line of weakness should be no lower than about 90% of the yield
stress value of the foamed thin film without the line of weakness.
Third, the average trapezoidal tearing force according to ASTM
D-5733 of the foamed thin film with the line of weakness should be
less than about 4 kilograms of force.
[0062] FIG. 5 is a top plan view of a package 48 having at least
one foamed thin film wall 49. The package 48 includes a die cut
dispensing opening/label combination 50 that enables a user to
reseal the package 48 after dispensing items from the package 48. A
die cut line of weakness 52, which can be seen through the label 54
in FIG. 5, is formed in the foamed thin film wall 49. The die cut
line of weakness 52 may have a significantly larger proportion of
weakened foamed film material than the line of weakness 43 in FIGS.
4a and 4b. The die cut line of weakness 52 is shown having four
long perforations 52a-52d that are attached by relatively small
connections or bridges 52e-52h. The large proportion of weakened
foam film material in the die cut line of weakness means that very
little force will be required to completely separate a die cut 59
defined by the die cut line of weakness 52 from the foamed thin
film wall 49. A label 54 covers and overlaps the die cut 59. The
label 54 is adhered to the foamed thin wall 49 with, for example,
adhesive (of course other methods of adhesion can be used).
[0063] To dispense an item from the package 48, the consumer peels
an edge of the label 54 as indicated by the arrow in FIG. 5. In the
first use, the label 54 pulls the die cut 59 free from the foamed
thin wall 49 by rupturing the bridges 52e-52h. The die cut 59
remains adhered to an underside of the label 54 as shown in FIG. 6.
To reseal the package 48, the consumer re-adheres the label 54 to
the foamed thin wall 49.
[0064] FIG. 6 is an exploded cross section view of the die cut
dispensing opening/label combination 50 and the foamed thin wall
49. Adhesive 57 is shown on an underside of the label 54 with an
optional adhesive-free region 65 at a lead edge of the label 54
that defines a tab that can be gripped by a consumer. The die cut
59 defines a dispensing opening 67 through which items are
dispensed from the package 48. In other embodiments (not shown),
regions of different types of adhesive may be present on the
underside of the label and the die cut dispensing opening/label
combination may include intermediate layers disposed between the
package and the label.
[0065] The perforations (or scores) 52a-d (FIG. 5) that are used in
the die cut line of weakness 52 are produced according to the same
methods described above with respect to lines of weakness 43 (FIGS.
4a, 4b). As with the lines of weakness 43, the methods and method
parameters used to produce the die cut line of weakness 52 in a
foamed thin wall (e.g., wall 49) are substantially the same as
methods used to produce a die cut dispensing opening in a
non-foamed thin wall of substantially the same caliper. In addition
the adhesive that is used on the label 54 in a die cut dispensing
opening/label combination (e.g., die cut dispensing opening/label
combination 50) used on a foamed thin wall (e.g. the foamed thin
wall 49) is substantially the same as adhesive (e.g., the adhesive
57) that is used on a label used with a non-foamed thin wall of
substantially the same composition.
Polymers Derived from Renewable & Sustainable Resources
[0066] A number of renewable resources contain polymers that are
suitable for use in consumer packages (i.e., the polymer is
obtained from the renewable resource without intermediates).
Suitable extraction and/or purification steps may be necessary, but
no intermediate compound is required. Such polymers that are
derived directly from renewable resources include cellulose (e.g.
pulp fibers), starch, chitin, polypeptides, poly(lactic acid),
polyhydroxyalkanoates, and the like. We typically describe such
polymers as "bio-new" polymers. These polymers may be subsequently
chemically modified to improve end use characteristics (e.g.,
conversion of cellulose to yield carboxycellulose or conversion of
chitin to yield chitosan). However, in such cases, the resulting
polymer is a structural analog of the starting polymer. Any
polymers derived directly from renewable resources with no
intermediate compounds (and their derivatives) that are known in
the art may be useful herein. All of these materials are within the
scope of the present disclosure.
[0067] Synthetic polymers of the present disclosure can be derived
from a renewable resource via an indirect route involving one or
more intermediate compounds. Suitable intermediate compounds
derived from renewable resources include sugars, such as, for
example, monosaccharides, disaccharides, trisaccharides, and
oligosaccharides. Sugars such as sucrose, glucose, fructose and
maltose may be readily produced from renewable resources such as
sugar cane and sugar beets. Sugars may also be derived (e.g., via
enzymatic cleavage) from other agricultural products such as starch
or cellulose. For example, glucose may be prepared on a commercial
scale by enzymatic hydrolysis of corn starch. While corn is a
renewable resource in North America, other common agricultural
crops may be used as the base starch for conversion into glucose.
Wheat, buckwheat, arracaha, potato, barley, kudzu, cassava,
sorghum, sweet potato, yam, arrowroot, sago, and other similar
starchy fruit, seeds, or tubers may also be used in the preparation
of glucose.
[0068] Other suitable intermediate compounds derived from renewable
resources include monofunctional alcohols such as methanol or
ethanol and polyfunctional alcohols such as glycerol. Ethanol may
be derived from many of the same renewable resources as glucose.
For example, cornstarch may be enzymatically hydrolyzed to yield
glucose and/or other sugars. The resultant sugars can be converted
into ethanol by fermentation. As with glucose production, corn is
an ideal renewable resource in North America; however, other crops
may be substituted. Methanol may be produced from fermentation of
biomass. Glycerol is commonly derived via hydrolysis of
triglycerides present in natural fats or oils, which may be
obtained from renewable resources such as animals or plants.
[0069] Other intermediate compounds derived from renewable
resources include organic acids (e.g., citric acid, lactic acid,
alginic acid, amino acids etc.), aldehydes (e.g., acetaldehyde),
and esters (e.g., cetyl palmitate, methyl stearate, methyl oleate,
etc.). Additional intermediate compounds such as methane and carbon
monoxide may also be derived from renewable resources by
fermentation and/or oxidation processes.
[0070] Intermediate compounds derived from renewable resources may
be converted into polymers (e.g., glycerol to polyglycerol) or they
may be converted into other intermediate compounds in a reaction
pathway which ultimately leads to a polymer useful in a consumer
package. An intermediate compound may be capable of producing more
than one secondary intermediate compound. Similarly, a specific
intermediate compound may be derived from a number of different
precursors, depending upon the reaction pathways utilized.
[0071] Particularly desirable intermediates include olefins.
Olefins such as ethylene and propylene may also be derived from
renewable resources. For example, methanol derived from
fermentation of biomass may be converted to ethylene and or
propylene, which are both suitable monomeric compounds, as
described in U.S. Pat. Nos. 4,296,266 and 4,083,889. Ethanol
derived from fermentation of a renewable resource may be converted
into the monomeric compound ethylene via dehydration as described
in U.S. Pat. No. 4,423,270. Similarly, propanol or isopropanol
derived from a renewable resource can be dehydrated to yield the
monomeric compound of propylene as exemplified in U.S. Pat. No.
5,475,183. Propanol is a major constituent of fusel oil, a
by-product formed from certain amino acids when potatoes or grains
are fermented to produce ethanol.
[0072] Charcoal derived from biomass can be used to create syngas
(i.e., CO+H.sub.2) from which hydrocarbons such as ethane and
propane can be prepared (Fischer-Tropsch Process). Ethane and
propane can be dehydrogenated to yield the monomeric compounds of
ethylene and propylene.
[0073] Other sources of materials to form polymers derived from
renewable or sustainable resources include post-consumer recycled
materials. Sources of synthetic post-consumer recycled materials
can include plastic bottles (e.g., soda bottles), plastic films,
plastic packaging materials, plastic bags and other similar
materials which contain synthetic materials which can be
recovered.
[0074] In one aspect, the present disclosure is directed to films
having at least one layer of a composition comprising an intimate
admixture of a thermoplastic polymer and a wax having a melting
point greater than 25.degree. C. The wax can have a melting point
that is lower than the melting temperature of the thermoplastic
polymer. The wax can be present in the composition in an amount of
about 5 wt % to about 40 wt %, about 8 wt % to about 30 wt %, or
about 10 wt % to about 20 wt %, based upon the total weight of the
composition. The wax can comprise a lipid, which can be selected
from the group consisting of a monoglyceride, diglyceride,
triglyceride, fatty acid, fatty alcohol, esterified fatty acid,
epoxidized lipid, maleated lipid, hydrogenated lipid, alkyd resin
derived from a lipid, sucrose polyester, or combinations thereof.
The wax can comprise a mineral wax, such as a linear alkane, a
branched alkane, or combinations thereof. Specific examples of
mineral wax are paraffin and petrolatum. The wax can be selected
from the group consisting of hydrogenated soy bean oil, partially
hydrogenated soy bean oil, epoxidized soy bean oil, maleated soy
bean oil, tristearin, tripalmitin, 1,2-dipalmitoolein,
1,3-dipalmitoolein, 1-palmito-3-stearo-2-olein,
1-palmito-2-stearo-3-olein, 2-palmito-1-stearo-3-olein,
1,2-dipalmitolinolein, 1,2-distearo-olein, 1,3-distearo-olein,
trimyristin, trilaurin, capric acid, caproic acid, caprylic acid,
lauric acid, myristic acid, palmitic acid, stearic acid, and
combinations thereof. The wax can be selected from the group
consisting of: a hydrogenated plant oil, a partially hydrogenated
plant oil, an epoxidized plant oil, a maleated plant oil. Specific
examples of such plant oils include soy bean oil, corn oil, canola
oil, and palm kernel oil. The wax can be dispersed within the
thermoplastic polymer such that the wax has a droplet size of less
than 10 .mu.m, less than 5 .mu.m, less than 1 m, or less than 500
nm within the thermoplastic polymer. The wax can be a renewable
material.
[0075] In one aspect, the present disclosure is directed to films
having at least one layer of a composition comprising an intimate
admixture of a thermoplastic polymer and about 5 wt % to about 40
wt % of an oil, based upon the total weight of the composition,
wherein the oil has a melting point of 25.degree. C. or less and a
boiling point greater than 160.degree. C. The oil can comprise a
lipid, which can be selected from the group consisting of a
monoglyceride, diglyceride, triglyceride, fatty acid, fatty
alcohol, esterified fatty acid, epoxidized lipid, maleated lipid,
hydrogenated lipid, alkyd resin derived from a lipid, sucrose
polyester, or combinations thereof. The oil can comprise a mineral
oil, such as a linear alkane, a branched alkane, or combinations
thereof. The oil can be selected from the group consisting of soy
bean oil, epoxidized soy bean oil, maleated soy bean oil, corn oil,
cottonseed oil, canola oil, castor oil, coconut oil, coconut seed
oil, corn germ oil, fish oil, linseed oil, olive oil, oiticica oil,
palm kernel oil, palm oil, palm seed oil, peanut oil, rapeseed oil,
safflower oil, sperm oil, sunflower seed oil, tall oil, tung oil,
whale oil, triolein, trilinolein, 1-stearo-dilinolein,
1-palmito-dilinolein, lauroleic acid, linoleic acid, linolenic
acid, myristoleic acid, oleic acid, palmitoleic acid,
1,2-diacetopalmitin, and combinations thereof. The oil can be
dispersed within the thermoplastic polymer such that the oil has a
droplet size of less than 10 .mu.m, less than 5 .mu.m, less than 1
.mu.m, or less than 500 nm within the thermoplastic polymer. The
oil can be a renewable material.
[0076] In one aspect, the present disclosure is directed to films
having at least one layer of a composition comprising an intimate
admixture of a thermoplastic starch (TPS), a thermoplastic polymer
and an oil, wax, or combination thereof present in an amount of
about 5 wt % to about 40 wt %, based upon the total weight of the
composition.
[0077] Some or all of the above detailed materials may also be
bio-degradable.
Exemplary Synthetic Polymers
[0078] Olefins derived from renewable resources may be polymerized
to yield polyolefins. Such polymers are typically referred to as
"bio-identical" polymers. Ethylene and propylene derived from
renewable resources may be polymerized under the appropriate
conditions to prepare polyethylene and/or polypropylene having
desired characteristics for use in consumer packages. The
polyethylene and/or polypropylene may be high density, medium
density, low density, or linear-low density. Further, polypropylene
can include homopolymer-polypropylene or co-polymer polypropylene.
Polyethylene and/or polypropylene may be produced via free-radical
polymerization techniques, or by using Ziegler-Natta (ZN) catalysis
or Metallocene catalysts. Examples of such bio-sourced
polyethylenes and polypropylenes are described in U.S. Publication
Nos. 2010/0069691, 2010/0069589, 2009/0326293, and 2008/0312485,
PCT Application Nos. WO2010063947 and WO2009098267; and European
Patent No. 1102569. Other olefins that can be derived from
renewable resources include butadiene and isoprene. Examples of
such olefins are described in U.S. Publication Nos. 2010/0216958
and 2010/0036173.
[0079] Such polyolefins being derived from renewable resources can
also be reacted to form various copolymers, including for example,
random block copolymers, such as ethylene-propylene random block
copolymers (e.g., Borpact.TM. BC918CF manufactured by Borealis).
Such copolymers and methods of forming the same are contemplated
and described for example in European Patent No. 2121318. In
addition, the polyolefin derived from a renewable resource may be
processed according to methods known in the art into a form
suitable for the end use of the polymer. The polyolefin may
comprise mixtures or blends with other polymers such as polyolefins
derived from petrochemicals.
[0080] Bio-polyethylene terephthalate is available from Teijin
Fibers Ltd. It also can be produced from the polymerization of
bio-ethylene glycol with bio-terephthalic acid. Bio-ethylene glycol
can be derived from renewable resources via a number of suitable
routes, such as, for example, those described in WO/2009/155086 and
U.S. Pat. No. 4,536,584, each incorporated herein by reference.
Bio-terephthalic acid can be derived from renewable alcohols
through renewable p-xylene, as described in WO/2009/079213, which
is incorporated herein by reference. In some embodiments, a
renewable alcohol (e.g., isobutanol) is dehydrated over an acidic
catalyst in a reactor to form isobutylene. The isobutylene is
recovered and reacted under the appropriate high heat and pressure
conditions in a second reactor containing a catalyst known to
aromatize aliphatic hydrocarbons to form renewable p-xylene. In
another embodiment, a renewable alcohol (e.g., isobutanol) is
dehydrated and dimerized over an acid catalyst. The resulting
diisobutylene is recovered and reacted in a second reactor to form
renewable p-xylene. In yet another embodiment, a renewable alcohol
(e.g., isobutanol) containing up to 15 wt. % water is dehydrated,
or dehydrated and oligomerized, and the resulting oligomers are
aromatized to form renewable p-xylene. Renewable phthalic acid or
phthalate esters can be produced by oxidizing p-xylene over a
transition metal catalyst (see, e.g., Ind. Eng. Chem. Res.,
39:3958-3997 (2000)), optionally in the presence of one or more
alcohols.
[0081] Bio-poly(ethylene-2,5-furandicarboxylate), a.k.a., bio-PEF,
can be produced according to the route disclosed in Werpy and
Petersen, "Top Value Added Chemicals from Biomass. Volume
I--Results of Screening for Potential Candidates from Sugars and
Synthesis Gas, produced by the Staff at Pacific Northwest National
Laboratory (PNNL): National Renewable Energy Laboratory (NREL),
Office of Biomass Program (EERE)," 2004 and PCT Application No. WO
2010/077133, which are both incorporated herein by reference.
[0082] It should be recognized that any of the aforementioned
synthetic polymers (e.g., copolymers) may be formed by using a
combination of monomers derived from renewable resources and
monomers derived from non-renewable (e.g., petroleum) resources.
For example, the copolymer can comprise propylene repeat units
derived from a renewable resource and isobutylene repeat units
derived from a petroleum source.
[0083] In addition to being formed from the synthetic polymers
described herein, the consumer packages can further include
additional additives. For example, opacifying agents can be added.
Such opacifying agents can include iron oxides, carbon black,
aluminum, aluminum oxide, titanium dioxide, talc and combinations
thereof. These opacifying agents can comprise about 0.1% to about
5% by weight of the packages; and in certain embodiments, the
opacifying agents can comprise about 0.3% to about 3% of the
packages. It will be appreciated that other suitable opacifying
agents may be employed and in various concentrations. Examples of
opacifying agents are described in U.S. Pat. No. 6,653,523.
[0084] Furthermore, the consumer packages may comprise other
additives, such as other polymers (e.g., a polypropylene, a
polyethylene, a ethylene vinyl acetate, a polyethylene
terephthalate, a polymethylpentene, any combination thereof, or the
like--whether derived from a renewable resource or petro-based
source), a filler (e.g., glass, talc, calcium carbonate, or the
like), a mold release agent, a flame retardant, an electrically
conductive agent, an anti-static agent, a pigment (inorganic or
organic), an antioxidant, an impact modifier, a stabilizer (e.g., a
UV absorber), wetting agents, dyes, or any combination thereof.
[0085] Some materials used in the structures described herein may
be a blend comprising a petro-based or renewable based
"bio-identical" polyolefin blend mixed with a renewable "bio-new"
material. Typically the "bio-new" material would be added to the
petro-based or renewable based "bio-identical" polyolefin in the
range 5-50 wt %, as higher than that would typically be difficult
to process. The blend could also contain some recycled materials,
typically up to around 50%--higher than that level could typically
cause gels to form in the film which act as imperfections.
Validation of Polymers Derived from Renewable Resources
[0086] A suitable validation technique is through .sup.14C
analysis. A small amount of the carbon dioxide in the atmosphere is
radioactive. .sup.14C carbon dioxide is created when nitrogen is
struck by an ultra-violet light produced neutron, causing the
nitrogen to lose a proton and form carbon of molecular weight 14
which is immediately oxidized to carbon dioxide. This radioactive
isotope represents a small but measurable fraction of atmospheric
carbon. Atmospheric carbon dioxide is cycled by green plants to
make organic molecules during photosynthesis. The cycle is
completed when the green plants or other forms of life metabolize
the organic molecules, thereby producing carbon dioxide which is
released back to the atmosphere. Virtually all forms of life on
Earth depend on this green plant production of organic molecules to
grow and reproduce. Therefore, the .sup.14C that exists in the
atmosphere becomes part of all life forms, and their biological
products. In contrast, fossil fuel based carbon does not have the
signature radiocarbon ratio of atmospheric carbon dioxide.
[0087] Assessment of the renewably based carbon in a material can
be performed through standard test methods. Using radiocarbon and
isotope ratio mass spectrometry analysis, the bio-based content of
materials can be determined. ASTM International, formally known as
the American Society for Testing and Materials, has established a
standard method for assessing the bio-based content of materials.
The ASTM method is designated ASTM D6866-10.
[0088] The application of ASTM D6866-10 to derive a "bio-based
content" is built on the same concepts as radiocarbon dating, but
without use of the age equations. The analysis is performed by
deriving a ratio of the amount of organic radiocarbon (.sup.14C) in
an unknown sample to that of a modern reference standard. The ratio
is reported as a percentage with the units "pMC" (percent modern
carbon).
[0089] The modern reference standard used in radiocarbon dating is
a NIST (National Institute of Standards and Technology) standard
with a known radiocarbon content equivalent approximately to the
year AD 1950. AD 1950 was chosen since it represented a time prior
to thermo-nuclear weapons testing which introduced large amounts of
excess radiocarbon into the atmosphere with each explosion (termed
"bomb carbon"). The AD 1950 reference represents 100 pMC.
[0090] "Bomb carbon" in the atmosphere reached almost twice normal
levels in 1963 at the peak of testing and prior to the treaty
halting the testing. Its distribution within the atmosphere has
been approximated since its appearance, showing values that are
greater than 100 pMC for plants and animals living since AD 1950.
It's gradually decreased over time with today's value being near
107.5 pMC. This means that a fresh biomass material such as corn
could give a radiocarbon signature near 107.5 pMC.
[0091] Combining fossil carbon with present day carbon into a
material will result in a dilution of the present day pMC content.
By presuming 107.5 pMC represents present day biomass materials and
0 pMC represents petroleum derivatives, the measured pMC value for
that material will reflect the proportions of the two component
types. A material derived 100% from present day soybeans would give
a radiocarbon signature near 107.5 pMC. If that material was
diluted with 50% petroleum derivatives, for example, it would give
a radiocarbon signature near 54 pMC (assuming the petroleum
derivatives have the same percentage of carbon as the
soybeans).
[0092] A biomass content result is derived by assigning 100% equal
to 107.5 pMC and 0% equal to 0 pMC. In this regard, a sample
measuring 99 pMC will give an equivalent bio-based content value of
92%.
[0093] Assessment of the materials described herein was done in
accordance with ASTM D6866. The mean values encompass an absolute
range of 6% (plus and minus 3% on either side of the bio-based
content value) to account for variations in end-component
radiocarbon signatures. It is presumed that all materials are
present day or fossil in origin and that the desired result is the
amount of bio-based component "present" in the material, not the
amount of bio-based material "used" in the manufacturing
process.
[0094] In one embodiment, a mono-layer film comprises a bio-based
content value from about 10% to about 100% using ASTM D6866-10,
method B. In another embodiment, a mono-layer film comprises a
bio-based content value from about 20% to about 100% using ASTM
D6866-10, method B. In yet another embodiment, a mono-layer film
comprises a bio-based content value from about 50% to about 100%
using ASTM D6866-10, method B.
[0095] In one embodiment, a multi-layer film comprises a bio-based
content value from about 10% to about 100% using ASTM D6866-10,
method B. In another embodiment, a multi-layer film comprises a
bio-based content value from about 20% to about 100% using ASTM
D6866-10, method B. In yet another embodiment, a multi-layer film
comprises a bio-based content value from about 50% to about 100%
using ASTM D6866-10, method B.
[0096] In order to apply the methodology of ASTM D6866-10 to
determine the bio-based content of a package, a representative
sample of the component must be obtained for testing. In one
embodiment, a representative portion of the package can be ground
into particulates less than about 20 mesh using known grinding
methods (e.g., Wiley.RTM. mill), and a representative sample of
suitable mass taken from the randomly mixed particles.
Other Materials
[0097] The consumer packages disclosed herein can optionally
include a colorant masterbatch. As used herein, a "colorant
masterbatch" refers to a mixture in which pigments are dispersed at
high concentration in a carrier material. The colorant masterbatch
is used to impart color to the final product. In some embodiments,
the carrier is a bio-based plastic or a petroleum-based plastic,
while in alternative embodiments, the carrier is a bio-based oil or
a petroleum-based oil. The colorant masterbatch can be derived
wholly or partly from a petroleum resource, wholly or partly from a
renewable resource, or wholly or partly from a recycled resource.
Non-limiting examples of the carrier include bio-derived or oil
derived polyethylene (e.g., linear low-density polyethylene
(LLDPE), low-density polyethylene (LDPE), high-density polyethylene
(HDPE)), bio-derived oil (e.g., olive oil, rapeseed oil, peanut
oil, soybean oil, or hydrogenated plant-derived oils),
petroleum-derived oil, recycled oil, bio-derived or petroleum
derived polyethylene terephthalate, polypropylene, and a mixture
thereof. The pigment of the carrier, which can be derived from
either a renewable resource or a non-renewable resource, can
include, for example, an inorganic pigment, an organic pigment, a
polymeric resin, or a mixture thereof. Non-limiting examples of
pigments include titanium dioxide (e.g., rutile, anatase), copper
phthalocyanine, antimony oxide, zinc oxide, calcium carbonate,
fumed silica, phthalocyamine (e.g., phthalocyamine blue),
ultramarine blue, cobalt blue, monoazo pigments, diazo pigments,
acid dye, base dye, quinacridone, and a mixture thereof. In some
embodiments, the colorant masterbatch can further include one or
more additives, which can either be derived from a renewable
resource or a non-renewable resource. Nonlimiting examples of
additives include slip agents, UV absorbers, nucleating agents, UV
stabilizers, heat stabilizers, clarifying agents, fillers,
brighteners, process aids, perfumes, flavors, and a mixture
thereof.
[0098] In some embodiments, color can be imparted to the films of
the present invention in any of the aspects by using direct
compounding (i.e., in-line compounding). In these embodiments, a
twin screw compounder is placed at the beginning of the injection
molding, blow molding, or film line and additives, such as
pigments, are blended into the resin just before article
formation.
[0099] Additional materials may be incorporated into the packages
of the present invention in any of the aspects to improve the
strength or other physical characteristics of the plastic. Such
additional materials include an inorganic salt, such as calcium
carbonate, calcium sulfate, tales, clays (e.g., nanoclays),
aluminum hydroxide, CaSiO3, glass fibers, glass spheres,
crystalline silicas (e.g., quartz, novacite, crystallobite),
magnesium hydroxide, mica, sodium sulfate, lithopone, magnesium
carbonate, iron oxide, or a mixture thereof.
[0100] In some alternative embodiments to any of the embodiments
described herein, elements of the package, including the sealant,
barrier material, tie layers, or mixtures thereof, include recycled
material in place of, or in addition to, the bio-based material in
an amount of up to 100% of the bio-based material. As used herein,
"recycled" materials encompass post-consumer recycled (PCR)
materials, post-industrial recycled (PIR) materials, and a mixture
thereof.
[0101] In some embodiments, the structure described above may
incorporate a barrier layer. The barrier material is selected from
the group consisting of aluminum, metallized polyolefin substrate,
metallized polyethylene terephthalate substrate, metallised
cellulose. PVDC, PCTFE, sol-gel coating. Instead of a metallized
coating on polyolefins or polyethylene terephthalate, the following
coatings could be used--metal oxide, a nanoclay, an aluminum oxide,
a silicon oxide, diamond-like carbon (DLC), and mixtures thereof.
Other barrier substrates (used with or without a coating) could
include EVOH, PVOH, Nylon, PVC, liquid crystal polymer. The
substrates could include within their structure, an additional
barrier additive (not in coating form but embedded within the
polymer matrix)--one example of such additives could include
nanoclays). The total barrier layer including the substrate
typically has a thickness of about 6 [mu]m to about 200 [mu]m.
Typically the substrate underneath the coating is cast biaxially
oriented, although it could be a blown or cast film too. In some
preferred embodiments, the metal is vacuum metallized aluminum. In
some embodiments when the barrier material is a nanoclay, the
nanoclay is selected from the group consisting of montmorillonites,
vermiculite platelets, and mixtures thereof.
[0102] In embodiments of the consumer packages described herein,
the ink that is deposited can be either solvent-based or
water-based. In some embodiments, the ink is high abrasive
resistant. For example, the high abrasive resistant ink can include
coatings cured by ultraviolet radiation (UV) or electron beams
(EB). In some embodiments, the ink is derived from a petroleum
source. In some embodiments, the ink is derived from a renewable
resource, such as soy, a plant, or a mixture thereof. Non-limiting
examples of inks include ECO-SURE!.TM. from Gans Ink & Supply
Co. and the solvent-based VUTEk.RTM. and BioVu.TM. inks from EFI,
which are derived completely from renewable resources (e.g., corn).
The ink is present in a thickness of about 0.5 [mu]m to about 20
[mu]m, preferably about 1 [mu]m to about 10 [mu]m, more preferably
about 2.5 [mu]m to about 3.5 [mu]m.
[0103] In embodiments of the consumer packages described herein, an
optional lacquer functions to protect the ink layer from its
physical and chemical environment, when reverse printing has not
been used. In some embodiments, the lacquer is selected from the
group consisting of resin, additive, and solvent/water. In some
preferred embodiments, the lacquer is nitrocellulose-based lacquer.
The lacquer is formulated to optimize durability and provide a
glossy or matte finish. The lacquer is present in a thickness of up
to about 25 [mu]m, preferably up to about 5 [mu]m.
[0104] Non-limiting examples of the adhesive can include acrylic,
polyvinyl acetate, and other commonly used adhesive tie layers
suitable for polar materials. In some embodiments, the adhesive is
a renewable adhesive, such as BioTAK.RTM. by Berkshire Labels.
[0105] In some embodiments, particular material combinations that
enable the film structure to be biodegradable or degradable may be
selected.
[0106] In some embodiments, the consumer packages described herein
are substantially free of oxo-biodegradable additives (i.e., less
than about 1 wt. %, based on the total weight of the package or
article) but in some embodiments oxo-biodegradable additives may be
used. Oxo-biodegradable additives consist of transition metals that
theoretically foster oxidation and chain scission in plastics when
exposed to heat, air, light, or a mixture thereof. Although the
shortened polymer chains theoretically can be consumed by
microorganisms found in the disposal environment and used as a food
source, there is no data to support how long these plastic
fragments will persist in the soils or marine environments, or if
biodegradation of these fragments occurs at all. However, in some
specific material blends, such materials may enable faster
biodegradation.
[0107] In addition embodiments where a biodegradable package is
desired, certain additives may be added to tune the degradability
of polymers to meet a specific degradability. For example, numerous
additives are known to tune the degradation of polymers with or
without being triggered by some external stimulus (e.g., exposure
to light) as disclosed in US 2010/0222454 A1, US 2004/0010051 A1,
US2009/0286060 A1 and references therein. Additionally, the article
"Photodegradation, Photooxidation, and Photostabilization of
Polymers," by Ranby and Rabek describe photodegradant materials.
While not wishing to be bound by theory, one example of these
additives (photo acid or photobase generators) tune the local pH in
response to exposure to certain wavelengths of light, which results
in hydrolysis of a polyester. Once these polymers are hydrolyzed to
a lower molecular weight, they are truly biodegraded by
microorganisms.
Opacity
[0108] As discussed above, the opacity of plastic films is adjusted
using whitening additives to achieve a desired appearance and
protection against light. While many methods can be used to
determine the opacity of a plastic film, two exemplary test methods
are described in ASTM 2805 and ISO 2471. Opacity is generally
expressed in terms of a percentage of light that is absorbed by the
film. For opaque LDPE thin films used in packaging, an opacity
value of from about 35% to about 99% is usually acceptable.
[0109] Typically, a reduction in film caliper results in a loss of
opacity, which requires an increase in whitening additives such as
titanium dioxide, or other coloring additives. Thus, it would seem
that the substitution of a foamed thin film for a non-foamed thin
film would likewise require an increased amount of whitening or
coloring additives to compensate for the reduction in the amount of
resin that is present in the foamed thin film. In addition, the
presence of voids in the foamed thin film would seem to further
reduce the opacity of the foamed thin film as compared to a
non-foamed film counterpart.
[0110] It has been discovered that the reduction in opacity of a
foamed thin film (e.g., mono film 10 in FIG. 1b) as compared to its
non-foamed thin film counterpart (e.g., mono film 100 in FIG. 1a)
is not proportional with respect to the reduction in resin weight.
In other words, the opacity of the foamed thin film (e.g., mono
film 10) is only slightly lower than the opacity of the non-foamed
thin film counterpart (e.g., mono film 100) even when a significant
amount of the resin has been removed due to foaming. The
degradation in opacity is much less than would be expected based on
the reduction in resin weight. This may be due to light reflecting
back at many angles as it encounters the curved inner surfaces of
the voids left by bubbles. As such, in many instances it is not
necessary to make any adjustments to the amount of whitening or
coloring additives used to achieve a desired opacity when using a
foamed thin film in place of a non-foamed film of substantially the
same caliper and composition. However, in the case where bio-new
materials are used to make the foamed films (especially bio-new
materials blended into a petro-based material such as
polyethylene), we see yet even higher increase in opacity, due to
the typical incompatibility with the polyolefin matrix, which
causes an increase in the reflectivity of light impinging on the
sample.
[0111] As can be seen by the foregoing description, the use of
foamed thin films in consumer packaging applications that include
opening features allows for resin savings and, surprisingly, the
methods of producing the opening features as well as the
configuration of the opening features remains substantially the
same as with non-foamed thin films of substantially the same
caliper. In addition, foamed thin films provide substantially
similar levels of opacity to their non-foamed thin film
counterparts. These discoveries allow for a new and ready use of
foamed thin films for non-foamed thin films in packages with
opening features and/or a need for a level of opacity.
[0112] The dimensions and values disclosed herein are not to be
understood as being strictly limited to the exact numerical values
recited. Instead, unless otherwise specified, each such dimension
is intended to mean both the recited value and a functionally
equivalent range surrounding that value. For example, a dimension
disclosed as "40 mm" is intended to mean "about 40 mm".
[0113] Every document cited herein, including any cross referenced
or related patent or application, is hereby incorporated herein by
reference in its entirety unless expressly excluded or otherwise
limited. The citation of any document is not an admission that it
is prior art with respect to any invention disclosed or claimed
herein or that it alone, or in any combination with any other
reference or references, teaches, suggests or discloses any such
invention. Further, to the extent that any meaning or definition of
a term in this document conflicts with any meaning or definition of
the same term in a document incorporated by reference, the meaning
or definition assigned to that term in this document shall
govern.
[0114] While particular embodiments of the present invention have
been illustrated and described, it would be obvious to those
skilled in the art that various other changes and modifications can
be made without departing from the spirit and scope of the
invention. It is therefore intended to cover in the appended claims
all such changes and modifications that are within the scope of
this invention.
* * * * *