U.S. patent application number 13/648453 was filed with the patent office on 2013-04-18 for oxygen-scavenging materials and articles formed therefrom.
This patent application is currently assigned to Valspar Sourcing, Inc.. The applicant listed for this patent is Valspar Sourcing, Inc.. Invention is credited to Richard Evans, Jeffrey Niederst, Grant Schutte, Paul Share.
Application Number | 20130095334 13/648453 |
Document ID | / |
Family ID | 42100869 |
Filed Date | 2013-04-18 |
United States Patent
Application |
20130095334 |
Kind Code |
A1 |
Share; Paul ; et
al. |
April 18, 2013 |
Oxygen-Scavenging Materials and Articles Formed Therefrom
Abstract
An oxygen-scavenging composition is provided that includes an
oxygen-scavenging component and a catalyst. The oxygen-scavenging
component, which in preferred embodiments is suitable for use in
packaging articles, includes two or more oxygen-scavenging groups
having different scavenging properties. In one embodiment, one of
the oxygen-scavenging groups is an unsaturated bicyclic group.
Inventors: |
Share; Paul; (Wexford,
PA) ; Niederst; Jeffrey; (Leechburg, PA) ;
Evans; Richard; (Wexford, PA) ; Schutte; Grant;
(Pittsburgh, PA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Valspar Sourcing, Inc.; |
Minneapolis |
MN |
US |
|
|
Assignee: |
Valspar Sourcing, Inc.
Minneapolis
MN
|
Family ID: |
42100869 |
Appl. No.: |
13/648453 |
Filed: |
October 10, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13123396 |
May 16, 2011 |
8308976 |
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PCT/US2008/079618 |
Oct 10, 2008 |
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13648453 |
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Current U.S.
Class: |
428/474.7 ;
252/188.28 |
Current CPC
Class: |
B32B 27/08 20130101;
B32B 27/38 20130101; B32B 2439/80 20130101; B32B 27/18 20130101;
B32B 27/322 20130101; B32B 27/36 20130101; B32B 27/283 20130101;
B32B 2439/70 20130101; Y10T 428/31728 20150401; B32B 27/308
20130101; B32B 27/40 20130101; B32B 2307/50 20130101; B32B 27/34
20130101; B32B 27/285 20130101; B32B 27/281 20130101; B32B 27/286
20130101; B32B 27/304 20130101; B32B 27/32 20130101; B32B 27/302
20130101; B32B 2553/00 20130101; B32B 27/288 20130101; C09K 15/22
20130101; B32B 27/365 20130101; B32B 2307/7244 20130101; B32B
2270/00 20130101 |
Class at
Publication: |
428/474.7 ;
252/188.28 |
International
Class: |
C09K 15/22 20060101
C09K015/22 |
Claims
1. A composition comprising: an oxygen-scavenging component
including: a polyamide oxygen-scavenging group, and a bicyclic
oxygen-scavenging group having at least one double bond located
between atoms of a ring, wherein at least one of the polyamide or
bicyclic oxygen-scavenging groups is included in a polymer; and an
oxidation catalyst.
2. The composition of claim 1, wherein the polyamide
oxygen-scavenging group and the bicyclic oxygen-scavenging group
are present on different polymers.
3. The composition of claim 1, wherein the bicyclic group comprises
a structure represented by the nomenclature expression:
bicyclo[x,y,z]alkene; wherein: x is 2 or more, and y and z are each
at least 1.
4. The composition of claim 3, wherein: x is 2 or 3, and y and z
are independently 1 or 2.
5. The composition of claim 1, wherein the bicyclic group comprises
bicyclo[2.1.1]hexene, bicyclo[2.2.1]heptene,
bicyclo[2.2.1]heptadiene, bicyclo[2.2.2]octene,
bicyclo[2.2.2]octadiene, or a mixture thereof.
6. The composition of claim 1, wherein the bicyclic group is
included in a polymer having a condensation backbone.
7. The composition of claim 6, wherein the condensation backbone
comprises a polyester, copolyester, polyamide, polycarbonate,
polyether, polyurethane, polyepoxide, polylactone, a derivative or
copolymer thereof, or a mixture thereof.
8. The composition of claim 6, wherein the polymer including the
bicyclic group comprises a polyester polymer.
9. The composition of claim 6, wherein the bicyclic group comprises
a pendant group attached to the condensation backbone.
10. The composition of claim 9, wherein the pendant group is a
reaction product of ingredients including an unsaturated fatty
acid.
11. The composition of claim 1, wherein the polyamide group
comprises a structural unit represented by the below structural
formula (I): -arylene-C(HR.sup.1)--N(R.sup.2)--(C.dbd.O)--, wherein
R.sup.1 and R.sup.2 independently denote one of a hydrogen atom, a
substituted or unsubstituted alkyl group, a substituted or
unsubstituted cycloalkyl group, a substituted or unsubstituted aryl
group, or a substituted or unsubstituted alkenyl or cycloalkenyl
group.
12. The composition of claim 1, wherein the composition comprises
at least about 25 parts per million of the oxidation catalyst.
13. The composition of claim 12, wherein the oxidation catalyst
comprises one or more transition metals, transition metal
complexes, or mixtures thereof.
14. The composition of claim 1, wherein the oxidation catalyst
comprises a cobalt catalyst.
15. A packaging article, comprising the composition of claim 1.
16. The packaging article of claim 15, wherein the article
comprises a single-layer packaging article.
17. The packaging article of claim 15, wherein the packaging
article comprises a multi-layer packaging article.
18. The packaging article of claim 15, wherein the article
comprises about 15 wt-% or less of the oxygen-scavenging
component.
19. A method, comprising: providing: a conjugated diene component,
and an unsaturated component; and forming a first oxygen-scavenging
polymer that includes a bicyclic group that is a Diels-Alder
reaction product of the above components, wherein the bicyclic
group includes at least one ring having a double bond located
between atoms of the ring; and forming an oxygen-scavenging
composition that comprises: (i) the first oxygen-scavenging
polymer; (ii) at least one of: (a) a structural unit represented by
the below structural formula (I):
-arylene-C(HR.sup.1)--N(R.sup.2)--(C.dbd.O)--, wherein R.sup.1 and
R.sup.2 independently denote one of a hydrogen atom, a substituted
or unsubstituted alkyl group, a substituted or unsubstituted
cycloalkyl group, a substituted or unsubstituted aryl group, or a
substituted or unsubstituted alkenyl or cycloalkenyl group; or (b)
an unsaturated oxygen-scavenging group that includes at least one
carbon-carbon double bond with a heat of hydrogenation of less than
or equal to that of cyclohexene; wherein the above (a) or (b) are
present on the first oxygen-scavenging polymer or a second
oxygen-scavenging polymer; and (iii) an oxidation catalyst.
20. A composition comprising: an oxygen-scavenging component having
at least one of: a first oxygen-scavenging comprising a cyclic or
bicyclic oxygen-scavenging group having at least one carbon-carbon
double bond located between atoms of a ring, wherein: the
carbon-carbon double bond has a heat of hydrogenation of at least
33 kcal/mole, and the cyclic or bicyclic group is included in a
polymer having a condensation backbone; and a second
oxygen-scavenging group comprising: one or more of a structural
unit represented by the formula:
-arylene-C(HR.sup.1)--N(R.sup.2)--(C.dbd.O)--, wherein R.sup.1 and
R.sup.2 independently denote one of a hydrogen atom, a substituted
or unsubstituted alkyl group, a substituted or unsubstituted
cycloalkyl group, a substituted or unsubstituted aryl group, or a
substituted or unsubstituted alkenyl or cycloalkenyl group, or an
unsaturated oxygen-scavenging group that includes at least one
carbon-carbon double bond with a heat of hydrogenation of 32
kcal/mole or less; and an oxidation catalyst.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application includes subject matter that may be related
to International Application No. PCT/US08/59562 by Share et al. and
International Application No. ______ by Share et al. entitled
OXYGEN-SCAVENGING COMPOSITION AND ARTICLE FORMED THEREFROM
(attorney docket no. 06-1959-0201) and filed on even date herewith,
each of which are incorporated herein by reference in their
entirety.
TECHNICAL FIELD
[0002] This invention relates to oxygen-scavenging materials and
articles formed therefrom.
BACKGROUND
[0003] Historically, oxygen-sensitive products have been packaged
and shipped in either glass or metal containers for delivery to the
consumer. These containers have essentially zero gas permeability
and, as such, the oxygen-sensitive products are able to remain
fresh for an extended period of time.
[0004] There is a growing desire to package certain products such
as, for example, foods and beverage products, in various plastic
(e.g., PET, HDPE, PP, etc.) containers, wrapping, and other
packaging articles. Compared to glass or metal packaging, plastic
packaging is typically cheaper, more resistant to breakage, and
more flexible (if desired). Conventional plastics, however, have
generally functioned poorly at blocking oxygen passage relative to
other available materials, such as glass or metal. The permeability
of conventional plastics to oxygen transmission can result in short
product shelf life, especially for products that are sensitive to
degradation when exposed to oxygen.
[0005] Oxygen-scavenging materials have been incorporated into
plastic containers in an attempt to maintain a low level of oxygen
within the container, thereby extending the shelf life of the
product. These plastic containers, however, have typically suffered
from one or more deficiencies such as loss of adhesion,
delamination, presence of off tastes or odors in products packaged
therein, poor clarity, cost (e.g., material, storage, and/or
transportation costs), insufficient oxygen-scavenging capacity
and/or shelf life, and inefficient or untimely activation of oxygen
scavenging.
[0006] Thus, there is a continuing need for improved
oxygen-scavenging materials for use in packaging articles.
SUMMARY
[0007] In one aspect, the invention is an oxygen-scavenging
composition suitable for use in a variety of applications
including, for example, in packaging articles. In some embodiments,
the oxygen-scavenging composition includes a "fast" OS group such
as, for example, an oxygen-scavenging component (preferably
including at least one oxygen-scavenging polymer) which includes a
bicyclic oxygen-scavenging group preferably having at least one
double bond located between atoms of a ring. The oxygen-scavenging
component preferably further includes one or more additional
oxygen-scavenging groups that preferably have a scavenging property
different from that of the aforementioned bicyclic group. In one
embodiment, the one or more additional oxygen-scavenging groups
comprise (i) a polyamide group, (ii) an unsaturated group, (e.g., a
cyclohexene group) that includes at least one carbon-carbon double
bond preferably having a heat of hydrogenation of less than about
32 kcal/mole, or (iii) a mixture thereof.
[0008] In some embodiments, the oxygen-scavenging component
includes a first oxygen-scavenging group and a second
oxygen-scavenging group, wherein the first oxygen-scavenging
preferably comprises a cyclic or bicyclic oxygen-scavenging group
having at least one carbon-carbon double bond located between atoms
of a ring. The carbon-carbon double bond of the unsaturated cyclic
or bicyclic group preferably has a heat of hydrogenation of at
least 33 kcal/mole. The cyclic or bicyclic group is preferably
included in a polymer, more preferably a polymer having a
condensation backbone such as, for example, a polyester backbone.
The second oxygen-scavenging group preferably comprises a group
selected from (i) a structural unit represented by the formula
-arylene-C(HR.sup.1)--N(R.sup.2)--(C.dbd.O)--, wherein R.sup.1 and
R.sup.2 preferably independently denote one of a hydrogen atom, a
substituted or unsubstituted alkyl group, a substituted or
unsubstituted cycloalkyl group, a substituted or unsubstituted aryl
group, or a substituted or unsubstituted alkenyl or cycloalkenyl
group, or (ii) an unsaturated oxygen-scavenging group that includes
at least one carbon-carbon double bond with a heat of hydrogenation
of 32 kcal/mole or less.
[0009] In another aspect, the invention provides methods for making
the oxygen-scavenging composition described herein. In one
embodiment, a Diels-Alder reaction is used to form a bicyclic
oxygen-scavenging group included in the oxygen-scavenging component
of the composition.
[0010] In another aspect, the invention provides articles that
include oxygen-scavenging compositions described herein. In some
embodiments, the articles comprise monolayer or multilayer
packaging articles.
[0011] The above summary of the invention is not intended to
describe each disclosed embodiment or every implementation of the
invention. The description that follows more particularly
exemplifies illustrative embodiments. In several places throughout
the application, guidance is provided through lists of examples,
which can be used in various combinations. In each instance, the
recited list serves only as a representative group and should not
be interpreted as an exclusive list.
[0012] The details of one or more embodiments of the invention are
set forth in the description below. Other features, objects, and
advantages of the invention will be apparent from the description
and drawings and the claims.
DEFINITIONS
[0013] Unless otherwise specified, the following terms as used
herein have the meanings provided below.
[0014] The term "organic group" means a hydrocarbon group (with
optional elements other than carbon and hydrogen, such as oxygen,
nitrogen, sulfur, and silicon) that is classified as an acyclic
group, cyclic group, or combination of acyclic and cyclic groups
(e.g., alkaryl and aralkyl groups). The term "acyclic group" means
a saturated or unsaturated linear or branched hydrocarbon group.
This term is used to encompass alkyl, alkenyl, and alkynyl groups,
for example. The term "alkyl group" means a saturated linear or
branched hydrocarbon group including, for example, methyl, ethyl,
isopropyl, t-butyl, heptyl, dodecyl, octadecyl, amyl, 2-ethylhexyl,
and the like. The term "alkenyl group" means an unsaturated, linear
or branched hydrocarbon group with one or more carbon-carbon double
bonds, such as a vinyl group. The term "alkynyl group" means an
unsaturated, linear or branched hydrocarbon group with one or more
carbon-carbon triple bonds. The term "cyclic group" refers to a
group that contains one or more closed ring hydrocarbon groups,
which can include heteroatoms and/or one or more pendant groups,
including, e.g., ring and/or non-ring (e.g., acyclic) pendant
groups. The term includes any type of substituted or unsubstituted
ring hydrocarbon group, including, for example, bicyclic groups and
fused ring groups. The term "bicyclic group" refers to a group that
includes at least two closed ring hydrocarbon groups, which can
include heteroatoms, that share at least two bonds and three atoms.
Nobomene (also referred to as bicyclo[2.2.1]heptene) is an example
of a bicyclic group. The term "fused ring group" refers to a closed
ring hydrocarbon group, which can include heteroatoms, that
includes at least two rings that share one bond and two atoms.
Napthalene is an example of a fused ring group.
[0015] A group that may be the same or different is referred to as
being "independently" something. Substitution is anticipated on the
organic groups of the compounds of the invention. As a means of
simplifying the discussion and recitation of certain terminology
used throughout this application, the terms "group" and "moiety"
are used to differentiate between chemical species that allow for
substitution or that may be substituted and those that do not allow
or may not be so substituted. Thus, when the term "group" is used
to describe a chemical substituent, the described chemical material
includes the unsubstituted group and that group with O, N, Si, or S
atoms, for example, in the chain (as in an alkoxy group) as well as
carbonyl groups or other conventional substitution. Where the term
"moiety" is used to describe a chemical compound or substituent,
only an unsubstituted chemical material is intended to be included.
For example, the phrase "alkyl group" is intended to include not
only pure open chain saturated hydrocarbon alkyl substituents, such
as methyl, ethyl, propyl, t-butyl, and the like, but also alkyl
substituents bearing further substituents known in the art, such as
hydroxy, alkoxy, alkylsulfonyl, halogen atoms, cyano, nitro, amino,
carboxyl, etc. Thus, "alkyl group" includes ether groups,
haloalkyls, nitroalkyls, carboxyalkyls, hydroxyalkyls, sulfoalkyls,
etc. On the other hand, the phrase "alkyl moiety" is limited to the
inclusion of only pure open chain saturated hydrocarbon alkyl
substituents, such as methyl, ethyl, propyl, t-butyl, and the like.
The disclosure of a particular group herein is intended to be an
explicit disclosure of both the group and the corresponding moiety.
Thus, disclosure of an "alkyl group" is also explicit disclosure of
the "alkyl moiety" included therein.
[0016] The term "component" refers to any compound that includes a
particular feature or structure. Examples of components include
compounds, monomers, oligomers, polymers, and organic groups
contained therein.
[0017] The term "double bond" is non-limiting and refers to any
type of double bond between any suitable atoms (e.g., C, O, N,
etc.).
[0018] The term "triple bond" is non-limiting and refers to any
type of triple bond between any suitable atoms.
[0019] The term "conjugated diene component" refers to a component
that includes at least two conjugated double bonds, each of which
can be any type of double bond. Thus, for example, a component that
includes a --CH.dbd.CH--CH.dbd.CH--CH.dbd.CH-- structure
constitutes a conjugated diene component even though it includes 3
or more double bonds.
[0020] The term "cyclic conjugated diene component" refers to a
conjugated diene component having at least one ring that includes
at least one conjugated double bond located therein. The one or
more other conjugated double bonds, for example, may also be
located on the ring and/or may be located in a group attached to
the ring.
[0021] The term "unsaturated component" refers to a component that
includes at least one double bond or triple bond.
[0022] The term "cyclopentadiene" includes both cyclopentadiene and
dicyclopentadiene.
[0023] The term "cyclopentadiene component" refers to a component
that contains a substituted or unsubstituted cyclopentadiene group,
and encompasses both cyclopentadiene and dicyclopentadiene.
[0024] The term "thermoplastic" refers to a material that melts and
changes shape when sufficiently heated and hardens when
sufficiently cooled. Such materials are typically capable of
undergoing repeated melting and hardening without exhibiting
appreciable chemical change. In contrast, a "thermoset" refers to a
material that is crosslinked and does not "melt."
[0025] The term "food-contact surface" refers to a surface of an
article (e.g., a food or beverage container) that is in contact
with, or suitable for contact with, a food or beverage product.
[0026] The term "comprises" and variations thereof do not have a
limiting meaning where these terms appear in the description and
claims.
[0027] The term "oxygen scavenging" means absorbing, consuming, or
reducing the amount of oxygen from a given environment.
[0028] The term "packaging article" as used herein includes both
packaging articles in their final commercial form, as well as any
intermediate stages. Preforms, which are frequently formed for
plastic containers and other packaging articles, are one example of
such an intermediate stage. The term includes at least films,
bottles, containers, closures, closure liners, etc.
[0029] The terms "preferred" and "preferably" refer to embodiments
of the invention that may afford certain benefits, under certain
circumstances. However, other embodiments may also be preferred
under the same, or other circumstances. Furthermore, the recitation
of one or more preferred embodiments does not imply that other
embodiments are not useful, and is not intended to exclude other
embodiments from the scope of the invention.
[0030] As used herein, "a," "an," "the," "at least one," and "one
or more" are used interchangeably. Thus, for example, a coating
composition that comprises "an" additive can be interpreted to mean
that the coating composition includes "one or more" additives.
[0031] Also herein, the recitations of numerical ranges by
endpoints include all numbers subsumed within that range (e.g., 1
to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.). Furthermore,
disclosure of a range includes disclosure of all subranges included
within the broader range (e.g., 1 to 5 discloses 1 to 4, 1.5 to
4.5, 1 to 2, etc.).
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] FIG. 1 is a graph which shows the concentration of oxygen
(over time) present in (i) a sealed PET beverage bottle having a
monolayer sidewall containing about 1 weight percent (wt-%) MXD6
nylon and 12 ppm cobalt neodecanoate (corresponds to "Scavenger"
plot) relative to that of (ii) a sealed control PET beverage bottle
having no scavenger materials (corresponds to "PET" plot).
DETAILED DESCRIPTION
[0033] The invention provides an oxygen-scavenging composition ("OS
composition") that preferably includes two or more
oxygen-scavenging groups ("OS Groups") and/or materials that
exhibit one or more different oxygen-scavenging properties. The
invention further provides coating compositions and articles,
including, for example, articles for packaging oxygen-sensitive
products, which include one or more layers of the oxygen-scavenging
composition of the invention. Examples of such packaging articles
may include flexible or rigid articles for packaging
oxygen-sensitive products such as oxygen-sensitive food or beverage
products, medical products, computer parts, electrical parts, or
other materials sensitive to oxygen. It is further contemplated
that OS compositions of the invention may be used in non-packaging
applications where oxygen-scavenging properties are desired.
[0034] MXD6 nylon (from Mitsubishi), in combination with an
oxidation catalyst, is a common oxygen-scavenging material for use
in packaging articles. We have observed that packaging articles
containing MXD6 nylon, which has not been pre-activated (i.e.,
activated prior to product packaging, e.g., during manufacture
and/or storage of a packaging article), tends to exhibit a "slow"
initial rate of oxygen scavenging upon product packaging relative
to the rate of oxygen-scavenging exhibited after activation has
been fully achieved. Once activation has been fully achieved, MXD6
nylon typically exhibits a robust and stable oxygen-scavenging
capability for an extended period of time. The comparatively "slow"
initial rate of oxygen-scavenging for MXD6 nylon, however, may be
potentially problematic for products that are especially sensitive
to oxygen. Other conventional OS materials may also suffer from
similar drawbacks prior to the oxygen-scavenging properties of the
materials being fully activated. For example, certain polymers
containing pendant cyclohexene groups (e.g., such as described by
Ching et al. in WO 99/48963, assigned to Chevron) or related
C.sub.5-C.sub.9 unsaturated cycloaliphatic groups may exhibit a
comparatively low level of initial oxygen-scavenging upon product
packaging (assuming a potentially costly aging step was not
utilized prior to product packaging). For purposes of convenience,
such oxygen-scavenging groups and/or materials will be collectively
referred to herein as "slow" oxygen-scavenging materials.
[0035] The potential affects of a "slow" initial rate of scavenging
are illustrated graphically in FIG. 1, which shows the
concentration of oxygen (over time) present in a sealed PET
beverage bottle having a monolayer sidewall containing about 1
weight percent (wt-%) MXD6 nylon and about 12 ppm cobalt
neodecanoate. The MXD6 nylon present in the bottle was not
purposefully activated prior to product filling. At day 0, the
bottle was filled with aqueous product and sealed. As depicted in
FIG. 1, the sealed bottle contained an initial amount of entrapped
oxygen, which is typical for sealed packaging articles due to the
presence of oxygen dissolved within the packaged product and/or
present in any headspace gas. As seen in FIG. 1, the amount of
entrapped oxygen initially increased between days 0 and 160. This
increase is believed to be due to the initial scavenging rate of
the MXD6 nylon being less than the rate of oxygen ingress. While
not intending to be bound by a theory, in addition to scavenger
content, the scavenging "lag" illustrated in FIG. 1 may be
dependent on the specifics of package design such as layer
thickness, surface to volume ratio, and headspace volume and
composition. For a given package design, the content of MXD6 nylon
and cobalt catalyst in the barrier layer may be substantially
increased to a level at which little, or no, measurable lag is
present; however, such packaging articles may suffer from a variety
of drawbacks including, for example, increased cost and/or
increased haze or layer separation.
[0036] Materials and/or packaging articles with oxygen-scavenging
profiles such as that of FIG. 1 may not be ideal for certain
applications. For example, for products that are especially
sensitive to oxygen-mediated degradation, it may desirable to pack
the products in a packaging article having a suitably high amount
of initial scavenging to rapidly scavenge any oxygen present in the
product and/or headspace and thereby avoid degradation of the
product via entrapped oxygen.
[0037] The use of an OS composition with a single type of OS group
may also have one or more drawbacks. For example, such a material
may have a robust initial ability to scavenge oxygen upon product
packaging, but may not have the capacity and/or shelf-life to
provide suitable levels of oxygen-scavenging over extended periods
of time (e.g., months, years, etc.). This may result in
degradation, via oxygen ingress, of packaged products having long
commercial shelf-lives.
[0038] Rather than employing a single type of OS group, we have
found that certain end use applications may benefit from a "hybrid"
approach that uses two or more OS groups having different
oxygen-scavenging properties and, more preferably, different
oxygen-scavenging kinetics. The two or more different OS groups may
be included in (i) a single polymer, (ii) separate polymers, or
(iii) a mixture thereof. Alternatively, one or more of the OS
groups may be included in one or more non-polymer OS components
(e.g., monomers or oligomers including one or more OS groups). By
selecting particular types and quantities of OS groups, an article
may be produced that exhibits an oxygen-scavenging property (e.g.,
an oxygen-scavenging profile) that may not otherwise be achievable
through use of a single type of OS group. For example, to achieve
unique oxygen-scavenging profiles, preferred OS compositions of the
invention include at least a first and a second OS group that
preferably differ in one or more of the following properties: the
mechanism for initiating oxygen-scavenging; scavenging kinetics;
the induction period (i.e., the delay, if any, between packaging of
an oxygen-sensitive product and the onset of appreciable
oxygen-scavenging); the rate of oxygen-scavenging; and the time
period for which the OS groups remains active and capable of
scavenging oxygen (i.e., days, weeks, months, years, etc.).
[0039] In some embodiments of the invention, an OS composition is
provided that exhibits both (i) robust initial oxygen scavenging
(e.g., upon packaging of product) attributable, at least in part,
to a first OS group and (ii) long-lasting oxygen scavenging (e.g.,
weeks, months, or years) attributable, at least in part, to a
second OS group. By including a first OS group having a robust
initial oxygen-scavenging response, the initial entrapped oxygen
can be scavenged prior to the occurrence of any appreciable
degradation of the packaged product.
[0040] We have discovered that unsaturated bicyclic OS groups can
provide a robust initial oxygen-scavenging response. Moreover, we
have discovered that the inclusion of a suitable amount of bicyclic
OS groups in an OS composition containing a "slow"
oxygen-scavenging material such as, for example, MXD6 nylon can
prevent the persistence and/or accumulation of entrapped oxygen
within a sealed packaging article during the time period following
product packaging. Thus, in presently preferred embodiments, the OS
composition of the invention includes an oxygen-scavenging
component ("OS component") including: (i) a first OS group in the
form of an unsaturated bicyclic group preferably having one or more
double bonds in a ring of the bicyclic group and (ii) a second OS
group having one or more oxygen-scavenging properties different
from that of the bicyclic group. In presently preferred
embodiments, the second OS group is (a) a polyamide OS group and/or
(b) an acyclic or cyclic OS group having a carbon-carbon double
bond. More preferably, the second OS group is a polyamide group
such as a benzylic amide or benzylic polyamide group. The term
"polyamide group" as used herein is intended to encompass both
amide groups and polyamide OS groups.
[0041] The OS component may constitute a single polymer or a
mixture of different polymers. For example, the OS component may
include a polymer having both one or more bicyclic OS groups and
one or more polyamide or other OS groups. Alternatively, the OS
component may be a mixture of an OS polymer having one or more
bicyclic OS groups and one or more additional OS polymers having
one or more polyamide or other OS groups.
[0042] Polymers of the OS component can be of any suitable
structure, including thermoplastic polymers, non-thermoplastic
polymers (e.g., thermosetting), or a mixture of both. Similarly,
polymers of the OS component can be addition polymers, condensation
polymers, polymers that include both condensation and addition
linkages or segments, or mixtures thereof. The configuration of the
polymer backbone may vary depending upon a variety of
considerations, including, for example, the desired properties of a
composition incorporating the OS component, the expected use of the
OS component, other materials that the OS component will contact or
be intermixed with, or the type of OS component desired.
[0043] Non-limiting examples of suitable backbone structures for
polymers of the OS component include polyesters and copolyesters
such as polyethylene terephthalate ("PET"), polybutylene
terephthalate ("PBT"), polyethylene naphthalate ("PEN"),
polybutylene naphthalate ("PBN") and any other suitable esters of
acids and diols; polylactones such as polycaprolactone; polymethyl
methacrylate ("PMMA"); styrene/maleic anhydride ("SMA");
polyoxymethylene ("POM"); ketones such as polyetheretherketone
("PEEK") and polyaryletherketone ("PAEK"); thermoplastic
fluoropolymers; polycarbonate ("PC"); polyurethanes; polyarylate
("PAR"); polyphenylene oxide ("PPO"); polyamides such as nylon 6,
nylon 6,6, nylon 11, nylon 6,12 and nylon 12; imides such as
polyimide ("PI"), polyetherimide ("PEI") and polyamideimide
("PAI"); polyphthalamide; sulfones such as polysulfone ("PSul");
polyarylsulfone ("PAS") and poly ether sulfone ("PES");
polyaminoacids; polydimethylsiloxanes; polyolefins such as
polyethylene ("PE"), polypropylene ("PP"), polybutylene ("PB"), and
polybutadiene ("PBD"); styrenes such as polystyrene ("PS"), poly
.alpha.-methyl styrene and styrene/acrylonitrile ("SAN"); vinyls
such as polyvinyl chloride ("PVC") and polyvinylnaphthalene
("PVN"); mixtures thereof; and copolymers and derivatives thereof
which preferably do not unsuitably interfere with oxygen
scavenging. OS groups may be incorporated into the aforementioned
polymers at any convenient stage, including, for example, during
production of the polymer or as a post-modification. In certain
preferred embodiments, the OS polymers are suitable for contacting
food or beverage products.
[0044] In certain preferred embodiments, the OS component includes
a first OS polymer having a condensation backbone and a plurality
of bicyclic groups. Some examples of suitable condensation backbone
include any of the condensation backbones discussed above (i.e.,
polyester, polyamide, polyurethane, polycarbonate, etc.). Polyester
(including copolyesters) backbones are presently preferred
condensation backbones, with PET being particularly preferred in
certain embodiments.
[0045] For example, a polyester may be formed using one or more
polyols and one or more diacids.
[0046] Suitable diacids include dicarboxylic acid components such
as, but not limited to, adipic acid, terephthalic acid, isophthalic
acid, naphthalic acid, 2,6-naphthalene dicarboxylic acid, other
naphthalene dicarboxylic acid isomers, mixtures of dicarboxylic
acid components, and derivatives thereof. The dicarboxylic acid
components may be present as derivatives, such as, for example,
bis-hydroxyethyl terephthalate. Similarly, other suitable
components may be selected and used in forming other types of
polymers such as polyamide, polyepoxy, and polyurethane
polymers.
[0047] Suitable polyols include, but are not limited to, aliphatic
alcohols, cycloaliphatic alcohols, difunctional alcohols ("diols"),
trifunctional alcohols ("triols"), tetrahydric or higher alcohols,
and combinations thereof. Examples of some suitable polyols include
ethylene glycol, propylene glycol, butylene glycol, neopentyl
glycol, cyclohexane diol, cyclohexane dimethanol, hexane diol,
glycerine, trimethylol propane ("TMP"), di trimethylolpropane,
pentaerythritol, dipentaerythritol, trimethylol ethane, trimethylol
butane substituted propane diols and triols (e.g., 2-methyl,
1,3-propane diol), substituted butane diols and triols, substituted
pentane diols and triols, substituted hexane diols and triols,
diethylene glycol and triols, derivatives thereof, and mixtures
thereof.
[0048] Polymers of the OS component can be of any suitable size.
The OS component preferably includes one or more OS polymers having
a number average molecular weight (M.sub.n) of at least about
1,000, more preferably at least about 1,500, and even more
preferably at least about 2,000. Preferably, the one or more OS
polymers have a M.sub.n of less than about 100,000, more preferably
less than about 50,000, and even more preferably less than about
35,000. In one embodiment, the OS polymer containing the bicyclic
group has a M.sub.n from about 2,000 to about 3,000.
[0049] If desired, the OS component may include one or more
branched or highly-branched OS polymers (e.g., hyperbranched and/or
dendridic polymers). For further discussion of highly branched
oxygen scavenging polymer materials, see International App. No.
PCT/US08/73839 by Joslin et al.
[0050] While not presently preferred, it is contemplated that the
OS component may include one or more non-polymer OS materials such
as, for example, an oligomer, a polymer precursor, and/or a
low-molecular-weight compound. In such embodiments, the non-polymer
OS materials may exhibit a number average molecular weight outside
the aforementioned M.sub.n's. For example, the OS component may
include an OS material having a M.sub.n of less than about 1,000.
Some examples of non-polymer OS materials include Diels-Alder
reaction products of a conjugated diene component (e.g.,
cyclopentadiene) and an unsaturated oil (e.g., linseed oil) such as
the DILULIN product commercially available from Cargill, succinic
anhydride derivatives including one or more OS groups described
herein (e.g., the material of Formula III described below), and
fatty-acid derivatives including one or more OS groups described
herein (e.g., a Diels-Alder reaction product of an unsaturated
fatty acid and cyclopentadiene).
[0051] As previously discussed, bicyclic OS groups of the invention
preferably include at least one double bond, and more preferably at
least one double bond located between atoms of a ring included in
the bicyclic group. Examples of suitable double bonds include
carbon-carbon ("C.dbd.C"), carbon-oxygen ("C.dbd.O"),
carbon-nitrogen ("C.dbd.N"), nitrogen-nitrogen ("N.dbd.N"), and
nitrogen-oxygen (N.dbd.O) double bonds, with C.dbd.C being
preferred.
[0052] While not intending to be bound by theory, it is believed
that such bicyclic OS groups may possess one or more of the
following benefits: enhanced reactivity with oxygen, enhanced
compatibilization of a polymer containing the bicyclic OS group
with other materials, and/or reduced production of mobile oxidative
cleavage fragments. While not intending to be bound by theory, the
carbon-carbon double bonds present in unsaturated bicyclic groups
such as norbornene are believed to exhibit enhanced
oxygen-scavenging kinetics relative to carbon-carbon double bonds
present in conventional acyclic oxygen-scavenging groups. The high
level of ring strain typically present in unsaturated bicyclic
groups is believed to contribute to the enhanced oxygen-scavenging
kinetics. For further discussion of the reactivity of bicyclic
compounds, see, for example, D. E. Van Sickel, F. R. Mayo, R. M.
Arluck JACS (32)1967, 3680 "Bridging of the cyclohexane ring has
thoroughly deactivated the allylic bridgehead hydrogen atoms and
increased the reactivity of the double bond by 8 to ninefold." By
way of example, as discussed in International App. No.
PCT/US08/59562 by Share et al., an unsaturated monomer
functionalized with cyclopentadiene via a Diels-Alder reaction
exhibited excellent oxygen scavenging performance when tested using
a vial test oxygen scavenging methodology, whereas the unmodified
unsaturated monomer did not.
[0053] In preferred embodiments, the bicyclic OS group includes a
bicyclic structure represented by the IUPAC (International Union of
Pure and Applied Chemistry) nomenclature Expression (I):
bicyclo[x.y.z]alkene
[0054] In Expression (I), [0055] x is an integer having a value of
2 or more, [0056] y and z are each an integer having a value of 1
or more, and [0057] the term alkene refers to the IUPAC
nomenclature designation (e.g., hexene, heptene, heptadiene,
octene, etc.) for a given bicyclic molecule.
[0058] In preferred embodiments, x has a value of 2 or 3 (more
preferably 2) and each of y and z independently have a value of 1
or 2.
[0059] Examples of some suitable bicyclic OS groups represented by
Expression (I) include bicyclo[2.1.1]hexene, bicyclo[2.2.1]heptene
(i.e., norbornene), bicyclo[2.2.2]octene, bicyclo[2.2.1]heptadiene,
and bicyclo[2.2.2]octadiene. Bicyclo[2.2.1]heptene is a presently
preferred OS group.
[0060] It is contemplated that the bicyclic OS groups represented
by Expression (I) may contain one or more heteroatoms (e.g.,
nitrogen, oxygen, sulfur, etc.) and may be substituted to contain
one or more additional substituents. For example, one or more
cyclic groups (including, e.g., pendant cyclic groups and ring
groups fused to a ring of a bicyclic OS group) or acyclic groups
may be attached to the bicyclic group represent by Expression
(I).
[0061] The OS component can contain any suitable number of bicyclic
OS groups. While not intending to be bound by any theory, it is
believed that the oxygen-scavenging ability of the bicyclic OS
group is based on the presence of at least one double bond. Thus,
it is believed that the number of bicyclic OS groups present in the
OS component is an important factor in determining its
oxygen-scavenging capacity. A sufficient number of bicyclic OS
groups are preferably included to provide suitable
oxygen-scavenging properties. The number of bicyclic OS groups
included in the OS polymer and/or component may vary depending on a
variety of considerations, including, for example, the intended
application (e.g., the level of oxygen-scavenging capacity and/or
rate desired, including, for example, the level of "initial" oxygen
scavenging upon product packaging, the thickness of an article or
layer in which the OS component is to be employed, the desired
concentration of OS component in an article or composition, etc.)
and the amount and efficacy of other types of oxygen-scavenging
groups present in the OS component.
[0062] The bicyclic OS groups can be located at any suitable
location of a polymer, including, for example, in a backbone, a
pendant group, or at both backbone and pendant locations.
[0063] As discussed above, the OS component preferably further
includes a second OS group in addition to the bicyclic OS group,
which in preferred embodiments is: [0064] (a) a polyamide OS group;
[0065] (b) an unsaturated group (e.g., a non-bicyclic unsaturated
group), preferably including one or more carbon-carbon double
bonds, and more preferably one or more carbon-carbon double bonds
having a heat of hydrogenation of about 32 kcal/mole of less (e.g.,
from about 23 to about 32 kcal/mole, more preferably from 23 to
27.5 (e.g., cyclohexene groups); or [0066] (c) a mixture thereof.
In one embodiment, the second OS polymer does not include
polybutadiene or butadiene segments.
[0067] Polyamide OS groups are preferred second OS groups in
certain embodiments. Examples of suitable polyamide OS groups
include m-xylylene adipamide; hexamethylene isophthalamide;
hexamethylene adipamide-co-isophthalamide; hexamethylene
adipamide-co-terephthalamide; hexamethylene
isophthalamide-co-terephthalamide; or mixtures of two or more of
these. Preferred polyamide groups include those containing groups
of the following formula (A):
-arylene-C(HR.sup.1)--N(R.sup.2)--(C.dbd.O)--, conveniently in
--N(R.sup.3)--C(HR.sup.4)-- arylene-
C(HR.sup.1)--N(R.sup.2)--(C.dbd.O)--R.sup.5--(C.dbd.O)-- units,
where: [0068] R.sup.1, R.sup.2, R.sup.3, and R.sup.4 preferably
each denote one of a hydrogen atom, a substituted or unsubstituted
alkyl group, a substituted or unsubstituted cycloalkyl group, a
substituted or unsubstituted aryl group, or a substituted or
unsubstituted alkenyl group. [0069] R.sup.5 preferably denotes a
divalent organic linking group including, for example, a
substituted or unsubstituted alkyl group, a substituted or
unsubstituted cycloalkyl group, a substituted or unsubstituted aryl
group, or a substituted or unsubstituted alkenyl or cycloakenyl
group. Typically R.sup.5 will have from 1 to 10 carbons and be
straight-chain or branched. In some embodiments, R.sup.5 denotes a
--(CH.sub.2).sub.n-- group where n is preferably from 1 to 10, and
more preferably from 4 to 6. [0070] If desired, the arylene group
in the above formula (A) may be further substituted such as, for
example, alkyl-substituted and/or condensed with other
unsubstituted or alkyl-substituted aromatic rings. Substituted or
unsubstituted phenylene groups such as, for example, substituted or
unsubstituted 1,2- or 1,3-phenylene groups are preferred arylene
groups.
[0071] In a presently preferred embodiment, the polyamide OS group
is a reaction product of m-xylylenediamine and a polycarboxylic
acid such as adipic acid. Poly(m-xylylene adipamide), otherwise
known commercially as MXD6 nylon, is an example of a suitable
polymer including such a polyamide OS group. It is contemplated
that the polyamide OS group may be included in any suitable
polymer, including any of the polymers described herein.
[0072] Examples of suitable unsaturated OS groups may include
cyclopentene, cyclohexene, cycloheptene, cyclooctene (including,
e.g., cis-cyclooctene), and mixtures thereof.
[0073] In a presently preferred embodiment, the OS component
contains a mixture of (i) a first OS polymer, preferably having a
condensation backbone, that preferably includes a plurality of
backbone, terminal, and/or pendant bicyclic OS groups and (ii) a
polyamide OS polymer, more preferably a polyamide polymer
containing a polyamide group of formula (A) such as, for example,
MXD6 nylon. The ratio of the aforementioned first OS polymer to the
polyamide OS polymer may be dictated by a variety of factors
including, for example, cost, compatibility, the end use
application, the desired oxygen-scavenging profile, and the
"concentration" of oxygen-scavenging groups present in the first OS
polymer and/or the polyamide OS polymer. In certain embodiments, a
packaging article may contain from about 0.1 to about 99.9 wt-% of
the first OS polymer and about 0.1 to about 99.9 wt-% of the
polyamide OS polymer, about 0.25 to about 2 wt-% of the first OS
polymer and about 0.5 to about 5 wt-% of the polyamide OS polymer,
or about 0.5 to about 1.0 wt-% of the first OS polymer and about 1
to about 2 wt-% of the polyamide OS polymer, based on the total
weight of the packaging article. The concentrations of the first OS
polymer and the polyamide OS polymer will typically be higher in
the barrier layer(s) of multilayer articles than the barrier layer
of monolayer articles. In some embodiments, the polyamide OS
polymer of the aforementioned weight ranges is all, or
substantially all, MXD6 nylon or the like.
[0074] In presently preferred embodiments, the bicyclic OS group is
formed using a conjugated diene component that is preferably
capable of participating in a Diels-Alder reaction with an
unsaturated component (often referred to as a "dieneophile" in the
context of a Diels-Alder reaction). Diels-Alder reactions (often
referred to as [4+2] cycloadditions) typically involve the addition
of an unsaturated component across the 1,4 positions of a
conjugated diene component to form a cycloaddition reaction product
that is typically cyclic or bicyclic in nature. Typically, at least
one of the conjugated diene and unsaturated components contains one
or more substituents that "activate" the component toward reaction,
although in some instances one or both components can contain a
"deactivating" substituent or substituents. The Diels-Alder
reaction is generally considered to be a concerted reaction, and as
such, either component can be the "electron donor" or "electron
acceptor" depending upon the substituents bonded thereto.
[0075] The conjugated diene component used in the method of the
invention can be any suitable type of compound that contains any
suitable type and combination of conjugated double bonds. Examples
of suitable double bonds include C.dbd.C, C.dbd.O, C.dbd.N,N.dbd.N,
and N.dbd.O double bonds, with C.dbd.C being preferred. The
conjugated double bonds can be present in an acyclic group (e.g.,
butadiene), a cyclic group (including, e.g., cyclic, bicyclic, and
fused rings), or a combination of both. In some embodiments, the
conjugated diene component is present in a polymer or polymer
precursor. In some embodiments, the conjugated diene component
includes an aromatic group preferably capable of participating in a
Diels-Alder reaction. Examples of conjugated dienes capable of
participating in Diels-Alder reactions include anthracene,
butadiene (including, e.g., dimethyl butadiene), cyclohexadiene,
cyclopentadiene (including, e.g., 1-alkyl cyclopentadienes or
2-alkyl cyclopentadienes), furan, isoprene, methyl vinyl ketone,
thiophene, polymers and polymer precursors containing any of these,
derivatives thereof, and combinations thereof.
[0076] Presently preferred conjugated diene components include at
least one ring preferably having about 5 to about 8 atoms in the
ring, and more preferably 5 or 6 atoms in the ring. In a
particularly preferred embodiment, the conjugated diene component
includes at least one 5-member ring, with cyclopentadiene being a
presently preferred 5-member ring.
[0077] In a preferred embodiment, cyclopentadiene is reacted with a
C.dbd.C of an unsaturated component to yield a norbornene
group.
[0078] Suitable unsaturated components of the invention include any
components capable of participating in a Diels-Alder reaction to
form a bicyclic OS group. The unsaturated component can be any
suitable type of compound that contains one or more double or
triple bonds. Examples of suitable double and triple bonds include
C.dbd.C, C.dbd.O, C.dbd.N, N.dbd.N,N.dbd.O, carbon-carbon triple
bonds ("C.ident.C"), and carbon-nitrogen triple bonds
("C.ident.N"), with C.dbd.C bonds being presently preferred. In
some embodiments, the unsaturated component is present in a polymer
or polymer precursor.
[0079] As previously mentioned, the conjugated diene component
and/or the unsaturated component may contain any suitable
electron-donating group, electron-withdrawing group, or a
combination of both. Diels-Alder reactions can typically be
accelerated using groups that activate the reactant pair by making
one of the conjugated diene or unsaturated components more
electron-deficient and the other more electron-rich (e.g., by using
an electron-withdrawing group on one reactant and an
electron-donating group on the other). The electron-withdrawing or
electron-donating effect of a given group on the conjugated diene
or unsaturated components is typically exerted by a group located
within one atom (i.e., alpha) of the reactive double or triple
bond. That is, the electron-donating or electron-withdrawing group
typically does not include an atom of the double or triple bond,
but rather is bonded directly to an atom of the double or triple
bond. Examples of electron-withdrawing groups include carbonyl
(e.g., of an aldehyde, ketone, acid, ester, or amide group),
nitrile, nitro, halo, substituted or unsubstituted aryl,
hydroxy-methyl, amino- or substituted-aminomethyl, cyanomethyl,
halomethyl and vinyl groups. Examples of electron-donating groups
include straight chain, branched chain, and cyclic alkyl, amino,
substituted amino, hydroxyl, and ether groups. In certain
embodiments of the invention, one of the conjugated diene or
unsaturated components contains one or more electron-donating group
whereas the other contains one or more electron-withdrawing
group.
[0080] In one embodiment, an unsaturated polyolefin such as a
polybutadiene polymer (or a polymer containing butadiene or
polybutadiene segments) may be functionalized with bicyclic OS
groups via a Diels-Alder reaction to yield an OS polymer useful in
compositions of the invention.
[0081] OS polymers of the invention may be formed using a wide
array of processes including, for example, reactor polymerization
and reactive extrusion. In reactive extrusion, the components may
be fed into the mixing zone of the extruder. The components may be
mixed together before feeding into the extruder, or may be fed
separately. Preferably, the components will be fed separately. As
part of the extrusion process, the components will be subjected to
elevated temperature, pressure, and shear as the components travel
through the extruder. This process mixes the components, and also
causes the components to react, forming the polymer
composition.
[0082] The one or more bicyclic OS groups can be incorporated into
an OS polymer using any suitable reaction method, including, for
example, (i) forming an OS polymer from a polymer precursor (e.g.,
a monomer or oligomer) containing a preformed bicyclic OS group,
(ii) providing a preformed polymer and then modifying the polymer
to contain the bicyclic OS group, or (iii) combining the reactants
for forming the cyclic OS group with reactants (e.g., monomers
and/or oligomers) for forming the polymer and reacting the combined
reactants to form an OS polymer containing one or more bicyclic OS
groups.
[0083] An example of a method for forming the bicyclic OS group
includes reacting a conjugated diene component with an unsaturated
component to produce a polymer precursor (e.g., a monomer or
oligomer) containing at least one bicyclic OS group. For example,
an addition or condensation monomer containing one of the
conjugated diene component or unsaturated component can be reacted
with the other of the conjugated diene component or unsaturated
component to form a monomer including a bicyclic OS group, whereby
the monomer is capable of being polymerized into a polymer.
Examples of suitable polymer precursors include unsaturated mono-
or poly-acids (or anhydrides or esters thereof), alcohols, amines,
isocyanates, thiols, vinyls, and combinations thereof. In certain
embodiments, the unsaturated component is a polymer precursor in
the form of an unsaturated fatty acid or unsaturated succinic
anhydride derivative.
[0084] In some embodiments, polymer precursors containing at least
one bicyclic OS group are incorporated into a polymer such that at
least one condensation linkage group attaches the polymer precursor
to another portion of the polymer. For example, in one such
embodiment, the polymer precursor may be incorporated into a
backbone of an OS polymer such that a pair of condensation linkage
groups attach the polymer precursor to the backbone.
[0085] In another embodiment of the method of the invention, a
preformed polymer that includes at least one of the unsaturated or
conjugated diene components is provided. For example, a polymer
having one or more double or triple bonds (i.e., the unsaturated
component) capable of participating in a Diels-Alder reaction can
be reacted with a conjugated diene component to form an OS polymer
including one or more bicyclic OS groups, whereby the bicyclic OS
group is located at the former site of the unsaturated component
that participated in the reaction. By way of example, an
unsaturated polyester can be reacted with cyclopentadiene to yield
a polyester having one or more norbornene groups.
[0086] In some embodiments, a cyclopentadiene component is reacted
with an unsaturated component, preferably in the form of a
substituted or unsubstituted alkene, to form a monomer containing
an unsaturated bicyclic structure. Examples of suitable substituted
or unsubstituted alkenes include monounsaturated or polyunsaturated
acids, alcohols, amines, isocyanates, thiols, vinyls, or
combinations thereof. Monounsaturated or polyunsaturated fatty
acids and succinic anhydride derivatives are presently
preferred.
[0087] Suitable unsaturated succinic anhydride derivatives include,
for example, reaction products of maleic anhydride and a
substituted alkene. Suitable substituents for the alkene include,
for example, saturated or unsaturated hydrocarbon chains that may
be (i) linear or branched, and substituted or unsubstituted, as
well as (ii) substituted or unsubstituted phenyl groups. Some of
the substituents on the alkenyl group may be bound together as part
of a ring structure. Preferred succinic anhydride derivatives
include octenyl succinic anhydride (OSA), nonenyl succinic
anhydride (NSA), heptenyl succinic anhydride (HSA), and the like.
OSA, shown below in Formula (II), is particularly preferred.
##STR00001##
[0088] The benefits of using an unsaturated succinic anhydride
derivative may include: ease of processing, general availability at
low cost, ability to co-polymerize, compatibility with many
polymers and monomers for reaction, stability during storage, and
low toxicity. Unsaturated succinic anhydride derivatives may be
reacted with a wide variety of materials, depending upon the type
of polymer backbone desired. For example, a succinic anhydride
derivative can be reacted with an alcohol or glycol to form a
polyester. As another example, a succinic anhydride derivative may
be reacted with an amine to form a polyamide.
[0089] For further information regarding unsaturated succinic
anhydride derivatives and their use in forming polymers, see US
Pub. No. 2006/0202161 by Share et al., which is incorporated herein
by reference in its entirety.
[0090] While not wishing to be bound to any theory, Formula (III)
below shows a preferred Diels-Alder reaction product that is
believed to result from reacting OSA with cyclopentadiene.
[0091] The structure of Formula (III) is non-limiting with respect
to stereochemistry and is intended to encompass all possible
stereoisomers. As shown in Formula (III), the reaction product of
OSA and cyclopentadiene is believed to include a norbornene
bicyclic group.
##STR00002##
[0092] In some embodiments, unsaturated fatty acids are reacted
with a conjugated diene component to form fatty acids containing
one or more unsaturated bicyclic OS groups. Examples of suitable
fatty acids include mono- or polyunsaturated fatty acids such as
arichidonic, eleostearic, erucic, licanic, linoleic, linolenic,
oleic, palmitoleic, ricinoleic acid, and mixtures thereof. Other
useful fatty acids may include mixtures of saturated and
unsaturated fatty acids such as, for example, fatty acids from
natural or modified oils such as linseed oil, soybean oil,
sunflower oil, safflower oil, castor oil, and mixtures thereof. In
a presently preferred embodiment, linoleic acid is reacted with
cyclopentadiene in a Diels-Alder reaction to form a reaction
product having at least one bicyclic OS group (which is believed to
be a norbornene group).
[0093] Any suitable Diels-Alder reaction techniques or conditions
can be employed to produce bicyclic OS groups of the invention. By
way of example, a Diels-Alder reaction using cyclopentadiene to
produce a bicyclic OS group can be carried out in a number of ways,
including, for example, (i) combining dicyclopentadiene and an
unsaturated component in a reaction vessel or (ii) separately
cracking dicyclopentadiene to generate cyclopentadiene and then
combining the cyclopentadiene and an unsaturated component in a
reaction vessel.
[0094] By way of example, a suitable reaction product of
dicyclopentadiene and an unsaturated component may be made using a
Diels-Alder reaction process as follows: An unsaturated component
is charged into a closed reactor purged with an inert gas such as
nitrogen. The unsaturated component is heated to about 260.degree.
C. with constant stirring and dicyclopentadiene is added at a
steady rate to the heated unsaturated component. While not
intending to be bound by any theory, it is believed that the
dicyclopentadiene dedimerizes into two molecules of cyclopentadiene
in the reactor vessel, which then react with the double bonds of
the unsaturated component. After the addition of the
dicyclopentadiene is complete, heating of the reaction mixture is
continued at a temperature of preferably not more than about
300.degree. C., and even more preferably not more than about
275.degree. C., for about 0.25 hour to about 5 hours. The reaction
is generally permitted to proceed until substantially all of the
cyclopentadiene has reacted with the unsaturated component.
Thereafter, the reaction product is cooled and removed from the
reaction vessel. For further discussion of Diels-Alder reaction
conditions suitable for use with dicyclopentadiene, see for
example, U.S. Pub. No. 2003/0036486, U.S. Pat. No. 5,693,715, and
U.S. Pat. No. 5,288,805, which are incorporated herein by reference
in their entirety.
[0095] In another aspect, the invention provides an OS composition
containing an OS component that includes (i) a "fast" OS group such
as an unsaturated OS group, preferably an unsaturated cyclic OS
group, having a relatively high heat of hydrogenation (e.g., above
that of cyclohexene in certain embodiments) and (ii) a second OS
group, preferably an OS group having a "long-lasting" (e.g.,
months, years, etc.) oxygen-scavenging effect such as, for example,
polyamide OS groups such as that of formula (A) described above.
While not intending to be bound by theory, it is believed that the
desirable scavenging profile (e.g., the combination of initial and
medium-term/long-term oxygen scavenging properties) of certain
preferred OS compositions of the invention is attributable, at
least in part, to the inclusion of an unsaturated OS groups having
a relatively high heat of hydrogenation (such as, e.g., an
unsaturated bicyclic group). As discussed in International App. No.
PCT/US08/59562 by Share et al., heat of hydrogenation is believed
to be a useful measure of the relative suitability of OS groups in
which double bonds are responsible, at least in part, for the
oxygen-scavenging propensity of a material including the group.
While not intending to be bound by theory, it is believed that the
heat of hydrogenation of a double bond of an unsaturated group
corresponds to the propensity of the unsaturated group to scavenge
oxygen, with a higher heat of hydrogenation indicating a greater
propensity to scavenge oxygen. For further discussion of heats of
hydrogenation see, for example, V.V. Voronenkov, Russian Chemical
Reviews, 44 (4), 1975.
[0096] In some embodiments, the OS component includes an
unsaturated cyclic OS group (which can be a bicyclic or a
non-bicyclic cyclic OS group) having one or more rings, at least
one of which is preferably an unsaturated ring having one or more
double bonds (preferably carbon-carbon double bonds) located
between atoms of the ring. The double bond preferably has a heat of
hydrogenation greater than that of cyclohexene, more preferably at
least about as high as that of bicyclo[2.2.2]octene, and even more
preferably at least about as high as that of bicyclo[2.2.1]heptene.
The upper end of the heat of hydrogenation is not particularly
limited and can be any suitable heat of hydrogenation for a given
application. In some embodiments, the double bond has a heat of
hydrogenation of at least about 32 kcal/mole.
[0097] As used herein, when a heat of hydrogenation is stated to
be, for example, "at least X," "greater than X," or the like, it
should be understood that reference is made to the absolute value
of the heat of hydrogenation because heats of hydrogenation are
typically reported as negative values, with a larger negative value
indicating a higher heat of hydrogenation (e.g., -40 kcal/mole is a
higher heat of hydrogenation than -10 kcal/mole).
[0098] Examples of unsaturated cyclic OS groups having a heat of
hydrogenation greater than that of cyclohexene include bicyclic
groups such as bicyclo[2.2.1]heptene, bicyclo[2.2.2]octene,
bicyclo[2.2.2]octadiene, bicyclo[2.2.1]heptadiene; and non-bicyclic
groups such as methylenecyclobutane, ethylidenecyclopropane, and
1,2-dimethylcyclopropene. Table 1 below provides the heat of
hydrogenation values for a variety of unsaturated molecules. The
heat of hydrogenation values reported in Table 1 were obtained from
the following published literature sources: R. B Turner, W. R.
Meador, R. R. Winkler, J. Am. Chem. Soc., (79) p. 4116 (1957); R.
B. Turner, A. D. Jarrett, P. Goebel, B.J. Mallon, J. Am. Chem. Soc,
(95), p. 790 (1973); and R. B. Turner, W. R. Meador, J. Am. Chem.
Soc., (79) p. 4133 (1957); and William H. Brown, Cristopher S.
Foote, Brent L. Iverson, Organic Chemistry, p 784 (2005).
TABLE-US-00001 TABLE 1 Heat of Hydrogenation Molecule (kcal/mole*)
cis-Cyclooctene -22.98 Cycloheptene -25.85 Cyclopentene -26.04
Cyclohexene -27.10 trans-2-Butene -27.62 Bicyclo[2.2.2]octadiene**
-56.21 (-28.11) Bicyclo[2.2.2]octene -28.25 cis-2-Butene -28.57
Methylenecyclobutane -29.43 1-Butene -30.3 Bicyclo[2.2.1]heptene
-33.13 Bicyclo[2.2.1]heptadiene** -68.11 (-34.06)
Ethylidenecyclopropane -37.01 1,2-Dimethylcyclopropene -43.3 *Data
is reported in kilocalories per mole of each molecule. **For these
molecules, the heat of hydrogenation value includes the heat of
hydrogenation for two carbon-carbon double bonds present in each
molecule. The heat of hydrogenation value for each carbon-carbon
double bond will typically be approximately one-half that of the
entire molecule, and is the value reported in parentheses. While
not intending to be bound by any theory, factors such as resonance
effects will lower the heat of hydrogenation for a conjugated
polyene relative to the respective non-conjugated isomer.
[0099] As evidenced by the data in Table 1, bicyclic structures
such as, for example, bicyclo[2.2.1]heptene and
bicyclo[2.2.2]octene and non-bicyclic structures such as, for
example, methylenecyclobutane and ethylidenecyclopropane exhibit a
higher heat of hydrogenation than cyclohexene. It is believed that
the heat of hydrogenation for molecules such as those listed in
Table 1 is a strong indicator of the propensity of the molecule to
scavenge oxygen when included as a covalently attached group in a
polymer. Thus, for example, a polymer including an OS group having
a heat of hydrogenation at least as great as that of
bicyclo[2.2.1]heptene may exhibit robust initial oxygen-scavenging
properties (e.g., when combined with a suitable amount of oxidation
catalyst) in the absence of a costly aging period (which is
required for certain conventional oxygen-scavenging materials).
[0100] The heat of hydrogenation for an OS group may be determined
using the techniques described in the literature sources of Table
1. Typically, the heat of hydrogenation for a molecule is
substantially the same as the heat of hydrogenation value for the
molecule when present as a group of a polymer, although it is
possible that other moieties present on a polymer may interfere
with the determination of the heat of hydrogenation value for the
group of interest. Thus, one useful approach for determining the
heat of hydrogenation value for an oxygen-scavenging group of a
polymer is to determine (either experimentally using known methods
or by consulting reported literature values) the heat of
hydrogenation value for a molecule having the structure of the
oxygen-scavenging group. If more than one double bond is present in
the oxygen-scavenging group, appropriate steps should preferably be
taken to normalize the heat of hydrogenation per double bond
present.
[0101] OS compositions of the invention preferably include the OS
component described herein and one or more optional oxidation
catalysts. In some embodiments, the OS composition further includes
one or more optional additional polymers or additives.
[0102] An optional oxidation catalyst is preferably included in OS
compositions of the invention. In some embodiments, the oxidation
catalyst may enhance the oxygen-scavenging properties of the OS
component by catalyzing an oxygen-scavenging reaction involving OS
groups of the OS component.
[0103] A broad variety of metallic and organic compounds can
catalyze the oxygen scavenging effect of certain OS groups, and an
appropriate compound may be selected based on any of cost,
compatibility with the OS component, compatibility with other
polymers or ingredients in a blend, and compatibility with other
layers in a multi-layered article. Examples of suitable oxidation
catalysts include transition metals, complexes of transition
metals, photoinitiators and the like, and mixtures thereof.
[0104] Examples of suitable oxidation catalysts include transition
metals such as cobalt, iron, nickel, aluminum, ruthenium, rhodium,
palladium, antimony, osmium, iridium, platinum, copper, manganese,
and zinc, as well as oxides, salts or complexes of these metals,
and mixtures thereof. For example, cobalt II salts of short chain
acids such as acetic acid or terephthalic acid, or long chain acids
such as neodecanoic, stearic, 2-ethyl hexanoic, or octenyl succinic
acid may be used. Salts of inorganic acids may also be used. For
example, antimony chloride III, antimony chloride V, and cobalt
chloride may be used. Preferred catalysts include salts of cobalt
and long chain acids such as, for example, cobalt acetate, cobalt
neodecanoate, cobalt stearate, cobalt octoate, and mixtures
thereof.
[0105] When included, the oxidation catalyst is preferably present
in an amount sufficient to catalyze the oxygen-scavenging ability
of the OS component in the end use application. The amount used
will depend partially upon the catalyst chosen. In general,
however, when using transition metal catalysts or complexes, the
amount of transition metal catalyst or complex present in the end
use application (e.g., in a monolayer article or in a layer of a
multilayer article) may suitably be greater than about 10 ppm by
weight, preferably greater than about 25 ppm by weight, and more
preferably greater than about 35 ppm by weight, based on the total
amount of transitional metal in the catalyst or complex relative to
the total weight of the composition. The amount of transition metal
catalyst or complex present in the end use application may suitably
be less than about 10,000 ppm by weight, preferably less than about
1,000 ppm by weight, and more preferably less than about 600 ppm by
weight, based on the total amount of transitional metal in the
catalyst or complex relative to the total weight of the
composition. In general, when using a photoinitiator or blend of
photoinitiators, the amount of photoinitiator present may suitably
be greater than about 0.01% by weight, and preferably greater than
about 0.1% by weight of the total composition. The amount of
photoinitiator present may suitably be less than about 10% by
weight, and preferably less than about 5% by weight of the total
composition.
[0106] The amount of oxidation catalyst present in the OS
composition of the invention may vary widely depending upon, for
example, the amount of OS composition to be included in an article.
For example, if a monolayer article or layer(s) of a multilayer
article is to be formed from neat OS composition (i.e., 100 wt-% OS
composition), and a transition metal catalyst or complex is to be
used, then the amount of transition metal catalyst or complex
present in the OS composition is preferably as described above for
a desired end use application. If, however, the OS composition is
to be diluted with additional material in forming the monolayer
article or layer(s), then the OS composition preferably includes a
higher concentration of catalyst to account for dilution. Thus, for
example, in an embodiment where an OS composition is to be diluted
twenty-fold in an end use, the OS composition preferably has a
catalyst concentration that is about twenty times higher than the
catalyst concentration desired in the end use. Moreover, depending
upon the approach employed in such embodiments, portions of the OS
composition may have even higher concentrations of catalyst than
that of the overall blend. For example, in some embodiments where
the OS composition is a blend of two or more different types of
particles, all or substantially all of the catalyst may be
introduced into the blend through incorporation of a catalyst
concentrate particle into the blend.
[0107] Compositions of the invention will typically include one or
more optional polymers in addition to any polymers of the OS
component. These additional polymers can be thermoplastic,
non-thermoplastic (e.g., thermosetting), or a mixture of both.
Examples of such suitable polymers include any of the polymer types
described above in regards to the OS component. In certain
embodiments, the one or more additional polymers are preferably
formable polymers useful in forming a packaging article and are
preferably suitable for contacting food or beverage products. The
one or more additional polymers also preferably exhibit a suitable
level of compatibility with the materials of the OS component.
[0108] In some embodiments, the OS composition comprises a blend of
the OS component and one or more additional polymers (e.g. base
and/or structural polymers), wherein the OS composition comprises
from about 99 to about 1 wt-% of the OS component and from about 1
to about 99 wt-% of the one or more additional polymers, from about
95 to about 5 wt-% of the OS component and from about 5 to about 95
wt-% of one or more additional polymers, from about 90 to about 10
wt-% of the OS component and from about 10 to about 90 wt-% of one
or more additional polymers, or from about 80 to about 20 wt-% of
the OS component and from about 20 to about 80 wt-% of the one or
more additional polymer. In a presently preferred embodiment, the
one or more additional polymers are polyesters, and more preferably
PET.
[0109] In general, any suitable material can be added to the OS
compositions of the invention that produces a desired result. For
example, fillers, processing aids, plasticizers, fire retardants,
anti-fog agents, crystallization aids, impact modifiers, surface
lubricants, denesting agents, stabilizers, antioxidants,
ultraviolet light absorbing agents, catalyst deactivators,
colorants, nucleating agents, acetaldehyde reducing compounds,
reheat enhancing aids, fillers, anti-abrasion additives, and the
like, and combinations thereof can be included. In one embodiment,
the OS composition includes the OS component described, an
oxidation catalyst, an additional polymer (e.g., a structural base
polymer) and a colorant.
[0110] Another aspect of the invention is an article incorporating
OS compositions of the invention. OS compositions of the invention
are particularly useful in oxygen-scavenging layers (also referred
to as "oxygen barrier layers") of packaging articles. Packaging
articles incorporating the OS composition of the invention can be
used to package any product for which it is desirable to inhibit
exposure to oxygen during storage. Examples of such products
include certain food or beverage products (e.g., fruit juices,
wine, beer, meat, etc.), pharmaceuticals, medical products,
corrodible metals, and electronic devices.
[0111] Examples of packaging articles include bottles (including
bottle crowns, caps, and other closures), cups, bowls, cartons
(including, e.g., paperboard or fiberboard cartons), containers,
films, wraps (including, e.g., meat wraps), liners (e.g., crown,
cap, or closure liners), coatings, trays, and flexible bags for
industrial, commercial, medical, or residential use. The packaging
articles may be rigid or flexible based on, for example, the number
and type(s) of layers, the method of formation of the packaging
article, and other relevant parameters. The articles may be formed
by using the OS composition alone, by using a blend of the OS
composition with one or more other polymers, or by using a
multi-layer construction incorporating one or more layers including
the OS composition.
[0112] Additionally, the OS composition may be used as a coating,
as a lining, or as part of a blend for a coating or lining of
another article, such as a can, bottle, or container coating or
lining. In some embodiments, the OS composition may be applied
(either directly or via one or more intermediate layers) to a
substrate such as a metal, plastic, fiberboard, or paperboard
substrate.
[0113] If desired, the OS composition (which, in some embodiments,
is the OS component alone and/or in combination with an oxidation
catalyst) may be dissolved in a suitable solvent to form a coating
solution or may be blended with water and/or a suitable organic
solvent to form a coating dispersion. The coating solution or
dispersion may be applied using any suitable method, including, for
example, spraying the coating solution or dispersion onto a surface
of an article and drying the coating to form an oxygen-scavenging
coating. If desired, the coating solution or dispersion may be
applied between layers of another suitable material to form an
oxygen-scavenging film.
[0114] Alternatively, the OS composition may be blended with a
compatible polymer to form an oxygen-scavenging article, or may be
used as an oxygen-scavenging layer in a multi-layered package
construction.
[0115] Packaging articles incorporating OS compositions of the
invention can be of any desired construction. The packaging
articles can be formed from multiple layers of material (referred
to as "multilayer" articles) or a single layer of material
(referred to as "monolayer" articles). The packaging articles can
include a single structural layer or a structural layer and one or
more additional layers. The one or more additional layers can be,
for example, a gas barrier layer (e.g., a layer incorporating a
passive barrier material such as an ethylene-vinyl alcohol
copolymer ("EVOH")), an oxygen-scavenging layer, a food-contact
layer, a structural layer, an adhesive layer, or any layer that
combines one or more of these, alone or in any combination.
Multilayer packaging articles are typically prepared using
coextrusion, injection molding, injection blow molding, stretch
blow molding, coating, or lamination, among other techniques.
Monolayer packaging articles are typically prepared by solvent
casting, injection molding, blow molding, or by extrusion, among
other techniques. A monolayer article is an article formed of
substantially the same composition throughout.
[0116] A multilayer article may be produced that includes the OS
composition in one or more layers. In some embodiments, a
multilayer article may benefit from (i) placing one or more layers
of another material between the atmosphere and the OS composition
and/or (ii) placing one or more layers of another material between
a packaged product and the OS composition. An outer layer of one or
more layers may, for example, protect the OS composition from
physical damage and assist in blocking or reducing migration of
oxygen through a wall of the article. In such constructions, the OS
composition will preferably scavenge any oxygen that penetrates the
one or more layers located between the atmosphere and the OS
composition. In addition, the OS composition is also preferably
capable of scavenging oxygen that may be present inside a packaged
product or within a headspace of the packaging article (if
present).
[0117] The OS composition of the invention may be deployed neat to
form an oxygen-scavenging layer of a monolayer or multilayer
packaging article. Or, alternatively, prior to formation of the
oxygen-scavenging layer of the packaging article, it can be blended
(e.g., in the feedthroat of an extruder prior to article formation)
with one more additional polymers or additives, which may, for
example, reduce transportation and storage costs and/or help
preserve the oxygen-scavenging capacity of the OS composition.
[0118] Articles of the invention can include any suitable amount of
OS component. The amount of OS component included in such articles
may vary depending upon a variety of considerations such as, for
example, the desired oxygen-scavenging properties of the article,
the efficacy of the OS component, cost, and the desired article
properties. In preferred embodiments, monolayer or multilayer
articles of the invention preferably include at least about 0.1
wt-%, more preferably at least about 0.5 wt-%, and even more
preferably at least about 1.0 wt-% of the OS component of the
invention, based on the total weight of the monolayer or multilayer
article. In general, a monolayer or multilayer article will
typically include less than about 15 wt-%, more preferably less
than about 10 wt-%, and even more preferably less than about 5 wt-%
of the OS component of the invention, based on the total weight of
the monolayer or multilayer article. Nonetheless, it is
contemplated that the OS component may constitute, on a weight
basis, all or substantially all of the material of the packaging
article if desired. For example, in some embodiments, bicyclic OS
groups of the invention may be present on a base polymer (e.g., a
structural polymer) of the article.
[0119] In some embodiments, a monolayer article is provided that
includes about 85 wt-% or more of one or more base polymers (e.g.,
a polyester such as PET, a polyolefin, etc.) and about 15 wt-% or
less of OS component, more preferably about 90 wt-% or more of one
or more base polymers and about 10 wt-% or less of OS component,
and even more preferably about 95 wt-% or more of one or more base
polymers and about 5 wt-% or less of OS component. In one such
embodiment, the monolayer articles includes about 85 wt-% or more
of one or more polyester base materials and about 15 wt-% or less
of an OS component that includes a mixture of a polyamide OS
polymer and an OS polymer having a bicyclic OS group of the
invention.
[0120] Articles containing the OS composition of the invention are
preferably storage stable for a prolonged period of time (e.g., at
least days, weeks, or months) under normal atmospheric conditions
(e.g., ambient temperature, ambient humidity, and/or atmospheric
air) without exhibiting unsuitable degradation in oxygen-scavenging
properties, thereby avoiding costly storage techniques (e.g.,
storage under nitrogen gas, refrigeration, dessication, etc.)
frequently associated with certain oxygen-scavenging articles.
[0121] In some embodiments, to preserve oxygen-scavenging capacity,
the OS component invention is combined with oxidation catalyst just
prior to, or during, formation of an oxygen-scavenging layer of a
packaging article. Such a timing of oxidation catalyst addition may
result in enhanced storage stability for OS components and/or
compositions of the invention prior to article formation.
[0122] In some embodiments, the OS composition of the invention may
include two or more parts, in which one or more part includes the
OS component and a different part includes the optional oxidation
catalyst. In one such embodiment, the composition is a blend of two
or more types of particles (preferably thermoplastic particles such
as thermoplastic pellets, flakes, powder, etc.) where (a) a first
particle includes a blend of the OS component and an optional first
polymer, (b) a second particle includes a blend of an oxidation
catalyst and an optional second polymer, and (c) the optional first
and second polymers are the same or different. The first particle
may include any suitable amount of transitional metal catalyst or
complex, including, for example, from about 1,000 ppm to about
40,000 ppm, from 5,000 ppm to about 30,000 ppm, or from about
10,000 ppm to about 25,000 ppm, based on the total amount of
transitional metal in the catalyst or complex present in the first
particles relative to the total weight of the first particles. In
some embodiments, the second particles may be free, or
substantially free, of oxidation catalyst. The above first and
second particles may be combined at any suitable time to form a
blend. For example, the above first and second particles may be
combined to form a blend that may be stored for a period of time
(e.g., days, weeks, months, etc.) before forming an article that
includes the blend. Alternatively, the above first and second
particles may be combined to form a blend just prior to forming an
article from the blend, such as, for example, in the feedthroat of
an injection molding machine or extruder. Thus, in some
embodiments, the OS composition may be provided as a two-part (or
more) kit or system including the above first and second particles,
where the above first and second particles are not (or
substantially are not) in contact with other.
[0123] Monolayer and multilayer articles of the invention may be
formed from compositions of the invention using any suitable
method. Examples of suitable methods include extrusion processes
(including, e.g., co-extrusion), lamination processes, injection
processes (including, e.g., co-injection), application of liquid
coating compositions to at least a portion of a substrate, or a
combination thereof. One or more precursor or intermediate
articles, such as for example a preform, may be formed in route to
the finished article.
[0124] In certain embodiments, to facilitate incorporation of the
oxygen-scavenging materials described herein into an article, solid
thermoplastic particles (e.g., pellets, flakes, powder, etc.) are
formed which include the OS component described herein. Such
thermoplastic particles may be formed, for example, by melt
blending the OS component with a thermoplastic polymer and/or an
oxidation catalyst and pelletizing the resulting blend. In some
embodiments, the thermoplastic particles may be formed from the OS
polymer(s) alone.
EXAMPLES
[0125] The invention is illustrated by the following examples. It
is to be understood that the particular examples, materials,
amounts, and procedures are to be interpreted broadly in accordance
with the scope and spirit of the invention as set forth herein.
Unless otherwise indicated, all parts and percentages are by weight
and all molecular weights are weight average molecular weight.
Unless otherwise specified, all chemicals used are commercially
available from, for example, Sigma-Aldrich, St. Louis, Mo.
Examples 1-3
Preparation of Polymer Precursors
Example 1
[0126] A polymer precursor containing a bicyclic OS group in the
form of a norbornene group was prepared as follows using 1.0 mole
of trimethylol propane ("TMP") and 1.1 mole of
cyclopentadiene-modified linseed oil fatty acid:
[0127] To a 4-neck round-bottom flask equipped with a mechanical
stirrer, a packed column, Dean-Starke trap, condenser, and a
thermocouple connected to a temperature control device, were added
405 parts of cyclopentadiene-modified linseed oil fatty acid (a
Diels-Alder reaction product of cyclopentadiene and linseed oil
fatty acids), 95 parts of TMP, and 0.5 parts of FASCAT 4201 (a
dibutyltin oxide catalyst commercially available from Atofina). The
mixture was heated to 210.degree. C. over the course of about 70
minutes. After heating the mixture for an additional 4 hours, the
mixture had an acid number of 0.8 and a hydroxyl number of 146. The
mixture was then cooled and discharged from the flask.
Example 2
[0128] A polymer precursor containing a cyclic OS group in the form
of a norbornene group was prepared as follows using 1.0 mole of
pentaerythritol and 2.1 mole of cyclopentadiene-modified linseed
oil fatty acid:
[0129] To a 4-neck round-bottom flask equipped with a mechanical
stirrer, a packed column, Dean-Starke trap, condenser, and a
thermocouple connected to a temperature control device, were added
1981.8 parts of dicyclopentadiene-modified linseed oil fatty acid
(a Diels-Alder reaction product of dicyclopentadiene and linseed
oil fatty acids), 274.4 parts pentaerythritol, and 2.2 parts FASCAT
4201. The mixture was heated to 210.degree. C. over the course of
about 3 hours. After heating the mixture for an additional 2 hours,
the mixture had an acid number of 2 and a hydroxyl number of 90.
The mixture was then cooled and discharged from the flask.
Example 3
[0130] A polymer precursor containing a cyclic OS group in the form
of a norbornene group was prepared as follows using 2 moles of
ethylene glycol and 1 mole of a Diels-Alder reaction product of
cyclopentadiene and octenylsuccinic anhydride (referred hereinafter
as "cyclopentadiene adduct of OSA"):
[0131] To a 4-neck round-bottom flask equipped with a mechanical
stirrer, a packed column, Dean-Starke trap, condenser, and a
thermocouple connected to a temperature control device, were added
372.5 parts of cyclopentadiene adduct of OSA, 127.5 parts of
ethylene glycol, and 0.5 grams of FASCAT 4201. This mixture was
heated to 220.degree. C. over the course of about 2.5 hours. After
4 hours total at 220.degree. C., the mixture had an acid number of
2.4 and a hydroxyl number of 179. The mixture was cooled and
discharged at 150.degree. C. from the flask.
Examples 4-8
Preparation of Polyester OS Polymers
Example 4
[0132] To a 4-neck round-bottom flask equipped with a mechanical
stirrer, a packed column, Dean-Starke trap, condenser, and a
thermocouple connected to a temperature control device, were added
435.5 parts of the polymer precursor of Example 1 and 64.5 parts of
adipic acid. The mixture was heated to 210.degree. C. over the
course of about 2.5 hours. After 5 hours total at 210.degree. C.,
the mixture had an acid number of 2.4 and a hydroxyl number of
31.5. The mixture was then cooled and discharged at 150.degree. C.
from the flask.
Example 5
[0133] To a 4-neck round-bottom flask equipped with a mechanical
stirrer, a packed column, Dean-Starke trap, condenser, and a
thermocouple connected to a temperature control device, were added
428 parts of the polymer precursor of Example 1 and 72 parts of
adipic acid. The mixture was heated to 210.degree. C. over the
course of about 1.5 hours. The temperature of the mixture was
raised to 220.degree. C. and held for about 5.5 hours--at which
point the mixture had an acid number of 1.8 and a hydroxyl number
of 26.2. The mixture was cooled and discharged at 150.degree. C.
from the flask.
Example 6
[0134] To a 4-neck round-bottom flask equipped with a mechanical
stirrer, a packed column, Dean-Starke trap, condenser, and a
thermocouple connected to a temperature control device, were added
460.5 parts of the polymer precursor of Example 2 and 39.5 parts of
adipic acid. This mixture was heated to 210.degree. C. over the
course of about 1.5 hours. The temperature of the mixture was
raised to 220.degree. C. After about 2 hours total at 220.degree.
C., the mixture had an acid number of 2.1 and a hydroxyl number of
19.4. The mixture was cooled and discharged at 150.degree. C. from
the flask.
Example 7
[0135] To a 4-neck round-bottom flask equipped with a mechanical
stirrer, a packed column, Dean-Starke trap, condenser, and a
thermocouple connected to a temperature control device, were added
455.5 parts of polymer precursor of Example 2 and 44.5 parts of
isophthalic acid. This mixture was heated to 220.degree. C. over
the course of about 1.5 hours. After about 6.5 hours total at
220.degree. C., the mixture had an acid number of 2.9 and a
hydroxyl number of 23.2. The mixture was then cooled and discharged
at 150.degree. C. from the flask.
Example 8
[0136] To a 4-neck round-bottom flask equipped with a mechanical
stirrer, a packed column, Dean-Starke trap, condenser, and a
thermocouple connected to a temperature control device, were added
400 parts of the polymer precursor of Example 3 and 78.5 parts of
adipic acid. This mixture was heated to 220.degree. C. over the
course of about 2.5 hours. After about 3 hours total at 220.degree.
C., the mixture had an acid number of 4.0. The mixture was then
cooled and discharged at 150.degree. C. from the flask.
Oxygen Scavenging Properties of the Polyester OS Polymers of
Examples 4-8
[0137] A sample of 150 milligrams ("mg") of each of the polymer
compositions of Examples 4-8 was mixed with 1,000 ppm of cobalt
catalyst (6% w/w Cobalt Ten-Cex). The samples were each sealed in a
6 ml glass airtight vial containing ambient atmospheric air (i.e.,
about 21% oxygen). After 16 hours at ambient temperature, the
amount of residual oxygen in the vials was measured using an Ocean
Optics Foxy Oxygen Sensor System (available from Ocean Optics of
Dunedin, Fla.), which uses fluorescence quenching to measure oxygen
content. The results were measured after 2 minutes of exposure to
the sensor. The results are provided below in Table 1.
TABLE-US-00002 TABLE 1 % Residual Oxygen at 16 Hours Material Vial
1 Vial 2 Mean Example 4 0.9 1.7 1.3 Example 5 2.2 2 2.1 Example 6
2.2 0.6 1.4 Example 7 2.4 4.1 3.3 Example 8 1.2 2 1.6 C1* 22 21.3
21.7 *An empty control vial containing only atmospheric air was
included as a negative control.
[0138] As shown in Table 1, good oxygen scavenging was observed for
the compositions of Examples 4-8, which each included cyclic OS
groups in the form of norbornene groups.
Example 9
[0139] In the following example, an oxygen scavenging polyester
polymer is produced by first making an unsaturated polyester and
then reacting carbon-carbon double bonds of the polyester with
cyclopentadiene.
Example 9.1
[0140] To a 4-neck round-bottom flask equipped with a mechanical
stirrer, Dean-Starke trap, condenser, and a thermocouple connected
to a temperature control device, were added 4839.6 parts of linseed
oil fatty acid, 1160.4 parts pentaerythritol, and 6.0 parts FASCAT
4201 catalyst. The mixture was heated to 170.degree. C. over the
course of about 3 hours. After heating slowly to 200.degree. C. and
holding for 2 hours, the mixture had an acid number of 1.0 and a
hydroxyl number of 157. The mixture was then cooled and discharged
from the flask. 287 parts of water were collected.
Example 9.2
[0141] To a 4-neck round-bottom flask equipped with a mechanical
stirrer, Dean-Starke trap, condenser, and a thermocouple connected
to a temperature control device, were added 2281.2 parts of the
adduct of Example 9.1 and 317 parts adipic acid. The mixture was
heated to 210.degree. C. over the course of about 6 hours. After
holding for 4 hours, the mixture had an acid number of 2.4 and a
hydroxyl number of 47.9. The mixture was then cooled and filtered
through a 25 micron bag. 65 parts of water were collected.
Example 9.3
[0142] 73.3 parts of the polymer prepared in Example 9.2 were
placed in a Parr reactor with 26.7 parts of dicyclopentadiene. The
reactor was heated to 240.degree. C. over the course of 1 hour, and
the pressure reached 50 psi (345 kPa). The reactor was held at
240.degree. C. for 1 hour as the pressure became constant at 20 psi
(138 kPa). The reactor was then vented and sparged with nitrogen
for 1 hour, followed by vacuum at 29 inches of Hg (98.2 kPa) while
holding at 240.degree. C. The batch was then cooled and
discharged.
Oxygen Scavenging Properties of the OS Polyester Polymer of Example
9
[0143] 200 milligram ("mg") samples of the polyester polymer
composition of Examples 9 were each mixed with 1,000 ppm of cobalt
catalyst (6% w/w Cobalt Ten-Cex). The samples were each sealed in a
6 ml glass airtight vial containing ambient atmospheric air (i.e.,
about 21% oxygen). After 16 hours at ambient temperature, the
amount of residual oxygen in the vials was measured using an Ocean
Optics Foxy Oxygen Sensor System (available from Ocean Optics of
Dunedin, Fla.), which uses fluorescence quenching to measure oxygen
content. The results were measured after 2 minutes of exposure to
the sensor. The results are provided below in Table 2.
TABLE-US-00003 TABLE 2 % Residual Oxygen at 16 Hours Material Vial
1 Vial 2 Vial 3 Mean Example 1 Run 1 3.3 2.3 2.5 2.7 Example 1 Run
2 1.6 5.1 4.1 3.6 C1* 20.8 21.5 21.4 21.2 *An empty control vial
containing only atmospheric air was included as a negative control.
Theoretical oxygen concentration is 20.9%.
[0144] As shown in Table 2, good oxygen scavenging was observed for
a composition including the polyester polymer of Example 9 (which
is believed to include cyclic OS groups in the form of norbornenc
groups).
Example 10
Articles
[0145] A nylon masterbatch consisting of between 40-60 wt-% MXD6
nylon (Mitsibushi) and 60-40 wt-% PET was compounded in a twin
screw extruder. In addition, a cobalt masterbatch containing PET
and cobalt neodecanoate with a cobalt concentration of 5000-15000
ppm was compounded in a twin screw extruder. The two masterbatches,
as well as the liquid OS polyester of Example 9 were added directly
into the feedthroat of an injection molding machine, along with
additional PET, to produce 38.5 gram preforms with a 38 mm finish.
Comparative preforms were also made using (i) neat PET; (ii) a
mixture of PET, the MXD6 nylon masterbatch and the cobalt
masterbatch, and (iii) a mixture of PET, the liquid OS polyester of
Example 9 and the cobalt materbatch. These preforms were then blown
into 1 liter bottles and tested on a Mocon Oxtran Permeation
Testing unit for Oxygen permeation, using a two-day test period.
The results are shown in Table 3 below.
TABLE-US-00004 TABLE 3 Nylon Cobalt Oxygen Masterbatch OS Polyester
Masterbatch Permeation Rate Bottle (wt- %) (wt-%) (wt-%)
(cc/pkg/day) PET 0.063582 Control A 2.00 0.17 0.052851 B 0.30 0.50
0.011071 Ex. 10 2.00 0.30 0.17 0.000917
[0146] As illustrated by Table 3, the bottles of Example 10
including both MXD6 nylon and the OS polyester polymer of Example 9
demonstrated significantly more effective oxygen-scavenging than
bottles containing either component individually.
Example 11
Articles
[0147] Three masterbatch compositions were prepared using a
twin-screw extruder: (i) a cobalt masterbatch containing PET and
cobalt neodecanoate with a cobalt concentration of 5000-15000 ppm;
(ii) a nylon masterbatch containing 40-60 wt-% MXD6 nylon
(Mitsibushi) and 60-40 wt-% PET; and (iii) a OS polyester
masterbatch containing 5-15 wt-% of the oxygen-scavenging polyester
of Example 9 and 85-95 wt-% of PET. Monolayer 38 gram, 625 ml, PET
beverage bottles with a 40 mm finish were blowmolded from preforms
containing varying levels of the oxygen-scavenging polyester
polymer of Example 9 and MXD6 nylon. The following bottles were
prepared: [0148] PET control bottles (i.e., 100 wt-% PET), [0149]
PET bottles containing 0.3 wt-% of the OS polyester of Example 9
and 0.25 wt-% of cobalt masterbatch, [0150] 11A: PET bottles
containing 0.3 wt-% of the OS polyester of Example 9, 2 wt-% of the
MXD6 masterbatch, and 0.25 wt-% of the cobalt masterbatch; and
[0151] 11B: PET bottles containing 3 wt-% of the masterbatch of the
OS polyester of Example 9, 2 wt-% of the MXD6 masterbatch, and 0.25
wt-% of the cobalt masterbatch. The bottles were filled with
nitrogen-sparged water and sealed with a glass slide using an epoxy
adhesive. The oxygen concentration inside the sealed bottles stored
under ambient conditions was measured over time using an OXYSENSE
oxygen testing unit. The data is reported below in Table 4.
TABLE-US-00005 [0151] TABLE 4 Total Parts Oxygen (in parts per
billion) Example 11 11A: Bottles 11B: Bottles PET Control PET
Bottle with Ex. 9 OS with Ex. 9 OS Bottle (100 with Ex. 9 Polyester
+ Polyester + Days wt-% PET) OS Polyester MXD6 MXD6 0 198 142 137
294 1 291 164.5 58.5 137 4 416 83.5 37.5 36 12 855 95.5 38 37 15
1032.5 132.5 38 36.5 18 1180 196 37 36.5 21 1328 262.5 37 36.5 28
1646.5 427.5 35 34.5 35 1984.5 633.5 27 26.5 42 2292.5 823.5 36
35.5 50 2639 1060.5 31 31.5 56 2818.5 1198 26.5 27 64 3208 1435.5
31.5 31.5 70 3271.5 1589.5 31 31.5 77 4036 2318 27.5 31
[0152] As shown in the data of Table 4, the concentration of oxygen
present in the sealed PET control bottle steadily increased from
days 0 to 77. The oxygen concentration of the PET bottle containing
the oxygen-scavenging polymer of Example 9 without any MXD6 nylon
initially decreased between days 1 and 4, but then increased
between days 12 and 77. In contrast, the concentration of oxygen
present in bottles 11A and 11B of Example 11 rapidly decreased
between days 0 and 4 and remained at a low level out to day 77.
Thus, the bottles of Example 11 containing both the
bicyclic-functional polyester of Example 9 and MXD6 nylon exhibited
a superior oxygen-scavenging profile.
[0153] Table 4 above does not include a PET bottle containing MXD6
nylon as the only scavenging polymer because such tests were not
run. However, in a separate set of bottle experiments, the
concentration of oxygen present in sealed PET bottles (monolayer 38
gram, 500 ml beverage bottles with a 38 mm finish) made from a MXD6
nylon/PET masterbatch and a cobalt/PET masterbatch (similar to that
used above for Table 4) were analyzed using an Orbisphere oxygen
sensor system. The bottles did not include any oxygen scavenging
polymers in addition to the MXD6 nylon. The data for PET bottles
containing varying levels of the MXD6 nylon/PET masterbatch is
provided below in Table 5.
TABLE-US-00006 TABLE 5 Total Parts Oxygen (in parts per billion)
PET Bottles PET Bottles PET Bottles including including including
PET Control 2 wt-% 3 wt-% 4 wt-% Bottles (100 MXD6/PET MXD6/PET
MXD6/PET days wt-% PET) masterbatch masterbatch masterbatch 0* 0.2
0.2 0.2 0.2 8 0.86 0.58 0.28 0.19 43 2.75 1.50 0.69 0.31 70 3.96
2.23 0.94 0.60 135 5.53 2.68 1.15 0.57 171 6.45 3.01 1.08 0.39
*Estimated.
[0154] As illustrated by Table 5, the PET bottles containing
varying levels of MXD6 nylon each exhibited a "lag" in
oxygen-scavenging. In contrast, the PET bottles of Example 11 that
included 4 wt-% of the MXD6 nylon/PET masterbatch in combination
with the OS polyester polymer of Example 9 did not exhibit any such
lag.
[0155] The complete disclosure of all patents, patent applications,
and publications, and electronically available material cited
herein are incorporated by reference. The foregoing detailed
description and examples have been given for clarity of
understanding only. No unnecessary limitations are to be understood
therefrom. The invention is not limited to the exact details shown
and described, for variations obvious to one skilled in the art
will be included within the invention defined by the claims.
* * * * *