U.S. patent application number 10/677582 was filed with the patent office on 2005-04-07 for oxygen scavenger for low moisture environment and methods of using the same.
Invention is credited to Powers, Thomas.
Application Number | 20050072958 10/677582 |
Document ID | / |
Family ID | 34393754 |
Filed Date | 2005-04-07 |
United States Patent
Application |
20050072958 |
Kind Code |
A1 |
Powers, Thomas |
April 7, 2005 |
Oxygen scavenger for low moisture environment and methods of using
the same
Abstract
An oxygen-absorbing composition, device, and method for oxygen
scavenging in a low moisture environment are provided. The present
invention provides an oxygen absorbing composition which includes
an oxygen reducing agent, water, a carrier, an electrolyte salt,
and a humectant salt, which may be the same as the electrolyte
salt, present in an amount sufficient to reduce the water activity
of the composition to below 0.6. Also included are methods of using
the composition.
Inventors: |
Powers, Thomas; (Mayville,
NY) |
Correspondence
Address: |
RATNERPRESTIA
P O BOX 980
VALLEY FORGE
PA
19482-0980
US
|
Family ID: |
34393754 |
Appl. No.: |
10/677582 |
Filed: |
October 2, 2003 |
Current U.S.
Class: |
252/188.28 |
Current CPC
Class: |
A23L 3/3436 20130101;
C09K 15/02 20130101; Y02E 60/32 20130101 |
Class at
Publication: |
252/188.28 |
International
Class: |
C09K 003/00 |
Claims
What is claimed:
1. An oxygen absorbing composition comprising: at least one oxygen
reducing agent; water; a carrier; an electrolyte salt; and a
humectant salt, which may be the same as the electrolyte salt,
present in an amount sufficient to reduce the water activity of the
composition to below 0.6.
2. The oxygen absorbing composition of claim 1 wherein the amount
of humectant salt and electrolyte salt combined is sufficient to
reduce the water activity within the composition to below 0.59.
3. The oxygen absorbing composition of claim 1 wherein the amount
of humectant salt and electrolyte salt combined is sufficient to
reduce the water activity within the composition to below 0.55.
4. The composition of claim 1 wherein the reducing agent is
selected from the group consisting of iron, copper, zinc, sulfides,
sulfites, ascorbic acid, salts of ascorbic acid, chlorine, iodine,
bromine, carotenoids, tocopherol, polyphenols, and combinations
thereof.
5. The composition of claim 1 wherein the reducing agent is 200
mesh iron powder.
6. The composition of claim 1 wherein the humectant salt is
selected from the group consisting of sodium chloride, calcium
chloride, lithium chloride, iodides, carbonates, sulfate salts, and
combinations thereof.
7. The composition of claim 1 wherein the electrolyte salt is
selected from the group consisting of sodium chloride, calcium
chloride, potassium iodide, lithium chloride, and combinations
thereof.
8. The composition of claim 1 wherein the carrier is selected from
the group consisting of silica, clay, cellulose, natural and
synthetic silicates, a gelling agent, and combinations thereof.
9. An oxygen scavenging composition comprising: 30-70 wt %
electrolytic iron; 10-40 wt % carrier; 10-20 wt % water; 1-10 wt %
sodium chloride; and 1-30 wt % humectant salt.
10. An oxygen scavenging composition comprising: 30-55 wt %
electrolytic iron; 25-37 wt % silica gel; 10-15 wt % water; 3-6 wt
% sodium chloride; and 3-6 wt % humectant salt.
11. A device for scavenging oxygen within a low-moisture container
comprising: an oxygen absorbing composition comprised of: an oxygen
reducing agent; water; a carrier; an electrolyte salt; and a
humectant salt, which may be the same as the electrolyte salt,
present in an amount sufficient to reduce the water activity of the
composition to below 0.6; and a barrier to enclose said oxygen
absorbing composition and retain said oxygen absorbing composition
within said low-moisture container, said barrier allowing the
passage of oxygen to said composition and limiting the escape of
moisture out of said composition.
12. The device of claim 11 wherein the barrier is comprised of a
material selected from the group consisting of polyethylene,
polypropylene, polyester, nylon, ionomer, and laminated
combinations thereof.
13. The device of claim 11 wherein the barrier is comprised of a
material selected from the group consisting of a linear low density
polyethylene laminate, a laminated film composite, and a laminated
film and paper composite.
14. The device of claim 11 wherein the barrier is selected from the
group consisting of a sachet, a canister, a self-adhesive laminate,
a label, and a capsule.
15. A method of making an oxygen absorbing composition for use in a
low-moisture environment comprising the steps of: (a) dissolving an
electrolyte salt and a humectant salt in water, wherein the
humectant salt may be the same as the electrolyte salt, and wherein
the humectant salt and electrolyte salt are present in sufficient
amount to reduce the water activity of the composition to below
0.6; (b) mixing the solution of step (a) with a carrier; (c)
blending the mixture of step (b) with at least one reducing agent;
and (d) placing the blend of step (c) within a barrier, the barrier
allowing the passage of oxygen to the blend and limiting the escape
of moisture away from the blend.
16. The method of claim 15 wherein the reducing agent is selected
from the group consisting of iron, copper, zinc, sulfides,
sulfites, ascorbic acid, salts of ascorbic acid, chlorine, iodine,
bromine, carotenoids, tocopherol, polyphenols, and combinations
thereof.
17. The method of claim 15 wherein the humectant salt is selected
from the group consisting of sodium chloride, calcium chloride,
lithium chloride, iodides, carbonates, phosphates and sulfate
salts.
18. The method of claim 15 wherein the electrolyte salt is selected
from the group consisting of sodium chloride, calcium chloride,
potassium iodide, lithium chloride, bromides, and combinations
thereof.
19. The method of claim 15 wherein the carrier is selected from the
group consisting of silica gel, clay, cellulose fiber, and
combinations thereof.
20. A method of storing moisture-sensitive, oxygen-sensitive
substances in a low-moisture, low-oxygen environment, said method
comprising: placing a moisture-sensitive, oxygen-sensitive
substance into an oxygen-permeable container having an environment
with an equilibrium relative humidity of less than 50%; and
disposing an oxygen-scavenging composition within said
oxygen-permeable container, said oxygen-scavenging composition
disposed within an oxygen-permeable barrier and having a water
activity less than 0.60.
21. The method of claim 20 wherein the oxygen-scavenging
composition is comprised of: 30-70 wt % electrolytic iron; 10-40 wt
% silica gel; 10-20 wt % water; 1-10 wt % sodium chloride; and 1-30
wt % humectant salt.
22. The method of claim 20 wherein the oxygen-permeable barrier is
comprised of a material selected from the group consisting of
polyethylene, polypropylene, polyester, nylon, ionomer, and
laminated combinations thereof.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to oxygen-absorbents, and more
specifically to oxygen-absorbing compositions, devices, and methods
of storage for low-moisture environments.
BACKGROUND OF THE INVENTION
[0002] Oxygen is typically detrimental to food and pharmaceuticals.
There are, therefore, many technologies in existence to reduce
oxygen in food, pharmaceutical, medical device, and diagnostic
product storage environments, such as plastic containers, pouches,
cases, bottles and the like. But the need to limit oxygen exposure
is not limited to just these applications. Many products can have
longer shelf-lifes if oxygen is diminished, including paints and
other consumer goods.
[0003] One technique that has recently been the subject of
development involves the placement of oxygen absorbing packages
into the product package to protect against spoilage, loss of
potency, or other loss of value due to oxidation of the product.
These packages themselves contain oxygen absorbers, or scavengers,
and are added into or constructed into sealed packages. The sealed
containers having the oxygen scavenging packages within them have
been used to lengthen shelf-life of many products. Some examples of
this include preserving oils from rancidity, foods from developing
mold and bacteria growth, pharmaceuticals from loss of potency,
sensitive diagnostic products from oxidation, electronics from
corrosion and archives and artifacts from yellowing and
embrittlement.
[0004] The typical oxygen absorber depends upon oxidation of iron
or similar metal to reduce oxygen. Other techniques include the use
of chemical or biochemical methods but these are typically limited
in application by relatively low capacity, low rate of reaction,
and higher cost.
[0005] Metal-based oxygen absorbers function by oxidizing the metal
while reducing oxygen to the oxide form. It is an electrolytic
reaction which requires moisture and an electrolyte in order to
proceed. This reaction occurs readily in a high water activity
environment such as A.sub.w=0.8-1.0, but slows considerably below
A.sub.w=0.8. This is fine for the storage and preservation of
products which tolerate a heightened moisture environment, but is
not acceptable where such is not the case.
[0006] An improved oxygen-absorbing composition or system would
allow for oxygen scavenging in a relatively low moisture
environment.
SUMMARY OF THE INVENTION
[0007] The present invention provides oxygen-absorbing
compositions, devices, and methods for oxygen scavenging in a low
moisture environment. Generally, the present invention provides an
oxygen absorbing composition comprising at least one oxygen
reducing agent, water, a carrier, an electrolyte salt(s), and a
humectant salt(s), which may be the same as the electrolyte salt,
present in an amount sufficient to reduce the water activity of the
composition to below 0.6.
[0008] More specifically, the present invention includes as one
embodiment an oxygen scavenging composition comprising 30-70 wt %
electrolytic iron, 10-40 wt % carrier (or stabilizer), 10-20 wt %
water, 1-10 wt % sodium chloride, and 1-30 wt % humectant salt. A
more preferred embodiment is an oxygen scavenging composition
comprising 30-55 wt % electrolytic iron, 25-37 wt % silica gel,
10-15 wt % water, 3-6 wt % sodium chloride, and 3-6 wt % humectant
salt.
[0009] The present invention also includes a device for scavenging
oxygen within a low-moisture container, the device comprising an
oxygen absorbing composition comprised of an oxygen reducing agent,
water, a carrier, an electrolyte salt, and a humectant salt, which
may be the same as the electrolyte salt, present in an amount
sufficient to reduce the water activity of the composition to below
0.6; and a barrier to enclose the oxygen absorbing composition and
retain the oxygen absorbing composition within the low-moisture
container. The barrier allows the passage of oxygen to the
composition and limits (or retards) the escape of moisture out of
the composition. When the moisture does equilibrate, the ERH of the
container will not exceed the ERH of the oxygen scavenging
composition itself.
[0010] Also included as a part of the present invention is a method
of making an oxygen absorbing composition for use in a low-moisture
environment comprising the steps of (a) dissolving an electrolyte
salt and a humectant salt in water, wherein the humectant salt may
be the same as the electrolyte salt, the salt(s) itself may be a
reducing agent, and wherein the humectant salt and electrolyte salt
are present in sufficient amount to reduce the water activity of
the composition to below 0.6; (b) mixing the solution of step (a)
with a carrier (where the carrier may have some water binding
capability); (c) blending the mixture of step (b) with at least one
reducing agent; and (d) placing the blend of step (c) within a
barrier, the barrier allowing the passage of oxygen to the blend
and limiting (or retarding) the escape of moisture away from the
blend.
[0011] Also included is a method of storing moisture-sensitive,
oxygen-sensitive substances in a low-moisture, low-oxygen
environment. The method comprises placing a moisture-sensitive,
oxygen-sensitive substance into an oxygen-permeable container
having an environment with an equilibrium relative humidity of less
than 50%; and disposing an oxygen-scavenging composition within the
oxygen-permeable container, the oxygen-scavenging composition
disposed within an oxygen-permeable barrier and having a water
activity less than 0.60.
BRIEF DESCRIPTION OF THE DRAWING
[0012] The FIGURE illustrates a device containing the composition
of the present invention to reduce oxygen content within a
container housing a dosage form pharmaceutical.
DETAILED DESCRIPTION OF THE INVENTION
[0013] The present invention provides compositions, devices, and
methods for storing moisture-sensitive, oxygen-sensitive substances
in a low-moisture, low-oxygen environment. One example of such a
use is shown in the FIGURE, which illustrates a container 100
housing a pharmaceutical product, in this case capsules 110.
Typical such containers would be made from any of a number of
materials, including polyethylene (both HDPE and LDPE),
polypropylene, polystyrene, and polycarbonate.
[0014] The container allows some oxygen to enter the space
surrounding pharmaceutical capsules 110, despite being made of a
material which generally resists oxygen passage. In such a case,
the oxygen which does manage to pass through the container wall
must be absorbed in order to prolong the useful life of
pharmaceutical capsules 110.
[0015] The FIGURE also shows the presence of one embodiment of the
present invention, namely sachet 120 which contains oxygen
absorbing composition 130. In instead of a sachet. The barrier
(e.g. sachet) is made of a material (described in more detail
below) which allows oxygen to pass through but limits water
passage. This oxygen permeability and water (non)permeability are
also defined in more detail below. Generally, and as noted above,
the oxygen absorbing composition needs a certain level of moisture
to adequately absorb oxygen, yet humid environments are undesirable
from the standpoint of the stored product (in this case capsules
110). The present invention thus has adequate water present in the
sachet, which water is generally restricted from leaving the
sachet. Moreover, oxygen enters the dry container environment,
passes through the barrier material into the sachet interior and is
absorbed within the oxygen scavenging composition, all while water
presence is generally limited to within the sachet. It is this
control of water activity between the container environment and
sachet environment which forms part of the invention in conjunction
with appropriate oxygen scavengers (described in more detail
below).
[0016] Water activity, typically represented by the variable,
A.sub.w, is an indicator of the free moisture content of a
substance, but is not simply the percent weight of water within a
substance. Often, the total moisture content of a substance is
defined as the percentage weight of water in relation to the dry
weight of the substance. This number is also different than the
water activity value.
[0017] Substances in which moisture can be present can be
classified in two categories: hygroscopic and non-hygroscopic.
Included among hygroscopic materials are salts, most metal oxides,
and many polymers. Hygroscopic substances may absorb water in
different ways. Depending on the absorption process, water is bound
to the product with more or less strength. Moisture content can
include both an immobilized part (e.g. water of hydration) and an
active part. Water activity A.sub.w (or equilibrium relative
humidity (ERH)) measures the vapor pressure generated by the
moisture present in a hygroscopic product (%
ERH=A.sub.w.times.100). Water activity reflects the active part of
moisture content or the part which, under normal circumstances, can
be exchanged between the substance and its environment. It is
essentially a measure of "available" water as opposed to "total"
water content.
[0018] The active part of moisture content and, therefore, water
activity, provides better information than the total moisture
content regarding the micro-biological, chemical and enzymatic
stability of perishable products such as food or pharmaceuticals.
Water activity can also be directly compared with the relative
humidity of the ambient air to prevent dimensional changes in a
product such as paper or photographic film, and to prevent
hygroscopic powders (powdered sugar, salt) from caking or turning
into a solid block.
[0019] Although a water activity of 0.3-0.5 would typically be
satisfactory for some drug compounds, others are stable only if the
equilibrium relative humidity (ERH) of the environment is 20% or
less (A.sub.w.ltoreq.0.20). The problem with such an environment,
however, is that oxygen scavengers need at least a minimal level of
water activity in order to absorb oxygen. Thus, the competing
forces of a dry environment which is necessary for the product to
exist, and a moist environment which the scavenger needs in order
to absorb oxygen, oppose each other to create a problem for one
wishing to absorb oxygen in a dry environment.
[0020] The present invention solves this problem by utilizing an
effective oxygen absorbing composition which has a self-contained
and limited water supply so that the composition can work in a
relatively low moisture environment. The composition itself is
contained within a package material that has barrier properties to
maintain the relatively low moisture environment outside of the
package. Thus, the present invention provides a system where the
oxygen scavenging package material holds the necessary moisture
within the package to support the oxygen scavenging reaction while
maintaining a relative humidity outside the package (but within the
container, in other words the environment outside the oxygen
scavenging package but inside the product container, such as a pill
bottle) at less than the A.sub.w of the oxygen absorbing formula
and below the level at which detrimental effects of moisture would
impact the container's contents (e.g. a pharmaceutical). More
specifically, a product which is otherwise stable at <60%
relative humidity can be protected from oxidation by this oxygen
absorber.
[0021] The combination of a scavenging agent and electrolyte with
water in a suitable carrier has been known as an oxygen absorbing
composition. The present invention, however, also contains a
humectant salt, which is used to bind moisture within the oxygen
absorbing composition such that water activity of the composition
remains high relative to the ERH of the environment outside of the
package which surrounds the stored product (e.g. pharmaceutical or
food). It is noted that over enough time (typically several months
or years) a steady state condition will be reached. By steady
state, it is meant that eventually the water activity inside the
package will essentially equilibrate with the relative humidity
outside of the package, and although oxygen absorption will still
occur within the package, moisture content within the container
will have effectively risen to detrimental levels, given enough
time. The important aspect of the present invention, however, is
that early in the term of storage (early part of the shelf-life),
the oxygen absorption is occurring readily in a low moisture
container. This is especially beneficial in the first few weeks of
storage as this is the time when a relatively high amount of oxygen
is present within the container as a result of typical packaging
conditions. Thus, after closure of the container following
packaging, oxygen is quickly removed from the container's inner
environment, despite there being a very dry environment within the
container. Heretofore, such dry environments meant poor oxygen
absorption.
[0022] Typical reducing agents used with the present invention
include iron, copper, zinc, sulfides, sulfites, ascorbic acid,
salts of ascorbic acid, chlorine, iodine, bromine, carotenoids,
tocopherol, polyphenols, and combinations thereof. Preferred among
these is iron, and in particular a 200 mesh electrolytic iron
powder.
[0023] Carriers used with the present invention include silica (and
silica gel), clay, cellulose, natural and synthetic silicates, a
gelling agent, and combinations thereof.
[0024] Humectant salts used with the present invention include
sodium chloride, calcium chloride, lithium chloride, iodides,
carbonates, sulfate salts, and combinations thereof. Preferred
among these are sodium chloride and calcium chloride.
[0025] As noted above, the package material should have limited
water permeability but relatively high oxygen permeability. By
limited water permeability, it is meant that the escape of water
from the package be adequately limited or retarded so that adequate
moisture is present within the package to support oxygen
absorption. In general, as long as the oxygen permeability exceeds
that of water permeability, the barrier will work in accordance
with the present invention. Such materials can be quantitatively
defined as any which has a vapor transmission rate preferably no
greater than 0.5 g/100 in.sup.2/day at 100.degree. F., 90% RH, and
more preferably no greater than 0.1 g/100 in.sup.2/day at
100.degree. F., 90% RH. By relatively high oxygen permeability, it
is meant that the oxygen transmission rate should be at least 20
cc/100 in.sup.2/day at 73.degree. F. 50% RH, and preferably greater
than 50 cc/100 in.sup.2/day at 73.degree. F. 50% RH.
[0026] Preferred among these materials are laminated films or film
and paper composite structures. More preferred are laminates of
water-oil-grease resistant paper and linear low density
polyethylene (LLDPE) film. Included among preferred embodiments are
linear low density polyethylene films laminated to an Aclar film
(Aclar is a fluorine-containing plastic in sheet form and is a
trademark of Honeywell International Inc.). In such a film, the
LLDPE acts as both the seal and semi-permeable layer. Generally,
however, appropriate barrier materials would include materials
comprising polyethylene, polypropylene, polyester, nylon, ionomer,
and laminated combinations thereof, so long as they exhibit the
permeabilities defined above.
[0027] The barrier itself could take many forms, including sachets,
canisters, capsules, self-adhesive laminates, and labels. The
self-adhesive laminate could be used in a variety of applications,
including as a backing layer for a blister-pack application or as a
label for a food or pharmaceutical package.
[0028] The present invention includes the use of a device for
scavenging oxygen within a low-moisture container. The device is
comprised of an oxygen absorbing composition and a barrier to
enclose the oxygen absorbing composition and retain the oxygen
absorbing composition within the low-moisture container. The oxygen
composition comprises at least one oxygen reducing agent, water, a
carrier, an electrolyte salt, and a humectant salt, which may be
the same as the electrolyte salt, present in an amount sufficient
to reduce the water activity of the composition to below 0.6. The
barrier is selected such that it allows the passage of oxygen to
the composition and limits the escape of moisture out of the
composition.
[0029] Also included as a part of the present invention is a method
of making an oxygen absorbing composition for use in a low-moisture
environment. Generally, the method comprises the steps of: (a)
dissolving an electrolyte salt and a humectant salt in water,
wherein the humectant salt may be the same as the electrolyte salt,
and wherein the humectant salt and electrolyte salt are present in
sufficient amount to reduce the water activity of the composition
to below 0.6; (b) mixing the solution of step (a) with a carrier;
(c) blending the mixture of step (b) with at least one reducing
agent; and (d) placing the blend of step (c) within a barrier, the
barrier allowing the passage of oxygen to the blend and limiting
the escape of moisture away from the blend. The components used in
this method are as defined above.
[0030] Finally, the present invention also includes a method of
storing moisture-sensitive, oxygen-sensitive substances in a
low-moisture, low-oxygen environment. The method comprises the
steps of placing a moisture-sensitive, oxygen-sensitive substance
into an oxygen-permeable container having an environment with an
equilibrium relative humidity of less than 50%; and disposing an
oxygen-scavenging composition within said oxygen-permeable
container, said oxygen-scavenging composition disposed within an
oxygen-permeable barrier and having a water activity less than
0.60. As above, the components used in this method are as defined
above.
[0031] The following examples demonstrate the effectiveness of the
invention.
EXAMPLE 1
[0032] An oxygen-absorbing blend was prepared by combining 20 grams
(g) sodium chloride (NaCl), 10 g ascorbic acid
(C.sub.6H.sub.8O.sub.6), and 10 g sodium ascorbate
(Na--C.sub.6H.sub.7O.sub.6) with 60 g of water. This mixture was
combined 45/55 with silica gel. The blend was found to have an ERH
of 59%. Seventy-five one hundredths of a gram (0.75 g) of this
blend was mixed with 0.75 g of 200 mesh electrolytic iron and
sealed within a semipermeable sachet.
[0033] The sachet was placed within a high barrier test container
with a measured amount of air and was found to absorb over 200 cc
of oxygen in 60 days in a dry atmosphere. During this time the ERH
within the test container did not exceed 51%.
EXAMPLE 2
[0034] An oxygen absorbing blend was prepared by combining 10 g
sodium chloride and 20 g calcium chloride with 70 g of water. This
mixture was combined 45/55 with silica gel. The blend was found to
have an ERH of 48.3%.
[0035] Two grams (2 g) of this blend was mixed with 1 g of 200 mesh
electrolytic iron and sealed within a semipermeable sachet. The
sachet was a laminate of water-oil-grease resistant paper and a
linear low density polyethylene film. The film had a water vapor
transfer rate of 0.456 g/100 in.sup.2/day @1100.degree. F., 90%
r.h. and an oxygen transfer rate of 61.8 cc/100 in.sup.2/day @
73.degree. F., 50% r.h.
[0036] The sachet was placed within a high barrier test container
with 500 cc of air and was found to absorb over 37 cc of oxygen in
66 days in a dry atmosphere.
EXAMPLE 3
[0037] An oxygen absorbing blend was prepared by combining 10.4 g
sodium chloride, 20.8 g calcium chloride, and 68.8 g of water. This
mixture was combined 45/55 with silica gel.
[0038] 1.2 g of this blend was mixed with 1.2 g of 200 mesh
electrolytic iron, combined with 0.1 g of a 50% dispersion of a
binder (polyvinyl pyrollidone) and sealed within a semipermeable
canister. The canister was constructed of a cylindrical
polyethylene body and a film end material. The end material had a
water vapor transfer rate of 0.008 g/100 in.sup.2/day and an oxygen
transfer rate of 45 cc/100 in.sup.2/day @ 73.degree. F., 50%
r.h.
[0039] The canister was placed within a high barrier test container
with a measured amount of air and was found to absorb oxygen at the
rate of 0.85 cc/day. During this time the ERH within the test
container did not exceed 56.9%. The same formulation ceased to
absorb after 13 days in a permeable sachet.
EXAMPLE 4
[0040] An oxygen absorbing blend was prepared by combining 10 g
sodium chloride, 40 g potassium iodide, and 50 g of water. This
mixture was combined 45/55 with silica gel. The blend was found to
have an ERH of 43.8%.
[0041] Two grams (2 g) of this blend was mixed with 1 g of 200 mesh
electrolytic iron and sealed within a semipermeable sachet. The
sachet was a laminate of water-oil-grease resistant paper and a
linear low density polyethylene film. The film had a water vapor
transfer rate of 0.456 g/100 in.sup.2/day @1100.degree. F., 90%
r.h. and an oxygen transfer rate of 61.8 cc/100 in.sup.2/day @
73.degree. F., 50% r.h.
[0042] The sachet was placed within a high barrier test container
with a measured amount of air and was found to absorb over 97 cc of
oxygen in 52 days in a dry atmosphere.
[0043] The following table summarizes the above examples. The
electrolytic iron was 200 mesh in each case.
1 EXAMPLE Composition Performance 1 50 wt % electrolytic iron This
composition was 27.5 wt % silica gel placed in semi-permeable 13.5
wt % water sachet and absorbed over 4.5 wt % NaCl 200 cc of oxygen
in 60 days 2.25 wt % Na ascorbate in a dry atmosphere. 2.25 wt %
Ascorbic acid During this time the ERH within the test container
did not exceed 51%. 2 50 wt % electrolytic iron This composition
was 27.5 wt % silica gel placed in semi-permeable 15.75 wt % water
sachet and absorbed over 2.25 wt % NaCl 37 cc of oxygen in 66 days
4.50 wt % CaCl.sub.2 in a dry atmosphere. 3 48 wt % electrolytic
iron This composition was 26.1 wt % silica gel placed in
semi-permeable 14.9 wt % water canister and was found to 2.34 wt %
NaCl absorb oxygen at the rate of 4.68 wt % CaCl2 0.85 cc/day in a
dry 3.98 wt % binder atmosphere. During this time the ERH within
the test container did not exceed 56.9%. 4 33.33 wt % electrolytic
iron This composition was 36.67 wt % silica gel placed in
selectively- 15.0 wt % water permeable sachet and 3.0 wt % NaCl
absorbed over 97 cc of 12 wt % KI oxygen in 52 days in a dry
atmosphere.
[0044] Although the invention is illustrated and described herein
with reference to specific embodiments, the invention is not
intended to be limited to the details shown. Rather, various
modifications may be made in the details within the scope and range
of equivalents of the claims and without departing from the
invention.
* * * * *