U.S. patent application number 16/717319 was filed with the patent office on 2020-06-18 for humidity control slurries, apparatuses, and methods of making same.
This patent application is currently assigned to Boveda, Inc.. The applicant listed for this patent is Boveda, Inc.. Invention is credited to Jonathan W. DeVries, Robert L. Esse, Tina O'Shea, Brian Rice.
Application Number | 20200188845 16/717319 |
Document ID | / |
Family ID | 71071080 |
Filed Date | 2020-06-18 |
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United States Patent
Application |
20200188845 |
Kind Code |
A1 |
O'Shea; Tina ; et
al. |
June 18, 2020 |
Humidity Control Slurries, Apparatuses, and Methods of Making
Same
Abstract
Slurries and methods of making slurries for modifying and
extending relative humidity control ranges. The slurries may
include a saturated aqueous salt and one or more other reagents
selected to provide a controlled modifiable narrow range of
relative humidity. The saturated aqueous salt may be one or more of
sodium chloride, potassium chloride, potassium citrate, sodium
formate, and/or magnesium chloride, and the one or more other
reagents may be one or more of a lactate salt, glycerol, and/or an
acetate salt, for example.
Inventors: |
O'Shea; Tina; (Minnetonka,
MN) ; Esse; Robert L.; (Minnetonka, MN) ;
DeVries; Jonathan W.; (Minnetonka, MN) ; Rice;
Brian; (Minnetonka, MN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Boveda, Inc. |
Minnetonka |
MN |
US |
|
|
Assignee: |
Boveda, Inc.
Minnetonka
MN
|
Family ID: |
71071080 |
Appl. No.: |
16/717319 |
Filed: |
December 17, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62780676 |
Dec 17, 2018 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B01D 2259/4525 20130101;
B01D 53/28 20130101; B65D 81/268 20130101; B01D 2259/126
20130101 |
International
Class: |
B01D 53/28 20060101
B01D053/28; B65D 81/26 20060101 B65D081/26 |
Claims
1. A slurry for modifying and extending relative humidity control
ranges, the slurry comprising: a saturated aqueous salt; and one or
more other reagents; wherein the slurry provides a controlled
modifiable narrow range of relative humidity.
2. The slurry of claim 1, wherein the aqueous salt and the select
other reagents are food grade per Foods Chemicals Codex (FCC).
3. The slurry of claim 1, wherein the slurry is substantially
odorless.
4. The slurry of claim 1, wherein large crystals do not form in the
slurry during normal use of the slurry.
5. The slurry of claim 1, wherein the saturated aqueous salt is
sodium chloride, potassium chloride, potassium citrate, sodium
formate, or magnesium chloride.
6. The slurry of claim 1, wherein the one or more reagents
comprises a lactate salt. The slurry of claim 1, wherein the one or
more reagents comprises glycerol.
8. The slurry of claim 1, wherein the one or more reagents
comprises an acetate salt.
9. The slurry in claim 1 wherein the one or more reagents comprises
a food-grade optically and/or UV active additive.
10. The slurry of claim 1, where in the select reagent wherein the
one or more reagents comprises glycerol, the slurry further
comprising a thickening agent.
11. The slurry of claim 1 wherein select reagents may be added as
combinations.
12. The slurry of claim 1, wherein an amount of excess water
present ranges from 0% of the slurry concentration level of the
other components of the mixture to the water concentration at the
maximum humidity control point wherein saturation no longer
exists.
13. The slurry of claim 1, wherein the slurry comprises 0 to 2% of
a food grade gum providing viscosity control.
14. The slurry of claim 1 wherein the additive concentration
exceeds the salt concentration.
15. The slurry of claim 1 wherein the salt solution is not a
saturated solution.
16. The slurry of claim 1 wherein the slurry does not lose its
self-indicating property with regard to need for replacement.
17. A slurry for modifying and extending relative humidity control
ranges, the slurry comprising: a saturated aqueous salt comprising
one or more of sodium chloride, potassium chloride, potassium
citrate, sodium formate, and/or magnesium chloride; and one or more
other reagents comprising a lactate salt, glycerol, and/or an
acetate salt; wherein the slurry provides a controlled modifiable
narrow range of relative humidity.
18. The slurry of claim 17 further comprising up to 2% of a food
grade gum.
19. A method of making a slurry for modifying and extending
relative humidity control ranges, the method comprising: combining
a saturated aqueous salt and one or more other reagents; wherein
the slurry provides a controlled modifiable narrow range of
relative humidity.
20. The method of claim 19 wherein the other reagents comprise
lactate salt, glycerol, and/or an acetate salt.
Description
FIELD OF THE INVENTION
[0001] The present disclosure relates to novel and advantageous
systems and methods for modifying and extending relative humidity
control ranges using a device or system to maintain the relative
humidity in a closed environment. More particularly, the present
disclosure relates to novel and advantageous systems and methods to
modify and extend relative humidity control ranges in a closed
environment using a slurry comprising a saturated salt and an
additive.
BACKGROUND OF THE INVENTION
[0002] The background description provided herein is for the
purpose of generally presenting the context of the disclosure. Work
of the presently named inventors, to the extent it is described in
this background section, as well as aspects of the description that
may not otherwise qualify as prior art at the time of the filing,
are neither expressly nor impliedly admitted as prior art against
the present disclosure.
[0003] There is a need to keep pharmaceutical, health care,
electronics, food, plant materials, tobacco products, and
instruments, for example, at a constant and regulated moisture and
relative humidity level when they are stored in a container
assembly.
[0004] In order to keep contents in an optimized state, controlling
relative humidity at a specified level is preferred and/or
necessary. The desired humidity or predetermined humidity to
maintain product optimization (e.g. freshness, usefulness,
minimization of damage or decay) is variable in that different
products may need to be maintained at differing respective optimum
relative humidities. For example, some products are able to
maintain freshness when kept dry or at zero or relatively close to
zero relative humidity ("RH") and other products maintain freshness
when maintained at a relatively high level of humidity.
[0005] Embodiments of the present disclosure address the
maintenance of a predetermined relative humidity in a container
assembly to maintain the best quality of a product held in the
container assembly, which may be a pharmaceutical product, a health
care product, an electronics component, a food product, a plant
material, a tobacco product or nearly any product that may benefit
from storage in a predetermined relative humidity environment.
[0006] For many packaged products, including packaged consumer
products, it is beneficial to maintain a particular moisture
content within the package containing the product. Some humidity
control devices are configured to help maintain a consistent
relative humidity of the space within the product package that is
not taken up by the product itself. The RH may be maintained at a
level or range deemed optimum for the particular packaged product.
It is understood by those skilled in the art that the percent RH
("% RH") in the package will result in a percent by weight product
moisture content, but that the % RH in the space not taken up by
the product and the product percent moisture by weight are
different values that differ based on the characteristics of the
product and its propensity to absorb moisture from or desorb
moisture to the surrounding atmosphere. Many products may be
consumed, utilized, or accessed by a consumer over a period of
time, and maintaining a consistent RH may help preserve the life,
integrity, freshness, flavor, or other features of the product.
[0007] Many molds grow readily at water activity ("a.sub.w")
greater than 0.85 and some grow significantly at a.sub.w of 0.75.
Since it may be desirable to have as much water in the product to
maintain a pleasing texture yet prevent or control the amount of
mold growth, it may be important to maintain the a.sub.w of such
products in a narrow range just below the a.sub.w value at which
significant mold growth, if any, occurs.
[0008] While certain existing saturated salt humidity control
solutions are well suited to effectively control and maintain a
desired humidity level, there is an opportunity to improve upon
such solutions by providing a humidity control solution with the
properties of little to no odor and/or odor elimination, and/or
colorized to be visible or black light, and/or little to no large
crystal formation in the slurry/solution and/or extended absorption
and desorption at the desired relative humidity for example.
SUMMARY
[0009] Various embodiments include slurries for modifying and
extending relative humidity control ranges including a saturated
aqueous salt and one or more other reagents in which the slurry may
provide a controlled modifiable narrow range of relative humidity.
The aqueous salt and the select other reagents may be food grade
components per Foods Chemicals Codex (FCC). In some embodiments,
the slurry may be substantially odorless and/or large crystals may
not form in the slurry during normal use of the slurry. The
saturated aqueous salt may be one or more of sodium chloride,
potassium chloride, potassium citrate, sodium formate, or magnesium
chloride. The one or more reagents may be a lactate salt, glycerol,
an acetate salt, and/or a food-grade optically and/or UV active
additive, for example. In some embodiments, the slurry may further
include a thickening agent such as a gum. In some embodiments, the
slurry may include glycerol and a thickening agent.
[0010] In some embodiments, the reagents may be added as
combinations. In some embodiments, an amount of excess water may be
present in ranges from 0% or 0.1% of the slurry concentration level
of the other components of the mixture to the water concentration
at the maximum humidity control point wherein saturation no longer
exists.
[0011] In some embodiments, the slurry may include 0 or 0.1% to 2%
of a food grade gum providing viscosity control. In some
embodiments, the additive concentration may exceed the salt
concentration. While in some embodiments the slurry may be a
saturated salt solution, in other embodiments the salt solution may
not be saturated. In some embodiments, the slurry may have a
self-indicating property with regard to need for replacement. The
slurry may not lose the self-indicating property, such as during
production or use of the slurry.
[0012] Various embodiments also include slurries for modifying and
extending relative humidity control ranges including a saturated
aqueous salt including one or more of sodium chloride, potassium
chloride, potassium citrate, sodium formate, and/or magnesium
chloride, and one or more other reagents comprising a lactate salt,
glycerol, and/or an acetate salt. The slurry may provide a
controlled modifiable narrow range of relative humidity. In some
embodiments, the slurry may include up to 2% of a food grade gum,
such as 0%-2%, or 0.1%-2%.
[0013] Various other embodiments also include methods of making
slurries for modifying and extending relative humidity control
ranges. In some embodiments, the method may include combining a
saturated aqueous salt and one or more other reagents wherein the
slurry provides a controlled modifiable narrow range of relative
humidity. The other reagents may include lactate salt, glycerol,
and/or an acetate salt, for example.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] While the specification concludes with claims particularly
pointing out and distinctly claiming the subject matter that is
regarded as forming the various embodiments of the present
disclosure, it is believed that the disclosure will be better
understood from the following description taken in conjunction with
the accompanying Figures, in which:
[0015] FIG. 1 illustrates water activity (a.sub.w) versus % water
for embodiments in accordance with Example 1.
[0016] FIG. 2 illustrates water activity (a.sub.w) versus % water
for a control mixture in Example 1.
[0017] FIG. 3 illustrates water activity (a.sub.w) versus % water
for embodiments in accordance with Example 2.
[0018] FIG. 4 illustrates water activity (a.sub.w) versus % water
for embodiments in accordance with Example 3.
[0019] FIG. 5 illustrates water activity (a.sub.w) versus % water
for a control mixture in Example 3.
[0020] FIG. 6 illustrates water activity (a.sub.w) versus % water
for embodiments in accordance with Example 4.
[0021] FIG. 7 illustrates water activity (a.sub.w) versus % water
for a control mixture in Example 4.
[0022] FIG. 8 illustrates water activity (a.sub.w) versus percent
weight transfer over time for embodiments (slurry/solution with
additive and control) in accordance with Example 4 when held in a
low relative humidity (RH) environment.
[0023] FIG. 9 illustrates water activity (a.sub.w) versus percent
weight transfer over time for embodiments (slurry/solution with
additive and control) in accordance with Example 4 when held in a
high relative humidity environment.
DETAILED SUMMARY OF THE INVENTION
[0024] This application claims priority to provisional application
No. 62/780,676 filed Dec. 17, 2018 and entitled Improved Humidity
Control Solution, Apparatus, and Method of Making Same, the entire
contents of which are hereby incorporated by reference.
[0025] The present disclosure relates to novel and advantageous
systems and methods for modifying and extending relative humidity
control such as targets and ranges of relative humidity, minimizing
odor, having color visible with visible or black light, and
minimizing large crystal formation (i.e. crystals larger than
typical table salt crystals) while not losing the system's
self-indicating properties with regard to need for replacement when
using a device or system to maintain the relative humidity in a
closed environment. More particularly, the present disclosure
relates to novel and advantageous systems and methods to modify and
extend relative humidity control ranges in a closed environment
using a slurry comprising a saturated salt and an additive in some
embodiments. The slurry may be referred to as a
moisture-controlling solution, a humidity control solution, a
humidity control agent, or a saturated salt humidity control
solution.
[0026] A slurry may be used in relative humidity (RH) control
devices or systems to maintain a desired humidity in a closed
environment, e.g. a sealed container that may be opened and then
resealed repeatedly for access to a product stored therein. The
slurries disclosed herein may alternatively be referred to as
humidity control solutions. The slurry may be provided in a
delivery vehicle to provide humidity control to a target
environment in a closed system that may include a product such that
it may be maintained at or near a specific RH.
[0027] In some embodiments, the slurry or humidity control
solutions/systems in accordance with the disclosure are introduced
into a delivery vehicle or container that is generally water vapor
permeable and liquid water impermeable. Such container may be
referred to as a relative humidity control device and may comprise,
for example, a polymeric film pouch having at least some walls
sufficiently permeable to permit migration of water vapor through
the film and yet thick and impervious enough to prevent the escape
of liquids. The control device or delivery vehicle may be used to
control humidity within a generally closed environment including
but not limited to, an enclosure such as a container with a
removable cap, such as a glass jar, for protecting the contents
stored therein.
[0028] In some embodiments, the slurry may be provided in pouches
formed from polymeric films that breathe in a manner such that they
will transport moisture vapor but will contain the solution without
leaking liquid. The water vapor transport, known as water vapor
transmission rate (WVTR) may be measured in terms of grams of water
passed per 100 square inches of material per 24 hours under
standard test conditions. The WVTR is a function of the type of
film used and the thickness of the film. The total moisture
transferred, is also dependent upon the area of film exposed to a
humidity control solution in a given application. It has been shown
that a WVTR of about 10 grams water per 100 square inches over 24
hours provides good results for a device in accordance with the
invention.
[0029] Packaging film materials that may be used in embodiments of
the present disclosure include polyvinylchloride, fibrous
polyethylene (TYVEK.TM.), cellophane, polycarbonate, thin
polyolefin, oriented polystyrene, polyfluorocarbon, or polyester
laminated onto a suitable substrate such as paper. A delivery
vehicle such as a pouch may comprise, for example, polyamide nylon
film, such as Capran.TM., styrene-butadiene copolymer such as
K-Resin.TM., cellulose acetate, polyethylene terephthalate
(Mylar.TM.) ethylene vinyl acetate, or ethylene vinyl alcohol.
[0030] As disclosed in U.S. Pat. No. 5,936,178, entitled Humidity
Control Device, and filed Jun. 10, 1997 and U.S. Pat. No,
6,921,026, entitled Preservation of Intermediate Moisture Foods by
Controlling Humidity and Inhibition of Mold Growth, filed Feb. 5,
2002, the contents of which are hereby incorporated by reference in
their entirety, the RH of closed environments can be stabilized by
the use of humidity control systems comprised of moisture permeable
pouches containing specific saturated salt slurry/solutions, for
example. The inventive slurry disclosed herein may be delivered in
the pouches, or types of pouches, disclosed in the aforementioned
patents, in some embodiments.
[0031] Alternatively, embodiments of the moisture-controlling
solution of the present disclosure may be provided in a dedicated
area of a container, such as a glass or plastic container, which
may hold a product. The container may have a dedicated space to
hold the moisture-controlling solution, such that the liquid may
not escape the dedicated space, but water vapor may move into and
out of the dedicated space. It will be understood that while the
above methods are disclosed and within the scope of the invention,
still other delivery methods are within the spirit and scope of the
present disclosure.
[0032] As discussed above, the present disclosure relates to a
relative humidity (RH) control device(s) or a system(s) for use in
maintaining a desired humidity in a closed environment, e.g. a
sealed container that may be opened and reclosed at intervals.
Saturated salt-based RH devices have proven effective to control
the relative humidity in a closed environment, such as those
disclosed in U.S. Pat. No. 6,921,026, which is incorporated herein
in its entirety.
[0033] Embodiments of the devices or systems described herein are
designed to extend or modify the controlled relative humidity range
and/or capacity beyond those salt-based devices described, for
example, in U.S. Pat. No. 6,921,026. Embodiments of humidity
control solutions of the present disclosure may include the
advantageous properties of being odorless or substantially odorless
and/or colored to be visible by light such as visible light and
black light, and/or the property of preventing or substantially
limiting large crystal growth within the solution. Thus,
embodiments of the present disclosure may maintain a soft gel-like
texture throughout the device's useful life, or a substantial part
thereof, but still indicate the need for replenishment by
stiffening (hardening) of the gel-like texture.
[0034] Further, embodiments of the present disclosure may maintain
the desired relative humidity for a longer period of time than
existing humidity control solutions, and/or may emit or absorb
available water more quickly than existing humidity-control
systems, which allows the target environment to reach and maintain
the desired relative humidity faster. One reason for this is that
water uptake to or release from a device using the embodiments
described herein (for the humidity control slurry/solution) that
does not include or form large crystals has a more rapid uptake
rate than when large crystals are present due to crystal formation
and dissolution times.
[0035] These advantages may be achieved by embodiments of the
present disclosure by providing in a delivery vehicle a humidity
control solution that includes an aqueous saturated salt solution,
a thickening agent, and compatible specific compounds that extend
the controlled relative humidity range provided by the saturated
salt itself. It will be understood that other embodiments may
include additional additives.
[0036] The aqueous saturated salt slurry/solution may include
sodium formate, potassium citrate, or magnesium chloride for
example.
[0037] The thickening agent included in embodiments of the present
disclosure may include a food grade gum, such as xanthan gum, that
may be pre-hydrated with warm water in some embodiments. In other
embodiments, thickening agents may include hydroxyethylcellulose
(Natrosol.TM.), alumina (Aeroxide.TM.), or fumed silica
(Aerosil.TM.) for example. These thickening agents have a high
molecular weight and may be added in low concentrations so that
they exert only a minimal effect on the relative humidity control
of the device yet substantially increase the viscosity of the
solution. In some embodiments, the slurry may comprise
approximately 0 to 2% food grade gum, or other thickening agent,
for viscosity control, though it will be understood that in other
embodiments, more or less thickening agent may be included in the
humidity control solution.
[0038] The compatible specific compounds that extend the controlled
relative humidity range provided by the saturated salt itself may
include, for example, glycerol, potassium acetate, and/or sodium
lactate.
[0039] In addition, a food-grade additive that is optically and/or
UV active to be visible in visible or black light, for example, may
be added to any of the slurries/solutions illustrated in the
embodiments described herein and/or any of the examples below at a
level sufficient for the slurry/solution to be visible by an
observer in visible light or black light, for example. This
additive can be one or a combination of additives selected, for
example, from the group consisting of riboflavin, xanthene,
erythrosine, tartrazine, FD&C Blue #1 or their derivatives or
other food grade colors that are optically and/or UV active.
Addition of the optically and/or UV active additive may allow for
decorative coloring of the saturated salt slurry/solution, may be
used for a visual determination of slurry/solution homogeneity, may
be used to visualize the presence of defects such as packaging
leaks during the course of manufacturing and use of the humidity
control device, and/or other situations wherein visualization aids
in either the manufacturing or use of the humidity control
slurry/solution, or other circumstances.
[0040] Generally, in some embodiments, warm water may be mixed with
a food grade gum until the gum is hydrated. A first additive may be
added to the hydrated gum and agitated until the resultant first
mixture is homogenous, where the first additive may be a compatible
specific compound that adjusts the target relative humidity or
extends the controlled relative humidity range provided by the
saturating salt. A second additive may be added to the first
mixture and mixed until a homogenous slurry is created, wherein the
second additive may be a specific compound for relative humidity
target or relative humidity range or may be a salt in sufficient
quantity to create an aqueous saturated salt solution. In some
embodiments, the amount of water present in the homogenous slurry
can range from 0% concentration of the slurry/solution to the
maximum water level wherein salt saturation no longer exists.
[0041] The resultant humidity control solution may be dispensed
into a container which has a water vapor transmission rate of
approximately 10 grams/100 square inches/24 hours under standard
test conditions, or greater, in some embodiments. It will be
understood that other WVTRs may be achieved using the humidity
control solution of the present disclosure depending on the
container that is used.
[0042] The quantity of humidity control material or agent provided
within the container may vary based on desired RH control capacity,
size of product package or container assembly, and/or other
factors.
[0043] The following presents a simplified summary of one or more
embodiments of the present disclosure in order to provide a basic
understanding of such embodiments. This summary is not an extensive
overview of all contemplated embodiments and is intended to neither
identify key or critical elements of all embodiments, nor delineate
the scope of any or all embodiments.
[0044] The quantity of humidity control material or agent provided
within the container may vary based on desired RH control capacity,
size of product package or container assembly, and/or other
factors. The quantity of humidity control agent may vary from, for
example, less than one (1) gram to more than ten (10) grams of
material for each container assembly. For example, in some
embodiments the quantity of control agent may be 20 g, 25 g, 30 g,
60 g, or more depending on the need. It may be advantageous to
achieve a workable balance between the "footprint" of the humidity
control agent and its thickness. A larger footprint, while reducing
thickness, may increase a width and length of the container
assembly and thus require different volume and sizes.
[0045] The humidity control agent may allow for one-way or two-way
humidity control in some embodiments. That is, the humidity control
agent may be configured to remove moisture from the air and/or to
add moisture to the air within a storage cavity or container. In
some embodiments, one or more additives may be combined with the
humidity control agent, including but not limited to the additives
described in U.S. Pat. Nos. 9,750,811 and/or 5,936,178. For
example, some additives may be used to increase or otherwise
control viscosity levels of the humidity control agent or other
features of the humidity control agent, as may be desirable for the
designer or user.
WORKING EXAMPLES
Example 1
[0046] In one embodiment, 100 grams of water are mixed with 0.7 to
1.3 grams of xanthan gum until the gum is hydrated, and
approximately 36 to 70 grams of glycerol are added with stirring
until the mixture is substantially homogeneous. Approximately 82 to
158 grams of sodium formate are added and the mixing is continued
until the resultant slurry is substantially homogeneous to form a
saturated salt slurry/solution mixture.
[0047] The resulting saturated salt slurry/solution mixture
exhibits a water activity (a.sub.w) of approximately 0.49+/-0.05
for water content from approximately 12.3% to 43.3% and an a.sub.w
of approximately 0.49+/-0.15 for water content from approximately
9.8% to 53.5% when tested against low and high humidity
environments, respectively. FIG. 1 illustrates water activity
(a.sub.w) versus % water for embodiments in accordance with Example
1.
[0048] FIG. 2 illustrates water activity (a.sub.w) versus % water
for a control mixture. In comparison, a control mixture of 100
grams of water and 100 to 500 grams of sodium formate containing no
glycerol, exhibits a water activity (a.sub.w) of 0.59+/-0.05 range
of relative humidity control for water content from 9.0% to 55.5%
and an a.sub.w of approximately 0.59+/-0.15 for water content from
approximately 0.0% to 58% when tested against low and high humidity
environments, respectively.
[0049] The saturated salt slurry/solution in this example exhibits
no odor and no crystals larger than typical table salt crystals
form upon repeated cycling of moisture content within the operative
relative humidity range.
[0050] In this example, comparing the saturated salt
slurry/solution, with and without the additive clearly shows that
the target relative humidity provided by the saturated salt slurry
can be modified with addition of an additive.
Example 2
[0051] In another embodiment, a mixture of 100 grams of water is
mixed with approximately 0.7 to 1.4 grams of xanthan gum until the
gum is hydrated. Approximately 41 to 84 grams of 60% sodium lactate
solution are added with continued mixing until homogeneous,
followed by the addition of approximately 83 to 165 grams of sodium
formate with continued mixing until the slurry is homogenous to
form a saturated salt slurry/solution mixture.
[0052] The resulting saturated salt slurry/solution mixture
exhibits a water activity (a.sub.w) of approximately 0.49+/-0.05
for water content from approximately 21.8% to 47.6% and an a.sub.w
of approximately 0.49+/-0.15 for water content from approximately
11.0% to 55.0% when tested against low and high humidity
environments respectively. FIG. 3 illustrates water activity
(a.sub.w) versus % water for embodiments in accordance with Example
2.
[0053] This compares to a control mixture of 100 grams of water and
100 to 500 grams of sodium formate containing no sodium lactate
which exhibits a water activity (a.sub.w) of 0.59+/-0.05 range of
relative humidity control for water content from 9.0% to 55.5% The
saturated salt slurry/solution in this example exhibits a mild,
non-offensive, odor and crystals larger than typical table salt
crystals form only upon extended repeated cycling of moisture
content within the operative relative humidity range. This example
demonstrates that multiple additives, properly chosen, are
available to modify the relative humidity target of the mixture
while the mass of water available for controlling to the relative
humidity target remains approximately the same.
Example 3
[0054] In another embodiment, 100 grams of water are mixed with
approximately 0.8 to 2.7 grams of hydroxyethylcellulose until the
gum is hydrated, and approximately 6.5 to 7.5 grams of glycerol are
added with stirring until the mixture is substantially homogeneous.
Approximately 350 to 500 grams of magnesium chloride are added and
the mixing is continued until the resultant slurry is substantially
homogeneous to form a saturated salt slurry/solution mixture. The
resulting saturated salt slurry/solution mixture exhibits a water
activity (a.sub.w) of approximately 0.32+/-0.01 for water content
from approximately 8.3% to 22.6% when tested against low and high
humidity environments, respectively. FIG. 4 illustrates water
activity (a.sub.w) versus % water for embodiments in accordance
with Example 3.
[0055] For comparison, a control mixture of 100 grams of water and
approximately 350 to 500 grams of magnesium chloride with no
glycerol is prepared. FIG. 5 illustrates water activity (a.sub.w)
versus % water for the control mixture which contains no glycerol
and exhibits a water activity (a.sub.w) of 0.32+/-0.01 range of
relative humidity control for water content from approximately
14.7% to 22.6%.
Example 4
[0056] In another embodiment, 100 grams of water are mixed with 0.7
to 1.3 grams of xanthan gum until the gum is hydrated, and
approximately 1.25 to 2.5 grams of glycerol are added with stirring
until the mixture is substantially homogeneous. Approximately 168
to 900 grams of potassium citrate are added, and the mixing is
continued until the resultant slurry is substantially homogeneous
to form a saturated salt slurry/solution mixture. The resulting
saturated salt slurry/solution mixture exhibits a water activity
(a.sub.w) of approximately 0.62+/-0.05 for water content from
approximately 6.6% to 38.3% and an a.sub.w of approximately
0.62+/-0.15 for water content from approximately 0% to 50% when
tested against low and high humidity environments, respectively.
FIG. 6 illustrates water activity (a.sub.w) versus % water for
embodiments in accordance with Example 6. The resulting saturated
salt slurry/solution exhibits no odor and does not form large
crystals upon repeated recycling between high and low humidity
environments.
[0057] For comparison, a control mixture of 100 grams of water and
168 to 900 grams of potassium citrate with no glycerol is prepared.
FIG. 7 illustrates water activity (a.sub.w) versus % water for the
control mixture which contains no glycerol, exhibits a water
activity (a.sub.w) of 0.62+/-0.05 range of relative humidity
control for water content from 8.2% to 38.5% and an a.sub.w of
approximately 0.62+/-0.15 for water content from approximately 0%
to 48%. This example illustrates that using an additive increases
the water gain or loss range within the target RH range.
Example 5
[0058] FIG. 8 illustrates water activity (a.sub.w) verses % weight
transfer when the slurries/solutions of Example 4 are placed in a
low humidity environment, such as a relative humidity of
approximately 10%. The days indicated on the x axis for each set of
data represents the same calendar date. Thus, in FIG. 8, the data
point at day 6 shows that for the formula with the additive (black
bar for a.sub.w, and the light grey line for % weight transfer) due
to water transfer from the saturated salt slurry/solution to the
surrounding low relative humidity atmosphere) a.sub.w is 0.62 and
weight transfer is 15%. By comparison, the saturated salt
slurry/solution without additive is shown as a grey bar for the
same day/date with an a.sub.w of 0.62 and a % weight transfer of
8.7% shown as the black line. Alternatively assessing the weight
transfer from a time perspective in this example, it takes 6 days
for the saturated salt slurry/solution with additive of example 4
to reach 15% weight loss, while it takes 12 days for the saturated
salt slurry/solution without additive to reach that approximate
level. This example illustrates that in a low humidity environment,
the saturated salt slurry/solution with additive in example 4 gives
up water more rapidly (approximately 50 to 100% faster) and gives
up more water than the control for a given period of time.
Example 6
[0059] FIG. 9 illustrates water activity (a.sub.w) verses % weight
transfer when the slurries/solutions of Example 4 are placed in a
high humidity environment, i.e. RH of approximately 85%. The days
indicated on the x axis for each set of data represents the same
calendar date. Thus, in FIG. 9, the data point at day 2 shows that
both the formula with the additive (black bar for a.sub.w, and the
light grey line for % weight transfer due to water transfer from
the saturated salt slurry/solution to the surrounding low RH
atmosphere) a.sub.w=0.63, weight transfer=15.9%, while the
saturated salt slurry/solution without additive is shown as a grey
bar for the same day/date with the a.sub.w=0.63, and the % weight
transfer=13.9% as the black line. Alternatively, assessing the
weight transfer from a time perspective, it takes 2 days for the
saturated salt slurry/solution with additive of example 4 to reach
15.9% weight gain, while it takes 2.25 days for the saturated salt
slurry/solution without additive to approximately reach that level.
This example illustrates that in a high humidity environment, the
saturated salt slurry/solution with additive in example 4 gains
water more rapidly (approximately 10 to 15% faster) and gains more
water than the control for a given time frame.
[0060] In addition, the saturated salt slurry/solutions in the
examples above show reduced large crystal formation, improved
viscosity control which may aid in filling during production of
products and no separation or settling after sitting for more than
24 hours which may allow for increased alternatives for storing and
transportation.
[0061] In the examples above, the addition of the additives does
not result in a loss of the "self-indicating" property when a
container (particularly flexible containers) of the saturated salt
slurry/solution has been expended when used in relative humidity
conditions lower than the target relative humidity. Self-indicating
may occur as a hardening or solidification of the slurry/solution
that can be readily felt such as by the fingertips of the user.
Self-indicating may occur when the user feels a flexible container
with the saturated salt slurry/solution therein. If the contents of
the container feel like a hard or stiff gel, for example, the user
may know it is time to replace the saturated salt slurry/solution
to assure continued humidity control protection. The user may then
replace the container with a fresh container of
slurry/solution.
[0062] As used herein, the terms "substantially" or "generally"
refer to the complete or near complete extent or degree of an
action, characteristic, property, state, structure, item, or
result. For example, an object that is "substantially" or
"generally" enclosed would mean that the object is either
completely enclosed or nearly completely enclosed. The exact
allowable degree of deviation from absolute completeness may in
some cases depend on the specific context. However, the nearness of
completion will be so as to have generally the same overall result
as if absolute and total completion were obtained. The use of
"substantially" or "generally" is equally applicable when used in a
negative connotation to refer to the complete or near complete lack
of an action, characteristic, property, state, structure, item, or
result. For example, an element, combination, embodiment, or
composition that is "substantially free of" or "generally free of"
an element may still actually contain such element as long as there
is no significant effect thereof
[0063] In the foregoing description various embodiments of the
present disclosure have been presented for the purpose of
illustration and description. They are not intended to be
exhaustive or to limit the invention to the precise form disclosed.
Obvious modifications or variations are possible in light of the
above teachings. The various embodiments were chosen and described
to provide the best illustration of the principles of the
disclosure and their practical application, and to enable one of
ordinary skill in the art to utilize the various embodiments with
various modifications as suited to the particular use contemplated.
All such modifications and variations are within the scope of the
present disclosure as determined by the appended claims when
interpreted in accordance with the breadth to which they are
fairly, legally, and equitably entitled.
[0064] In the foregoing description various embodiments of the
invention have been presented for the purpose of illustration and
description. They are not intended to be exhaustive or to limit the
invention to the precise form disclosed. Obvious modifications or
variations are possible in light of the above teachings. The
embodiments were chosen and described to provide the best
illustration of the principals of the invention and its practical
application, and to enable one of ordinary skill in the art to
utilize the invention in various embodiments and with various
modifications as are suited to the particular use contemplated. All
such modifications and variations are within the scope of the
invention as determined by the appended claims when interpreted in
accordance with the breadth they are fairly, legally, and equitably
entitled.
* * * * *