Note: Descriptions are shown in the official language in which they were submitted.
CA 02736635 2011-04-01
PROTECTIVE COVER SYSTEM INCLUDING A CORROSION INHIBITOR
FIELD OF THE INVENTION
[0001] The present invention generally relates to the field of covers for
protecting materials
from environmental elements. More particularly, the present invention is
directed to a protective
cover system that includes a corrosion inhibitor.
BACKGROUND OF THE INVENTION
[0002] Attention to corrosion and corrosion mitigation have become
increasingly important for
economic and safety reasons. Based on estimates made in the mid 1990's,
overall costs
attributable to corrosion account for over $100 billion a year in the United
States alone. These
costs typically account for only the direct costs of corrosion and do not
include the associated
indirect costs, such as safety, plant downtime, loss of product, contamination
and over-design.
[0003] Corrosion may be defined as the destructive effect of an environment on
a metal or
metal alloy. Nearly every metallic corrosion process involves the transfer of
electronic charge in
aqueous solution, and most corrosion reactions take place in the presence of
water in either liquid
or condensed vapor phases and also in high humidity. Corrosion is particularly
a problem in
marine environments experienced in places such as shipboard, aboard off-shore
drilling rigs, and
in coastal regions, among others, where seawater enhances corrosion reactions
due to increased
ion transport, pH effects, and elevated dissolved oxygen levels that in turn
enhance levels of
hydrogen ions. Corrosion reactions are further accelerated in marine
environments by
contaminants, such as chloride ions, present in seawater. Corrosion damage to
equipment stored
and used in marine environments is a tremendous problem, impacting maintenance
costs,
availability, repair, and reliability.
[0004] Equipment stored, e.g., onboard a ship or in coastal regions, is often
stored in protective
storage systems that have proved to be less than optimally effective. At best,
such equipment is
covered with waterproof tarpaulins, although often, especially for shipboard
equipment, it is not
covered properly and is directly exposed to a marine environment, which leads
to rapid
corrosion. Even when equipment is covered by waterproof tarpaulins, seawater
still penetrates
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CA 02736635 2011-04-01
through and/or around the tarpaulins into the protected spaces where it
collects and corrodes the
underlying equipment. Also, conventional storage systems can be cumbersome to
use and
maintain, and are therefore often avoided. As a result, corrosion continues to
be a significant and
costly problem, requiring many hours of rust removal, painting, and repair
that often lead to
premature equipment replacement.
[0005] FIG. 1 shows a conventional waterproof cover 20 used to protect an
object, such as
metallic object 22 resting on a surface 24, from moisture, such as rain, sea
spray, dew and the
like. Cover 20 has an outer surface 26, an inner surface 28, and an area 30
defined by a
peripheral edge 32. Cover 20 is shown covering object 22 in a typical manner,
wherein a
microenvironment is generally defined by the space enclosed by the cover. The
microenvironment comprises a number of interior regions, such as regions 34,
located between
cover 20 and object 22.
[0006] Generally, conventional covers, such as cover 20, comprise at least one
liquid-
impermeable layer made of, e.g., a tightly-woven polymer fabric or a non-woven
structure, such
as a continuous film or other membrane. More complex conventional covers may
include one or
more additional layers that provide them with additional features, such as
highly durable outer
surfaces to withstand harsh environments and non-abrasive inner-surfaces to
minimize
mechanical damage to the object covered. Other conventional covers are made of
vapor-
permeable, porous materials, such as expanded polytetrafluoroethylene or the
like.
[0007] The air in interior regions 34 generally never has a moisture content
less than the
moisture content of the ambient environment. If the moisture content of the
ambient
environment rises, the moisture content of regions 34 also rises due to the
inflow of moisture
(illustrated by arrow 36) through gaps between cover 20 and surface 24 at
peripheral edges 32 of
the cover. Eventually, the moisture content of the ambient environment 38 and
regions 34
equalize. Once the additional moisture is in the microenvironment, it can
become trapped, as
illustrated by arrows 40. Moisture levels can quickly become elevated, and the
air saturated. In
such a case, condensation could occur on the object 22. Because the moisture
content of interior
regions 34 never falls below that of ambient environment 38, conventional
covers are not very
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effective in high moisture environments, such as marine and high-humidity
environments.
Moreover, once moisture enters the microenvironment, it can take a long time
to dissipate, if at
all.
SUMMARY OF THE INVENTION
[0008] In one aspect, the present invention is directed to a protective cover
system for
protecting an object by defining a microenvironment adjacent the object when
the protective
cover system is applied to the object. The protective cover system comprises a
cover for being
applied to the object and defining a microenvironment when the cover is
applied to the object.
The cover includes a first layer that comprises a non-porous water-vapor-
permeable layer. A
corrosion inhibitor source provides at least one corrosion inhibitor to the
microenvironment
when the cover is applied to the object. The corrosion inhibitor source is in
communication with
the microenvironment when the cover is applied to the object so that at least
some of the
corrosion inhibitor may enter the microenvironment.
[0009] In another aspect, the present invention is directed to a protective
cover system for
inhibiting corrosion of an object by forming a microenvironment adjacent the
object when the
protective cover system is applied to the object. The protective cover system
comprises a cover
that includes a first layer having a first face and a second face. The first
layer comprises an
absorbent material adapted to absorb and store moisture. A second layer is
located adjacent the
first face of the first layer and is liquid-impermeable. A corrosion inhibitor
source that
comprises at least one corrosion inhibitor fluidly communicates with the
microenvironment
when the cover is applied to the object.
[0010] In a further aspect, the present invention is directed to a panelized
cover system for
protecting an object from moisture. The panelized cover system comprises a
plurality of panels
each comprising a first layer having a first face and a second face. The first
layer comprises an
absorbent material adapted to absorb and store the moisture. A second layer is
located adjacent
the first face of the first layer. The second layer is liquid-impermeable.
Each of the plurality of
panels is fastened to at least one adjacent one of the plurality of panels.
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BRIEF DESCRIPTION OF THE DRAWINGS
[00111 For the purpose of illustrating the invention, the drawings show a form
of the invention
that is presently preferred. However, it should be understood that the present
invention is not
limited to the precise arrangements and instrumentalities shown in the
drawings, wherein:
FIG. 1 is a cross-sectional view of a prior art cover shown covering an
object;
FIG. 2 is a cross-sectional view of a protective cover system of the present
invention showing the
cover thereof covering an object;
FIG. 3 is a cross-sectional view of a portion of one embodiment of the
protective cover system of
the present invention;
FIG. 4 is a cross-sectional view of a portion of an alternative embodiment of
the protective cover
system of the present invention;
FIG. 5 is an enlarged view of one edge of the cover shown in FIG. 2, for a
particular embodiment
of the cover of the present invention;
FIG. 6 is a perspective view showing an embodiment of the protective cover of
the present
invention comprising a plurality of panels removably secured to one another;
FIG. 7 is an enlarged cross-sectional view of one of the peripheral edges of
one of the panels
taken along line 7-7 of FIG. 6; and
FIGS. 8A-C are each an enlarged cross-sectional view of a portion of other
alternative
embodiments of the protective cover system of the present invention; and
FIG. 9 is an enlarged cross-sectional view of a portion of another alternative
embodiment of the
protective cover system of the present invention having a corrosion inhibitor
contained in a
container separate from the cover.
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DETAILED DESCRIPTION OF THE DRAWINGS
[0012] Referring now to the drawings, wherein like numerals indicate like
elements, FIG. 2
illustrates a protective, corrosion-inhibiting cover system, which is
generally denoted by the
numeral 100. Cover system 100 may include a cover 101 that may be made of
flexible materials
and includes an outer surface 102, an inner surface 104, and a peripheral edge
106 that defines an
area 108, which may be shaped as desired to suit a particular application.
Alternatively,
cover 101 may include rigid materials that may be formed into a shape
conforming to the shape
of the object to be covered or to another shape suitable for that object. When
covering an object,
such as a metallic object 110 resting on a surface 112, outer surface 102 is
exposed to an ambient
environment 114 and inner surface 104 defines a microenvironment comprising
one or more
interior regions, such as the interior regions 116, located between inner
surface 104 and
object 110 and/or surface 112.
[0013] Although object 110 is generally protected from elements present in
ambient
environment 114 by cover 101, often moisture from the ambient environment
tends to infiltrate
(as illustrated by arrow 118) interior regions 116 through gaps between
peripheral edge 106 of
the cover and surface 112. A feature of the present invention allows cover 101
to absorb and
store such infiltrating moisture (as illustrated by arrows 120), and other
moisture trapped within
interior regions 116, so as to maintain the moisture content of the
microenvironment at a low
level, often below the moisture content of ambient environment 114. Another
feature of the
present invention allows cover 101 to absorb and store by wicking action any
water present on
the surface of object 110 that comes into contact with inner surface 104 of
the cover. The result
is a low-moisture microenvironment that inhibits metallic object 110 from
corroding.
[0014] Yet another feature of the present invention permits cover 101 to
regenerate its
moisture-absorbing and storing features by diffusing stored moisture to outer
surface 102 of the
cover, where it can evaporate (as illustrated by arrows 122) into ambient
environment 114 when
conditions there are suitable for evaporation. A further feature of the
present invention is the
ability to disperse one or more corrosions inhibitors into regions 116 of the
microenvironment
CA 02736635 2012-05-28
formed beneath cover 101 so that the corrosion inhibitors are deposited on the
surface of metallic
object 110, e.g., as a film.
[0015] As discussed in more detail below, each of these and other features may
be incorporated
into protective cover system 100 of the present invention either singly or in
various combinations
with one another. For example, one embodiment of cover 101 may be provided
with the
moisture absorbing feature, but not the corrosion inhibitor feature. Likewise,
another
embodiment may be provided with the corrosion inhibitor feature, but not the
moisture-
absorbing feature. Of course, another embodiment may include both the moisture
absorbing and
corrosion inhibitor feature. Each of these embodiments may optionally be
augmented or
supplemented as desired and/or appropriate with various other features, such
as the surface
wicking, edge wicking, radar influencing, evaporation augmenting, and
panelization features,
among others, described herein.
[0016] A beneficial attribute of protective cover system 100 of the present
invention is that it
can be made to any size and shape necessary to protect an object having
virtually any size and
surface profile. Some diverse examples of such objects are containers for
container ships, deck-
mounted guns on naval ships, construction equipment, stored construction
materials, air
conditioning units and barbeque grills, to name just a few. Pouches made from
cover 101 could
be fashioned to store munitions, tools, handguns and telephones and other
electronic devices to
name just a few. One skilled in the art will recognize that there is a vast
range of applications for
protective cover system 100 of the present invention.
[0017] FIG. 3 shows one embodiment of protective cover system 100 of the
present invention,
which may include a cover identified by the numeral 200. Cover 200 may
comprise a liquid-
permeable layer 202, a liquid-impermeable layer 204, and a moisture-absorbing
layer 206
sandwiched between the liquid-permeable and liquid-impermeable layers. With
reference to
FIGS. 2 and 3, liquid-permeable layer 202 generally defines inner surface 104
of cover 200 and
may, among other things, retain the constituent material(s) (described below)
of moisture-
absorbing layer 206 within the cover. Liquid-permeable layer 202 may be vapor
permeable to
allow moisture vapor within interior regions 116 to reach moisture-absorbing
layer 206 and
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CA 02736635 2011-04-01
liquid-permeable to allow any liquid water contacting inner surface 204 of
cover 200 to be
wicked into the moisture-absorbing layer. In a typical embodiment, liquid-
permeable layer 202
has a water transmission rate that is greater than 10 g/m2-hr, although the
present invention
encompasses the use of liquid-permeable layers having somewhat lower water
transmission
rates. Liquid-permeable layer 202 may be made of any suitable material, such
as wovens, knits,
perforated films, open-cell foams, melt-blowns, or spunbonds, among others, or
combination of
materials, e.g., a woven material coated with a porous open-cell foam, that is
liquid and vapor
permeable. Those skilled in the art will appreciate the breadth and variety of
materials that may
be used for liquid-permeable layer 202 such that an exhaustive recitation of
such materials is
unnecessary for those skilled in the art to understand the broad scope of the
present invention.
[0018] For some applications, it is generally preferable, but not necessary,
that liquid-
permeable layer 202 be made of a material that can withstand repeated use and
continual contact
with a wide variety of surfaces. It may also be preferable for some
applications that liquid-
permeable layer 202 be relatively smooth and/or soft so that damage to an
object contacted by
liquid-permeable layer 202 may be avoided. An example of a material suitable
for liquid-
permeable layer 202 is the K-TooTM un-backed knitted nylon available from HUB
Fabric Leather
Company, Inc., Everett, MA. Other suitable materials include polyester mesh
Style No. 9864,
available from Fablock Mills, Murry Hill, NJ, and nylon, polypropylene, and
other knits that are
available from Fablock Mills Inc., Murry Hill, NJ, Jason Mills Inc., Westwood,
NJ, and Apex
Mills, Inwood, NY, among others. These few examples of knits are merely
several particular
materials the inventors have found suitable. Those skilled in the art will
readily appreciate that
suitable non-knit materials are widely available and readily substitutable for
the knit materials
mentioned above. Accordingly, those skilled in the art will also readily
appreciate that an
exhaustive presentation of exemplary materials is not necessary to understand
the broad scope of
the present invention.
[0019] Moisture-absorbing layer 206 may include any suitable absorbent
material or
combination of materials. For example, moisture-absorbing layer may contain a
matrix 210 and
a superabsorbent material 208, e.g., hydrogel, among others, dispersed within
the matrix. Those
skilled in the art will understand that many superabsorbent and matrix
materials are known and
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CA 02736635 2011-04-01
may be used in conjunction with the present invention. For example, U.S.
Patent No. 6,051,317
to Brueggemann et al. describes a number of superabsorbent and matrix
materials that may be
used within moisture-absorbing layer 206. Superabsorbent material 208 may be
provided as
particulate, fiber, or other form, which allows it to be dispersed throughout
matrix 210.
Alternatively, superabsorbent material 208 may be located in a generally
discrete layer within
matrix 210.
[00201 Examples of acceptable materials for matrix 210 include wool,
fiberglass, polymer
fleece, fluff wood pulp, and the like. It is desirable that fiber matrix 210
be hydrophilic and have
a high capillarity, e.g., greater than 10 g/m2-hr (although lower capillarity
rates are encompassed
in the present invention), so that moisture coming into contact with moisture-
absorbing layer 206
through liquid-permeable layer 202 may be wicked deep into moisture-absorbing
layer 206 to
take advantage of the superabsorbent material located there, if any. Although
matrix 210 is
shown, it may be eliminated in an alternative embodiment having superabsorbent
material 208 in
a form that need not be supported by, and/or located within, a matrix.
[00211 As mentioned, hydrogel is one example of a class of superabsorbent
materials suitable
for superabsorbent material 208. Some forms of hydrogel are capable of
absorbing up to
400 times their weight in water. With such a large absorption capability,
particles of hydrogel
can swell to many times their original size. If the hydrogel particles are not
distributed properly
throughout fiber matrix 210, moisture-absorbing layer 206 may experience
"hydroblocking,"
wherein the hydrogel particles closest to the moisture source swell so much
that they block
moisture from being wicked farther into the fiber matrix. Although some of the
absorbed
moisture eventually reaches the hydrogel located deep within matrix 210 by
diffusion, diffusion
is a relatively slow process that may degrade the usefulness of a cover
experiencing
hydroblocking, particularly in high-moisture conditions. Therefore, it is
recommended care be
taken to distribute a hydrogel-type superabsorbent material 208 within matrix
210 in a manner
that minimizes, or eliminates, hydroblocking so that when the superabsorbent
material and
matrix adjacent liquid-permeable layer 202 is saturated, the matrix is still
able to wick water
deeper into moisture-absorbing layer 206.
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[0022] Liquid-impermeable layer 204 may define outer surface 102 of cover 200
and may be
selected to generally prevent liquid in ambient environment 114, such as rain,
sea spray, dew,
and the like, from reaching interior regions 116 beneath the cover. It is
preferable, but not
necessary, that liquid-impermeable layer 204 be made of one or more vapor-
permeable materials
to allow moisture stored in moisture-absorbing layer 206 and/or present in
interior regions 116 of
the microenvironment to escape into ambient environment 114 by diffusion and
evaporation as
described above. In a typical embodiment, liquid-impermeable layer 204 has a
vapor
transmission rate of greater than 1 g/m2-hr, although liquid-impermeable
layers with lower vapor
transmission rates may also be employed in certain circumstances.
[0023] The liquid transmission rate through the liquid-impermeable layer 204
should be less
than the employed vapor transmission rate for this layer. For the typical
lower bound of 1 g/m2-
hr. of vapor transmission through liquid-impermeable layer 204, a liquid
transmission rate
through this layer could be any value less than 1 g/m2-hr. If the vapor
transmission rate were
greater, the corresponding acceptable level of liquid transmission would be
greater, as long as it
remained less than the vapor transmission rate. By allowing stored moisture to
escape,
cover 200 is capable of regenerating itself, i.e., losing previously absorbed
and stored moisture to
ambient environment 114, e.g., by evaporation, during periods of low moisture
in the ambient
environment so that it may absorb and store more moisture during a subsequent
period when
interior regions 116 again become moisture laden. Beneficially, liquid-
impermeable layer 204
may also be designed to absorb solar energy to provide heat to cover 200 that
accelerates
regeneration of moisture-absorbing layer 206.
[0024] Liquid-impermeable layer 204 may comprise any suitable woven or non-
woven
material or a combination of the two. As used herein and the claims appended
hereto, the term
non-woven shall include any material that is not woven, e.g., a film, knit,
foam, felt, melt-blown,
spunbond, air-laid, cast material, extruded material, and molded material,
among others. For
example, in one embodiment of cover 200 wherein liquid-impermeable layer 204
is vapor
permeable, the liquid-impermeable layer may include one or more layers of
various porous,
vapor-permeable materials, such as a laminate of a 200 denier nylon inner
layer and a breathable
urethane outer layer. Such a nylon/urethane laminate is available from
LAMCOTEC
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CA 02736635 2011-04-01
Incorporated, Monson, MA. Other suitable porous vapor-permeable materials
include expanded
polytetrafluroethylene, GORE-TEX fabric (W. L. Gore & Associates, Inc.,
Newark, DE),
SUNBRELLA fabric (Glen Raven Mills Inc., Glen Raven, NC), Hub Semi-Permeable
fabric
(Hub Fabric Leather Company, Everett, MA) or the like, may alternatively be
used. Like liquid-
permeable layer 202, those skilled in the art will appreciate that the
foregoing examples of
suitable porous, vapor-permeable materials for liquid impermeable layer 204
are merely
representative of the many materials that may be used for this layer.
Accordingly, an exhaustive
list of such suitable materials herein is not necessary for those skilled in
the art to understand the
broad scope of the present invention.
[00251 In another embodiment of cover 200, liquid-impermeable layer 204 may
include a non-
porous, water-vapor-permeable film that allows moisture contained within
moisture-absorbing
layer 206 to be transported into ambient environment 114 when conditions are
suitable for such
transport to occur. Examples of such non-porous, water vapor permeable films
include the
copolyether ester films described in U.S. Patent No. 4,493,870 to Vrouenraets
et al., e.g.,
SYMPATEX film available from SympaTex Technologies GmbH, Wuppertal, Germany,
the
copolyether amide films described in U.S. Patents Nos. 5,989,697 and
5,744,570, both to
Gebben, and films comprising a tetrafluoroethylene matrix interspersed with
sulfonic acid
groups, e.g., NAFION film available from E.I. DuPont de Nemours Company,
Wilmington,
Delaware, among others.
[00261 Generally, these films are non-porous so that liquid water and other
substances cannot
pass through them. It is believed that each of these films works on a
molecular level to transport
water molecules from a region on one side of the film having a relatively
higher moisture content
to a region on the other side of the film having a relatively lower moisture
content by an
adsorption/desorption process within special hydrophilic polymer regions of
the film. Typically,
but not necessarily, each of these non-porous, water vapor permeable films
would be
continuously bonded, or otherwise attached, to a backing layer that provides
support for the film.
This is so because these films are generally very thin, e.g., on the order of
tens of microns thick
and, standing alone, would typically not be robust enough for some of the
contemplated
applications of cover 200 of the present invention. An example of such a
laminated composite is
CA 02736635 2011-04-01
a 500 denier woven CORDURA nylon fabric, which has been acid dyed and treated
with a
durable water repellent, laminated to a 15 micron thick SYMPATEX film
(CORDURA is a
registered trademark of E.I. DuPont de Nemours and Company, Wilmington, DE).
This laminate
is available from Brookwood Companies, Inc., New York, NY.
[00271 In an alternative embodiment, cover 200 may further include a heating
element 212 (FIG. 3) that would allow moisture-absorbing layer 206 to
regenerate more quickly
or regenerate when the conditions in ambient environment 114 would otherwise
not permit
evaporation of the stored moisture. Such a heating element may comprise an
electrical resistance
wire grid located within one of the layers or between adjacent layers.
Alternatively, the heating
element may comprise arrays of thin, flexible heating elements consisting of
etched-foil resistive
elements laminated between layers of flexible insulation like KAPTON , NOMEX ,
silicone
rubber, or mica, or arrays of thin film ceramic elements available from Minco
Products
Incorporation, Minneapolis, MN and Watlow Gordon, Richmond, IL among others
(KAPTON
and NOMEX(K are registered trademarks of E.I. DuPont de Nemours and Company,
Wilmington, DE). Those skilled in the art will appreciate the variety of
heating elements 212
that may be incorporated into cover 200 if this feature is desired.
[00281 In another alternative embodiment, cover 200 may further include a
corrosion
inhibitor 214 (FIG. 3) incorporated into one or more of layers of the cover
discussed above, into
an additional layer, and/or into one of more corrosion inhibitor sources
generally separate from
the cover. If one or more separate corrosion inhibitor sources are provided,
each may be located
within the microenvironment defined by the cover, e.g., in an interior region
116, or otherwise
placed into communication with the microenvironment so that corrosion
inhibitor (214) may
enter the microenvironment and provide protection to metallic object 110 (FIG.
2). Examples of
suitable materials for use as corrosion inhibitor 214 include vapor, or vapor-
phase, corrosion
inhibitors (VCIs) (also known as "volatile corrosion inhibitors"), contact
corrosion inhibitors,
and migrating corrosion inhibitors, among others. Generally, VCIs are volatile
compounds that
emit ions that condense on metallic surfaces to form a mono-molecular layer
that interacts with
corrosion agents to protect the surface. Contact corrosion inhibitors
generally require surface-to-
surface contact with the object to be protected in order to provide protection
(although they may
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CA 02736635 2011-04-01
also migrate from one region to another to some extent). Migrating corrosion
inhibitors migrate
through a solid diffusion process. Each of these types of corrosion inhibiting
materials is
generally continuously self-replenishing and environmentally benign. These
corrosion inhibiting
materials may be used alone or in combination with one another as desired to
suit a particular
application.
[0029] Examples of corrosion inhibiting materials include, among others,
cyclohexylammonium benzoate, ethylamino benzoate, calcium sulfonate, calcium
carbonate,
sodium benzoate, amine salts, ammonium benzoate, silica, sodium sulfonate,
triazole derivatives,
such as toltriazol and benzotriazol, alkali dibasic acid salts, alkali
nitrites, such as sodium nitrite,
tall oil imidazolines, alkali metal molybdates, dyclohexylammonium nitrate,
cyclohexylamine
carbonate, and hexmethyleneimine nitrobenzoate. These VCIs materials may be
obtained from a
number of sources, including Cortec Corporation, St. Paul, Minnesota, Daubert
Coated Products
Incorporated, Westchester, Illinois, Poly Lam Products, Buffalo, New York, Mil-
Spec Packaging
of Georgia Incorporated, Macon, Georgia, and James Dawson Enterprises Limited,
Grand
Rapids, Michigan, among others. U.S. Patent No. 6,028,160 to Chandler et al.
lists the foregoing
and other compounds that may be suitable for use as corrosion inhibitor 214.
[0030] As mentioned, corrosion inhibitor 214 may be incorporated into one or
more of the
above-described layers of cover, provided in one or more layers separate from
the layers of the
cover, or may be provided in a separate corrosion inhibitor source, among
other alternative.
When provide as a separate layer, corrosion inhibitor 214 may be incorporated
into a coating
applied to one or more of the layers, e.g., one or more of layers 202, 204,
206, or incorporated
into a separate layer (not shown), e.g., a separate film, woven, knit, melt-
blown, spunbond, foam,
or other layer, comprising a suitable vehicle material, such as polyethylene,
polypropylene, or
nylon, among others. Those skilled in the art will understand how the various
corrosion
inhibiting materials may be combined with various resins and other bases for
providing a vehicle
for the corrosion inhibiting materials. For example, U.S. Patent No. 6,028,160
to Chandler et al.,
mentioned above, discusses vehicle resin/VCI blends in the context of
biodegradable polymeric
films. Similar formulations may be used for non-biodegradable films. In
addition, a vehicle
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resinNCl blend may be used form a structure other than film, such as the
woven, knit, melt-
blown, spunbond, and foam structures noted above.
[0031] The addition of a corrosion inhibitor 214 to cover 200 can enhance the
corrosion
inhibiting ability of the cover by allowing the cover to continue to provide
protection when the
moisture-absorbing layer is overwhelmed. When moisture-absorbing layer 206 is
present, which
it need not be (see FIGS. 8A-C and accompanying discussion), corrosion
inhibitor 214 may
benefit from the presence of the moisture-absorbing layer because this layer
removes the burden
from the corrosion inhibitor by not requiring it to offer protection at all
times. It is noted that
corrosion inhibitor 214 may be provided to any embodiment of the cover of the
present
invention, such as those shown in FIGS. 4-8, and in any form, such as a
coating, a separate layer,
incorporation into one or more of the liquid-permeable, moisture-absorbing,
and liquid-
impermeable layers, and a separate source, each of which is described herein.
[0032] Layers 202, 204, 206 may be secured to one another in any suitable
manner. For
example, these layers may be bonded to one another throughout area 108 of
cover 200 in a
manner that does not interfere with its liquid and vapor transport features,
yet retains the layers
in physical proximity to one another. Bonding processes known in the art may
be used to bond
or join the layers of cover 200. For example, bonding processes such as
thermal bonding or
multi-component adhesive bonding may be used. Alternatively, the various
layers of cover 200
may be secured to one another by other means, such as stitching, or other
mechanical fasteners,
e.g., rivets, among others.
[0033] Depending on the size and materials of the cover, it may only be
necessary to provide
stitching adjacent peripheral edge 106. In other uses, it may be desirable to
provide quilt-
stitching throughout the area. Similarly, bonding may be continuous, only at
peripheral edges, or
in a quilted fashion, among others. Of course, various combinations of
fastening means may be
used for securing different layers to one another and/or to secure the layers
in different regions of
cover 200. For example, liquid-impermeable layer 206 may be secured to
moisture-absorbing
layer 206, e.g., by continuous bonding, whereas liquid-permeable layer 202 may
be secured to
the bonded combination of the liquid-impermeable and moisture-absorbing
layers, e.g., by quilt
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stitching in area 108 and by continuous stitching adjacent peripheral edge
106. Those skilled in
the art will appreciate the many variations of securing the various layers of
cover 200 to one
another such that an exhaustive recitation of all possible securing means need
not be described in
detail herein.
[0034] In a further alternative embodiment, liquid-impermeable layer 204 may
be removably
secured to the other two layers 202 and 206 to allow it to be removed to speed
regeneration of
the moisture-absorbing layer in times of favorable conditions in ambient
environment. Re-
fastenable fasteners, such as hook-and-loop fasteners, snaps, zippers and the
like, may be
provided to facilitate this feature. Additionally, moisture-absorbing layer
206 may be bonded or
formed via an airlaid process known in the art as a process of producing a
nonwoven web of
fibers in sheet form where the fibers are transported and distributed via air
flows where the entire
sheet is then set with a mixture of binders and resins.
[0035] FIG. 4 shows another specific embodiment of cover 101 of the present
invention, which
is identified by the numeral 300. Cover 300 may comprise the three layers of
cover 200 shown
in FIG. 3, i.e., a liquid-permeable layer 302, a liquid-impermeable layer 304
and a moisture-
absorbing layer 306 (these layers being identical, respectively, to layers
202, 204 and 206). In
addition to these layers, cover 300 may further includes a radar-influencing
layer 308. Radar-
influencing layer 308 may comprise a radar-absorbing material 310, a radar-
reflecting
material 312 or a combination of both, depending upon the desired radar
profile of cover 300.
With reference to FIG. 2, it may be preferable to have entire area 108 of
cover 300 be radar-
attenuating. For example, in a military application it may be necessary to
reduce the radar
profile of a large object to conceal its identity. On the other hand, it may
be preferable to have
entire area 108 be radar-enhancing. For example, in a civilian application it
may be
advantageous to increase the radar profile of a small water craft to
accentuate its presence. In
another instance, it may be desirable to provide area 108 with alternating
discrete radar-
attenuating, radar-enhancing, and/or radar neutral regions to give cover 300 a
custom radar
profile.
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[0036] Although radar-influencing layer 308 is shown located between liquid-
impermeable
layer 304 and moisture-absorbing layer 306, it may be located elsewhere. For
example, the
radar-influencing layer may be located between moisture-absorbing layer 306
and liquid-
permeable layer 304, adjacent outer surface 102 of cover 200, or the like. In
addition, radar-
absorbing material 310 and radar-reflecting material 312 may be incorporated
into one or more
of liquid- permeable layer 304, moisture-absorbing layer 306, and liquid-
permeable layer 302.
Generally, care should be taken, however, to select radar-absorbing and
reflecting materials 310,
312 that do not interfere with the vapor and liquid transport features of
cover 300.
[0037] Radar-absorbing material 310, may comprise polypyrrole-coated polyester
fibers, or the
like, that may be made into a thread that is then woven into a discrete fabric
layer or one or more
of layers 302, 304, 306 of cover 300. Such textiles are available from
Milliken & Co.,
Spartanburg, South Carolina under the trademark CONTEX . Alternatively, radar-
absorbing
material 310 may comprise discrete particles and/or fibers of carbon,
graphite, or the like
dispersed within a fiber matrix or a coating that is applied to one of layers
302, 304, 306, or is
applied to a separate layer that is then incorporated into cover 300. Other
examples of radar-
absorbing materials are REX radar-absorbing mats (Milliken & Co., Spartanburg,
South
Carolina) and RFWP Weatherproof Foam (R&F Products, Inc., San Marcos,
California). Similar
techniques may be used for radar-reflecting material 312, except that a metal,
such as silver,
copper, or compounds of such metals, or the like, which may be provided as a
thread, discrete
particles, or other form incorporated into cover 300 in any suitable manner.
[0038] Referring now to FIGS. 2 and 5, there is shown yet another embodiment
of cover 101 of
the present invention, which is identified by the numeral 400. In FIG. 5,
cover 400, which may
have the five-layer construction shown, is illustrated with its peripheral
edge 106 contacting
surface 112, which may be, e.g., a ship's deck, tarmac, or other similar
surface. In such
applications, it can be common for a large amount of liquid water to be
absorbed by cover 400 at
regions adjacent peripheral edge 106. This is so because much of the water
from ambient
environment 114, such as rain, sea spray, dew and the like, repelled by cover
400 from area 108
travels down the sloping portions of the cover, ending up adjacent peripheral
edge 106. To
prevent saturation of cover 400 in regions adjacent peripheral edge 106,
additional layers may be
CA 02736635 2011-04-01
added to the three layer structure of FIG. 3 to provide a separate zone for
absorbing and storing
moisture that may accumulate on surface 112.
[0039] Accordingly, cover 400 may include an outer liquid-impermeable layer
402, a first
moisture-absorbing layer 404, an intermediate liquid-impermeable layer 406, a
second moisture
absorbing layer 408, and a liquid-permeable layer 410, which may confront one
another in the
recited order as shown. The primary purpose of outer liquid-impermeable layer
402 is to prevent
liquid water, such as rain, sea spray, dew and the like, from penetrating into
the
microenvironment, e.g., interior regions 116, beneath cover 400. Outer liquid-
impermeable
layer 402 may include a return 412 to provide a seamless, robust structure at
peripheral edge 106.
The primary function of first moisture absorbing layer 404 is to absorb and
store moisture that
collects on surface 112, whereas the primary function of second moisture
absorbing layer 408 is
to absorb and store moisture trapped in the microenvironment beneath cover
400.
[0040] Intermediate liquid-impermeable layer 406 prevents liquid moisture
stored in each of
the moisture-absorbing layers from migrating to the other of such layers. At
regions adjacent
peripheral edge 106, this separation prevents second moisture-absorbing layer
408 from
becoming overburdened by moisture from surface 112. Preferably, both liquid-
impermeable
layers are vapor permeable to allow cover 400 to regenerate passively by
losing stored moisture
to ambient environment 114 when conditions there permit.
[0041] The peripheral edge of the intermediate liquid-impermeable layer 406 is
laterally spaced
from peripheral edge 106 of cover 400 around the entire periphery of the cover
to define an
opening 414. When cover 400 is draped over an object, such as metallic block
110, opening 414
may contact, or be slightly spaced from, surface 112, allowing any moisture
present on that
surface to be wicked into first moisture-absorbing layer 404. Depending on
design parameters,
such as materials selected, volume of moisture to be absorbed, and the like,
the width 416 of
opening 414 may be varied accordingly.
[0042] FIGS. 6 and 7 show a cover 500 according to the present invention,
wherein the cover is
panelized into a number of discrete panels, each denoted 502 and having an
outer surface 504, an
16
CA 02736635 2011-04-01
inner surface 506, and a peripheral edge 508. Panels 502 may be removably
secured to one
another, and to other panels (not shown) of similar construction, with
fasteners 510 located
adjacent peripheral edge 508 of cover 500. Panelization allows cover 500 of
the present
invention to be assembled to fit the size and shape necessary for a particular
application. To
further enhance customization, one or more of the panels may be formed into a
shape other than
the rectangular shapes shown in FIG. 6. Panels 502 may be any size desired to
suit a particular
application, with smaller size panels typically, but not necessarily, being
used to conform
cover 500 to highly contoured surfaces. For example, for relatively large
objects having regions
of high contour, panels 502 may be on the order of 1 ft2 (0.093 m2). Of
course, panels 502 may
be larger or smaller depending upon the application, and different panels
within cover 500 may
differ in size from one another. Larger panels 502 may be on the order of 100
ft2 (9.290 m2),
1,000 ft2 (92.903 m2), or more.
[00431 Fasteners 510 may be of the hook-and-loop type, which typically
includes a flexible
hook strip 512 and a flexible loop strip 514. Hook strip 512 and loop strip
514 may alternately
be secured to outer and inner surfaces 504, 506 adjacent peripheral edge 508
so that when the
peripheral edge of one panel is overlaid the peripheral edge of another panel
the hook and loop
strips engage one another to secure the panels to one another. Loop strip 508
may be liquid-
permeable so that its presence does not interfere with the moisture absorbing
properties of
cover 500 at its peripheral edge 508. Such hook-and-loop fasteners may be
VELCRO brand
hook-and-loop fasteners (Velcro Industries B.V., Curacao, Netherlands) or the
like.
Alternatively, other types of fasteners such as buttons, zippers, snaps, hook
and eyelet, eyelet and
lacing, among others, may be used for fasteners 504 or the panels may be sewn
together.
[0044] In the embodiment shown, each panel 502 comprises a three-layer
structure of a liquid-
impermeable outer layer 516, a moisture-absorbing intermediate layer 518 and,
a liquid-
permeable inner layer 520, which are identical, respectively, to layers 204,
206, 202 of cover 200
of FIG. 3. However, those skilled in the art will readily appreciate that each
panel 502 may have
any other construction, such as the construction of covers 300, 400, and 600,
described above
and below. In this connection, each panel 502 may include any combination of
layers and/or
features described herein desired to suit a particular application.
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CA 02736635 2011-04-01
[0045] FIG. 8A shows another cover 600 of protective cover system 100 of the
present
invention. Cover 600 may include a water-vapor-permeable layer 602 and at
least one corrosion
inhibitor 604. Water-vapor-permeable layer 602 may be made of any suitable
porous or non-
porous water-vapor-permeable material, which includes the expanded
polytetrafluoroethylene,
copolyether ester, copolyether amide, and tetrafluoroethylene/sulfonic acid
materials described
above in connection with liquid-impermeable layer 204 of cover 200 (FIG. 3),
among others. A
non-porous water-vapor-permeable layer 602 may have a functional advantage
over conventional
porous liquid-impermeable materials in that not only do these non-porous
materials prevent the
passage of liquid water through the layer, but they typically also prevent
molecules of corrosion
inhibitor 604 from passing therethrough. Most conventional porous water-vapor-
permeable
layers allow at least the smallest molecules of corrosion inhibiting materials
to pass through
them.
[0046] Typically, but not necessarily, water-vapor-permeable layer 602 is a
relatively thin
layer, often on the order of about 5 microns to about 100 microns, or greater,
thick. Such a thin
layer is generally not practicable for use as a stand-alone protective layer,
particularly for large
protective covers subject to harsh weather elements. Therefore, cover 600 may
also include a
support layer 606, which may be made of a relatively durable and water-vapor-
permeable
material to provide a generally robust, but breathable, outer shell. Support
layer 606 may be
continuously bonded to liquid-impermeable layer and may be made of any
suitable porous
material, such as the woven, film, knit, foam, felt, melt-blown, spunbond,
cast, extruded, molded,
and expanded materials described above in connection with liquid-permeable
layer 202 and
liquid impermeable 204 layer of cover 200 (FIG. 3), among others.
[0047] Corrosion inhibitor 604 may be any one or more corrosion inhibiting
materials,
including the corrosion inhibiting materials noted above with respect to
corrosion inhibitor 214
of cover 200. Like corrosion inhibitor 214, corrosion inhibitor 604 may be
provided to
cover 600 in any one of a number of ways. For example, FIG. 8A shows corrosion
inhibitor 604
as being incorporated into water-vapor-permeable layer 604. This may be
accomplished, e.g., by
adding one or more corrosion inhibiting materials to the resin of water-vapor-
permeable layer
18
CA 02736635 2011-04-01
604. Resin/corrosion inhibitor blending is discussed above in the context of
VCIs in connection
with cover 200. Similarly, FIG. 8B shows corrosion inhibitor 604 as being
incorporated into an
optional liquid- and/or vapor-permeable layer 608 located adjacent the
interior face of water-
vapor-permeable layer 602, e.g., by blending one or more corrosion inhibiting
materials with the
resin of layer 608. Layer 608 may be attached to layer 602 either continuously
or intermittently,
or may not be attached to layer 602 at all, except perhaps at the outer
periphery (not shown) of
cover 600.
[00481 FIG. 8C shows corrosion inhibitor 604 as being incorporated into a
coating 610 applied
to cover 600, e.g., to water-vapor-permeable layer 602. Depending upon the
permeability of
coating 610, the coating may be applied either continuously or intermittently
such that water-
vapor-permeable layer 602 can provide its vapor-transport function. Coating
610 may comprise
any one or more of the corrosion inhibiting materials identified above, or
other corrosion
inhibiting material(s), in a binder suitable for being applied to cover 600 as
a coating.
[00491 FIG. 9 shows corrosion inhibitor 604 contained in separate corrosion
inhibitor
source 612. Corrosion inhibitor source 612 may be any suitable source, other
than
layers 602, 606, 608 and coating 610 described above, for holding and
releasing one or more
corrosion inhibiting materials into the microenvironment defined by cover,
e.g., regions 116 of
FIG. 2. For example, corrosion inhibitor source 612 may comprise a container
614 and a
closure 616 suitably secured to the container. Closure 616 and/or container
614 may include one
or more apertures 618 for allowing corrosion inhibitor 604 to escape therefrom
and into the
microenvironment beneath cover 600. Corrosion inhibitor source 612 may be
placed anywhere it
may be in communication with the microenvironment, e.g., by placing it in one
of interior
regions 116, so that corrosion inhibitor 604 may enter the microenvironment
and provide
protection to metallic object 110 (FIG. 2). If desired, corrosion inhibitor
source 612 may be
located outside the microenvironment and placed into communication with the
microenvironment using one or more ducts or other conduits (not shown) that
communicate with
the microenvironment.
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CA 02736635 2011-04-01
[00501 Depending upon the size of the object to be protected and/or the
arrangement of the
microenvironment, e.g., the microenvironment may include interior regions 116
(FIG. 2) not in
fluid communication with one another, more than one corrosion inhibitor source
612 may be
used. Corrosion inhibitor source 612 may optionally be provided with a seal
620 or other means
for opening apertures 618 to allow corrosion inhibitor 604 to escape. Seal 620
may be removed
just prior to corrosion inhibitor source 612 being placed into the
microenvironment.
[00511 Like cover 300 of FIG. 4, discussed above, that contains radar-
influencing layer 308,
any of the embodiments of cover 600 shown in FIGS. 8A-D may contain a radar-
influencing
layer containing one or more radar-reflecting and/or radar-absorbing
materials, such as materials
310, 312 mentioned above in connection with cover 300. Such a radar-
influencing materials
may be located in any of layers 602, 606, 608, or coating 610, or may be
provided in a layer
separate from these layers and located on either side of water-vapor-permeable
layer 602. Those
skilled in the art will readily understand how one or more radar influencing
materials may be
incorporated into cover 600 such that a detailed explanation need not be
provided in detail
herein.
100521 In each of the above exemplary embodiments of the cover system of the
present
invention, the extent of the various layers was not described with
particularity. For example, the
discussion of moisture absorbing layer 206 in the context of cover 200 and
FIG. 3 directed to this
embodiment did not particularly indicate whether or not the moisture-absorbing
layer is
coextensive with liquid-permeable layer 202 and/or liquid-impermeable layer
204. As those
skilled in the art will appreciate, the various layers of a cover according to
the present invention
may be coextensive with the area of the cover, but may also be smaller in area
than the cover.
For example, in FIG. 3 just mentioned, moisture-absorbing layer 206 and/or
liquid-permeable
layer 202 may extend over only a portion of liquid-impermeable layer 204. In
addition,
moisture-absorbing layer 206 and/or liquid-permeable layer 202 may be
"discretized" so as to be
present in certain spaced locations that may or may not correspond to
particular locations, e.g.,
flat water-retaining surfaces, of the object to be covered.
CA 02736635 2012-05-28
[00531 Although those skilled in the art will immediately recognize the
variety of arrangements
that these discretized locations may have, examples of "regular" arrangements
include a
"window-pane" arrangement, wherein rectangular regions of moisture-absorbing
and/or liquid-
permeable layers are separated by regions where the materials/characteristics
of these layers are
not present, and a "striped" arrangement, wherein the cover includes strips
where the
materials/characteristics of the moisture-absorbing and/or liquid-permeable
layers are
alternatingly present and not present. This type of discretization of the
moisture-absorbing and
liquid-permeable layers is applicable to any embodiment containing such
layers. Other layers,
such as a separate corrosion inhibitor layer or a radar-influencing layer, may
be discretized in a
similar manner in any embodiment containing such layer(s). Of course,
alternatively these
layers, too, may be coextensive with the cover. Similarly, in embodiments
wherein a corrosion
inhibitor, radar-influencing material, or other material is incorporated into
one or more of the
liquid-impermeable, moisture-absorbing, and/or liquid-permeable layers, as the
case may be, the
corrosion inhibitor or radar-influencing material may be placed in discretized
locations with
respect to the area of the corresponding cover.
21
4177079 vl
