Note: Descriptions are shown in the official language in which they were submitted.
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FLEXIBLE INSULATING STRUCTURES AND
METHODS OF MAKING AND USING SAME
BACKGROUND OF THE INVENTION
[00011 Many applications benefit from using materials that are both
relatively
light and good thermal insulators. Aerogels, for example, typically exhibit
very low
density and very low thermal conductivity and are found in a variety of
insulating
articles. Aerogel blankets, for example, can be utilized in pipe, aircraft,
automotive,
building, clothing, footwear, and other types of insulations.
[0002] U.S. Patent No. 7,399,439, issued to Lee, etal. on July 15, 2008,
describes
aerogel blankets that are formed using a process for continuously casting
solvent filled gel
sheet material in which a sol and a gel inducing agent are continuously
combined to form a
catalyzed sol. A gel sheet is produced by dispensing the catalyzed sol onto a
moving element
at a predetermined rate effective to allow gelation to occur to the catalyzed
sol on the moving
element. The solvent is extracted by supercritical fluid drying.
[0003] U.S. Patent No. 6,989,123 issued to Lee, et al. on January 24, 2006,
describes
aerogel blankets produced using a process for casting gel sheets, the process
including:
providing a quantity of fibrous batting material; introducing a quantity of
impermeable
material to separate the quantity of fibrous batting material into a fiber-
roll preform having a
plurality of fibrous layers; infusing a quantity of catalyzed sol into the
fiber-roll preform;
gelling the catalyzed sol in the fiber-roll preform; removing the impermeable
material to
leave remaining a gel material; introducing a quantity of permeable material
to separate the
gel material into a plurality of layers. The interstitial solvent phase
typically is removed by
supercritical fluids extraction.
[0004] U.S. Patent No. 7,635,411, issued to Rouanet et al., on December 22,
2009,
describes blankets produced by preparing an aqueous slurry, which includes
hydrophobic
aerogel particles, fibers, and at least one
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wetting agent. Preferably, the hydrophobic aerogel particles form an intimate
mixture with
the fibers, at least temporarily. The mixture can then be substantially
dewatered,
compressed, dried to form a web which can be further processed, e.g., by
calendaring, to
form a blanket.
SUMMARY OF THE INVENTION
[0005] Considering the vast number of applications requiring thermal
insulation, a
need continues to exist for flexible insulating articles that have attractive
properties and for
methods for producing and using them.
[0006] In one embodiment, a flexible insulating structure includes a
batting and a
mixture of aerogel-containing particles and a binder. The aerogel-containing
particles
impregnate at least one layer of the batting.
[0007] In another embodiment, a method for preparing a flexible insulating
structure
comprises applying a mixture including aerogel-containing particles and a
binder to a
batting having one or more batting layers; and drying or allowing the binder
to dry, thereby
forming the flexible insulating structure.
[0008] Articles described herein have low thermal conductivity and present
many
advantages. For instance, the flexible insulating structure can have improved
flame and
fire properties and can withstand elevated temperatures. In many
implementations, the
structure displays good performance under compressive loads and can have
acoustic and/or
electrical insulation characteristics.
[0009] Methods for fabricating the flexible insulating structure described
herein use
widely available materials, are relatively straightforward and amenable to
scale-up for
industrial manufacturing processes, using, for instance, air-laid and/or roll
to roll
technology. Use of prefabricated aerogel particles obviates the need for in
situ gelling
required by many existing methods for preparing aerogel blankets. Batting
selection
provides opportunities and flexibility to fine tune properties such as thermal
conductivity,
behavior at elevated temperatures, behavior under compressive load, tensile
strength,
thickness and others.
2
[0009a] In
accordance with another aspect of the present invention, there is provided a
method for preparing a flexible insulating structure, the method comprising:
applying a
mixture including aerogel-containing particles and a binder to a flexible
batting having one
or more batting layers, the aerogel-containing particles impregnating at least
one layer of the
batting, wherein the binder comprises an inorganic material; and drying or
allowing the
binder to dry, thereby forming the flexible insulating structure.
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[0010] Other advantages associated with aspects of the invention relate to
flexibility
of addition of other additives to modify, e.g., improve, fire characteristics,
thermal insulation
performance at high and/or low, e.g., cryogenic, temperatures, water and water
vapor
sorption characteristics and so forth.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] In the accompanying drawings, reference characters refer to the
same parts
throughout the different views. The drawings are not necessarily to scale;
emphasis has
instead been placed upon illustrating the principles of the invention. Of the
drawings:
[0012] FIG. 1 is a photograph of an insulating flexible material according
to one
aspect of the invention.
[0013] FIGS. 2A, 2B and 2C illustrate the formation of a sandwich
structure
including a total of two fabric layers.
[0014] FIGS. 3A, 3B and 3C illustrate the formation of a sandwich
structure
including a total of four fabric layers.
DETAILED DESCRIPTION OF TIIE PREFERRED EMBODIMENTS
[0015] The above and other features of the invention including various
details of
construction and combinations of parts, and other advantages, will now be more
particularly
described with reference to the accompanying drawings. It will be understood
that the
particular method and device embodying the invention are shown by way of
illustration. The
principles and features of this invention may be employed in various and
numerous
embodiments.
[0016] The invention generally relates to an insulation article
(structure) that
includes a fiber component, generally in the form of one or more layers, and a
nanoporous
material, e.g., aerogel-containing particles, to methods for producing and to
methods for
using the article or structure.
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[0017] Generally, the layers are in the form of a lofty fibrous structure
(i.e. batting),
and in many cases are non-woven. In non-woven materials, fibers are held
together by
mechanical interlocking in a random web (mesh) or mat; bonding can be achieved
using a
medium such as, for example, starch, glue, casein, rubber, latex, synthetic
resins, cellulose
derivatives, by fusing of the fibers and/or by other means, e.g., as known in
the art. In
some cases, non-woven layers are made of crimped fibers that can range in
length from
about 0.75 to about 4.5 inches. The diameter of the fibers can be in within
the range of
about 0.1 to about 10,000 microns. Other fiber dimensions can be selected.
[0018] Woven fiber layers, using leno, plain or other weaving techniques,
e.g., as
known in the art, also can be employed.
[0019] In some embodiments, the batting has insulating properties. For
instance, the
batting can have a thermal conductivity no greater than about 80mW/m-K at 23
C, e.g.,
within the range of from about 20 mW/m-K to about 60mW/m-K, in many cases
within the
range of from about 25mW/m-K to about 50mW/m-K.
[0020] In other embodiments, the batting is suitable for high temperature
applications.
For example, the batting employed can withstand temperatures above about 200
C, for
instance, above 300 C, and even above 600 C without degradation. In other
embodiments,
the batting has flame and/or fire resistance, low flame propagation, desirable
surface
burning characteristics and so forth.
[0021] The batting can be flexible and, in specific examples, it is
provided in rolled
up fashion.
[0022] The batting can be made from any suitable material such as, for
example,
metal oxide fibers such as glass fibers, mineral wool fibers, e.g., stone or
slag fibers,
biosoluble ceramic fibers, carbon fibers, polymer-based fibers, e.g.,
polyester, aramid,
polyolefin, polyethylene terephthalate, polymer blends, co-polymers and so
forth, metallic
fibers, cellulose fibers, plant-derived fibers, other suitable fibers or
combinations of fibers.
[0023] In specific implementations the batting is made in whole or in part
of glass
fibers, using, for instance: A-glass (a high-alkali glass containing 25% soda
and lime,
offering good resistance to chemicals, but relatively low electrical
properties); C-glass (a
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special mixture with high chemical resistance); E-glass ( electrical grade
with low alkali
content); S-glass (a high-strength glass with a 33% higher tensile strength
than E-glass); D-
glass (a low dielectric constant material with superior electrical properties
but lesser
mechanical properties relative to E-or S-glass); or othcr types of glass
fibers, e.g., as
known in the art.
[0024] In other specific implementations, the batting consists of, consists
essentially
of or comprises an insulating synthetic polymeric material such as, for
example,
Thinsulate' ", manufactured by 3M Corporation and advertised as providing 1 to
1.5 times
the insulation of duck down; or PrimaLoft (a registered trademark of the
Albany
International Corporation), a material based on synthetic microfibers and
often a viable
alternative to goose down. In many cases, polymeric materials used in battings
include
polyethylene terephthalate or mixtures of polyethylenene therephthalate and
polypropylene. In other cases, the batting polymeric materials include
polyethylene
terephthalate-polyethylene isophthalate copolymer and/or acrylic. Other
polymers, e.g.,
polyesters, polymer blends, copolymers and so forth can be employed to form
the batting.
[0025] The batting material can be characterized by its density. Suitable
batting
materials can have a density within the range of from about 1 kg/m3 to about
20 kg/m3,
e.g., 4 kg/m3. Web or mesh-like batting, such as, for example, those made of
fiberglass,
can be characterized by mesh numbers, as known in the art, or in other ways
suitable for
describing the (average) opening size present in the web. Typically, larger
mesh numbers
indicate smaller openings and smaller mesh numbers indicate larger openings.
[0026] Thickness and weight are other properties typically specified for a
particular
batting. For instance, the batting layer can have a thickness suitable to a
desired
application. In specific examples, the batting can be as thin as about 0.5 mm
or as thick as
about 110 mm. In specific examples, the batting is 4, 8, 10, 20, 30, 40, 50,
60, 70, 80, 90,
100 or 102 mm. Thinner battings can be easily rolled, for instance they can be
wrapped
around smaller radii, while thicker ones can providc added mechanical
strength, such as
tensile strength and other properties. A suitable batting layer can have a
weight of, for
example, at least 50 g/m2, e.g., 100 g/m2, 150 g/m2, 200 g/m2, 250 g/m2 or
even higher.
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[0027] Provided as an illustrative example, Table 1 shows the properties of
several
commercial grades of ThinsulateTm Ultra Lite Loft.
Table 1
Thickness (cm) Weight (g/m2) Density (kg/m3)
FX100 0.55 105 19.1
LL250 6.4 250 3.9
US100 1.07 128 12.0
US150 1.62 180 11.1
US200 2.14 233 10.9
[0028] The batting can be made of two or more layers, arranged, for example
in multi-
ply fashion. In many implementations, the multiple layers are all made of
essentially the
same material and can be the same or different with respect to layer
thickness, density,
mesh numbers, and/or other batting-related parameters. Layers manufactured
from
different materials also can be utilized, and such layers can have the same or
different layer
thickness, density, mesh numbers, and/or other batting-related parameters.
[0029] At least one of the layers present in the structure described herein
contains a
nanoporous material. As used herein, the term "nanoporous" refers to a
material having
pores that are smaller than about 1 micron, e.g., less than 0.1 microns.
Examples of
suitable nanoporous materials include, but are not limited to, oxides of a
metal such as, for
instance, silicon, aluminum, zirconium, titanium, hafnium, vanadium, yttrium
and others,
and/or mixtures thereof.
[0030] In an exemplary embodiment the nanoporous material is an aerogel.
Aerogels
arc low density porous solids that have a large intraparticle pore volume and
typically arc
produced by removing pore liquid from a wet gel. However, the drying process
can be
complicated by capillary forces in the gel pores, which can give rise to gel
shrinkage or
densification. In one manufacturing approach, collapse of the three
dimensional structure
is essentially eliminated by using supercritical drying. A wet gel also can be
dried using
ambient pressure, also referred to as non-supercritical drying process. When
applied, for
instance, to a silica-based wet gel, surface modification, e.g., end-capping,
carried out prior
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to drying, prevents permanent shrinkage in the dried product. The gel can
still shrink during
drying but springs back recovering its former porosity.
[0031] Product referred to as "xerogel" also is obtained from wet gels from
which the
liquid has been removed. The term often designates a dry gel compressed by
capillary forces
during drying, characterized by permanent changes and collapse of the solid
network.
[0032] For convenience, the term "aerogel" is used herein in a general
sense, referring
to both "aerogels" and "xerogels".
[0033] Aerogels typically have low bulk densities (about 0.15 g/cm3 or
less, in many
instances about 0.03 to 0.3 g/ cm3), very high surface areas (generally from
about 300 to
about 1,000 square meters per gram (m2/g) and higher, for example from about
600 to about
1000 m2/g), high porosity (about 90% and greater, e.g., greater than about
95%), and a
relatively large pore volume (e.g., about 3 milliliter per gram (mL/g), for
example, about 3.5
mL/g and higher, for instance, 7 mL/g). Aerogels can have a nanoporous
structure with
pores smaller than 1 micron (1,tm). Often, aerogels have a mean pore diameter
of about 20
nanometers (nm). The combination of these properties in an amorphous structure
gives the
lowest thermal conductivity values (e.g., 9 to 16 mW/m-K, at a mean
temperature of 37 C
and 1 atmosphere of pressure) for any coherent solid material. Aerogels can be
nearly
transparent or translucent, scattering blue light, or can be opaque.
[0034] A common type of aerogel is silica-based. Aerogels based on oxides
of metals
other than silicon, e.g., aluminum, zirconium, titanium, hafnium, vanadium,
yttrium and
others, or mixtures thereof can be utilized as well.
[0035] Also known are organic aerogels, e.g., resorcinol or melamine
combined with
formaldehyde, dendretic polymers, and so forth, and the invention also could
be practiced
using these materials.
[0036] Suitable aerogel materials and processes for their preparation are
described, for
example, in U.S. Patent Application No. 2001/0034375 Al to Schwertfeger et
al., published
on October 25, 2001.
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[0037] In many implementations, the aerogel employed is hydrophobic. As
used
herein, the terms "hydrophobic" and "hydrophobized" refer to partially as well
as to
completely hydrophobized aerogel. The hydrophobicity of a partially
hydrophobized aerogel
can be further increased. In completely hydrophobized aerogels, a maximum
degree of
coverage is reached and essentially all chemically attainable groups are
modified.
[0038] Hydrophobicity can be determined by methods known in the art, such
as, for
example, contact angle measurements or by methanol (Me0H) wettability. A
discussion of
hydrophobicity in relation to aerogels is found, for example, in U.S. Patent
No. 6,709,600 B2
issued to Hrubesh et al. on March 23, 2004.
[0039] Hydrophobic aerogels can be produced by using hydrophobizing agents,
e.g.,
silylating agents, halogen- and in particular fluorine-containing compounds
such as fluorine-
containing alkoxysilanes or alkoxysiloxanes, e.g.,
trifluoropropyltrimethoxysilane
(TFPTMOS), and other hydrophobizing compounds known in the art.
[0040] Silylating compounds such as, for instance, silanes, halosilanes,
haloalkylsilanes, alkoxysilanes, alkoxyalkylsilanes, alkoxyhalosilanes,
disiloxanes,
disilazanes and others are often utilized. Examples of suitable silylating
agents include, but
are not limited to diethyldichlorosilane, allylmethyldichlorosilane,
ethylphenyldichlorosilane,
phenylethyldiethoxysilane, trimethylalkoxysilanes, e.g.,
trimethylbutoxysilane, 3,3,3-
trifluoropropylmethyldichlorosilane, symdiphenyltetramethyldisiloxane,
trivinyltrimethylcyclotrisiloxane, hexaethyldisiloxane,
pentylmethyldichlorosilane,
divinyldipropoxysilane, vinyldimethylchlorosilane, vinylmethyldichlorosilane,
vinyldimethylmethoxysilane, trimethylchlorosilane, hexamethyldisiloxane,
hexenylmethyldichlorosilane, hexenyldimethylchlorosilane,
dimethylchlorosilane,
dimethyldichorosilane, mercaptopropylmethyldimethoxysilane, bis {3-
(triethoxysily0propylltetrasulfidc, hexamethyldisilazane and combinations
thereof.
[0041] Hydrophobizing agents can be used during the formation of aerogels
and/or in
subsequent processing steps, e.g., surface treatment.
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[0042] In some examples, the aerogel has a hydrophilic surface or shell
obtained, for
example, by treating hydrophobic aerogel with a surface active agent, also
referred to
herein as surfactant, dispersant or wetting agent.
[0043] Increasing the amount of surfactant tends to increase the depth to
which the
aqueous phase can penetrate and thus the thickness of the hydrophilic coating
surrounding
the hydrophobic aerogel core.
[0044] The insulating structure described herein can include additives such
as fibers,
opacifiers, color pigments, dyes or mixtures and, in some cases, these
additives are present
in the aerogel component. For instance, a silica aerogel can be prepared to
contain fibers
and/or one or more metals or compounds thereof. Specific examples include
aluminum,
tin, titanium, zirconium or other non-siliceous metals, and oxides thereof.
Non-limiting
examples of opacifiers include carbon black, titanium dioxide, silicon
carbide, zirconium
silicate, and mixtures thereof. Additives can be provided in any suitable
amounts, e.g.,
depending on desired properties and/or specific application.
[0045] Generally, the nanoporous material employed, e.g. a silica aerogel
such as
described herein, is prefabricated, as opposed to being formed in situ, during
the
manufacture of the insulation structure. Specific embodiments, for example,
utilize
aerogel-containing particles, e.g., granules, pellets, beads, powders or other
types of
aerogel-containing particulate material. Suitable particulate materials can
consist, consist
essentially of or comprise aerogel, e.g., a silica-based aerogel.
[0046] The particles can have any particle size suitable for an intended
application.
For instance, the aerogel particles can be within the range of from about 0.01
microns (gm)
to about 10.0 millimeters (mm) and can have, for example, a mean particle size
in the
range of 0.3 to 5.0 mm. In many examples, the average particle size is within
the range of
from about 1 micron to 100 gm, for instance within the range of 8-10 gm. Other
suitable
particle sizes are within the range of from about 0.3 to about 1 gm; from
about 1 to about
3, 5 or 8 gm; from about 10 to about 15 or about 20 gm; from about 20 to about
35 gm; or
from about 35 to about 50 gm. Combinations of particle sizes also can be used.
In specific
examples, the particle size is selected considering factors such as desired
degree of
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penetration through the batting, the type of batting utilized, size of mesh
openings in the
batting layer(s), batting or batting layer thickness, and so forth.
[0047] Examples of commercially available aerogel materials in particulate
form are
those supplied under the tradename of Nanogel by Cabot Corporation,
Billerica,
Massachusetts. Nanogelt aerogel granules have high surface area, are greater
than about
90% porous and are available in a wide range of particle sizes such as, for
example, the
ranges described above. Specific grades of translucent Nanogele aerogel
include, for
instance, those designated as TLD302, TLD301, TLD201 or TED100; specific
grades of IR-
opacified Nanogelt aerogel include, e.g., those under the designation of
RGD303 or
CBTLD103; specific grades of opaque Nanogele aerogel include, for instance,
those
designated as 0GD303.
[0048] The aerogel-containing material, preferably in particulate form, can
also be
derived from a monolithic aerogel or aerogel-based composites, sheets,
blankets and so forth.
For example, pieces of such aerogel materials can be obtained by breaking
down, chopping,
comminuting or by other suitable techniques through which aerogel particles
can be obtained
from aerogel monoliths, composites, blankets, sheets and other such
precursors.
[0049] Examples of materials that can be processed to produce particles or
pieces of
aerogel-containing material include aerogel-based composite materials, such as
those
containing aerogel and fibers (e.g., fiber-reinforced aerogels) and,
optionally, at least one
binder. The fibers can have any suitable structure. For example, the fibers
can be oriented in
a parallel direction, an orthogonal direction, in a common direction or a
random direction.
There can be one or more types of fibers. The fibers can be different in terms
of their
composition, size or structure. In the composite, the one type of fibers can
be in different
dimensions (length and diameter) and their orientation can be different. For
example long
fibers are in plane aligned whereas smaller fibres are randomly distributed.
Specific
examples are described, for instance, in U.S. Patent No. 6,887,563, issued on
May 3, 2005 to
Frank et al. Other examples include at least one aerogel and at least one
syntactic foam. The
aerogel can be coated to prevent intrusion of the polymer into the pores of
the aerogel, as
described, for instance in International Publication No. WO 2007047970, with
the title
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Aerogel Based Composites. In yet other examples, the aerogel can derive from a
blanket,
e.g., arrangements in which blanket sheets are laminated together to form a
multilayer
structures. Described in U.S. Patent No. 5,789,075, issued on August 4, 1998
to Frank et al.,
are cracked monoliths and these also can serve as suitable precursor in
producing the self
supporting rigid composite disclosed herein. In further examples the aerogel
employed
includes a composite of an aerogel material, a binder and at least one fiber
material as
described, for instance, in U.S. Patent No. 6,887,563, issued on May 3, 2005
to Frank et al.
Other suitable examples of aerogel material that can be used are fiber-
web/aerogel
composites that include bicomponent fibers as disclosed in U.S. Patent No.
5,786,059 issued
on July 28, 1998 to Frank et al. The aerogel particles also can be derived
from sheets or
blankets produced from wet gel structures, as described, for instance, in U.S.
Patent
Application Publication Nos, 2005/0046086 Al, published March 3, 2005, and
2005/0167891 Al, published on August 4, 2005, both to Lee et al. Commercially,
aerogel-
type blankets or sheets are available from Cabot Corporation, Billerica, Mass.
or from Aspen
Aerogels, Inc., Northborough, Mass.
[0050] Combinations of
aerogel-containing materials also can be employed. For
instance, different types of aerogel-containing materials e.g., combinations
or mixtures of
granular aerogels having different particle sizes, acoustic and/or light
transmitting properties.
Blends of aerogel with other materials, such as, for instance, non aerogel
nanoporous metal
oxides, e.g., silica, including but not limited to fumed silica, colloidal
silica or precipitated
silica, carbon black, titanium dioxide, perlite, microspheres such as glass,
ceramic or
polymeric microspheres, silicates, copolymers, tensides, mineral powders,
fibers, and so
forth also can be used.
[0051] The nanoporous
material, e.g., in the form of pre-fabricated aerogel particles,
typically is provided in combination with other components. In many
embodiments, the
nanoporous material, e.g., pre-prepared aerogel-containing particles, is
provided in
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combination with a binder. In many examples, the binder is a material that,
under certain
conditions, sets, hardens or becomes cured. For convenience, these and similar
such
processes are referred to herein as "drying". Preferably, these "drying"
processes are
irreversible.
[0052] In many implementations, the binder comprises, consists essentially
of or
consists of gypsum, a material based on calcium sulfate hemihydrate
(CaSO4=0.5H20).
Typically, the calcined gypsum (calcium sulfate) is used in an aqueous slurry
form; drying
induced crystallization causes the formation of crystals of calcium sulfate
which interlock
to provide mechanical properties to the binder. In case of lime plaster (based
on calcium
oxide), the aqueous slurry forms calcium hydroxide which under the influence
of carbon
dioxide in the atmosphere forms calcium carbonate.
[0053] Other suitable binders comprise, consist essentially of or consist
of one or
more materials such as, for instance, cement, lime, mixed magnesium salts,
silicates, e.g.,
sodium silicate, plaster and/or other inorganic or inorganic-containing
compositions.
Cements, for example, often include limestone, clay and other ingredients,
e.g., hydrous
silicates of alumina. Hydraulic cements, for instance, are materials that set
and harden after
being combined with water, as a result of chemical reactions with the mixing
water, and
that, after hardening, retain strength and stability even under water. The key
requirement
for this strength and stability is that the hydrates formed on immediate
reaction with water
be essentially insoluble in water. Setting and hardening of hydraulic cements
is caused by
the formation of water-containing compounds, which are produced as a result of
reactions
between cement components and water. The reaction and the reaction products
are
referred to as hydration and hydrates or hydrate phases, respectively. As a
result of the
immediate start of the reactions, stiffening can be observed which is
initially slight but
which increases with time. The point at which the stiffening reaches a certain
level is
referred to as the start of setting. Further consolidation is called setting,
after which the
hardening phase begins. The compressive strength of the material then grows
steadily,
over a period that ranges from a few days in the case of "ultra-rapid-
hardening" cements to
several years in the case of ordinary cements.
[0054] The binder can also consist of, consist essentially of or comprise
one or more
organic materials such as, for example, acrylates, other latex compositions,
epoxy
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polymers, polyurethane, polyethylene polypropylene and polytetrafluoroethylene
polymers,
e.g., those available under the designation of Teflonni. Many organic binders
can become
set or hardened through polymerization or curing processes, e.g., as known in
the art.
[0055] The binder can be combined with the aerogel component
in any suitable
ratio. Examples include but are not limited to aerogel to binder weight ratios
within the
range of 100 to 5 to 100 to 30. Other ratios of aerogel to binder can be
selected. In specific
examples, the aerogel to binder weight ratios are 100:10; 100:15; 100:20 or
100:25.
[00563 Some aspects of the invention employ one or more
surfactants. Suitable
surfactant that can be used in conjunction with the aerogel (e.g., aerogel
particles) and binder
can be ionic (anionic and cationic) surfactants, amphoteric surfactants,
nonionic surfactants,
high molecular surfactants, high molecular compounds and so forth.
Combinations of
different types of surfactants also can be utilized.
[00571 Anionic surfactants can include, for example, alkyl
sulfates and higher alkyl
ether sulfates, more specifically, ammonium lauryl sulfate, and sodium
polyoxyethylene
lauryl ether sulfate. Cationic surfactants include, for instance, aliphatic
ammonium salts and
amine salts, more specifically, alkyl trimethylammonium, and polyoxyethylene
alkyl amine,
for example. Amphoteric surfactants may be of betain type, such as alkyl
dimethyl betain, or
of oxido type, such as alkyl dimethyl amine oxido, for example. Nonionic
surfactants
include glycerol fatty acid ester, propylene glycol fatty acid ester, sorbitan
fatty acid ester,
polyoxyethylene sorbitan fatty acid ester, tetraoleic acid polyoxyethylene
sorbitol,
polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether,
polyoxyethylene
polyoxypropylene glycol, polyoxyethylene polyoxypropylene alkyl ether,
polyethylene glycol
fatty acid ester, higher fatty acid alcohol ester, polyhydric alcohol fatty
acid ester, and others
[0058] Specific examples of surfactants that can be utilized
include but are not
limited to PluronicTM P84, PE6100, PE6800, L121, Emulan'm EL, Lutensollm FSA
10,
Lutensoirm XP89 all from BASF, MP5490 from Michelmann, AEROSOL TM OT (sodium
di-
2-ethylhexylsulfosuccinite), BARLOXTm 121 (a branched alkyldimethylamine
oxide), LAS
(linear alkylbenzene sulfonates) and TRITON TM 100 (octylphenoxypolyethoxy(9-
,
13
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10)ethanol), TWEENTm surfactants like TWEENTm 100 surfactant, and BASF
pluronie
surfactants and others. A general class is glycols, alkoxylates
polyoxyalkylene fatty ethers,
such as polyoxyethylene fatty ethers, sorbitan esters, mono and diglycerides,
polyoxyethylene
sorbitol esters, polymeric surfactants like I lypermen polymer surfactants,
sodium coco-PG-
dimonium chloride phosphate and coamidopropyl PG-dimonium chloride phosphate,
phosphate esters, polyoxyethylene (POE) fatty acid esters, Renex nonionic
surfactants
(nonionic esters formed by reaction of ethylene oxide and unsaturated fatty
acids and
heterocyclic resin acids.), alcohol ethoxylates, alcohol alkoxylates, ethylene
oxide/propylene
oxide block copolymers, polyoxyethylene derivatives of sorbitan esters or
combinations
thereof.
[0059] The specific amount of surfactant can be chosen by considering
factors such
as particle size, surfactant type and/or other suitable criteria. In many
cases, the weight ratio
of the surfactant to the amount of aerogel-containing particles and binder is
at least about
1:100, e.g., from about 10:100 to about 30:100. Exemplary ratios that can be
utilized include
5:100; 15:100; 20:100 or 25:100; 35:100.
[0060] Other ingredients can be present. As used herein, the terms
"another"
ingredient", "other ingredients" or "additional ingredient(s)" refer to
compounds or materials
that are external to the pre-prepared nanoporous material (e.g., aerogel-
containing particles)
employed. For example, if Nanogel aerogel particles are utilized, the term
"other
ingredient" refers to ingredients that can be combined with the Nanogel
aerogel particles
being used, rather than to ingredients already present in or at the surface of
the Nanogel
aerogel particles. These other ingredients can be used to provide
reinforcement to a final
product, to wet the outer surface of aerogel particles, to increase adhesion
to a batting
substrate, rendering the composition more likely to stick to a particular
batting material, to
provide or enhance other characteristics desired in the composition or the
finished insulating
article, or for other reasons.
[0061] Examples of other ingredients that can be employed include but are
not
limited to opacifiers, viscosity regulators, curing agents, agents that
enhance or slow down
the rate at which the binder hardens, agents or materials that promote
mechanical strength,
viscosity regulators, pH modifiers, plasticizers, lubricants, reinforcements,
fire retardants
(such as, for example, halogen containing compounds, bromates, borates,
aluminum tri-
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hydroxide, magnesium hydroxide, other oxides and/or other compounds known in
the field
of fibers, plastics, and composites), and others. Combinations of other
ingredients also can
be utilized.
[0062] In specific examples, the other ingredients are selected from
fibers, fumed
silica, colloidal silica or precipitated silica, opacifiers, including but not
limited to carbon
black and titanium dioxide, perlite, microspheres such as glass or polymeric
microspheres,
silicates, e.g., calcium silicate, copolymers, tensides, mineral powder, film
building
components, surfactants, and any combination thereof
[0063] Fibers, for example, typically have elongated, e.g. cylindrical,
shapes with
length to diameter aspect ratios that are greater than 1, preferably greater
than 5, more
preferably greater than 8. In many examples suitable fibers have a length to
diameter ratio
of at least 20. The fibers can be woven, non-woven, chopped, or continuous.
Fibers can
be mono-component, bi-component, e.g., including a core made of one material
and a
sheath made of another material, or multi-component. Fibers may be hollow or
solid and
may have a cross-section that is flat, rectangular, cylindrical or irregular.
The fibers may
be loose, chopped, bundled, or connected together in a web or scrim.
[0064] Examples of fibers that can be added include mineral wool fibers,
e.g., glass,
stone or slag fibers; bio-soluble ceramic fibers; or a woven, non-woven or
chopped form of
continuously made glass or stone fiber. Carbon fibers, polymer-based fibers,
metallic, e.g.,
steel, fibers, cellulose fibers, plant-derived, e.g., cotton, wood or hemp
fibers.
Combinations of fibers also can be used.
[0065] Amounts of other ingredients added may depend on specific
applications and
other factors. Thus other ingredients can be present, in amounts greater than
0 weight % of
the total weight of the mixture, e.g., greater than 2 weight %, for example
greater than 5
weight %, greater than 10 weight %, greater than 15 weight %, greater than 20
weight % or
greater than 25 weight %. They can be present in the composition in amounts
that are less
than about 90 % by weight, e.g., less than about 75 weight % or less than 50%
by weight.
[0066] Dry blending or wet mixing techniques can be utilized to combine the
nanoporous material (such as pre-prepared aerogel-containing particles),
binder, and, if
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used, surfactant and/or other ingredients. Two, more or all components can be
added
simultaneously. Ingredients also can be combined sequentially, using any
suitable order.
[0067] In many embodiments, one or more of the starting materials contain a
liquid
and mixing produces a slurry. In other embodiments, dry starting materials can
be
combined with a liquid, in any suitable order, and mixing can be used to
generate a slurry.
[0068] Mixing can be carried out manually (e.g., by manual stirring or
shaking). In
specific implementations, the slurry is formed with the aid of a blender or
mixer, such as,
for example, a cement mixer, a hand-held or an industrial impeller. Ribbon
blender,
double ribbon blades, planetary mixers and other suitable mixing devices,
e.g., as known in
the art, also can be utilized. In some cases, blade design and/or properties,
e.g., increased
blade sharpness, can reduce the amount of time necessary to complete the
mixing process
and, in some cases, the properties of the final product. In specific examples,
light particles,
e.g., aerogel particles, are forced into a liquid phase. In other examples,
liquid droplets are
lifted to the lighter particles.
[0069] Parameters such as mixing speed, temperature, degree of shear, order
and/or
addition rate of the liquid and/or solid materials, and others can be adjusted
and may
depend on the scale of the operation, the physical and/or chemical nature of
the
compounds, and so forth.
[0070] Mixing techniques can be selected to change (typically reduce) the
absolute
size of the aerogel particles. In specific examples, the mixing technique
selected provides
enough shear to reduce the size of at least some of the aerogel particles,
e.g., to improve
penetration of the aerogel material into and/or through the batting being
utilized. In other
examples, e.g., in cases in which the starting aerogel particles have a
particle size suitable
for a particular batting, a more gentle mixing technique can be utilized. In
yet other
examples, the mixing technique is selected to modify the size distribution of
the aerogel
particles. In turn, a change in the particle size distribution can be utilized
to provide
improved particle packing efficiency.
[0071] Mixing can be conducted at room temperature or at other suitable
temperatures. Typically, the components are combined in ambient air but
special gas
atmospheres and/or pressures can be provided.
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[0072] In many cases, the slurry is aqueous, i.e., its liquid phase
contains more than
50% volume percent water. Non-aqueous slurries also can be used. Such non-
aqueous
slurries can contain one or more organic compounds, such as, for example
organic
solvents, surfactants, thinners, and so forth. Non-aqueous slurries can
contain water in an
amount of from about 0 to about 50 volume percent, for example, 5, 10, 15, 20,
25, 30, 35,
40, 45 or 49 volume %.
[0073] The slurry viscosity is selected considering factors such as, for
example, the
type of batting material utilized, batting thickness, number of batting layers
being treated
with the slurry, techniques employed to treat the batting with the slurry and
so forth.
Denser and/or thicker webs, for instance, may benefit from use of low
viscosity slurries,
whereas more viscous slurries can be used in conjunction with thin and/or open
webs. In
many cases, the slurry has a viscosity within the range of from about 2,000
centipoise (cp)
to about 100,000 cp, for example, 10,000 cp; 20,000cp; 30,000 cp; 40,000 cp;
50,000cp;
60,000 cp; 70,000 co; 80,000 cp; or 90,000 cp.
[0074] The batting can be treated with the slurry by various processes. In
many
embodiments, the batting layer or layers are impregnated with the slun-y. In
some
implementations, the process selected provides penetration of at least one of
the batting
layers utilized. In other implementations, the process provides penetration
through two or
more batting layers. In one example, the slurry is applied to a first batting
layer, which is
then covered by a second batting layer. Slurry is then applied to the second
batting layer
and the process is continued for the desired number of layers. In further
implementation,
the method selected is suitable for scale-up or industrial processes such as,
for example,
air-laid and/or roll to roll manufacturing.
[0075] Specific techniques contemplated for applying the slurry to the
batting include
but are not limited to: dipping or immersing the batting in the slurry, e.g.,
with or without
bath agitation, pouring of the slurry over the batting, infusion, spraying or
painting of the
batting with the slurry, and/or other processes, e.g., as known in the art. It
was discovered
that soaking the batting in the slurry was particularly useful in impregnating
multi (two or
more) layered battings. In specific implementations, the soaking was conducted
in the
presence of shaking, stirring, or another suitable form of agitation for the
entire soaking
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period or for a lesser time interval. Intermittent agitation of the immersion
bath also can be
employed.
[0076] Applying the slurry to the batting can be conducted at ambient
conditions, e.g.,
room temperature and/or atmospheric pressure or at other suitable conditions.
For
instance, the batting can be treated at temperatures higher than room
temperature. Pressure
differentials can be used, for instance, to promote penetration of the slurry
through web
openings in the batting.
[0077] In many implementations, the aerogel-containing particles are
distributed
throughout the thickness of the single or multi-layered batting. Insulating
structures that
contain aerogel (or other nanoporous material) distributed throughout the
thickness of all
the batting layer(s) employed can be referred to as "impregnated" structures
or articles. In
"partially" impregnated structures, aerogel (or other nanoporous material) is
distributed
through some but not all the batting layers employed. In "painted" insulating
structures,
aerogel (or other nanoporous material) is present at one face of the structure
but does not
penetrated to the opposite face of the painted layer, e.g., to the inner face
of an outer
batting layer in a multi-layer arrangement.
[0078] The treated batting can be dried, e.g., at room temperature or at a
higher than
room temperature, using air or special atmospheres, e.g., inert gas. Drying
can be carried
out by simply allowing the slurry to dry or by using an oven, drying chamber,
gas flow
directed to the sluny-containing batting, drawing a vacuum through the treated
batting, or
any other suitable drying apparatus, e.g., as known in the art. In specific
examples, the
drying step is conducted using equipment and/or techniques suitable for a
scale-up or
industrial manufacturing process.
[0079] The structure can include additional elements. For example, one or
both
external (outer) faces of the structure described herein can be covered with a
film, foil,
coating or another type of outer layer for protection, to provide a reflective
coating, water
barrier or water vapor barrier, to form a multi-ply arrangement.
[0080] To produce such structures, one or more cover layers, made, for
example of a
film, foil, coating, or another suitable material can be affixed to one or
both outer faces of
the structure at any suitable time during or after the fabrication process.
For instance, a
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cover can be provided at an outer face of an outer batting layer, before
applying the
mixture (slurry). In other cases, the cover can be attached to an outer face
of the finished
structure. When both (outer) faces of the structure are covered, the cover
layers can be the
same or different. For example, both coatings can be made of the same water or
water
vapor barrier material. In other cases, one cover layer can be designed to
provide
protection during unrolling, while the other can be a reflective film.
[0081] The cover can be attached by any suitable means. For instance, it
can be
laminated, glued, painted, sprayed, secured by mechanical means such as
staples, fasteners,
and so forth, or otherwise bonded to an outer face of the batting or the
finished structure.
[0082] Additional elements also can be provided in the form of one or more
internal
layers made from a material other than a batting material. In one approach for
fabricating
such a structure, one or more non-batting layer is interspersed with batting
layers and the
process can be adapted to ensure that one or more of the batting layers become
impregnated with the slurry. Immersion techniques, a sequential application of
slurry to
each batting layer or other suitable methods can be utilized.
[0083] The structure can contain at least one internal non-batting layer
and at least
one cover layer.
[0084] The resulting structure (article) can be in the form of a blanket,
mat, sheet,
flexible board and the like. The structure has at least some flexibility, and
in many cases is
sufficiently flexible to make possible wrapping the structure around an
object, rolling
and/or unrolling it, bending, folding and other operations desired in aerogel-
containing
blankets or flexible composites. A photograph of an insulating flexible
material according
embodiments described herein is shown in FIG. 1.
[0085] In many cases, the flexible insulating structure described herein
has a thermal
conductivity (at 23 C and 1 atmosphere) that is no greater than about 50
milliwatts divided
by meter times degree Kelvin (mW/(m=K), e.g., no greater than about 30, for
instance no
greater than about 25 and in many cases no greater than about 23 mW/(m=K).
[0086] The structure can have other properties such as specific light
transmission
characteristics, e.g., transmit at least some visible light, acoustic
insulation properties, e.g.,
19
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sound absorbing and/or sound reflecting characteristics. The insulating
flexible structure
described herein also can have electrical insulating properties.
[0087] Properties associated with fire safety requirements such as, for
instance,
total calorific content, flames spread index, surface burning characteristics,
combustibility,
also can provided,
[0088] In many implementations, the structure is capable of withstanding
temperatures of at least I50 C, often at least 300 C, e.g., within the range
of from about
100 C to about 800 C, such as, for example, within the range of from about 200
C to about
600 C, without significant deterioration.
[0089] In many cases the structure has hydrophobic properties.
[00901 The structure can perform well under compressive load, having, for
instance, load bearing properties.
[0091] The insulating, flexible structure can be used to insulate pipes,
e.g., in pipe-
in-pipe arrangements, vessels or other industrial equipment, in buildings,
automotive, ship,
aircraft and other applications, in clothing, footwear, sporting equipment,
and so forth. In
many implementations, the structure is used in high temperature applications,
e.g., within
the range of from about 150 C to about 800 C. In one example, a method for
insulating an
object includes incorporating the flexible insulating structure in an article
containing the
object; and exposing the article to a temperature of at least 150 C, is
described herein.
EXEMPLIFICATION
Example 1
[0092] 300 g deionized water, 0.33 g of a 50% solution of PluronicTM P84
(BASF),
16.7 g of calcium sulfate hemi-hydrate (Sigma Aldrich) and 33 g TLD302 grade
Nanogel
aerogel were blended for 3 minutes using a Waring Commercial 7010G Blender
mixer from
WaringTM Products , CT, on Low setting to form a mixture (or slurry).
[0093] The mixture was poured over two kinds of synthetic microfiber
thermal
insulators, namely: ThinsulateTm 100 (from 3M) and PrimaLoft 1.8 oz (with the
backing
CA 02876691 2016-05-03
removed). After 45 minutes, examination of the samples revealed that only
water had
permeated through the PrimaLoft insulation and nothing had permeated through
the
ThinsulateTm material. It is believed that the batting in the ThinsulateTm
insulation interfered
with the penetration of aerogel particles.
Example 2
[0094] 500 g deionized water, 0.33 g of a 50% solution of Pluronicrm P84
(BASF),
16.7 g of calcium sulfate hemi-hydrate (Sigma Aldrich) and 33 g TLD302 grade
Nanogel
aerogel were blended using a WaringTM Commercial 7010G Blender on the "Low"
setting
for 3 minutes.
[0095] The mixture was poured over samples of PrimaLoft0 with the backing
removed. The PrimaLoft material was made up of 4 layers of fabric. Several
groups of
samples were studied, each layer in the samples corresponding to 1/4th of a
PrimaLoft0
fabric. Group #1 samples had one layer; Group #2 samples were in the form of
one layer
sandwich; Group # 3 samples had two layers; and Group #4 samples had a two
layer
sandwich arrangement.
[0096] In the "sandwich" arrangements, one or two layers were placed down,
the
mixture was poured over the upper surface of the bottom layer(s) and one or
two layers were
placed on top.
[0097] To illustrate, shown in FIG. 2A, for instance, is bottom fabric
layer 12. The
mixture 14, containing aerogel and binder, is added to the upper surface of
layer 12, as
shown in FIG. 2B. Fabric layer 16 is then placed on top of mixture 14,
resulting in a
sandwich structure containing two layers (12 and 16), as shown in FIG. 2C.
[0098] A sandwich structure with more than two layers can be prepared as
illustrated in FIGS. 3A through 3C. Shown in FIG. 3A are two stacked bottom
fabric layers,
specifically fabric layers 22 and 24. Mixture 14 (containing aerogel and
binder) is added
(poured) at the upper surface of fabric layer 24, as shown in FIG. 3B. The
structure is
completed by covering the top of mixture 14 with layers 26 and 28, resulting
in a sandwich
structure containing more than 2 layers (in this case a total of four layers),
as shown in FIG.
3C.
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[0099] After 24 hours, for each one of the one layer samples (Group #1),
the
mixture had permeated through the layer to the bottom. When pulled apart, the
sandwiched
one layer samples (Group #2) had an even amount of dried mixture on either
side. For the
two layer samples (Group #3) the mixture did not permeate through to the
bottom. When
pulled apart. the two layer sandwich type samples (Group #4) presented a clean
top layer
with no dried mixture.
Example 3
[0100] 500 g deionized water, 0.33 g of a 50% solution of PluronicIm P84
(BASF),
16.7 g of calcium sulfate hemi-hydrate (Sigma Aldrich) and 33 g TLD302 grade
Nanogel
aerogel (particle size in the 1.2 to 3.2mm range) were blended on Lo setting,
using a
WaringTM Commercial 7010G Blender mixer from Waring Products , CT, for 3
minutes.
[0101] Portions of the mixture were placed in plastic screw top containers
as
follows. Container #1 included mixture along with 2 one-layer pieces of
PrimaLoft ;
container #2 included mixture along with 45 2 cm x 2 cm pieces of 1 layer
thick PrimaLoft .
Both containers were shaken for 1 hour. The samples were removed and laid flat
in a mold
and allowed to dry overnight. Both approaches resulted in samples of PrimaLoft
that were
well impregnated with the Nanogel aerogel mixture.
Example 4
[0102] The mixture included the same ingredients and amounts used in
Example 3,
above, except for using grade TLD201 (particle size in the 1 to 30microns, d50
of 8-10
microns) Nanogel type aerogel (rather than the TLD302 grade of Example 3).
Blending
was carried out by hand and the mixture was shaken with one-layer large pieces
and one-
layer 2 cm x 2 cm pieces and dried overnight. The samples were found to be
well
impregnated with the aerogel containing mixture.
[0103] The TLD201 grade Nanogel aerogel had a particle size of 8-10
microns,
which was believed to be approximately the same as the sheared down particle
size obtained
using TLD302 grade Nanogel type aerogel and mechanical blending. The results
indicated
that both approaches led to well impregnated samples.
22
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Example .5
[0104] 500 g deionized water, 0.33 g ofa 50% solution of Pluronic P84
(BASF),
16.7 g of calcium sulfate herni-hydrate (Sigma Aldrich) and 33 g TLD302 grade
Nanogel0
aerogel were blended on Lo setting, using a Waring Commercial 7010G Blender
mixer from
Waring Products , CT, for 3 minutes.
[0105] The mixture was placed in a gallon plastic container. Fully layered
(all 4
PrimaLoft layers) material (with the backing removed) was cut to 6" x 6"
(Sample A).
Another piece of fully layered PrimaLoft material was cut into samples or 4
cm x 2 cm
(Sample B). All these samples were soaked in the mixture for 5 minutes, after
which they
were placed on a wire mesh funnel. Excess liquid was removed by a applying a
vacuum.
Another sample (Sample C) was made from two fully layered pieces of 6" x
6"PrimaLoft
that were soaked then placed on top of one another (for a total of 8 layers)
and allowed to
dry. All samples continued drying in an 80 C oven for 16 hours.
[0106] Thermal conductivity measurements were conducted according to the
ASTM
C518 method on a LasercornpTM Model Fox 200, from Lasercomp, MA.
[0107] Sample A had a thermal conductivity of 25.57 mW/m=K and Sample C
had a
thermal conductivity of 23.46 mW/m.K. The sample made of multiple smaller
pieces
(Sample B) was not flat enough to allow thermal conductivity measurements.
[0108] Both Samples A and C were bendable and cuttable. Sample B was more
rigid.
Other Observations
[0109] Drawing a vacuum was found to assist in the drying process but
seemed
ineffective in drawing the slurry through an insulating material such as
PrimaLoft .
[ono] Both stirring and shaking appeared beneficial in impregnating
PrirnaLoft
material, and was particularly useful when handling fully-layered PrimaLoft .
[pm] While this invention has been particularly shown and described with
references to preferred embodiments thereof, it will be understood by those
skilled in the art
that various changes in form and details may be made therein.
23
