Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
LIMITED CONDUCTION HEAT-RETAINING MATERIALS
Technical Field
Embodiments relate to heat reflecting materials, and in particular, to
materials that
offer improved heat retention or reflective properties and limit heat
conduction without
compromising breathability.
Background
Materials that provide improved insulation by reflecting body heat towards the
body
surface of a wearer often sacrifice moisture vapor transmission and result in
low
breathability. Such a reduction in moisture vapor transmission may cause the
fabric to
become damp, thereby causing discomfort and accelerating heat loss through
heat
conduction. Additionally, contact between heat-reflecting materials and the
skin or
underlying layer can undesirably allow the heat-reflecting materials to
conduct body heat
away from the skin, thus inadvertently accelerating heat loss.
Brief Description of the Drawings
Embodiments will be readily understood by the following detailed description
in
conjunction with the accompanying drawings. Embodiments are illustrated by way
of
example and not by way of limitation in the figures of the accompanying
drawings.
FIG. 1 illustrates a top view of one example of an insulating material, in
accordance
with various embodiments;
FIG. 2 illustrates a side view of the insulating material of FIG. 1, in
accordance with
various embodiments;
FIG. 3 illustrates a perspective view of the insulating material of FIG. 1, in
accordance with various embodiments;
FIG. 4 illustrates a perspective view of a second example of an insulating
material, in
accordance with various embodiments;
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FIG. 5 is a digital image of a third example of an insulating material, in
accordance
with various embodiments;
FIG. 6 is a digital image of a fourth example of an insulating material, in
accordance
with various embodiments; and
FIGS. 7A, 7B, 7C, and 7D are heat escape maps measured with an infrared (IR)
thermal imaging camera, for base fabric with vertically oriented fiber (VOF)
elements (FIG.
7A), base fabric alone (FIG. 7B), base fabric with heat-reflecting elements
(FIG. 7C); and
base fabric with heat-reflecting elements and VOF elements (FIG. 7D), in
accordance with
various embodiments.
Fig. 8 illustrates a top view of an alternative insulating material that
includes a foam-
based spacer material, in accordance with various embodiments.
Fig. 9 illustrates an example digital image of a foam-based spacer material,
in
accordance with various embodiments.
Fig. 10 illustrates a simplified top view of alternative configurations of a
foam-based
spacer material, in accordance with various embodiments.
Fig. 11 illustrates a simplified top view of an alternative configuration of a
foam-
based spacer material, in accordance with various embodiments.
Fig. 12 illustrates a digital image of a foam-based spacer material, in
accordance with
various embodiments.
Fig. 13 illustrates an example side view of an alternative insulating material
that
includes a foam-based spacer material, in accordance with various embodiments.
Fig. 14 illustrates an example side view of an alternative insulating material
that
includes a foam-based spacer material, in accordance with various embodiments.
Fig. 15 illustrates an example side view of an alternative insulating material
that
includes a foam-based spacer material, in accordance with various embodiments.
Fig. 16 illustrates example digital images of an insulating material that
includes a
foam-based spacer material, in accordance with various embodiments.
Fig. 17 depicts a thermal image of a fabric with a plurality of hexagonal foam-
based
spacer materials during a cooling cycle, in accordance with various
embodiments.
Detailed Description of Disclosed Embodiments
In the following detailed description, reference is made to the accompanying
drawings
which form a part hereof, and in which are shown by way of illustration
embodiments that
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may be practiced. It is to be understood that other embodiments may be
utilized and structural
or logical changes may be made without departing from the scope. Therefore,
the following
detailed description is not to be taken in a limiting sense, and the scope of
embodiments is
defined by the appended claims and their equivalents.
Various operations may be described as multiple discrete operations in turn,
in a
manner that may be helpful in understanding embodiments; however, the order of
description
should not be construed to imply that these operations are order dependent.
The description may use perspective-based descriptions such as up/down,
back/front,
and top/bottom. Such descriptions are merely used to facilitate the discussion
and are not
intended to restrict the application of disclosed embodiments.
The terms "coupled" and "connected," along with their derivatives, may be
used. It
should be understood that these terms are not intended as synonyms for each
other. Rather, in
particular embodiments, "connected" may be used to indicate that two or more
elements are
in direct physical contact with each other. -Coupled" may mean that two or
more elements
are in direct physical contact. However, "coupled" may also mean that two or
more elements
are not in direct contact with each other, but yet still cooperate or interact
with each other.
For the purposes of the description, a phrase in the form "A/D" or in the form
"A
and/or B" means (A), (13), or (A and B). For the purposes of the description,
a phrase in the
form -at least one of A, B, and C" means (A), (B), (C), (A and B), (A and C),
(B and C), or
(A, B and C). For the purposes of the description, a phrase in the form "(A)B"
means (B) or
(AB) that is, A is an optional element.
The description may use the terms "embodiment" or "embodiments," which may
each
refer to one or more of the same or different embodiments. Furthermore, the
terms
"comprising,- "including,- "having,- and the like, as used with respect to
embodiments, are
synonymous.
Embodiments herein provide insulating materials, for example, for body gear
and
outdoor gear, that provide improved heat reflection or retention and reduced
heat conduction,
while still providing excellent moisture vapor transmission.
In various embodiments, the insulating materials may include a base material,
such as
a fabric, having a moisture vapor transmission rate (MVTR) of at least 2000
g/m2/24h (JIS
1099 Al), such as at least 4000 g/m2/24h (JIS 1099 Al), at least 6000
g/m2/24h, or at least
8000 g/m2/24h. In various embodiments, the base material may be a mesh, foam,
or leather.
As used herein, the term "moisture vapor transmission rate (MVTR)" refers to a
measure of
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the passage of water vapor through a material, such as a fabric. The term
"breathable" is used
herein to refer to a fabric that has an MVTR at or above 2000 g/m2/24h (JIS
1099 Al). In
some embodiments, a breathable material allows for the passage of water vapor,
but not
liquid water. Although the term "breathable" is often assumed to also
encompass air
permeability, a "breathable" fabric does not necessarily have a high air
permeability.
Additional desirable characteristics of the base fabric may include water
resistance,
waterproofness, stretch, drape, and softness. In embodiments, a base material
can be a woven
or non-woven fabric, a knitted fabric, a foam, a mesh, a leather or other
material used for the
construction of an article of body gear and/or outdoor gear.
In various embodiments, a plurality of heat-reflecting elements may be coupled
to a
first side of the base material (for example, the side of the material that
faces a user's body
when the base fabric or other material is incorporated into body gear), and
each heat-
reflecting element may have a heat-reflecting surface and may be positioned to
reflect heat
towards a heat source, such as a user's body. Additionally, a plurality of
spacer elements may
be coupled to the first side of the base material. In various embodiments,
each spacer element
may maintain a space, such as an air space, between the first side of the base
material, and
may prevent or reduce contact between the heat-reflecting elements and an
underlying
surface, such as a base layer, intermediate layer of clothing, and/or a user's
skin, thereby
reducing heat conduction through the base material.
In various embodiments, each spacer element may project away from the first
side of
the base material at least 0.05 ¨ 5.0 mm, such as about 0.05 ¨ 2.0 mm. In
various
embodiments, the spacers may take any of a number of forms, and may in some
examples be
made from woven or non-woven pods, knitted material, foam elements, or
vertically oriented
fibers (VOF). In some embodiments, a spacer element made from vertically
oriented fibers
(e.g.. a VOF element) may include a plurality of fibers that are oriented
substantially
perpendicular to the surface of the base material. In various embodiments, at
least some of
the plurality of spacer elements may at least partially overlay and/or overlap
at least some of
the plurality of heat-reflecting elements. In some embodiments, the spacer
elements may
completely overlap or partially overlap the heat-reflecting elements. In
specific, non-limiting
examples, the spacer elements may cover, overlay, or overlap about 2 ¨ 40% of
the surface
area of the heat-reflecting elements, such as about 5 ¨ 25%. In various
embodiments, each
spacer element may have a maximum dimension of about 1 ¨ 6 mm, such as about 2
-3 mm,
and a center-to-center spacing of the spacer elements may be about 3 ¨ 5 mm.
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In various embodiments, the spacing and placement of both the heat-reflecting
elements and the spacer elements may leave portions of the base material
uncovered between
adjacent elements, and these uncovered portions of the base material may
provide moisture
vapor transmission, resulting in a breathable material, such as a breathable
fabric. In some
embodiments, at least 15% of the base material may remain uncovered by both
heat-
reflecting elements and spacer elements, such as about 20%, about 30%, about
35%, or about
50%. In various embodiments, the heat-reflecting elements may cover a
sufficient surface
area of the base material to reflect a desired amount of heat, such as body
heat, towards the
body of a user, such as at least 30% of the base material
In various embodiments, the spacer elements may provide enhanced insulation
compared to base material alone. In various embodiments, the spacer elements
may prevent
or reduce contact between the heat-reflecting elements and an underlying
surface, such as the
surface of a base layer, or intermediate fabric or material layer, which may
in turn reduce heat
conduction by the heat-reflecting elements. Additionally, in various
embodiments, the spacer
elements may prevent or reduce contact between the heat-reflecting elements
and the skin of
a user, which may in turn reduce heat conduction by the heat-reflecting
elements. In various
embodiments, the spacer elements also may maintain space between the base
material and an
underlying surface, such as the surface of a base layer, or intermediate
fabric or material
layer, which may facilitate air flow and/or ventilation and enhance the
sensation of
breathability. In various embodiments, the spacer elements also may maintain
space between
the skin of a user and the base material, which may facilitate air flow and/or
ventilation and
enhance the sensation of breathability. Furthermore, the overlapping placement
of the spacer
elements and the heat-reflecting elements surprisingly does not reduce the
amount of heat
reflected by the heat-reflecting elements, or reduce the heat reflected as
much as expected. In
some embodiments, any loss of heat reflection may be more than offset by a
corresponding
decrease in heat conduction. In embodiments, a disclosed insulating material
exhibits at least
a 50% increase in insulation value over the base material from which it was
constructed, for
example at least 75%, at least 100%, at least 125%, at least 150%, at least
175%, at least
200%, at least 225% or even at least 250% greater insulation value over the
value of the base
material from which it was constructed, such as between about 50% and about
230% greater
insulation value than the base material from which it was constructed, for
example a material
that does not include either heat-reflecting elements or spacer elements as
described herein.
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One of the most significant advantages of the disclosed materials is that the
base
material, such as base fabric, containing heat-reflecting elements and spacer
elements, such
as vertically oriented fiber elements, provides greater insulation than the
base material alone
by a surprising and unexpected amount. By adding the spacer elements and the
heat-
reflecting elements to the base material, heat is trapped and/or retained by
the insulating
material in a synergistic manner. As demonstrated in the Example below, and as
specifically
shown in Table 2, the inclusion of both spacer elements and the heat-
reflecting elements to a
base fabric has almost a two-fold increase over what would be expected from a
simple linear
addition of the effect of the spacer elements and the heat-reflecting elements
alone. This
synergistic effect provides for an insulating material that far exceeds
expectations.
FIGs. 1,2, and 3 illustrate atop view (FIG. 1), aside view (FIG. 2), and a
perspective
view (FIG. 3) of one example of an insulating material, in accordance with
various
embodiments. With reference to FIGs. 1, 2, and 3, the insulating fabric 100
may include a
base material 102, such as a base fabric having an MVTR of at least 2000
g/m2/24h, which
may allow moisture vapor to move away from the user's body and through the
base material
so as to prevent moisture build up inside the body gear. Additionally, the
base material 102
may have one or more additional functional characteristics that are
appropriate for its
intended use. The base material 102 may be made from any material or materials
that
provides the desired set of functional characteristics, feel, weight,
thickness, weave, texture,
and/or other desired property, and may include nylon, polyester, rayon,
cotton, spandex,
wool, silk, or a blend thereof In specific, non-limiting embodiments, the base
material may
be a "performance" material, such as a performance synthetic knit or woven
material that has
a high MVTR (for example, at least 2000 g/m2/24h, JIS1099 Al) and an air
permeability of
above 10-30 CFM on a Frazier device. In some embodiments, the first side of
the base
material may be flat for easier application of the heat-reflecting elements
and/or spacer
elements.
With continued reference to FIGs. 1, 2, and 3, the insulating material 100
also may
include a plurality of heat-reflecting elements 104 coupled to a first side of
the base material
102. As used herein, the term "first side" refers to the side of the base
material 102 that is
intended to face the user's body when the base material 102 is incorporated
into body gear,
whether that side contacts the user's body (such as when the insulating
material 100 is used
as the innermost or only layer in an article of body gear), or not (such as
when the insulating
material 100 is incorporated into the article of body gear as an intermediate
or outermost
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layer). In various embodiments, each heat-reflecting element 104 may have a
heat-reflecting
surface and may be positioned to reflect heat towards the user's body.
As used herein, the term -heat-reflecting element" refers to a unitary element
having a
surface that reflects electromagnetic radiation having longer wavelengths than
those of
visible light (e.g., the infrared range, which extends from the nominal red
edge of the visible
spectrum at 700 nanometers (frequency 430 THz), to 1 mm (300 GHz) for the
purpose of this
disclosure). This range includes most of the thermal radiation emitted by
objects near room
temperature. In various embodiments, the heat-reflecting elements also may
reflect
electromagnetic radiation in other parts of the spectrum, such as the visible
spectrum. In
various embodiments, the heat-reflecting elements are formed from a metallic
plastic or a
foil, such as a film vacuum-metallized with aluminum. Various embodiments may
include a
film vacuum-metallized with aluminum which is coated with a thin lacquer. In
various
embodiments, the thin lacquer overcoat may contain pigments or dyes to modify
the
reflection of electromagnetic radiation in the visible range, thereby
modifying the color of the
reflective foil, while at the same time not significantly reducing the
reflectance of
electromagnetic radiation in the thermal IR range (5 to 35 microns). For
example, the
pigmented foil may be less than 1% lower thermal IR reflectance than the non-
pigmented
foil, less than 2% lower thermal IR reflectance than the non-pigmented foil,
or less than 5%
thermal IR reflectance than the non-pigmented foil. Generally, the heat-
reflecting elements
may include aluminum, silver, or any other heat-reflecting metal, or more
generally, a low-
emissivity heat reflective material. In particular embodiments, the heat
reflecting elements
may have an emissivity of no higher than 0.1, such as no higher than 0.08, no
higher than
0.06, or no higher than 0.04.
In various embodiments, the heat-reflecting elements may cover 30-70% of the
base
material (e.g., the surface area ratio of heat-reflecting elements to base
material may be from
7:3 to 3:7), such as 40-60% (e.g., a surface area coverage ratio of from 4:6
to 6:4). In various
embodiments, the heat-reflecting elements may be coupled to the base material
with an
adhesive. In various embodiments, the heat-reflecting elements and/or spacer
elements may
be coupled to the base material with a glue or an adhesive, such as a urethane
or acrylate-
based adhesive. In some embodiments, the glue or adhesive may be adsorbent or
absorbent,
for example to aid in moving moisture outward from the body.
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In various embodiments, the heat-reflecting elements may be applied in a
pattern or a
continuous or discontinuous array, such as a repeating or non-repeating
pattern of separate,
discrete elements (e.g., dots, rings, lines, stripes, waves, triangles,
squares, hexagons, stars,
ovals, or other geometric patterns or shapes, or logos, words, etc.) or a
repeating or non-
repeating pattern of interconnected elements (such as a lattice). In various
embodiments, a
pattern of heat-reflecting elements may be symmetric, ordered, random, and/or
asymmetrical.
Further, the pattern, size, shape, or spacing of the heat-reflecting elements
may differ at
strategic locations in the body gear as dictated by the intended use of the
article of body gear.
In various embodiments, the size of the heat-reflecting elements may be
largest (or the
spacing between them may be the smallest) in the core regions of the body for
enhanced heat
reflection in those areas, and the size of the heat-reflecting elements may be
the smallest (or
the spacing between them may be the largest) in peripheral areas of the body.
In other
embodiments, the size of the heat-reflecting elements may be smallest (or the
spacing
between them may be the largest) in the core regions of the body, and the size
of the heat-
reflecting elements may be the largest (or the spacing between them may be the
smallest) in
peripheral areas of the body for enhanced heat reflection in those areas. In
some
embodiments, the degree of coverage by the heat-reflecting elements may vary
in a gradual
fashion over the entire garment as needed for regional heat management. In
some
embodiments, reducing the area of individual elements, but increasing the
density may
provide a better balance between heat reflection and base material
functionality. In some
embodiments, the surface area of individual heat-reflecting elements may be
less than 1 cm'.
In various embodiments, each heat-reflecting element may have a maximum
dimension
(diameter, hypotenuse, length, width, etc.) that is less than or equal to
about 1 cm, such as 4
mm, or 1 mm.
With continued reference to FIGs.1, 2, and 3, in certain specific, non-
limiting
examples, the insulating material also may include a plurality of vertically
oriented fiber
(VOF) elements 106 coupled to the first side of the base material 102, and
each VOF element
106 may include a plurality of fibers that are oriented substantially
perpendicular to the
surface of the base material. As used herein, the term "VOF element" refers to
a unitary
element having a plurality of substantially perpendicular fibers. In various
embodiments, the
VOF elements may be discrete pods that contain a high density of vertically
oriented fibers,
such as at least 200 VOF fibers for a high denier, fairly coarse fiber. In
various embodiments,
the fibers may comprise nylon, polypropylene, or polyester. In various
embodiments, the
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fibers may include nylon, rayon, polyester, and/or cotton fibers. The fibers
may be wicking
fibers in some embodiments. As defined herein, the term -wicking" refers to a
fiber that
allows transport of a fluid along its length, which for a VOF fiber means
generally
perpendicular to the plane of the base material. In various embodiments, the
VOF elements
and/or the individual fibers may be coupled to the base material with an
adhesive. In other
embodiments, the VOF fibers may be integrated into the material by
embroidering, weaving,
or knitting.
In various embodiments, the vertically oriented fibers may have an average
length of
0.2 - 2.0 mm, such as about 0.6 mm, and an average linear density of 0.9 - 22
dtex, such as
1.7 dtex. In various embodiments, the fibers may be selected and arranged to
maximize
capillary forces between the fibers.
The VOF elements may be applied in a pattern or a continuous or discontinuous
array,
such as a repeating or non-repeating pattern of separate, discrete elements
(e.g., dots, rings,
lines, stripes, waves, triangles, squares, hexagons, stars, ovals, or other
geometric patterns or
shapes, or logos, words, etc.) or a repeating or non-repeating pattern of
interconnected
elements (such as a lattice). In various embodiments, a pattern of VOF
elements may be
symmetric, ordered, random, and/or asymmetrical. Further, the pattern, size,
shape, or
spacing of the VOF elements may differ at strategic locations in the article,
such as body
gear, as dictated by the intended use of the article.
In various embodiments, at least a portion of the base material remains
uncovered
between adjacent heat-reflecting elements, and between adjacent VOF elements.
Additionally, at least a portion of the base material may remain uncovered
between both
types of elements, such as at least 10-25%.
In various embodiments, the VOF elements may prevent or reduce contact between
the heat reflecting elements and the underlying surface, such as a base layer
or body surface.
In various embodiments, the insulating material (including the base material,
heat-reflecting
elements, and VOF elements) may have a MVTR of at least 2000 g/m2/24h (ES 1099
Al).
The insulating material may form all or a part of any article, such as used as
body or outdoor
gear, for example a coat, jacket, shirt, shoe, boot, slipper, base layer,
glove, mitten, hat, scarf,
pants, sock, tent, backpack or sleeping bag. In certain embodiments the heat-
reflecting
elements and the spacer element are positioned on the innermost surface of an
article, for
example on the innermost surface of a base layer, such as the innermost
surface of a base
layer facing toward the skin of a subject.
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FIG. 4 illustrates a perspective view of a second example of an insulating
material
400, including a base material 402, a plurality of heat-reflecting elements
404, and a plurality
of VOF elements 406, in accordance with various embodiments. As illustrated,
in some
embodiments at least a portion of the VOF elements 406 may overlap with and/or
overlay at
least a portion of the heat-reflecting elements 404.
FIG. 5 is a digital image of a third example of an insulating material 500,
including a
base material 502, a plurality- of heat-reflecting elements 504, and a
plurality of VOF
elements 506; and FIG. 6 is a digital image of a fourth example of an
insulating material 600,
including a base material 602, a plurality of heat-reflecting elements 604,
and a plurality of
VOF elements 606, in accordance with various embodiments. In some embodiments,
the
VOF elements 606 may include dyed or pigmented fibers.
FIGS. 7A, 7B, 7C, and 7D are heat escape maps measured with an IR thermal
imaging camera, for base material with VOF elements (FIG. 7A), base material
alone (FIG.
7B), base material with heat-reflecting elements (FIG. 7C), and base material
with heat-
reflecting elements and VOF elements (FIG. 7D), in accordance with various
embodiments.
These images were measured on circular material samples (approx. 6.9-cm-
diameter) placed
face down on an insulated hot plate assembly using a FUR SC83000 HD Series
high speed
MWIR megapixel infrared camera. The insulated hot plate assembly consisted of
a 0.125"
thick 6061 aluminum alloy plate as the test surface, which was placed on top
of a silicone
resistive heating pad (McMaster -Carr p/n 35765K708), which was on top of 2"
thick cork
insulation. The test surface plate had slots cut into it in a rectangular
shape to produce a
uniform temperature on the test surface. The test surface was also painted
matte black to
approximate the emissivity of skin (in = 0.95 2
¨black paint (P arsons) ¨ 0.98). A variable transformer
was adjusted to provide a steady-state surface temperature. (See, e.g.,
Incropera, F., DeWitt,
D., Bergman, T., and Lavine, A., Fundamentals of Heat and Mass Transfer, 6111
Edition, John
Wiley & Sons, 2007.)
Also disclosed in various embodiments are methods of making an insulating
material,
which methods generally include coupling a plurality of heat-reflecting
elements to a first
side of a base material having a moisture vapor transfer rate (MVTR) of at
least 2000
g/m2/24h (JIS 1099 Al), each of the heat-reflecting elements having a heat-
reflecting surface;
and coupling a plurality of vertically oriented fiber (VOF) elements to the
first side of the
base material such that at least some of the plurality of VOF elements at
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overlay at least some of the plurality of heat-reflecting elements. Each VOF
element includes
a plurality of fibers oriented substantially perpendicular to a surface of the
base material.
In various embodiments, the heat-reflecting elements are coupled to the base
material
before the VOF elements are coupled to the base material. The heat-reflecting
elements may
be permanently coupled to the base material in a variety of ways, including,
but not limited to
laminating, gluing, heat pressing, printing, or welding, such as by hot air,
radiofrequency or
ultrasonic welding.
In various embodiments, the plurality of VOF elements may then be coupled to
the
first side of the base material by screen or gravure printing an adhesive
followed by
electrostatic deposition of short fibers. Other methods to add VOF elements
include
embroidering, weaving and knitting. For instance, in some embodiments, an
adhesive, such
as a single part or two-part catalyzed adhesive may be used to couple the VOF
elements to
the base material. The adhesive may be applied to the base material in a
desired pattern using
a printing process, and the fibers may then be deposited electrostatically on
the base material.
Un-adhered fibers may then be removed from the base material by vacuum.
In one specific, non-limiting example, the fibers may be dispensed from a
hopper
through a positive electrode grid, which may orient the fibers and accelerate
them towards the
base material surface. A grounded electrode may be positioned under the
material surface,
and the fibers may be vertically embedded in the adhesive in the areas in
which it was applied
to the base material, creating a plurality of VOF elements.
In another specific, non-limiting example, the adhesive may instead be applied
to a
transfer membrane, and the fibers may be electrostatically embedded in the
adhesive on the
transfer membrane, creating a plurality of VOF elements. The transfer membrane
may then
be used to apply the VOF elements to the base material.
As previously noted, in some embodiments the spacer material may be formed of
a
foam or a foam-like material (collectively referred to herein as a "foam-based
spacer
material"). Fig. 8 illustrates a top view of an alternative insulating
material 800 that includes
a foam-based spacer material, in accordance with various embodiments.
Specifically, the insulating material 800 may include a base material 802 and
one or
more heat-reflecting elements 804, which may be respectively similar to base
material 102
and heat-reflecting element 104. The insulating material 800 may also include
a foam-based
spacer material 806 as shown in Fig. 8. It will be noted that the foam-based
spacer material
806 is depicted as at least partially transparent for the sake of showing the
overlap between
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the spacer material 806 and the heat-reflecting elements 804, however, in
other embodiments
the foam-based spacer material would be opaque.
In some embodiments, the foam-based spacer material 806 may be or may include
a
material such as a polyacrylate, polyurethane, polyolefin, and/or blends or
copolymers of
such materials. In some embodiments, these base polymers may be compounded
with a
crosslinking agent and a blowing agent to create the foaming formulation. Such
a
crosslinking agent may be or include a peroxide-based crosslinking agent. The
foaming
formulation may contain a colorant, for example a dye or pigment. The foaming
formulation
may additionally contain a viscosity modifier as needed. The foaming
formulation may be
applied directly to a fabric surface via rotary or flat screen printing,
gravure printing, coating,
or some other technique. However, it will be understood that such material(s)
are intended
only as example materials, and in other embodiments the foam-based spacer
material 806
may be or may include one or more additional or alternative materials.
Additionally, in some
embodiments, the foam-based spacer material 806 may have a thickness of
approximately 0.1
millimeters (mm), but in other embodiments the thickness may be more or less.
For example,
in some embodiments the thickness may be between approximately 0.05 mm and
approximately 0.15 mm (or higher). As used in this example, the term
"thickness" refers to
the maximum distance that the foam-based spacer material 806 extends when
measured from
the underlying surface of the base material 802.
As may be seen, in some embodiments the foam-based spacer material 806 may at
least partially overlap one or more of the heat-reflecting element(s) 804. In
some
embodiments, the foam-based spacer material 806 may be configured in a
generally linear
fashion, as shown in Fig. 8. In other embodiments, the foam-based spacer
material 806 may
be configured in a cross-hatch pattern, a circular pattern, a hexagonal
pattern, a random or
pseudo-random pattern, or some other pattern. It will be understood that the
specific depicted
dimensions of both the heat-reflecting elements 804 and the foam-based spacer
material 806
are intended as one example of such dimensions, and in other embodiments the
heat-
reflecting elements 804 and/or the foam-based spacer material 806 may have a
different
shape, configuration, or dimensions than shown in Fig. 8.
In some embodiments, the insulating material 800 may not include the heat-
reflecting
elements 804. Rather, the foam-based spacer material 806 may be used directly
with the base
material 802. Such an embodiment may be desired if the foam-based spacer
material 806
alone provides sufficiently improved thermal performance without the need to
apply the heat-
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reflecting element, thereby eliminating the materials, processing and cost of
adding the heat-
reflecting elements. Such an embodiment may be possible by employing a foam
formulation
that leads to a closed-cell foam spacer material that also converts the
underlying base fabric
from an essentially two-dimensional material to a three-dimensional material
via "rippling".
The resulting structure may lead to improved thermal performance by (a)
trapping of air in
the spaces between the substrate and an underlying material (the spacer
effect, which is also
active when the heat-reflecting elements are present; (b) elimination of free
and forced
convection of the air trapped within the cells of the closed-cell foam
structure; and (c)
trapping of additional air due to the "rippled" three-dimensional topography
of the composite
material.
Fig. 9 illustrates an example digital image 900 of a foam-based spacer
material, in
accordance with various embodiments. Specifically, Fig. 9 depicts a view 900
of such a
foam-based spacer material (similar to foam-based spacer material 806) that
has a closed-cell
structure as described above. The existence of individual cells 905 may be
seen at various
areas of the view 900.
As previously described, the inclusion of a spacer may provide the benefit of
providing additional insulation between base material 802 and/or heat-
reflecting elements
(e.g., heat-reflecting elements 804) and the skin, or underlying clothing
layer, of a user of a
wearable garment that includes the insulating material 800. If the spacer is a
closed-cell-
foam-based spacer material 806, then the foam inherently includes air pockets
that, when
heated, will remain in place (e.g., hot air rises) and thereby provide
enhanced heat retention
compared to open-cell foams or more generally, open-cell structures such as
fabrics and
traditional insulation materials such as down or those based on synthetic
fibers and their
combinations.
In some embodiments, the application of the foam-based spacer material to the
base
material may cause a change in the base material. For example, in some
embodiments the
foam-based spacer material may be attached to the base material (and/or one or
more
intervening heat-reflecting elements) through the use of an adhesive material
such as a glue-
type material, an epoxy-type material, etc. In other embodiments, the foam-
based spacer
material may be deposited onto the base material (and/or one or more
intervening heat-
reflecting elements) and then cured. Such a curing process may be performed
using one or
more of a chemical curing agent, heat, radiation (e.g., ultraviolet or
infrared-based curing),
light in the visible spectrum, and/or some additional or alternative curing
technique. In this
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embodiment, the foam-based spacer material may at least partially shrink or
contract, which
may result in a change to the stnicture of the underlying base material.
As previously noted, in some embodiments a foam-based spacer material such as
the
foam-based spacer material 806 may be configured in a cross-hatch pattern, a
circular pattern,
a hexagonal pattern, a random or pseudo-random pattern, or some other pattern.
Fig. 10
illustrates a simplified top view of alternative configurations of a foam-
based spacer material,
in accordance with various embodiments. It will be noted that Fig. 10 is
intended as a
simplified high-level figure with the purpose of depicting possible
configurations of the
foam-based spacer material.
In one embodiment, an insulating material 1000a may include a base material
1002a
and foam-based spacer material 1006a. In another embodiment, an insulating
material 1000b
may include a base material 1002b and a foam-based spacer material 1006b. In
another
embodiment, an insulating material 1000c may include a base material 1002c and
a foam-
based spacer material 1006c. Generally, the base materials 1002a, 1002b, and
1002c may be
similar to base material 802. Similarly, foam-based spacer materials 1006a,
1006b, and 1006c
may be similar to foam-based spacer material 806.
As may be seen in Fig. 10, in one embodiment the foam-based spacer material
1006a
may have a circular pattern. In another embodiment, the foam-based spacer
material 1006b
may have a cross-hatch pattern. In another embodiment, the foam-based spacer
material
1006c may have a non-uniform random or pseudo-random pattern. It will be
understood that
these patterns are intended as examples of possible patterns for the sake of
discussion, and
other patterns may additionally or alternatively be used, with or without heat-
reflecting
elements.
In some embodiments, the foam-based spacer material may have a generally
hexagonal shape. Fig. 11 illustrates a simplified top view of an alternative
configuration of a
foam-based spacer material, in accordance with various embodiments.
Specifically, Fig. 11
depicts an insulating material 1100 that includes a base material 1102 and
foam-based spacer
material 1106, which may be respectively similar to insulating material 800,
base material
802, and foam-based spacer material 806.
As may be seen in Fig. 11, the foam-based spacer material 1106 may have a
general
hexagonal form. Additionally, in some embodiments the different foam-based
spacer
materials 1106 may be spaced apart from one another as shown in Fig. 11. In
this
embodiment, respective ones of the foam-based spacer materials 1106 may have a
width w of
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approximately 8 mm. Additionally, respective ones of the foam-based spacer
materials 1106
may have a height h of approximately 6 mm. The foam-based spacer materials
1106 may be
spaced apart from one another by a distance dl that is approximately 2.5 mm,
and a distance
d2 that is approximately 3 mm.
It will be understood that this embodiment is intended as an example
configuration,
and in other embodiments the width w, height h, and distances dl and/or d2 may
be different.
Additionally, the configuration of the foam-based spacer materials 1106 with
respect to one
another (e.g., the -staggered- type pattern where spacer materials of
different rows are offset
from one another) may be different in other embodiments. Additionally, the
orientation of the
respective foam-based spacer materials 1106 may be different in other
embodiments such that
each of the foam-based spacer materials 1106 may not be oriented in the same
direction as
one another. Other variations may be present in other embodiments.
Fig. 12 illustrates an example digital image of a foam-based spacer material,
in
accordance with various embodiments. Specifically, Fig. 12 illustrates an
example insulating
material 1200 that includes a base material 1202 and a foam-based spacer
material 1206,
which may be respectively similar to base material 1102 and foam-based spacer
material
1106.
Fig. 13 illustrates an example side view of an alternative insulating material
1300 that
includes a foam-based spacer material, in accordance with various embodiments.
In this
embodiment, the insulating material 1300 may include a base material 1302, one
or more
heat-reflecting elements 1304, and a foam-based spacer material 1306, which
may be
respectively similar to elements 802, 804, and 806. It will be understood that
the embodiment
of Fig. 13 is intended as a simplified depiction for the purposes of
discussion, and includes
several areas of uniformity (e.g., the generally straight configuration of the
foam-based
spacer material 1306 or the uniform rippling of the based material 1302) that
may not be
present in real-world implementations of embodiments of the present
disclosure.
Additionally, although the heat-reflecting elements 1304 are depicted in
certain locations of
the rippled base material 1302, in other embodiments at least one of the heat-
reflecting
elements 1304 may be located at a different portion of the base material 1302
with respect to
the "ripple- of the base material 1302.
Generally, Fig. 13 depicts a "rippling" of the base material 1302, which may
result
from the curing process of the foam-based spacer material 1306. This rippling
may be
because, for example, the foam-based spacer material 1306 may shrink during
the curing
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process, causing the base material 1302 to "bunch up" or ripple. In some
embodiments, the
rippling may be beneficial because it may introduce extra distance (and
therefore increased
insulation) between the skin of a user of a garment that includes the
insulating material 1300
and at least portions of the base material 1302. Specifically, as may be seen,
the base material
1302 itself may have a thickness ti. However, due to the rippling effect of
the base material
1302, the base material 1302 may have a functional thickness t2 that is
greater than ti. In
some embodiments, ti may be on the order of approximately 0.68 mm. Similarly,
in some
embodiments t2 may be on the order of approximately 0.84 mm. This additional
functional
thickness t2 > ti may contribute to the above-described increased insulation.
Fig. 14 illustrates a side view of an alternative insulating material 1400
that includes a
foam-based spacer material, in accordance with various embodiments. In this
embodiment,
the insulating material 1400 may include a base material 1402 and a foam-based
spacer
material 1406, which may be respectively similar to elements 1302 and 1306. It
will be
additionally noted that, in this example embodiment, the heat-reflecting
elements (e.g.,
elements similar to heat-reflecting elements 1304) may not be present. For
example, in this
embodiment the rippled base material 1402 and the foam-based spacer material
1406 may
provide a desirable amount of heat-retention such that additional heat-
reflecting elements are
un-necessary as described above. It will be understood that, similarly to Fig.
13, the
embodiment of Fig. 14 is intended as a highly simplified depiction for the
purposes of
discussion, and includes several areas of uniformity or placement of certain
elements that
may not be present in real-world implementations of embodiments of the present
disclosure.
Similarly to Fig. 13, Fig. 14 depicts a "rippling" of the base material 1402,
which may
result from the curing process of the foam-based spacer material 1406. This
rippling may
generate one or more cavities, as may be seen.
The alteration to the configuration of the base material 1402 may provide a
benefit in
that an additional insulating portion of air may be present between the base
material 1402 and
contact with a user of the insulating material 1400. Such an additional
portion of air may
provide additional heat-retention from the insulating material 1400.
Generally, it will be understood that the embodiments of Figs. 13 and 14 may
be
views taken along a cross-section of a configuration of the insulating
material such as that
shown in Fig. 8 (with or without the heat-reflecting elements 804 as seen in
Figs. 13 and 14,
respectively). Specifically, the embodiment of Fig. 13 may be considered to be
a cross-
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sectional view taken along line B-B' of Fig. 8. The embodiment of Fig. 14 may
be considered
to be a cross-sectional view taken along line C-C' of Fig. 8.
Fig. 15 illustrates an example side view of an alternative insulating material
1500 that
includes a foam-based spacer material 1506, in accordance with various
embodiments.
Specifically, the insulating material 1500 includes base material 1502 and
foam-based spacer
materials 1506, which may be respectively similar to base material 1102 and
foam-based
spacer materials 1106. Specifically, in this embodiment, the foam-based spacer
materials
1506 may be discrete elements as shown, rather than a continuous element such
as is depicted
in Figs. 13 and 14. Such discrete elements may correspond to the foam-based
spacer
materials depicted in Figs. 10 and/or 11. In other embodiments, Fig. 15 may be
considered to
represent the embodiment of Fig. 8 (which may or may not include heat-
reflecting elements
804) as viewed along a cross-sectional line A-A' of Fig. 8. In other words,
the foam-based
spacer materials 1506 may be the discrete foam-based spacer materials 806.
Additionally, similarly to Fig. 14, it will be noted that in this embodiment a
heat-
reflecting element may not be desirable, as the foam-based spacer materials
1506 and the
rippled base material 1502 may provide a desirable amount of heat-retention
without the need
for such additional heat-reflecting elements.
As described above with respect to Figs. 13 and 14, in some embodiments the
foam-
based spacer material may be deposited on the base material in some manner,
and then it may
contract during the curing process. Such contraction may cause the rippling of
the base
material. As may be seen in Fig. 15, the "peaks" of the ripple of the base
material 1502 may
be at the locations where the foam-based spacer material 1506 is present.
Additionally, as a
result of such rippling and "peaks," subsequent cavities 1508 may be
introduced into the base
material 1502.
Fig. 16 illustrates example digital images 1601a and 1601b of an insulating
material
1600 that includes a foam-based spacer material, in accordance with various
embodiments.
Specifically, the digital images 1601a and 1601b may be considered to be
digital images of
the simplified embodiment of Fig. 15 using the configuration of the foam-based
spacer
materials depicted in Fig. 11. Fig. 16 depicts an insulating material 1600
with a base material
1602 that includes cavities 1608 and foam-based spacer materials 1606, which
may be
respectively similar to base material 1502, cavities 1508, and foam-based
spacer materials
1506. Image 1601a may be a perspective-view image taken from the backside (FS
in Fig. 15)
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of the insulating material 1500. Similarly, image 1601b may be a perspective-
view image
taken from the frontside (BS in Fig. 15) of the insulating material 1500.
The -ripple" of the base material 1602 may be seen in Fig. 16. Specifically,
the image
1601a depicts the various cavities 1608 that correspond to the locations of
the foam-based
spacer materials 1606, as described above with respect to Fig. 15.
It will be understood that the embodiments depicted and discussed herein with
respect
to, for example, Figs. 8, 10, 11, 13, 14, and 15 are intended as example
embodiments for the
sake of discussion. Unless indicated otherwise, the various elements of those
Figures are not
drawn to scale, but rather certain features may be exaggerated for the
purposes of discussion
or visibility.
EXAMPLES
In various embodiments, the insulating materials described herein may have
superior
insulating characteristics as compared to other insulating materials,
including materials that
include heat-reflecting materials without VOF elements. As shown in Table 1
below, four
different base materials were tested using standard hot plate testing. Samples
of the four
different base materials were tested in three different configurations: no
heat reflecting or
VOF elements ("Fabric"), heat-reflecting elements only ("Fabric + heat-
reflecting element-),
and with both heat-reflecting and VOF elements (-Fabric + heat-reflecting
element +
vertically oriented fiber"). Heat flux (W) and dry heat transfer rate (w/ m2
L.) were
measured, and an average insulation value (do = 0.155 K_sna2=W-1) was
calculated for each.
As used herein, the term -heat" refers to thermal energy transported due to a
temperature
gradient (J or Ca/). As used herein, the term "heat rate" refers to thermal
energy transported
per unit time (ks = W). As used herein, the term "heat flux- refers to heat
rate per unit area.
As used herein, the term -thermal transmittance" refers to heat flux per unit
temperature
gradient (W/m2 K). As used herein, the term "thermal resistance" refers to the
reciprocal of
thermal transmittance (m2K/W) and do, which is 0.155 m2-K/W, is a unit of
measure for
insulation value. The results of testing of specific examples of limited
conduction heat
reflective materials is shown below in Table 1.
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Table 1: Thermal Resistance Data Measured Using Standard Hotplate Testing
Fabric Fabric + heat- Fabric + heat-reflecting
reflecting element +
vertically
element oriented
fiber
Base fabric 053165
Total thermal resistance,
0.423 0.003 0.403 0.003 0.467 0.003
Ret (do)'
Thermal resistance of the
0.068 0.004 0.048 0.003 0.112 0.009
fabric alone, Rcf (clo)
Base fabric 033770
Total thermal resistance,
0.478 0.010 0.425 0.015 0.484 0.008
Ret (do)'
Thermal resistance of the
0.123 0.011 0.070 0.015 0.129 0.008
fabric alone, Rcf (do)
Base fabric 031908
Total thermal resistance,
0.387 0.013 0.376 0.007 0.455 0.011
1?cr (do)'
Thermal resistance of the
0.032 0.013 0.021 0.007 0.100 0.011
fabric alone, Rcf (clo)
Base fabric 060360
Total thermal resistance,
0.560 + 0.033 0.559 + 0.007 0.668 + 0.015
Rt (do)2
Thermal resistance of the
0.047 0.046 0.155
fabric alone, R cf (C1 o)
'Bare plate thermal resistance, &bp (do) = 0.353 0.002
2Bare plate thermal resistance, KN., (do) = 0.514 (no standard deviation
provided)
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Dry heat transport data were measured in general accordance with ASTM F1868,
Part
A- Thermal Resistance. Tests were conducted on 4 different base fabrics, the
same fabrics
with heat-reflecting elements, and the same materials with heat-reflecting
elements plus
vertically oriented fiber. The results are shown in Table 1 as the total
thermal resistance, Rct,
and the thermal resistance of the fabric alone, RI. These values are given in
do units, and are
also known as insulation values. In all cases, the insulation values are lower
for the fabric +
heat-reflecting element as compared to the same base fabric. When spacer
elements (in this
case, vertically oriented fiber elements) are added, however, the insulation
values were
greater than they are for the base fabric and for the fabric + heat-reflecting
element by a
substantial amount. Depending on the specific base material, insulation values
of the
disclosed insulating materials typically exhibit from 50% to 230% greater
insulation values
than the base materials from which they were constructed.
Table 2. Area-averaged Temperature from Heat Escape Maps
Average Backside
Temperature Difference
Material Surface Temperature
from Base Material ( C)
( C)
Fabric (-Base") 33.4
Fabric -h vertically oriented fiber
32.5 0.9
("VOF only")
Fabric + heat-reflecting elements
32.3 1.1
("OHR only")
Fabric heat-reflecting element +
29.7 3.7
vertically oriented fiber ("OH3D")
Figures 7A, 7B, 7C, and 7B show heat escape maps measured with an IR thermal
imaging camera, for base fabric with VOF elements (FIG. 7A), base fabric alone
(FIG. 7B),
base fabric with heat-reflecting elements (FIG. 7C), and base fabric with heat-
reflecting
elements and VOF elements (FIG. 7D), in accordance with various embodiments.
The
circular samples were placed face down on an insulated hot plate assembly set
at
approximately 37 C. The thermal images were taken of the backside of each of
the fabric
samples. Thus, for the fabric samples that contain VOF, heat-reflecting
elements, or both,
these features face toward the hot plate and therefore cannot affect the
sample emissivity
toward the infrared camera. As a result, the measured signal is an accurate
measure of the
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temperature of the backside of each fabric, and representative of the amount
of heat that
escapes through the fabric.
Area-averaged temperatures from the heat escape maps of Figure 7 are shown in
Table 2. The highest average temperature, and the temperature closest to the
temperature of
the hot plate, is 33.4 C for the base fabric. Thus, the most heat escapes
through the base
fabric, which is the least insulating of the four fabrics measured. The next
highest average
temperature is 32.5 C for the base fabric + vertically oriented fiber ("VOF
only"), followed
by 32.3 C for the base fabric + heat-reflecting elements ("OUR only"). The
lowest average
temperature is 29.7 C for the base fabric + heat-reflecting elements +
vertically oriented
fiber ("OH3D"). Thus, the least amount of heat escapes through this fabric,
which is the most
insulating of the four fabrics measured.
Most significantly, the base fabric containing heat-reflecting elements +
vertically
oriented fiber is more insulating than the base fabric by a surprising and
unexpected amount.
By adding vertically oriented fiber to the base fabric, sufficient heat is
trapped to lower the
backside average temperature by 0.9 C (see Table 2). By adding heat-
reflecting elements to
the base fabric, sufficient heat is trapped to lower the backside average
temperature by 1.1
C. By adding both elements to the base fabric, one might expect the combined
effect would
lead to a lower temperature of around 2 C (0.9 C + 1.1 "V), or even less
since the elements
overlap. However, the combined effect is nearly twice this amount. The
combined effect of
VOF and heat-reflecting elements traps enough heat to lower the backside
average
temperature by 3.7 C.
In another embodiment, foam pods (which may be similar to foam-based spacer
materials such as those depicted at elements 1606 or 1106) were added to a
base knit fabric
(which may be similar to a base material such as base material 1602 or 1102),
and the thermal
resistance was measured for comparison against the same base fabric. As shown
in Table 3,
the effective thickness of a base knit fabric was increased from 0.68 mm to
0.84 mm, which
is a 24% increase in thickness due to the presence of the foam pods and the
"rippling" effect
described above. However, surprisingly, the thermal resistance increased by
greater than a
factor of 2, or more than 100%. Fundamentally, it is expected that the
insulation value of
fabrics is linearly related to their thickness; thus, it is expected that
increasing the insulation
value by 100% would require a doubling of the thickness from 0.68 mm to 1.36
mm for this
base fabric. By applying and curing foam pods to this fabric, the insulation
value was
doubled with only an increase in the effective thickness by 24%.
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Material Thickness (mm) Thermal resistance,
Rd. (do)
Base knit fabric 0.68 0.087
0.010
Base knit fabric + hexagonal 0.84 0.178
0.007
foam pods
Thermal imaging was conducted of the base fabric containing hexagonal foam
pods.
The material was placed on a hot plate at 35 degrees Celsius ( C). During the
cooling cycle,
thermal images were collected as shown at 1700 in Fig. 17, showing the foam
pods at a
higher temperature than the fabric to which they are affixed. Specifically,
Fig. 17 depicts a
thermal image of a fabric (e.g., a base material 1702 such as base material
1602) with a
plurality of hexagonal foam-based spacer materials 1706 (e.g., such as foam-
based spacer
materials 1606) during a cooling cycle after being heated on a hotplate to 35
C. The closed-
cell nature of the foam pods renders them more insulative than an open-cell
foam would be,
and more insulative than the underlying base fabric, which is essentially an
open-cell
structure as well.
Although certain embodiments have been illustrated and described herein, it
will be
appreciated by those of ordinary skill in the art that a wide variety of
alternate and/or
equivalent embodiments or implementations calculated to achieve the same
purposes may be
substituted for the embodiments shown and described without departing from the
scope.
Those with skill in the art will readily appreciate that embodiments may be
implemented in a
very wide variety of ways. This application is intended to cover any
adaptations or variations
of the embodiments discussed herein. Therefore, it is manifestly intended that
embodiments
be limited only by the claims and the equivalents thereof.
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