Technical Field
[0001] Embodiments of the present disclosure relate generally to fabrics used for apparel
having enhanced cooling properties, and in particular to fabrics that utilize absorbent
polymer elements coupled to a wicking base fabric to enhance cooling.
Background
[0002] Performance fabric materials such as wicking materials and cooling materials typically
take the form of uniform layers that are woven into or otherwise incorporated into
the interior of a garment. Cooling fabrics that incorporate a layer of cooling materials
such as highly absorbent polymers have shortcomings, particularly when incorporated
into the fabric as a continuous layer. For example, a uniform layer of polymer material
may impede the transfer of moisture vapor or restrict air passage through the fabric.
Furthermore, such cooling materials may impede a desired characteristic of the base
fabric, such as drape, texture and stretch. Thus, the use of a layer of cooling material
may impede the breathability (or another function) of the underlying base fabric.
[0003] EP 1894 482 A2 relates to textile fabrics which are responsive to change in moisture or temperature,
which includes a smooth surface with one or more regions having a bound coating of
hydrogel exhibiting expansion or contraction in response to change in relative humidity
or exposure to liquid sweat. According to an aspect of the fabric described in this
prior art document, a temperature and moisture responsive textile fabric garment includes
a thermal fabric having a smooth outer surface, and a plurality of discrete regions
of hydrogel disposed in a pattern corresponding to one or more predetermined regions
of a user's body and bound to the smooth outer surface of the thermal fabric. The
hydrogel exhibits expansion or contraction in response to change in relative humidity
or exposure to liquid sweat, adjusting insulation performance, air movement or liquid
management of the textile fabric.
[0004] US 2003/0208831 A1 discloses a cooling garment constructed, at least in part, of a cooling fabric. The
cooling fabric includes an upper layer that includes a water-resistant fabric, a lower
layer that includes a water-resistant fabric, a plurality of chambers disposed between
the upper layer and the lower layer. The upper layer and the lower layer are connected
by stitching using a water wickable thread, and a superabsorbent polymer is contained
within a majority of the chambers.
[0005] WO 2013/044108 A1 discloses a fabric or other material used for apparel and other goods having designed
performance characteristics. It discloses also methods and apparatuses that utilize
a pattern of performance elements coupled to a base fabric to manage one or more performance
characteristics while maintaining the desired properties of the base fabric.
[0006] A first array of performance elements directs or absorbs or emits heat, wicks moisture,
or a combination thereof and a second array of second performance elements coupled
to the base material in a second zone performs a second function comprising directing
or absorbing heat or wicking moisture, or a combination thereof. In one particular
embodiment, the first array comprises a heat directing polymer and the second array
comprises a cooling polymer.
Brief Description of the Drawings
[0007] Embodiments of the present disclosure will be readily understood by the following
detailed description in conjunction with the accompanying drawings. Embodiments are
illustrated by way of examples.
Figures 1A-1D show several perspective views of one example of a cooling material having a base
fabric with a high moisture wicking rate and a discontinuous pattern of highly absorbent
polymer elements disposed thereon, including a view of moisture contacting one portion
of the base fabric (Figure 1A), a view of the base fabric dispersing the moisture over a large surface area via
a wicking action (Figure 1B), a view of the highly absorbent polymer elements absorbing moisture from the base
fabric (Figure 1C), and a view of the moisture evaporating from the absorbent polymer elements (Figure 1D), in accordance with various embodiments;
Figures 2A-2H illustrate a variety of specific examples of patterns of individual highly absorbent
polymer elements in accordance with various embodiments;
Figures 3A-3F illustrate a variety of specific examples of patterns of interconnected highly absorbent
polymer elements, in accordance with various embodiments; and
Figures 4A and Figure 4B show a comparison of the efficacy of a control cooling polymer fabric (Figure 4A) versus a new cooling material (Figure 4B) having a base fabric with a high moisture wicking rate, and a highly absorbent polymer
element disposed thereon, in accordance with various embodiments.
Detailed Description of Embodiments
[0008] 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
in which the disclosure 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 of the claims.
[0009] Various operations may be described as multiple discrete operations in turn, in a
manner that may be helpful in understanding embodiments of the present disclosure.
[0010] 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.
[0011] 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.
[0012] For the purposes of the description, a phrase in the form "A/B" or in the form "A
and/or B" means (A), (B), 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.
[0013] The description may use the phrases "in an embodiment," or "in embodiments," which
may each refer to one or more of the same or different embodiments. Furthermore, the
terms "comprising," "including," "having," as used with respect to embodiments of
the present disclosure, are synonymous.
[0014] In various embodiments, cooling materials for clothing and other body gear are disclosed
that may use a discontinuous pattern (whether interconnected or having independent
elements) of highly absorbent polymer elements coupled to a body-facing surface of
a base fabric that has a low resistance to moisture spread (e.g., a high wicking rate).
In various embodiments, the highly absorbent polymers may leave portions of the base
fabric exposed, for example, areas of the base fabric may be left uncovered between
or among the highly absorbent polymer elements. Additionally, the highly absorbent
polymer elements may be significantly more absorbent than the base fabric, such as
two. three, four, five, or even ten or more times more absorbent. In various embodiments,
the cooling materials may be used to manage moisture (e.g.. sweat) and body heat.
[0015] In various embodiments, when the cooling material is exposed to moisture, the base
fabric may quickly wick the moisture away from the skin. The moisture may then be
dispersed through/along the base fabric over a wide surface area via a wicking action,
and the highly absorbent polymer elements may begin absorbing moisture, both from
the base fabric and directly from the skin. In various embodiments, this process may
cause a redistribution of moisture, first from a localized area of the base fabric
to a larger area of the base fabric, and then from the base fabric into the highly
absorbent polymer elements.
[0016] Thus, in various embodiments, by spreading the moisture over a large surface area
of the base fabric, and by drawing the moisture from the base fabric into the highly
absorbent polymer elements, evaporation from the base fabric may be facilitated, which
may accelerate the evaporative cooling experienced by the wearer. Additionally, in
various embodiments, once the highly absorbent polymer elements have absorbed moisture
from the base fabric, they may retain the moisture close to the skin surface and produce
a prolonged evaporative cooling sensation for the user, for example when compared
to that produced by the base fabric alone. In various embodiments, the highly absorbent
polymer elements, and the uncovered portions of base fabric therebetween, may permit
the base fabric to retain certain desired characteristics, such as stretch, drape,
breathability, moisture vapor transfer, air permeability, and/or wicking.
[0017] For the purposes of the present description, the term "discontinuous pattern of highly
absorbent polymer elements" includes an ordered or disordered pattern of independent
elements, a matrix of interconnected elements, or a hybrid of both, with portions
of the base fabric left exposed and uncovered by the elements between or amongst the
discontinuous pattern. As used herein, the term "absorbance" refers to the ability
of a fiber or a polymer to absorb moisture, for example by diffusion. Absorbance typically
is expressed as a percentage of weight of the starting material. By contrast, as used
herein, the term "wicking" or "wickability" refers to the movement of bulk fluid along
or between fibers, for example in a fabric or other textile. As such, a fabric or
other textile may have both a high wicking rate and low absorbance.
[0018] As used herein, the term "endothermic" as applied to a process refers to a process
in which the system absorbs energy from its surroundings in the form of heat. As applied
to a fabric or composition, the term "endothermic" as used herein refers to a fabric
or composition that absorbs heat from its surroundings, for instance upon a change
of state or upon absorbing water or other fluids. For an endothermic reaction, Δ
H (the change in enthalpy) is greater than zero.
[0019] Figures 1A-1D show several perspective views of one example of a cooling material having a base
fabric with a high moisture wicking rate and a discontinuous pattern of highly absorbent
polymer elements disposed thereon, including a view of moisture contacting one portion
of the body-facing side of the base fabric (
Figure 1A), a view of the base fabric dispersing the moisture over a large surface area via
a wicking action (
Figure 1B), a view of the highly absorbent polymer elements absorbing moisture from the base
fabric (
Figure 1C), and a view of the moisture evaporating from the absorbent polymer elements through
the base fabric and away from the body (
Figure 1D), in accordance with various embodiments. In various embodiments, a cooling material
100 may include a plurality of highly absorbent polymer elements
104 disposed on a base fabric.
[0020] Thus, in various embodiments, the base fabric
102 may have a high moisture wicking rate and a low absorbance compared to the absorbance
of the highly absorbent polymer elements
104. Wicking rate may be measured using any of a variety of tests known to those of skill
in the art. For instance, one measure involves determining the distance a fixed volume
of moisture spreads from an emanation point when dropped onto the surface of a fabric.
Generally, the greater the distance the moisture travels from the emanation point,
the stronger the 'wickability" of the fabric. Other suitable tests of wicking rate
include the Vertical Wick Test (e.g.. AATCC 197) and the moisture management test
(MMT). As defined herein, a fabric having a "high wicking rate" wicks at least three
inches in ten minutes as measured using the Vertical Wick Test (AATCC 197).
[0021] Absorbance is also easily determined in a laboratory setting. In various embodiments,
for example, when measured with a moisture sorption balance at 30°C and 80% relative
humidity, the base fabric
102 may absorb about 0 - 2.0% of its weight in moisture, such as about 0.25 - 1.5%. about
0.5 - 1.0%. or about 0.8%. In various embodiments, by contrast, when measured with
a moisture sorption balance at 30°C and 80% relative humidity, the highly absorbent
polymer elements
104 may absorb about 3.0 - 20% of their weight in moisture, such as about 3.3%, about
5.0%. or about 10%. In some embodiments, the highly absorbent polymer elements
104 may absorb even more moisture, such as about 50% or even 100% of their weight in
water.
[0022] In various embodiments, the highly absorbent polymer elements
104 may be several fold more absorbent than the base fabric
102, such as about 2X, 3X 4X 5X, 10X, 20X, 50X, 100X, 200X, or even 300X (or more) as
absorbent than the base fabric
102. For example, in one specific example, the highly absorbent polymer elements
104 may absorb about 3.3% moisture by weight as measured under the conditions listed
above, whereas the base fabric
102 may absorb only about 0.8% moisture by weight, making for about a four-fold difference
in absorbance between the base fabric
102 and the highly absorbent polymer elements
104. Without being bound by theory, it is believed that this absorbance differential between
the base fabric
102 and the highly absorbent polymer elements
104 pulls moisture from the base fabric
102 into the highly absorbent polymer elements
104, thus enhancing evaporative cooling and creating a sensation of dryness in the base
fabric
102.
[0023] In various embodiments, the highly absorbent polymer elements
104 may be disposed in a generally discontinuous array or pattern, whereby some of the
base fabric
102 may be exposed within or between adjacent highly absorbent polymer elements
104. In various embodiments, the highly absorbent polymer elements
104 may be arranged in an array of separate elements, whereas in other embodiments, discussed
at greater length below, the highly absorbent polymer elements
104 may be arranged in an interconnected pattern. In some embodiments, a highly absorbent
polymer element may take the form of a solid shape or closed loop member, such as
a circle, square, hexagon, or other shape. In other embodiments, the discontinuous
pattern of highly absorbent polymer elements
104 may take the form of a lattice, grid, or other interconnected pattern.
[0024] As illustrated in
Figures 1A and
1B, the highly absorbent polymer elements
104 are positioned on the surface of the base fabric
102 facing the wearer's skin, and as moisture
106 contacts the base fabric
102 (
Figure 1A) (for instance, in the form of sweat from the skin of the wearer), it begins to spread
and disperse laterally through the base fabric
102 (
Figure 1B) due to the base fabric's high moisture wicking rate and low resistance to moisture
spread. In some embodiments, the base fabric
102 may be treated with a hydrophilic compound in order to increase its moisture wicking
rate or a hydrophobic compound to assist in movement of moisture in a desired direction.
The base fabric's lower absorbance (compared to that of the highly absorbent polymer
elements
104) also permits the moisture to travel freely within the cooling material
100.
[0025] As illustrated in
Figure 1C. moisture may then contact the highly absorbent polymer elements
104 and may begin to be absorbed, enhancing evaporative cooling through the base fabric
102 and creating a sensation of dryness for the user. For example, in some embodiments,
the highly absorbent polymer elements
104 pull moisture from the surrounding base fabric
102, causing accelerated evaporation and allowing the base fabric
102 to dry quickly, for example more quickly than base fabric
102 dries without highly absorbent polymer elements
104. During this process, the highly absorbent polymer elements
104 absorb moisture from the base fabric
102, and this redistribution of the moisture is facilitated both by the absorbance properties
of the highly absorbent polymer elements
104 and the base fabric's low resistance to moisture spread and lower absorbance when
compared to the highly absorbent polymer elements
104. This redistribution of the moisture from the base fabric
102 to the highly absorbent polymer elements
104 accelerates evaporative cooling from the base fabric
102 (and thereby the skin of the user), and also prepares the cooling material
100 for more prolonged cooling.
[0026] In various embodiments, moisture may have a higher equilibrium concentration in the
highly absorbent polymer elements
104 than it has in the base fabric
102. Without being bound by theory, it is believed that this difference in absorbance
levels may create a concentration gradient within the cooling material
100 as the highly absorbent polymer elements
104 absorb moisture from the base fabric
102. In various embodiments, the moisture concentration gradient drives moisture out of
the base fabric
102 and into the highly absorbent polymer elements
104. As the highly absorbent polymer elements
104 absorb moisture from the base fabric
102, the base fabric
102 is then capable of absorbing more moisture, such as perspiration from the body.
[0027] As illustrated in
Figure 1D, moisture retained in the highly absorbent polymer elements
104 causes prolonged evaporation, pulling moisture in a direction away from the skin
of the wearer (see arrows) until the cooling material
100 returns to a dry state, in accordance with various embodiments. During this phase
of cooling, the base fabric
102 may be largely dry, and most of the cooling function of the cooling material
100 may be provided by evaporation from the highly absorbent polymer elements
104 during the prolonged cooling phase. In various embodiments, positioning the highly
absorbent polymer elements
104 against (or next to) the skin of the wearer may help the wearer to experience a sensation
of prolonged evaporative cooling. For example, evaporation from the highly absorbent
polymer elements
104 causes a reduction in the temperature of the cooling elements
104 in much the same way that evaporation from the skin surface cools the skin. Thus,
in various embodiments, positioning the cooler highly absorbent polymer elements
104 on the body-facing surface of the base fabric
102 allows the wearer to perceive this cooling sensation, whereas the cooling sensation
may be less noticeable if the highly absorbent polymer elements
104 were positioned on the outward-facing surface of the base fabric
102. In some embodiments, the cooling fabrics disclosed herein may provide a cooling phase.
defined as the period of cooling resulting from evaporation of a particular quantity
of liquid/sweat, that lasts 110%, 120%, 150%, 200% (or even more) as long as the cooling
phase provided by the base fabric alone.
[0028] Prior to the present disclosure, it was widely believed that positioning the cooling
elements on the outward-facing surface of the base fabric
102 would produce a superior cooling effect, as this arrangement allows for evaporation
from the highly absorbent polymer elements
104 to proceed unencumbered by the base fabric
102. However, as disclosed herein, it has now been found that positioning the highly absorbent
polymer elements
104 on the body-facing surface of the base fabric
102 enhances the coolness sensation perceived by the wearer, while still allowing moisture
to evaporate and a steady rate through the base fabric
102.
[0029] As described below in greater detail, the highly absorbent polymer elements
104 may include one or more hygroscopic polymers, such as a polymer that may absorb and
retain a liquid, and in some examples, may absorb extremely large amounts of a liquid
relative to its mass. Hygroscopic polymers that absorb large amounts of liquids are
referred to as superabsorbent polymers.Such water absorbing polymers, which are classified
as hydrogels when cross-linked, absorb aqueous solutions through hydrogen bonding
with water molecules. A superabsorbent polymer's ability to absorb water generally
is a factor of the ionic concentration of the aqueous solution. For instance, in deionized
and distilled water, a superabsorbent polymer may absorb 500 times its weight (for
example, from 30-60 times its own volume) and can become up to 99.9% liquid, but when
put into a 0.9% saline solution, the absorbency drops to approximately 50 times its
weight.
[0030] In various embodiments, the total absorbance and swelling capacity may be controlled
by the type and degree of cross-linkers used to make the gel. Low density cross-linked
superabsorbent polymers generally have a higher absorbent capacity and swell to a
larger degree. These types of superabsorbent polymers also have a softer and more
sticky gel formation. High cross-link density polymers exhibit lower absorbent capacity
and swell, but the gel strength is firmer and can maintain particle shape even under
modest pressure.
[0031] Superabsorbent polymers are commonly made from the polymerization of acrylic acid
blended with sodium hydroxide in the presence of an initiator to form a poly-acrylic
acid sodium salt (e.g., sodium polyacrylate). Other materials also may be used to
make a superabsorbent polymer, such as polyacrylamide copolymer, ethlyene maleic anhydride
copolymer, cross-linked carboxymethylcellulose. polyvinyl alcohol copolymers, cross-linked
polyethylene oxide, and starch grafted copolymer of polyacrylonitrile (PAN). In other
embodiments, the polymers may be a homopolymer, and may include polysaccharides, polyurethanes.
polyamides. polyacrylates.
[0032] In specific embodiments, a highly absorbent polymer element may include, for example,
any suitable natural or synthetic polymeric material that, in a dry form, is capable
of absorbing and storing many times its weight in water. Specific examples of natural
gums that may be used in highly absorbent polymer elements include xanthan, agar,
pectin, locust bean gum, hydroxypropyl guar gum, polyglucomannan gum, cationic guar
gum, anionic guar gum, alginate, irish moss, and gum arabic. Specific examples of
cellulosics that may be used in highly absorbent polymer elements include methyl cellulose,
ethyl cellulose, carboxymethyl cellulose, carboxy ethyl cellulose, hydroxyethyl cellulose,
hydroxymethyl cellulose, and hydroxypropylcellulose.
[0033] Specific examples of synthetic hydrogel polymers that may be used in highly absorbent
polymer elements include suitable crosslinked, water-swellable acrylic copolymers.
In particular embodiments, the synthetic hydrogel polymers may include copolymers
that include repeat units from one or more monomers selected from (meth)acrylic acid,
maleic acid. 2-(meth)acrylamido-2-methyl propane sulfonic acid, styrene sulfonate,
vinyl sulfonic acid. and their corresponding ammonia, amine and alkali metal salts,
(meth)acrylamide, vinyl alcohol. vinyl acetate, maleic anhydride, alkyl vinyl ethers,
vinylmorpholinone, vinylpyrridine, vinyl pyrrolidone, and acrylonitrile; and one or
more crosslinking agents selected from N,N-methylenebis(meth)acrylamide, (poly)ethylene
glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, trimethylolpropane
tri(meth)acrylate, glycerol tri(meth)acrylate, glycerol acrylate methacrylate, ethylene-oxide-modified
trimethylolpropane tri(meth)acrylate. pentaerythritol tetra(meth)acrylate, dipentaerythritol
hexa(meth)acrylate, triallyl cyanurate, triallyl isocyanurate, triallyl phosphate,
triallylamine, poly(meth)allyloxyalkanes, (poly)ethylene glycol diglycidyl ether.
glycerol diglycidyl ether, ethylene glycol, polyethylene glycol, propylene glycol.
glycerol, pentaerythritol, ethylenediamine, ethylene carbonate, propylene carbonate,
polyethylenimine, glycidyl (meth)acrylate, diallyl sucrose, triallyl sucrose triallyl
amine, and triallyl methyl ammonium chloride. Other specific examples of cooling polymers
may include paraffin (C
nH
2n2+), fatty acids (CH
3(CH
2)
2nCOOH), salt hydrates (M
nH
2O), hygroscopic materials, trimethylolethane, and lauric acid. In particular embodiments,
the highly absorbent polymer elements may include polyacrylate and/or sodium polyacrylate
mixed or cross-linked with a non-soluble compound, such as polyurethane.
[0034] Other specific examples include styrenic block copolymers, which are thermoplastic
elastomers that may include at least three blocks, for instance two hard polystyrene
end blocks and one soft, elastomeric (e.g., polybutadiene, polyisoprene, or their
hydrogenated equivalents) midblock. In various embodiments, the hard and soft blocks
may be immiscible, so that, on a microscopic scale, the polystyrene blocks form separate
domains in the rubber matrix, thereby providing physical cross links to the rubber.
[0035] Additional highly absorbent polymers and methods to manufacture such polymers are
described in
U.S. Patent Nos. 6,469,080,
6,399,668.
6,127,454,
6.087.002,
5,244,735,
4,925,603, and
4,734.478. Additional examples of highly absorbent polymers that may be used in accordance
with various embodiments include those available under the trade names ALCOSORB® from
Ciba Specialty Chemicals. Chatanooga, Tenn.; DRYTECH® from the Dow Chemical Company,
Midland, Mich.; NORSOCRYL® and AQUAKEEP® from Atofina, Paris. France: HYDROSORB™ from
HYDROSORB Inc., Orange, Calif.; AQUALIC CA® from Nippon, Shokubai Co., Ltd., Osaka.
Japan; and PERMAX™ from The Lubrizol Corporation, Wickliffe, Ohio.
[0036] In various embodiments, the highly absorbent polymer elements
104 may cover a sufficient surface area of the base fabric
102 to achieve the desired degree of cooling, for example, having a surface coverage
area of the highly absorbent polymer elements
104 of about 5 - 50%, about 10 - 40%, about 15 - 30%, or about 20% in various embodiments.
This coverage range leaves about 50 - 95%, about 60 - 90%, about 70 - 85%, or about
80% of the base fabric
102 uncovered in various embodiments. Generally, a sufficient area of base fabric
102 should be exposed to provide the desired base fabric function (e.g., stretch, drape,
texture. breathability, moisture vapor transfer, air permeability, and/or wicking).
For example, if there is too little exposed base fabric, properties such as moisture
vapor transfer and/or permeability may suffer greatly, and even disproportionately
to the percentage of coverage. As used herein, the term "surface coverage area" refers
to a measurement taken from seam to seam on a given garment, and does not necessarily
correspond to the percentage of the entire garment covered by the highly absorbent
polymer elements.
[0037] In accordance with various embodiments, the base fabric 102 may be a part of any
form of clothing or bodywear, which term is used herein to include anything worn on
or used close to the body, including athletic wear such as compression garments, t-shirts.
shorts, tights, sleeves, headbands outerwear such as jackets, pants, scarves. shirts,
hats, gloves, mittens. footwear such as shoes, boots. slippers, sleepwear, such as
pajamas, nightgowns, and robes, undergarments such as underwear, thermal underwear,
undershirts, brassieres, socks, hosiery and other items used close to the body, such
as bedding. towels and backpacks.
[0038] In various embodiments, the highly absorbent polymer elements 104 may be disposed
on a base fabric
102 having one or more desired properties or characteristics. For example, the underlying
base fabric
102 may have properties such as air permeability, moisture vapor transfer, and/or wickability,
which are common needs for bodywear used in both indoor and outdoor applications.
In some embodiments, the underlying base fabric
102 may have other desirable attributes. such as abrasion resistance, anti-static properties,
anti-microbial activity, water repellence, flame repellence, hydrophilicity, hydrophobicity,
wind resistance, UV protection, resiliency, stain resistance, wrinkle resistance.
In some embodiments, the areas of uncovered base fabric
102 between and/or inside highly absorbent polymer elements
104 may help allow the base fabric
102 to have a desired drape, look, stretch, and/or texture. Specific examples of suitable
base fabrics
102 may include nylon, polyester, rayon, cotton, spandex, wool, silk. or a blend thereof,
or any other material having a desired look, feel. weight, thickness, weave, texture,
or other desired property. One example for a suitable base fabric
102 is a fabric made from polyester fiber, although any fabric having suitable properties,
such as high wickability and very low absorbance may be used. As used herein, the
term "low absorbance" when used with reference to a fabric, refers to a fabric having
fibers that absorb less than 1.0% moisture by weight when measured at 80% relative
humidity and 30°C.
[0039] In various embodiments, configuring the cooling material to allow a designated percentage
of the base fabric
102 to remain uncovered by the highly absorbent polymer elements
104 may allow that portion of the base fabric
102 to perform the desired functions, while still leaving enough surface area of highly
absorbent polymer elements
104 to cool the body to a desired degree. In various embodiments, single-layer bodywear
may be used, and may be comprised of a single layer of the base fabric
102, whereas other embodiments may use multiple layers of fabric, including, for example,
one or more additional layers of the base fabric or another fabric. For instance,
the base fabric
102 may be used as a fabric lining for bodywear.
[0040] In various embodiments, the highly absorbent polymer elements
104 may be disposed on a lower or inside surface of the base fabric
102 (e.g., an inside surface of the body gear, facing the skin), placing the highly absorbent
polymer elements
104 in a good position for absorbing sweat directly from the skin of a user. However,
in some embodiments, the highly absorbent polymer elements
104 may be at least partially integrated into or may at least partially permeate base
fabric
102. so long as they still face the body of a user.
[0041] In various embodiments, the highly absorbent polymer elements
104 may have little or no endothermicity. Endothermicity is measured using Differential
scanning calorimetry (DSC). which is a technique that monitors heat effects associated
with phase transitions and chemical reactions as a function of temperature. In a DSC,
the difference in heat flow to the sample and a reference at the same temperature
is recorded as a function of temperature. The reference is an inert material such
as alumina, or just an empty aluminum pan. The temperature of both the sample and
reference are increased at a constant rate. Since the DSC is at constant pressure,
heat flow is equivalent to enthalpy changes, and can be either positive or negative.
In an endothermic process, such as most phase transitions, heat is absorbed and, therefore,
heat flow to the sample is higher than that to the reference. Hence ΔdH/dt is positive.
[0042] In various embodiments, the absorbance of water by certain materials, including certain
superabsorbent polymers, is an endothermic process. Prior to the present disclosure,
it was believed that the endothermic properties of certain materials, such as cooling
polymers and phase change materials, caused the bulk of the cooling sensation perceived
by a user of a cooling fabric incorporating these materials. Thus, prior to the present
disclosure, polymers deemed suitable for use in cooling fabrics typically had at least
some endothermic properties.
[0043] Surprisingly, as disclosed herein, it has now been found that endothermic properties
are not necessary or desirable properties for a cooling polymer, as evaporative cooling
provides the bulk of the cooling effect that is perceived by a user when the highly
absorbent elements are positioned on the body-facing surface of the base fabric. Additionally,
endothermic materials can be costly and may have other undesirable characteristics
relating to durability and texture. As such, in various embodiments, a highly absorbent
polymer for use in the disclosed cooling fabrics may have no endothermic properties.
As defined herein, a "non-endothermic" polymer is defined herein to include any polymer
having an enthalpy of less than 10 Jg
-1 as measured by DSC.
[0044] In various embodiments, the highly absorbent polymer elements
104 may be permanently coupled to the base fabric
102 in a variety of ways by gluing, heat pressing, printing, or stitching. In some embodiments,
the cooling elements may be coupled to the base fabric by frequency welding, such
as by radio or ultrasonic welding. In some embodiments, the highly absorbent polymer
elements
104 may be coupled to the base fabric using gravure coating. In some specific examples,
the gravure coating process may use an engraved roller running in a coating bath,
which fills the engraved dots or lines of the roller with the coating material (e.g..
the gel making up the cooling elements). The excess coating on the roller may be wiped
off using a blade, and the coating may then be deposited onto the substrate (e.g.,
the base fabric) as it passes between the engraved roller and a pressure roller. In
various embodiments, the gravure coating process may include direct gravure. reverse
gravure, or differential offset gravure. and in various embodiments, the coat weight
may be controlled by the percent of solids, the gravure volume, the pattern depth,
and/or the speed of the gravure cylinder.
[0045] In various embodiments, the highly absorbent polymer elements may be applied in a
pattern or a continuous or discontinuous array. For example, as illustrated in
Figures 2A -2H. the highly absorbent polymer elements may take the form of an array of discrete solid
or closed loop members, adhered or otherwise secured to the base fabric in a desired
pattern. Such a configuration has been found to provide cooling to the user while
still allowing the base fabric to perform desired properties (e.g., breathe and stretch).
In various embodiments, such discontinuous, discrete, separate cooling elements may
take the form of circles, triangles, squares, pentagons, hexagons, octagons, stars,
crosses, crescents, ovals, or any other solid shape or a substantially closed loop
member that includes a center portion inside the closed loop member wherein the base
fabric remains exposed.
[0046] Although the embodiments illustrated in
Figures 2A - 2H show the highly absorbent polymer elements as separate, discrete elements, in some
alternate embodiments, some or all of cooling elements may be arranged such that they
are in connection with one another, such as stripes or a matrix/lattice pattern or
any other pattern that permits partial coverage of the base fabric. For example, as
illustrated in
Figures 3A - 3F, the configuration of cooling elements disposed on a base fabric may be in the form
of a variety of partially or completely, and the pattern may combine both discontinuous
elements (such as those illustrated in
Figures 2A -
2H) and interconnected geometrical patterns (such as those illustrated in
Figures 3A -
3F). In various embodiments, the pattern of highly absorbent polymer elements may be symmetrical,
ordered, random, and/or asymmetrical. Further, as discussed below, the pattern of
highly absorbent polymer elements may be disposed on the base fabric at strategic
locations to improve the performance of the bodywear. In various embodiments, the
size and/or spacing of the highly absorbent polymer elements may also be varied in
different areas of the bodywear to balance the need for enhanced cooling properties
and preserve the functionality of the base fabric.
[0047] In various embodiments, the placement, pattern, and/or coverage ratio of the cooling
elements may vary. For example the cooling elements may be concentrated in certain
areas where cooling may be more critical (e.g., the body core) and non existent or
extremely limited in other areas where the function of the base fabric property is
more critical. In various embodiments, different areas of the bodywear may have different
coverage ratios, e.g. 30% at the chest and 5% at the limbs, in order to help optimize,
for example, the need for cooling and breathability.
[0048] In various embodiments, the size of the highly absorbent polymer elements may be
largest (or the spacing between them may be the smallest) in the core regions of the
body for enhanced cooling in those areas. and the size of the highly absorbent polymer
elements may be the smallest (or the spacing between them may be the largest) in peripheral
areas of the body. In some embodiments, the degree of coverage by the highly absorbent
polymer elements may vary in a gradual fashion over the entire garment as needed for
regional cooling.
Examples
Example 1
[0049] This example illustrates a comparison of the heat-managing properties of an existing
cooling polymer fabric (Omni Freeze Zero™) with a new cooling material that has a
discontinuous pattern of highly absorbent polymers coupled to a base fabric that has
a low resistance to moisture spread. The temperature of both fabrics was measured
after having moisture added using a steamer.
Figure 4A illustrates the Delta T of the control cooling polymer fabric, and
Figure 4B illustrates the Delta T of the new cooling material. The new cooling material performed
better, reaching a larger Delta T while keeping an extended cooling beyond the control
cooling polymer fabric.