U.S. patent application number 11/078656 was filed with the patent office on 2005-09-22 for polymeric composites having enhanced reversible thermal properties and methods of forming thereof.
Invention is credited to Hartmann, Mark H., Magill, Monte C..
Application Number | 20050208286 11/078656 |
Document ID | / |
Family ID | 36992184 |
Filed Date | 2005-09-22 |
United States Patent
Application |
20050208286 |
Kind Code |
A1 |
Hartmann, Mark H. ; et
al. |
September 22, 2005 |
Polymeric composites having enhanced reversible thermal properties
and methods of forming thereof
Abstract
Polymeric composites and methods of manufacturing polymeric
composites are described. In one embodiment, a set of microcapsules
containing a phase change material are mixed with a dispersing
polymeric material to form a first blend. The dispersing polymeric
material has a latent heat of at least 40 J/g and a transition
temperature in the range of 0.degree. C. to 50.degree. C. The first
blend is processed to form a polymeric composite. The polymeric
composite can be formed in a variety of shapes, such as pellets,
fibers, flakes, sheets, films, rods, and so forth. The polymeric
composite can be used as is or incorporated in various articles
where a thermal regulating property is desired.
Inventors: |
Hartmann, Mark H.;
(Superior, CO) ; Magill, Monte C.; (Greeley,
CO) |
Correspondence
Address: |
COOLEY GODWARD, LLP
3000 EL CAMINO REAL
5 PALO ALTO SQUARE
PALO ALTO
CA
94306
US
|
Family ID: |
36992184 |
Appl. No.: |
11/078656 |
Filed: |
March 11, 2005 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
11078656 |
Mar 11, 2005 |
|
|
|
10891428 |
Jul 13, 2004 |
|
|
|
10891428 |
Jul 13, 2004 |
|
|
|
09777512 |
Feb 6, 2001 |
|
|
|
6793856 |
|
|
|
|
60234150 |
Sep 21, 2000 |
|
|
|
Current U.S.
Class: |
428/292.1 |
Current CPC
Class: |
C08J 3/226 20130101;
Y02E 60/145 20130101; C08L 101/00 20130101; F28D 20/023 20130101;
Y02E 60/14 20130101; C08K 5/01 20130101; C08L 23/06 20130101; C08J
2423/00 20130101; D01F 1/10 20130101; C08J 3/201 20130101; C08L
2201/00 20130101; C08J 2323/02 20130101; D04H 1/42 20130101; D01D
1/065 20130101; Y10T 428/249924 20150401; C08L 101/00 20130101;
C08L 2666/02 20130101 |
Class at
Publication: |
428/292.1 |
International
Class: |
D04H 001/00 |
Claims
What is claimed is:
1. A method of manufacturing a polymeric composite, comprising:
mixing a plurality of microcapsules containing a phase change
material with a dispersing polymeric material to form a first
blend, the dispersing polymeric material having a latent heat of at
least 40 J/g and a transition temperature in the range of 0.degree.
C. to 50.degree. C.; and processing the first blend to form the
polymeric composite.
2. The method of claim 1, wherein the phase change material has a
latent heat of at least 40 J/g and a transition temperature in the
range of 0.degree. C. to 50.degree. C.
3. The method of claim 1, wherein the phase change material
includes a paraffinic hydrocarbon having from 16 to 22 carbon
atoms.
4. The method of claim 1, wherein the plurality of microcapsules
are coated with water to form a wet cake.
5. The method of claim 4, further comprising heating the first
blend until the first blend includes less than 1 percent by weight
of water.
6. The method of claim 1, wherein the latent heat of the dispersing
polymeric material is at least 60 J/g.
7. The method of claim 1, wherein the transition temperature of the
dispersing polymeric material is in the range of 22.degree. C. to
40.degree. C.
8. The method of claim 1, wherein the dispersing polymeric material
includes a polymer selected from the group consisting of
polyethylene, polyethylene glycol, polyethylene oxide,
polypropylene, polypropylene glycol, polytetramethylene glycol,
polypropylene malonate, polyneopentyl glycol sebacate, polypentane
glutarate, polyvinyl myristate, polyvinyl stearate, polyvinyl
laurate, polyhexadecyl methacrylate, polyoctadecyl methacrylate,
and polyesters.
9. The method of claim 1, wherein the mixing the plurality of
microcapsules with the dispersing polymeric material includes:
melting the dispersing polymeric material to form a melt; and
dispersing the plurality of microcapsules in the melt to form the
first blend.
10. The method of claim 9, wherein the dispersing polymeric
material has an affinity for the plurality of microcapsules to
facilitate dispersing the plurality of microcapsules in the
melt.
11. The method of claim 1, wherein the processing the first blend
to form the polymeric composite includes: processing the first
blend to form granules; mixing the granules with a matrix polymeric
material to form a second blend; and processing the second blend to
form the polymeric composite.
12. The method of claim 11, wherein the processing the first blend
to form the granules includes: cooling the first blend to form a
solid; and granulating the solid to form the granules.
13. The method of claim 11, wherein the matrix polymeric material
includes a high molecular weight polymer.
14. The method of claim 11, wherein the mixing the granules with
the matrix polymeric material includes: melting the matrix
polymeric material to form a melt; and dispersing the granules in
the melt to form the second blend.
15. The method of claim 14, wherein the matrix polymeric material
has an affinity for the dispersing polymeric material to facilitate
dispersing the granules in the melt.
16. The method of claim 11, wherein the mixing the granules with
the matrix polymeric material includes: dry blending the granules
with the matrix polymeric material to form a dry blend; heating the
dry blend to form the second blend.
17. The method of claim 11, wherein the polymeric composite is
formed as pellets, and the processing the second blend includes:
cooling the second blend to form a solid; and granulating the solid
to form the pellets.
18. A method of manufacturing a polymeric composite, comprising:
melting a first temperature regulating material to form a first
melt; dispersing a second temperature regulating material in the
first melt to form a first blend; processing the first blend to
form granules; melting a matrix polymeric material to form a second
melt; dispersing the granules in the second melt to form a second
blend; and processing the second blend to form the polymeric
composite.
19. The method of claim 18, wherein the first temperature
regulating material includes a polymeric phase change material
having a latent heat of at least 50 J/g and a transition
temperature in the range of 10.degree. C. to 50.degree. C.
20. The method of claim 18, wherein the second temperature
regulating material includes a plurality of microcapsules
containing a phase change material having a latent heat of at least
50 J/g and a transition temperature in the range of 10.degree. C.
to 50.degree. C.
21. The method of claim 20, wherein the first temperature
regulating material includes a polymer having an affinity for the
plurality of microcapsules.
22. The method of claim 18, wherein the processing the first blend
includes: extruding the first blend into a thread; and granulating
the thread to form the granules.
23. The method of claim 18, wherein the matrix polymeric material
includes a polymer having an affinity for the first temperature
regulating material.
24. The method of claim 18, wherein the matrix polymeric material
includes a polymer selected from the group consisting of
polyamides, polyamines, polyimides, polyacrylics, polycarbonates,
polydienes, polyepoxides, polyesters, polyethers,
polyflourocarbons, formaldehyde polymers, natural polymers,
polyolefins, polyphenylenes, silicon containing polymers,
polyurethanes, polyvinyls, polyacetals, polyarylates, and mixtures
thereof.
25. The method of claim 18, wherein the polymeric composite is
formed as pellets, and the processing the second blend includes:
extruding the second blend into a thread; and granulating the
thread to form the pellets.
26. A method of manufacturing a polymeric composite, comprising:
melting a first polymeric material to form a first melt, the first
polymeric material having a latent heat of at least 40 J/g and a
transition temperature in the range of 0.degree. C. to 50.degree.
C.; dispersing a temperature regulating material in the first melt
to form a first blend, the temperature regulating material
including a phase change material having a latent heat of at least
40 J/g and a transition temperature in the range of 0.degree. C. to
50.degree. C.; mixing the first blend with a second polymeric
material to form a second blend; and processing the second blend to
form the polymeric composite.
27. The method of claim 26, wherein the first polymeric material
corresponds to a dispersing polymeric material.
28. The method of claim 26, wherein the temperature regulating
material further includes a containment structure that contains the
phase change material.
29. The method of claim 26, wherein the first polymeric material
and the second polymeric material are different.
30. The method of claim 26, wherein the second polymeric material
corresponds to a matrix polymeric material.
31. The method of claim 26, wherein the mixing the first blend with
the second polymeric material includes: melting the second
polymeric material to form a second melt; and mixing the first
blend with the second melt to form the second blend.
32. The method of claim 26, wherein the polymeric composite is
formed as pellets, and the processing the second blend includes
extruding the second blend to form the pellets.
33. A polymeric composite, comprising: a polymeric material having
a latent heat of at least 40 J/g and a transition temperature in
the range of 0.degree. C. to 50.degree. C.; and a plurality of
microcapsules dispersed in the polymeric material, the plurality of
microcapsules containing a phase change material having a latent
heat of at least 40 J/g and a transition temperature in the range
of 0.degree. C. to 50.degree. C.
34. The polymeric composite of claim 33, wherein the latent heat of
the polymeric material is at least 60 J/g.
35. The polymeric composite of claim 33, wherein the transition
temperature of the polymeric material is in the range of 22.degree.
C. to 40.degree. C.
36. The polymeric composite of claim 33, wherein the polymeric
material includes a polymer selected from the group consisting of
polyethylene glycol, polyethylene oxide, polytetramethylene glycol,
and polyesters.
37. The polymeric composite of claim 33, wherein the phase change
material includes a paraffinic hydrocarbon having from 16 to 22
carbon atoms.
38. The polymeric composite of claim 33, wherein the polymeric
composite includes from 10 percent to 30 percent by weight of the
microcapsules containing the phase change material.
39. The polymeric composite of claim 33, wherein the polymeric
composite includes from 15 percent to 25 percent by weight of the
microcapsules containing the phase change material.
40. A polymeric composite, comprising: a blend of a polymeric
material and a non-encapsulated phase change material, the
polymeric material having a partial affinity for the
non-encapsulated phase change material, such that the
non-encapsulated phase change material forms a plurality of domains
dispersed in the polymeric material, the non-encapsulated phase
change material having a latent heat of at least 60 J/g and a
transition temperature in the range of 10.degree. C. to 50.degree.
C.
41. The polymeric composite of claim 40, wherein the polymeric
material includes a polymer selected from the group consisting of
polyolefins and copolymers of polyolefins.
42. The polymeric composite of claim 40, wherein the
non-encapsulated phase change material includes a paraffinic
hydrocarbon having from 16 to 22 carbon atoms.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of the patent
application of Hartmann et al., entitled "Melt Spinable Concentrate
Pellets Having Enhanced Reversible Thermal Properties," U.S.
application Ser. No. 10/891,428, filed on Jul. 13, 2004, which is a
continuation of the patent application of Hartmann et al., entitled
"Melt Spinable Concentrate Pellets Having Enhanced Reversible
Thermal Properties," U.S. application Ser. No. 09/777,512, filed on
Feb. 6, 2001, which claims the benefit of the patent application of
Hartmann et al., entitled "Melt Spinable Concentrate Pellets Having
Enhanced Reversible Thermal Properties," U.S. Provisional
Application Ser. No. 60/234,150, filed on Sep. 21, 2000, the
disclosures of which are incorporated herein by reference in their
entireties.
FIELD OF THE INVENTION
[0002] The invention relates to polymeric composites and their
manufacture. More particularly, the invention relates to polymeric
composites including phase change materials that are useful in the
manufacture of synthetic fibers.
BACKGROUND OF THE INVENTION
[0003] Many fabrics are made from synthetic fibers. Conventionally,
two processes are used to manufacture synthetic fibers: a wet
solution process and a melt spinning process. The wet solution
process is generally used to form acrylic fibers, while the melt
spinning process is generally used to form nylon fibers, polyester
fibers, polypropylene fibers, and other similar type fibers. As is
well known, an acrylic fiber includes a long-chain synthetic
polymer characterized by the presence of acrylonitrile units, a
nylon fiber includes a long-chain synthetic polyamide polymer
characterized by the presence of an amide group --CONH--, a
polyester fiber includes a long-chain synthetic polymer having at
least 85 percent by weight of an ester of a substituted aromatic
carboxylic acid unit, and a polypropylene fiber includes a
long-chain synthetic crystalline polymer having at least 85 percent
by weight of an olefin unit and typically having a molecular weight
of about 40,000 or more.
[0004] The melt spinning process is of particular interest, since a
large portion of the synthetic fibers that are used in the textile
industry are manufactured by this technique. The melt spinning
process generally involves passing a molten polymeric material
through a device that is known as a spinneret to thereby form a set
of individual synthetic fibers. Once formed, the synthetic fibers
can be collected into a strand or cut into staple fibers. Synthetic
fibers can be used to make woven or non-woven fabrics, or,
alternatively, synthetic fibers can be wound into a yarn to be used
thereafter in a weaving or a knitting process to form a synthetic
fabric.
[0005] Phase change materials have been incorporated into acrylic
fibers to enable the fibers to provide enhanced reversible thermal
properties and to enable fabrics made from such fibers to perform
similar functions. This is readily accomplished, in part due to the
high levels of volatile materials (e.g., solvents) typically
associated with the wet solution process of forming acrylic fibers.
However, it is more problematic to incorporate phase change
materials into melt spun synthetic fibers, since high levels of
volatile materials are typically not present or desired in the melt
spinning process. Previous attempts to incorporate phase change
materials into melt spun synthetic fibers typically involved mixing
the phase change materials with a standard fiber-grade
thermoplastic polymer to form a blend and subsequently melt
spinning this blend to form the synthetic fibers. Such attempts
generally led to inadequate dispersion of the phase change
materials within the fibers, poor fiber properties, and poor
processability unless low concentrations of the phase change
materials were used. However, with low concentrations of the phase
change materials, the desired enhanced reversible thermal
properties normally associated with use of the phase change
materials can be difficult to realize.
[0006] It is against this background that a need arose to develop
the polymeric composites described herein.
SUMMARY OF THE INVENTION
[0007] In one aspect, the invention relates to a method of
manufacturing a polymeric composite. In one embodiment, the method
includes: (a) mixing a set of microcapsules containing a phase
change material with a dispersing polymeric material to form a
first blend, the dispersing polymeric material having a latent heat
of at least 40 J/g and a transition temperature in the range of
0.degree. C. to 50.degree. C.; and (b) processing the first blend
to form the polymeric composite.
[0008] In another embodiment, the method includes: (a) melting a
first temperature regulating material to form a first melt; (b)
dispersing a second temperature regulating material in the first
melt to form a first blend; (c) processing the first blend to form
granules; (d) melting a matrix polymeric material to form a second
melt; (e) dispersing the granules in the second melt to form a
second blend; and (f) processing the second blend to form the
polymeric composite.
[0009] In a further embodiment, the method includes: (a) melting a
first polymeric material to form a first melt, the first polymeric
material having a latent heat of at least 40 J/g and a transition
temperature in the range of 0.degree. C. to 50.degree. C.; (b)
dispersing a temperature regulating material in the first melt to
form a first blend, the temperature regulating material including a
phase change material having a latent heat of at least 40 J/g and a
transition temperature in the range of 0.degree. C. to 50.degree.
C.; (c) mixing the first blend with a second polymeric material to
form a second blend; and (d) processing the second blend to form
the polymeric composite.
[0010] In another aspect, the invention relates to a polymeric
composite. In one embodiment, the polymeric composite includes: (a)
a polymeric material having a latent heat of at least 40 J/g and a
transition temperature in the range of 0.degree. C. to 50.degree.
C.; and (b) a set of microcapsules dispersed in the polymeric
material, the microcapsules containing a phase change material
having a latent heat of at least 40 J/g and a transition
temperature in the range of 0.degree. C. to 50.degree. C.
[0011] In another embodiment, the polymeric composite includes a
blend of a polymeric material and a non-encapsulated phase change
material. The polymeric material has a partial affinity for the
non-encapsulated phase change material, such that the
non-encapsulated phase change material forms a set of domains
dispersed in the polymeric material. The non-encapsulated phase
change material has a latent heat of at least 60 J/g and a
transition temperature in the range of 10.degree. C. to 50.degree.
C.
[0012] Other aspects and embodiments of the invention are also
contemplated. The foregoing summary and the following detailed
description are not meant to restrict the invention to any
particular embodiment but are merely meant to describe some
embodiments of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] For a better understanding of the nature and objects of the
invention, reference should be made to the following detailed
description taken in conjunction with the accompanying
drawings.
[0014] FIG. 1 illustrates a manufacturing process to form a
polymeric composite in accordance with an embodiment of the
invention.
[0015] FIG. 2 illustrates a manufacturing process to form a
polymeric composite in accordance with another embodiment of the
invention.
[0016] FIG. 3 illustrates a manufacturing process to form a
polymeric composite in accordance with a further embodiment of the
invention.
DETAILED DESCRIPTION
[0017] Embodiments of the invention relate to polymeric composites
having enhanced reversible thermal properties and methods of
manufacturing the same. Polymeric composites in accordance with
various embodiments of the invention have the ability to absorb and
release thermal energy under different environmental conditions. In
addition, the polymeric composites can exhibit, for example,
improved dispersion or higher loading levels of a phase change
material. The polymeric composites can be formed in a variety of
forms or shapes, such as pellets, fibers, flakes, sheets, films,
rods, and so forth. The polymeric composites can be used as is or
incorporated in various articles to provide a thermal regulating
property while providing improved strength to the articles. For
example, polymeric composites in accordance with various
embodiments of the invention can be used in textiles (e.g.,
fabrics), apparel (e.g., outdoor clothing, drysuits, and protective
suits), footwear (e.g., socks, boots, and insoles), medical
products (e.g., thermal blankets, therapeutic pads, incontinent
pads, and hot/cold packs), containers and packagings (e.g.,
beverage and food containers, food warmers, seat cushions, and
circuit board laminates), buildings (e.g., insulation in walls or
ceilings, wallpaper, curtain linings, pipe wraps, carpets, and
tiles), appliances (e.g., insulation in house appliances), and
other products (e.g., automotive lining material, sleeping bags,
and bedding).
[0018] Polymeric composites in accordance with various embodiments
of the invention can be processed to form a variety of articles
having enhanced reversible thermal properties. For example,
polymeric composites can be formed as pellets that are useful to
form synthetic fibers, for injection molding processes, or for
extrusion processes. Use of these pellets can provide benefits that
are achieved by incorporating a phase change material into a
variety of articles, which articles include, for example, fibers
such as acrylic fibers, nylon fibers, polyester fibers,
polyethylene fibers, and polypropylene fibers; films; foams; and
injection molded articles.
[0019] Polymeric composites in accordance with various embodiments
of the invention can provide an improved level of comfort when
incorporated in articles such as apparel or footwear. In
particular, the articles can provide such improved level of comfort
under different or changing environmental conditions. The use of
phase change materials allows the articles to provide
"multi-directional" or "dynamic" thermal regulation rather than
"unidirectional" or "static" thermal regulation. In particular, in
accordance with "multi-directional" thermal regulation, the
articles can absorb thermal energy in warm weather as well as
release thermal energy in cold weather. In such manner, the
articles can provide cooling in warm weather and heating in cold
weather, thus maintaining a desired level of comfort under
different weather conditions. And, in accordance with "dynamic"
thermal regulation, the articles can adapt or adjust their thermal
regulating property under changing environmental conditions. In
such manner, the articles can be capable of multiple uses, such as
for both warm weather and cold weather. Moreover, the articles can
adapt or adjust their thermal regulating property without requiring
an external triggering mechanism, such as moisture or sunlight.
[0020] In conjunction with a thermal regulating property provided,
polymeric composites in accordance with various embodiments of the
invention when incorporated, for example, in apparel or footwear
can provide other improvements in a level of comfort. For example,
articles incorporating the polymeric composites can provide a
reduction in an individual's skin moisture, such as due to
perspiration. In particular, the articles can lower the temperature
or the relative humidity of the skin, thereby providing a lower
degree of skin moisture and a higher level of comfort. The use of
specific materials and specific apparel or footwear design features
can further enhance the level of comfort. For example, the articles
can be used in conjunction with certain additives, treatments, or
coatings to provide further benefits in thermal regulating and
moisture management properties.
[0021] A polymeric composite according to some embodiments of the
invention can include one or more materials. According to some
embodiments of the invention, the polymeric composite can include a
temperature regulating material, a dispersing polymeric material,
and a matrix polymeric material. According to some embodiments of
the invention, the polymeric composite is a liquid melt mixture or
a solidified melt mixture of the temperature regulating material,
the dispersing polymeric material, and the matrix polymeric
material. Typically, the temperature regulating material is
uniformly dispersed within the polymeric composite. However,
depending upon the particular characteristics desired from the
polymeric composite, the dispersion of the temperature regulating
material can be varied within the polymeric composite. The
dispersing polymeric material and the matrix polymeric material can
be the same or different. It is also contemplated that one or more
of the temperature regulating material, the dispersing polymeric
material, and the matrix polymeric material can be omitted for
certain embodiments of the invention. For example, the polymeric
composite can include the temperature regulating material and the
dispersing polymeric material without requiring the matrix
polymeric material.
[0022] Depending on the method of manufacturing a polymeric
composite, desirability of further processing, or the particular
application of the polymeric composite, the polymeric composite can
further include one or more additives, such as water, surfactants,
dispersants, anti-foam agents (e.g., silicone containing compounds
and flourine containing compounds), antioxidants (e.g., hindered
phenols and phosphites), thermal stabilizers (e.g., phosphites,
organophosphorous compounds, metal salts of organic carboxylic
acids, and phenolic compounds), light or UV stabilizers (e.g.,
hydroxy benzoates, hindered hydroxy benzoates, and hindered
amines), light or UV absorbing additives (e.g., ceramic particles
of Group IV transition metal carbides and oxides), microwave
absorbing additives (e.g., multifunctional primary alcohols,
glycerine, and carbon), reinforcing-fibers (e.g., carbon fibers,
aramid fibers, and glass fibers), conductive fibers or particles
(e.g., graphite or activated carbon fibers or particles),
lubricants, process aids (e.g., metal salts of fatty acids, fatty
acid esters, fatty acid ethers, fatty acid amides, sulfonamides,
polysiloxanes, organophosphorous compounds, and phenolic
polyethers), fire retardants (e.g., halogenated compounds,
phosphorous compounds, organophosphates, organobromides, alumina
trihydrate, melamine derivatives, magnesium hydroxide, antimony
compounds, antimony oxide, and boron compounds), anti-blocking
additives (e.g., silica, talc, zeolites, metal carbonates, and
organic polymers), anti-fogging additives (e.g., non-ionic
surfactants, glycerol esters, polyglycerol esters, sorbitan esters
and their ethoxylates, nonyl phenyl ethoxylates, and alcohol
ethyoxylates), anti-static additives (e.g., non-ionics such as
fatty acid esters, ethoxylated alkylamines, diethanolamides, and
ethoxylated alcohol; anionics such as alkylsulfonates and
alkylphosphates; cationics such as metal salts of chlorides,
methosulfates or nitrates, and quaternary ammonium compounds; and
amphoterics such as alkylbetaines), anti-microbials (e.g., arsenic
compounds, sulfur, copper compounds, isothiazolins phthalamides,
carbamates, silver base inorganic agents, silver zinc zeolites,
silver copper zeolites, silver zeolites, metal oxides, and
silicates), crosslinkers or controlled degradation agents (e.g.,
peroxides, azo compounds, and silanes), colorants, pigments, dyes,
fluorescent whitening agents or optical brighteners (e.g.,
bis-benzoxazoles, phenylcoumarins, and bis-(styryl)biphenyls),
fillers (e.g., natural minerals and metals such as oxides,
hydroxides, carbonates, sulfates, and silicates; talc; clay;
wollastonite; graphite; carbon black; carbon fibers; glass fibers
and beads; ceramic fibers and beads; metal fibers and beads;
flours; and fibers of natural or synthetic origin such as fibers of
wood, starch, or cellulose flours), coupling agents (e.g., silanes,
titanates, zirconates, fatty acid salts, anhydrides, epoxies, and
unsaturated polymeric acids), reinforcement agents, crystallization
or nucleation agents (e.g., any material which increases or
improves the crystallinity in a polymer, such as to improve
rate/kinetics of crystal growth, number of crystals grown, or type
of crystals grown), and so forth.
[0023] According to some embodiments of the invention, a
temperature regulating material can include one or more phase
change materials. In general, a phase change material can include
any substance (or mixture of substances) that has the capability of
absorbing or releasing thermal energy to reduce or eliminate heat
flow at or within a temperature stabilizing range. The temperature
stabilizing range can include a particular transition temperature
or a range of transition temperatures. A phase change material used
in conjunction with various embodiments of the invention can be
capable of inhibiting a flow of thermal energy during a time when
the phase change material is absorbing or releasing heat, typically
as the phase change material undergoes a transition between two
states (e.g., liquid and solid states, liquid and gaseous states,
solid and gaseous states, or two solid states). This action is
typically transient, e.g., can last until a latent heat of the
phase change material is absorbed or released during a heating or
cooling process. As used herein, the term "latent heat" can refer
to an amount of heat absorbed or released by a substance (or
mixture of substances) as it undergoes a transition between two
states. Thermal energy can be stored or removed from a phase change
material, and the phase change material typically can be
effectively recharged by a source of heat or cold. By selecting an
appropriate phase change material, a polymeric composite can be
formed for any application thereof.
[0024] According to some embodiments of the invention, a phase
change material can be a solid/solid phase change material. A
solid/solid phase change material is a type of phase change
material that typically undergoes a transition between two solid
states (e.g., a crystalline or mesocrystalline phase
transformation) and, hence, typically does not become a liquid
during use.
[0025] A phase change material can include a mixture of two or more
substances. By selecting two or more different substances and
forming a mixture, a temperature stabilizing range can be adjusted
for any particular application of a polymeric composite. According
to some embodiments of the invention, a mixture of two or more
different substances can exhibit two or more distinct transition
temperatures or a single modified transition temperature when
incorporated in a polymeric composite.
[0026] Phase change materials that can be incorporated in polymeric
composites in accordance with various embodiments of the invention
include a variety of organic and inorganic substances. Examples of
phase change materials include hydrocarbons (e.g., straight chain
alkanes or paraffinic hydrocarbons, branched-chain alkanes,
unsaturated hydrocarbons, halogenated hydrocarbons, and alicyclic
hydrocarbons), hydrated salts (e.g., calcium chloride hexahydrate,
calcium bromide hexahydrate, magnesium nitrate hexahydrate, lithium
nitrate trihydrate, potassium fluoride tetrahydrate, ammonium alum,
magnesium chloride hexahydrate, sodium carbonate decahydrate,
disodium phosphate dodecahydrate, sodium sulfate decahydrate, and
sodium acetate trihydrate), waxes, oils, water, fatty acids, fatty
acid esters, dibasic acids, dibasic esters, 1-halides, primary
alcohols, aromatic compounds, clathrates, semi-clathrates, gas
clathrates, anhydrides (e.g., stearic anhydride), ethylene
carbonate, polyhydric alcohols (e.g., 2,2-dimethyl-1,3-propanediol,
2-hydroxymethyl-2-methyl-1,3-propanediol, ethylene glycol,
polyethylene glycol, pentaerythritol, dipentaerythrital,
pentaglycerine, tetramethylol ethane, neopentyl glycol,
tetramethylol propane, 2-amino-2-methyl-1,3-propanediol,
monoaminopentaerythritol, diaminopentaerythritol and
tris(hydroxymethyl)acetic acid), polymers (e.g., polyethylene,
polyethylene glycol, polyethylene oxide, polypropylene,
polypropylene glycol, polytetramethylene glycol, polypropylene
malonate, polyneopentyl glycol sebacate, polypentane glutarate,
polyvinyl myristate, polyvinyl stearate, polyvinyl laurate,
polyhexadecyl methacrylate, polyoctadecyl methacrylate, polyesters
produced by polycondensation of glycols (or their derivatives) with
diacids (or their derivatives), and copolymers, such as
polyacrylate or poly(meth)acrylate with alkyl hydrocarbon side
chain or with polyethylene glycol side chain and copolymers
including polyethylene, polyethylene glycol, polyethylene oxide,
polypropylene, polypropylene glycol, or polytetramethylene glycol),
metals, and mixtures thereof.
[0027] The selection of a phase change material will typically be
dependent upon a desired transition temperature or a desired
application of a resulting polymeric composite. For example, a
phase change material having a transition temperature near room
temperature can be desirable for applications in which the
resulting polymeric composite is incorporated into apparel or
footwear to maintain a comfortable temperature for a user.
[0028] A phase change material according to some embodiments of the
invention can have a transition temperature ranging from about
-40.degree. C. to about 125.degree. C., such as from about
-40.degree. C. to about 100.degree. C. or from about -5.degree. C.
to about 125.degree. C. In one embodiment useful for clothing
applications, the phase change material can have a transition
temperature ranging from about 0.degree. C. to about 50.degree. C.,
such as from about 10.degree. C. to about 50.degree. C., from about
15.degree. C. to about 45.degree. C., from about 22.degree. C. to
about 40.degree. C., or from about 22.degree. C. to about
28.degree. C. Also, the phase change material according to some
embodiments of the invention can have a latent heat that is at
least about 40 J/g, such as at least about 50 J/g, at least about
60 J/g, at least about 70 J/g, at least about 80 J/g, at least
about 90 J/g, or at least about 100 J/g. In one embodiment useful
for clothing applications, the phase change material can have a
latent heat ranging from about 40 J/g to about 400 J/g, such as
from about 60 J/g to about 400 J/g, from about 80 J/g to about 400
J/g, or from about 100 J/g to about 400 J/g.
[0029] According to some embodiments of the invention, particularly
useful phase change materials include paraffinic hydrocarbons
having from 10 to 44 carbon atoms (i.e., C.sub.10-C.sub.44
paraffinic hydrocarbons). Table 1 provides a list of C.sub.13-
C.sub.28 paraffinic hydrocarbons that can be used as phase change
materials in the polymeric composites described herein. The number
of carbon atoms of a paraffinic hydrocarbon typically correlates
with its melting point. For example, n-Octacosane, which includes
28 straight chain carbon atoms per molecule, has a melting point of
61.4.degree. C. By comparison, n-Tridecane, which includes 13
straight chain carbon atoms per molecule, has a melting point of
-5.5.degree. C. According to an embodiment of the invention,
n-Octadecane, which includes 18 straight chain carbon atoms per
molecule and has a melting point of 28.2.degree. C., is
particularly desirable for clothing applications.
1 TABLE 1 Paraffinic No. of Melting Hydrocarbon Carbon Atoms Point
(.degree. C.) n-Octacosane 28 61.4 n-Heptacosane 27 59.0
n-Hexacosane 26 56.4 n-Pentacosane 25 53.7 n-Tetracosane 24 50.9
n-Tricosane 23 47.6 n-Docosane 22 44.4 n-Heneicosane 21 40.5
n-Eicosane 20 36.8 n-Nonadecane 19 32.1 n-Octadecane 18 28.2
n-Heptadecane 17 22.0 n-Hexadecane 16 18.2 n-Pentadecane 15 10.0
n-Tetradecane 14 5.9 n-Tridecane 13 -5.5
[0030] Other useful phase change materials include polymeric phase
change materials having transition temperatures suitable for a
desired application of a polymeric composite (e.g., from about
22.degree. C. to about 40.degree. C. for clothing applications). A
polymeric phase change material can include a polymer (or a mixture
of polymers) having a variety of chain structures that include one
or more types of monomer units. In particular, polymeric phase
change materials can include linear polymers, branched polymers
(e.g., star branched polymers, comb branched polymers, or dendritic
branched polymers), or mixtures thereof. For certain applications,
a polymeric phase change material desirably includes a linear
polymer or a polymer with a small amount of branching to allow for
a greater density and a greater degree of ordered molecular packing
and crystallization. Such greater degree of ordered molecular
packing and crystallization can lead to a larger latent heat and a
narrower temperature stabilizing range (e.g., a well-defined
transition temperature). A polymeric phase change material can
include a homopolymer, a copolymer (e.g., terpolymer, statistical
copolymer, random copolymer, alternating copolymer, periodic
copolymer, block copolymer, radial copolymer, or graft copolymer),
or a mixture thereof. Properties of one or more types of monomer
units forming a polymeric phase change material can affect a
transition temperature of the polymeric phase change material.
Accordingly, the selection of the monomer units can be dependent
upon a desired transition temperature or a desired application of
polymeric composites that include the polymeric phase change
material. As one of ordinary skill in the art will understand, the
reactivity and functionality of a polymer can be altered by
addition of a functional group, such as amine, amide, carboxyl,
hydroxyl, ester, ether, epoxy, anhydride, isocyanate, silane,
ketone, and aldehyde. Also, a polymeric phase change material can
include a polymer capable of crosslinking, entanglement, or
hydrogen bonding in order to increase its toughness or its
resistance to heat, moisture, or chemicals.
[0031] As one of ordinary skill in the art will understand, some
polymers can be provided in various forms having different
molecular weights, since a molecular weight of a polymer can be
determined by processing conditions used for forming the polymer.
Accordingly, a polymeric phase change material can include a
polymer (or a mixture of polymers) having a particular molecular
weight or a particular range of molecular weights. As used herein,
the term "molecular weight" can refer to a number average molecular
weight, a weight average molecular weight, or a melt index of a
polymer (or a mixture of polymers).
[0032] According to some embodiments of the invention, a polymeric
phase change material can be desirable as a result of having a
higher molecular weight, a larger molecular size, or a higher
viscosity relative to non-polymeric phase change materials (e.g.,
paraffinic hydrocarbons). As a result of this larger molecular size
or higher viscosity, a polymeric phase change material can exhibit
a lesser tendency to leak from a polymeric composite during
processing or during end use. For some embodiments of the
invention, a polymeric phase change material can include polymers
having a number average molecular weight ranging from about 400 to
about 5,000,000, such as from about 2,000 to about 5,000,000, from
about 8,000 to about 100,000, or from about 8,000 to about 15,000.
When incorporated within a synthetic fiber, for example, its larger
molecular size or its higher viscosity can prevent a polymeric
phase change material from flowing through an exterior of the
fiber. In addition to providing thermal regulating properties, a
polymeric phase change material can provide improved mechanical
properties (e.g., ductility, tensile strength, and hardness) when
incorporated in articles in accordance with various embodiments of
the invention. If desired, a polymeric phase change material having
a desired transition temperature can be combined with a polymeric
material (e.g., a dispersing polymeric material or a matrix
polymeric material) to form a polymeric composite. According to
some embodiments of the invention, a polymeric phase change
material can provide adequate mechanical properties such that it
can be used to form a polymeric composite without requiring another
polymeric material, thus allowing for a higher loading level of the
polymeric phase change material and improved thermal regulating
properties. For example, it is contemplated that a polymeric phase
change material can be used as is or can serve as a dispersing
polymeric material to form a polymeric composite.
[0033] For example, polyethylene glycols can be used as a phase
change material in some embodiments of the invention. The number
average molecular weight of polyethylene glycol typically
correlates with its melting point. For example, polyethylene
glycols having a number average molecular weight in the range of
about 570 to about 630 (e.g., Carbowax.TM. 600, available from The
Dow Chemical Company, Midland, Mich.) typically will have a melting
point of about 20.degree. C. to about 25.degree. C., making them
desirable for clothing applications. Other polyethylene glycols
that can be useful at other temperature stabilizing ranges include
polyethylene glycols having a number average molecular weight of
about 400 and a melting point in the range of about 4.degree. C. to
about 8.degree. C., polyethylene glycols having a number average
molecular weight in the range of about 1,000 to about 1,500 and a
melting point in the range of about 42.degree. C. to about
48.degree. C., and polyethylene glycols having a number average
molecular weight of about 6,000 and a melting point in the range of
about 56.degree. C. to about 63.degree. C. (e.g., Carbowax.TM. 400,
1500, and 6000, available from The Dow Chemical Company, Midland,
Mich.).
[0034] Additional useful phase change materials include polymeric
phase change materials based on polyethylene glycols that are
endcapped with fatty acids. For example, polytetramethylene glycol
fatty acid diesters having a melting point in the range of about
22.degree. C. to about 35.degree. C. can be formed from
polyethylene glycols having a number average molecular weight in
the range of about 400 to about 600 that are endcapped with stearic
acid or lauric acid. Further useful phase change materials include
polymeric phase change materials based on tetramethylene glycol.
For example, polytetramethylene glycols having a number average
molecular weight in the range of about 1,000 to about 1,800 (e.g.,
Terathane.RTM. 1000 and 1800, available from DuPont Inc.,
Wilmington, Del.) typically have a melting point in the range of
about 19.degree. C. to about 36.degree. C. Polyethylene oxides
having a melting point in the range of about 60.degree. C. to about
65.degree. C. also can be used as phase change materials in some
embodiments of the invention.
[0035] For certain applications, polymeric phase change materials
can include homopolymers having a melting point in the range of
about 0.degree. C. to about 50.degree. C. that can be formed using
conventional polymerization processes. Table 2 sets forth melting
points of various homopolymers that can be formed from different
types of monomer units.
2TABLE 2 Melting Point Class of of Homopolymer Monomer Unit
Homopolymer (.degree. C.) Acrylates, Polyoctadecyl methacrylate 36
Methacrylates, Polyhexadecyl methacrylate 22 and and
Poly-N-tetradecyl polyacrylamide 18 Acrylamides Poly-N-tetradecyl
polyacrylamide- 32-35 1,1 dihydroperfluoro Alkanes and
Poly-1-decene 34-40 Alkenes Poly-1-heptene 17 cis-polyoctenamer 38
(Vestenamer .RTM. 6213, available from Degussa AG, Frankfurt,
Germany) Poly-1-octene 5-10 Poly-1-nonene 19-22 trans-polypentemer
23-34 Poly-1-undecene 36 cis-polyisoprene 28-36 syndiotactic
1,2-poly(1,3- 10 pentadiene) 1-methyl-polydodecamethylene 30 Ethers
Polymethyleneoxytetramethylene 30 oxide (Poly-1,3-dioxepane)
Polyhexamethyleneoxymethylene 38 oxide Polyoxacyclobutane (POX)
34-36 n-octadecyl polyacetaldehyde 18 Polytetramethylene glycol
1000 25-33 (Terathane .RTM. polyTHF 1000, available from DuPont
Inc., Wilmington, Delaware) Polytetramethylene glycol 1400 27-35
(Terathane .RTM. polyTHF 1400, available from DuPont Inc.,
Wilmington, Delaware) Polytetramethylene glycol 1800 27-38
(Terathane .RTM. polyTHF 1800, available from DuPont Inc.,
Wilmington, Delaware) Polytetramethylene glycol 2000 28-40
(Terathane .RTM. polyTHF 2000, available from DuPont Inc.,
Wilmington. Delaware) Vinyls Polydodecyl vinyl ether 30 Polyvinyl
laurate 16 Polyvinyl myristate 28 Sulfur
3,3-dimethyl-polytrimethylene 19 Containing sulfide Compounds
Polymethylene sulfide 35 Polytetramethylene disulfide 39-44
Polysulfur trioxide 32 1-methyl-trimethylene-poly- 35
sulfonyldivalerate Silicon beta-2-polydiethyl siloxane 17
Containing Nonamethylene-poly-disiloxanylene 10 Compounds
dipropionamide-diethyl, dimethyl (Si)
Nonamethylene-poly-disiloxanylene 10 dipropionamide-tetraethyl (Si)
Polymethyl hexadecyl siloxane 35 Amides and
Poly-(hexamethylene)cyclopropylene 20 Nitrogen
dicarboxamide-cis-N,N'-dibutyl Containing Poly-(hexamethylene)cycl-
opropylene 5 Compounds dicarboxamide-cis-N,N'-diethyl
Poly-(hexamethylene)cyclopropylene 20 dicarboxamide-cis-N,N'-diis-
opropyl Poly-(hexamethylene)cyclopropylene 30
dicarboxamide-cis-N,N'-dimethyl Polypentamethylene adipamide- 15
2,2,3,3,4,4 hexafluoro (diamine)- cis-N,N'-dibutyl
Polypentamethylene adipamide- 20 2,2,3,3,4,4 hexafluoro (diamine)-
cis-N,N'-diethyl Polypentamethylene adipamide- 35 2,2,3,3,4,4
hexafluoro (diamine)- cis-N,N'-diisopropyl Polypentamethylene
adipamide- 30 2,2,3,3,4,4 hexafluoro (diamine)- cis-N,N'-dimethyl
Poly-(4,4'-methylene diphenylene 32 sebacamide)-N,N'-diethyl
Polypentamethylene (hexamethylene 25 disulfonyl)-dicaproamide
Esters Poly-[ethylene 4,4'-oxydi- 19 methylene-di-2-(1,3-dioxo-
lane)- caprylate] Polypentamethylene adipate- 34 2,2,3,3,4,4 hexa
fluoro (4-methyl-(R+)-7- 36 polyhydroxyenanthic acid)
Poly-[4-hydroxy tetramethylene-2- 23 (1,3-dioxolane)caprylic acid]
(cis or trans) Polypentamethylene 2,2'-dibenzoate 13
Polytetramethylene 2,2'-dibenzoate 36 Poly-1-methyl-trimethylene 38
2,2' dibenzoate Polycaprolactone glycol 35-45 (Molecular weight =
830)
[0036] Further desirable phase change materials include polyesters
having a melting point in the range of about 0.degree. C. to about
40.degree. C. that can be formed, for example, by polycondensation
of glycols (or their derivatives) with diacids (or their
derivatives). Table 3 sets forth melting points of polyesters that
can be formed with various combinations of glycols and diacids.
3TABLE 3 Melting Point of Polyester Glycol Diacid (.degree. C.)
Ethylene glycol Carbonic 39 Ethylene glycol Pimelic 25 Ethylene
glycol Diglycolic 17-20 Ethylene glycol Thiodivaleric 25-28
1,2-Propylene glycol Diglycolic 17 Propylene glycol Malonic 33
Propylene glycol Glutaric 35-39 Propylene glycol Diglycolic 29-32
Propylene glycol Pimelic 37 1,3-butanediol Sulphenyl divaleric 32
1,3-butanediol Diphenic 36 1,3-butanediol Diphenyl methane-m,m'- 38
diacid 1,3-butanediol trans-H,H-terephthalic 18 acid Butanediol
Glutaric 36-38 Butanediol Pimelic 38-41 Butanediol Azelaic 37-39
Butanediol Thiodivaleric 37 Butanediol Phthalic 17 Butanediol
Diphenic 34 Neopentyl glycol Adipic 37 Neopentyl glycol Suberic 17
Neopentyl glycol Sebacic 26 Pentanediol Succinic 32 Pentanediol
Glutaric 22 Pentanediol Adipic 36 Pentanediol Pimelic 39
Pentanediol para-phenyl diacetic acid 33 Pentanediol Diglycolic 33
Hexanediol Glutaric 28-34 Hexanediol 4-Octenedioate 20 Heptanediol
Oxalic 31 Octanediol 4-Octenedioate 39 Nonanediol meta-phenylene
diglycolic 35 Decanediol Malonic 29-34 Decanediol Isophthalic 34-36
Decanediol meso-tartaric 33 Diethylene glycol Oxalic 10 Diethylene
glycol Suberic 28-35 Diethylene glycol Sebacic 36-44 Diethylene
glycol Phthalic 11 Diethylene glycol trans-H,H-terephthalic 25 acid
Triethylene glycol Sebacic 28 Triethylene glycol Sulphonyl
divaleric 24 Triethylene glycol Phthalic 10 Triethylene glycol
Diphenic 38 para-dihydroxy- Malonic 36 methyl benzene
meta-dihydroxy- Sebacic 27 methyl benzene meta-dihydroxy-
Diglycolic 35 methyl benzene
[0037] According to some embodiments of the invention, a polymeric
phase change material having a desired transition temperature can
be formed by reacting a phase change material (e.g., a phase change
material discussed above) with a polymer (or a mixture of
polymers). Thus, for example,-n-octadecylic acid (i.e., stearic
acid) can be reacted or esterified with polyvinyl alcohol to yield
polyvinyl stearate, or dodecanoic acid (i.e., lauric acid) can be
reacted or esterified with polyvinyl alcohol to yield polyvinyl
laurate. Various combinations of phase change materials (e.g.,
phase change materials with one or more functional. groups such as
amine, carboxyl, hydroxyl, epoxy, silane, sulfuric, and so forth)
and polymers can be reacted to yield polymeric phase change
materials having desired transition temperatures.
[0038] Polymeric phase change materials having desired transition
temperatures can be formed from various types of monomer units. For
example, similar to polyoctadecyl methacrylate, a polymeric phase
change material can be formed by polymerizing octadecyl
methacrylate, which can be formed by esterification of octadecyl
alcohol with methacrylic acid. Also, polymeric phase change
materials can be formed by polymerizing a polymer (or a mixture of
polymers). For example, poly-(polyethylene glycol) methacrylate,
poly-(polyethylene glycol) acrylate, poly-(polytetramethylene
glycol) methacrylate, and poly-(polytetramethylene glycol) acrylate
can be formed by polymerizing polyethylene glycol methacrylate,
polyethylene glycol acrylate, polytetramethylene glycol
methacrylate, and polytetramethylene glycol acrylate, respectively.
In this example, the monomer units can be formed by esterification
of polyethylene glycol (or polytetramethylene glycol) with
methacrylic acid (or acrylic acid). It is contemplated that
polyglycols can be esterified with allyl alcohol or
trans-esterified with vinyl acetate to form polyglycol vinyl
ethers, which in turn can be polymerized to form poly-(polyglycol)
vinyl ethers. In a similar manner, it is contemplated that
polymeric phase change materials can be formed from homologues of
polyglycols, such as ester or ether endcapped polyethylene glycols
and polytetramethylene glycols.
[0039] According to some embodiments of the invention, a
temperature regulating material can include a phase change material
in a raw form (e.g., the phase change material is non-encapsulated
at either a micro or macro level, i.e., not micro- or
macroencapsulated). During manufacture of a polymeric composite,
the phase change material in the raw form can be provided as a
solid in a variety of forms (e.g., bulk form, powders, pellets,
granules, flakes, and so forth) or as a liquid in a variety of
forms (e.g., molten form, dissolved in a solvent, and so
forth).
[0040] According to other embodiments of the invention, a
temperature regulating material can include a containment structure
that encapsulates, contains, surrounds, absorbs, or reacts with a
phase change material. The containment structure can facilitate
handling of the phase change material while offering a degree of
protection to the phase change material from manufacturing
conditions (e.g., high temperature or shear forces) associated with
forming a polymeric composite or articles made from the polymeric
composite. Moreover, the containment structure can serve to reduce
or prevent leakage of the phase change material from the polymeric
composite or from an article formed therefrom.
[0041] As an example of a containment structure, a temperature
regulating material can include microcapsules that contain a phase
change material, which microcapsules can be uniformly, or
non-uniformly, dispersed within a polymeric composite. The
microcapsules can be formed as hollow shells enclosing the phase
change material and can include individual microcapsules formed in
a variety of regular or irregular shapes (e.g., spherical,
ellipsoidal, and so forth) and sizes. The individual microcapsules
can have the same or different shapes or sizes. According to some
embodiments of the invention, the microcapsules can have a maximum
linear dimension (e.g., diameter) ranging from about 0.01 to about
100 microns. In one embodiment, the microcapsules can have a
generally spherical shape and a maximum linear dimension (e.g.,
diameter) ranging from about 0.5 to about 10 microns, such as from
about 0.5 to about 3 microns. Other examples of a containment
structure include silica particles (e.g., precipitated silica
particles, fumed silica particles, and mixtures thereof), zeolite
particles, carbon particles (e.g., graphite particles, activated
carbon particles, and mixtures thereof), and absorbent materials
(e.g., absorbent polymeric materials, superabsorbent materials,
cellulosic materials, poly(meth)acrylate materials, metal salts of
poly(meth)acrylate materials, and mixtures thereof). For example, a
temperature regulating material can include silica particles,
zeolite particles, carbon particles, or an absorbent material
impregnated with a phase change material.
[0042] According to some embodiments of the invention, a polymeric
composite can include up to about 100 percent by weight of a
temperature regulating material. In some embodiments, a polymeric
composite can include from about 5 percent to about 70 percent by
weight of a temperature regulating material. Thus, according to
some embodiments of the invention, a polymeric composite can
include from about 10 percent to about 30 percent or from about 15
percent to about 25 percent by weight of a temperature regulating
material. And, according to other embodiments, a polymeric
composite can include about 15 percent by weight of a temperature
regulating material. As further discussed below, some embodiments
of the invention employ water-wetted microcapsules containing a
phase change material to form a polymeric composite. In such
embodiments, a polymeric composite can include an amount of water
that is typically less than about 1 percent by weight.
[0043] According to some embodiments of the invention, a polymeric
composite can include two or more temperature regulating materials
that differ from one another in some fashion. For example, the two
temperature regulating materials can include two different phase
change materials or a phase change material in a raw form and a
phase change material in an encapsulated form. It is contemplated
that the phase change material in the raw form can include a
polymeric phase change material, which can serve as a dispersing
polymeric material to form the polymeric composite.
[0044] In general, a dispersing polymeric material can include any
polymer (or mixture of polymers) that facilitates incorporating a
temperature regulating material in a polymeric composite. In
embodiments where a polymeric phase change material serves as the
dispersing polymeric material, the polymeric phase change material
can be selected to have the characteristics discussed herein for
the dispersing polymeric material. According to some embodiments of
the invention, the dispersing polymeric material can be compatible
or miscible with or have an affinity for the temperature regulating
material. In some embodiments of the invention, such affinity can
depend on, for example, similarity of solubility parameters,
polarities, hydrophobic characteristics, or hydrophilic
characteristics of the dispersing polymeric material and the
temperature regulating material. Advantageously, such affinity can
facilitate dispersion of the temperature regulating material in an
intermediate molten or liquid form of the polymeric composite
during its manufacture (e.g., in a melt of the dispersing polymeric
material) and, thus, ultimately can facilitate incorporation of
more uniform or greater amounts or loading level of a phase change
material in the polymeric composite. In embodiments where the
temperature regulating material includes a containment structure
that contains a phase change material, the dispersing polymeric
material can be selected for its affinity for the containment
structure in conjunction with, or as an alternative to, its
affinity for the phase change material. In particular, if the
temperature regulating material includes microcapsules containing
the phase change material, the dispersing polymeric material can be
selected to have an affinity for the microcapsules (e.g., for a
material or materials of which the microcapsules are formed). Such
affinity can facilitate dispersion of the microcapsules containing
the phase change material in an intermediate molten or liquid form
of the polymeric composite (e.g., in a melt of the dispersing
polymeric material) and, thus, ultimately can facilitate
incorporation of more uniform or greater amounts or loading level
of the phase change material in the polymeric composite. For
example, the dispersing polymeric material can be selected to
include a polymer that is the same as or similar to a polymer
forming the microcapsules (e.g., if the microcapsules include nylon
shells, the dispersing polymeric material can be selected to
include nylon). As another example, the dispersing polymeric
material can be selected to include a polymer with one or more
functional groups, such as amine or epoxy, to provide such affinity
for the microcapsules (e.g., if the microcapsules include one or
more carboxyl groups, the dispersing polymeric material can be
selected to include a polymer with one or more epoxy groups, such
as polystearyl methacrylate-co-glycidyl methacrylate). Desirably,
the dispersing polymeric material can be selected to be
sufficiently non-reactive with the temperature regulating material
so that a desired temperature stabilizing range is maintained when
the temperature regulating material is dispersed within the
dispersing polymeric material.
[0045] For example, a dispersing polymeric material can include
high-density polyethylenes having a melt index in the range of
about 4 to about 36 g/10 min (e.g., high-density polyethylenes
having melt indices of 4, 12, and 36 g/10 min, available from
Sigma-Aldrich Corp., St. Louis, Mo.), modified forms of
high-density polyethylenes (e.g., Fusabond.RTM. E MB100D, available
from DuPont Inc., Wilmington, Del.), and modified forms of ethylene
propylene rubber (e.g., Fusabond .RTM. N MF416D, available from
DuPont Inc., Wilmington, Del.). As one of ordinary skill in the art
will understand, a melt index typically refers to a measure of the
flow characteristics of a polymer (or a mixture of polymers) and
typically inversely correlates with a molecular weight of the
polymer (or the mixture of polymers). For polar phase change
materials (e.g., polyethylene glycols, polytetramethylene glycols,
and their homologues), the dispersing polymeric material can
include a polar polymer (or a mixture of polar polymers) to
facilitate dispersion of the polar phase change materials. Thus,
for example, the dispersing polymeric material can include
copolymers of polyesters, such as polybutylene
terephthalate-block-polytetramethylene glycols (e.g., Hytrel.RTM.
3078, 5544, and 8238, available from DuPont Inc., Wilmington,
Del.), and copolymers of polyamides, such as
polyamide-block-polyethers (e.g., Pebax.RTM. 2533, 4033, 5533,
7033, MX 1205, and MH 1657, available from ATOFINA Chemicals, Inc.,
Philadelphia, Pa.).
[0046] According to some embodiments of the invention, a dispersing
polymeric material can have a slight or partial compatibility or
miscibility with or affinity for a temperature regulating material
(e.g., a semi-miscible polymer). Such partial affinity can be
adequate to facilitate dispersion of the temperature regulating
material and to facilitate processing at higher temperatures. At
lower temperatures and shear conditions and once a polymeric
composite has been formed, this partial affinity can allow the
temperature regulating material to separate out. For embodiments of
the invention where a phase change material in a raw form is used,
this partial affinity can lead to insolubilization of the phase
change material and increased phase change material domain
formation within the polymeric composite. According to some
embodiments of the invention, domain formation can lead to an
improved thermal regulating property by facilitating transition of
the phase change material between two states. In addition, domain
formation can serve to reduce or prevent loss or leakage of the
phase change material from the polymeric composite during
processing or during use.
[0047] For example, certain phase change materials such as
paraffinic hydrocarbons can be compatible with polyolefins or
copolymers of polyolefins at lower concentrations of the phase
change materials or when the temperature is above a critical
solution temperature. Thus, for example, mixing of a paraffinic
hydrocarbon (or a mixture of paraffinic hydrocarbons) and
polyethylene or polyethylene-co-vinyl acetate can be achieved at
higher temperatures and higher concentrations of the paraffinic
hydrocarbon to produce a homogenous blend that can be easily
controlled, pumped, and processed to form a polymeric composite.
Once the polymeric composite has been formed and has cooled, the
paraffinic hydrocarbon can become insoluble and can separate out
into distinct domains. These domains can allow for pure melting or
crystallization of the paraffinic hydrocarbon for an improved
thermal regulating property. In addition, these domains can serve
to reduce or prevent loss or leakage of the paraffinic hydrocarbon.
According to some embodiments of the invention, the
polyethylene-co-vinyl acetate can have between about 5 and about 90
percent by weight of the vinyl acetate, and, according to other
embodiments of the invention, the vinyl acetate content is between
about 5 and about 50 percent by weight. In one embodiment, the
vinyl acetate content is desirably between about 18 to about 25
percent by weight. This content of vinyl acetate can allow for
temperature miscibility control when mixing the paraffinic
hydrocarbon and the polyethylene-co-vinyl acetate to form a blend.
In particular, this vinyl acetate content can allow for excellent
miscibility at higher temperatures, thus facilitating melt spinning
process stability and control due to homogeneity of the blend. At
lower temperatures (e.g., room temperature or normal commercial
fabric use temperatures), the polyethylene-co-vinyl acetate is
semi-miscible with the paraffinic hydrocarbon, thus allowing for
separation and domain formation of the paraffinic hydrocarbon.
[0048] It should be recognized that a dispersing polymeric material
can be selected to be compatible or miscible with or have an
affinity for a matrix polymeric material. Here, the dispersing
polymeric material can serve as a compatibilizing link between a
temperature regulating material and the matrix polymeric material
to thereby facilitate incorporating the temperature regulating
material in a polymeric composite.
[0049] Typically, a dispersing polymeric material will include a
thermoplastic polymer (or a mixture of thermoplastic polymers)
(i.e., one that can be heated to form a melt and subsequently
shaped or molded to form a polymeric composite). According to some
embodiments of the invention, the dispersing polymeric material
desirably includes one or more low molecular weight polymers. A low
molecular weight polymer typically has a low viscosity when heated
to form a melt, which low viscosity can facilitate dispersion of a
temperature regulating material in the melt. As discussed
previously, some polymers can be provided in a variety of forms
having different molecular weights. Accordingly, as used herein,
the term "low molecular weight polymer" can refer to a low
molecular weight form of a polymer (e.g., a low molecular weight
form of a polymer discussed herein). For example, a polyethylene
having a number average molecular weight of about 20,000 (or less)
can be used as a low molecular weight polymer in an embodiment of
the invention. It should be recognized that a molecular weight or a
range of molecular weights associated with a low molecular weight
polymer can depend on the particular polymer selected (e.g.,
polyethylene) or on the method or equipment used to mix a
temperature regulating material with the low molecular weight
polymer.
[0050] A dispersing polymeric material can include a polymer (or a
mixture of polymers) having a variety of chain structures that
include one or more types of monomer units. In particular, the
dispersing polymeric material can include a linear polymer, a
branched polymer (e.g., star branched polymer, comb branched
polymer, or dendritic branched polymer), or a mixture thereof. The
dispersing polymeric material can include a homopolymer, a
copolymer (e.g., terpolymer, statistical copolymer, random
copolymer, alternating copolymer, periodic copolymer, block
copolymer, radial copolymer, or graft copolymer), or a mixture
thereof. As discussed previously, the reactivity and functionality
of a polymer can be altered by addition of a functional group, such
as amine, amide, carboxyl, hydroxyl, ester, ether, epoxy,
anhydride, isocyanate, silane, ketone, and aldehyde. The dispersing
polymeric material can include a polymer capable of crosslinking,
entanglement, or hydrogen bonding in order to increase its
toughness or its resistance to heat, moisture, or chemicals.
[0051] Examples of dispersing polymeric materials include
polyamides (e.g., Nylon 6, Nylon 6/6, Nylon 12, polyaspartic acid,
polyglutamic acid, and so forth), polyamines, polyimides,
polyacrylics (e.g., polyacrylamide, polyacrylonitrile, esters of
methacrylic acid and acrylic acid, and so forth), polycarbonates
(e.g., polybisphenol A carbonate, polypropylene carbonate, and so
forth), polydienes (e.g., polybutadiene, polyisoprene,
polynorbornene, and so forth), polyepoxides, polyesters (e.g.,
polyethylene terephthalate, polybutylene terephthalate,
polytrimethylene terephthalate, polycaprolactone, polyglycolide,
polylactide, polyhydroxybutyrate, polyhydroxyvalerate, polyethylene
adipate, polybutylene adipate, polypropylene succinate, and so
forth), polyethers (e.g., polyethylene glycol (polyethylene oxide),
polybutylene glycol, polypropylene oxide, polyoxymethylene
(paraformaldehyde), polytetramethylene ether (polytetrahydrofuran),
polyepichlorohydrin, and so forth), polyflourocarbons, formaldehyde
polymers (e.g., urea-formaldehyde, melamine-formaldehyde, phenol
formaldehyde, and so forth), natural polymers (e.g., cellulosics,
chitosans, lignins, waxes, and so forth), polyolefins (e.g.,
polyethylene, polypropylene, polybutylene, polybutene, polyoctene,
and so forth), polyphenylenes (e.g., polyphenylene oxide,
polyphenylene sulfide, polyphenylene ether sulfone, and so forth),
silicon containing polymers (e.g., polydimethyl siloxane,
polycarbomethyl silane, and so forth), polyurethanes, polyvinyls
(e.g., polyvinyl butyral, polyvinyl alcohol, polyvinyl acetate,
polystyrene, polymethylstyrene, polyvinyl chloride, polyvinyl
pryrrolidone, polymethyl vinyl ether, polyethyl vinyl ether,
polyvinyl methyl ketone, and so forth), polyacetals, polyarylates,
copolymers (e.g., polyethylene-co-vinyl acetate,
polyethylene-co-acrylic acid, polybutylene
terphthalate-co-polytetramethylene terephthalate,
polylauryllactam-block-polytetrahydrofuran, and so forth), and
mixtures thereof.
[0052] According to some embodiments of the invention, a polymeric
composite can include up to about 100 percent by weight of a
dispersing polymeric material. In some embodiments, a polymeric
composite can include from about 10 percent to about 30 percent by
weight of a dispersing polymeric material. And, according to one
embodiment, a polymeric composite can include about 15 percent by
weight of a dispersing polymeric material.
[0053] In general, a matrix polymeric material can include any
polymer (or mixture of polymers) that has or provides one or more
desired physical properties for a polymeric composite or an article
(e.g., a synthetic fiber) made therefrom. Examples of physical
properties include mechanical properties (e.g., ductility, tensile
strength, and hardness), thermal properties (e.g.,
thermoformability), and chemical properties (e.g., reactivity).
According to some embodiments of the invention, the matrix
polymeric material can be compatible or miscible with or have an
affinity for a dispersing polymeric material. In some embodiments
of the invention, such affinity can depend on, for example,
similarity of solubility parameters, polarities, hydrophobic
characteristics, or hydrophilic characteristics of the dispersing
polymeric material and the matrix polymeric material.
Advantageously, such affinity can facilitate forming a blend of the
matrix polymeric material, the dispersing polymeric material, and a
temperature regulating material during manufacture of the polymeric
composite and, thus, ultimately can facilitate incorporation of
more uniform or greater amounts or loading level of a phase change
material in the polymeric composite. As discussed previously, the
dispersing polymeric material can serve as a compatibilizing link
between the matrix polymeric material and the temperature
regulating material to thereby facilitate incorporating the
temperature regulating material in the polymeric composite.
[0054] It should be recognized that a matrix polymeric material can
be selected to be compatible or miscible with or have an affinity
for a temperature regulating material. In embodiments where the
temperature regulating material includes a containment structure
that contains a phase change material, the matrix polymeric
material can be selected for its affinity for the containment
structure in conjunction with, or as an alternative to, its
affinity for the phase change material. According to some
embodiments of the invention, the matrix polymeric material can
have a slight or partial compatibility or miscibility with or
affinity for the temperature regulating material. Such partial
affinity can be adequate to facilitate dispersion of the
temperature regulating material and to facilitate processing at
higher temperatures. At lower temperatures and shear conditions and
once a polymeric composite has been formed, this partial affinity
can allow the temperature regulating material to separate out. For
embodiments of the invention wherein a phase change material in a
raw form is used, this partial affinity can lead to
insolubilization of the phase change material and increased phase
change material domain formation within the polymeric
composite.
[0055] Typically, a matrix polymeric material will include a
thermoplastic polymer (or a mixture of thermoplastic polymers).
According to some embodiments of the invention, the matrix
polymeric material desirably includes one or more high molecular
weight polymers. A high molecular weight polymer typically has
enhanced physical properties (e.g., mechanical properties) but may
have a high viscosity when heated to form a melt. As discussed
previously, some polymers can be provided in a variety of forms
having different molecular weights. Accordingly, as used herein,
the term "high molecular weight polymer" can refer to a high
molecular weight form of a polymer (e.g., a high molecular weight
form of a polymer discussed herein). For example, a polyester
having a number average molecular weight of about 20,000 (or more)
can be used as a high molecular weight polymer in an embodiment of
the invention. It should be recognized that a molecular weight or a
range of molecular weights associated with a high molecular weight
polymer can depend on the particular polymer selected (e.g.,
polyester) or on the method or equipment used to mix a temperature
regulating material with the high molecular weight polymer.
[0056] As with a dispersing polymeric material, a matrix polymeric
material can include a polymer (or a mixture of polymers) having a
variety of chain structures that include one or more types of
monomer units. In particular, the matrix polymeric material can
include a linear polymer, a branched polymer (e.g., star branched
polymer, comb branched polymer, or dendritic branched polymer), or
a mixture thereof. The matrix polymeric material can include a
homopolymer, a copolymer (e.g., terpolymer, statistical copolymer,
random copolymer, alternating copolymer, periodic copolymer, block
copolymer, radial copolymer, or graft copolymer), or a mixture
thereof. As discussed previously, the reactivity and functionality
of a polymer can be altered by addition of a functional group, such
as an amine, amide, carboxyl, hydroxyl, ester, ether, epoxy,
anhydride, isocyanate, silane, ketone, and aldehyde, and the matrix
polymeric material can include a polymer capable of crosslinking,
entanglement, or hydrogen bonding in order to increase its
toughness or its resistance to heat, moisture, or chemicals.
[0057] Examples of matrix polymeric materials include polyamides
(e.g., Nylon 6, Nylon 6/6, Nylon 12, polyaspartic acid,
polyglutamic acid, and so forth), polyamines, polyimides,
polyacrylics (e.g., polyacrylamide, polyacrylonitrile, esters of
methacrylic acid and acrylic acid, and so forth), polycarbonates
(e.g., polybisphenol A carbonate, polypropylene carbonate, and so
forth), polydienes (e.g., polybutadiene, polyisoprene,
polynorbornene, and so forth), polyepoxides, polyesters (e.g.,
polyethylene terephthalate, polybutylene terephthalate,
polytrimethylene terephthalate, polycaprolactone, polyglycolide,
polylactide, polyhydroxybutyrate, polyhydroxyvalerate, polyethylene
adipate, polybutylene adipate, polypropylene succinate, and so
forth), polyethers (e.g., polyethylene glycol (polyethylene oxide),
polybutylene glycol, polypropylene oxide, polyoxymethylene
(paraformaldehyde), polytetramethylene ether (polytetrahydrofuran),
polyepichlorohydrin, and so forth), polyflourocarbons, formaldehyde
polymers (e.g., urea-formaldehyde, melamine-formaldehyde, phenol
formaldehyde, and so forth), natural polymers (e.g., cellulosics,
chitosans, lignins, waxes, and so forth), polyolefins (e.g.,
polyethylene, polypropylene, polybutylene, polybutene, polyoctene,
and so forth), polyphenylenes (e.g., polyphenylene oxide,
polyphenylene sulfide, polyphenylene ether sulfone, and so forth),
silicon containing polymers (e.g., polydimethyl siloxane,
polycarbomethyl silane, and so forth), polyurethanes, polyvinyls
(e.g., polyvinyl butryal, polyvinyl alcohol, polyvinyl acetate,
polystyrene, polymethylstyrene, polyvinyl chloride, polyvinyl
pryrrolidone, polymethyl vinyl ether, polyethyl vinyl ether,
polyvinyl methyl ketone, and so forth), polyacetals, polyarylates,
copolymers (e.g., polyethylene-co-vinyl acetate,
polyethylene-co-acrylic acid, polybutylene
terphthalate-co-polytetramethylene terephthalate,
polylauryllactam-block-polytetrahydrofuran, and so forth), and
mixtures thereof.
[0058] According to some embodiments of the invention, a polymeric
composite can include up to about 100 percent by weight of a matrix
polymeric material. In some embodiments, a polymeric composite can
include from about 40 percent to about 80 percent by weight of a
matrix polymeric material. And, according to one embodiment, a
polymeric composite can include about 70 percent by weight of a
matrix polymeric material.
[0059] At this point, those of ordinary skill in the art can
appreciate a number of advantages associated with various
embodiments of the invention. For example, a polymeric composite in
accordance with some embodiments of the invention can provide
improved thermal regulating properties, which allow for an improved
level of comfort when the polymeric composite is incorporated in
articles such as apparel or footwear. A polymeric composite in
accordance with some embodiments of the invention can include a
high loading level of one or more phase change materials within the
polymeric composite. According to some embodiments of the
invention, such high loading level can be provided because a
dispersing polymeric material can facilitate incorporating a
temperature regulating material in the polymeric composite.
Advantageously, a polymeric composite can also include a matrix
polymeric material selected to improve the polymeric composite's
overall physical properties (e.g., mechanical properties) and
processability (e.g., by facilitating its formation as described
herein). According to some embodiments of the invention, a
polymeric phase change material can provide adequate mechanical
properties and can be used as a dispersing polymeric material, thus
allowing for an even higher loading level and further improved
thermal regulating properties.
[0060] According to some embodiments of the invention, a polymeric
composite can have a latent heat that is at least about 2 J/g, such
as at least about 10 J/g, at least about 20 J/g, at least about 30
J/g, at least about 40 J/g, at least about 50 J/g, or at least
about 60 J/g. In one embodiment, the polymeric composite can have a
latent heat ranging from about 2 J/g to about 200 J/g, such as from
about 20 J/g to about 200 J/g, from about 40 J/g to about 200 J/g,
or from about 60 J/g to about 200 J/g.
[0061] A general approach to forming a polymeric composite
according to some embodiments of the invention is discussed below.
Initially, a temperature regulating material, a dispersing
polymeric material, and a matrix polymeric material are provided.
As discussed previously, the temperature regulating material can
include a phase change material and can further include a
containment structure (e.g., microcapsules) to encapsulate,
contain, surround, or absorb the phase change material. According
to some embodiments of the invention, the dispersing polymeric
material can include a low molecular weight polymer having an
affinity for the containment structure or the phase change
material, and the matrix polymeric material can include a high
molecular weight polymer having an affinity for the dispersing
polymeric material and providing one or more desired physical
properties to the polymeric composite or to an article made
therefrom. As discussed previously, it is also contemplated that a
polymeric phase change material can be used as the dispersing
polymeric material, and the matrix polymeric material can be
omitted for some embodiments of the invention.
[0062] Next, the temperature regulating material is mixed with the
dispersing polymeric material to form a first blend. According to
some embodiments of the invention, the dispersing polymeric
material is melted to form a first melt, and the temperature
regulating material is dispersed in the first melt to form the
first blend.
[0063] A second blend is then formed using the first blend and the
matrix polymeric material. According to some embodiments of the
invention, the first blend is processed to form granules, and the
granules are mixed with the matrix polymeric material to form the
second blend. In particular, the matrix polymeric material can be
melted to form a second melt, and the granules can be dispersed in
the second melt to form the second blend. Alternatively, the second
blend can be formed by melting the granules and adding the matrix
polymeric material thereto. According to other embodiments of the
invention, the granules need not be formed, and the first blend is
mixed with the matrix polymeric material to form the second
blend.
[0064] Once formed, the second blend is processed to form the
polymeric composite. According to some embodiments of the
invention, the second blend is processed to form pellets having
enhanced reversible thermal properties provided by the phase change
material incorporated therein.
[0065] The invention is more fully appreciated with reference to
FIG. 1, which illustrates a manufacturing process for forming a
polymeric composite in accordance with an embodiment of the
invention.
[0066] With reference to FIG. 1, a temperature regulating material
is provided (step 10). In the present embodiment, the temperature
regulating material includes a phase change material and
microcapsules that contain the phase change material. Here, the
temperature regulating material can further include an amount of
water wetting, coating, or absorbed by the microcapsules to form
water-wetted microcapsules. These water-wetted microcapsules can
form a wet cake. The wet cake can include from about 1 percent to
about 90 percent by weight of the microcapsules and the phase
change material with a remaining portion including water.
Typically, the wet cake includes from about 60 percent to about 70
percent by weight of the microcapsules and the phase change
material with a remaining portion including water. According to
some embodiments of the invention, use of this wet cake can serve
to facilitate handling of the microcapsules or can improve
dispersion (e.g., prevent lumping) of the microcapsules in a
melt.
[0067] As an alternative to or in conjunction with the
microcapsules, other containment structures can be used to
encapsulate, contain, surround, or absorb the phase change
material. Also, it should be recognized that the temperature
regulating material can alternatively, or in conjunction, include a
phase change material in a raw form. The phase change material in
the raw form can be provided as a solid in a variety of forms
(e.g., bulk form, powders, pellets, granules, flakes, and so forth)
or as a liquid in a variety of forms (e.g., molten form, dissolved
in a solvent, and so forth).
[0068] Next, a dispersing polymeric material is provided (step 11).
As discussed previously, the dispersing polymeric material can
include any polymer (or mixture of polymers) that facilitates
incorporating the temperature regulating material in the polymeric
composite. In the present embodiment, the dispersing polymeric
material includes a low molecular weight polymer having an affinity
for the microcapsules. It should be recognized that the dispersing
polymeric material can include one or more additional polymers
(e.g., one or more additional low molecular weight polymers). It is
also contemplated that the dispersing polymeric material can
include a polymeric phase change material.
[0069] As shown in FIG. 1, the temperature regulating material is
mixed with the dispersing polymeric material to form a first blend
(step 12). In accordance with the present embodiment, the
dispersing polymeric material is initially melted to form a first
melt (e.g., in a heated mixing bowl or in a wet flushing
apparatus), and the temperature regulating material (e.g., the wet
cake) is added to and dispersed in the first melt to form the first
blend. Uniform dispersion of the microcapsules containing the phase
change material in the first melt can be facilitated by the
affinity of the dispersing polymeric material for the
microcapsules. Also, dispersion can be facilitated by maintaining
the dispersing polymeric material in a molten state or by mixing
(e.g., agitation or stirring). In the present embodiment, the water
of the wet cake can be substantially removed by wet flushing. In
particular, the first blend can be heated until the water of the
wet cake is substantially eliminated such that, for example, the
first blend includes less than about 1 percent by weight of water.
It should be recognized that step 12 can alternatively include dry
blending the temperature regulating material with the dispersing
polymeric material to form a dry blend, which can be subsequently
heated to form the first blend.
[0070] Once formed, the first blend is processed to form granules
(steps 14 and 15). In the present embodiment, the first blend is
cooled to form a first solid (step 14), and the first solid is
granulated to form the granules (step 15). According to some
embodiments of the invention, the first blend is extruded, for
example, into a thread (or threads), which thread is cooled and
subsequently granulated to form the granules. Extrusion can be
performed using any extruder (including any conventional extruder
such as a single screw extruder) to form a thread having a variety
of regular or irregular cross sectional shapes.
[0071] In general, any method (including any conventional method)
can be used to granulate the first solid. For example, the first
solid can be pulverized, cut, or chopped using any conventional
method to form the granules. The granules can be formed with a
variety of shapes (e.g., spherical, ellipsoidal, cylindrical,
powdered form, irregularly shaped, and so forth) and sizes. The
granules can have the same or different shapes or sizes and can be
formed with smooth or rough surfaces. According to some embodiments
of the invention, the granules can have a maximum linear dimension
(e.g., length or diameter) ranging from about 0.01 to about 10
millimeters and typically from about 1 to about 5 millimeters.
[0072] The granules can include from about 30 percent to about 60
percent by weight of the temperature regulating material (e.g., by
dry weight of the microcapsules and the phase change material
dispersed therein) with a remaining portion including the
dispersing polymeric material. According to some embodiments of the
invention, the granules typically include from about 45 percent to
about 55 percent by weight of the microcapsules and the phase
change material with a remaining portion including the dispersing
polymeric material. As discussed above, the granules can also
include a small amount of water (e.g., less than about 1 percent by
weight of water).
[0073] A matrix polymeric material is then provided (step 18), and,
as discussed previously, the matrix polymeric material can include
any polymer (or mixture of polymers) that provides one or more
desired physical properties for the polymeric composite or for an
article made therefrom. In the present embodiment, the matrix
polymeric material includes a high molecular weight polymer having
an affinity for the dispersing polymeric material and providing
desired physical properties, such as desired mechanical or thermal
properties. It should be recognized that the matrix polymeric
material can include one or more additional polymers (e.g., one or
more additional high molecular weight polymers). It is also
contemplated that the matrix polymeric material can be omitted for
some embodiments of the invention.
[0074] The granules formed from step 15 are mixed with the matrix
polymeric material to form a second blend (step 17). In accordance
with the present embodiment, the matrix polymeric material is
initially melted to form a second melt, and the granules are added
to and dispersed in the second melt to form the second blend.
Dispersion of the granules in the second melt can be facilitated by
the affinity of the matrix polymeric material for the dispersing
polymeric material. Moreover, the granules typically melt after
being added to the second melt to release the microcapsules
containing the phase change material, and uniform dispersion of the
microcapsules in the second melt can be facilitated by the affinity
of the matrix polymeric material for the dispersing polymeric
material and the affinity of the dispersing polymeric material for
the microcapsules. Dispersion can also be facilitated by
maintaining the matrix polymeric material in a molten state or by
mixing (e.g., agitation or stirring). In the present embodiment,
the water of the wet cake can be further removed by wet flushing.
It should be recognized that step 17 can alternatively include dry
blending the granules with the matrix polymeric material to form a
dry blend, which can be subsequently heated to form the second
blend.
[0075] Once formed, the second blend is processed to form the
polymeric composite (steps 20 and 21). As discussed previously, the
polymeric composite can be formed in a variety of shapes, such as
pellets, fibers, flakes, sheets, films, rods, and so forth. In the
present embodiment, the second blend is cooled to form a second
solid (step 20), and the second solid is granulated to form pellets
(step 21). According to some embodiments of the invention, the
second blend is extruded, for example, into a thread (or threads),
which thread is cooled and subsequently granulated to form the
pellets. Extrusion can be performed using any extruder (including
any conventional extruder such as a single screw extruder) to form
a thread having a variety of regular or irregular cross sectional
shapes.
[0076] In general, any method (including any conventional method)
can be used to granulate the second solid. For example, the second
solid can be pulverized, cut, or chopped using any conventional
method to form the pellets. The pellets can be formed with a
variety of shapes (e.g., spherical, ellipsoidal, cylindrical,
powdered form, irregularly shaped, and so forth) and sizes. The
pellets can have the same or different shapes or sizes and can be
formed with smooth or rough surfaces. According to some embodiments
of the invention, the pellets can have a maximum linear dimension
(e.g., length or diameter) ranging from about 1 to about 10
millimeters and typically from about 1 to about 5 millimeters.
[0077] According to the present embodiment of the invention, the
formed pellets typically include from about 10 percent to about 30
percent by weight of the temperature regulating material (e.g., the
microcapsules and the phase change material), from about 10 percent
to about 30 percent by weight of the dispersing polymeric material,
and from about 40 percent to about 80 percent by weight of the
matrix polymeric material. In addition, the pellets can include an
amount of water that is typically less than about 1 percent by
weight. The pellets can be used to form a variety of articles
having enhanced reversible thermal properties, such as synthetic
fibers, films, and injection molded articles.
[0078] FIG. 2 illustrates a manufacturing process to form a
polymeric composite in accordance with another embodiment of the
invention. As with the previous embodiment, a temperature
regulating material, a dispersing polymeric material, and a matrix
polymeric material are provided (steps 30-32). As discussed
previously, it is also contemplated that a polymeric phase change
material can be used as the dispersing polymeric material, and the
matrix polymeric material can be omitted for some embodiments of
the invention.
[0079] As shown in FIG. 2, the temperature regulating material, the
dispersing polymeric material, and the matrix polymeric material
are then mixed together (step 33). In accordance with the present
embodiment, the dispersing polymeric material is initially melted
to form a first melt, and the temperature regulating material is
added to and dispersed in the first melt to form a first blend. If
present, water can be substantially removed by wet flushing. It
should be recognized that the temperature regulating material can
alternatively be dry blended with the dispersing polymeric material
to form a dry blend, which can be subsequently heated to form the
first blend. Next, the first blend is mixed with the matrix
polymeric material to form a second blend. The matrix polymeric
material can be initially melted to form a second melt, and the
first blend can be mixed with the second melt to form the second
blend. Alternatively, the matrix polymeric material can be added to
and dispersed in the first blend to form the second blend.
[0080] It should be recognized that the temperature regulating
material, the dispersing polymeric material, and the matrix
polymeric material can be mixed together using a variety of other
methods to form the second blend. For example, a polymeric blend of
the dispersing polymeric material and the matrix polymeric material
can be formed, and the temperature regulating material can be
subsequently added to and dispersed in the polymeric blend to form
the second blend. As another example, the temperature regulating
material, the dispersing polymeric material, and the matrix
polymeric material can be dry blended to form a dry blend, which
can be subsequently heated to form the second blend. As a further
example, the temperature regulating material, the dispersing
polymeric material, and the matrix polymeric material can be
provided together, heated, and mixed to form the second blend. In
particular, the temperature regulating material, the dispersing
polymeric material, and the matrix polymeric material can be fed
into an extruder to form the second blend, according to some
embodiments of the invention.
[0081] Once formed, the second blend is processed to form the
polymeric composite (steps 35 and 36). As discussed previously, the
polymeric composite can be formed in a variety of shapes, such as
pellets, fibers, flakes, sheets, films, rods, and so forth. In the
present embodiment, the second blend is cooled to form a solid
(step 35), and the solid is granulated to form pellets (step 36).
According to some embodiments of the invention, the second blend is
extruded, for example, into a thread (or threads), which thread is
cooled and subsequently granulated to form the pellets.
[0082] Turning next to FIG. 3, a manufacturing process to form a
polymeric composite in accordance with a further embodiment of the
invention is illustrated. In the present embodiment, the polymeric
composite is formed using a multistage extruder 43. A multistage
extruder is typically understood to include two or more extruder
units that can be operatively connected in a variety of
configurations (e.g., in series), wherein each extruder unit can be
a single or multiple screw extruder, can have one or more inlet
openings to receive a substance to be extruded, and can have one or
more discharge ports to vent gases such as air, water (e.g.,
steam), and volatile materials.
[0083] As shown in FIG. 3, a temperature regulating material and a
dispersing polymeric material are provided (steps 40 and 41) and
are fed into the multistage extruder 43. As discussed previously,
it is also contemplated that a polymeric phase change material can
be used as the dispersing polymeric material for some embodiments
of the invention. In the present embodiment, the temperature
regulating material and the dispersing polymeric material can be
fed into the same inlet opening or different inlet openings of the
multistage extruder 43. Within the multistage extruder 43, the
temperature regulating material is mixed with the dispersing
polymeric material to form a first blend, and the first blend is
advanced through the multistage extruder 43 along a melt stream
path 44.
[0084] Next, a matrix polymeric material is provided (step 42) and
is fed into the multistage extruder 43. As discussed previously, it
is also contemplated that the matrix polymeric material can be
omitted for some embodiments of the invention. In the present
embodiment, the matrix polymeric material is fed into an inlet
opening downstream along the melt stream path 44. Alternatively,
the matrix polymeric material can be fed into an inlet opening
upstream along the melt stream path 44 (e.g., the same inlet
opening used to receive the temperature regulating material or the
dispersing polymeric material). Within the multistage extruder 43,
the first blend is mixed with the matrix polymeric material to form
a second blend. As shown in FIG. 3, water, if present, can be
substantially removed through a discharge port (step 45).
[0085] Once formed, the second blend is processed to form the
polymeric composite (step 46). As discussed previously, the
polymeric composite can be formed in a variety of shapes, such as
pellets, fibers, flakes, sheets, films, rods, and so forth. For
example, the second blend can be extruded through a die into a
thread (or threads), which thread is cooled and subsequently
granulated to form pellets. As another example, the second blend
can be extruded through a spinneret to form synthetic fibers.
[0086] As discussed previously, polymeric composites in accordance
with some embodiments of the invention can be formed using one or
more phase change materials in a raw form. For example, the
manufacturing processes discussed above in connection with FIG. 1,
FIG. 2, and FIG. 3 can employ a temperature regulating material
that, alternatively or in conjunction, includes a phase change
material in a raw form. The phase change material in the raw form
can be provided as a solid in a variety of forms (e.g., bulk form,
powders, pellets, granules, flakes, and so forth) or as a liquid in
a variety of forms (e.g., molten form, dissolved in a solvent, and
so forth) (e.g., at step 10 of FIG. 1, at step 30 of FIG. 2, or at
step 40 of FIG. 3). For some embodiments of the invention, a phase
change material in a raw form is incorporated into a polymeric
composite, wherein the phase change material can be contained
within one or more isolated volumes or spaces that are dispersed
throughout the polymeric composite. As discussed previously, it is
also contemplated that a polymeric phase change material can be
used as a dispersing polymeric material, and the polymeric phase
change material can be used in a raw form.
[0087] According to some embodiments of the invention, a phase
change material in a raw form can be introduced at virtually any
time during a manufacturing process to form a polymeric composite
(e.g., at virtually any of the steps illustrated in FIG. 1, FIG. 2,
and FIG. 3). For example, a phase change material can be introduced
via liquid injection or by feeding the phase change material in a
solid form alone or in conjunction with a dispersing polymeric
material or a matrix polymeric material. A phase change material in
a raw liquid form can be filtered or mixed to insure homogeneity
prior to liquid injection. A phase change material in a raw solid
form can be fed into a feed throat of an extruder or can be side
stuffed into the extruder in order to prevent feed throat plugging.
According to some embodiments of the invention, a phase change
material in a raw form is desirably introduced at a later time
during a manufacturing process to thereby ensure adequate
dispersion of the phase change material or to reduce its exposure
to manufacturing conditions (e.g., high temperature or shear
forces) associated with forming a polymeric composite. By using
such a late-stage addition of the phase change material, exposure
of the phase change material to elevated temperatures and any
subsequent degradation or loss of the phase change material can be
reduced.
[0088] Various other embodiments are within the spirit and scope of
the invention. For example, as discussed previously, a polymeric
composite in accordance with some embodiments of the invention can
include a temperature regulating material and either a dispersing
polymeric material or a matrix polymeric material. Either the
dispersing polymeric material or the matrix polymeric material can
be selected to have an affinity for (or a slight or partial
affinity for) the temperature regulating material. According to an
embodiment of the invention, the polymeric composite can include
the temperature regulating material and the matrix polymeric
material that desirably includes one or more high molecular weight
polymers. In forming the polymeric composite, the temperature
regulating material and either the dispersing polymeric material or
the matrix polymeric material can be mixed to form a blend, and the
blend can then be processed to form the polymeric composite.
[0089] As discussed previously, polymeric composites in accordance
with some embodiments of the invention can be processed to form a
variety of articles having enhanced reversible thermal properties.
For example, pellets formed in accordance with some embodiments of
the invention can be used to form synthetic fibers, for injection
molding processes, or for extrusion processes. In particular, the
pellets can be used in a melt spinning process to form synthetic
fibers including, for example, from about 10 percent to about 30
percent by weight of a temperature regulating material. Once
formed, the synthetic fibers can be collected into a strand or cut
into staple fibers. The synthetic fibers can be used to make woven
or non-woven fabrics, or, alternatively, the synthetic fibers can
be wound into a yarn to be used thereafter in a weaving or a
knitting process to form a synthetic fabric. It should be
recognized that the pellets can be mixed with one or more polymers
(e.g., one or more thermoplastic polymers) to form a blend, which
one or more polymers can be the same as or different from
polymer(s) included in the pellets. The resulting blend can then be
processed to form synthetic fibers including, for example, from
about 5 percent to about 10 percent by weight of the temperature
regulating material. In addition, one or more thermoplastic
polymers can be used in conjunction with the pellets to form
multi-component melt spun fibers (e.g., bi-component fibers),
multi-component extruded films, multi-component injection molded
products, and so forth.
EXAMPLES
[0090] The following examples describe specific aspects of some
embodiments of the invention to illustrate and provide a
description for those of ordinary skill in the art. The examples
should not be construed as limiting the invention, as the examples
merely provide specific methodology useful in understanding and
practicing some embodiments of the invention.
Example 1
[0091] About 5.0 pounds of a low molecular weight polyethylene
homopolymer (AC-16 polyethylene, drop point of 102.degree. C.,
manufactured by Honeywell Specialty Chemical) was added to a wet
flushing apparatus, and the homopolymer was then slowly melted and
mixed at about 110.degree. C. to about 130.degree. C. Once the
homopolymer was melted, about 8.47 pounds of a wet cake was slowly
added to the molten homopolymer over about a 30 minute time period
to form a first blend. The wet cake included water-wetted
microcapsules containing a phase change material (micro PCM lot# M
42-31, 59.0 percent by weight of the microcapsules and the phase
change material, manufactured by MicroTek Laboratories, Inc.).
[0092] Water was flashed off as the microcapsules containing the
phase change material was added to and dispersed in the molten
homopolymer. Mixing continued until less than about 0.15 percent by
weight of the water remained (as measured using Karl-Fischer
titration). The resulting first blend was then cooled to form a
first solid, and the first solid was chopped to form a chopped
material for further processing. The chopped material included
about 50 percent by weight of the microcapsules and the phase
change material.
[0093] A dry blend was then formed by dry blending about 30 pounds
of the chopped material with about 70 pounds of a high molecular
weight fiber-grade polypropylene thermoplastic polymer
(Polypropylene homopolymer 6852 from PB Amoco Polymers).
[0094] The resulting dry blend was then extruded using a 21/2 inch
single screw extruder with all zones set at about 230.degree. C.,
with a screw speed of about 70 rpm, with 150 mesh screens, and with
a nitrogen purge, thus producing pellets. The pellets were then
oven dried overnight at about 50.degree. C. and at about 1 mm Hg of
vacuum.
[0095] The pellets, including about 15 percent by weight of the
microcapsules and the phase change material, were then
extruded/melt spun at temperatures between about 230.degree. C. and
265.degree. C. (e.g., between about 235.degree. C. to 245.degree.
C.).
[0096] Synthetic fibers were spun/wound at take-up speeds of up to
about 1600 meters per minute (mpm) to yield from about 20 to about
6 deniers per fiber, and the synthetic fibers exhibited enhanced
reversible thermal properties provided by the phase change material
as discussed in Example 2.
Example 2
[0097] Differential Scanning Calorimeter (DSC) measurements of the
above synthetic fibers were made using a Perkin Elmer Pyris 1
instrument. Cooling was accomplished using a FTS Systems
Intercoller 1. Data analysis was performed using a Perkin Elmer
Pyris Thermal Analysis System and Software for Windows, version
3.72.
[0098] Test samples were prepared in Perkin Elmer hermetically
sealed aluminum sample pans, and testing was performed while the
test samples were continuously subjected to N.sub.2 flow.
[0099] Test conditions included: 1) cooling the test samples to
about -10.degree. C.; 2) isothermal hold for about 1 minute at
-10.degree. C.; 3) heating from -10.degree. C. to about 50.degree.
C. at a rate of about 5.degree. C. per minute; 4) isothermal hold
for about 1 minute at 50.degree. C.; and then 5) cooling from
50.degree. C. to about -10.degree. C. at a rate of about 5.degree.
C. per minute.
[0100] Using the DSC measurements as described above, the synthetic
fibers provided between about 17.5 and 23.2 J/g of thermal energy
storage capacity (i.e., latent heat).
Example 3
[0101] About 3.1307 grams of a phase change material in a raw form
(Kenwax 19 paraffin, blend of C18 through C24 paraffinic
hydrocarbons, 150 J/g latent heat) was placed in a vial, and about
3.1255 grams of a polymeric material (Elvax 450, 18 percent by
weight of vinyl acetate, polyethylene-co-vinyl acetate polymer
supplied by DuPont Inc.) having a slight or partial affinity for
the phase change material was added to the vial. The phase change
material and the polymeric material were mixed together at between
120.degree. C. to 130.degree. C. by hand to produce a 50:50 by
weight blend that was homogeneous and clear. Upon cooling, a
polymeric composite was formed, which polymeric composite was hazy
and rubbery and without a waxy or greasy feel. A DSC measurement of
the polymeric composite showed 73.3 J/g of thermal energy storage
capacity, which corresponds to 48.9 percent of the Kenwax 19
available to provide a thermal regulating property.
[0102] A practitioner of ordinary skill in the art requires no
additional explanation in developing the polymeric composites
described herein but may nevertheless find some helpful guidance by
examining the patent of Hartmann, entitled "Stable Phase Change
Materials for Use in Temperature Regulating Synthetic Fibers,
Fabrics And Textiles," U.S. Pat. No. 6,689,466, issued on Feb. 10,
2004, and the patent of Magill et al., entitled "Multi-component
Fibers Having Enhanced Reversible Thermal Properties and Methods of
Manufacturing Thereof," U.S. Pat. No. 6,855,422, issued on Feb. 15,
2005, the disclosures of which are incorporated herein by reference
in their entirety.
[0103] Each of the patent applications, patents, publications, and
other published documents mentioned or referred to in this
specification is herein incorporated by reference in its entirety,
to the same extent as if each individual patent application,
patent, publication, and other published document was specifically
and individually indicated to be incorporated by reference.
[0104] While the invention has been described with reference to the
specific embodiments thereof, it should be understood by those
skilled in the art that various changes may be made and equivalents
may-be substituted without departing from the true spirit and scope
of the invention, as defined by the appended claims. In addition,
many modifications may be made to adapt a particular situation,
material, composition of matter, method, process step or steps, to
the objective, spirit and scope of the invention. All such
modifications are intended to be within the scope of the claims
appended hereto. In particular, while the methods disclosed herein
have been described with reference to particular steps performed in
a particular order, it will be understood that these steps may be
combined, sub-divided, or re-ordered to form an equivalent method
without departing from the teachings of the present invention.
Accordingly, unless specifically indicated herein, the order and
grouping of the steps is not a limitation of the invention.
* * * * *